Novel one-pot multi-bond forming reaction processes for the preparation of biologically active heterocycles

During the course of this PhD, a new one-pot thermal Overman rearrangement and ring-closing metathesis process was developed for the preparation of polycyclic compounds. In this method, commercially available phenols and anilines were converted to alkene derived allylic alcohols and then transformed via a one-pot process into 5-amino 2,5-dihydro-1-benzoxepines and 5-amino 2,5-dihydro-1H-benzazepines. The synthetic utility of these compounds was explored with the preparation of highly substituted hydroxylated analogues as well as a highly active hypotensive agent. A novel one-pot process was also developed for the synthesis of allylic amide derived 2H-chromenes. The key substrates, propargyloxy cinnamyl alcohols were rapidly prepared from readily available salicylaldehydes. One-pot thermal Overman rearrangement of the corresponding allylic trichloroacetimidates, followed by a gold(I)-catalysed hydroarylation gave the 2H-chromenes in high yields. A mild chemoselective method for the oxidation of the 2H-chromenes to give coumarins was also discovered