Influence of Sulfur on Acid-Mediated Enamide Formation

Sep 11, 2017 - mide side chains, to the corresponding Z-isomers using. Scheme 2. (A) Proposed Mechanism for (Thio)enamide. Formation and (B) Variation...
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Letter pubs.acs.org/OrgLett

Influence of Sulfur on Acid-Mediated Enamide Formation Joshua A. Lutz, Visal Subasinghege Don, Revati Kumar, and Carol M. Taylor* Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States S Supporting Information *

ABSTRACT: The acid-mediated condensation of acetamide with butanal dimethylacetal and EtSCH2CH(OMe)2, followed by dehydration, was investigated by electronic structure calculations that supported the prediction that the Z-geometry would be favored in the product. The reaction was investigated experimentally using suitably functionalized cysteine building blocks. Some side reactions and optimization of reaction conditions are reported, en route to identifying a mild, inexpensive Lewis acid that achieves a reasonable yield of (Z)-thioenamide 21 with high stereoselectivity.

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