REACTIONS OF AZA-ORTHO-XYLYLENES GENERATED FROM 2,1-BENZISOTHIAZOLINE 2,2-DIOXIDES

Thermal extrusion of SO2 from 2,1-benzisothiazoline 2,2-dioxides 2 leads to aza-ortho-xylylenes 3, which depending on the substituents undergo various transformations. Aza-ortho-xylylenes substituted at the position 4, 5, and 6 gave Diels-Alder reactions with maleic acid derivatives 4 leading to cis-1,2,3,4-tetrahydroquinoline 2,3-dicarboxylic acid derivatives 5 in high yields. 7-Substituted derivatives underwent [1,5] hydrogen shift leading to ortho-toluidine derivatives 9 and 10. Aza-ortho-xylylenes generated from N-(4-pentenyl) and N-(5-hexenyl) derivatives 11 gave products of intramolecular Diels-Alder reaction.