A general and efficient method for the synthesis of 2, 3-unsubstituted indoles has been established by the intramolecular cyclization of N-benzyl 2-anilinoacetals. Acidic mesoporous molecular sieve (MCM-41-SO3H) has shown excellent catalytic activity on this transformation, and the 2, 3-unsubstituted indoles bearing 7-substituent or strong electron- withdrawing substituents also could be achieved by this protocol. Moreover, the ...
