3‐Silylated Cyclohexa‐1,4‐dienes as Precursors for Gaseous Hydrosilanes: The B(C₆F₅)₃‐Catalyzed Transfer Hydrosilylation of Alkenes

Abstract

Set Me3SiH free! The strong Lewis acid B(C6F5)3 catalyzes the release of hydrosilanes from 3‐silylated cyclohexa‐1,4‐dienes with concomitant formation of benzene. Subsequent B(C6F5)3‐catalyzed SiH bond activation allows for alkene hydrosilylation (see scheme). The net reaction is an ionic transfer hydrosilylation. The new technique is particularly attractive in the case of otherwise gaseous, highly flammable hydrosilanes.

Fifty Years of Hydrosilylation in Polymer Science: A Review of Current Trends of Low-Cost Transition-Metal and Metal-Free Catalysts, Non-Thermally Triggered Hydrosilylation Reactions, and Industrial Applications

“…In a subsequent study, they performed a systematic study of various Lewis acids that could be used for this particular reaction [68]. Simonneau and Oestrich [67] reported the use of 3-silylated cyclohexadi-1,4-enes as precursors for the in-situ generation of the gaseous hydrosilanes Me 3 SiH and Me 2 SiH (Figure 28). They used 5 mol % of the Lewis acid catalyst B(C 6 F 5 ) 3 with various alkene and styrene derivatives at r.t.…”

B(C6F5)3‐Catalyzed Transfer Hydrogenation of Imines and Related Heteroarenes Using Cyclohexa‐1,4‐dienes as a Dihydrogen Source

“…This trend is in accordance with the dramatic effect of a silicon group in the bisallylic position, allowing for hydride abstraction at room temperature. [13] The reaction temperature of 125 8C is in the range of those reported for the B(C 6 F 5 ) 3 -catalyzed imine hydrogenations under moderate dihydrogen pressure. [9] Reactions were routinely maintained at that temperature for 18 h but monitoring the progress by 1 H NMR spectroscopy indicated full conversion after 4 h (1 b, Scheme 2).…”

“…[13] The C(sp 3 )ÀH bond in I develops hydridic character through hyperconjugation with the C(sp 3 À as the counteranion, II collapses to liberate the free hydrosilane along with benzene at room temperature. The net reaction is catalytic in B(C 6 F 5 ) 3 and was then coupled with B(C 6 F 5 ) 3 -catalyzed alkene hydrosilylation, thereby enabling the previously unprecedented ionic transfer hydrosilylation.…”

Metal‐Free Hydrosilylation Polymerization by Borane Catalyst

“…[13] After the initial finding of B(C 6 F 5 ) 3 -catalyzed hydrosilylative reduction of aldehydes pioneered by Piers and Parks, [14] several Lewis acidic main-group compounds,s uch as boranes, [13a-d] silanes, [13e] and organophosphonium cations [13f] have been reported to catalyze hydrosilylations. [15] Unlike transition-metal catalysts which trigger the reaction by an oxidative insertion into aS i À Hb ond (Chalk-Harrold mechanism), [16] the electron-deficient Lewis acids,representatively B(C 6 F 5 ) 3 ,a ctivate aS i ÀHb ond via h 1 -coordination to add across unsaturated bonds (Scheme 2).…”