Acetic Acid → 3-(Tert-butyldimethylsilyloxy)-4-chlorobenzoic acid

Participants

Reaction Steps

To a solution of 5.1 g of tert-butyldimethylsilyl 2-bromomethyl-3-(tert-butyldimethylsilyloxy)-4-chlorobenzoate and 3.52 g of N-[N-(tert-butoxycarbonyl)-L-seryl]-L-cysteine methyl ester in 55 ml of methylene chloride was added within 30 minutes, at 0° C., a solution of 1.59 g of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) in 15 ml of methylene chloride. Stirring was continued for 3 hours at 0° C., and subsequently the mixture was diluted with methylene chloride and stirred together with 100 ml of 1N aqueous acetic acid. The organic phase was washed with 10% sodium chloride solution, dried over sodium sulfate, and the solvent was evaporated in vacuo. The residue was chromatographed on MCI-Gel CHP20P using as eluent a mixture of acetonitrile-water containing 40-0% water. The product was eluted with pure acetonitrile. Evaporation of the solvent afforded 2.7 g of 2-[[[(R)-2-[(S)-1-tert-butoxyformamido )-3-hydroxypropionylamino]-2-methoxycarbonyl-ethyl ]thio]methyl]-3 -(tert-butyldimethylsilyloxy)-4-chlorobenzoic acid as a white foam.

Provenance & Evidence