Enantioselective Hydrosilylation with Chiral Frustrated Lewis Pairs

Reversible Heterolytic Si–H Bond Activation by an Intramolecular Frustrated Lewis Pair

“…Therefore, our disclosure of a particularly mild and reversible Si-H bond cleavage of the silanes PhSiH 3 and Ph 2 SiH 2 by our reactive intramolecular frustrated P/B Lewis pair Mes 2 PCH 2 CH 2 B(C 6 F 5 ) 2 (7) is quite remarkable. The reversibility of Si-H bond breaking needs to be taken into account when planning FLPcatalyzed hydrosilylation reactions and can become a favorable feature when FLP-induced transformations of silanes themselves are considered [15,31,38]. In this context, fundamental understanding of the Si-H bond activation mode by FLPs will provide an experimental basis for useful developments.…”

“…In a recent example, Alcarazo and co-workers reported the activation of the Si-H bonds in ethyldimethylsilane (EtMe 2 SiH) and diphenylsilane (Ph 2 SiH 2 ) by the carbon(0)/boranebased FLP hexaphenylcarbodiphosphorane/B(C 6 F 5 ) 3 (1) (Scheme 1, upper part) [37]. Klankermeyer et al extended the scope by showing that the intermolecular frustrated P/B Lewis pair tBu 3 P/B(C 6 F 5 ) 3 (3) is also capable of cleaving the Si-H bond in dimethylphenylsilane (Me 2 PhSiH) under mild conditions [38] (Scheme 1, lower part). The resulting zwit-Scheme 1.…”

Frustrated Lewis Pair Chemistry: Development and Perspectives

“…Utilization of the salt 77 b and the related 2-b-naphthyl derivative 80 as the catalyst gave slightly higher enantiomeric excesses of approximately 85 % (Scheme 31). [68] Similarly, Oestreich et al employed a chiral silane as the reductant either with B(C 6 F 5 ) 3 or a binaphthyl derived axially chiral borane. [69] Liu and Du [70] have used a chiral bis-borane which was generated in situ by hydroboration of a substituted divinylbinaphthyl derivative using HB(C 6 F 5 ) 2 .…”

B(C6F5)3‐katalysierte Hydrierung von Oximethern ohne Spaltung der N‐O‐Bindung

“…[9] Die Aktivierung der Si-H-Bindung wurde von Piers und Mitarbeitern nachgewiesen und erfolgreich in der katalytischen Iminreduktion eingesetzt. [10] Der heterolytische Bruch der H-H-Bindung wird in ähnlicher Weise unter Ausnutzung der einzigartigen Reaktivität frustrierter LewisPaare (FLPs) bewerkstelligt, [11] und etliche Systeme zur Hydrierung [12] von Iminen wurden mittlerweile beschrieben. [13] Elektronenarme Borane bewirken auch alleine die H-HBindungsaktivierung in Gegenwart Lewis-basischer Imine.…”