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

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Reaction Steps

A solution of 2.0 g. of (+)-4,5-dihydro-1-[[ethoxy(4-phenylbutyl)phosphinyl]acetyl]-3-phenyl-1H-pyrazole-5-carboxylic acid, from Example 1(c), in 30 ml. of dry dimethylformamide under argon at room temperature is treated with 1.2 g. of ethyl 2-chloro-2-pivaloyloxyacetate, from part (a), and 0.58 g. of anhydrous potassium fluoride. After stirring for 48 hours the mixture is diluted with ethyl acetate and washed with water (3×). The organic fraction is dried (MgSO4) and concentrated in vacuo to give crude product. Flash chromatography on silica gel and elution with acetone/hexane (2:1) gives homogeneous (+)-4,5-dihydro-1-[[ethoxy(4-phenylbutyl)phosphinyl]acetyl]-3-phenyl-1H-pyrazole-5-carboxylic acid, 1-(2,2-dimethyl-1-oxopropoxy)-2-ethoxy-2-oxoethyl ester as an oil.

Provenance & Evidence