Hiroko Furuyama

A facile ring-opening reaction of cyclobutenes: application to a synthesis of vitamin D3

Abstract The extraordinary accelerating effects of arylsulfinyl, arylsulfonyl, and diphenylphosphinoyl carbanion substituents for cyclobutene ring-opening reaction of bicyclo[4.2.0]-oct-l(6)-ene derivatives are described. The scope and limitation of this new type of reaction, and the application of the dienes so generated by this method for the synthesis of vitamin D 3 , are also discussed.

Stereoselective synthesis of the 20-hydroxyecdysone side chain

A new procedure for the construction of the 20-hydroxyecdysone-type side chain starting from 20-oxopregnane is described. The stereoselective reduction of the lactone (15) as a key reaction to give the δ-lactone (17) and the γ-lactone (18), under various conditions has also been investigated. A stereoselective synthesis of (20R,22R)-5α-cholestane-3β,20,22,25-tetraol (20) is described.

An efficient synthesis of cholanic acids from 20-ketopregnanes

Abstract An efficient synthesis of 3β-hydroxy-5α-cholanic acid (8) and 3β-hydroxy-Δ5-cholanic acid (16) was carried out starting from 5α-dihydropregnenolene (1) and pregnenolone (9). The monoacetates (3 and 11), prepared by Grignard reaction of 1 and 9 with 3,3-ethylenedioxypropylmagnesium bromide followed by acetylation, were dehydrated selectively to give the Δ20(22)-compounds (4 and 12) which on hydrogenation followed by acid treatment and Jones oxidation yielded 8 and 16, respectively.

Stereocontrolled synthesis of the ecdysone side chain via a furan derivative

A stereocontrolled synthesis of (20 R,22 R)-5β-cholestane-3β,20,22,25-tetraol (8) from a furan derivative of pregnanolone is described.