Intramolecular iminium ene reaction with Cu(I) catalysts: facile formation of 4-amino-3-methylenechromans from O-propargyl salicylaldehydes and dialkylamines
作者:Noriyoshi Arai、Takeshi Ohkuma
DOI:10.1016/j.tet.2011.01.007
日期:2011.3
Reaction of O-propargyl salicylaldehyde and related compounds with dialkylamines in the presence of copper(I) iodide gave 4-(alkylamino)-3-methylenechroman derivatives in good yields through the loss of one alkyl group of the dialkylamine. The reaction also worked well by employing 2-amino benzaldehyde derivatives to afford 4-(alkylamino)-3-methylene-1,2,3,4-tetrahydroquinolines. A deuterium-labeling experiment suggested that the a-hydrogen of the dialkylamine was transferred intramolecularly into the terminal methylene. This result indicated the reaction mechanism, which involved the formation of iminium ion between the aldehyde and the dialkylamine followed by ene-type C-C bond formation with inverse electron demand and hydrolysis. (C) 2011 Elsevier Ltd. All rights reserved.
An Improved Synthesis of Natural Product Inspired Chromenopyrrolizines and Chromenoindolizines Scaffolds: Rapid Access to the Diverse Pyrrolizine Analogs of Aza-Medicarpin and Tetracyclic Isolamellarin Core through a General Base and Metal Free Strategy
作者:Tabrez Khan、Virendra Kumar、Oindreela Das
DOI:10.1246/bcsj.20160205
日期:2016.11.15
improved synthesis for easy access to the natural product inspired chromenopyrrolizine and chromenoindolizine scaffolds is delineated. The strategy involves controlled thermal activation of diverse salicylaldehyde tethered dipolarophiles having the strategically stationed activating substituents with proline/pipecolic acid for the facile [3+2] cycloaddition of the in situ generated azomethine ylides and
Nickel‐Catalysed syn‐Selective Arylnickelation and Cyclisation of Ketone/Imine‐Tethered Terminal Alkynes with Arylboronic Acids
作者:Dáiríne Morgan、Hon Wai Lam、Patrick Guiry
DOI:10.1002/ejoc.202400445
日期:——
Herein the substrate scope of a nickel-catalysed syn-selective arylnickelation and cyclisation with arylboronic acids is expanded to include ketone and imine-tethered terminal alkynes. The reaction proceeds via a syn-aryl nickelation of a terminal alkyne followed by cyclisation of the resulting alkenylnickel species. Along with this the first enantioselective version of the reaction has been developed
本文中,镍催化的顺式选择性芳基镍化和芳基硼酸环化的底物范围扩大到包括酮和亚胺连接的末端炔烃。该反应通过末端炔烃的顺式芳基镍化进行,然后将所得烯基镍物质环化。与此同时,使用 PHIM 型 P,N 配体开发了该反应的第一个对映选择性版本。