Triphenylphosphonium bromide → 3-Phenyl-3-cyclopentenecarboxylic acid

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Reaction Conditions

Reaction Steps

3-(Benzoylmethyl)-4,5-dihydro-2(3H)-furanone (5.00 g, Step A) and triphenylphosphine hydrobromide (8.41 g) are mixed and heated to 170° C. in an oil bath under nitrogen for 1 hour. The mixture is cooled and powdered. The powder is dissolved in dimethylsulfoxide (50 mL) and diluted with tetrahydrofuran (30 mL). The solution is stirred under nitrogen and cooled in an ice-bath. Dimsyl sodium (25 mL of 2M, see Example D, Step C) is added dropwise over 20 minutes keeping the internal temperature below 14° C. The mixture is stirred at 25° C. for 2 hours and the solvents evaporated. The residue is treated with water (80 mL) containing saturated aqueous sodium bicarbonate (10 mL) and extracted with dichloromethane (3×50 mL). The extracts are washed with dilute aqueous sodium bicarbonate. The aqueous layers are washed with dichloromethane (30 mL) and acidified with concentrated hydrochloric acid. The aqueous layers are extracted with dichloromethane (3×50 mL), the extracts dried over magnesium sulfate, filtered, and evaporated to a brown oil. The oil is washed through silica gel (30 g) with 2:1 chloroform:ethyl acetate to give 3.1 g of 3-phenyl-3-cyclopentenecarboxylic acid as a brown solid.

Provenance & Evidence