Exploring New Methods of Aza-oxyallyl cation Generation

Abstract

Considering that carbon-nitrogen bond formation is frequently required at various stages in the synthesis of pharmaceuticals and materials, developing efficient new methods of C-N bond formation is a worthwhile endeavor. The (4+3)-cycloaddition through a new reaction intermediate, known as the aza-oxyallyl cation, has recently been established as a premiere method of synthesizing seven-membered heterocycles containing nitrogen. The goal of this study was to expand the scope of this novel reactivity by exploring the possibility of Lewis acid-catalyzed aza-oxyallyl cation generation from hydroxamate chalcone epoxides and imidates in the presence of electronrich arenes. Hydroxamate chalcone epoxides were found to undergo electrophilic aromatic substitution at the ?-position, indicating that an aza-oxyallyl cation is not in fact generated under these conditions. Imidates were found to undergo two electrophilic aromatic substitution reactions to yield doubly substituted furan products. These initial results are a promising indication that aza-oxallyl cations can indeed be generated under Lewis-acid mediated conditions.