Substituted 3-<i>E-</i>Styryl-2<i>H</i>-chromenes and 3-<i>E-</i>Styryl-2<i>H</i>-thiochromenes: Synthesis, Photophysical Studies, Anticancer Activity, and Exploration to Tricyclic Benzopyran Skeleton
of densely substituted 2H-chromenes and 2H-thiochromenes were synthesized in good yield through cyanuric chloride-dimethylformamide mediated cleavage of different spiro-4-hydroxychroman-3,1′-cyclopropanes and similar thiochroman analogues. This protocol involves operationally very simple, facile and cost-effective reactions using easily accessible reagents under mild reaction condition with tolerance