Chiral α-aminoxy Acid / Achiral Cyclopropane α-aminoxy Acid Unit as a Building Block for Constructing α N O Helix

Chiral α-aminoxy Acid / Achiral Cyclopropane α-aminoxy Acid Unit as a Building Block for Constructing α elix Dan Yang,*,, Xiao-Wei Chang, Dan-Wei Zhang,*, Ze-Feng Jiang, Ke-Sheng Song, Yu-ui Zhang, ian-yong Zhu, Lin-ong Weng, Min-Qin Chen Department of Chemistry, Fudan University, Shanghai 200433, China, and Department of Chemistry, The University of ong Kong, Pokfulam Road, ong Kong, China Supporting Information I. General experimental methods... S2 II. Synthetic schemes and characterization data of compounds 1 22.... S3 III. 1 MR experimental result of compound 1.... S12 IV. Theoretical study results: energies and Cartesian coordinates for models I IV.... S13 VI. X-Ray data of compounds 1, 2, and 8.... S30 VII. MR spectra of compounds 1 22... S61 S1

I. General experimental methods 1 MR spectra were recorded at 300 or 400 Mz, 13 C MR spectra were recorded at 75 or 100 Mz. IR spectra were recorded as a thin film unless otherwise noted. Reactions were monitored by thin layer chromatography (TLC) using silica gel 60 precoated glass plates, 0.25 mm thickness. Components were visualized by illumination with short-wavelength ultra-violet light and/or staining with phosphomolybdic acid solution followed by heating. Flash column chromatography was performed on silica gel 60 (230 400 mesh ATM). C 2 Cl 2 and tetrahydrofuran (TF) were dried by fresh distillation from Ca 2, and a/benzophenone respectively. Tirethylamine was dried by distillation over K. Abbreviations: Acc: 1-Aminoxycyclopropane carboxylic acid; ΔAla: 2-(aminooxy)acrylic acid; AA (Xxx): α-aminoxy acid segment; Xxx represent 3 letter codes for amino acids; Piv: pivaloyl group. S2

II. Synthetic schemes and characterization data of compounds 1 22. Scheme S1. Synthesis of compound 1 starting from L-serine. 2 a Phth b c Me Phth Me Phth Me 33% 86% 59% 10 11 12 d e Me 33% 33% 13 1 Reagents and conditions: a) a 2, KBr, 2 S 4, 0 ºC; Me, Ts, reflux; -hydroxy phthalimide, Et 3, DMF, rt; b) MsCl, Et 3, C 2 Cl 2, rt; c) C 2 2 ; toluene, reflux; d) 2 4 2, Me; Piv, EDCI, At; e) Li, 2 /Me/TF; EDCI, At, iso-butyl amine. Scheme S2. Synthesis of dipeptide 2. D C t Bu a,b 59% D C t Bu c d CMe a 44% D Me e,f 71% 12 D 14 2 Reagents and conditions: a) 2 4 2, Me; b) EDCI, At, iso-butyric acid; c) trifluoroacetic acid, C 2 Cl 2 ; d) EDCI, At, C 2 Cl 2 ; e) Li, Me/ 2 /TF; f) EDCI, At, iso-butyl amine, C 2 Cl 2. S3

Scheme S3. Synthesis of dipeptide 3. CMe c D C t Bu a, b 93% 13 D d 15 e 63% D 3 Reagents and conditions: a) trifluoroacetic acid, C 2 Cl 2 ; b) EDCI, At, iso-butyl amine, C 2 Cl 2 ; c) Li, Me/ 2 /TF; d) 2 4 2, Me; e) EDCI, At, C 2 Cl 2. Scheme S4. Synthesis of dipeptide 4. D C t Bu C t Bu a b c 85% D t Bu a, d 80% D Reagents and conditions: a) trifluoroacetic acid, C 2 Cl 2 ; b) 2 4 2, Me; c) EDCI, At, C 2 Cl 2 ; d) EDCI, At, iso-butyl amine, C 2 Cl 2. 4 S4

Scheme S5. Synthesis of dipeptide 5. C t Bu a,b 83% C t Bu c D C t Bu c,d 83% D a e 76% D 5 Reagents and conditions: a) 2 4 2, Me; b) Pyridine, pivaloyl chloride, C 2 Cl 2, 0ºC; c) trifluoroacetic acid, C 2 Cl 2 ; d) EDCI, At, iso-butyl amine, C 2 Cl 2 ; e) EDCI, At, C 2 Cl 2. Scheme S6. Synthesis of tripeptide 6. D C t Bu a,b 63% D C t Bu CMe a c d 45% D 16 Me 16 e d 52% D 12 Me 12 a e, f 81% 17 D Reagents and conditions: a) 2 4 2, Me; b) EDCI, At, iso-butyric acid, C 2 Cl 2 ; c) trifluoroacetic acid, C 2 Cl 2 ; d) EDCI, At, C 2 Cl 2 ; e) Li, Me/ 2 /TF; f) EDCI, At, iso-butyl amine, C 2 Cl 2. 6 S5

Scheme S7. Synthesis of tetrapeptide 7. C t Bu a, b C t Bu c CMe a d Me e D Me D e, f d e a D 7 D D 82% 73% 55% 71% Me D d 93% a 18 19 20 12 12 12 Reagents and conditions: a) 2 4 2, Me; b) EDCI, At, pivalic acid, C 2 Cl 2 ; c) trifluoroacetic acid, C 2 Cl 2 ; d) EDCI, At, C 2 Cl 2 ; e) Li, Me/ 2 /TF; f) EDCI, At, iso-butyl amine, C 2 Cl 2. Scheme S8. Synthesis of tripeptide 8. Me D C t Bu d a, b c e D D 8 D D 95% 71% 14 Reagents and conditions: a) trifluoroacetic acid, C 2 Cl 2 ; b) EDCI, At, iso-butyl amine, C 2 Cl 2 ; c) 2 4 2, Me; d) Li, Me/ 2 /TF; e) EDCI, At, C 2 Cl 2. S6

Scheme S9. Synthesis of pentapeptide 9. Me D C t Bu a c 9 CMe b c CMe b d D D D D D Me d b D D D 93% c 49% 47% 21 22 14 12 Reagents and conditions: a) trifluoroacetic acid, C 2 Cl 2 ; b) 2 4 2, Me; c) EDCI, At, C 2 Cl 2 ; d) Li, Me/ 2 /TF. S7

Characterization data of compounds 1 22. Phth-Gly- t Bu and Piv-Gly- t Bu, 1 Phth-D-Val- t Bu and Phth-D-leu- t Bu, 2 Piv-D-Leu- t Bu, 3 Phth-D-Leu- i Bu, 4 Phth-L-Val- t Bu, 5 i PrC-D-Leu- t Bu 6 are known compounds. Their preparations were reported in literature. Phth-D-Ser-Me (10). Colorless oil; [α] 20 D +55.5 (c 1.0, CCl 3 ); R f = 0.4 (EtAc:hexane = 1:1); 1 MR (400 Mz, CDCl 3 ) δ 7.90 7.80 (m, 4), 4.76 (dd, J = 4.8, 2.5 z, 1), 4.08 3.92 (m, 2), 3.87 (s, 3); 13 C MR (100 Mz, CDCl 3 ) δ 167.3, 164.3, 135.2, 128.7, 124.2, 85.9, 60.8, 52.9; IR (C 2 Cl 2 ) 3402 (br), 3382, 1672 cm 1 ; EI-MS (20 ev) m/z 148 (100), 266 (M + +1, 1); RMS-EI m/z for C 12 11 6 (M + ) calcd 265.0586, found 265.0612. Phth-ΔAla-Me (11). A white solid. M.p. 126 128 C; R f = 0.3 (EtAc:hexane = 1:4); 1 MR (400 Mz, CDCl 3 ): δ 7.96 7.82 (m, 4), 5.71 (d, J = 3.7 z, 1), 5.07 (d, J = 3.7 z, 1), 3.91 (s, 3); 13 C MR (100 Mz, CDCl 3 ) δ 162.0, 160.6, 150.8, 135.2, 128.8, 124.2, 99.4, 53.0; IR (KBr) 3437, 3124, 1749, 1643 cm 1 ; EI-MS (20 ev) m/z 130 (100), 216 (M + C 3, 4); RMS-EI m/z for C 12 10 5 (M + +1) calcd 248.0559, found 248.0561. Phth-Acc-Me (12). A white solid. M.p. 87 90 C; R f = 0.3 (EtAc:hexane = 1:4); 1 MR (400 Mz, CDCl 3 ) δ 7.88 7.73 (m, 4), 3.80 (s, 3), 1.88 1.84 (m, 2), 1.56 1.50 (m, 2); 13 C MR (100 Mz, CDCl 3 ) δ 171.1, 163.7, 134.8, 129.1, 123.8, 67.7, 52.7, 17.7; IR (KBr) 3441, 3021, 1731 cm 1 ; EI-MS (20 ev) m/z 160 (100), 261 (M +, 1); RMS-EI m/z for C 13 11 5 (M + ) calcd 261.0637, found 261.0633. Piv-Acc-Me (13). Colorless oil. R f = 0.5 (EtAc:hexane = 1:1); 1 MR (400 Mz, CDCl 3 ) δ 9.10 (s, 1), 3.77 (s, 3), 1.65 1.61 (m, 2), 1.38 1.35 (m, 2), 1.20 (s, 9); 13 C MR (100 Mz, CDCl 3 ) δ 176.3, 173.4, 66.2, 52.5, 38.3, 27.3, 16.8; IR (C 2 Cl 2 ) 3385, S8

1744, 1666 cm 1 ; EI-MS (20 ev) m/z 156 (100), 215 (M +, 3); RMS (EI) for C 10 17 4 (M + ): calcd 215.1158, found 215.1156. i PrC-D-Val-Acc-Me (14). Colorless oil; R f = 0.5 (EtAc:hexane = 1:1); [α] 20 D +55.2 (c 1.0, CCl 3 ); 1 MR (300 Mz, CDCl 3 ) δ 11.85 (s, 1), 9.68 (s, 1), 4.09 (d, J = 3.9 z, 1), 3.84 (s, 3), 2.34 2.05 (m, 2), 1.57 1.35 (m, 4), 1.16 1.12 (m, 6), 1.06 (d, J = 6.9 z, 3), 0.95 (d, J = 6.9 z, 3); 13 C MR (75 Mz, CDCl 3 ) δ 177.9, 172.8, 169.0, 91.5, 66.4, 52.9, 32.5, 31.1, 19.7, 19.4, 19.3, 17.2, 17.0, 16.9; IR (C 2 Cl 2 ) 3178 (br), 1740, 1672 cm 1 ; EI-MS (20 ev) m/z 198 (100), 316 (M +, 13); RMS-EI m/z for C 14 24 2 6 (M + ) calcd 316.1634, found 316.1627. Phth-D-Val- i Bu (15). A white solid. M.p. 150 153 C; R f = 0.4 (EtAc:hexane = 1:4); [α] 20 D +128 (c 0.83, C 2 Cl 2 ); 1 MR (400 Mz, CDCl 3 ) δ 7.85 7.76 (m, 4), 7.71 (s, br, 1), 4.63 (d, J = 4.2 z, 1), 3.36 3.29 (m, 1), 2.98 2.91 (m, 1), 2.44 2.44 (m, 1), 1.93 1.85 (m, 1), 1.27 (d, J = 7.4 z, 3), 1.10 (d, J = 6.9 z, 3), 0.99 (d, J = 7.3 z, 3), 0.96 (d, J = 6.9 z, 3); 13 C MR (100 Mz, CDCl 3 ) δ 169.4, 164.2, 135.0, 128.8, 123.9, 92.1, 46.7, 31.5, 28.5, 20.3(2), 19.2, 16.9; IR (C 2 Cl 2 ) 3389, 1742, 1657 cm 1 ; EI-MS (20 ev) m/z 160 (100), 318 (M +, 2); RMS (EI) m/z for C 17 22 2 4 (M + ) calcd 318.1580, found 318.1586. i PrC-D-Leu-Acc-Me (16). Colorless oil. R f = 0.5 (5% acetone in C 2 Cl 2 ); [α] 20 D +37.5 (c 1.0, CCl 3 ); 1 MR (400 Mz, CDCl 3 ) δ 11.57 (s, 1), 9.05 (s, 1), 4.31 4.28 (m, 1), 3.86 (s, 3), 2.34 2.30 (m, 1), 1.95 1.33 (m, 7), 1.17 1.14 (m, 6), 0.97 0.94 (m, 6); 13 C MR (100 Mz, CDCl 3 ) δ 177.6, 172.6, 169.6, 85.4, 66.2, 52.7, 41.0, 32.4, 24.7, 23.3, 21.7, 19.4, 19.1, 16.9(2); IR (C 2 Cl 2 ) 3177 (br), 1738, 1673 cm 1 ; EI-MS (20 ev) m/z 172 (100), 330 (M +, 4); RMS (EI) for C 15 26 2 6 (M + ): calcd 330.1791, found 330.1782. S9

