Formation of N-alkoxyindole framework: intramolecular heterocyclization of 3-alkoxyimino-2-arylalkylnitriles mediated by ferric chloride.

A variety of functionalized N-alkoxyindole-3-carbonitrile derivatives are achieved under remarkably mild conditions by applying a FeCl3-mediated intramolecular heterocyclization of 3-alkoxyimino-2-arylalkylnitriles. This novel synthesis allows the N-moiety on the side chain to be annulated to the benzene ring as the final synthetic step, which enables the functionalization of the benzenoid portion of the indole at an early stage of the synthesis.