Partial synthesis of 14α-hydroxy-5α-cholestan-3β-yl acetate

摘要

A convenient synthesis (in seven steps) of the 14α-hydroxy-5α-cholestan-3β-yl acetate (8, Scheme 2) is described. The synthesis starts from cholesteryl acetate (1) and involves the following transformations: (i) bromination/dehydrobromination of cholesteryl acetate (1); (ii) partial hydrogenation of the △~5-bond in the obtained 7-dehydrocholesteryl acetate (2); (iii) migration of the △~7-double bond in the thus formed compound 3 to the △~8(14)-position; (iv) isomerisation of the △~8(14)-unsaturated product 4 to the △~14-analogue 5 (v) epoxidation of the △~14-bond in 5; (vi) lithium aluminium hydride reduction of the 14α, 15α-epoxide 6; and (vii) partial acetylation of the 3β-hydroxyl function in the obtained diol 7 producing the final product 8. The total yield of the synthesis is ca. 18/100.