Stereodivergent Synthesis of Trisubstituted Enamides: Direct Access to Both Pure Geometrical Isomers

Luca Massaro; Jianping Yang; Suppachai Krajangsri; Emanuele Silvi; Thishana Singh; Pher G Andersson

doi:10.1021/acs.joc.9b01803

Stereodivergent Synthesis of Trisubstituted Enamides: Direct Access to Both Pure Geometrical Isomers

J Org Chem. 2019 Nov 1;84(21):13540-13548. doi: 10.1021/acs.joc.9b01803. Epub 2019 Oct 9.

Authors

Luca Massaro¹, Jianping Yang¹, Suppachai Krajangsri¹, Emanuele Silvi¹, Thishana Singh², Pher G Andersson^{1

2}

Affiliations

¹ Department of Organic Chemistry , Stockholm University, Arrhenius Laboratory , 10691 Stockholm , Sweden.
² School of Chemistry and Physics , University of Kwazulu-Natal , Private Bag X54001 , Durban 4000 , South Africa.

PMID: 31532658
DOI: 10.1021/acs.joc.9b01803

Abstract

A stereodivergent strategy has been developed to access either (E)- or (Z)-isomers of trisubstituted enamides. Starting from an extensive range of ketones, it was possible to synthesize and isolate the desired pure isomer by switching the reaction conditions. Lewis acid activation enables the formation of the (E)-isomers in high stereoselectivity (>90:10) and good yields. On the other hand, the use of a Brønsted acid allows the preparation of the (Z)-isomers, again in high selectivity (up to 99:1), with moderate yields.