Reactions of some 2H-chromenes and 2H-thiochromenes with triazolinediones

Article abstract of DOI:10.1016/0040-4020(95)00874-8

Simple 2H-chromenes and 2H-thiochromenes form the [2+2]-adducts, tetrahydrol[1]benzo(thio)pyrano[3,4-c][1,2]diazeto[1,2-a][1,2,4]-triaz oles, with triazolinediones, whereas their 3- and 4-bromo and the corresponding cycloalkylamino derivatives undergo an overall electrophilic substitution sequence.