Three-Component Domino Reactions for Regioselective Formation of Bis-indole Derivatives

A microwave-assisted regioselective reaction dealing
with arylglyoxal
monohydrate, diverse N-aryl enaminones, and indoles
to achieve 3,2′- and 3,3′-bis-indoles by varying a substituted
indole substrate is reported. The 2-unsubstituted indoles resulted
in the 3,2′-bis-indole skeleton, whereas indoles bearing a
methyl or phenyl group at C2 led to the 3,3′-bis-indoles with
simultaneous formation of three sigma-bonds. The procedures feature
excellent regioselectivity, short reaction times, convenient one-pot
manner, and operational simplicity.