[3+3] Cycloaddition of Azomethine Imine: Synthesis of Bi- or Tricyclic N-Heterocycle

Synthesis of six-membered bicyclic, tricyclic or tetracyclic N-heterocycles are important due to enormous use of such scaffolds in bioactive natural products, agrochemicals and in pharmaceuticals. [3+3] cycloaddition of azomethine imine for the construction of such heterocycles is less explored but also a genuine approach with the other method like [4+2] and [2+2+2] cycloaddition. Hence, the literature survey in this area is utmost significant. The delights and difficulties of [3+3] cycloaddition of azomethine imine have been deliberated thoroughly to elucidate this highly mounting field in this literature study. Herein, we report a vast synthetic method [base catalyzed, metal catalyzed (racemic and asymmetric), phosphine catalyzed, NHC and Lewis acid catalyzed] for the synthesis of di, tri and tetra-nitrogen containing heterocycles via [3+3] cycloadditon reaction of azomethine imine.