The dipolar cycloaddition reaction is a powerful and widely used strategy as it ensure 100% atom economy with a single operation. This process is most frequently used to construct of five- and six-membered ring system. Azomethine ylides represent an important class of dipole and are synthons for the synthesis of N-heterocycles that potentially have biological activities. Among various approaches for the generation of azomethine ylide, metal-catalyzed decomposition of a-diazo carbonyl compounds, and subsequent carbene addition and cycloaddition has been one of the most popular and effective approaches. In this seminar, new azomethine ylides, prepared from rhodium(II)-azavinyl carbene, will be present.
The proximity and conformational constraints between dipoles and dipolarophiles often lead to regio- or stereoselectivity. We developed the stereoselective synthetic method of enamides using benzamides behaved as a well matched dipolarophile to participate in cyclization with rhodium(II)-azavinyl carbene. Next, we will discuss an air-stable azomethine ylides with an unusual pattern of charge distribution prepared from the rhodium(II)-catalyzed reaction between pyridines and 1-sulfonyl-1,2,3-triazoles. This reaction allowed for the first example of the catalytic multicomponent [5 + 2] cycloaddition reactions, thus resulting in the formation of biologically active 1,4-diazepine compounds. We also introduce the higher order cycloaddition reactions using developed azomethine ylides in brief.