i PrC-D-Leu-Acc-Acc-Me (17). Colorless oil. R f = 0.6 (10% acetone in C 2 Cl 2 ); [α] 20 D +65.1 (c 1.0, CCl 3 ); 1 MR (400 Mz, CDCl 3 ) δ 12.12 (s, 1), 12.04 (s, 1), 9.69 (s, 1), 4.34 (dd, J = 8.2, 5.0 z, 1), 3.84 (s, 3), 2.37 2.30 (m, 1), 1.93 1.37 (m, 11), 1.14 (d, J = 6.8 z, 3), 1.11 (d, J = 6.8 z, 3), 0.95 (d, J = 6.4 z, 3), 0.94 (d, J = 6.9 z, 3); 13 C MR (100 Mz, CDCl 3 ) δ 178.5, 172.7, 171.4, 169.4, 85.3, 67.6, 66.3, 52.6, 40.8, 32.2, 24.6, 23.3, 21.6, 19.3, 19.1, 17.3, 17.0, 16.8, 15.8; IR (C 2 Cl 2 ) 3221, 1735, 1642 cm 1 ; EI-MS (20 ev) m/z 172 (M +, 100), 429 (M +, 16); RMS (EI) for C 19 31 3 8 (M + ): calcd 429.2111, found 429.2115. Piv-D-Leu-Acc-Me (18). Colorless oil. R f = 0.5 (5% acetone in C 2 Cl 2 ); [α] 20 D +39.7 (c 1.0, CCl 3 ); 1 MR (400 Mz, CDCl 3 ) δ 11.40 (s, 1), 8.60 (s, 1), 4.30 (dd, J = 8.7, 3.6 z, 1), 3.86 (s, 3), 1.86 1.24 (m, 7), 1.20 (s, 9), 0.97 (d, J = 6.9 z, 3), 0.95 (d, J = 6.9 z, 3); 13 C MR (100 Mz, CDCl 3 ) δ 179.1, 172.7, 169.2, 85.3, 66.3, 52.7, 41.0, 38.2, 27.2, 27.1, 24.8, 23.3, 21.8, 17.0; IR (C 2 Cl 2 ) 3277, 1751, 1678 cm 1 ; EI-MS (20 ev) m/z 188 (100), 344 (M +, 13); RMS (EI) for C 16 28 2 6 (M + ): calcd 344.1947, found 344.1928. Piv-D-Leu-(Acc) 2 -Me (19). Colorless oil. R f = 0.4 (5% acetone in C 2 Cl 2 ); [α] 20 D +37.8 (c 1.0, CCl 3 ); 1 MR (400 Mz, CDCl 3 ) δ 12.10 (s, 1), 11.99 (s, 1), 9.41 (s, 1), 4.37 (t, J = 6.4 z, 1), 3.85 (s, 3), 1.90 1.35 (m, 11), 1.18 (s, 9), 0.95 (d, J = 6.4 z, 3), 0.94 (d, J = 6.4 z, 3); 13 C MR (100 Mz, CDCl 3 ) δ 179.9, 172.7, 171.3, 169.3, 85.2, 67.6, 66.3, 52.6, 41.0, 38.2, 27.1, 24.6, 23.3, 21.7, 17.3, 17.0, 16.9, 15.6; IR (C 2 Cl 2 ) 3344, 1735, 1632 cm 1 ; EI-MS (20 ev) m/z 186 (100), 443 (M +, 16); RMS (EI) for C 20 33 3 8 (M + ): calcd 443.2268, found 443.2264. Piv-D-Leu-(Acc) 3 -Me (20). Colorless oil. R f = 0.5 (10% acetone in C 2 Cl 2 ); [α] 20 D S10

+35.2 (c 1.0, CCl 3 ); 1 MR (400 Mz, CDCl 3 ) δ 12.16 (s, 1), 12.11 (s, 1), 12.02 (s, 1), 8.74 (s, 1), 4.31 (t, J = 6.4 z, 1), 3.82 (s, 3), 1.85 1.34 (m, 15), 1.21 (s, 9), 0.97 (d, J = 5.9 z, 3), 0.96 (d, J = 6.4 z, 3); 13 C MR (100 Mz, CDCl 3 ) δ 180.5, 172.7, 171.6, 170.7, 169.2, 85.6, 67.8, 67.6, 66.3, 52.6, 40.7, 38.3, 27.1, 24.7, 23.3, 21.7, 17.5, 17.0, 16.9, 16.5, 16.4, 16.3; IR (C 2 Cl 2 ) 3396, 1722, 1628 cm 1 ; EI-MS (20 ev) m/z 145 (100), 542 (M +, 13); RMS (EI) for C 24 38 4 10 (M + ): calcd 542.2588, found 542.2587. Phth-D-Val-Acc-Me (21). A white solid. M.p. 135 139 C; R f = 0.4 (EtAc:hexane = 1:1); [α] 20 D +136.7 (c 1.0, CCl 3 ); 1 MR (300 Mz, CDCl 3 ) δ 10.98 (s, 1), 7.89 7.78 (m, 4), 4.57 (d, J = 4.7 z, 1), 3.90 (s, 3), 2.39 2.36 (m, 2), 1.62 1.61 (m, 1), 1.43 1.34 (m, 2), 1.24 (d, J = 7.0 z, 3), 1.13 (d, J = 7.0 z, 3); 13 C MR (75 Mz, CDCl 3 ) δ 172.5, 167.2, 164.0, 135.0, 128.5, 123.9, 92.1, 66.4, 52.5, 31.5, 18.7, 17.0(2), 16.5; IR (C 2 Cl 2 ) 3252, 1735, 1680 cm 1 ; EI-MS (20 e V) m/z 163 (100), 214 (M + C 8 4 3, 52); RMS (EI) m/z for C 10 16 4 (M + C 8 4 3 ) calcd 214.1079, found 214.1076. i PrC-(D-Val-Acc) 2 -Me (22). Colorless oil. R f = 0.5 (5% acetone in C 2 Cl 2 ); [α] 20 D +90.5 (c 1.0, CCl 3 ); 1 MR (300 Mz, CDCl 3 ) δ 12.14 (s, 1), 12.02 (s, 1), 11.85 (s, 1), 8.45 (s, 1), 4.14 (d, J = 3.8 z, 1), 4.12 (d, J = 3.6 z, 1), 3.81 (s, 3), 2.34 2.30 (m, 3), 1.46 1.26 (m, 8), 1.26 1.06 (m, 12), 0.943 (d, J = 6.9 z, 3), 0.938 (d, J = 7.0 z, 3); 13 C MR (75 Mz, CDCl 3 ) δ 178.5, 172.4, 171.2, 170.8, 168.6, 91.6, 91.1, 67.4, 66.0, 52.4, 32.1, 30.7, 30.6, 19.1, 18.9, 18.8, 18.7, 17.9, 16.8, 16.6, 16.1, 15.9, 15.1; IR (C 2 Cl 2 ) 3186, 1740, 1671 cm 1 ; EI-MS (20 ev) m/z 110 (100), 530 (M +, 32); RMS (EI) m/z for C 23 38 4 10 (M + ) calcd 530.2588, found 530.2581. S11

III. 1 MR experimental result of compound 1. a) δ (ppm) 9.2 9.0 8.8 8.6 8.4 8.2 8.0 7.8 b a a b 1 b) 10.5 10.0 9.5 9.0 8.5 8.0 δ (ppm) a 1 b a b 7.6-3.5-3.0-2.5-2.0-1.5-1.0-0.5 Log Conc. 7.5 0 10 20 30 40 volume of DMS-d 6 added (μl) Figure S1. (a) Chemical shifts of amide protons as a function of the logarithm of the concentration of compound 1 in CDCl 3 at room temperature; (b) Chemical shifts of amide protons as a function of the amount of DMS-d 6 added in a solution of compound 1 in 5 mm CDCl 3. S12

IV. Theoretical study results: energies and Cartesian coordinates for models I IV All the calculations were performed with Gaussian03 7 software package. All of the molecules were full optimized using B3LYP 8 /6-311+G** followed by harmonic vibration frequency calculations to ensure that each structure was a minimum. Energies were evaluated by MP2 9 /6-311+G** calculations on B3LYP/6-311+G** geometries. Solvent effect was evaluated by the PCM 10 model using B3LYP/6-311+G** method. The relative free energies of conformers were calculated with the MP2/6-311+G** energies plus the enthalpy and entropy corrections along with the solvent energy corrections as shown in Eq. 1. ΔG = ΔE (MP2) + [ΔE (B3LYP, solvent) ΔE (B3LYP, gas)]+ enthalpy corrections TΔS (Eq. 1) S13

Table S1. Calculated energies and corrections of models I IV. (S) I Me (S) II Me Me Me III IV Gas phase Solvent ΔG (C 2 Cl 2 ) Enthalpy Entropy MP2/6-311+G(d, p) B3LYP/ MP2/ B3LYP/ correction correction (Gas phase) (C 2 Cl 2 ) 6-311+G** 6-311+G** 6-311+G** (hartree) (hartree) (Kcal/mol) (Kcal/mol) (hartree) (hartree) (hartree) Ia -931.857252-929.3426133-931.880598 0.302607 0.230910 0.0 0.0 Ib -931.855581-929.3411815-931.878571 0.302552 0.231073 1.0 1.2 IIa -931.856466-929.3410583-931.880291 0.302619 0.230813 0 0 IIb -931.855629-929.3413895-931.878257 0.302534 0.231019-0.1 0.7 IIIa -609.270777-607.6049929-609.288545 0.208631 0.153542 0.0 0.0 IIIb -609.270777-607.6049947-609.288541 0.208631 0.153555 0.0 0.0 IIIc -609.262949-607.5967318-609.281689 0.208361 0.151162 3.7 3.1 IIId -609.265813-607.6002545-609.285166 0.208565 0.153066 2.7 1.7 IVa -684.288538-682.6080995-684.464408 0.213302 0.156401 0.0 0.0 IVb -684.288540-682.6080955-684.464414 0.213301 0.156395 0.0 0.0 IVc -684.282197-682.6003148-684.457081 0.213118 0.154908 3.9 4.5 IVd -684.284269-682.6024094-684.461317 0.213043 0.154784 2.6 1.8 S14

