Manganese(III)-mediated reactions of vinyl azides and 1,3-dicarbonyl compounds or cyclopropanols : synthesis of azaheterocycles

Abstract

In this thesis, the author describes efficient methods to synthesize azaheterocycles by using readily accessible vinyl azides as fundamental substrates. These methods involve iminyl radicals as key intermediates, which are generated by the addition of α- or β-carbonyl radicals to the C═C bond of vinyl azides with the elimination of dinitrogen. The α- and β-carbonyl radicals are generated by the oxidation of 1,3-dicarbonyl compounds and cyclopropanols with Mn(III) complexes, respectively. The construction of azaheterocyclic frameworks is achieved by the cyclization of iminyl radicals onto an intramolecular carbonyl group. Importantly, the radical chain reactions are then terminated by the reduction of alkoxy radicals by the resulting Mn(II) species to afford Mn(III)alkoxides, from which azaheterocyclic products are formed with regeneration of active Mn(III) species. Therefore, this characteristic oxidative initiation and reductive termination process promotes these reactions in a catalytic manner.