Mechanistic Study on CpRh(III)-Catalyzed [3+2] Annulation of Aniline Derivatives with Vinylsilanes: A DFT Study

The rhodium-(III)-catalyzed reactionof aniline derivatives thatcontain a pyrimidine-directing group with vinylsilanes results inthe formation of C3-substituted indoline derivatives. The reactionpath and formation of the indoline product with density functionaltheory calculations were analyzed. This study reveals that the wholecatalysis can be characterized in the following stages: (I) C-Hactivation via concerted metalation deprotonation, (II) 2,1-vinylsilaneinsertion, (III) deprotonation of the NH amide proton, (IV) the oxidationof Ag+, and (V) reductive elimination. These steps arekinetically and thermodynamically feasible for experimental realizationunder mild conditions, and the insertion step with a barrier of 22.0kcal/mol should not only be the critical step of regioselectivitybut also the rate-determining step during the whole catalysis. Computationsreveal that the Ag+ oxidation can accelerate the reductiveelimination step after the formation of natural intermediate, thushighlighting the role of Ag+ as a catalytic promoter forthe oxidatively induced reactivity of the Rh catalyst in C3-substitutedindoline synthesis.

Automated summary

This study explored the reaction mechanism and formation of C3-substituted indoline derivatives from aniline derivatives containing a pyrimidine-directing group and vinylsilanes. The reaction involves several steps including C-H activation, 2,1-vinylsilane insertion, NH amide proton deprotonation, Ag+ oxidation, and reductive elimination. The insertion of the vinylsilane is not only the critical step for regioselectivity but also the rate-determining step. The computational analysis demonstrates that the Ag+ oxidation can accelerate the reductive elimination step, highlighting the role of Ag+ as a catalytic promoter.