Unified Approach to Fused and Spirocyclic Oxindoles through Lewis-Acid-Promoted Opening of Spiroepoxyoxindoles with Allylsilanes: Application to the Formal Synthesis of (±)-Physovenine
作者:Brijesh M. Sharma、Mahesh Yadav、Rajesh G. Gonnade、Pradeep Kumar
DOI:10.1002/ejoc.201700259
日期:2017.5.10
A method for the C‐3 functionalization of 2‐oxindoles through the Lewis‐acid‐promoted opening of spiroepoxyoxindoles with allylsilanes to give Hosomi–Sakurai‐type products as well as spirocyclic oxindoles with all‐carbon quaternary centres has been developed. A formal synthesis of (±)‐physovenine was accomplished in five steps using this approach.
Reversal of Selectivity in C3-Allylation and Formal [3 + 2]-Cycloaddition of Spiro-epoxyoxindole: Unified Synthesis of Spiro-furanooxindole, (±)-<i>N</i>-Methylcoerulescine, (±)-Physovenine, and 3a-Allylhexahydropyrrolo[2,3-<i>b</i>]indole
作者:Saumen Hajra、Sayan Roy、Subrata Maity
DOI:10.1021/acs.orglett.7b00420
日期:2017.4.21
a formal [3 + 2]-annulation reaction of spiro-epoxyoxindoles have been developed and can be accessed simply by changing the reaction conditions. This method has been successfully employed for the synthesis of spiro(pyrrolidinyloxindole), 3a-allylhexahydropyrrolo[2,3-b]indole, and furanoindoline.
已经开发出有效的路易斯酸催化的区域选择性C 3-烯丙基化和螺-环氧氧吲哚的正式[3 + 2]-环化反应,并且可以通过改变反应条件来简单地获得。该方法已成功地用于合成螺(吡咯烷基二氧杂吲哚),3a-烯丙基六氢吡咯并[2,3- b ]吲哚和呋喃二氢吲哚。