Decarbonylative Issues Involved in Ru(II)-catalyzed [6+2-1] Annulation Reaction of Hydroxychromone with Alkyne: A DFT Study

Density functional theory calculations have been performed to explore the Ru-catalyzed decarbonylative annulation reaction of 3-hydroxy-2-phenyl-chromone with an alkyne to synthesize spiroindenebenzofuranones. A Ru(II)-Ru(0)-Ru(II) rather than a Ru(II)-Ru(IV)-Ru(II) transformation was found involved in the decarbonylation process, which is responsible for the sequence of alkyne insertion/decarbonylation. Oxidative addition of C(carbonyl)-C(carbonyl) bond to Ru(0) and the Ru(II)-C(sp(2)) bond formation were confirmed to be favorable for the decarbonylation, meanwhile oxidative addition of C(carbonyl)-C(carbonyl) bond to Ru(0) is likely to be the rate-determining step for the entire catalytic cycle. It is predicted that the regeneration of the catalyst was achieved by the oxidation of air oxygen in the absence of other oxidants. The current theoretical study provides new insights into the decarbonylative annulation.

Automated summary

Density functional theory calculations were used to explore the Ru-catalyzed decarbonylative annulation reaction, revealing a Ru(II)-Ru(0)-Ru(II) transformation. The oxidative addition of C(carbonyl)-C(carbonyl) bond to Ru(0) was found to be favorable, while the regeneration of the catalyst was predicted to be achieved by the oxidation of air oxygen. This study provides new insights into the decarbonylative annulation.