Remote functionalization reactions in steroids.

Design and synthesis of 23,24-dinoroleanolic acid derivatives, novel triterpenoid-steroid hybrid molecules

Chiroptical properties of binuclear rhodium complexes of lanostane alcohols.

The literature on the distribution in nature, structural variations, isolation, identification, and biosynthesis issues of triterpenoids with a five-membered A-ring was reviewed. The principal trends in approaches to the synthesis of structural analogs of such compounds were discussed. Information on the biological activity of natural and semi-synthetic A-pentacyclic triterpenoids was presented.

Triterpenoids with a Five-Membered a-Ring: Distribution in Nature, Transformations, Synthesis, and Biological Activity

Synthesis, cytotoxic evaluation, and molecular docking studies of the semi-synthetic "triterpenoid-steroid" hybrids.

3,4-Seco-5α-lanost-4(30)-en-3-onitrile, obtained by ‘second-order’ Beckmann cleavage of 3-hydroxyimino-5α-lanostane, has been used as an intermediate in the conversion of lanosterol into 14α-methylcholest-4-en-3-one.

Steroids. Part XXXV. Removal of the 4-methyl groups in 4,4,14α-trimethyl-steroids: conversion of lanosterol into 14α-methylcholest-4-en-3-one

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.

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

5β,14α-Androstan-17-one was converted into the 17α-ethynyl derivative, which was hydrated to give 17β-hydroxy-5β,14α,17α-pregnan-20-one and its rearrangement product 17aα-hydroxy-17aβ-methyl-5β,14α-D-homoandrostan-17-one.

N. W. Hughes

Papers

Steroids. Part XXXV. Removal of the 4-methyl groups in 4,4,14α-trimethyl-steroids: conversion of lanosterol into 14α-methylcholest-4-en-3-one

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

Steroids. Part XXXIV. 17β-Hydroxy-5β,14α,17α-pregnan-20-one and related compounds

Modification of the 14α-methyl group in lanosterol

The structure of digacetigenin