The development of novel methodologies to access chiral silicon molecules remain limited, focusing primarily on hydrosilylation, or hydrolysis of tetrahedral silanes. Expanding the chemical space of chiral silicon-based molecules can aid in catalysis, drug discovery, and materials development. Metal-catalyzed carbene insertion reactions are an established method used to desymmetrize prochiral tetrahedral carbon centers in organic molecules, with selected precedent for silicon. In this study, alkyl-arylsilanes have been demonstrated to generate chiral benzhydryl silanes using dirhodium(II) carboxylate catalysts with slow addition of diphenyldiazomethane. A screen of ligands revealed tetrakis[<i>N</i>-tetrachlorophthaloyl-<i>tert</i>-leucinato]dirhodium in non-polar solvents provide optimal levels of selectivity and reactivity. A series of prochiral silanes were synthesized and screened to understand the impact of steric and electronic effects on selectivity, in addition to structural variation of the diazo precursor. The conditions were also expanded to demonstrate the reaction of alkoxy silanes and siloxanes to understand the effect of oxygenation on selectivity. Transformation of silane products to silanols, siloxanes, and silyl ethers will be discussed.

Enantioselective carbene insertion into silanes: Access to chiral benzhydryl silanes

2019 Fall National Meeting

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