A Mild Ligand-free Iron-catalyzed Liberation of Alcohols from Allylcarbonates

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1 A Mild Ligand-free Iron-catalyzed Liberation of Alcohols from Allylcarbonates André P. Dieskau, and Bernd Plietker*. Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D Stuttgart Germany. S-I General remarks S-2 S-II General procedure for the preparation of Alloc protected alcohols S-2 S-III Spectroscopic data of Alloc protected alcohols S-2 S-IV General procedure for the Iron-catalyzed deprotection S-9 S-V Spectroscopic data of deprotected alcohols S-10 S-VI Glycosylation reactions S-17 S-VII 1 H- and 13 C-NMR-spectra S-22 S-1

2 S-I General Remarks All the reactions and manipulations which are sensitive to air or moisture were performed under dry nitrogen by using standard Schlenk techniques. All solvents were purified prior to use. NMR spectra were recorded on a Bruker AV 300 spectrometer at 300 MHz ( 1 H NMR), 75MHz ( 13 C NMR) or a Bruker AV 500 spectrometer at 500 MHz ( 1 H NMR), MHz ( 13 C NMR). Chemical shifts are reported in ppm down field using tetramethylsilane as an internal standard. IR spectra were measured on a Bruker Vector 22 FT-IR spectrometer in an ATR mode. Mass spectra were measured using electrospray ionization on a Bruker Micro-TOF-Q. The iron catalyst [Bu 4 N][Fe(CO) 3 (NO)] was prepared as described earlier. 1 S-II General procedure A (GP-A) for the preparation of Alloc protected alcohols To a solution of the alcohol (20 mmol, 1 eq.) in dry THF was added pyridine (2.26 ml, 28 mmol, 1.4 eq.) in one portion. The reaction mixture was cooled to 0 C followed by the dropwise addition of allyl chloroformiate (2.56 ml, 24 mmol, 1.2 eq.). The white suspension was stirred at room temperature over night, before it was quenched by the addition of water. The mixture was extracted with ethyl acetate (3x). The combined organic layers were successively washed with 2 N HCl (2 x 10 ml, 2N), sat. aqueous NaHCO 3 (10 ml) and brine (10 ml). After drying over Na 2 SO 4 and removal of the solvent under reduced pressure, the carbonate was purified by means of flash chromatography on silica gel using hexanes and ethyl acetate as the eluent. S-III Spectroscopic data of Alloc protected alcohols : Menthylallylcarbonat (1) [2] The carbonate was obtained according to GP-A as a colorless oil (4.47 g, 18.6 mmol, 93%). R f 0.86 (petroleum ether/diethyl ether, 20:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), 5.35 (ddt, J = 17.1, 1.8, 0.9 Hz, 1H), 5.26 (ddt, J = 10.4, 1.8, 0.9 Hz, 1H), 4.62 (app. dq, J = 5.9, 1.1 Hz, 2H), 4.52 (td, J = 10.9, 4.3 Hz, 2H), (m, 1H), 1.97 (app. quint.d, J = 7.0, 2.7 Hz, 1H), (m, 2H), (m, 2H), 0.92 (d, J = 6.4 Hz, 3H), 0.90 (d, J = 7.2 Hz, 3H), 0.79 (d, J = 6.7 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 154.7, 131.8, 118.6, 78.5, 68.1, 47.0, 40.8, 34.1, 31.4, 26.1, 23.4, 22.0, 20.7, 16.3 ppm; IR (film) ν 2955 (w), 1738 (s), 1455 (w), 1370 (w), 1248 (vs), 958 (m), 790 (m) cm -1 ; MS (EI, 70 ev): m/z = 138 (100); 123 (24); 95 (44); 83 (25); 81 (29); 69 (12); 55 (12); 41 (30) %; MS (CI, positive ion, reactand gas = CH 4 ): m/z (%) = 241 (14); 139 (100); 138 (36); 123 (12); 95 (23); 81 (22); 69 (6); 55 (7); 43 (5). 1 Holzwarth, M.; Dieskau, A.; Tabassam, M.; Plietker, B.; Angew. Chem. 2009, 121, 7387; Angew. Chem. Int. Ed. 2009, 48, Genet, J-P.; Blart, E; Savignac, M.; Lemeune, S.; Lemaire-Audoire, S.; Tetrahedron 1994, 50, 497. S-2

3 Dodecylallylcarbonat (5) The carbonate was obtained according to GP-A as a colorless oil (4.98 g, 18.4 mmol, 92%). R f 0.85 (petroleum ether/ethyl acetate, 5:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), (m, 2H), 4.62 (dt, J = 5.8 Hz, J = 1.5 Hz, 2H), 4.14 (t, J = 6.8 Hz, 2H), (m, 2H), (m, 18H), 0.88 (t, J = 6.9 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.2, 131.8, 118.8, 68.3, 68.3, 32.0, 29.7, 29.6, 29.6, 29.5, 29.4, 29.3, 28.7, 25.7, 22.7, 14.1 ppm; IR (film) ν 2923 (m), 2854 (m), 1745 (s), 1464 (w), 1395 (w), 1245 (vs), 960 (m), 931 (m), 791 (w) cm -1 ; MS (EI, 70 ev) m/z (%) 270 (1), 168 (24), 140 (10), 111 (18), 103 (100), 83 (31), 69 (31), 57 (40), 41 (52). Allyl 2-phenylethyl carbonate (6) [3] OAlloc The carbonate was obtained according to GP-A as a colorless oil (4.04 g, 19.6 mmol, 98%). R f 0.55 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 5H), (m, 1H), (m, 2H), 4.61 (dt, J = 5.8, 1.2 Hz, 2H), 4.35 (t, J = 7.3 Hz, 2H), 2.99 (t, J = 7.3 Hz, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.0, 137.2, 131.6, 129.0, 128.6, 126.7, 118.9, 68.5, 68.4, 35.2 ppm; IR (film) ν 1740 (s), 1454 (w), 1393 (m), 1241 (vs), 962 (m), 790 (m), 749 (m), 698 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 128 (1), 105 (40), 104 (100), 91 (18), 77 (8), 65 (6), 41 (13). Allyl diphenylmethylcarbonate (7) [4] The carbonate was obtained according to GP-A as a colorless oil (4.78 g, 17.8 mmol, 89%). R f 0.76 (petroleum ether/diethyl ether, 4:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 10H), 6.71 (s, 1H), (m, 1H), (m,2h), 4.63 (dt, J = 5.7, 1.3 Hz, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 153.4, 138.6, 130.5, 127.5, 127.1, 126.0, 118.0, 79.8, 76.3, 76.0, 75.4, 67.7 ppm; IR (film) ν 1742 (s), 1454 (w), 1368 (w), 1238 (vs), 1184 (m), 952 (m), 909 (m), 744 (m), 695 (s), 602 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 268 (17); 227 (18); 183 (33); 166 (100); 165 (56); 152 (9); 105 (24); 77 (8). 3 Tanaka, S.; Saburi, H.; Murase, T.; Yoshimura, M.; Kitamura, M.; J.Org. Chem. 2006, 71, Cookson,R.C.; Wallis, S.R.; J. Chem. Soc. Sect. B 1966, S-3

