Generation and reactions of heteroanalogues of aza-ortho-xylylenes

Article abstract of DOI:10.1016/S0040-4039(97)00962-3

Intramolecular nucleophilic substitution of chlorine in 2-chloro-3-(alkanesulfonylamino)pyridines furnishes N-alkyl-1,3-dihydroisothiazolo[4,3-b]pyridine 2,2-dioxides (pyridosultams, 8), which undergo thermal extrusion of SO₂ giving heteroanalogues of aza-ortho-xylylenes 9. These reactive 1-azadienes enter [4+2] cycloaddition with dienophiles leading to tetrahydro[1,5]naphthyridines 11. With an excess of dienophile (N-phenylmaleimide) pyridoazocine derivatives 12 and 13 being 2:1 adducts are formed.