Reaction Steps
Treatment of 12 (0.50 g, 1.26 mmol) in pyridine (1.02 mL, 12.61 mmol) and DCM (6.5 mL) with trifluoromethanesulfonic anhydride (0.32 mL, 1.90 mmol) followed by treatment of triflate residue in DMF (16 mL) with sodium azide (0.41 g, 6.31 mmol) according to the general procedure for introduction of the C-4 azide group gave compound 13 as colorless oil (0.42 g, 79%). Rf=0.32 (Hexane/EtOAc, 4:1, v:v). [α]27D=+13.1 (CHCl3, c=5.1 mg/mL). 1H NMR (300 MHz, CDCl3): δ 1.67 (t, 3H, J=7.5 Hz, SCH2CH3), 1.30 (d, 3H, J5,6=5.7 Hz, H-6), 2.10 (s, 3H, CH3C(O)CH2CH2C(O)O), 2.44-2.49 (m, 2H, CH3C(O)CH2CH2C(O)O), 2.57-2.67 (m, 4H, SCH2CH3, CH3C(O)CH2CH2C(O)O), 3.11-3.24 (m, 2H, H-4, H-5), 3.48 (t, J3,4=9.0, J2,3=9.0 Hz, H-3), 4.27 (d, 1H, J1,2=9.9 Hz, H-1), 4.68 (d, 1H, J=11.1 Hz, PhCH2), 4.71 (d, 1H, J=11.1 Hz, PhCH′2), 4.94 (dd, 1H, J1,2=9.9, J2,3=9.0 Hz, H-2), 7.22-7.29 (m, 5H, Harom); 13C NMR (75 MHz, CDCl3): δ 14.8 (SCH2CH3), 18.7 (C-6), 23.9 (SCH2CH3), 28.0 (CH3C(O)CH2CH2C(O)O), 29.8 (CH3C(O)CH2CH2C(O)O), 37.8 (CH3C(O)CH2CH2C(O)O), 67.7 (C-4), 72.2 (C-2), 74.9 (PhCH2), 75.1 (C-5), 82.3 (C-3), 83.2 (C-1), [127.9, 128.0, 128.2, 128.4, 137.5 (Carom)], 171.5 (CH3C(O)CH2CH2C(O)O), 206.1 (CH3C(O)CH2CH2C(O)O); MALDI-TOF/MS: m/z: found [M+Na]+ 444.1, C20H27N3O5S calcd for [M+Na]+ 444.15.