4 Allyl 2-phenylethyl carbonate (15) [5] The carbonate was obtained according to GP-A as a colorless oil (3.13 g, 17.6 mmol, 88%). R f 0.54 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): (m, 2H), (m, 1H), (m, 2H), (m, 1H), (m, 1H), (m, 1H), (m, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 153.7, 151.3, 131.3, 129.7, 126.3, 121.2, 119.7, 69.3 ppm; IR (film) 1757 (s), 1593 (w), 1494 (w), 1233 (s), 1203 (s), 1053 (m), 945 (m), 831 (w), 771 (m), 687 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 178 (14), 134 (61), 119 (16), 94 (27), 77 (25), 65 (10), 51 (5), 41 (100). 4-Allyloxycarbonyloxy-benzoic acid methyl ester (16) The carbonate was obtained according to GP-A as a white solid (4.20 g, 17.8 mmol, 89%); mp. 56 C; R f 0.82 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 2H), (m, 1H), 5.44 (dd, J = 17.0, 1.4 Hz, 1H), 5.35 (dd, J = 10.7, 1.2 Hz, 1H), 4.75 (t, J = 5.7, 1.3 Hz, 2H), 3.91 (s,3h) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 166.2, 154.5, 152.8, 131.3, 130.9, 127.9, 121.0, 119.8, 69.4, 52.2 ppm; IR (film) ν 2954 (w), 1754 (s), 1716 (s), 1605 (m), 1440 (m), 1266 (s), 1161 (m), 1114 (s), 945 (s), 843 (m), 774 (m), 732 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 236 (5), 205 (8), 192 (41), 177 (5), 161 (23), 133 (22), 121 (19), 105 (10), 92 (8), 41 (100); HRMS (ESI, C 12 H 12 O 5 + Na + ) calcd.: ; found: Allyl 2-phenylethyl carbonate (8) [6] The carbonate was obtained according to GP-A as a colorless oil (3.54 g, 16.2 mmol, 81%). R f 0.37 (petroleum ether/diethyl ether, 15:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 5H), 6.70 (d, J = 16.0 Hz, 1H), 6.30 (dt, J = 16.0, 6.5 Hz, 1H), (m, 1H), (m, 2H), 4.80 (d, J = 6.5, 1.2 Hz, 2H), 4.65 (dt, J = 5.7, 1.5 Hz, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 154.9, 136.1, 134.9, 131.6, 128.6, 128.2, 126.7, 122.4, 119.0, 68.5, 68.4, 30.9 ppm; IR (film) ν 1740 (s), 1448 (w), 1387 (w), 1235 (vs), 950 (s), 789 (m), 745 (m), 691 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 218 (46), 177 (24), 133 (56), 117 (100), 115 (63), 105 (19), 91 (23), 77 (8), 55 (8), 41 (18). 1,2-Isopropyliden-3-O-allyloxycarbonyl-sn-glycerin (9) The carbonate was obtained according to GP-A as a colorless oil (3.59 g, 16.6 mmol, 83%). R f 0.59 (petroleum ether/diethyl ether, 15:1); 1 H NMR (300 MHz, 5 Kamijo, S.; Yamamoto, Y.; J. Org. Chem. 2003, 68, Schving, S.; Bull. Soc. Chim. France 1928; 43, 858. S-4

5 CDCl 3 ): δ (m, 1H), 5.37 (m, 1H), 5.28 (m, 1H), 4.64 (dt, J = 5.8 Hz, 1.3 Hz, 2H), 4.35 (app. quintett, J = 5.8 Hz, 1H), 4.18 (d, J = 5.7 Hz, 2H), 4.09 (dd, J = 8.7 Hz, 6.6 Hz, 1H), 3.79 (dd, J = 8.5 Hz, 5.9 Hz, 1H), 1.44 (s, 3H), 1.37 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.0, 131.6, 119.3, 110.1, 73.5, 68.9, 68.1, 66.5, 26.9, 25.5 ppm; IR (film) ν 2987 (w), 1745 (s), 1371 (m), 1239 (vs), 1082 (m), 1054 (m), 965 (m), 839 (m), 788 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 201 (95), 158 (14), 115 (16), 101 (48), 84 (4), 72 (15), 57 (20), 43 (52), 41 (100); HRMS (ESI, C 10 H 16 O 5 + Na + ) calcd.: ; found: Allyl 4-(tert-butyldimethylsilyloxy)-butyl carbonate (10) [7] Mono allyloxycarbonyl protected butandiol (871 mg, 5 mmol, 1 eq.) was dissolved in dry DMF (10 ml) and imidazole (1.02 g, 15 mmol, 3 eq.) was added. After cooling to 0 C TBDMSCl (1.13 g, 7.5 mmol, 1.5 eq.) was added dropwise to the reaction mixture. The mixture was stirred at room temperature over night until TLC showed full conversion of the starting material. The reaction mixture was poured into Et 2 O (25 ml) and the organic phase was washed with water (2 x 15 ml) and brine (1 x 15 ml). After drying over Na 2 SO 4, filtration and removal of the solvent under reduced pressure, the crude product was purified by means of flash chromatography on silica gel (gradient: hexanes/ethyl acetate 40:1 10:1). The carbonate was obtained as a colorless oil (1.27 g, 4.4 mmol, 88%). R f 0.55 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), (m,2h), 4.62 (dt, J = 5.8, 1.4 Hz, 2H), 4.17 (t, J = 6.6 Hz, 2H), 3.63 (t, J = 6.1 Hz, 2H), (m, 2H), (m, 2H), 0.89 (s, 9H), 0.04 (s, 6H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.2, 131.8, 119.0, 68.5, 68.3, 62.6, 29.1, 26.1, 25.5, 18.5, -5.2 ppm; IR (film) ν 2954 (w), 2930 (w), 1746 (s), 1463 (w), 1393 (w), 1248 (vs), 1095 (m), 959 (m), 833 (s), 774 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 231 (11), 187 (16), 159 (32), 145 (), 131 (24), 115 (100), 101 (29), 89 (18), 75 (61), 59 (17); HRMS (ESI, C 14 H 28 O 4 Si + Na + ) calcd.: ; found: Carbonic acid allyl ester 4-(tetrahydro-pyran-2-yloxy)-butyl ester (11) Mono allyloxycarbonyl protected butandiol (735 mg, 4.21 mmol, 1 eq.) and Dihydropyran (457 µl, 5.05 mmol, 1.2 eq.) were dissolved in dry DCM (15 ml). A solution of p-toluolsulfonic acid (15 mg, mmol, 0.02 eq.) in Et 2 O and the reaction mixture was stirred at room temperature over night. After TLC showed full conversion the mixture was washed with aqueous saturated NaHCO 3 (10 ml), brine (10 ml), and was dried over Na 2 SO 4. After filtration and removal of the solvent under reduced pressure the crude product was purified by means of flash chromatography on silica gel (gradient: hexanes/ethyl acetate 40:1 10:1). The THP ether was obtained as a colorless oil (793 mg, 3.07 mmol, 73 %). R f 0.60 (petroleum 7 Larhed, M.; Hallberg, A.; J. Org. Chem. 1997, 62, S-5

6 ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), (m, 2H), 4.62 (dt, J = 5.7, 1.2 Hz, 2H), 4.58 (t, J = 4.4 Hz, 1H), 4.19 (t, J = 6.6 Hz, 2H), (m, 2H), (m, 2H), (m, 6H), (m, 6H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.1, 131.7, 118.9, 98.8, 68.4, 68.0, 66.9, 62.3, 30.7, 26.0, 25.8, 25.5, 19.6 ppm; IR (film) ν 2942 (w), 1743 (s), 1454 (w), 1363 (w), 1246 (vs), 1121 (m), 1076 (m), 1033 (s), 1021 (s), 955 (m), 791 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 217 (3), 175 (10), 157 (8), 101 (20), 85 (100), 71 (15), 57 (7), 55 (21), 41 (29); HRMS (ESI, C 13 H 22 O 5 + Na + ) calcd.: ; found: Benzoic acid 4-allyloxycarbonyl-butyl ester (12) Mono allyloxycarbonyl protected butandiol (1.04 g, 6 mmol, 1 eq.) and dry pyridine (630 µl, 7.8 mmol, 1.3 eq.) were dissolved in dry THF (20 ml) and cooled to 0 C. At that temperature benzoyl chloride (871 µl, 7.5 mmol, 1.25 eq.) was added dropwise. The reaction mixture was stirred at room temperature over night. After TLC showed full conversion, ethyl acetate and water were added to the reaction mixture. The aqueous phase was extracted with ethyl acetate (3x 20 ml) and the combined organic phases were subsequently washed with sat. NaHCO 3 (10 ml), brine (10 ml), and were dried over Na 2 SO 4. After filtration and removal of the solvent under reduced pressure the crude product was purified by means of flash chromatography on silica gel (gradient: hexanes/ethyl acetate 40:1 10:1). The product was obtained as a colorless oil (1.20 g, 4.32 mmol, 72 %). R f 0.71 (petroleum ether/diethyl ether, 15:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 1H), (m, 2H), (m, 1H), 5.36 (dq, J = 17.2, 1.5 Hz, 1H), 5.27 (dq, J = 10.5, 1.3 Hz, 1H), 4.62 (dt, J = 5.7, 1.4 Hz, 1H), (m, 2H), (m, 2H), (m, 4H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 166.7, 155.2, 133.1, 131.7, 130.4, 129.7, 128.5, 119.1, 68.6, 67.7, 64.5, 25.7, 25.4 ppm; IR (film) ν 2960 (w), 1743 (m), 1715 (s), 1451 (w), 1241 (vs), 1109 (m), 1070 (w), 936 (m), 790 (m), 709 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 278 (8), 177 (40), 123 (9), 105 (100), 77 (16), 54 (9); HRMS (ESI, C 153 H 18 O 5 + Na + ) calcd.: ; found: Allyl 4-(fluorenymethyloxy)-butyl carbonate (13) The carbonate was obtained according to GP-A (8 mmol scale, using Fmoc chloride instead of Alloc chloride) as highly viscous oil (2.2 g, 5.52 mmol, 69 %). R f 0.64 (petroleum ether/diethyl ether, 20:1); 1 H NMR (300 MHz, CDCl 3 ): δ 7.77 (d, J = 7.5 Hz, 2H), 7.62 (d, J = 7.5 Hz, 2H), 7.41 (t, J = 7.4 Hz, 2H), 7.32 (td, J = 7.4, 1.1 Hz, 2H), (m, 1H), (m, 2H), (m, 2H), 4.41 (d, J = 7.3 Hz, 2H), 4.26 (t, J = 7.3 Hz, 1H), (m, 4H), (m, 4H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.2, 155.0, 143.4, 141.3, 131.6, 130.3, 127.9, 127.2, 126.4, 125.2, 120.1, 119.0, 69.8, 68.5, 67.5, 67.4, 46.8, 25.2 ppm; IR (film) ν 1738 S-6

