Synthesis of substituted N-heterocycles via a cascade of Michael addition, double cyclization and air oxidation

Abstract

An efficient synthesis of α-carbolinones (pyridoindolones) and α-carbolines (pyridoindoles) from 2-(2-aminophenyl)acetonitriles and alkyl/arylidene malonates and 2-benzylidene-3-oxopentanoates mediated by Cs₂CO₃ in excellent yields has been developed. This methodology enables the formation of five- and six-membered nitrogen heterocyclic compounds via Michael addition, followed by double cyclization, elimination, rearrangement and air oxidation in a cascade fashion. Post-synthetic modification enables the synthesis of pentacyclic nitrogen heterocyclic compounds.