[1,5] HYDROGEN SHIFT IN AZA-ORTHO-XYLYLENES GENERATED FROM 3-ALKYL-2,1-BENZISOTHIAZOLINE 2,2-DIOXIDES

Aza-ortho-xylylenes generated by the thermal extrusion of SO2 from 3-alkyl-2,1-benzisothiazoline 2,2-dioxides 4 undergo [1,5] hydrogen shift leading to 2-aminostyrene derivatives 6. In the case of 1,3-diallylbenzosultam 7 such transformation leads to N-allylaminophenyl-1,3-butadiene 9 which cyclizes to 5,6,6a,7,8,10a-hexahydrophenanthridine 10. Cyclobutanospiro-3-benzosultams 11 after the extrusion of SO2 and the [1,51 hydrogen shift form unstable phenylcyclobutenes, which undergo electrocyclic ring opening to 2-phenyl-1,3-butadienes 14. 3-Chloromethyl-3-methylbenzosultams 17 transform into 1,3-dimethylindole derivatives 21.