7 (s), 1450 (w), 1237 (vs), 935 (m), 789 (m), 739 (s) cm -1 ; MS (ESI) m/z (%) 419 (100), 241 (19), 197 (29), 176 (16), 125 (4); HRMS (ESI, C 23 H 24 O 6 + Na + ) calcd.: ; found: O-Allyloxycarbonylmandelic acid ethyl ester (17) The carbonate was obtained according to GP-A as a colorless oil (4.70 g, 17.8 mmol, 89%); R f 0.72 (petroleum ether/diethyl ether, 15:1); [α] 20 D = (c = 1.13, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 3H), (m, 1H), 5.84 (s, 1H), 5.39 (app. dq, J = 17.2, 1.5 Hz, 1H), 5.29 (app. dq, J = 10.5, 1.3 Hz, 1H), 4.69 (d, J = 5.9 Hz, 2H), (m, 2H), 1.22 (t, J = 7.1 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 168.6, 154.3, 133.4, 131.3, 129.4, 128.8, 127.6, 119.2, 77.3, 69.1, 61.9, 14.0 ppm; IR (film) ν 2985 (w), 1742 (s), 1456 (w), 1371 (m), 1242 (s), 1209 (s), 1179 (s), 1027 (m), 956 (m), 786 (m), 695 (m) cm -1 ; MS (APCI, pos. ion) m/z (%) 265 (1), 223 (1), 163 (100), 147 (4), 135 (76), 107 (49), 91 (10); HRMS (APCI, C 14 H 16 O 5 + H + ) calcd.: ; found: ; ee determined by chiral HPLC : Chiracel OD-A, heptane/iso-propanol 96 :4, 1.0 ml/min, Inj.volume: 1 µl; t major = 6.03 min; t minor = 5.68, min, ee = 99%. 3-O-Allyloxycarbonyl-2(S)-O-benzyl-D-glycerol p-methylbenzenesulfonate (14) The carbonate was obtained starting from Toluene-4-sulfonic acid 2(S)-benzyloxy-3- hydroxy-propyl ester according to GP-A as a viscous oil (6.20 g, 14.8 mmol, 74%). R f 0.20 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 5H), (m, 2H), (m, 1H), (m, 2H), (m, 4H), 4.23 (dd, J = 11.8, 5.0 Hz, 1H), (dd, J = 11.8, 5.1 Hz, 1H), (m, 2H), 3.84 (app. quintett, J = 5.1 Hz, 1H), 2.43 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 154.6, 145.0, 137.3, 132.7, 131.3, 129.9, 128.5, 128.0, 127.9, 127.8, 119.1, 74.0, 72.5, 68.7, 68.3, 65.8, 21.7 ppm; IR (film) ν 1746 (s), 1598 (w), 1454 (w), 1361 (m), 1248 (s), 1175 (s), 959 (m), 813 (m), 787 (m), 665 (s), 552 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 420 (1), 379 (4), 273 (6), 212 (5), 173 (6), 155 (20), 142 (22), 107 (12), 91 (100); HRMS (ESI, C 21 H 24 O 7 S+ Na + ) calcd.: ; found: S-7

8 Methyl 6-O-allyloxycarbonyl-2,3,4-tri-O-benzyl-α-D-glucopyranoside (21) The carbonate was obtained according to GP-A (4 mmol scale, using TMEDA instead of pyridine) as an off-white solid (1.80 g, 3.28 mmol, 82%). mp. 71 C; R f 0.42 (petroleum ether/ethyl acetate, 4:1); [α] 20 D = 59.2 (c = 1.01, CH 2 Cl 2 ) 1 H NMR (300 MHz, CDCl 3 ): δ (m, 15H), (m, 1H), 5.34 (dd, J = 17.6, 1.8 Hz, 1H), 5.25 (dd, J = 11.0, 1.6 Hz, 1H), 5.00 (d, J = 11.4 Hz, 1H), 4.88 (d, J = 11.4 Hz, 1H), 4.82 (d, J = 11.4 Hz, 1H), 4.79 (d, J = 12.0 Hz, 1H), 4.65 (d, J = 12.0 Hz, 1H), 4.60 (d, J = 5.7 Hz, 2H), (m, 2H), (m, 2H), 4.00 (t, J = 9.2 Hz, 1H), 3.81 (dt, J = 10.2, 3.4 Hz, 1H), (m, 2H), 3.37 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.0, 138.8, 138.2, 138.0, 131.6, 128.6, 128.6, 128.5, 128.3, 128.2, 128.1, 128.0, 128.0, 127.8, 119.1, 98.2, 82.1, 79.9, 75.9, 75.2, 73.6, 68.7, 66.6, 55.4 ppm; IR (film) ν 2917 (w), 1966 (w), 1745 (s), 1456 (w), 1335 (m), 1277 (s), 1260 (s), 1043 (s), 954 (m), 734 (m), 695 (s) cm -1 ; MS (ESI, pos. ion) m/z (%) 271 (100), 469 (28), 379 (13), 181 (28), 91 (27); HRMS (ESI, C 32 H 36 O 8 + Na + ) calcd.: ; found: Allyloxycarbonylamino-2-allyloxycarbonyloxy-ethane (18) [8] The carbonate was obtained according to GP-A (10 mmol scale, using 2- aminoethanol (1 eq.), pyridine (2.25 eq.) and allyl chloroformiate (2 eq.)) as a colorless oil (1.93 g, 8.4 mmol, 84%). R f 0.45 (petroleum ether/ethyl acetate, 3:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 4H), 5.04 (s, 1H), 4.64 (dt, J = 5.9, 1.2 Hz, 2H), 4.57 (app. d, J = 5.5 Hz, 2H), 4.23 (t, J = 5.1 Hz, 2H), (m, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 156.2, 154.8, 132.7, 131.4, 119.3, 117.8, 68.7, 67.0, 65.8, 40.1 ppm; IR (film) ν 3344 (w), 1700 (s), 1523 (m), 1228 (vs), 1153 (m), 993 (m), 929 (m), 788 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 229 (4), 155 (7), 127 (48), 114 (22), 86 (23), 70 (20), 57 (13), 41 (100). (S)-2-Allyloxycarbonylamino-3-allyloxycarbonyloxy-propionic acid methyl ester (19) The carbonate was obtained according to GP-A (6 mmol scale, using serine methylester hydrochloride (1 eq.), pyridine (3.25 eq.) and allyl chloroformiate (2.1 eq.)) as a viscous yellowish oil (1.00 g, 3.48 mmol, 58%). R f 0.43 (petroleum ether/ethyl acetate, 5:1); [α] 20 D = (c = 1.94 M, CHCl 3 ) ; 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), 5.62 (d, J = 8.2 Hz, 1H), (m, 4H), (m, 2+1H), 4.54 (d, J = 11.2, 3.8 Hz, 1H), 4.45 (d, J = 11.2, 3.8 Hz, 1H), 3.79 (s, 3H) ppm ; 13 C NMR (125 MHz, CDCl 3 ) δ 169.7, 155.7, 154.6, 132.5, 131.3, 119.5, 118.1, 69.0, 67.4, 66.2, 53.4, 53.1 ppm ; IR (film) ν 3358 (w), 1746 (s), 1717 (s), 1519 (m), 1439 (w), 8 Gleim, C.E.; J. Am. Chem. Soc. 1954, 76, 107. S-8

