Nucleophilic ortho allylation of heteroaryl sulfoxides

Abstract

The Pummerer reaction, first described in 1909 by Rudolf Pummerer, has become over time a useful and versatile tool for synthetic chemists. An application of the Pummerer reaction explored by the group is the ortho allylation of aromatic rings through the reaction of allylic carbon nucleophiles on aryl and heteroaryl sulfoxides.Aryl and heteroaryl sulfoxides undergo ortho allylation upon activation with Tf2O or TFAA and treatment with allylsilanes. Work previously done by the group involves the allylation of a range of substrates, including some heteroaryl sulfoxides, in moderate to high yields.The objective of my work is to extend the use of the Pummerer-type ortho allylation to a number of new heteroarylic substrates and thus study the effect of different protecting groups, either electron-donating or electron-withdrawing, test the reactivity of different heteroaromatic rings, to optimize the conditions under which the reaction is carried out and to explore the possibility of further product manipulation.Positive results have been obtained for the allylation of six heteroaromatic sulfoxide substrates, suggesting that the Pummerer allylation could be a useful process for other heterocyclic systems. It is clear that the choice of protecting group for nitrogen is important in N-heterocycles. In one case introducing an allyl group onto an N-allyl-protected substrate led to the synthesis of a new heterocyclic species by RCM.

Date of Award	31 Dec 2012
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Procter (Supervisor)