Triethylamine → (2S,9S)-2-[(tert-Butoxycarbonyl)amino]-7-(carbobenzyloxy)-10-chloro-9-hydroxy-7-azadecanoic Acid tert-Butyl Ester

Participants

Reaction Steps

A solution of benzyl chloroformate (1.21 g, 7.09 mmol) in chloroform (10 mL) was added over a period of 15 min to an ice-cold solution of 12a (2.16 g, 5.46 mmol) in chloroform (40 mL) under an Ar atmosphere. After dropwise addition of triethylamine (1.11 g, 11.0 mmol) in chloroform (10 mL), the reaction mixture was stirred for 4.5 hours at rt. The reaction mixture was extracted with 1 N HCl (60 mL) and water (60 mL), dried, and concentrated. The residue was purified by flash chromatography (33% ethyl acetate/hexane) to give 13a (2.69 g, 93%) as a colorless oil: 1H NMR 61.30-1.83 (m, 6H), 1.44 (s, 9H), 1.45 (s, 9H), 3.20-3.64 (m, 6H), 3.93 (dd, 1H, J=8.2; 5.5), 4.00 (m, 1H), 5.12 (s, 2H), 7.26-7.40 (m, 5H); 13C NMR δ 24.1, 28.3, 28.8, 32.5, 49.4, 51.4, 52.2, 55.7, 68.4, 71.0, 80.4, 82.5, 129.0, 129.1, 129.6, 138.0, 157.5-158.4 (br), 158.1, 173.7; HRMS m/z calcd for C26H42ClN2O7 529.2681, found 529.2694. Anal. calcd. for C26H41ClN2O7: C 59.03, H 7.81, N 5.29. Found: C 59.09, H 7.78, N 5.21. [α]23D−21.8° (c 1.00, CH3OH).

Provenance & Evidence