Conversions of primary amino groups into other functionality mediated by pyrylium cations

Primary amines react with pyrylium cations to give pyridiniums which transfer the N-substituent to a wide range of halide, O-, S-, N-, C- and H-nucleophiles and undergo elimination and rearrangement reactions. Kinetic study of the formation and displacement steps has enabled the selection of substituents on the original pyrylium to optimise conditions for both steps. The procedure represents a widely applicable two-step sequence for the selective conversion of primary amino groups into many other functionalities under mild conditions in high yields.