Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

Abstract

The combined Lewis acid Me3SiBr/InCl3 shows unique performance in multireactions. The topology and catalytic properties of Me3SiBr/InCl3 were investigated by DFT method for clarifying the nature of chemical bonds and interactions. Quantum theory of atoms in molecules (QTAIM) analysis showed that the interaction between Me3Si‐halide and In‐trihalide mainly belongs to the closed‐shell interaction. Natural bond order of Br─In is 0.610 in INT_0 while natural bond order of Cl─In in INT_1 is only 0.081 at SMD‐ωB97XD/def2‐SVP level. The coupling reaction mechanism of alcohol and allyltrimethylsilane catalyzed by the complex of Me3SiBr/InCl3 was investigated with DFT method. The combined Lewis acid activates the hydroxyl group by strong coordination to silicone center, which leads to the generation of carbocation. Me3Si+ moiety from the combined Lewis acid is consumed and converts into the side product Me3SiOSiMe3. Furthermore, the reactant allyltrimethylsilane is introduced into the system to bring out the final product, and the complex Me3SiBr/InCl3 is reproduced at the same time. The combined Lewis acid Me3SiBr/InCl3 not only works as the catalyst for the reaction but also involves in the generation of side product.

Acetate/Alkoxide/Halide Shuttle Systems Mediated by Lewis Acid Catalysts for Insertion Reaction of a One-Carbon Unit into Carbon–Carbon or Carbon–Halogen Bonds

“…Since the Lewis acidity of InI 3 is not high enough to abstract AcO or MeO group, which is a poorer leaving group than halide groups, the activation of alkyl acetates or ethers requires the combination of InI 3 with Me 3 SiBr, which exhibits a higher Lewis acidity than InI 3 . 6 The AcO group coordinates to the Si center, then abstraction of the AcO group occurs to generate carbocation C and InI 3 -Me 3 SiBr-OAc ate complex D. 14 The electrophilic addition of cation C to -diazo ester 2a gives diazonium E. The migration of a Ph group to the di-azonium carbon and concerted denitrogenation proceeds to generate benzyl cation intermediate F. The AcO -, which is captured by Me 3 SiBr-InI 3 complex, attacks the carbocation intermediate F to give elongated product 3a, and InBr 3 and Me 3 SiBr are regenerated. The diastereoselectivity would be determined at the nucleophilic addition of AcOto the carbocation intermediate.…”

Combined Lewis Acid Catalyzed Diastereoselective Halogenative Cascade Annulation of Enone-Tethered Cyclohexadienones

“…11 Interestingly, an Indium(III)-catalyst works effectively along with trimethylsilyl halide as a combined Lewis acid catalyst, which shows a unique ability to promote the reactions. 12 Over the past two decades, various applications such as Sakurai−Hosomi reaction, coupling reactions, Friedel− Crafts reactions, Michael addition of enolates, Prins cyclizations, and [2 + 2]-cycloadditions have been demonstrated by Lee, Baba, Loh, Song, and other research group using this combined Lewis acid catalysis. 13 However, there is no report on the halogenation of α,β-unsaturated carbonyl compounds.…”

“…Among other group-III metals, Indium salts had been scarcely explored as a catalyst in organic chemistry due to their moderate Lewis acidity . Interestingly, an Indium­(III)-catalyst works effectively along with trimethylsilyl halide as a combined Lewis acid catalyst, which shows a unique ability to promote the reactions . Over the past two decades, various applications such as Sakurai–Hosomi reaction, coupling reactions, Friedel–Crafts reactions, Michael addition of enolates, Prins cyclizations, and [2 + 2]-cycloadditions have been demonstrated by Lee, Baba, Loh, Song, and other research group using this combined Lewis acid catalysis .…”