The subject matter of this thesis is concerned with investigations of novel heterocyclisation reactions of isocyanide dihalide derivatives. The description of the results obtained in these studies is preceded in chapter 1 by a survey of known reactions of such compounds and their synthesis. Chapter 2 describes investigations into the synthesis of dihaloisocyanodiphenylamine derivatives and their subsequent Lewis acid catalysed reactions to dibenzo[b,f]-2,4-diazepine derivatives. Chapter 3 describes the synthesis of various isocyanide dihalides, all of which had the potential to undergo Lewis acid catalysed cyclisation to polycyclic heteropine and heterocine derivatives including benzonaphthoxazepines, pyridonaphthoxazepines and dibenzoxacozines.