Five-membered ring carbenes: electronic, steric properties and catalytic hydrophosphination of alkynes

Abstract

Five-membered ring carbene is a characteristic category of carbene, which was found to be possible to act as reagent on its own and therefore has been utilized in various types of reactions. Although there have been numerous fundamental studies on carbenes, they are mostly limited to carbenes acting as ligands. Here, the electronic and steric properties of five-membered ring carbenes were analyzed, and the mechanistic study on catalyzed hydrophosphination of alkynes was conducted via density functional theory-aided computational methods. The mechanistic study on catalyzed hydrophosphination of alkynes revealed that the product selectivity depends on the relative energies of three states, and the existence of the heteroatom in the alkyne substrate is likely to change the reaction mechanism. This research will offer more insights about various five-membered ring carbenes and their role other than acting as ligands, and unveiling the aforementioned reaction mechanism will be helpful for the development of other useful methodologies with five-membered carbenes.