Methyl propiolate → HCID 53842172, compound

Participants

Reaction Steps

To a magnetically-stirred solution of 3.9 ml (45 mmol) of methyl propiolate and 150 ml of dry methylene chloride under an argon atmosphere was added by syringe 58 ml (107 mmol) of 25% ethylaluminum dichloride in toluene, followed as rapidly as possible by a solution of 12.0 g (30 mmol) of Z-pregna-5,17(20)-diene-1α,3β-diol diacetate in 150 ml of dry methylene chloride. The temperature rose to 35° after the catalyst addition. After 1.75 hr., the yellow reaction solution was poured into a well-stirred, ice-cold 1 l. of saturated sodium dihydrogen phosphate solution. About 600 ml of ethyl acetate was added, and the phases were separated. The aqueous phase was extracted with 2×600 ml of ethyl acetate, and the organic phases were washed in a countercurrent manner with 500 ml of water and 500 ml of brine, dried (Na2SO4), filtered and evaporated to give 15.32 g of crude product. High-pressure liquid chromatography on 1 kg of silica gel using 9:1 hexane--ethyl acetate for elution afforded after three passes 12.9 g (89%) of 1α,3β-diacetyloxychola-5,16,22-trien-24-oic acid methyl ester as an amorphous solid.

Provenance & Evidence