Triethylamine → 2-oxo-2-phenylethyl (3R,4S)-4-allyl-3-azido-1-[N-benzyl-N-(tert-butoxycarbonyl)glycyl]pyrrolidine-3-carboxylate

Participants

Reaction Steps

A stirred mixture of the crude racemic 2-oxo-2-phenylethyl (3R,4S)-4-allyl-3-azidopyrrolidine-3-carboxylate trifluoroacetate (Step 1, ˜1 mmol) and N-benzyl-N-(tert-butoxycarbonyl)glycine (337 mg, 1.27 mmol) in methylene chloride (9 mL) was treated with Et3N (0.495 mL, 3.55 mmol) followed by N,N,N′,N′-tetramethyl-O-(7-azabenzotriazol-1-yl)uronium hexafluorophosphate (HATU, 502 mg, 1.32 mmol), and the resulting mixture was stirred at room temperature and monitored by HPLC. At 1 h, the reaction was diluted with methylene chloride (20 mL), washed with water (20 mL), 1N aqueous HCl (10 mL), saturated aqueous NaHCO3 (20 mL) and saturated aqueous sodium chloride (10 mL), dried over Na2SO4, and concentrated under reduced pressure. Purification by silica gel chromatography (40 g column, 15-30% ethyl acetate in hexanes) gave 2-oxo-2-phenylethyl (3R,4S)-4-allyl-3-azido-1-[N-benzyl-N-(tert-butoxycarbonyl)glycyl]pyrrolidine-3-carboxylate (365 mg, 64%) as an amber gum which was used as is in the next step. LC-MS ESI+MS found for C30H35N5O6 m/z 562.3 (M+H), 584.3 (M+Na), 1H NMR (CDCl3, 400 MHz) δ 7.92 (m, 2 H), 7.66 (m, 1 H), 7.53 (m, 2 H), 7.30 (m, 5 H), 5.75 (m, 1 H), 5.52 (m, 2 H), 5.12 (m, 2 H), 4.58 (m, 2 H), 4.22-3.42 (m, 6 H), 2.60 (m, 1 H), 2.50 (m, 1 H), 2.12 (m, 1 H), 1.48 (s, 9 H).

Provenance & Evidence