Highly Chemoselective Esterification from O-Aminoallylation of Carboxylic Acids: Metal- and Reagent-Free Hydrocarboxylation of Allenamides |
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| Authors: | Dr Tapas R Pradhan Hae Eun Lee Gisela A Gonzalez-Montiel Prof Paul Ha-Yeon Cheong Prof Jin Kyoon Park |
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| Institution: | 1. Department of Chemistry and Institution for Functional Materials, Pusan National University, Busan, 46241 Korea;2. Department of Chemistry and Institution for Functional Materials, Pusan National University, Busan, 46241 Korea
These authors contributed equally.;3. Department of Chemistry, Oregon State University, Corvallis, OR, 97331 USA |
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| Abstract: | Metal-free hydrocarboxylation of allenamides with various functionalized carboxylic acids were achieved with complete regio- and stereocontrol (>49:1). This environmentally compatible transformation affords γ-acyloxyenamides with exclusive E-selectivity. Electron rich, electron poor, aliphatic, aryl, and heterocyclic carboxylic acids all gave excellent yields (avg. 89 %, 47 examples). We demonstrate the synthetic potential of this transformation in the late-stage modification of complex natural carboxylic acids and simple modification of the products to three-carbon synthons with ample opportunity for further diversification. DFT studies revealed that the reaction occurs in a stepwise manner through the intermediacy of a conjugated iminum species, which is rapidly captured by the carboxylate ion, resulting in the observed linear selectivity. |
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| Keywords: | Brønsted acid carboxylic acids (E)-enamides linear selective metal-free |
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