Direct Amidation of Carboxylic Acids Catalyzed by ortho-Iodo Arylboronic Acids: Catalyst Optimization, Scope, and Preliminary Mechanistic Study Supporting a Peculiar Halogen Acceleration Effect
Nicolas Gernigon, Raed M. Al-Zoubi and Dennis G. Hall*
*Department of Chemistry, University of Alberta, Gunning-Lemieux Chemistry Centre, 4-010 Centennial Centre for Interdisciplinary Science, Edmonton, Alberta, T6G 2G2, Canada, Email: dennis.hallualberta.ca
N. Gernigon, R. M. Al-Zoubi, D. G. Hall, J. Org. Chem., 2012, 77, 8386-8400.
DOI: 10.1021/jo3013258 (free Supporting Information)
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5-methoxy-2-iodophenylboronic acid (MIBA) is kinetically very active in a catalytic, direct amidation employing free carboxylic acids and amines providing high yields of amide products in short reaction times under mild conditions at ambient temperature in the presence of molecular sieves. A possible catalytic cycle is based on the presumed formation of an acylborate intermediate.
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