Department of Chemistry, McGill University, 801 Sherbrooke West, Montreal, QC H3A 0B8, Canada.
Org Lett. 2023 Feb 10;25(5):777-781. doi: 10.1021/acs.orglett.2c04269. Epub 2023 Jan 26.
Ethyl diazepane carboxylate catalyzes the oxy-Cope rearrangement of 4-hydroxy- and 4-alkoxy-1,5-hexadiene-2-carboxaldehydes via iminium ion activation. The resulting intermediate undergoes an intramolecular Michael reaction to furnish cyclopentane-containing products. The reaction proceeds with a range of substrates, including both cyclic and acyclic substrates, and tolerates substitution on the vinyl substituent. Substrates fused on a cycloalkane framework undergo net ring expansion/cyclopentannulation with a high degree of stereocontrol via chairlike transition states. The reaction extends iminium organocatalysis to the oxy-Cope rearrangement, embedded within a complexity-generating cascade transformation.
乙基二氮戊羧酸酯通过亚胺离子活化催化 4-羟基-和 4-烷氧基-1,5-己二烯-2-醛的氧-Cope 重排。所得中间体经历分子内迈克尔反应以提供含环戊烷的产物。该反应在一系列底物中进行，包括环状和非环状底物，并且对乙烯基取代基的取代具有耐受性。在环烷烃骨架上融合的底物通过椅式过渡态以高度的立体选择性经历净环扩张/环戊烷化。该反应通过复杂性生成级联转化将亚胺有机催化扩展到氧-Cope 重排中。