9 1391 (w), 1228 (vs), 1058 (m), 932 (m), 787 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 287 (4), 256 (1), 228 (30), 213 (5), 186 (20), 172 (4), 144 (14), 126 (40), 41 (100); HRMS (ESI, C 12 H 17 NO 7 + Na + ) calcd.: ; found: (S)-2-Allyloxycarbonylamino-3-(4-allyloxycarbonyloxy-phenyl)-propionic acid methyl ester (20) [9] The carbonate was obtained according to GP-A (8 mmol scale, using tyrosine methylester hydrochloride (1 eq.), pyridine (3.25 eq.) and allyl chloroformiate (2.1 eq.)) as a viscous oil (1.78 g, 4.88 mmol, 61%); R f 0.16 (petroleum ether/ethyl acetate, 4:1); [α] 20 D = (c = 1.02 M; CH 2 Cl 2 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 4H), (m, 1H), (m, 1H), (m, 1H), (m, 1H), 5.29 (d, J = 17.4 Hz, 1H), 5.21 (d, J = 10.2, 1H), 5.19 (bs, 1H), (m, 2H), (m, 2H), (m, 1H), 4.56 (d, J = 5.4 Hz, 2H), 3.72 (s, 3H), 3.14 (dd, J = 14.1, 6.0 Hz, 1H), 3.09 (dd, J = 14.1, 6.0 Hz, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 171.8, 155.5, 153.4, 150.3, 133.6, 132.5, 131.1, 130.3, 121.2, 119.6, 117.9, 69.2, 65.9, 54.7, 52.4, 37.6 ppm; IR (film) ν 1758 (m), 1722 (m), 1509 (m), 1445 (w), 1365 (w), 1241 (s), 1216 (s), 1054 (m), 905 (w), 727 (w) cm -1 ; MS (EI, 70 ev) m/z (%)260 (3), 218 (24), 202 (2), 178 (3), 147 (100), 129 (5), 119 (10), 107 (20), 91 (14), 77 (8), 65 (2), 55 (4). S-IV General procedures for the Iron-catalyzed deprotection Conditions A: TBAFe catalyzed deprotection (GP-B) A 10 ml-schlenk tube was charged at room temperature with phosphine ligand (0.028 mmol, 2.8 mol%) and [Bu 4 N][Fe(CO) 3 (NO)] (10.3 mg, mmol, 2.5 mol%). The reaction vessel was evacuated and backfilled with nitrogen (2 x), before 1 ml of EtOH was added. The Schlenk tube was closed and the reaction mixture was stirred for 30 min at 80 C. After cooling to room temperature isopropyl thiol (188 µl, 2 mmol, 2 eq.) was added and the mixture turned from yellow to deep brown immediately. The alloc protected alcohol (1 mmol, 1 eq.) was added, the Schlenk was closed and the mixture was stirred at 40 C until TLC showed full consumption of the starting material. After removal of the volatiles under reduced pressure, the reaction mixture was directly subjected to flash chromatography on silica gel, using hexanes and ethyl acetate as the eluent. 9 Li, D.B.; Robinson, J.A.; Org. Biomol. Chem. 2005, 3, S-9

10 Conditions B: [Bu 4 N] 2 [((BnS)(NO) 2 Fe) 2 ]-catalyzed deprotection (GP-C) A 10 ml-schlenk tube was charged at room temperature with [(BnS)(NO) 2 Fe] 2 (6 mg, mmol) was dissolved in THF (0.3 ml) and potassium hydride (1 mg, mmol) was added. After the reaction mixture was stirred for 1 h at room temperature a deep green solution was obtained. Then Bu 4 NBr (8.1 mg, mmol) and EtOH (1ml) were added, followed by the addition of isopropyl thiol (188 µl, 2 mmol, 2 eq.) and alloc protected alcohol (1 mmol, 1 eq.). The Schlenk tube was closed and the mixture was stirred at 40 C until TLC showed full consumption of the starting material. After removal of the volatiles under reduced pressure, the reaction mixture was directly subjected to flash chromatography on silica gel, using hexanes and ethyl acetate as the eluent. S-V Spectroscopic data of deprotected alcohols (-)-Menthol (2) [10] The alcohol was obtained as a white solid (GP-B: mg, 0.99 mmol, 99%, GP-C: mg, 100%). m.p. 43 C [lit.: 43 C 11 ]; [α] 20 D = -50 (c = 10, EtOH); R f 0.46 (petroleum ether/diethyl ether, 5:1); 1 H NMR (300 MHz, CDCl 3 ): δ 3.41 (td, J = 10.4, 4.3 Hz, 1H), 2.17 (sept.d, J = 6.6, 2.8 Hz, 1H), (m, 1H), (m,1h), (m,1h), 1.49 (s, 1H), (m, 1H), (m, 1H), (m, 2H), 0.93 (d, J = 7.4 Hz, 3H), 0.91 (d, J = 6.4 Hz, 3H), (m, 1H), 0.81 (d, J = 6.7 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 71.6, 50.2, 45.2, 34.7, 31.8, 25.9, 23.2, 22.3, 21.1, 16.2 ppm; IR (film) ν 3244 (bm), 2954 (m), 2926 (s), 2869 (m), 1447 (m), 1312 (w), 1225 (w), 1172 (w), 1044 (s), 1025 (s), 995 (m) cm -1 ; MS (EI, 70 ev) m/z (%)155 (0.4), 138 (66), 123 (42), 109 (13), 95 (76), 81 (76), 71 (100), 55 (28), 41 (22). n-dodecanol (22) [12] The alcohol was obtained as a colorless oil (GP-B: mg, 0.98 mmol, 98%, GP- C: mg, 99%); R f 0.40 (petroleum ether/ethyl acetate, 5:1); 1 H NMR (500 MHz, CDCl 3 ): δ 3.64 (t, J = 6.4 Hz, 2H), (m, 2H), (m, 19H), 0.88 (t, J = 6.9 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 63.1, 32.8, 31.9, 29.7, 29.7, 29.6, 29.6, 29.5, 29.4, 25.8, 22.7, 14.1 ppm; IR (film) ν 3327 (b), 2921 (s), 2852 (s), 1465 (m), 1378 (w), 1056 (m), 721 (w) cm -1 ; MS (EI, 70 ev) m/z (%) 185 (0.2), 168 (20), 140 (24), 125 (10), 111 (31), 97 (60), 83 (90), 69 (92), 55 (100), 43 (87). 10 Beckmann, Pleissner, Liebigs Ann. Chem. 1891, 262, Pickard, Littlebury, J. Chem. Soc. 1912, 101, Zhang, J.; Gao, X.; Zhang, C.; Ma, J.; Zhao, D.; Synth. Comm. 2009, 39, S-10

11 2-Phenylethanol (23) [13] The alcohol was obtained as a colorless oil (GP-B: mg, 0.98 mmol, 98%, GP- C: mg, 95%); R f 0.53 (petroleum ether/ethyl acetat, 5:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 3H), 3.85 (t, J = 6.4 Hz, 2H), 2.86 (t, J = 6.6 Hz, 2H), 1.63 (s,1h) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 138.5, 129.0, 128.6, 126.5, 63.7, 39.2 ppm; IR (film) ν 3327 (w), 2941 (w), 1496 (w), 1453 (m), 1042 (s), 855 (w), 744 (m), 696 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 122 (44), 92 (64), 91 (100), 89 (3), 77 (5), 65 (10). Diphenylmethanol (24) [14] The alcohol was obtained as a white solid (GP-B: mg, 0.93 mmol, 93%, GP-C: mg); mp.: 68 C; R f 0.63 (petroleum ether/ethyl acetat, 5:1); 1 H-NMR (500 MHz, CDCl 3 ): δ = (m, 8 H), (m, 2H), 5.83 (s, 1 H), 2.25 (s, 1 H) ppm; 13 C-NMR (125 MHz, CDCl 3 ): δ = 143.8, 128.5, 127.6, 126.5, 76.2 ppm; IR (KBr): ν = 3252 (b), 3085 (m), 3056 (m), 3024 (m), 1596 (w), 1492 (m), 1445 (m), 1393 (w), 1343 (m), 1315 (m), 1272 (m), 1175 (m), 1015 (s), 916 (m), 830 (w), 759 (m), 738 (s), 696 (s) cm -1 ; MS (EI, 70 ev): m/z = 184 (40), 165 (10), 105 (100), 77 (60), 51 (20). Phenol (32) [15] The alcohol was obtained as a white solid (GP-B: 92.2 mg, 0.98 mmol, 98%, GP-C: 92.8 mg, 99%); mp.: 39 C; R f 0.10 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 1H), (m, 2H), 5.97 (s, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 155.2, 129.9, 121.2, ppm; IR (film) ν 3197 (bs), 1593 (s), 1498 (m), 1472 (s), 1369 (m), 1225 (vs), 1070 (m), 810 (m), 746 (vs), 688 (s) cm -1 ; MS (EI, 70 ev) m/z (%)94 (100), 65 (13), 55 (5), 47 (5), 39 (10). Methyl p-hydroxybenzoate (33) [16] The alcohol was obtained as a white solid (GP-B: mg, 0.96 mmol, 96%, GP-C: mg, 96%); mp. 128 C; R f 0.32 (petroleum ether/ethyl acetate, 10:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 2H), 5.79 (s, 1H), 3.89 (s, 3H) ppm; 13 Tamaru, Y.; Nagao, K.; Bando, T.; Yoshida, Z.; J. Org. Chem. 1990, 55, Macbeth; Mills; J. Chem. Soc. 1949, Bartoli, G.; Bosco, M.; Carlone, A.; Dalpozzo, R.; Locatelli, M.; Melchiorre, P.; Sambri, L.; J. Org. Chem. 2006, 71, Einhorn; Rothlauf; Liebigs Ann. Chem. 1911, 382, 263. S-11

