Diastereoselective reactions of 1 4-bis(bromomagnesio)pentane with lactones and cyclic anhydrides
作者:P. Canonne、R. Boulanger、M. Bernatchez
DOI:10.1016/s0040-4020(01)80084-3
日期:1989.1
the stereochemical control of the intramolecular Grignard reaction can be attributed to the chelation between the groups in ortho position of the intermediate oxoalkyl magnesium compound. The alkoxy and the carboxylate seem to have an opposite effect. Furthermore, reactions of 1, 4-bis(bromomagnesio)pentane with non-aromatic cyclic anhydrides yield preferentially the trans diastereoisomer.
在芳族底物的情况下,1,4-双-(溴镁)戊烷与内酯和异酸酐的反应以显着的立体化学偏好进行,从而导致反式异构体的形成。另一方面,具有4H-3、1-苯并恶嗪-4-酮的那些主要提供顺式异构体,并且在邻苯二甲酸和1,2-萘二羧酸酐的情况下观察到更显着的立体选择性。分子内格氏反应在立体化学控制方面的这种差异可归因于邻位基团之间的螯合中间体氧代烷基镁化合物的位置。烷氧基和羧酸盐似乎具有相反的作用。此外,1,4-双(溴镁)戊烷与非芳族环状酸酐的反应优先产生反式非对映异构体。