Direct Synthesis of Amides from Carboxylic Acids and Amines Using B(OCH2CF3)3
Rachel M. Lanigan, Pavel Starkov and Tom D. Sheppard*
*Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon St, London, WC1H 0AJ, U.K., Email: tom.shepparducl.ac.uk
R. M. Lanigan, P. Starkov, T. D. Sheppard, J. Org. Chem., 2013, 78, 4512-4523.
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The commercially available B(OCH2CF3)3 is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, products can be purified by a simple filtration using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization.
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In general the reaction temperature was found to be more important than the time. Reactions carried out during our initial studies were run for 15 h, but most of the examples subsequently explored went to completion within the shorter reaction time of 5 h.
Tom D. Sheppard, June 6, 2014