566-99-4Relevant articles and documents
Epoxide Cleavage Reactions of 7α,8α- and 7β,8β-Epoxycholestanol Acetates
Eguchi, Sanae,Yamaguchi, Sanae,Furuya, Mitsuko,Morisaki, Masuo
, p. 2813 - 2818 (2007/10/02)
In a search for an alternative synthetic route to 32-oxygenated sterol derivatives such as 5, 7α,8α- and 7β,8β-epoxycholestanol acetate (9 and 10) were subjected to various conditions of epoxide cleavage.The trans-diaxial opening of the α-epoxide 9 with lithium/ethylamine gave the 7α-ol 11, whereas the 8β-ol 12 was produced from the β-epoxide 10 on reduction with lithium aluminum hydride.However, the trans-diaxal 8β-halo(or hydroxy)-7α-ols were not obtained at all on treatment of the α-epoxide 9 with various mineral acids or BF3-etherate in benzene.Under these conditions, the C-8 carbenium ion would be the intermediate, from which the 7-ketone 13 and a mixture of Δ6,8-, Δ7,14- and/or Δ8,14-diene compounds 16, as well as Δ8(9)- and Δ8(14)-7α-ol 14 and 4a, were produced.The latter allylic alcohol 4a, a possible synthetic precursor of 32-oxygenated sterol was prepared in 63percent yield when benzene was replaced with tetrahydrofuran in the BF3-etherate-catalyzed reaction of the α-epoxide 9.Keywords-epoxide cleavage; 32-oxygenated sterol; 7α,8α-epoxycholestanol acetate; 7β,8β-epoxycholestanol acetate; 3β-acetoxycholest-8(14)-en-7α-ol; reduction; acid treatment; boron trifluoride-etherate; long-range 13C-1H COSY
