Enantio- and Diastereoselective Formal Hetero-Diels-Alder Reactions of Trifluoromethylated Enones Catalyzed by Chiral Primary Amines
作者:Yong-Jun Lin、Li-Na Du、Tai-Ran Kang、Quan-Zhong Liu、Ze-Qin Chen、Long He
DOI:10.1002/chem.201501897
日期:2015.8.10
Enantioselective formal hetero‐Diels‐Alder reactions of trifluoromethylated enones and 2‐amino‐1,3‐butadienes generated in situ from aliphatic acyclic enones and chiral primary amines are reported. The corresponding tetrahydropyran‐4‐ones are formed in up to 94 % yield and with up to 94 % ee. The reaction was carried out through a stepwise mechanism, including initial aminocatalytic aldol condensation
据报道,由脂族无环烯酮和手性伯胺原位生成的三氟甲基化的烯酮和2-氨基-1,3-丁二烯的对映体选择性杂Diels-Alder反应。形成相应的四氢吡喃-4-酮,产率高达94%,ee高达94% 。该反应是通过逐步机理进行的,包括将2-氨基-1,3-丁二烯与三氟甲基化羰基进行氨基催化醛醇缩合反应,然后进行分子内的氧杂-Michael加成反应。在过渡状态中,两个NMR调查和理论计算表明,质子化的叔胺可以有效激活三氟甲基酮的羰基,以促进通过N个氢键相互作用加法处理H⋅⋅⋅F和N H⋅⋅⋅O同时,因而对于氨基-1,3-丁二烯的至活化的三氟甲基酮的方法提供了一种手性环境中,从而导致高的对映选择性。