Table S2. Geometries (Cartesian coordinates) of models I IV optimized using B3LYP/6-311+G** 1. Ac-L-Ala-Acc-Me, Ia and Ib (1) Ia --------------------------------------------------------------------- 1 6 0-4.706925-1.562500-0.664555 2 6 0-3.453665-0.971694-0.058999 3 7 0-3.436711 0.408737-0.030961 4 8 0-2.522312 1.015800 0.833177 5 6 0-1.608490 1.907364 0.146776 6 6 0-1.136952 2.911204 1.191649 7 8 0-2.520070-1.648911 0.331959 8 6 0-0.405163 1.205654-0.505539 9 8 0 0.294868 1.832114-1.289373 10 7 0-0.162003-0.054943-0.073654 11 8 0 0.755798-0.812474-0.819033 12 6 0 1.838726-1.288820-0.030808 13 6 0 2.143608-2.749842-0.259331 14 6 0 1.534780-2.304618 1.040683 15 6 0 3.018488-0.360589 0.159304 16 8 0 3.963373-0.702458 0.865486 17 7 0 2.967314 0.811192-0.507811 18 6 0 4.050617 1.775688-0.408048 19 1 0-5.359068-0.818176-1.124928 20 1 0 4.967297 1.389811-0.862726 21 1 0-4.329100 0.890100-0.014996 22 1 0-2.144261 2.410755-0.662229 23 1 0-0.921230-0.624968 0.310778 24 1 0 2.140633 1.051551-1.046318 25 1 0 3.751055 2.686290-0.926685 26 1 0 4.269069 2.009178 0.636836 27 1 0-4.416072-2.299197-1.413996 28 1 0-5.258427-2.084130 0.121746 29 1 0-1.982542 3.491352 1.565105 30 1 0-0.665456 2.394834 2.030592 31 1 0-0.409538 3.587289 0.741238 32 1 0 1.503822-3.254867-0.971924 33 1 0 3.189952-3.025231-0.268111 34 1 0 0.489576-2.530983 1.212467 35 1 0 2.170695-2.272164 1.915602 --------------------------------------------------------------------- S15

(2) Ib --------------------------------------------------------------------- 1 C 0 2.932062-2.700432 1.526397 2 C 0 2.550008-1.669494 0.488370 3 0 1.974483-1.946480-0.547849 4 0 2.862352-0.370184 0.841765 5 0 2.881508 0.568061-0.193857 6 C 0 2.046765 1.722136 0.068319 7 C 0 0.561590 1.538617-0.291545 8 0 0.218842 0.340192-0.802898 9 0-1.033901 0.206460-1.409093 10 C 0-1.881592-0.741377-0.765240 11 C 0-2.707488-0.264109 0.410726 12 0-2.636501 1.050043 0.702245 13 C 0-3.391145 1.607880 1.812937 14 C 0 2.643902 2.862299-0.747766 15 0-0.212543 2.468185-0.095161 16 C 0-2.559389-1.675392-1.739467 17 C 0-1.486999-2.195915-0.825186 18 0-3.418658-1.060072 1.019610 19 0 3.317513-2.264989 2.450025 20 0-3.115954 1.132745 2.758823 21 0 3.648160-0.235998 1.469336 22 0 2.084007 1.950649 1.137299 23 0 0.899166-0.380748-1.047589 24 0-1.972302 1.643488 0.212479 25 0-3.178839 2.675155 1.872031 26 0-4.464044 1.461951 1.666389 27 0 2.052564-3.303600 1.755203 28 0 3.688820-3.361396 1.096993 29 0 3.660622 3.071737-0.411223 30 0 2.672577 2.597309-1.807230 31 0 2.029487 3.754002-0.626273 32 0-0.516258-2.424803-1.245884 33 0-1.794870-2.796350 0.020923 34 0-2.308730-1.524194-2.781878 35 0-3.588167-1.929824-1.521669 --------------------------------------------------------------------- S16

2. Ac-Acc-L-Ala-Me, IIa and IIb (1) IIa --------------------------------------------------------------------- 1 6 0-4.510787-2.043328-0.388140 2 6 0-3.250612-1.382565 0.124963 3 7 0-3.295423-0.004197 0.119728 4 8 0-2.355994 0.670312 0.917507 5 6 0-1.496300 1.520659 0.170050 6 6 0-1.355920 2.903552 0.763604 7 6 0-2.102109 2.712295-0.525526 8 8 0-2.264977-2.009196 0.469601 9 6 0-0.246327 0.909309-0.420095 10 8 0 0.471813 1.567580-1.163320 11 7 0 0.032733-0.348536 0.009562 12 8 0 1.006860-1.052376-0.700649 13 6 0 2.080128-1.523005 0.152700 14 6 0 3.173226-0.475626 0.426996 15 8 0 4.033025-0.726009 1.265258 16 6 0 2.670847-2.739233-0.550361 17 7 0 3.145666 0.645506-0.320739 18 6 0 4.129885 1.698626-0.127176 19 1 0-5.230052-1.339662-0.810915 20 1 0 5.137189 1.279515-0.144938 21 1 0-4.203242 0.442167 0.170446 22 1 0-0.714955-0.955401 0.362079 23 1 0 2.330411 0.836754-0.896604 24 1 0 4.026034 2.425081-0.933110 25 1 0 3.995184 2.207428 0.832918 26 1 0-4.233606-2.774610-1.148063 27 1 0-4.979853-2.581349 0.439432 28 1 0 1.660988-1.807960 1.121094 29 1 0 3.516405-3.112397 0.028212 30 1 0 1.918776-3.524987-0.641428 31 1 0 3.020202-2.469325-1.549996 32 1 0-1.928111 3.082758 1.665009 33 1 0-0.369794 3.347173 0.726338 34 1 0-3.182113 2.790821-0.503891 35 1 0-1.622303 3.017993-1.445707 --------------------------------------------------------------------- S17

(2) IIb --------------------------------------------------------------------- 1 C 0-3.236057 1.319414-1.775589 2 C 0-2.125862 0.953979-0.798359 3 0-1.276963 0.011839-1.504042 4 0-0.000988-0.062905-0.957331 5 C 0 0.444201-1.264124-0.525739 6 C 0 1.926236-1.328601-0.238548 7 0 2.696380-0.156257-0.459135 8 0 2.638524 0.750334 0.614078 9 C 0 2.227632 2.034348 0.314840 10 C 0 2.561563 3.052056 1.382978 11 C 0-2.716773 0.414370 0.515056 12 0-3.249672 1.203420 1.288847 13 0-2.662903-0.918811 0.706554 14 C 0-3.185488-1.522649 1.922264 15 0-0.263721-2.251971-0.360165 16 C 0 2.409154-2.310082 0.800613 17 C 0 2.638414-2.592546-0.656764 18 0 1.605700 2.307535-0.695239 19 0-4.197511-1.163106 2.113642 20 0 0.625848 0.698012-1.225213 21 0-2.075055-1.482375 0.098218 22 0-3.203782-2.604821 1.793858 23 0-2.570251-1.276671 2.794099 24 0-1.535067 1.837788-0.544204 25 0-3.933026 2.002148-1.288314 26 0-2.817038 1.802780-2.659920 27 0-3.779326 0.424329-2.087818 28 0 3.260193-2.007529 1.398680 29 0 1.643762-2.874771 1.316406 30 0 3.636474-2.454319-1.052620 31 0 2.030795-3.350187-1.133145 32 0 3.435453 0.639803 1.230086 33 0 3.006933 2.614169 2.278063 34 0 3.251831 3.785350 0.959129 35 0 1.645409 3.575563 1.659313 --------------------------------------------------------------------- S18

3. Ac-Acc-Me, IIIa d (1) IIIa --------------------------------------------------------------------- 1 6 0-3.620757-0.186424 0.693956 2 6 0-2.323623 0.063082-0.047450 3 8 0-2.117088 1.067567-0.702941 4 7 0-1.380901-0.926352 0.130498 5 8 0-0.321168-0.975683-0.788362 6 6 0 0.955649-0.893371-0.164453 7 6 0 1.487119 0.483467 0.177432 8 8 0 2.555101 0.592108 0.773540 9 6 0 1.946737-1.887078-0.719066 10 7 0 0.749122 1.530990-0.239507 11 6 0 1.169032 2.896318 0.035972 12 1 0-3.581902-1.047465 1.363890 13 1 0-3.867141 0.705675 1.270748 14 1 0-4.415095-0.340267-0.040646 15 1 0-1.704299-1.855066 0.373325 16 6 0 1.404430-2.064297 0.672004 17 1 0 2.125213 3.115595-0.445517 18 1 0 0.408848 3.574976-0.349897 19 1 0 1.288868 3.061498 1.109877 20 1 0-0.152030 1.372740-0.680290 21 1 0 2.964542-1.537462-0.829938 22 1 0 1.572938-2.539024-1.498505 23 1 0 0.684116-2.856997 0.835716 24 1 0 2.052106-1.828793 1.506045 --------------------------------------------------------------------- (2) IIIb --------------------------------------------------------------------- 1 6 0 3.620810-0.187025 0.693835 2 6 0 2.323708 0.062737-0.047535 3 7 0 1.380467-0.926104 0.131327 4 8 0 0.320998-0.975922-0.787804 5 6 0-0.956016-0.893182-0.164349 6 6 0-1.946961-1.886838-0.719270 7 6 0-1.405357-2.064020 0.672031 8 8 0 2.117662 1.066693-0.703950 9 6 0-1.487245 0.483772 0.177196 10 7 0-0.747918 1.531030-0.237994 S19

11 6 0-1.168037 2.896548 0.036158 12 8 0-2.555858 0.592821 0.772120 13 1 0 3.870080 0.706835 1.266604 14 1 0 3.580132-1.045169 1.367368 15 1 0 4.414131-0.346224-0.040760 16 1 0 1.703505-1.854715 0.375066 17 1 0 0.152307 1.372437-0.680511 18 1 0-2.115970 3.121506-0.459113 19 1 0-1.304041 3.057042 1.108729 20 1 0-0.399710 3.574294-0.334889 21 1 0-0.685190-2.856754 0.836230 22 1 0-2.053378-1.828387 1.505772 23 1 0-1.572849-2.538877-1.498487 24 1 0-2.964689-1.537166-0.830673 --------------------------------------------------------------------- (3) IIIc --------------------------------------------------------------------- 1 6 0 3.474324-1.456509 0.516901 2 6 0 2.635919-0.257683 0.107849 3 7 0 1.411455-0.601444-0.392144 4 8 0 0.634016 0.361527-1.028203 5 6 0-0.495742 0.716601-0.263258 6 6 0-0.843171 2.174614-0.403677 7 8 0 3.014655 0.892046 0.239134 8 6 0-1.523677-0.392181-0.193308 9 7 0-2.736227-0.085799 0.343329 10 6 0-3.789720-1.086614 0.454643 11 8 0-1.249340-1.523285-0.575422 12 1 0 3.826187-1.301413 1.537711 13 1 0 2.939026-2.406394 0.460132 14 1 0 4.349349-1.502871-0.135611 15 1 0 1.113200-1.542266-0.611933 16 6 0-0.259630 1.669820 0.889317 17 1 0-2.962470 0.872027 0.552647 18 1 0-3.387159-1.999089 0.895154 19 1 0-4.578873-0.695760 1.097249 20 1 0-4.212981-1.338123-0.522200 21 1 0-0.189508 2.738266-1.057144 22 1 0-1.887907 2.459019-0.455339 23 1 0 0.780050 1.898722 1.087394 S20

