Steroids. Part XXVII. Modification of 14α-methyl group in 4,4,14α-trimethylsteroids

Abstract

Lanost-8-enyl acetate has been converted via 3β-acetoxy-5α-lanostane-7,11-dione to 3β-acetoxy-7α-hydroxy-5α-lanostan-11-one which by the Barton reaction on the nitrite ester, followed by dehydration gave 3β-acetoxy-11-oxo-5α-lanost-8-en-14α-nitrile, which resisted hydrolysis to the corresponding acid. Lead tetra-acetate and iodine converted the 7α-hydroxy-11-ketone to the 7α-acetoxy-14α→ 7α-lactone and the 7α-acetoxy-7α,14α-ether. This ether was cleaved with pyridinium hydrochloride, which gave 3β-acetoxy-4,4-dimethyl-5α-cholest-8-en-11-one by rearrangement, together with the 3β,32-diacetoxy-11-oxo-5α-lanost-7-ene which was hydrolysed and oxidised to give the 4,4-dimethyl-5α-cholest-8-en-3,11-dione as the major product.