Stereoselective Synthesis of Isoquinuclidines through an Aza-[4 + 2] Cycloaddition of Chiral Cyclic 2-Amidodienes
作者:Li-Chao Fang、Richard P. Hsung
DOI:10.1021/ol500390a
日期:2014.3.21
A highly stereoselective aza-[4 + 2] cycloaddition of chiral cyclic 2-amidodienes with N-sulfonyl aldimines is described. While this Lewis acid promoted heterocycloaddition provides an efficient strategy for constructing optically enriched isoquinuclidines, it is mechanistically intriguing. The cycloaddition favored the endo-II pathway in the absence of a viable bidentate coordination. This represents
描述了手性环状2-酰胺二烯与N-磺酰醛亚胺的高度立体选择性氮杂-[4+2]环加成。虽然这种路易斯酸促进的杂环加成为构建光学富集的异奎宁环提供了有效的策略,但它在机制上很有趣。在缺乏可行的二齿配位的情况下,环加成有利于内切 II途径。这代表了与全碳环加成中获得的预期内切 I选择性的意外转变。