Construction of Chiral Tricyclic Indoles through a Rhodium-Catalyzed Asymmetric Arylation Protocol.

A rhodium/diene complex catalyzed asymmetric 1,4-addition of arylboronic acids to indole-derived α,β-unsaturated esters to access highly enantioenriched 3-(1H-indol-2-yl)-3-arylpropanoates has been developed. By taking advantage of the nucleophilic character of indole at C3 and N1 positions, construction of a series of valuable chiral tricyclic indole frameworks such as 2,3-dihydro-1H-pyrrolo[1,2-a]indoles and cyclopenta[b]indoles can be efficiently achieved.