Bromotrimethylsilane → (+)-4,5-dihydro-1-[[hydroxy(4-phenylbutyl)phosphinyl]acetyl]-3-phenyl-1H-pyrazole-5-carboxylic acid, 1-(2,2-dimethyl-1-oxopropoxy)-2-ethoxy-2-oxoethyl ester

Participants

Reaction Steps

A solution of 2.0 g of the diester product from part (b) in 25 ml. of dry dichloromethane under argon is treated at ambient temperature with 0.6 g. of bromotrimethylsilane. After stirring overnight, the volatiles are removed in vacuo and the residue, dissolved in ethyl acetate, is washed with 5% sodium dihydrogen phosphate, water and saturated brine. The organic fraction is dried (MgSO4) and concentrated in vacuo. The residue is triturated with acetonitrile or purified by flash chromatography to give (+)-4,5-dihydro-1-[[hydroxy(4-phenylbutyl)phosphinyl]acetyl]-3-phenyl-1H-pyrazole-5-carboxylic acid, 1-(2,2-dimethyl-1-oxopropoxy)-2-ethoxy-2-oxoethyl ester.

Provenance & Evidence