24 1 0-0.899974 1.577986 1.758757 --------------------------------------------------------------------- (4) IIId --------------------------------------------------------------------- 1 6 0 3.458962-1.475359 0.619012 2 6 0 2.584589-0.400186-0.000710 3 8 0 3.008287 0.673096-0.370405 4 7 0 1.245700-0.745568-0.048965 5 8 0 0.412687 0.006936-0.889320 6 6 0-0.514422 0.797743-0.154637 7 6 0-1.788768 0.096152 0.245946 8 8 0-2.574115 0.591452 1.040155 9 6 0-0.615675 2.230109-0.628349 10 7 0-1.988975-1.113487-0.354736 11 6 0-3.235299-1.845917-0.182717 12 1 0 4.059783-1.020437 1.407308 13 1 0 2.896300-2.312654 1.036774 14 1 0 4.141367-1.849914-0.147831 15 1 0 0.984525-1.723327-0.036709 16 6 0 0.014580 1.915767 0.698827 17 1 0-1.397116-1.332449-1.142205 18 1 0-3.554063-1.763196 0.855520 19 1 0-4.035736-1.450562-0.817146 20 1 0-3.072576-2.896758-0.426329 21 1 0-0.549504 2.129789 1.597201 22 1 0 1.092325 1.989226 0.761306 23 1 0 0.044532 2.493796-1.444863 24 1 0-1.605574 2.668150-0.644799 --------------------------------------------------------------------- S21

4. Ac-Acc-Me IVa d a) IIIa 0.0 (0.0) IIIb 0.0 (0.0) IIIc 3.7 (3.1) IIId 2.7 (1.7) b) IVa 0.0 (0.0) IVb 0.0 (0.0) IVc 3.9 (4.5) IVd 2.6 (1.8) Figure S2. Calculated structures of model a) Ac-Acc-Me III and b) Ac-Acc-Me IV and their relative energies at MP2/6-311+G** level in vacuum and in C 2 Cl 2 (in bracket). (1) IVa --------------------------------------------------------------------- 1 C 0 3.664086-1.155474 0.615710 2 C 0 2.333583-0.870733-0.047385 3 0 1.656087-1.734046-0.573673 4 0 1.931282 0.444891 0.044131 5 0 0.928045 0.870150-0.841537 6 C 0-0.222034 1.372605-0.171595 7 C 0-1.258862 0.373889 0.301193 8 0-2.201973 0.736830 0.985550 9 C 0-0.086136 2.665777 0.589190 10 C 0-0.739709 2.660970-0.764312 11 0-1.094000-0.888749-0.181120 12 0-1.862912-1.904294 0.381359 13 0 4.065654-0.305680 1.170725 S22

14 0 3.538137-2.000041 1.294042 15 0 4.379240-1.449677-0.156405 16 0 2.643913 1.154967 0.161878 17 0-0.192881-1.226679-0.523897 18 0-1.815119 2.770141-0.814158 19 0-0.178004 3.049217-1.604559 20 0 0.910086 3.083842 0.667836 21 0-0.717283 2.770280 1.461697 22 C 0-3.096646-2.065876-0.330304 23 0-3.595780-2.901957 0.160244 24 0-3.710107-1.166262-0.246089 25 0-2.908503-2.307205-1.380959 --------------------------------------------------------------------- (2) IVb --------------------------------------------------------------------- 1 C 0-3.664319-1.155243 0.615353 2 C 0-2.333554-0.870569-0.047231 3 0-1.931252 0.445089 0.044354 4 0-0.928001 0.870306-0.841373 5 C 0 0.222130 1.372601-0.171480 6 C 0 0.086639 2.666042 0.588937 7 C 0 0.740240 2.660655-0.764549 8 0-1.655976-1.733834-0.573492 9 C 0 1.258701 0.373748 0.301533 10 0 1.093708-0.888845-0.180885 11 0 1.862715-1.904469 0.381326 12 C 0 3.096276-2.066163-0.330577 13 0 2.201987 0.736618 0.985705 14 0-3.539198-2.001127 1.292168 15 0-4.065069-0.306001 1.171811 16 0-4.379775-1.447391-0.157291 17 0-2.644007 1.155112 0.161752 18 0 0.192459-1.226689-0.523519 19 0-0.909478 3.084428 0.667280 20 0 0.717712 2.770627 1.461484 21 0 0.178655 3.048850-1.604912 22 0 1.815677 2.769459-0.814476 23 0 3.595616-2.902102 0.160005 24 0 2.907935-2.307716-1.381141 25 0 3.709794-1.166543-0.246696 --------------------------------------------------------------------- S23

(3) IVc --------------------------------------------------------------------- 1 C 0 3.723161-1.682498 0.506460 2 C 0 2.968527-0.430830 0.095392 3 0 3.434570 0.688571 0.192457 4 0 1.699196-0.686061-0.355280 5 0 1.009801 0.321656-1.028657 6 C 0-0.065334 0.820611-0.269415 7 C 0 0.282600 1.793421 0.839922 8 C 0-0.274440 2.299667-0.462857 9 C 0-1.198551-0.172873-0.153407 10 0-1.082870-1.321082-0.533842 11 0-2.385047 0.327517 0.354109 12 0-3.312302-0.600686 0.835632 13 0 4.126598-1.531344 1.508480 14 0 3.111091-2.586457 0.496979 15 0 4.565066-1.815900-0.177078 16 0 1.364059-1.606093-0.607929 17 0-2.361571 1.133363 0.964575 18 0 0.418117 2.771380-1.148383 19 0-1.292157 2.667130-0.511499 20 0 1.344324 1.920861 1.010684 21 0-0.337846 1.806559 1.729201 22 C 0-4.267936-0.936717-0.180698 23 0-4.960819-1.623188 0.306084 24 0-4.800537-0.043965-0.521320 25 0-3.777125-1.434908-1.018704 --------------------------------------------------------------------- (4) IVd --------------------------------------------------------------------- 1 C 0 3.670258-1.698675 0.575557 2 C 0 2.871273-0.571078-0.051582 3 0 1.505385-0.790727-0.027023 4 0 0.708472 0.005287-0.863272 5 C 0-0.101116 0.909926-0.123790 6 C 0 0.567500 2.012661 0.648321 7 C 0-0.103494 2.323500-0.659447 8 0 3.372500 0.443089-0.485913 9 C 0-1.404232 0.344136 0.383499 10 0-1.700221-0.884153-0.152067 S24

11 0-2.883911-1.526947 0.162056 12 0-2.110938 0.927259 1.183514 13 0 4.354068-1.271403 1.309798 14 0 3.052577-2.456983 1.060818 15 0 4.270632-2.172266-0.205080 16 0 1.151906-1.736899 0.040890 17 0-1.259979-1.194883-1.008965 18 0 0.073693 2.315385 1.562497 19 0 1.649320 1.988687 0.654736 20 0 0.531012 2.489933-1.520747 21 0-1.050419 2.848304-0.647222 22 C 0-4.024895-0.909585-0.463547 23 0-4.873883-1.519879-0.156784 24 0-4.150090 0.113582-0.107320 25 0-3.925722-0.934236-1.554138 --------------------------------------------------------------------- S25

V. CD spectra of oligopeptides 2 9. D a b D a c D a 2 3 b c b D a 4 5 b c c a D b c d a b 6 7 D c d e a D D D D D b c d a b c d e 8 9 f a) Mol.Ellip. (deg cm 2 dmol 1 ) 100000 80000 60000 40000 20000 dipeptide 2 4mM dipeptide 2 1mM dipeptide 2 0.4mM b) Mol.Ellip. (deg cm 2 dmol 1 ) 100000 80000 60000 40000 20000 dipeptide 3 4mM dipeptide 3 1mM dipeptide 3 0.4mM 0 190 200 210 220 230 240 250 wavelength (nm) 0 190 200 210 220 230 240 250 wavelength (nm) c) Mol.Ellip. (deg cm 2 dmol 1 ) 80000 70000 60000 50000 40000 30000 20000 10000 dipeptide 5 4 mm dipeptide 5 1 mm dipeptide 5 0.4 mm d) Mol.Ellip. (deg cm 2 dmol 1 ) 40000 30000 20000 10000 dipeptide 6 4 mm dipeptide 6 1 mm dipeptide 6 0.4 mm 0-10000 190 200 210 220 230 240 250 wavelength (nm) 0 190 200 210 220 230 240 250 wavelength (nm) S26

e) Mol.Ellip. (deg cm 2 dmol 1 ) 100000 80000 60000 40000 20000 tripeptide 6 4mM tripeptide 6 1mM tripeptide 6 0.4mM f) Mol.Ellip. (deg cm 2 dmol 1 ) 100000 80000 60000 40000 20000 tetrapeptide 7 tetrapeptide 7 tetrapeptide 7 4mM 1mM 0.4mM 0 0 190 200 210 220 230 240 250 wavelength (nm) 190 200 210 220 230 240 250 wavelength (nm) g) Mol.Ellip. (deg cm 2 dmol 1 ) 60000 50000 40000 30000 20000 10000 0 tripeptide 8 4mM tripeptide 8 1mM tripeptide 8 0.4mM h) Mol.Ellip. (deg cm 2 dmol 1 ) 60000 50000 40000 30000 20000 10000 0 pentapeptide 9 pentapeptide 9 pentapeptide 9 4 mm 1 mm 0.4 mm -10000 190 200 210 220 230 240 250 wavelength (nm) -10000 190 200 210 220 230 240 250 wavelength (nm) Figure S3. Circular dichroism spectra of oligopeptides at different concentration in trifluoroethanol. The spectra of 2 7 (figures a f) have been normalized for the concentration only, whereas those of 8 and 9 (figures g and h) have been normalized for both the concentration and the number of potential maximum turns. S27

Mol.Ellip. (deg cm 2 dmol 1 ) 50000 40000 30000 20000 10000 0 dipeptide 2 dipeptide 3 tripeptide 6 tetrapeptide 7 tripeptide 8 pentapeptide 9 190 200 210 220 230 240 250 wavelength (nm) Figure S4. Circular dichroism spectra of oligopeptides 2, 3, and 6 9 at 4 mm concentration in methanol (after normalization for both the concentration and the number of potential maximum turns). References: (1) Yang, D.; g, F.-F.; Li, Z.-J. J. Am. Chem. Soc. 1996, 118, 9794. (2) Yang, D.; Li, B.; g, F.-F.; Yan, Y.-L.; Qu, J.; Wu, Y.-D. J. rg. Chem. 2001, 66, 7303. (3) Yang, D.; Qu, J.; Li, B.; g, F.-F.; Wang, X.-C.; Cheung, K.-K.; Wang, D.-P.; Wu, Y.-D. J. Am. Chem. Soc. 1999, 121, 589. (4) Li, X.; Shen, B.; Yao, X.; Yang, D. J. Am. Chem. Soc. 2007, 129, 7264. (5) Yang, D.; Li, W.; Qu, J.; Luo, S.-W.; Wu, Y.-D. J. Am. Chem. Soc. 2003, 125, 13018. (6) Yang, D.; Liu, G.-J.; Jiao, Z.-G.; Zhang, D.-W.; Luo, Z.; Song, K.-S.; Chen, M.-Q. Chem. Eur. J. 2008, 14, 10297. (7) Frisch, M. J.; Trucks, G. W.; Schlegel,. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, Jr., T.; Kudin, K..; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega,.; Petersson, G. A.; akatsuji,.; ada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; asegawa, J.; Ishida, M.; akajima, T.; onda, Y.; Kitao,.; akai,.; Klene, M.; Li, X.; Knox, J. E.; ratchian,. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,.; Austin, A. J.; Cammi, R.; Pomelli, C.; chterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; rtiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; S28

Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; anayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, revision B05, Gaussian, Inc.: Pittsburgh, PA, 2003. (8) (a) Becke, A.D. J. Chem. Phys. 1993, 98, 5648. (b) Miehlich, B.; Savin, A.; Stoll,.; Preuss,. Chem. Phys. Lett. 1989, 157, 200. (c) Lee, C.; Yang, W.; Parr, G. Phys. Rev. B 1988, 37, 785. (9) (a) Moller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618. (b) andy,. C.; Schaefer, III,. F. J. Chem. Phys. 1984, 81, 5031. (c) ead-gordon, M.; ead-gordon, T. Chem. Phys. Lett. 1994, 220, 122. (10) (a) Cances, M. T.; Mennucci, B.; Tomasi, J. J. Chem. Phys. 1997, 107, 3032. (b) Cossi, M.; Barone, V.; Mennucci, B.; Tomasi, J. Chem. Phys. Lett. 1998, 286, 253. (c) Mennucci, B.; Tomasi, J. J. Chem. Phys. 1997, 106, 5151. (d) Cossi, M.; Scalmani, G.; Rega,.; Barone, V. J. Chem. Phys. 2002, 117, 43. S29

VI. X-Ray data of compounds 1, 2 and 8. 1 Figure S5. Twinned structure and -bond in the crystal of compound 1. Table S3. Intramolecular -bond length (Å) and dihedral angle values ( ) of the backbone of dipeptide 2 D a b 2 c φ θ ψ Compound D (Å) ( ) φ ( ) θ ( ) ψ ( ) 2 D-Val 1.99 153.1 124.7 83.2 1.2 Acc 2.04 154.2 121.0 85.5 2.2 S30

Table S4 Crystal data and structure refinement for compound 1. Empirical formula C 13 24 2 3 Formula weight 256.34 Temperature 253(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group C 2/c Unit cell dimensions a = 37.348(8) Å α= 90. b = 8.973(2) Å β= 127.48(3). c = 23.854(5) Å γ = 90. Volume Z 16 6343(2) Å3 Density (calculated) 1.074 Mg/m 3 Absorption coefficient 0.076 mm -1 F(000) 2240 Crystal size 0.4 x 0.3 x 0.2 mm 3 Theta range for data collection 1.71 to 23.97. Index ranges -39<=h<=35, -8<=k<=8, -27<=l<=27 Reflections collected 7354 Independent reflections 2839 [R(int) = 0.0541] Completeness to theta = 23.97 57.2 % Absorption correction one Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 2839 / 7 / 370 Goodness-of-fit on F 2 0.945 Final R indices [I>2sigma(I)] R1 = 0.0579, wr2 = 0.1385 R indices (all data) R1 = 0.1106, wr2 = 0.1526 Largest diff. peak and hole 0.213 and -0.173 e.å-3 S31

Table S5 Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters (Å 2 x 10 3 ) for compound 1. U(eq) is defined as one third of the trace of the orthogonalized U ij tensor. x y z U(eq) (1) 7103(1) -1978(4) 540(2) 85(1) (2) 6211(1) -1928(3) -371(2) 62(1) (3) 6032(1) 208(4) -1804(2) 87(1) (1) 6449(2) -1080(4) 258(2) 58(1) (2) 6636(2) -1102(5) -916(2) 65(1) C(1) 5976(2) -987(6) -974(3) 58(1) C(2) 5485(2) -1375(7) -1493(3) 91(2) C(3) 5626(2) 6(6) -1073(3) 88(2) C(4) 6217(2) -563(6) -1268(3) 58(2) C(5) 6899(2) -1316(6) 716(3) 61(2) C(6) 7125(2) -681(6) 1442(3) 75(2) C(7) 7056(3) -1808(7) 1856(3) 147(3) C(8) 7620(2) -464(9) 1791(3) 174(4) C(9) 6915(2) 783(7) 1433(3) 120(2) C(10) 6907(2) -882(6) -1157(3) 83(2) C(11) 7213(3) 442(7) -833(4) 103(2) C(12) 7578(2) 279(7) -54(4) 133(3) C(13) 7433(3) 689(8) -1209(4) 168(3) (4) 5335(1) -4431(4) 1469(2) 83(1) (5) 5347(1) -1481(3) 1437(2) 60(1) (6) 5825(1) -828(4) 521(2) 71(1) (3) 5669(2) -2305(5) 2055(2) 61(1) (4) 5507(2) -2915(5) 591(2) 61(1) C(14) 5556(2) -687(5) 1193(2) 51(1) C(15) 5392(2) 885(5) 990(3) 69(2) C(16) 5856(2) 572(5) 1637(3) 66(2) C(17) 5642(2) -1505(7) 742(2) 56(2) C(18) 5601(2) -3784(7) 2027(3) 60(2) C(19) 5888(2) -4581(6) 2731(3) 73(2) C(20) 5637(12) -4290(40) 3060(15) 179(14) C(21) 6371(10) -3940(30) 3271(14) 172(16) C(22) 5957(11) -6160(30) 2610(12) 133(12) C(20') 5910(20) -4090(60) 3310(20) 240(40) C(21') 6358(11) -4490(70) 2970(20) 230(30) S32

C(22') 5691(16) -6120(40) 2600(20) 170(20) C(23) 5560(2) -3849(5) 147(2) 74(2) C(24) 5799(2) -5287(7) 502(4) 107(2) C(25) 6238(2) -5181(8) 1171(4) 157(3) C(26) 5800(2) -6271(7) -28(3) 151(3) S33

Table S6 Bond lengths [Å] and angles [ ] for compound 1. (1)-C(5) 1.226(6) (2)-(1) 1.414(4) (2)-C(1) 1.418(5) (3)-C(4) 1.232(6) (1)-C(5) 1.351(6) (2)-C(4) 1.337(6) (2)-C(10) 1.449(6) C(1)-C(3) 1.478(7) C(1)-C(4) 1.489(7) C(1)-C(2) 1.501(7) C(2)-C(3) 1.475(6) C(5)-C(6) 1.502(7) C(6)-C(8) 1.507(7) C(6)-C(9) 1.524(7) C(6)-C(7) 1.542(7) C(10)-C(11) 1.497(7) C(11)-C(12) 1.500(7) C(11)-C(13) 1.558(7) (4)-C(18) 1.219(5) (5)-C(14) 1.416(5) (5)-(3) 1.418(4) (6)-C(17) 1.247(6) (3)-C(18) 1.345(6) (4)-C(17) 1.329(6) (4)-C(23) 1.455(5) C(14)-C(16) 1.486(6) C(14)-C(17) 1.490(6) C(14)-C(15) 1.496(6) C(15)-C(16) 1.485(6) C(18)-C(19) 1.513(7) C(19)-C(20') 1.39(4) C(19)-C(21') 1.49(4) C(19)-C(22) 1.50(2) C(19)-C(22') 1.51(4) C(19)-C(21) 1.56(3) C(19)-C(20) 1.57(3) C(23)-C(24) 1.504(7) C(24)-C(25) 1.435(7) C(24)-C(26) 1.544(7) S34

(1)-(2)-C(1) 111.0(3) C(5)-(1)-(2) 116.3(4) C(4)-(2)-C(10) 122.3(5) (2)-C(1)-C(3) 117.5(4) (2)-C(1)-C(4) 116.8(5) C(3)-C(1)-C(4) 120.0(5) (2)-C(1)-C(2) 112.9(5) C(3)-C(1)-C(2) 59.3(3) C(4)-C(1)-C(2) 117.2(5) C(3)-C(2)-C(1) 59.6(3) C(2)-C(3)-C(1) 61.1(3) (3)-C(4)-(2) 123.9(6) (3)-C(4)-C(1) 121.0(6) (2)-C(4)-C(1) 115.1(5) (1)-C(5)-(1) 121.7(5) (1)-C(5)-C(6) 123.2(6) (1)-C(5)-C(6) 115.1(5) C(5)-C(6)-C(8) 109.1(5) C(5)-C(6)-C(9) 112.7(5) C(8)-C(6)-C(9) 110.2(5) C(5)-C(6)-C(7) 107.0(5) C(8)-C(6)-C(7) 111.0(5) C(9)-C(6)-C(7) 106.7(5) (2)-C(10)-C(11) 113.7(5) C(10)-C(11)-C(12) 113.4(5) C(10)-C(11)-C(13) 108.7(6) C(12)-C(11)-C(13) 109.0(6) C(14)-(5)-(3) 111.1(3) C(18)-(3)-(5) 116.6(4) C(17)-(4)-C(23) 123.3(5) (5)-C(14)-C(16) 117.0(4) (5)-C(14)-C(17) 117.6(4) C(16)-C(14)-C(17) 119.3(5) (5)-C(14)-C(15) 112.9(4) C(16)-C(14)-C(15) 59.7(3) C(17)-C(14)-C(15) 117.1(4) C(16)-C(15)-C(14) 59.8(3) C(15)-C(16)-C(14) 60.5(3) (6)-C(17)-(4) 124.4(5) (6)-C(17)-C(14) 118.7(5) (4)-C(17)-C(14) 116.9(5) S35

(4)-C(18)-(3) 121.9(5) (4)-C(18)-C(19) 122.9(5) (3)-C(18)-C(19) 115.2(6) C(20')-C(19)-C(21') 105(3) C(20')-C(19)-C(22) 125(2) C(21')-C(19)-C(22) 80(2) C(20')-C(19)-C(22') 103(3) C(21')-C(19)-C(22') 116(2) C(22)-C(19)-C(22') 37.8(17) C(20')-C(19)-C(18) 121.6(17) C(21')-C(19)-C(18) 105.6(15) C(22)-C(19)-C(18) 108.8(10) C(22')-C(19)-C(18) 106.0(14) C(20')-C(19)-C(21) 74(3) C(21')-C(19)-C(21) 33(3) C(22)-C(19)-C(21) 105.0(15) C(22')-C(19)-C(21) 133.2(18) C(18)-C(19)-C(21) 115.2(10) C(20')-C(19)-C(20) 32(3) C(21')-C(19)-C(20) 137(2) C(22)-C(19)-C(20) 118.6(17) C(22')-C(19)-C(20) 84(2) C(18)-C(19)-C(20) 103.9(11) C(21)-C(19)-C(20) 106(2) (4)-C(23)-C(24) 112.5(4) C(25)-C(24)-C(23) 117.1(5) C(25)-C(24)-C(26) 112.2(6) C(23)-C(24)-C(26) 109.1(5) Symmetry transformations used to generate equivalent atoms: S36

Table S7 Anisotropic displacement parameters (Å 2 x 10 3 )for compoud 1. The anisotropic displacement factor exponent takes the form: -2π 2 [ h 2 a* 2 U 11 +.. + 2 h k a* b* U 12 ] U 11 U 22 U 33 U 23 U 13 U 12 (1) 78(3) 116(3) 57(3) 10(2) 40(2) 32(2) (2) 72(3) 64(2) 43(2) -6(2) 33(2) -4(2) (3) 112(3) 97(3) 51(2) 30(2) 50(3) 30(2) (1) 55(4) 79(3) 38(3) -4(2) 27(3) -3(3) (2) 76(4) 88(3) 48(3) -1(3) 46(4) 0(3) C(1) 52(4) 77(4) 36(4) 3(3) 23(4) 14(4) C(2) 58(5) 141(6) 53(4) -12(4) 22(4) -4(4) C(3) 89(5) 107(5) 74(4) 17(4) 53(4) 30(4) C(4) 60(5) 67(4) 47(4) -6(3) 33(4) 6(4) C(5) 65(5) 71(4) 38(4) 13(3) 28(4) 12(4) C(6) 70(5) 99(5) 42(4) -9(3) 27(4) 3(4) C(7) 203(8) 166(6) 49(4) 14(4) 65(5) -10(5) C(8) 51(5) 315(10) 97(6) -88(6) 15(5) -15(6) C(9) 109(6) 134(6) 92(5) -48(4) 47(4) -15(5) C(10) 92(5) 101(5) 64(4) -6(3) 52(4) -3(4) C(11) 107(6) 110(6) 106(6) 15(5) 72(6) -1(5) C(12) 123(7) 128(6) 128(7) -25(5) 66(6) -36(5) C(13) 177(8) 206(8) 193(8) 34(6) 150(8) -29(6) (4) 105(3) 72(2) 57(3) -16(2) 41(3) -27(2) (5) 69(3) 64(2) 52(2) 3(2) 40(2) 5(2) (6) 91(3) 71(3) 77(3) -4(2) 65(2) -5(2) (3) 85(4) 57(3) 45(3) 2(3) 41(3) 5(3) (4) 84(4) 57(3) 52(3) -10(2) 47(3) -5(3) C(14) 63(4) 50(3) 48(3) -1(3) 38(3) 0(3) C(15) 88(5) 60(4) 66(4) 12(3) 50(4) 15(3) C(16) 90(5) 59(4) 58(4) -15(3) 49(4) -13(3) C(17) 61(4) 60(4) 42(3) -3(3) 29(3) 6(3) C(18) 71(5) 52(4) 61(5) 6(4) 42(4) -1(4) C(19) 100(6) 58(4) 48(4) 10(3) 39(4) 3(4) C(20) 210(30) 290(30) 99(18) 127(16) 130(20) 120(20) C(21) 150(20) 118(14) 82(19) 31(11) -12(16) -17(13) C(22) 190(30) 80(12) 80(11) 14(8) 60(17) 30(18) C(20') 330(90) 280(40) 90(30) 90(30) 130(50) 250(50) C(21') 29(19) 460(80) 110(30) 170(40) -4(18) 70(30) C(22') 190(40) 80(20) 160(20) 81(17) 60(20) 10(20) S37

