| Scope and method of study. Research.;Findings and conclusions. An efficient route to synthesize various heterocycles has been developed based on tandem reactions initiated by a dissolving metal reduction. New methods have been developed which involves either the use of a tandem reduction-reductive amination, reduction-cyclization or a reduction-lactamization sequence to achieve potentially valuable target molecules. The key steps involved in the procedure are (i) reduction of an aromatic nitro group using iron in presence of an acid followed by (ii) intramolecular cyclization with either an aldehyde, ketone, ester or alpha,beta-unsaturated ketone. Different heterocycles such as carbazoles, pyridoindolones, spiro-fused 3,4-dihydro-2(1H)-quinolinone derivative, two tricyclic linear fused rings system, aryl and alkyl dihydro-4(1H)-quinazolinones, 4(1H)-quinolinones and dihydroquinolinones were successfully synthesized by this method. The use of these mild procedures allows reasonable structural variation and avoids the use of hazardous reagents or expensive catalysts. Some of the heterocyclic targets prepared by this method are currently used as drugs or are precursors to drugs in advanced clinical studies.;A commercial route for the synthesis of SHetA2 heteroarotinoid ring was developed. Syntheses of metabolites of SHetA2 were developed using a 17-step synthetic route. |
