Department of Chemistry, Indian Institute of Technology Jammu Jagti, NH 44, Nagrota Bypass, Jammu, J&K 181221, India.
Org Biomol Chem. 2021 May 19;19(19):4193-4212. doi: 10.1039/d1ob00409c.
The imine umpolung is a relatively new and interesting strategy, especially in catalytic asymmetric synthesis. A significant development in organo- and transition metal-catalyzed umpolung of imines took place only in the recently concluded decade. A majority of the reports on the asymmetric umpolung of imines involve the initial generation of 2-azaallyl anion intermediates with the chiral catalysts, which serve as a significant driving force for the umpolung addition/substitution reactions. A variety of organocatalysts such as bifunctional cinchona alkaloids including squaramides and thioureas, chiral BINOL derived phosphoric acids, phase transfer catalysts (PTCs), phosphines, and transition metal-complexes of iridium, copper and palladium have been employed to achieve the excellent level of asymmetric induction in such types of umpolung reactions. The asymmetric imine umpolung strategy has been applied successfully to synthesize synthetic amino-acid derivatives and other useful chiral amines, including drugs and potentially bioactive molecules. This review summarizes all the significant recent development in catalytic umpolung reactions of imines involving a 2-azaallyl anion intermediate.
亚胺反极性转换是一种相对较新且有趣的策略，尤其在催化不对称合成中。在过去十年中，有机和过渡金属催化的亚胺反极性转换取得了重大进展。大多数关于亚胺不对称反极性转换的报道都涉及手性催化剂初始生成 2-氮丙啶烯阴离子中间体，这是反极性加成/取代反应的重要驱动力。各种有机催化剂，如双功能金鸡纳生物碱（包括联萘酚衍生的手性磷酸、相转移催化剂 (PTC)、膦和铱、铜和钯的过渡金属配合物），已被用于实现此类反极性反应的出色不对称诱导水平。不对称亚胺反极性策略已成功应用于合成合成氨基酸衍生物和其他有用的手性胺，包括药物和潜在的生物活性分子。本文综述了涉及 2-氮丙啶烯阴离子中间体的催化反极性转换反应的最新进展。
