Ethylamine → Bimatoprost

Participants

Reaction Conditions

Reaction Steps

250 mL of methylene chloride were added to 12.3 g of (Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-((R)-3-hydroxy-5-phenyl-pent-1-enyl)-cyclopentyl]-hept-5-enoic acid (compound (7), MW=402.54; 26.1 mmol; 1 equivalents). The solution is cooled to −10° C. At this temperature 5.1 g of triethylamine (MW=101.19; 50.4 mmol; 1.9 equivalents) and 5.1 g of ethyl chloroformate (MW=108.52; 48.1 mmol; 1.8 equivalents) were added and the mixture was stirred for two hours. A solution of 2.3 g of ethylamine (MW=45.08; 2.0 equivalents) in 10 mL methylenehloride was added. After stirring the reaction mixture for two hours at −10° C., the mixture was warmed to room temperature. The reaction was quenched by addition of 250 mL of water and the pH is adjusted to 2.0 with 1M aqueous hydrochloric acid. After separation of the layers, the organic layer was washed with 250 mL of saturated aqueous sodium bicarbonate, water and brine. After filtration the solution was concentrated under reduced pressure to give 13.1 g of bimatoprost crude (yield: 89%; as determined by NMR). Bimatoprost crude was purified as described below.

Provenance & Evidence