Reactivity of 4-azido- and 4-amino-6-methyl-2H-pyran-2-one. Preparation of 1-(6-methyl-2-oxopyran-4-yl)-1,2,3-triazoles and 5-oxopyrano[4,3-b]pyridines

1,3-Dipolar cycloadditions of stable 4-azido-6-methyl-2H-pyran-2-one 1 with electron-rich alkenes and alkynes lead to 4,5-substituted 1-(6-methyl-2-oxopyran-4-yl)-1,2,3-triazoles. Iminophosphoranes derived from 1 have also been synthesized. 5-Oxopyrano[4,3-b]pyridines are prepared by reaction of 4-amino-6-methyl-2H-pyran-2-one 2 with β-dicarbonyl compounds.