Dicyclohexylcarbodiimide → 5-(3-Pyridinyl)-2-pentanone

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Reaction Conditions

Reaction Steps

To a cooled (-5° C.) solution of 32 g of the above enriched amine. 33 g of 1-hydroxybenzotriazole and 31.22 g of (R)-mandelic acid in 350 mL of dimethylformamide, was added a solution of 44.26 g of 1.3-dicyclohexylcarbodiimide in 150 mL of dimethylformamide and the mixture was stirred at -5° C. for 18 hours. After the precipitated dicyclohexylurea was removed by filtration, the filtrate was evaporated and the residue dispersed in 300 mL of cold 2N sodium hydroxide. The resulting solids were removed by filtration. Washed with dilute sodium hydroxide solution and with water and then dissolved in 500 mL of 2N hydrochloric acid. The acidic solution was extracted with dichloromethane (3×150 mL) to remove neutral impurities, then was basified with 10N sodium hydroxide and extracted with dichloromethane (6×300 mL). The dried extracts were evaporated to give 55 g of residual solid. Crystallization of the product from ethanol gave 25.6 g of [R-(R*,R)]-alpha- hydroxy-N-[1-methyl-4-(3-pyridinyl)butyl]benzeneacetamide, mp 141°-143° C. An additional 1.3 g of product, mp 141°-143° C., was obtained from the mother liquors.

Provenance & Evidence