12 13 C NMR (125 MHz, CD 3 OD) δ 174.8, 170.2, 132.8, 119.7, 115.2, 57.8 ppm; IR (film) ν 3027 (bw), 1685 (m), 1585 (m), 1499 (m), 1436 (m), 1257 (s), 1154 (m), 1101 (m), 773 (m), 644 (m), 624 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 152 (23), 121 (100), 93 (28), 65 (24), 53 (4); HRMS (ESI, C 12 H 12 O 5 + Na + ) calcd.: ; found: Cinnamyl alcohol (25) [17] The alcohol was obtained as a colorless oil (GP-B: mg, 0.82 mmol, 82%, GP-C: 96.8 mg, 72%); R f 0.31 (petroleum ether/diethyl ether, 4:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 5H), 6.63 (d, J = 15.3 Hz, 1H), 6.37 (dt, J = 16.0, 6.0 Hz, 1H), 4.33 (dd, J = 5.7, 1.5 Hz, 2H), 1.50 (s, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 136.8, 131.3, 128.7, 128.7, 127.8, 126.6, 63.8 ppm; IR (film) ν 3285 (b), (w), 1494 (w), 1447 (m), 1087 (m), 1067 (m), 1010 (s), 965 (s), 911 (w), 730 (s), 689 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 134 (82), 115 (80), 105 (68), 103 (38), 92 (100), 78 (79), 63 (23), 51 (39). 4-Hydroxymethyl-2,2-dimethyl-1,3-dioxolane (26) [18] The alcohol was obtained as a colorless oil (GP-B: mg, 0.96 mmol, 96%, GP-C: mg, 96%); R f 0.43 (petroleum ether/diethyl ether, 1:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), 4.04 (d, J = 8.2, 6.4 Hz, 1H), 3.80 (d, J = 8.2, 6.4 Hz, 1H), (m, 1H), (m, 1H), 1.82 (t, J = 6.2 Hz, 1H), 1.45 (s, 3H), 1.38 (d, J = 0.5 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 109.6, 76.3, 65.9, 63.2, 26.8, 25.4 ppm; IR (film) ν 3431 (w), 2987 (w), 1456 (w), 1371 (m), 1254 (m), 1211 (m), 1155 (m), 1046 (s), 970 (w), 839 (s) cm -1 ; MS (CI, pos. ion, react. gas CH 4 ) m/z (%)133 (100), 117 (100), 101 (34), 75 (8), 59 (30), 57 (11), 43 (29). 4-(tert-butyldimethylsilyloxy)butanol (27) The alcohol was obtained as a colorless oil (GP-B: mg, 0.85 mmol, 85%, GP-C: mg); R f 0.26 (petroleum ether/ethyl acetate, 5:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 4H), 2.06 (bs, 1H), (m, 4H), 0.90 (s, 9H), 0.07 (s, 6H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 63.5, 63.0, 30.4, 30.1, 26.1, 18.5, -5.3 ppm; IR (film) ν 3353 (w), 2929 (m), 2857 (m), 1472 (w), 1254 (m), 1098 (m), 833 (s), 773 (s) cm -1 ; MS (CI, pos. ion, reactand gas: CH 4 ) m/z (%) 205 (100), 187 (62), 147 (30), 133 (8), 105 (30), 101 (15), 73 (29); HRMS (ESI, C 10 H 24 O 2 Si+ H + ) calc d: , found: Barnes, R.; Graham, J.; Taylor, M.; J. Org. Chem. 1958, 23, Piantadosi, C.; Anderson, C. E.; Brecht, E. A.; Yarbro, C.V.; J. Am. Chem. Soc. 1958, 80, 6613 S-12

13 4-(tetrahydro-2H-pyran-2-yloxy)-butan-1-ol (28) [19] The alcohol was obtained as a colorless oil (GP-B: mg, 0.94 mmol, 94%, GP-C: mg, 97%); R f 0.16 (petroleum ether/ethyl acetate, 2:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), (m, 2H), (m, 2H), (m, 2H), 1.90 (s, 1H), (m, 6H), (m, 4H); 13 C NMR (125 MHz, CDCl 3 ) δ 98.9, 98.8, 67.6, 67.4, 62.9, 62.8, 62.4, 62.3, 30.8, 30.6, 30.2, 29.9, 26.6, 26.5, 25.5, 25.4, 19.6, 19.5 ppm; IR (film) ν 3401 (bw), 2939 (m), 1441 (w), 1352 (w), 1200 (w), 1137 (m), 1119 (m), 1060 (m), 1020 (s), 988 (m), 868 (w), 811 (w) cm -1 ; MS (CI, pos. ion, reactand gas CH 4 ) m/z (%) 175 (27), 101 (8), 91 (16), 85 (100), 73 (22), 55 (8). 4-Benzyloxybutan-1-ol (29) The alcohol was obtained as a colorless oil (GP-B: mg, 1 mmol, 100%, GP-C: mg, 97%); R f 0.11 (petroleum ether/ethyl acetate, 2:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 1H), (m, 2H), 4.37 (t, J = 6.5 Hz, 2H), 3.73 (t, J = 6.5 Hz, 2H), (m, 2H), (m, 2H), 1.53 (s, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 166.7, 132.9, 130.3, 129.6, 128.4, 64.8, 62.4, 29.3, 25.3 ppm; IR (film) ν 3365 (bw), 1714 (s), 1451 (w), 1269 (s), 1114 (m), 1069 (m), 1027 (m), 943 (w), 709 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 194 (3), 166 (9), 153 (4), 123 (65), 105 (100), 77 (32), 71 (8), 54 (8); HRMS (ESI, C 11 H 14 O 3 + Na + ) calcd.: ; found: Hydroxybutyl 9-fluorenylmethylcarbonate (30) [20] The alcohol was obtained as a colorless oil (GP-B: mg, 0.50 mmol, 50%, GP-C: mg, 58%); R f 0.58 (petroleum ether/ethyl acetate, 5:1); 1 H NMR (300 MHz, CDCl 3 ): δ 7.77 (d, J = 7.5 Hz, 2H), 7.62 (d, J = 7.5 Hz, 2H), 7.41 (td, J = 7.6, 0.8 Hz, 2H), 7.32 (td, J = 7.6, 1.1 Hz, 2H), 4.41 (d, J = 7.4 Hz, 2H), 4.26 (t, J = 7.4 Hz, 1H), 4.22 (t, J = 6.6 Hz, 2H), 3.70 (t, J = 6.4 Hz, 2H), (m, 2H), (m, 2H), 1.49 (s, 1H) ppm ; 13 C NMR (125 MHz, CDCl 3 ) δ 155.3, 143.4, 141.3, 127.9, 127.2, 125.2, 120.1, 77.2, 69.7, 68.0, 62.3, 46.8, 28.9, 25.2 ppm ; IR (film) ν 3343 (bw), 2951 (w), 1741 (m), 1450 (m), 1254 (vs), 1034 (w), 938 (w), 759 (m), 710 (m) cm -1 ; MS (EI, 70 ev) m/z (%) 312 (6), 138 (0.1), 196 (2), 179 (22), 178 (100), 165 (12), 139 (1), 89 (1) 19 Jones, R. C. F.; Jones, R. F.; Tetrahedron Letters 1990, 31, Williams, J. B.; Chapman, T. M.; Hercules, D. M.; Macromolecules 2003, 36, S-13

