27 Withanolidesの合成研究

概要

論文の詳細を見る
To obtain further information on the reactions and stereo-chemistry of steroids, synthesis of withanolides was investigated. As a model compound, the AB ring moiety of withaferin A (1), anti-tumor steroid, was synthesized from cholesterol. Dienone 7 was derived to 6α-hydroxy-dienone 18, which was converted to 31. The analogues, 19, 21, 22, 23, 36b, 37b and 40b, which have the similar functionalities in ring A/B as those of 1, have been synthesized through the key intermediate dienones 7 and 24. For the synthesis of side chain of 1-3, the coupling reaction of C-22-aldehyde with α,β-unsaturated esters was carried out. Reaction with α,β-unsaturated esters which have methyl groups at both α and β carbons gave γ-coupling product 46. This has the identical structure with 2 and 3 except for the stereochemistry at C-22 position. The stereochemistry of electrophilic reactions on C-22-ene 48 was investigated inorder to find a method of stereospecific introduction of 22R-hydroxy group.
天然有機化合物討論会の論文
1975-10-01