Hydrosilylation of Alkenes with Early Main‐Group Metal Catalysts

Abstract

Clean conversion of conjugated alkenes with exclusive formation of one regioisomer is achieved by using a new class of hydrosilylation catalysts based on early main‐group metals (Ca, Sr, and K). The regioselectivity can be switched to the other isomer through the choice of the metal and solvent polarity.

Heterofunctionalization catalysis with organometallic complexes of calcium, strontium and barium

“…Based upon these experiments, Hill and coworkers suggested that the catalytic reaction proceeds via fast catalyst initiation, with turnover proceeding via s-bond metathesis and insertion reaction steps, with both steps being reversible under the catalytic conditions (figure 26). and phenylmethylsilane (figure 26; Buch et al 2006). Reactions proceeded with low catalyst loadings (0.5-10 mol%) under relatively mild conditions (50 • C, 0.5-16 h), with the strontium catalyst providing shorter reaction times than the calcium analogue (figure 27).…”

Calcium-mediated hydroboration of alkenes: “Trojan horse” or “true” catalysis?

“…In addition, Marks et al do not rule out the possibility that the lanthanide-hydride catalyst is present as a lanthanide borate species containing the (H 2 Bcat) À ion. We recently introduced the well-defined calcium hydride complex [DIPPnacnacCaH$(THF)] 2 (1) [22] (DIPPnacnac ¼ CH {(CMe)(2,6-iPr 2 C 6 H 3 N)} 2 ) and could show that such a species is an actual catalyst for alkene hydrosilylation [23] and hydrogenation [24]. As the key steps in catalysis based on organolanthanide and organocalcium chemistry are similar [25,26], we posed the question whether calcium-catalyzed alkene hydroboration would be feasible and efficient.…”

Alkali Metal Hydride Complexes: Well-Defined Molecular Species of Saline Hydrides

“…[ [59][60][61] Reactions of these silanes and KH also involve exchange processes of the organic substituents on silicon, and reduction to R 3 SiK species and polysilanes.…”

“…The majority of these catalytic transformations for the s-block elements are performed with Group 2 metal ions. [7,61,80] With the developed convenient silane method being used in many research groups around the world, more novel metal hydride complexes including those with alkali metal ions will be forthcoming and applied to stoichiometric and catalytic transformations. The cheap, abundant, non-toxic, and even biocompatible nature of some alkali metals such as Na and K will without doubt be further investigated by researchers for greener and more sustainable chemistry solutions.…”