Ethyl chloroformate → HCID 86736762, compound

Participants

Reaction Steps

2-(3-Amino-2-oxo-1-azetidinyl)-2-(2-thienyl)acetic acid (380 mg.) was suspended in dichloromethane (15 ml.), and to the suspension, there were added bis(trimethylsilyl) acetamide (0.60 g.) and N,N-dimethylformamide (0.25 ml.). The mixture was stirred at ambient temperature for 6 hours and insoluble materials were filtered off from the mixture, and to the filtrate, there was added bis(trimethylsilyl) acetamide (0.20 g.), whereafter the mixture was stirred for half an hour to prepare a dichloromethane solution. In the other hand, 4-(3-tert-butoxycarbonylamino-3-methoxycarbonylpropoxy)phenylglyoxylic acid (0.440 g.) was suspended in dichloromethane (10 ml.), and to the suspension, there were added triethylamine (0.120 g.) and N,N-dimethylbenzylamine (two drops). The mixture was stirred for a while to dissolve it, and a dichloromethane solution (15 ml.) containing ethyl chloroformate (0.125 g.) was added dropwise to the solution at -60° C. in the course of 3 minutes, whereafter the mixture was stirred at the same temperature for 5 minutes and then at -20° to -15° C. for 20 minutes to dissolve it. To this solution, there was dropwise added the dichloromethane solution, prepared above, at -60° C. in the course of 20 minutes, whereafter the mixture was stirred at the same temperature for half an hour, and then at -15° C. for half an hour. The stirring was continued at 0° C. for an hour and at 20° to 25° C. for additional 1.5 hours. The reaction mixture was evaporated to dryness under reduced pressure to give a residue, which was dissolved in an aqueous sodium bicarbonate. The resultant aqueous solution was washed with diethyl ether, adjusted to pH 5.5 with dilute hydrochloric acid and then washed with ethyl acetate. The aqueous solution was adjusted to pH 5.5 with dilute hydrochloric acid and extracted with ethyl acetate. The extract was evaporated to dryness under reduced pressure to give 2-[3-{4-(3-tert-butoxycarbonylamino-3-methoxycarbonylpropoxy)phenylglyoxyloylamino}-2-oxo-1-azetidinyl]-2-(2-thienyl)acetic acid (0.100 g.).

Provenance & Evidence