Diastereo- and Enantioselective Rh-Catalyzed Si−H Insertion of N -Triftosylhydrazones: From Carbon to Silicon-Stereogenic Centers

Abstract The carbene insertion into Si−H bonds has long been established as a powerful method for constructing organosilicon compounds; however, achieving stereoselective transformations remains challenging. This difficulty stems from the inherent kinetic control required for asymmetric induction at prochiral metal-carbene intermediates, coupled with the need for enantioselective metal-catalyzed Si−H bond activation. Here, we report a strategy that leverages fluorine effects to achieve highly enantio- and diastereoselective carbene insertion into Si−H bonds. In this approach, metal-carbene intermediates generated in situ from N-(ortho-trifluoromethyl)arylsulfonyl (N-Tfs) hydrazones are stabilized by the trifluoromethyl group, while weak aromatic interactions promote enantioselective Si−H bond insertion. Notably, using racemic monohydrosilanes bearing four distinct substituents on the silicon center, the rhodium catalyst not only induces chirality at the carbene carbon but also efficiently differentiates the silicon-centered enantiomers via kinetic resolution, achieving selectivity factors up to s = 397 and thus establishing both the carbon stereocenter and stereogenic silicon center. Mechanistic studies indicate that this pronounced enantiodiscrimination arises from synergistic aromatic interactions between the substrates and a chiral dirhodium catalyst equipped with four aromatic rings that function as a chiral π-wall. These interactions stereoselectively promote a concerted fashion of carbenoid insertion into racemic hydrosilanes for kinetic resolution of one hydrosilane enantiomer. Our findings establish trifluoromethyl-group-enabled aromatic-interaction-driven control as a unified strategy for dictating stereochemical outcomes in metal-carbene-mediated Si−H insertion reactions.