Tributylphosphine → 20-(5,5-Dimethyl-1,3-dioxan-2-yl)-1alpha, 2alpha-epoxypregna-5,7-dien-3beta-yl acetate

Participants

Reaction Steps

A mixture of 10.3 mg (0.00997 mmole) of tris(dibenzylideneacetone)dipalladium(chloroform), 19.9 μl (0.0798 mmole) of tributylphosphine and 5 ml of dry 1,4-dioxane was stirred in an atmosphere of argon gas at room temperature for 10 minutes. To this mixture was added a solution of 43.6 mg (0.0798 mmole) of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxy-7α-methoxycarbonyloxypregn-5-en-3β-yl acetate in 2 ml of dry 1,4-dioxane, and the mixture was refluxed for 8 hours. The reaction mixture was cooled to room temperature and filtered through a glass filter with the aid of Florisil. The filtrate was concentrated under reduced pressure and the concentrate was purified by silica gel chromatography (eluent: ether-hexane=1:10, v/v) to give 17.4 mg of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxypregna-5,7-dien-3β-yl acetate. In addition, 15.3 mg of the starting compound 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxy-7α-methoxycarbonyloxypregn-5-en-3β-yl acetate was recovered. The yield of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxypregna-5,7-dien-3β-yl acetate was 71% based on consumed 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxy-7α-methoxycarbonyloxypregn-5-en-3β-yl acetate.

Provenance & Evidence