Tandem cyclization–cycloaddition reactions of rhodium generated carbenoids from α-diazo carbonyl compounds

Abstract

The rapid generation of molecular complexity, in a controlled and predictable manner, is a contemporary theme in the practice of modern organic synthesis and finds application in accessing newer entities for the pharmaceutical industry. Efficiency, atom economy, regio-, stereo- and enantiocontrol, ready availability of starting materials and environmentally benign processing are some of the common concerns in any synthetic endeavor. Synthetic brevity is, however, central to the generation of molecular complexity in a resource-effective manner and, in order to attain that objective, two strategic options have been generally explored in recent years, one involving multicomponent reactions and the other involving reactions leading to multiple carbon-carbon bond formation through tandem processes. The latter approach involves recourse to reactions like multiple cycloadditions or cyclization–cycloaddition sequences in which many bonds are formed in a single mode operation and these cascade processes have an inherent advantage in expeditiously assembling polycyclic structures with proper stereochemical control.