Trichloroethanol → tert.butyl(1R,cis)2,2-dimethyl-3-(2,2,2-trichloroethoxycarbonylethynyl)-cyclopropane-carboxylate

Participants

Reaction Steps

6.2 g of dicyclohexylcarbodiimide were introduced into a solution of 7.15 g of tert.-butyl (1R,cis) 2,2-dimethyl-3-(2-carboxyethynyl)-cyclopropane-carboxylate and 80 mg of 4 dimethylamino-pyridine in 35 ml of methylene chloride and the reaction mixture was stirred for 10 minutes after which 4.5 g of 2,2,2-trichloroethanol were added. The mixture was stirred for 1 hour and was filtered. The filtrate was washed with N hydrochloric acid, then with water until neutral, dried and evaporated to dryness. The 14 g of oil residue were chromatographed over silica gel and eluted with a 97-3 mixture of benzene-ethyl acetate to obtain 9 g of tert.butyl (1R,cis) 2,2-dimethyl-3-(2,2,2-trichloroethoxycarbonylethynyl)-cyclopropane-carboxylate melting at 70°-71° C.

Provenance & Evidence