N-(arylsulphonyl)tetrahydropyridinium salts: intermediates for multi-ring heterocycles. Part 1. Synthesis of hexahydropyrido[1,2-b][1,2,4]benzothiadiazine dioxides

Abstract

N-(Arylsulphonyl)tetrahydropyridinium salts were obtained regiospecifically and in high yield by smooth triflate-assisted decarbonylation of the corresponding N-(arylsulphonyl)piperidine-2-carboxylic acid chlorides at room temperature. These synthons were converted into the nitroamines, which reductively cyclocondensed to give the new 9-substituted tricyclic azacycles, hexahydropyrido[1,2-b][1,2,4]benzothiadiazine 6,6-dioxides.