Base-controlled [3+3] cycloaddition of isoquinoline N-oxides with azaoxyallyl cations

Abstract

A base-controlled [3+3] cycloaddition reaction of isoquinoline N-oxides with azaoxyallyl cations is developed. 1,11b-dihydro-[1,2,4]oxadiazino[3,2-a]isoquinolin-2(3H)-ones are obtained when isoquinoline N-oxides are treated with α-halohydroxamates in the presence of sodium carbonate, while 2-(isoquinolin-1-yloxy)acetamides are unexpectedly produced when the base is changed to cesium carbonate. This transformation proceeds through an azaoxyallyl cation generated in situ from α-bromohydroxamate, and the [3+3] cycloaddition reaction is the key step for the final outcome.