Studies on the BF3·Et2O catalyzed Baeyer–Villiger reaction of spiroketalic steroidal ketones
摘要:
During reactions of 23-oxosapogenins and the corresponding isomeric 22-oxo-23-spiroketals with MCPBA in the presence of BF3 center dot Et2O, equilibration occurs between the ketones. The Baeyer-Villiger type oxidation is followed by fragmentation to the dinorcholanic lactones and 3-methylbutyrolactone. The mechanistic aspects of these reactions in the 25R and 25S series are discussed. (C) 2010 Elsevier Inc. All rights reserved.
1H and 13C NMR characteristics of synthetic derivatives of steroid sapogenins
作者:Ignacio Vázquez-Ramírez、Mariana Macías-Alonso、Rafael O. Arcos-Ramos、Karen M. Ruíz-Pérez、Diana O. Solano-Ramírez、Martín A. Iglesias Arteaga
DOI:10.1016/j.steroids.2008.01.027
日期:2008.7
The full assignments of the (1)H and (13)CNMR signals of steroids bearing the 16beta,23:23,26-diepoxy side chain are provided. Differentiation of the diasterotopic H-26 pair was achieved with the aid of NOESY experiments. The main substituent and steric effects associated with this moiety and their influence on the chemicalshifts of the neighboring atoms are discussed.
提供了带有 16beta,23:23,26-diepoxy 侧链的类固醇的 (1) H 和 (13) C NMR 信号的完整分配。在 NOESY 实验的帮助下实现了非对映体 H-26 对的分化。讨论了与该部分相关的主要取代基和空间效应及其对相邻原子化学位移的影响。