Catalyst-Free Synthesis of Aminals from Indole-Derived α,α-Di­cyanoolefins

We have developed an efficient synthesis of indole fused aminals with nucleophilic imines and indole-derived α,α-dicyanoolefins via N -sulfonyl group transfer. The combination of two privileged frameworks, tetrahydroisoquinoline or tetrahydro-β-carboline and indole, can be realized by this approach to the construction of aminals. The synthetic application of this method was further demonstrated by the straightforward transformations into highly functionalized aminals possessing carbonyl groups through oxidative cleavage of the nitrile moiety.