Simple Synthesis of Some 2-Substituted Melatonin Derivatives

A simple strategy for the synthesis of some 2-substituted melatonin derivatives using p-anisidine as starting material is reported. The key step is a chemoselective reduction of a cyano group in the presence of an appropriate acid anhydride by hydrogenation over Adams' catalyst or with sodium borohydride in the presence of catalytic amounts of anhydrous nickel(II) chloride. The 2-substituted melatonin derivatives were obtained in six or seven steps from inexpensive p-anisidine in 9-13% overall yield.