Synthesis of indoles via alkylidenation of acyl hydrazides

Hisler, K. and Commeureuc, A.G.J. and Zhou, S.Z. and Murphy, J.A., EPSRC (Funder), WestCHEM (Funder) (2009) Synthesis of indoles via alkylidenation of acyl hydrazides. Tetrahedron Letters, 50 (26). pp. 3290-3293. ISSN 0040-4039 (

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Indoles have been synthesised via alkylidenation of acyl phenylhydrazides using phosphoranes and the Petasis reagent, followed by in situ thermal rearrangement of the product enehydrazines. The Petasis reagent provides an essentially neutral equivalent of the [acid-catalysed] Fischer indole synthesis, but with acyl phenylhydrazides as starting substrates. Alkylidene triphenylphosphoranes convert aroyl phenylhydrazides to indoles, but acyl phenylhydrazides derived from aliphatic carboxylic acids undergo a Brunner reaction to form indolin-2-ones.