Earth-abundant transition metal catalysts for alkene hydrosilylation and hydroboration

Abstract

The addition of a silicon-hydrogen or a boron-hydrogen bond across a carbon-carbon multiple bonds is a well-established method for the introduction of versatile silane and borane functional groups to base hydrocarbon feedstocks. Transition metal catalysis, historically with precious second- and third- row transition metals, has been used to broaden the scope of the hydrofunctionalization reaction, improve reaction rate and enhance selectivity. The anti-Markovnikov selectivity of platinum-catalyzed hydrosilylation of alkenes, for example, is an enabling synthetic technology in the multibillion-dollar silicones industry. Increased emphasis on sustainable catalytic methods and more economic processes has shifted focus to catalysis with more earth-abundant transition metals such as iron, cobalt and nickel. This review describes contemporary approaches and offers a contextual analysis of catalytic alkene hydrosilylation and hydroboration reactions using first-row transition metals. Emphasis is placed on defining advances in the field, what constitutes catalyst cost, safety, and important design features to enable precious metal-like reactivity, as well as new chemistry that is unique to first-row transition metals.

Iridium-catalyzed Markovnikov hydrosilylation of terminal alkynes achieved by using a trimethylsilyl-protected trihydroxysilane

“…3). Considering the widespread hydroxyl and amino groups in biomolecules, propargyl derivatives from them were selected as representatives in most cases (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45). Propargyl ether analogues of menthol, carveol, prolinol, glucose and glucofuranose were successfully transformed into corresponding α-vinylsilanes in good to excellent yields (30-34).…”

“…1 H and 13 C NMR Spectra of all hydrosilylation products and unknown substrate were provided. 13 C DEPT135 NMR Spectra of products 3,4,5,6,7,9,10,12,13,15,19,20,21,26,30,31,32,36,37,38,39,40,41,42,44,45 were afford. 2D NOESY Results of products 1 and 27 are also provided.…”

“…Highly regioselective silylcupration of terminal alkynes reported by Loh is another efficient approach to α-vinylsilanes 24 . However, further commercial and industrial use of these methods is limited by their own properties, such as the unstability of Ru catalysts, requirement of complex ligands and low efficiency towards alkyl alkynes in Co catalysis 30 , usage of expensive PhMe 2 SiBpin as silyl source and high catalyst loading in Cu catalysis. New strategies for Markovnikov hydrosilylation of alkynes that require simple catalysts or ligands, low-cost silanes, but have outstanding tolerance towards various functional groups and suit for large-scale operations, are still in urgent desire.…”

A Dicationic Bismuth(III) Lewis Acid: Catalytic Hydrosilylation of Olefins

“…Recent research in this area has focused on the development of earth abundant transition metal catalysts of Fe, Co and Ni. [58] Due to their Lewis acidity, few s- [59] and p-block [60][61][62][63][64][65] compounds have been explored as possible alternatives to the existing catalysts.…”

Cycloaddition Chemistry of a Silylene‐Nickel Complex toward Organic π‐Systems: From Reversibility to C−H Activation

“…This is born out experimentally:d espite the apparent CÀCs ingle bond present in the cyclic core of 7,d issolution of pure crystals of this compound in C 6 D 6 led to the generation of small amounts of both 1 and C 2 H 4 .T hus, to our surprise, the cycloaddition of ethylene to 1 is in fact reversible. [24] Circumstantial evidencef or the intermediate generation of 8 came from the isolationo f one or two crystalso ft his compound by the low-temperature reactiono f1 with excess ethylene, followed by storagea t À30 8Cfor two weeks. Although a computational investigation for the reaction of 1 with ethylene suggested that 7 may readily undergo af urtherc ycloaddition event with ethylene to form the six-membered metallasilacycle 8 (Scheme 3, Figure 3), we were surprised to find that the experimentally observed product from the reaction of 1 with excess ethylene is the alkene-Ni 0 p-complex 9.…”