Synthesis of Isothiochromenes and 1,3-Dihydrobenzo[c]thiophenes by Iodine- and Hydrobromic Acid-Mediated Cyclizations of o-[(tert-Butylsulfanyl)methyl)]styrenes

Methods for the syntheses of 4-substituted isothiochromenes and 1,1-disubstituted 1,3-dihydrobenzo[c]thiophenes have been developed.Thus, treatment of α-substituted o-[(tert-butylsulfanyl)methyl]styrenes, derived from α-substituted o-bromostyrenes using an easily operated four-step sequence, with iodine in the presence of sodium hydrogencarbonate gave isothiochromene derivatives.These tert-butyl sulfides were treated with concentrated hydrobromic acid to give 1,3-dihydrobenzo[c]thiophene derivatives.