FeCl3-catalyzed efficient synthesis of di(5-methylfuran/thiophen-2-yl)isatin analogues

A simple, inexpensive, environmentally friendly, and high yield protocol is described for the synthesis of (5-methylfuran/thiophene-2-yl)isatin by the reaction of 2-methylfuran/2-methylthiophene with isatin/isatin imine in the presence of FeCl3. The present protocol is ideal for the direct introduction of 2-methylfuran/2-methylthiophene onto isatin at 3-position with complete regioselectivity.