DFT study on the ruthenium-catalyzed decarbonylative annulation of an alkyne with a six-membered hydroxychromone via C-H/C-C activation

We report a density functional theory study on the ruthenium-catalyzed decarbonylative annulation of an alkyne with a six-membered hydroxychromone via C-H/C-C activation. The plausible catalytic cycles involve O-H deprotonation, C-H activation, alkyne insertion and formal [3 + 2] cycloaddition, oxidative insertion and decarbonylation, reductive annulation and the recovery of the catalyst. The calculations confirmed that there are two C-C bonds to be broken to finish the decarbonylation, and to break the C-C bond, originally a C=C double bond in la, is the favorable reaction path. Since there is no oxidant added to the reaction system, the O(2 )molecules in the air help the separation of product 3a and the recovery of the active catalyst, in which triplet and singlet surface crossing would exist. The steady-state approximation and modified energy span model have been employed to calculate the apparent activation free energy of the catalytic cycle.

Automated summary

This study investigated the ruthenium-catalyzed decarbonylative annulation of an alkyne with a hydroxychromone, revealing key steps such as the breaking of C-C bonds and the favorable reaction pathways. The calculations also utilized the steady-state approximation and modified energy span model to determine the apparent activation free energy of the catalytic cycle.