A study of the thermally-induced cyclisations of some polyfluoroaromatic hydrazones leading to Fischer indole products

Abstract

Previously acetophenone 1,3,4,5,6,7,8-heptafluoro-2-naphthylhydrazone and acetophenone pentafluorophenylhydrazone were reported to react in tetralin at reflux temperature to give among the products 4,5,6,7,8,9- hexafluoro-2-phenylbenz[ e ]indole and 4,5,6,7-tetrafluoro-2-phenylindole respectively. These are typical Fischer indole products, and yet are formed by the surprising loss of ortho-fluorine rather than orthohydrogen. The work contained in this thesis is concerned with exploring the generality of this reaction: polyfluoroaromatic hydrazones with a variety of substituents have been synthesized, and their response to cyclization investigated. The thesis is divided into three main sections. Chapters one, two, three, and four deals with the literature on the synthesis of partially fluorinated heterocyclic compounds. Chapter five discusses the synthesis of some new partially fluorinated indoles, whilst chapter six contains the experimental detail for this work.