156141-41-2Relevant academic research and scientific papers
Intramolecular addition of acyldiazenecarboxylates onto double bonds in the synthesis of heterocycles
Prata, Jose V.,Clemente, Dina-Telma S.,Prabhakar, Sundaresan,Lobo, Ana M.,Mourato, Isabel,Branco, Paula S.
, p. 513 - 528 (2007/10/03)
Appropriate aryl-substituted unsymmetrical azodicarbonyl compounds, generated from bishydrazides by oxidation, undergo intramolecular cyclisations to furnish a variety of useful heterocycles such as N-substituted oxindoles, carbostyrils, benzazepinones, benzazocinones, benzimidazolones, benzoxazinones and pyrazolones in varying degrees of efficiency. Methods are described to remove the N-acyl groups from the heteroaromatic compounds. Under mildly acidic conditions where equal opportunities are available for an ipso or a normal cyclisation it is the former process that occurs preferentially. Evidence is presented in favour of a C-to-C migration in the ipso product for the formation of a methoxy-substituted carbostyril derivative. One of the spiro substances is shown to participate in dienone-phenol rearrangement to provide the corresponding quinolone-phenol in high yield.
