[3,3]-Claisen rearrangements in 24α-methyl steroid synthesis
作者:Vladimir A. Khripach、Vladimir N. Zhabinskii、Olga V. Konstantinova、Natalya B. Khripach、Andrey P. Antonchick、Bernd Schneider
DOI:10.1016/s0039-128x(02)00007-7
日期:2002.6
campesterol starting from stigmasterol. The proposed approach is based on Claisen rearrangement of Delta23-22-allylic alcohols with various configurations of the 22-hydroxy group and geometry of the Delta23-double bond. It allows complete use of the starting steroid for preparing 24alpha-methyl derivatives. It was possible to partially control the stereochemistry at C-25. Hydrogenation of the Delta22-double
Ireland–Claisen rearrangement of steroidal Δ23-22-alcohols: an application to Δ22,25-24-alkyl steroid synthesis
作者:Vladimir A. Khripach、Vladimir N. Zhabinskii、Olga V. Konstantinova、Natalya B. Khripach
DOI:10.1016/s0040-4039(00)00900-x
日期:2000.7
chain, providing the possibility of stereocontrol at C-3 has been described. Its usefulness has been examined for Δ22,25-24-alkyl steroid synthesis. The proposed approach is based on the Ireland–Claisenrearrangement of Δ23-22-alcohols followed by C-25 silylation of the formed ester and Peterson olefination as the final step.