Rhodium‐Catalyzed Dynamic Kinetic Asymmetric Hydrosilylation to Access Silicon‐Stereogenic Center

Abstract

Strategies on the construction of enantiomerically pure silicon‐stereogenic silanes generally relies on desymmetrization of prochiral and symmetric substrates. However, dynamic kinetic asymmetric transformations of organosilicon compounds have remained underdeveloped and unforeseen owing to a lack of an effective method for deracemization of the static silicon stereocenters. Here we report the first Rh‐catalyzed dynamic kinetic asymmetric intramolecular hydrosilylation (DyKAH) with “silicon‐centered” racemic hydrosilanes that enables the facile preparation of silicon‐stereogenic benzosiloles in good yields and excellent enantioselectivities. The special rhodium catalyst controlled by non‐diastereopure‐type mixed phosphine‐phosphoramidite ligand with axial chirality and multiple stereocenters can induce enantioselectivity efficiently in this novel DyKAH reaction. Density functional theory (DFT) calculations suggest that the amide moiety in chiral ligand plays important role in facilitating the SN2 substitution of chloride ion to realize the chiral inversion of silicon center.

Research Progress on New Catalytic Reaction Systems for Asymmetric Synthesis of Silicon-Stereogenic Center Containing Compounds

“…基于"硅中心"外消旋氢硅烷的动力学或 动态动力学转化策略, 通过不对称催化消旋硅中心的 Si-H 键活化来构建硅立体中心是一项极具挑战性的研 究课题. 2022 年, 徐利文课题组 [28] 开创性地发展了一种 消旋单氢硅烷的动态动力学不对称硅氢加成反应, 成功 合成了一系列硅立体中心手性硅杂环化合物(up to 89%…”

Catalytic Kinetic Resolution of Monohydrosilanes via Rhodium‐Catalyzed Enantioselective Intramolecular Hydrosilylation

“…Currently, the majority of catalytic processes for the preparation of silicon‐stereogenic organosilanes relies on enantioselective desymmetrization of prochiral precursors with two identical substitutes attached to the Si( sp 3 )‐atom center, due to the low stability and inaccessibility of silicon‐carbon or silicon‐heteroatom multiple bonds ( sp 2 ‐silicon center) [2–5] . Very recently, the catalytic dynamic kinetic asymmetric transformation (DYKAT) of racemic organosilanes has been demonstrated by the Xu group [6a] and the List group, [6b] providing another promising supplement for the construction of silicon‐stereogenic organosilanes (Scheme 1a). However, the direct catalytic kinetic resolution of racemic organosilanes with high stereoinduction has not been well‐documented, although kinetic resolution (KR) of racemates represents a practical process for construction of two enantioenriched silicon‐stereogenic compounds bearing different functionalities simultaneously [7] .…”

Enantioconvergent construction of stereogenic silicon via Lewis base-catalyzed dynamic kinetic silyletherification of racemic chlorosilanes

“…Most reactions are catalyzed by expensive palladium or rhodium catalysts, therefore limiting the scalability and practicality of the strategy. A third strategy: enantioconvergent transformation of racemic organosilanes, has rarely been considered, except for recent progress in a Rh-catalyzed dynamic kinetic asymmetric intramolecular hydrosilylation of alkynes with racemic hydrosilanes 42 , and dynamic kinetic asymmetric transformation of racemic tetraorgano allyl silanes into silylethers using imidodiphosphorimidate (IDPi) catalysts 43 .…”