Reissert indole synthesis

The Reissert indole synthesis is a series of chemical reactions designed to synthesize indole or substituted-indoles (4 and 5) from ortho-nitrotoluene 1 and diethyl oxalate 2.

[3] The first step of the synthesis is the condensation of o-nitrotoluene 1 with a diethyl oxalate 2 to give ethyl o-nitrophenylpyruvate 3.

If desired, 4 can be decarboxylated with heat to give indole 5.

In an intramolecular version of the Reissert reaction, a furan ring-opening provides the carbonyl necessary for cyclization to form an indole.

A ketone side chain is present in the final product, allowing further modifications.