C(23) 103(5) 64(4) 63(4) -14(3) 55(4) -2(3) C(24) 98(6) 114(6) 75(5) -28(4) 35(5) 24(4) C(25) 118(7) 189(8) 98(6) -27(5) 31(6) 57(6) C(26) 154(7) 139(6) 106(5) -41(4) 51(5) 60(5) S38

Table S8 ydrogen coordinates (x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for compoud 1. x y z U(eq) (2A) 5345-1285 -1992 110 (2B) 5370-2183 -1372 110 (3A) 5595 46-697 106 (3B) 5570 943-1316 106 (7A) 7197-1441 2325 221 (7B) 7187-2748 1879 221 (7C) 6738-1937 1620 221 (8A) 7766-51 2254 261 (8B) 7654 204 1512 261 (8C) 7754-1408 1829 261 (9A) 7073 1146 1908 180 (9B) 6604 621 1231 180 (9C) 6935 1503 1156 180 (10A) 6707-762 -1667 100 (10B) 7087-1767 -1049 100 (11) 7032 1321-912 124 (12A) 7756 1175 127 199 (12B) 7768-548 30 199 (12C) 7445 107 181 199 (13A) 7201 809-1707 252 (13B) 7616-157 -1128 252 (13C) 7617 1569-1023 252 (2) 6745(16) -1660(40) -492(19) 90(19) (1) 6246(15) -970(50) 380(30) 110(20) (15A) 5360 1304 586 83 (15B) 5171 1225 1049 83 (16A) 5916 726 2090 79 (16B) 6106 804 1627 79 (20A) 5796-4779 3510 268 (20B) 5335-4679 2750 268 (20C) 5625-3239 3120 268 (21A) 6528-4515 3699 257 (21B) 6352-2922 3373 257 (21C) 6532-3993 3076 257 (22A) 6137-6682 3053 199 (22B) 6108-6172 2398 199 S39

(22C) 5669-6648 2301 199 (20D) 6082-4797 3686 354 (20E) 5614-4003 3173 354 (20F) 6060-3140 3458 354 (21D) 6386-5088 2660 348 (21E) 6563-4853 3442 348 (21F) 6430-3474 2947 348 (22D) 5582-6451 2136 254 (22E) 5446-6107 2629 254 (22F) 5920-6799 2946 254 (23A) 5729-3304 26 89 (23B) 5264-4069 -289 89 (24) 5610-5809 595 128 (25A) 6221-4583 1487 236 (25B) 6444-4730 1106 236 (25C) 6344-6161 1366 236 (26A) 5499-6352 -459 227 (26B) 5912-7245 170 227 (26C) 5991-5828 -125 227 (3) 5773(14) -1640(40) 2450(19) 84(17) (4) 5384(15) -3240(50) 840(20) 92(19) S40

Table S9 Crystal data and structure refinement for dipeptide 2. Empirical formula C 13 24 2 3 Formula weight 256.34 Empirical formula C 17 31 3 5 Formula weight 357.45 Temperature 298(2) K Wavelength 0.71073 Å Crystal system, space group rthorhombic, P2(1)2(1)2(1) Unit cell dimensions a = 8.869(2) Å alpha = 90 deg. b = 12.673(3) Å beta = 90 deg. c = 18.561(5) Å gamma = 90 deg. Volume 2086.1(10) Å 3 Z, Calculated density 4, 1.138 Mg/m 3 Absorption coefficient 0.084 mm -1 F(000) 776 Crystal size 0.45 x 0.45 x 0.35 mm Theta range for data collection 1.95 to 25.00 deg. Limiting indices -10<=h<=10,-8<=k<=15,-22<=l<=18 Reflections collected / unique 7334 / 3652 [R(int) = 0.0129] Completeness to theta = 25.00 100.0 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9713 and 0.9633 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 3652 / 0 / 245 Goodness-of-fit on F^2 0.995 Final R indices [I>2sigma(I)] R1 = 0.0385, wr2 = 0.1027 R indices (all data) R1 = 0.0501, wr2 = 0.1100 Absolute structure parameter -0.9(12) Extinction coefficient 0.0035(16) Largest diff. peak and hole 0.159 and -0.112 e.å -3 S41

Table S10 Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters (Å 2 x 10 3 ) for dipeptide 2. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. x y z U(eq) (1) 6679(2) 5243(2) 3384(1) 80(1) (2) 7405(2) 4755(1) 1708(1) 63(1) (3) 10301(2) 3573(2) 1276(1) 61(1) (1) 7943(2) 6763(1) 3541(1) 92(1) (2) 6430(1) 5563(1) 1937(1) 73(1) (3) 6139(2) 3556(1) 2374(1) 100(1) (4) 8910(1) 3282(1) 974(1) 60(1) (5) 9974(2) 5232(1) 884(1) 71(1) C(1) 7740(6) 3447(3) 4939(2) 139(1) C(2) 7716(4) 3849(2) 4186(2) 106(1) C(3) 6812(3) 4863(2) 4121(1) 93(1) C(4) 7303(2) 6123(2) 3147(1) 70(1) C(5) 7164(2) 6336(2) 2359(1) 68(1) C(6) 8324(3) 7004(2) 1996(1) 78(1) C(7) 6796(3) 7428(2) 2125(2) 92(1) C(8) 7062(2) 3772(2) 1905(1) 66(1) C(9) 7886(2) 2902(2) 1516(1) 60(1) C(10) 6757(2) 2185(2) 1142(1) 68(1) C(11) 5878(3) 2760(2) 559(2) 95(1) C(12) 7518(3) 1203(2) 852(2) 102(1) C(13) 10780(2) 4559(2) 1147(1) 56(1) C(14) 12367(2) 4783(2) 1402(1) 63(1) C(15) 13180(3) 5467(2) 867(1) 89(1) C(16) 12294(3) 5279(3) 2132(1) 107(1) C(17) 9238(5) 3953(5) 3904(3) 200(2) S42

Table S11 Bond lengths [Å] and angles [deg] for dipeptide 2. (1)-C(4) 1.321(3) (1)-C(3) 1.454(3) (2)-C(8) 1.334(3) (2)-(2) 1.406(2) (3)-C(13) 1.341(3) (3)-(4) 1.405(2) (1)-C(4) 1.231(2) (2)-C(5) 1.413(2) (3)-C(8) 1.225(2) (4)-C(9) 1.439(2) (5)-C(13) 1.215(2) C(1)-C(2) 1.486(4) C(2)-C(17) 1.454(5) C(2)-C(3) 1.519(4) C(4)-C(5) 1.491(3) C(5)-C(7) 1.487(4) C(5)-C(6) 1.494(3) C(6)-C(7) 1.477(4) C(8)-C(9) 1.507(3) C(9)-C(10) 1.520(3) C(10)-C(12) 1.515(3) C(10)-C(11) 1.519(4) C(13)-C(14) 1.512(3) C(14)-C(16) 1.495(3) C(14)-C(15) 1.503(3) C(4)-(1)-C(3) 124.0(2) C(8)-(2)-(2) 117.25(17) C(13)-(3)-(4) 116.81(17) (2)-(2)-C(5) 112.86(13) (3)-(4)-C(9) 111.24(13) C(17)-C(2)-C(1) 110.8(4) C(17)-C(2)-C(3) 112.6(3) C(1)-C(2)-C(3) 111.9(2) (1)-C(3)-C(2) 113.4(2) (1)-C(4)-(1) 123.5(2) (1)-C(4)-C(5) 120.1(2) (1)-C(4)-C(5) 116.41(19) S43

(2)-C(5)-C(7) 112.41(19) (2)-C(5)-C(4) 117.18(19) C(7)-C(5)-C(4) 118.21(19) (2)-C(5)-C(6) 117.39(19) C(7)-C(5)-C(6) 59.43(17) C(4)-C(5)-C(6) 119.20(19) C(7)-C(6)-C(5) 60.06(18) C(6)-C(7)-C(5) 60.51(16) (3)-C(8)-(2) 123.7(2) (3)-C(8)-C(9) 120.08(19) (2)-C(8)-C(9) 116.20(17) (4)-C(9)-C(8) 113.35(16) (4)-C(9)-C(10) 107.19(15) C(8)-C(9)-C(10) 109.69(17) C(12)-C(10)-C(11) 111.7(2) C(12)-C(10)-C(9) 111.12(19) C(11)-C(10)-C(9) 112.12(19) (5)-C(13)-(3) 122.65(18) (5)-C(13)-C(14) 122.76(18) (3)-C(13)-C(14) 114.45(18) C(16)-C(14)-C(15) 112.2(2) C(16)-C(14)-C(13) 108.84(19) C(15)-C(14)-C(13) 110.34(18) Symmetry transformations used to generate equivalent atoms: S44

Table S12 Anisotropic displacement parameters (Å 2 x 10 3 ) for dipeptide 2. The anisotropic displacement factor exponent takes the form: -2π 2 [ h 2 a* 2 U 11 +.. + 2 h k a* b* U 12 ] U11 U22 U33 U23 U13 U12 (1) 89(1) 72(1) 80(1) -22(1) 17(1) -20(1) (2) 56(1) 69(1) 65(1) -15(1) 10(1) -2(1) (3) 47(1) 59(1) 77(1) -2(1) -5(1) 4(1) (1) 116(1) 75(1) 85(1) -21(1) -9(1) -24(1) (2) 48(1) 81(1) 90(1) -29(1) -4(1) 5(1) (3) 105(1) 97(1) 97(1) -40(1) 46(1) -50(1) (4) 53(1) 69(1) 58(1) -6(1) 0(1) -7(1) (5) 56(1) 68(1) 89(1) 15(1) 0(1) 4(1) C(1) 189(4) 130(3) 99(2) -6(2) 15(3) 28(3) C(2) 120(2) 110(2) 88(2) -20(2) 9(2) 15(2) C(3) 112(2) 87(2) 81(2) -20(1) 28(1) -5(2) C(4) 66(1) 64(1) 79(1) -19(1) 7(1) -4(1) C(5) 53(1) 68(1) 82(1) -21(1) 1(1) 3(1) C(6) 82(1) 71(1) 82(1) -9(1) 3(1) -5(1) C(7) 96(2) 78(2) 103(2) -14(1) -7(2) 24(1) C(8) 61(1) 75(1) 62(1) -17(1) 8(1) -23(1) C(9) 60(1) 65(1) 56(1) 1(1) 0(1) -5(1) C(10) 72(1) 64(1) 68(1) -12(1) 8(1) -17(1) C(11) 84(2) 107(2) 93(2) -17(2) -25(1) -17(2) C(12) 123(2) 72(2) 111(2) -28(1) 22(2) -14(2) C(13) 51(1) 58(1) 59(1) 0(1) 5(1) 4(1) C(14) 50(1) 66(1) 72(1) -2(1) 1(1) 0(1) C(15) 67(1) 102(2) 97(2) 7(1) -3(1) -20(1) C(16) 82(2) 149(3) 89(2) -35(2) -8(2) -5(2) C(17) 135(3) 303(7) 161(4) 29(4) 58(3) 82(4) S45

