Inverse Electron-Demand Aza-Diels–Alder Reaction of Cyclic Enamides with 1,2-Diaza-1,3-dienes in Situ Generated from α-Halogeno Hydrazones: Access to Fused Polycyclic Tetrahydropyridazine Derivatives
efficient inverse electron-demand aza-Diels–Alder reaction of cyclic enamides and 1,2-diaza-1,3-dienes, which could be readily formed in situ from α-halogeno hydrazones and a base, has been successfully developed. With the developed approach, a wide range of fusedpolycyclic tetrahydropyridazines were smoothly obtained in up to 99% yield under benign reaction conditions. This reaction concept was also extended
Brønsted Acid Catalyzed [3 + 2]-Cycloaddition of Cyclic Enamides with <i>in Situ</i> Generated 2-Methide-2<i>H</i>-indoles: Enantioselective Synthesis of Indolo[1,2-<i>a</i>]indoles
作者:Kalisankar Bera、Christoph Schneider
DOI:10.1021/acs.orglett.6b02898
日期:2016.11.4
An efficient formal [3 + 2]-cycloaddition toward the highly diastereo- and enantioselectivesynthesis of indolo[1,2-a]indoles is disclosed. A chiral BINOL-derived phosphoric acid catalyzed the highly enantioselective conjugate addition of cyclic enamides to in situ generated 2-methide-2H-indoles and subsequent aminalization to give rise to acetamide-substituted indolo[1,2-a]indoles carrying three contiguous
公开了向吲哚[1,2- a ]吲哚的高度非对映和对映选择性合成的有效形式[3 + 2]-环加成反应。手性BINOL衍生的磷酸催化环烯酰胺的高对映选择性共轭加成反应,使其原位生成2-甲基2 H-吲哚并随后进行醛化,生成带有3个连续氨基酸的乙酰胺取代的吲哚[1,2- a ]吲哚立体定向中心。重要的是,这些产物形成为单一非对映异构体,并具有优异的产率和对映选择性。在环境温度下温和的反应条件,对乙酰氨基基团的轻松除去以及放大的可能性凸显了该方法的实用性。
Efficient construction of polycyclic chromans through 4-methylbenzenesulfonic acid mediated domino 1,6-addition/oxa-Mannich reaction of ortho-hydroxyphenyl substituted para-quinone methides and cyclic enamides
A practical TsOH promoted novel domino 1,6-addition/oxa-Mannich reaction of cyclic enamides and ortho-hydroxyphenyl substituted para-quinone methides was established smoothly under mild reaction conditions. With this developed protocol, sorts of polycyclic compounds with chroman motifs were obtained in high level of yields and moderate to excellent diastereoselectivities (up to >99% yield, >20:1 dr). (C) 2019 Elsevier Ltd. All rights reserved.