In certain countries, many of the reagents used to transform carboxylic acids to acyl halides such as phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride, phosphoryl chloride, thionyl chloride and sulfuryl chloride are difficult to come by. Against this background, the authors developed the reaction system triphenylphosphine (PPh3) – bromotrichloromethane (BrCCl3) to prepare acyl halides in situ. In the following, the use of this reagent combination is joined with the reaction of the in situ prepared acyl halides with nitrogen nucleophiles, specifically with hydrazines, methylamine and anilines. The reaction is also used in an intramolecular variant by the reaction of maleanilic acids to N-arylmaleimides.
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Use of PPh3-BrCCl3 in the preparation of acylhydrazines, N-methylamides, anilides and N-arylmaleimides from carboxylic acids
Published: 14 November 2019 by MDPI in The 23rd International Electronic Conference on Synthetic Organic Chemistry session General Organic Synthesis
Keywords: Appel-type reaction; N-arylmaleimides, acylhydrazines