14 Ethyl (R)-2-hydroxy-2-phenylacetate (34) [21] The reaction was conducted according to procedure GP-B using only 1.05 eq. of isopropanthiol and stirring at 40 C for 5h. The alcohol was obtained as a colorless oil (GP-B: mg, 0.87 mmol, 79%, GP-C: mg, 93%); R f 0.29 (petroleum ether/ethyl acetate, 10:1); [α] 20 D = (c = 2, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 5H), 5.16 (s, 1H), (m, 2H), 3.46 (bs, 1H), 1.23 (t, J = 7.0 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 173.7, 138.5, 128.6, 128.4, 126.6, 73.0, 62.2, 14.1 ppm; IR (film) ν 3464 (bw), 1967 (w), 1729 (s), 1454 (w), 1207 (m), 1181 (s), 1092 (m), 1065 (s), 1012 (m), 731 (w), 696 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 180 (6), 107 (100), 79 (67), 77 (45), 51 (12); ee determined by chiral HPLC: Chircel OD-H, heptane/iso-propanol 90:10; 1ml/min; t major = 8.97 min, t minor = 6.14 min, ee = 99%. 3-Hydroxy-2(S)-O-benzyl-glycerol p-methylbenzenesulfonate (31) The alcohol was obtained as a colorless oil (GP-B : mg, 0.79 mmol, 79%, GP-C : mg, 74%); R f 0.19 (petroleum ether/ethyl acetate, 1:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 7H), 4.63 (d, J = 11.8 Hz, 1H), 4.54 (d, J = 11.8 Hz, 1H), 4.14 (d, J = 5.4 Hz, 2H), (m, 2H), (m, 1H), 2.45 (s, 3H), 1.75 (bs, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 145.0, 137.5, 132.7, 129.9, 128.6, 128.1, 128.0, 127.9, 77.2, 76.7, 68.6, 61.5, 21.7 ppm ; IR (film) ν 3440 (bw), 1598 (w), 1454 (w), 1354 (m), 1173 (s), 1096 (m), 1056 (m), 974 (m), 812 (m), 739 (m), 665 (s), 552 (s) cm -1 ; MS (CI, pos. ion, react. Gas : CH 4 ) m/z (%) 337 (48), 247 (11), 229 (5), 181 (26), 173 (9), 155 (7), 107 (35), 91 (100) ; HRMS (CI, pos Ion, 100 ev, C 17 H 20 O 5 S+ H + ) calcd.: ; found: ((2R,3R,4S,5R,6S)-3,4,5-Tris-benzyloxy-6-methoxy-tetrahydro-pyran-2-yl)-methanol (38) [22] 21 Roger, R.; J. Chem. Soc. 1932, Gama, Y.; Sasaki, M.; Yasumoto, M.; Ishigami, Y.; Chem. Lett. 1990, 11, S-14

15 The alcohol was obtained as a white solid (GP-B: mg, 0.86 mmol, 86%, GP-C: mg, 90%); mp. 56 C (lit.: C) 23 ; R f 0.39 (petroleum ether/ethyl acetate, 1.5:1); [α] 20 D (c = 1, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 15H), 4.99 (d, J = 10.9 Hz, 1H), 4.88 (d, J = 11.0 Hz, 1H), (m, 2H), 4.67 (d, J = 6.9 Hz, 1H), 4.63 (d, J = 5.9 Hz, 1H), 4.57 (d, J = 3.9 Hz, 1H), 4.00 (t, J = 9.1 Hz, 1H), (m, 3H), (m, 2H), 3.36 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 138.7, 138.1, 138.1, 128.5, 128.5, 128.4, 128.1, 128.0, 128.0, 127.9, 127.9, 127.6, 98.2, 81.9, 79.9, 77.4, 75.8, 75.0, 73.4, 10.7, 61.8, 55.2 ppm; IR (film) ν 3483 (w), 2871 (w), 1452 (m), 1361 (m), 1160 (m), 1084 (s), 1068 (s), 1026 (s), 911 (m), 740 (s), 697 (s) cm -1 ; MS (EI, 70 ev) m/z (%) 464 (0.3), 432 (6), 373 (99), 341 (43), 253 (25), 235 (22), 197 (12), 175 (17), 121 (8), 91 (100). N-(allyloxycarbonyl)-ethanolamine (35) [24] The alcohol was obtained as a colorless oil (GP-B: mg, 0.94 mmol, 94%, GP-C: mg, 88%); R f 0.23 (petroleum ether/ethyl acetate, 1:2); 1 H NMR (300 MHz, CDCl 3 ): δ z (m, 1H), 5.31 (dq, J = 17.4, 1.5 Hz, 1H), 5.22 (dq, J = 10.5, 1.3 Hz, 1H), 5.16 (bs, 1H), 4.58 (d, J = 5.6, 2H), 3.73 (t, J = 5.0 Hz, 2H), (m, 2H) ppm ; 13 C NMR (125 MHz, CDCl 3 ) δ 157.1, 132.7, 117.8, 65.8, 62.4, 43.5 ppm ; IR (film) ν 3327 (w), 2941 (w), 1691 (s), 1649 (w), 1530 (w), 1462 (w), 1253 (m), 1145 (m), 1064 (m), 993 (m), 930 (w), 777 (w) cm -1 ; MS (EI, 70 ev) m/z (%) 145 (4), 114 (100), 102 (6), 88 (23), 74 (40), 70 (61), 57 (31). (S)-2-Allyloxycarbonylamino-3-hydroxy-propionic acid methyl ester (36) [25] The alcohol was obtained as a colorless oil (GP-B: mg, 0.83 mmol, 83%, GP-C: 161 mg, 79%);R f = 0.43 (petroleum ether/ethyl acetate, 2:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 1H), 5.66 (bs, 1H), 5.33 (dd, J = 17.3, 1.5 Hz, 1H), 5.24 (dq, J = 10.5, 1.2 Hz, 1H), 4.60 (dt, J = 5.6, 1.3 Hz, 1H), (m, 1H), 4.01 (dd, J = 11.2, 3.9 Hz, 2H), 3.93 (dd, J = 11.2, 3.8 Hz, 2H), 3.80 (s, 3H), 1.98 (s, 1H) ppm ; 13 C NMR (125 MHz, CDCl 3 ) δ 170.9, 150.0, 132.4, 118.1, 66.1, 63.4, 56.0, 52.8 ppm ; IR (film) ν 3355 (bw), 1697 (s), 1520 (m), 1437 (w), 1338 (m), 1206 (s), 1057 (s), 995 (m), 931 (m), 776 (w) cm -1 ; MS (EI, 70 ev) m/z (%) 173 (41), 144 (100), 132 (84), 128 (15), 118 (14), 100 (14), 86 (37), 68 (27), 58 (31). (2S, 2 S)-3,3,3-Trifluoro-2-methoxy-2-phenyl-propionic acid (2 -allyloxycarbonyl-2 - methoxycarbonylethyl) ester (45) 23 Tatsuta et al., Carbohydr. Res. 1977, 54, Hung, D. T.; Nerenberg, J. B.; Schreiber, S. L.; J. Am. Chem. Soc. 1996, 118, Hanessian, S.; Xie, F.; Tetrahedron Letters 1998, 39, 733. S-15

16 (S)-2-Allyloxycarbonylamino-3-hydroxy-propionic acid methyl ester (36.6 mg, 0.18 mmol, 1 eq.) were dissolved in 2 ml of dry dichloromethane. After the addition of dry pyridine (29.1 µl, 0.36 mmol, 2 eq.) the solution was cooled to 0 C and (S)-(+)-α-Methoxy-α-(trifluormethyl)-phenylacetyl chloride was added. The mixture was stirred at room temperature over night and afterwards partitioned between 10 ml dichloromethane and 10 ml of water. The aqueous phase was extracted with DCM (3 x 10 ml). After drying over sodium sulphate and filtration, the solvent was removed in vacuo and the crude reaction mixture was subjected to coloumn chromatography on silica gel (petroleum ether/ethyl acetate = 2:1). The product was obtained as a colorless oil (71 mg, mmol, 94%); R f = 0.54 (petroleum ether/ethyl acetate, 2:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 5H), (m, 1H), 5.38 (d, J = 8.2 Hz, 1H), (m, 2H), (m, 2+1H), 4.58 (d, J = 5.8 Hz, 2H), 3.73 (s, 3H), 3.50 (q, J = 1.7 Hz, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 169.3, 166.1, 155.6, 149.0, 132.3, 131.8, 129.8, 128.6, 127.3, 124.3, 118.1, 66.2, 65.8, 55.4, 53.2, 53.0, 29.7 ppm; 19 F NMR (235 MHz, CDCl 3 ) δ ppm; IR (film) ν 3308 (w), 1751 (s), 1712 (w), 1684 (s), 1556 (m), 1452 (m), 1357 (w), 1281 (m), 1251 (m), 1222 (s), 1165 (s), 1107 (m), 1060 (m), 1032 (s), 985 (m), 956 (m), 917 (m), 730 (m), 698 (m) cm -1 ; MS (ESI, pos. ion) m/z (%) 442 (5), 257 (1), 208 (100), 186 (1); HRMS (ESI, C 18 H 20 F 3 N 1 O 7 + Na + ) calcd.: ; found: (S)-2-allyloxycarbonylamino-3-(4-hydroxy-phenyl)-propionic acid methyl ester (37) [26] The alcohol was obtained as a colorless oil (GP-B: 254 mg, 0.91 mmol, 91%, GP-C: mg, 94%); R f 0.22 (petroleum ether/ethyl acetate, 4:1); [α] 20 D = (c = 1.235, CH 2 Cl 2 ); 1 H NMR (300 MHz, CDCl 3 ): δ 6.97 (d, J = 8.6 Hz, 2H), 6.74 (d, J = 8.6 Hz, 2H), (m, 1H), 5.38 (s, 1H), (m, 2H), (m, 1H), 4.56 (d, J = 5.4 Hz, 2H), 3.73 (s, 3H), 3.06 (dd, J = 14.0, 5.8 Hz, 1H), 3.06 (dd, J = 14.0, 5.8 Hz, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 172.2, 155.6, 154.9, 132.5, 130.4, 127.5, 117.9, 115.6, 65.9, 54.9, 52.4, 37.5 ppm; IR (film) ν 3335 (w), 1966 (w), 1696 (s), 1514 (s), 1442 (m), 1345 (w), 1215 (s), 1173 (m), 1054 (m), 993 (m), 932 (w), 829 (w) cm -1 ; MS (EI, 70 ev) m/z (%) 220 (3), 178 (48), 162 (4), 147 (8), 135 (4), 107 (100), 77 (14). (S)-2-allyloxycarbonylamino-3-(4-tert-buytloxycarbonyl-phenyl)-propionic acid methyl ester (39) A 10 ml-schlenk tube was charged at room temperature with phosphine ligand (0.028 mmol) and [Bu 4 N][Fe(CO) 3 (NO)] (10.3 mg, 0.025, 2.5 mol%). The reaction vessel was evacuated and backfilled with nitrogen (2 x), before 1 ml of MeOH was added. The Schlenk tube was closed and the reaction mixture was stirred for 30 min at 80 C. After cooling to room temperature isopropyl thiol (188 µl, 2 26 Li, D. B.; Robinson, J. A.; Org. Biomol. Chem. 2005, 3, S-16

17 mmol, 2 eq.) was added and the mixture turned from yellow to deep brown immediately. The alloc protected tyrosine derivative (1 mmol, 1 eq.) was added, the Schlenk tube was closed and the mixture was stirred at 40 C until TLC showed full consumption of the starting material. After removal of the volatiles under reduced pressure, Boc 2 O (437 mg, 2.0 mmol, 2 eq.) and catalytic amounts of CBr 4 (33 mg, 0.1 mmol, 10 mol%) were added and the reaction was stirred neat at 60 C over night. The mixture was partitioned between ethyl acetate (15 ml) and H 2 O (10 ml) and the aqueous phase was extracted with ethyl acetate (3 x 10 ml). The combined organic phases were washed with sat. NaHCO 3 (10 ml) and brine (10ml) followed by drying with Na 2 SO 4. After filtration and removal of the solvent under reduced pressure, the crude product was subjected to flash chromatography on silica gel using petroleum ether and ethyl acetate as the eluent. The product was obtained as a colorless oil (337 mg, 0.89 mmol, 89% over 2 steps); R f 0.24 (petroleum ether/ethyl acetate, 5:1); [a] 20 D = (c = 1.50, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 4H), (m, 1H), 5.39 (s, 1H), (m, 2+1H), (m, 1H), 4.56 (d, J = 5.5 Hz, 1H), 3.72 (s, 3H), (m, 2H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 171.9, 151.8, 150.2, 133.2, 132.5, 130.2, 121.4, 117.9, 83.6, 65.9, 54.7, 52.4, 37.6, 27.7 ppm; IR (film) ν 3346 (w), 2984 (w), 1747 (s), 1694 (s), 1525 (m), 1514 (w), 1446 (w), 1369 (m), 1274 (s), 1257 (s), 1223 (s), 1145 (vs), 1041 (m), 1014 (m), 899 (m), 834 (m), 781 (m) cm -1 ; MS (ESI, pos. ion) m/z (%) 402 (100) [M+Na + ], 346 (43), 302 (3); MS (EI, 70 ev) m/z (%) 220 (4), 207 (2), 178 (49), 162 (3), 147 (9), 135 (4), 120 (2), 107 (100), 91 (4), 77 (13), 68 (3), 59 (2), 51 (5); HRMS (ESI, C 19 H 25 N 1 O 7 + Na + ) calcd.: ; found: S-VI Glycosylation reactions Phenyl 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranoside (40a) The thioglycoside was obtained according to a literature procedure [27]. At 0 C peracylated glucose (1.95 g, 5 mmol), was dissolved in dry dichloromethane (20 ml), followed by the addition of thiophenol (520 µl, 5.1 mmol) in one portion. After stirring for 5 min, boron trifluoro etherate (898 µl, 7.4 mmol) was added in one portion via syringe. The mixture was stirred at room temperature over night, until the reaction was quenched by the addition of saturated NaHCO 3 -solution (10 ml). After the gas evolution has stopped the phases were separated and the aqueous phase was extracted with dichlormethane (3 x 10 ml). The combined organic phases were washed with brine, dried over sodium sulfate, filtered and concentrated in vacuo. The crude product was purified by coloumn chromatography on silica gel using petroleum ether/ethyl acetate as the eluent. The thio glycoside was obtained as an off white solid (748 mg, 1.70 mmol, 34%); R f 0.40 (petroleum ether/ethyl acetate, 1.5:1); mp. 117 C, [a] 20 D = (c = 3, 27 Janczuk, A. J.; Zhang, W.; Andreana, P. R.; Warrick, J.; Wang, P. G.; Carbohydr. Res. 2002, 337, S-17

18 CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 2H), (m, 3H), 5.23 (t, J = 9.5 Hz, 1H), (m, 2H), 4.71 (d, J = 10.1 Hz, 1H), (m, 2H), (m, 1H), 2.09 (s, 3H), 2.08 (s, 3H), 2.02 (s, 3H), 1.99 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 170.6, 170.2, 169.4, 169.3, 133.1, 131.6, 128.9, 128.4, 85.7, 75.8, 74.0, 69.9, 68.2, 62.2, 20.8, 20.7, 20.6, 20.5 ppm; IR (film) ν 1738 (s), 1583 (w), 1439 (w), 1367 (m), 1214 (vs), 1086 (m), 1028 (s), 912 (m), 823 (m), 742 (m), 687 (m), 599 (m), 534 (m) cm -1 ; MS (EI, 70 ev) m/z (%)440 (0.1), 331 (20), 271 (3), 229 (3), 211 (4), 187 (4), 169 (100), 139 (13), 127 (33), 109 (98), 97 (13), 81 (9), 69 (5). Phenyl 2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside (40b) [28] To a solution of 2,3,4,6-tetra-O-benzyl-α-D-glucopyranose (1.2 g, 2.22 mmol, 1 eq.) and diphenyl disulfide (630 mg, 2.88 mmol, 1.3 eq.) in pyridine 10 ml, was added tributylphosphine (898 mg, 4.44 mmol, 2 eq.) at 0 C via syringe. After TLC showed complete conversion the reaction mixture was diluted with DCM and washed with water. After drying with Na 2 SO 4 and filtration the crude product was subjected to coloumn chromatography on silica gel using petroleum ether/ethal acetate as the eluent. The product was obtained as a mixture of α,β anomers (994 mg, 1.57 mmol, 70%), which was directly used in the glycosylation reaction. R f 0.30 (petroleum ether/ethyl acetate = 4:1); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 25H), 5.64 (d, J = 4.8 Hz, 0.18H, α anomer), (m, 9H, β anomer / PhCH 2 ), (m, 6H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 138.4, 138.3, 138.0, 137.9, 137.7, 133.8, 131.9, 131.5, 128.9, 128.5, 128.4, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.9, 127.8, 127.7, 127.7, 127.6, 127.4, 87.4, 87.0, 86.8, 82.6, 80.8, 79.1, 77.8, 77.5, 75.8, 75.4, 75.1, 73.4, 71.2, 69.0, 68.5 ppm; IR (film) ν 3088 (w), 3063 (w), 2903 (w), 2871 (w), 1956 (w), 1584 (w), 1497 (w), 1453 (w), 1356 (w), 1288 (w), 1215 (w), 1132 (m), 1075 (m), 1055 (s), 1027 (m), 988 (m), 899 (w), 832 (w), 731 (s), 692 (s), 654 (m) cm -1 ; MS (ESI, pos. ion) m/z (%) 655 (100) [M+Na + ], 650 (99) [M+NH + 4 ], 601 (5), 538 (2), 459 (8), 415 (2); HRMS (ESI, C 40 H 40 O 5 S+ Na + ) calcd.: ; found: ,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl trichloroacetimidate (40c) [29] To a solution of 2,3,4,6-tetra-O-benzyl-α-D-glucopyranose (1 g, 1.85 mmol, 1 eq.) in 10 ml of DCM were added trichloroacetonitrile (710µl) and NaH (157.3 mg, 3.93 mmol, 60w% in mineral oil) at room temperature. After TLC showed full conversion of the startin material, the mixture was filterd through a pad of silica and directly subjectes to coloumn chromatography on silica gel using petroleum ether/ethyl acetate as the eluent. 28 Fürstner, A.; Liebigs. Ann. Chem. 1993, Schmidt, R. R.; Michel, J.; Angew. Chem. 1980, 92, 763 S-18

