Mechanistic investigation on rhodium(III)-catalyzed cycloaddition of 2-vinylphenol derivatives with ethyne or carbon monoxide by DFT study

• Published in: Chinese journal of chemical physics 2022-08, Vol.35 (4), p.685-696
• Main Authors: Zhang, Xing-hui, Wu, Xi, Shi, Hai-xiong
• Format: Article
• Language: English
• ISSN: 1674-0068; 2327-2244
• DOI: 10.1063/1674-0068/cjcp2009172

Rhodium-catalyzed cycloaddition reaction was calculated by density functional theory M06-2X method to directly synthesize benzoxepine and coumarin derivatives. In this work, we conducted a computational study of two competitive mechanisms in which the carbon atom of acetylene or carbon monoxide attacked and inserted from two different directions of the six-membered ring reactant to clarify the principle characteristics of this transformation. The calculation results reveal that: (i) the insertion process of alkyne or carbon monoxide is the key step of the reaction; (ii) for the (5+2) cycloaddition reaction of acetylene, higher energy is required to break the Rh−O bond of the reactant, and the reaction tends to complete the insertion from the side of the Rh−C bond; (iii) for the (5+1) cycloaddition of carbon monoxide, both reaction paths have lower activation free energy, and the two will generate a competition mechanism.