A Metal-Free Reductive N-Alkylation of Indoles with Aldehydes.

A simple metal-free method has been developed for the reductive N-alkylation of indoles employing aldehydes as the alkylating agent and inexpensive Et3SiH as the reductant. A wide range of aromatic and aliphatic aldehydes are viable substrates along with a variety of substituted indoles. In addition, the method was applied to a one-pot sequential 1,3-alkylation of a substituted indole and successfully demonstrated on a 100 mmol scale.