19 The product was obtained as yellow viscous oil (892 mg, 1.3 mmol, 70%). R f 0.71 (petroleum ether/ethyl acetate, 4:1); 1 H NMR (300 MHz, CDCl 3 ): δ 5.87 (s, 1H), (m, 20H), (m, 2H), 6.52 (d, J = 3.4 Hz, 1H), 4.96 (d, J = 11.0 Hz, 1H), 4.85 (d, J = 10.5 Hz, 1H), 4.82 (d, J = 11.0 Hz, 1H), 4.75 (d, J = 11.6 Hz, 1H), 4.57 (d, J = 11.6 Hz, 1H), 4.60 (d, J = 11.8 Hz, 1H), 4.52 (d, J = 10.7 Hz, 1H), 4.46 (d, J = 11.8 Hz, 1H), 4.04 (t, J = 9.2 Hz, 1H), (m, 1H), (m, 3H), 3.66 (dd, J = 11.0, 2.3 Hz, 1H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 161.5, 138.8, 138.2, 138.1, 138.0, 128.6, 128.5, 128.5, 128.5, 128.2, 128.2, 128.1, 128.0, 128.0, 127.9, 127.9, 127.8, 127.8, 94.5, 91.4, 81.5, 79.5, , 75.8, 75.5, 73.6, 73.3, 73.0, 68.2, 27.1 ppm; IR (film) ν 3340 (w), 3031 (w), 2924 (w), 2867 (w), 2569 (b), 1967 (w), 1670 (m), 1496 (w), 1454 (m), 1361 (w), 1287 (w), 1209 (w), 1156 (w), 1069 (vs), 1027 (m), 995 (m), 966 (m), 903 (w), 827 (w), 793 (m), 733 (s), 695 (vs) cm -1 ; MS (ESI, pos. ion) m/z (%) 706 (31) [M+Na + ], 655 (12), 563 (100), 715 (8), 386 (1), 351 (1), 307 (2); HRMS (ESI, C 36 H 36 O 6 Cl 3 N+ Na + ) calcd.: ; found: Methyl O-(2,3,4,6-tetra-O-acetyl-p-D-glucopyranosyl)-( 1 6)-2,3,4-tri-O-benzyl α-dglucopyrunoside (41a) [29] A 10 ml-schlenk tube was charged at room temperature with trimesitylphosphine (0.028 mmol, 2.8 mol%) and [Bu 4 N][Fe(CO) 3 (NO)] (10.3 mg, 0.025, 2.5 mol%). The reaction vessel was evacuated and backfilled with nitrogen (2 x), before 1 ml of EtOH was added. The Schlenk tube was closed and the reaction mixture was stirred for 30 min at 80 C. After cooling to room temperature isopropyl thiol (40 µl, 0.4 mmol, 2 eq.) was added and the mixture turned from yellow to deep brown immediately. The alloc protected sugar derivative 21 (110 mg, 0.2 mmol, 1 eq.) was added, the Schlenk tube was closed and the mixture was stirred at 40 C until TLC showed full consumption of the starting material. After removal of the volatiles under reduced pressure, molecular sieves (120 mg) and the thiosugar 40a (96.8 mg, 0.22 mmol, 1.1 eq.) were added, the reaction vessel was evacuated for 30 min at room temperature, followed by the addition of 4 ml of dry dichlormethane. The mixture was stirred for another 30 min, before N-Iodsuccinimide (224 mg, 1 mmol, 5 eq.) was added and the solution was cooled to - 20 C. At this temperature trifluormethan sulfonic acid (2 µl) was added and the mixture was allowed to reach room temperature. After completion of the reaction as judged by TLC, the mixture was diluted with DCM (10 ml) and washed with sat. NaHCO 3 (8 ml), sat. Na 2 S 2 O 3 (8 ml) and H 2 O (8 ml). After drying over Na 2 SO 4 the solvent was removed in vacuo and the crude product was purified by column chromatography on silica gel using petroleum ether/ethyl acetate as the eluent. The product was obtained as a yellowish viscous oil (79.5 mg, 0.1 mmol, 50%). R f 0.32 (petroleum ether/ethyl acetate, 1.5:1); [a] 20 D = 3.5 (c = 0.99, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ (m, 15H), 5.17 (t, J = S-19

20 9.5 Hz, 1H), (m, 2H), 4.98 (d, J = 10.8 Hz, 1H), 4.86 (d, J = 10.8 Hz, 1H), 4.79 (d, J = 10.8 Hz, 1H), 4.78 (d, J = 12.2 Hz, 1H), 4.65 (d, J = 12.2 Hz, 1H), 4.57 (d, J = 3.5 Hz, 1H), 4.53 (d, J = 4.1 Hz, 1H), 4.51 (bs, 1H), 4.23 (dd, J = 12.2, 4.6 Hz, 1H), 4.11 (dd, J = 12.1, 2.0 Hz, 1H), 4.06 (d, J = 9.8 Hz, 1H), 3.97 (t, J = 9.4 Hz, 1H), (m, 1H), 3.69 (dd, J = 10.7, 4.7 Hz, 1H), (m, 1H), 3.51 (dd, J = 9.6, 3.5 Hz, 1H), 3.42 (t, J = 9.5 Hz, 1H), 3.36 (s, 3H), 2.04 (s, 3H), 2.03 (s, 3H), 1.99 (s, 3H), 1.95 (s, 3H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 170.7, 170.3, 169.4, 169.0, 138.7, 138.1, 138.1, 128.5, 128.5, 128.4, 128.2, 128.0, 127.9, 127.9, 127.7, 127.6, 100.7, 98.1, 82.0, 79.8, 77.6, 77.3, 77.0, 76.8, 75.7, 74.9, 73.4, 73.0, 71.8, 71.3, 69.7, 68.4, 68.2, 62.0, 55.2, 20.7, 20.7, 20.6, 20.6 ppm; IR (film) ν 2934 (w), 1749 (m), 1455 (w), 1365 (w), 1210 (m), 1027 (s), 904 (s), 736 (s), 697 (s), 651 (s), 598 (s) cm -1 ; MS (ESI, pos. ion) m/z (%) 817 (17) [M+Na + ], 757 (100), 697 (7), 655 (58), 595 (47), 533 (3), 515 (16), 487 (10), 469 (7), 379 (2), 363 (5). Methyl O-(2,3,4,6-tetra-O-benzyl-p-D-glucopyranosyl)-( 1 6)-2,3,4-tri-O-benzyl-Dglucopyranoside (41b) [30] A 10 ml-schlenk tube was charged at room temperature with trimesitylphosphine (0.028 mmol, 2.8 mol-%) and [Bu 4 N][Fe(CO) 3 (NO)] (10.3 mg, 0.025, 2.5 mol%). The reaction vessel was evacuated and backfilled with nitrogen (2 x), before 1 ml of EtOH was added. The Schlenk tube was closed and the reaction mixture was stirred for 30 min at 80 C. After cooling to room temperature isopropyl thiol (100 µl, 1 mmol, 2 eq.) was added and the mixture turned from yellow to deep brown immediately. The alloc protected sugar derivative 21 (274 mg, 0.5 mmol, 1 eq.) was added, the Schlenk tube was closed and the mixture was stirred at 40 C until TLC showed full consumption of the starting material. Thioglycosid coupling: After removal of the volatiles under reduced pressure, molecular sieves (200 mg) and the thiosugar 40b (443 mg, 0.7 mmol) were added, the reaction vessel was evacuated for 30 min at room temperature, followed by the addition of 10 ml of dry dichlormethane. The mixture was stirred for another 30 min, before N-Iodsuccinimide (787 mg, 3.5 mmol, 7 eq.) was added and the solution was cooled to -40 C. At this temperature trimethylsilyl trifluormethan sulfonate (13 µl, 0.07 mmol, 0.1 eq.) was added and the mixture was allowed to reach room temperature. After completion of the reaction as judged by TLC, the mixture was diluted with DCM (10 ml) and washed with sat. NaHCO 3 (10 ml), sat. Na 2 S 2 O 3 (10 ml) and H 2 O (8 ml). After drying over Na 2 SO 4 the solvent was removed in vacuo and the crude product was purified by column chromatography on silica gel using petroleum ether/ethyl acetate as the eluent. The product was obtained as a mixture of α/β anomers (405 mg, 0.41 mmol, 82%). Trichloracetimidate coupling: 30 Gama, Y.; Yasumoto, M.; Chem. Lett. 1993; 319. S-20