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Thiourea-catalyzed dearomatizing [4+2] cycloadditions of 3-nitroindole

Paper ID Volume ID Publish Year Pages File Format Full-Text
50355 46792 2015 6 PDF Available
Title
Thiourea-catalyzed dearomatizing [4+2] cycloadditions of 3-nitroindole
Abstract

•Nitroindoles are dearomatized at r.t. to generate elaborated polycyclic compounds.•Thiourea catalyze the dearomatization of 3-nitroindoles by [4+2] cycloadditions.•Thiourea catalyze the dearomatization of 3-nitroindoles by [4+2] / [3+2] cycloaddition.

We have developed two efficient thiourea promoted dearomatizing processes involving the cycloadditions of 3-nitroindoles. The C2C3 double bond of the heteroarene can be involved as electron-poor 2π dienophile in [4+2] cycloadditions. While the uncatalyzed process requires harsh conditions, the organocatalyzed reaction takes place at room temperature and atmospheric pressure. The C2C3NO motif of the heteroarene can also react as an electron-poor 4π heterodiene in [4+2] / [3+2] cycloadditions cascades, under high pressure. In contrast to Lewis acid activation, thiourea promotion thus proves efficient even under unconventional activation conditions and in the presence of acid sensitive reactants such as enol ethers.

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Keywords
Dearomatization; Cycloaddition; Thiourea; Organocatalysis; Nitroindole
First Page Preview
Thiourea-catalyzed dearomatizing [4+2] cycloadditions of 3-nitroindole
Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 63, 10 March 2015, Pages 15–20
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis