作者:Roman Lagoutte、Céline Besnard、Alexandre Alexakis
DOI:10.1002/ejoc.201600707
日期:2016.9
The direct vinylogous Michael addition of unactivated α-Angelica lactone to enones under iminium activation using 9-amino-9-deoxy-epi-quinine as catalyst along with 2-hydroxy-1-naphthoic acid as co-catalyst has led to the formation of γ,γ-disubstituted butenolides in high yields, moderate-to-good diastereoselectivities and excellent enantioselectivities. The readily available catalytic system over-rides
使用 9-氨基-9-脱氧-表奎宁作为催化剂以及 2-羟基-1-萘甲酸作为助催化剂,未活化的 α-当归内酯在亚胺活化下直接与烯酮加成,导致形成γ,γ-二取代丁烯内酯的产率高、非对映选择性中等至良好且对映选择性优异。容易获得的催化系统克服了空间位阻,否则会导致顺式异构体的优先形成,以提供反异构体。在烯胺活化下,反异构体选择性地环化成六氢苯并呋喃-2(3H)-酮,它很容易与剩余的顺式异构体分离。还讨论了机制细节,包括亲核试剂的命运和非对映选择性的起源。