Three-component domino reactions for selective formation of indeno[1,2-b]indole derivatives.

Efficient three-component domino strategies for the synthesis of multifunctionalized tetracyclic indeno[1,2-b]indole derivatives with different substituted patterns have been established successfully. The first pathway involves a novel sequential methyl migration, aromatization, and esterification, while a second reaction in HOAc leads to compounds 6 with high syn diastereoselectivity. Both reactions showed attractive features including mild conditions, convenient one-pot operation, short reaction times of 15-32 min, and excellent regio- and/or stereoselectivity.