Synthesis of fused and bridged bicyclic diazenium salts by intramolecular cycloaddition.

Bicyclic diazenium salts were efficiently prepared by a Lewis acid mediated intramolecular cycloaddition. Terminal olefins provided mixtures of fused and bridged bicyclic diazenium salts. The alpha-chloroazo cycloaddition precursors were conveniently prepared from the corresponding phenyl hydrazones by treatment with chlorodimethylsulfonium chloride.