Diisopropylethylamine → tert-butyl 3-((2-(2-((2S,5R)-6-(benzyloxy)-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carbonyl)hydrazinyl)-2-oxoethyl)(tert-butoxycarbonyl)amino)azetidine-1-carboxylate

Participants

Reaction Steps

DIPEA (14 g, 0.11 mol) was added to a 0° C. solution of tert-butyl 3-(tert-butoxycarbonyl(2-hydrazinyl-2-oxoethyl)amino)azetidine-1-carboxylate (15 g, 0.044 mol), (5R)-6-(benzyloxy)-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid (10 g, 0.036 mol) and HATU (15 g, 0.04 mol) in CH2Cl2 (250 mL). The mixture was allowed to warm to rt then was stirred at rt for 2 hrs. The mixture was quenched with saturated sodium chloride (50 mL) and the organic layer was separated. The water layer was extracted with EtOAc (3×). The combined organic layer was washed with saturated sodium chloride (2×), dried over Na2SO4, and concentrated. The residue was purified by silica gel column chromatography (gradient elution 0˜50% EtOAc/petroleum ether) to afford tert-butyl 3-((2-(2-((2S,5R)-6-(benzyloxy)-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carbonyl)hydrazinyl)-2-oxoethyl)(tert-butoxycarbonyl)amino)azetidine-1-carboxylate (18.5 g, 86%). ESI-MS (EI+, m/z): 603.3 [M+H]+.

Provenance & Evidence