Tetrahydrofuran → Hexahydrophthalide

Participants

Reaction Conditions

Reaction Steps

At -5° C. and over a few minutes, a solution of 256 mg of ethyl chloroformate in 0.6 ml of tetrahydrofuran was added to a solution of 440 mg of the product of Step B'2 and 239 mg of triethylamine in 3.3 ml of tetrahydrofuran. The mixture was stirred for 30 minutes and then the precipitate was filtered off. The filtrate was added dropwise to a suspension of 235 mg of 95% sodium borohydride in 2.3 ml of water maintained at about 12° C. which was then left for 3 hours 30 minutes at ambient temperature. It was then cooled, acidified with 2N hydrochloric acid and extracted with methylene chloride. The extracts were dried, evaporated to dryness, purified by chromatography over silica (eluent: cyclohexane ethyl acetate, 65-35) to obtain 228 mg of (3a S, cis) hexahydro 1-(3H)-isobenzofuranone with a specific rotation of [α]D20 =-47° (c=0.6% in chloroform).

Provenance & Evidence