Theoretical study of the mechanism of thieno[3,2-b]benzofuran bromination

The bromination reaction of thieno[3,2-b]benzofuran was studied theoretically. Stationary points on the reaction potential energy profile including intermediates and transition states were successfully located employing hybrid DFT procedure at the B3LYP/6-31G* level of theory. The bromination proceeds in two steps at the C(2) carbon of thiophene ring. Initially, a p-complex forms between bromine molecule and thiophene ring. Further the p-complex with high activation barrier 69.9 kcal/mol transforms to s- complex intermediate. Finally the s-complex with 4.6 kcal/mol activation transforms to product 2-bromothieno[3,2-b]benzofuran.