Issue 21, 2018

Lewis acid catalyst-steered divergent synthesis of functionalized vicinal amino alcohols and pyrroles from tertiary enamides

Abstract

We report herein two Lewis acid catalyst-steered distinct reaction pathways of N-formylmethyl tertiary enamides. In the presence of a catalytic amount of AlCl3 and 4 Å molecular sieves, the stable N-formylmethyl tertiary enamides underwent sequential reactions involving intramolecular nucleophilic addition of tertiary enamides to aldehydes, isomerization and dehydration aromatization to produce diversely polysubstituted pyrroles in excellent yields. However, the Sc(OTf)3-catalyzed reaction of the same tertiary enamides proceeded through, after the initial enaminic addition to aldehydes, hydration of the cyclic iminium intermediates and the ring opening reaction to furnish functionalized vicinal amino alcohol derivatives in 40%–84% yields. The synthetic utility of the method was further demonstrated by the gram-scale preparation of di- and tri-substituted pyrroles and 1-acetyl-4,5,6,7-tetrahydro-1H-indole, and by a facile transformation of a functionalized pyrrole into 5H-pyrrolo[2,1-a]isoindol-5-one.

Graphical abstract: Lewis acid catalyst-steered divergent synthesis of functionalized vicinal amino alcohols and pyrroles from tertiary enamides

Supplementary files

Article information

Article type
Research Article
Submitted
08 Aug 2018
Accepted
21 Sep 2018
First published
25 Sep 2018

Org. Chem. Front., 2018,5, 3138-3142

Lewis acid catalyst-steered divergent synthesis of functionalized vicinal amino alcohols and pyrroles from tertiary enamides

X. Xu, C. Lei, S. Tong, J. Zhu and M. Wang, Org. Chem. Front., 2018, 5, 3138 DOI: 10.1039/C8QO00839F

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