Table S13 ydrogen coordinates (Å x 10 4 ) and isotropic displacement parameters (2 x 10 3 ) for dipeptide 2. x y z U(eq) (1A) 8269 2787 4954 209 (1B) 6724 3347 5104 209 (1C) 8241 3948 5243 209 (2A) 7202 3317 3893 127 (3C) 5809 4745 4314 112 (3D) 7290 5405 4411 112 (6A) 9143 7278 2288 94 (6B) 8598 6827 1504 94 (7A) 6136 7511 1712 111 (7B) 6680 7961 2495 111 (9) 8455 2486 1869 72 (10) 6029 1956 1507 82 (11A) 6555 2975 183 142 (11B) 5401 3371 763 142 (11C) 5124 2298 364 142 (12A) 6770 734 659 153 (12B) 8052 855 1235 153 (12C) 8215 1396 479 153 (14) 12908 4112 1442 75 (15A) 13244 5106 413 133 (15B) 14177 5616 1040 133 (15C) 12637 6117 805 133 (16A) 11931 5990 2089 160 (16B) 13282 5284 2343 160 (16C) 11621 4881 2433 160 (17A) 9815 4406 4214 300 (17B) 9200 4251 3429 300 (17C) 9705 3270 3884 300 (3) 10910(20) 3055(17) 1357(10) 56(6) (1) 6240(20) 4827(18) 3044(12) 67(6) (2) 7990(19) 4929(13) 1338(9) 39(4) Symmetry transformations used to generate equivalent atoms: #1 -x+2,y-1/2,-z+1/2 S46

Table S14 Crystal data and structure refinement for tripeptide 8. Empirical formula C 22 40 4 7 Formula weight 472.58 Temperature 295(2) K Wavelength 0.71073 Å Crystal system, space group Tetragonal, P 4(1) 2(1) 2 Unit cell dimensions a = 9.2000(19) Å alpha = 90.00(3) deg. b = 9.200(3) Å beta = 90.00(3) deg. c = 64.15(2) Å gamma = 90.00(2) deg. Volume 5430(3) Å 3 Z, Calculated density 8, 1.156 Mg/m 3 Absorption coefficient 0.086 mm^-1 F(000) 2048 Crystal size 0.20 x 0.20 x 0.15 mm Theta range for data collection 1.27 to 25.19 deg. Index ranges 0<=h<=11, 0<=k<=11, -1<=l<=76 Reflections collected / unique 5646 / 4881 [R(int) = 0.2101] Completeness to 2theta = 25.19 100.0% Absorption correction one Max. and min. transmission 0.9872 and 0.9830 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 4881 / 4 / 320 Goodness-of-fit on F^2 0.960 Final R indices [I>2sigma(I)] R1 = 0.0856, wr2 = 0.2856 R indices (all data) R1 = 0.4539, wr2 = 0.4376 Absolute structure parameter -10(8) Extinction coefficient 0.0004(3) Largest diff. peak and hole 0.307 and -0.335 e. Å -3 S47

Table S15 Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters (Å 2 x 10 3 ) for tripeptide 8. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. x y z U(eq) C(1) 9010(8) 12332(7) 132(1) 87(3) C(2) 8154(9) 11329(9) 4(1) 117(4) C(3) 8817(9) 13894(7) 61(1) 121(4) C(4) 8612(7) 12249(7) 367(1) 84(3) (1) 8829(5) 10767(5) 450(1) 68(2) C(5) 7784(8) 10080(7) 535(1) 68(2) (1) 6503(5) 10415(5) 565(1) 86(2) C(6) 8140(6) 8515(7) 603(1) 60(2) C(7) 7117(7) 7346(7) 516(1) 62(2) C(8) 7064(7) 7375(7) 281(1) 72(2) C(9) 7497(7) 5869(6) 594(1) 74(3) (2) 9616(4) 8134(4) 545(1) 61(1) (2) 10469(6) 7747(5) 710(1) 69(2) C(10) 11649(7) 8638(6) 766(1) 60(2) (3) 11689(4) 9875(4) 691(1) 83(2) C(11) 12519(6) 8050(6) 931(1) 58(2) C(12) 13031(9) 9070(7) 1100(1) 101(3) C(13) 14076(6) 8686(8) 940(1) 83(3) (4) 12338(4) 6592(4) 992(1) 58(1) (3) 13044(5) 5615(5) 856(1) 59(2) C(14) 12253(6) 4586(6) 759(1) 55(2) (5) 10922(4) 4741(4) 745(1) 64(2) C(15) 13080(5) 3419(6) 649(1) 57(2) C(16) 12720(8) 3426(8) 410(1) 84(3) C(17) 13152(10) 4820(8) 303(1) 123(4) C(18) 13417(10) 2035(7) 317(1) 97(3) (6) 14618(4) 3672(4) 667(1) 47(1) (4) 15296(5) 2680(5) 801(1) 67(2) C(19) 15869(7) 3181(8) 974(1) 71(2) (7) 15603(4) 4408(5) 1043(1) 71(2) C(20) 16883(6) 2145(7) 1087(1) 70(2) C(21) 16572(10) 2134(11) 1310(1) 150(4) C(22) 18448(7) 2546(9) 1037(1) 113(4) S48

Table S16 Bond lengths [Å] and angles [deg] for tripeptide 8. C(1)-C(2) 1.463(10) C(1)-C(3) 1.517(9) C(1)-C(4) 1.556(10) C(1)-(1) 0.9800 C(2)-(2A) 0.9599 C(2)-(2B) 0.9599 C(2)-(2C) 0.9599 C(3)-(3A) 0.9599 C(3)-(3B) 0.9599 C(3)-(3C) 0.9599 C(4)-(1) 1.476(8) C(4)-(4A) 0.9700 C(4)-(4B) 0.9700 (1)-C(5) 1.272(8) (1)-(1X) 0.864(14) C(5)-(1) 1.234(8) C(5)-C(6) 1.540(9) C(6)-(2) 1.450(7) C(6)-C(7) 1.534(9) C(6)-(6) 0.9800 C(7)-C(9) 1.491(8) C(7)-C(8) 1.507(9) C(7)-(7) 0.9800 C(8)-(8A) 0.9599 C(8)-(8B) 0.9599 C(8)-(8C) 0.9599 C(9)-(9A) 0.9599 C(9)-(9B) 0.9599 C(9)-(9C) 0.9599 (2)-(2) 1.366(6) (2)-C(10) 1.407(8) (2)-(2X) 0.862(12) C(10)-(3) 1.238(7) C(10)-C(11) 1.433(9) C(11)-(4) 1.406(7) C(11)-C(12) 1.506(10) C(11)-C(13) 1.549(8) C(12)-C(13) 1.449(10) S49

C(12)-(12A) 0.9700 C(12)-(12B) 0.9700 C(13)-(13A) 0.9700 C(13)-(13B) 0.9700 (4)-(3) 1.411(6) (3)-C(14) 1.345(7) (3)-(3X) 0.864(11) C(14)-(5) 1.236(6) C(14)-C(15) 1.496(8) C(15)-(6) 1.439(6) C(15)-C(16) 1.564(9) C(15)-(15) 0.9800 C(16)-C(17) 1.507(10) C(16)-C(18) 1.551(10) C(16)-(16) 0.9800 C(17)-(17A) 0.9599 C(17)-(17B) 0.9599 C(17)-(17C) 0.9599 C(18)-(18A) 0.9599 C(18)-(18B) 0.9599 C(18)-(18C) 0.9599 (6)-(4) 1.400(6) (4)-C(19) 1.311(8) (4)-(4X) 0.864(13) C(19)-(7) 1.238(8) C(19)-C(20) 1.519(9) C(20)-C(21) 1.458(10) C(20)-C(22) 1.521(9) C(20)-(20) 0.9800 C(21)-(21A) 0.9599 C(21)-(21B) 0.9599 C(21)-(21C) 0.9599 C(22)-(22A) 0.9599 C(22)-(22B) 0.9599 C(22)-(22C) 0.9599 C(2)-C(1)-C(3) 111.6(6) C(2)-C(1)-C(4) 112.7(6) C(3)-C(1)-C(4) 107.9(6) C(2)-C(1)-(1) 108.2 C(3)-C(1)-(1) 108.2 S50

C(4)-C(1)-(1) 108.2 C(1)-C(2)-(2A) 109.5 C(1)-C(2)-(2B) 109.5 (2A)-C(2)-(2B) 109.5 C(1)-C(2)-(2C) 109.5 (2A)-C(2)-(2C) 109.5 (2B)-C(2)-(2C) 109.5 C(1)-C(3)-(3A) 109.5 C(1)-C(3)-(3B) 109.5 (3A)-C(3)-(3B) 109.5 C(1)-C(3)-(3C) 109.5 (3A)-C(3)-(3C) 109.5 (3B)-C(3)-(3C) 109.5 (1)-C(4)-C(1) 111.3(5) (1)-C(4)-(4A) 109.4 C(1)-C(4)-(4A) 109.4 (1)-C(4)-(4B) 109.4 C(1)-C(4)-(4B) 109.4 (4A)-C(4)-(4B) 108.0 C(5)-(1)-C(4) 120.7(5) C(5)-(1)-(1X) 130.6(19) C(4)-(1)-(1X) 105(2) (1)-C(5)-(1) 131.7(6) (1)-C(5)-C(6) 113.1(5) (1)-C(5)-C(6) 115.2(6) (2)-C(6)-C(7) 108.2(5) (2)-C(6)-C(5) 110.7(5) C(7)-C(6)-C(5) 115.0(5) (2)-C(6)-(6) 107.6 C(7)-C(6)-(6) 107.6 C(5)-C(6)-(6) 107.6 C(9)-C(7)-C(8) 111.2(5) C(9)-C(7)-C(6) 111.9(5) C(8)-C(7)-C(6) 111.7(5) C(9)-C(7)-(7) 107.3 C(8)-C(7)-(7) 107.3 C(6)-C(7)-(7) 107.3 C(7)-C(8)-(8A) 109.5 C(7)-C(8)-(8B) 109.5 (8A)-C(8)-(8B) 109.5 C(7)-C(8)-(8C) 109.5 S51

(8A)-C(8)-(8C) 109.5 (8B)-C(8)-(8C) 109.5 C(7)-C(9)-(9A) 109.5 C(7)-C(9)-(9B) 109.5 (9A)-C(9)-(9B) 109.5 C(7)-C(9)-(9C) 109.5 (9A)-C(9)-(9C) 109.5 (9B)-C(9)-(9C) 109.5 (2)-(2)-C(6) 113.8(4) (2)-(2)-C(10) 119.3(5) (2)-(2)-(2X) 114(3) C(10)-(2)-(2X) 120(3) (3)-C(10)-(2) 117.3(5) (3)-C(10)-C(11) 128.3(6) (2)-C(10)-C(11) 113.5(5) (4)-C(11)-C(10) 119.9(5) (4)-C(11)-C(12) 115.7(5) C(10)-C(11)-C(12) 118.0(5) (4)-C(11)-C(13) 117.4(5) C(10)-C(11)-C(13) 113.6(5) C(12)-C(11)-C(13) 56.6(5) C(13)-C(12)-C(11) 63.2(5) C(13)-C(12)-(12A) 117.4 C(11)-C(12)-(12A) 117.4 C(13)-C(12)-(12B) 117.4 C(11)-C(12)-(12B) 117.4 (12A)-C(12)-(12B) 114.5 C(12)-C(13)-C(11) 60.2(4) C(12)-C(13)-(13A) 117.7 C(11)-C(13)-(13A) 117.7 C(12)-C(13)-(13B) 117.7 C(11)-C(13)-(13B) 117.7 (13A)-C(13)-(13B) 114.9 C(11)-(4)-(3) 112.5(4) C(14)-(3)-(4) 119.0(4) C(14)-(3)-(3X) 123(4) (4)-(3)-(3X) 118(4) (5)-C(14)-(3) 119.3(5) (5)-C(14)-C(15) 123.4(5) (3)-C(14)-C(15) 116.7(5) (6)-C(15)-C(14) 110.2(5) S52

(6)-C(15)-C(16) 106.7(5) C(14)-C(15)-C(16) 110.7(5) (6)-C(15)-(15) 109.7 C(14)-C(15)-(15) 109.7 C(16)-C(15)-(15) 109.7 C(17)-C(16)-C(18) 114.7(6) C(17)-C(16)-C(15) 113.1(6) C(18)-C(16)-C(15) 106.6(6) C(17)-C(16)-(16) 107.4 C(18)-C(16)-(16) 107.4 C(15)-C(16)-(16) 107.4 C(16)-C(17)-(17A) 109.5 C(16)-C(17)-(17B) 109.5 (17A)-C(17)-(17B) 109.5 C(16)-C(17)-(17C) 109.5 (17A)-C(17)-(17C) 109.5 (17B)-C(17)-(17C) 109.5 C(16)-C(18)-(18A) 109.5 C(16)-C(18)-(18B) 109.5 (18A)-C(18)-(18B) 109.5 C(16)-C(18)-(18C) 109.5 (18A)-C(18)-(18C) 109.5 (18B)-C(18)-(18C) 109.5 (4)-(6)-C(15) 112.5(4) C(19)-(4)-(6) 118.0(5) C(19)-(4)-(4X) 132(2) (6)-(4)-(4X) 108.5(19) (7)-C(19)-(4) 123.0(6) (7)-C(19)-C(20) 121.4(6) (4)-C(19)-C(20) 115.6(6) C(21)-C(20)-C(19) 110.7(6) C(21)-C(20)-C(22) 113.3(6) C(19)-C(20)-C(22) 109.1(6) C(21)-C(20)-(20) 107.8 C(19)-C(20)-(20) 107.8 C(22)-C(20)-(20) 107.8 C(20)-C(21)-(21A) 109.5 C(20)-C(21)-(21B) 109.5 (21A)-C(21)-(21B) 109.5 C(20)-C(21)-(21C) 109.5 (21A)-C(21)-(21C) 109.5 S53

(21B)-C(21)-(21C) 109.5 C(20)-C(22)-(22A) 109.5 C(20)-C(22)-(22B) 109.5 (22A)-C(22)-(22B) 109.5 C(20)-C(22)-(22C) 109.5 (22A)-C(22)-(22C) 109.5 (22B)-C(22)-(22C) 109.5 Symmetry transformations used to generate equivalent atoms: S54

Table S17 Anisotropic displacement parameters (Å 2 x 10 3 ) for tripeptide 8. The anisotropic displacement factor exponent takes the form: -2π 2 [ h 2 a* 2 U 11 +.. + 2 h k a* b* U 12 ] U11 U22 U33 U23 U13 U12 C(1) 97(5) 66(5) 99(6) 3(5) 5(5) 25(4) C(2) 90(6) 130(7) 131(7) -20(6) -27(6) 5(5) C(3) 145(7) 72(5) 146(8) 42(5) 30(7) 46(5) C(4) 55(4) 101(6) 96(6) -3(5) 10(4) -28(4) (1) 74(3) 38(3) 92(4) 18(3) 29(3) -8(3) C(5) 106(5) 59(4) 37(4) -5(3) -12(4) 30(4) (1) 74(3) 74(3) 110(4) 9(3) 19(3) 34(3) C(6) 19(3) 119(5) 42(4) -35(4) 12(3) -7(3) C(7) 42(3) 76(4) 68(4) -11(4) 17(4) -2(3) C(8) 64(4) 65(4) 87(5) 16(4) -17(4) 0(4) C(9) 74(4) 44(4) 105(6) 18(4) 2(4) -12(4) (2) 68(3) 65(3) 49(2) 2(2) -11(2) -3(2) (2) 76(3) 58(3) 72(4) -1(3) -27(3) -8(3) C(10) 53(4) 55(4) 71(5) -14(4) 13(4) 10(3) (3) 68(3) 30(2) 149(4) 19(3) -29(3) -8(2) C(11) 53(4) 52(4) 67(4) 8(4) -7(4) 16(3) C(12) 133(6) 60(4) 110(6) -30(5) -37(6) 29(4) C(13) 32(3) 95(5) 123(6) -4(5) 23(4) 17(4) (4) 57(2) 56(3) 60(3) 13(2) 6(2) 2(2) (3) 56(3) 32(3) 88(4) 14(3) 18(3) 13(2) C(14) 52(3) 25(3) 87(5) 18(3) -17(4) -15(3) (5) 24(2) 37(2) 132(4) 6(3) -3(3) -1(2) C(15) 11(3) 50(4) 110(5) 11(4) 2(4) 10(3) C(16) 84(5) 108(6) 60(4) -16(5) -26(4) 5(5) C(17) 158(8) 97(6) 115(6) 57(5) -35(6) 12(6) C(18) 157(7) 56(4) 77(5) -12(4) -18(6) -8(5) (6) 60(2) 30(2) 52(2) 11(2) -12(2) 6(2) (4) 50(3) 80(4) 70(4) -22(3) -12(3) 30(3) C(19) 75(5) 82(5) 58(4) -10(4) 7(4) 7(4) (7) 58(2) 83(3) 72(3) -11(3) -21(2) 6(2) C(20) 38(3) 93(5) 80(5) 19(4) -22(4) 43(3) S55

C(21) 158(8) 226(10) 65(6) 32(7) 4(6) 96(7) C(22) 52(4) 127(7) 162(8) 9(6) -19(5) 29(5) S56

Table S18 ydrogen coordinates ( x 10 4 ) and isotropic displacement parameters (Å 2 x 10 3 ) for tripeptide 8. x y z U(eq) (1) 10038 12075 116 105 (2A) 8402 10346 39 176 (2B) 8359 11498-141 176 (2C) 7138 11486 30 176 (3A) 8966 13956-87 182 (3B) 9512 14500 131 182 (3C) 7852 14215 95 182 (4A) 9214 12925 444 100 (4B) 7605 12531 386 100 (1X) 9614(13) 10450(3) 391(4) 81 (6) 8077 8480 755 72 (7) 6137 7571 566 75 (8A) 8035 7334 227 108 (8B) 6603 8256 236 108 (8C) 6520 6554 232 108 (9A) 6674 5236 579 111 (9B) 7763 5929 739 111 (9C) 8299 5490 516 111 (2X) 10520(6) 6822(10) 731(7) 83 (12A) 12649 10052 1098 121 (12B) 13179 8667 1238 121 (13A) 14862 8036 978 100 (13B) 14332 9425 838 100 (3X) 13980(10) 5660(6) 847(8) 90(2) (15) 12836 2469 708 68 (16) 11664 3328 396 101 (17A) 14191 4859 291 185 (17B) 12820 5633 384 185 (17C) 12720 4854 167 185 (18A) 12966 1815 186 145 (18B) 13278 1237 411 145 (18C) 14438 2193 296 145 (4X) 15410(5) 1868(12) 735(3) 80 S57

(20) 16705 1164 1033 85 (21A) 16593 3112 1362 225 (21B) 17291 1563 1381 225 (21C) 15628 1722 1333 225 (22A) 18723 3390 1115 170 (22B) 18534 2751 890 170 (22C) 19076 1750 1072 170 S58

Table S19 Torsion angles [deg] for tripeptide 8. C(2)-C(1)-C(4)-(1) 58.6(8) C(3)-C(1)-C(4)-(1) -177.7(6) C(1)-C(4)-(1)-C(5) -122.6(6) C(4)-(1)-C(5)-(1) 0.3(11) C(4)-(1)-C(5)-C(6) 176.7(5) (1)-C(5)-C(6)-(2) 174.5(5) (1)-C(5)-C(6)-(2) -2.6(7) (1)-C(5)-C(6)-C(7) 51.6(7) (1)-C(5)-C(6)-C(7) -125.5(6) (2)-C(6)-C(7)-C(9) 57.7(7) C(5)-C(6)-C(7)-C(9) -178.0(5) (2)-C(6)-C(7)-C(8) -67.6(6) C(5)-C(6)-C(7)-C(8) 56.6(7) C(7)-C(6)-(2)-(2) -111.9(5) C(5)-C(6)-(2)-(2) 121.3(5) C(6)-(2)-(2)-C(10) -113.6(6) (2)-(2)-C(10)-(3) 14.2(8) (2)-(2)-C(10)-C(11) -175.4(5) (3)-C(10)-C(11)-(4) -178.2(6) (2)-C(10)-C(11)-(4) 12.7(8) (3)-C(10)-C(11)-C(12) 31.3(10) (2)-C(10)-C(11)-C(12) -137.8(6) (3)-C(10)-C(11)-C(13) -32.1(9) (2)-C(10)-C(11)-C(13) 158.8(5) (4)-C(11)-C(12)-C(13) 107.2(6) C(10)-C(11)-C(12)-C(13) -101.1(7) (4)-C(11)-C(13)-C(12) -104.0(6) C(10)-C(11)-C(13)-C(12) 109.0(6) C(10)-C(11)-(4)-(3) 79.3(6) C(12)-C(11)-(4)-(3) -129.6(5) C(13)-C(11)-(4)-(3) -65.6(7) C(11)-(4)-(3)-C(14) -121.5(5) (4)-(3)-C(14)-(5) 19.4(8) (4)-(3)-C(14)-C(15) -169.2(5) (5)-C(14)-C(15)-(6) 170.0(5) (3)-C(14)-C(15)-(6) -1.0(8) (5)-C(14)-C(15)-C(16) 52.2(8) (3)-C(14)-C(15)-C(16) -118.9(6) S59

(6)-C(15)-C(16)-C(17) -57.6(7) C(14)-C(15)-C(16)-C(17) 62.4(7) (6)-C(15)-C(16)-C(18) 69.4(6) C(14)-C(15)-C(16)-C(18) -170.7(5) C(14)-C(15)-(6)-(4) 108.2(5) C(16)-C(15)-(6)-(4) -131.6(5) C(15)-(6)-(4)-C(19) -114.8(6) (6)-(4)-C(19)-(7) 14.4(9) (6)-(4)-C(19)-C(20) -166.3(5) (7)-C(19)-C(20)-C(21) 44.5(9) (4)-C(19)-C(20)-C(21) -134.8(7) (7)-C(19)-C(20)-C(22) -80.9(8) (4)-C(19)-C(20)-C(22) 99.8(7) Symmetry transformations used to generate equivalent atoms: #1 x-1,y,z #2 -x+5/2,y+1/2,-z+1/4 #3 x+1,y,z #4 x,y-1,z #5 x+1,y-1,z #6 -x+5/2,y-1/2,-z+1/4 S60

VII. MR spectra of compounds 1 22. S61

S62

S63

S64

S65

S66

S67

S68

S69

S70

S71

S72

S73

S74

S75

S76

S77

S78

S79