Dimethyl Sulfoxide → (Rac)-4-(1-methoxycarbonyl-3-oxo-propyl)-5-oxo-[1,4]diazepane-1-carboxylic acid benzyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 0.31 ml (3.60 mmol) of oxalyl chloride in 7.7 ml dichloromethane at −50 to −60° C. was added a solution of 0.53 ml (7.51 mmol) dimethylsulfoxide in 1.6 ml of dichloromethane within 10 min. The solution was stirred for 5 min and a solution of 1.14 (3.13 mmol) (rac)-4-(3-hydroxy-1-methoxycarbonyl-propyl)-5-oxo-[1,4]diazepane-1-carboxylic acid benzyl ester in 6.8 ml dichloromethane was added within 10 min. The mixture was stirred for 15 min and 2.18 ml (15.64 mmol) of triethylamine were added within 20 min. The suspension was stirred for 1¼ h and slowly warmed to 0° C. The reaction was neutralized with cold 10% aq. potassium dihydrogenphosphate solution (adjusted with 10% aq. potassium hydrogensulfate solution to pH 4-5) and extracted with diethyl ether (3×). The organic phases were washed with 10% aq. potassium dihydrogenphosphate solution, sat. aq. sodium hydrogencarbonate solution, 10% aq. sodium chloride solution, dried over Na2SO4 evaporated to yield 1.25 g (quantitative) of the title compound as yellow oil. MS: 363.2 (MH+).

Provenance & Evidence