Diazo compounds being used as a precursor of carbenes in synthetic chemistry by reacting them in different manners like photochemically, thermally or with metal catalysts. Further, the use of metals as a catalyst generates metallocarbenes in the reaction medium which has similar reactivity like free carbenes. In this context, a number of transition metal catalysts like Rh, Pd, Cu, Ru, Ir, Fe etc. have been employed to generate metal bound carbenes in the reaction medium. Among various metal catalyst, rhodium being used extensively in industry as well as in academia to catalyze a number of cascade transformations containing carbene insertion/transfer. In this review, we are covering the efforts made in the last five years toward the synthesis of highly important heterocyclic compounds such as isoquinoline, indoles, isocoumines, oxazoles, carbazoles etc. through rhodium catalysed cascade reactions containing carbene transfer as the vital step.

A Pd-catalyzed one-pot cascade consisting C-C/C-O/N-N bond formation to access clinically important fused 1,2,3-triazole using N-aryl-α-(tosyl hydrazone)acetamides with isocyanide has been developed. Besides, various substitutions on N-aryl part of acetamides...

Herein, a divergent and selective synthesis of (E)-3alkylidene oxindole, which is a highly valuable framework due to its presence in biologically important molecules, via palladiumcatalyzed multicomponent reaction of 3-diazo oxindole, isocyanide, and aniline has been developed. Further, the feasibility of the reaction was demonstrated by employing differently substituted 3diazo oxindoles, isocyanides, and anilines as starting material and obtaining the corresponding products in 31−83% isolated yields. Besides, a plausible mechanism has been presented and further investigated using DFT calculations which suggest the formation of the Pd-carbene complex and ketenimine intermediate as the key step during the catalytic cycle.