Theoretical Study on Si−Cl Bond Activation in Pd‐Catalyzed Cross‐Coupling of Chlorosilanes with Organoaluminum

Abstract

The catalytic cross-coupling of chlorosilanes has recently emerged as an efficient method for the synthesis of organic silicon compounds. Direct SiÀ Cl bond activation by transition metals is a key elementary reaction in these methods. This theoretical study aimed to elucidate the mechanism of activation of the strong SiÀ Cl bond in Pd-catalyzed coupling reaction to gain insights for rational catalyst design. Our results suggest two plausible pathways for the bond activation: (i) trans-oxidative addition and (ii) S N 2-type oxidative addition assisted by a Lewis acid. With an increase in Cl substituents of chlorosilanes, trans-oxidative addition highly feasible due to their higher Lewis acidities, in which the facile formation of the Pd!Si interaction enables the smooth activation of the SiÀ Cl bond. The general mechanism of direct SiÀ Cl bond activation presented here may prove useful for the rational design of catalysis in the future.

Nickel‐Catalyzed Reductive Coupling of Chlorosilanes

“…[21] The oxidative addition of ArÀ X to Ni(0), followed by reduction with Mn, affords nucleophilic species ArÀ Ni(I) B. The S N 2 oxidative addition of chlorosilanes to ArÀ Ni(I), [24] possibly through a five-coordinate nickel Scheme 12. Synthetic applications of reductive Csp 3 À Si coupling of chlorovinylsilanes.…”

“…[21] The oxidative addition of Ar−X to Ni(0), followed by reduction with Mn, affords nucleophilic species Ar−Ni(I) B . The S N 2 oxidative addition of chlorosilanes to Ar−Ni(I), [24] possibly through a five‐coordinate nickel intermediate C , gives complex D [6a] . Reductive elimination of complex D would afford the desired product.…”

Halide‐Triel Bonds between R3SiX (X=F, Cl and Br) and TrY3 (Tr=Al, B and Ga)

“…Activation of Si-halogen bond is of great importance in transition metal catalysed cross-coupling reactions. [34] Especially, activation of SiÀ F bond demands more attention because many intermediate transformations in silicon chemistry end up in fluorosilanes. [3] Results of our study might help in understanding the role of Lewis acid in the Si-halogen bond activation process which, in turn, would become useful for efficient catalyst design.…”

Nickel-Catalyzed Reductive [4 + 1] Sila-Cycloaddition of 1,3-Dienes with Dichlorosilanes

“…The proposed catalytic cycle is shown in Scheme . The reaction of Ni(0) with dichlorosilane, , followed by reduction with Mn, affords Si–Ni­(I) . The silyl dimer might be derived from this nickel species by reaction with chlorosilane .…”