Citric Acid → Cbz-L-Phenylalaninal

Participants

Reaction Conditions

Reaction Steps

To a solution of 1.8 ml of dimethyl sulfoxide in 20 ml of dichloromethane cooled to -78° C. was added slowly 1.65 ml of oxalyl chloride. The solution was stirred for 10 min at -78° C. and a solution of 3.6 g (0.012 mol) of N-((benzyloxy)carbonyl)-L-phenylalaninol in 45 ml of dichloromethane was added slowly. The resulting solution was stirred at -78° C. for 15 min, then 1 min at 0° C., recooling to -78° C. and 7.6 ml of triethylamine was added over 10 min. After stirring at -78° C. for 25 min, 20 ml of cold 10% aq. citric acid solution was added. After warming to 0° C., 200 ml of ether and 55 ml of cold 10% citric acid added. The organic layer was separated by separatory funnel and washed repeatedly (5×60 ml) with water and finally with satd. NaCl solution. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated in vacuo at RT to give 3.51 g of the desired compound as an off-white solid.

Provenance & Evidence