Markovnikov Hydrosilylation of Alkenes: How an Oddity Becomes the Goal

Abstract

Over the years, hydrosilylation of terminal alkenes has emerged as one of the most prominent applications of homogeneous catalysis. While most of the relevant reports concern β-selective hydrosilylation, yielding linear products which are of industrial importance, the opposite selectivity is also gaining increasing interest and sets the scene for the next challenges. Markovnikov hydrosilylation of alkenes, especially in its asymmetric variant, has become the aim of development of new catalytic systems successfully implementing base-metal complexesone of the most prominent trends in contemporary catalysis. In this Perspective, we present the current state of this topic and the way it has been achieved, with special emphasis put on the issues still unresolved and prospective directions of development based on the trends present in the literature, but without unnecessary attention to some details of only historical significance.

The selective hydrosilylation of norbornadiene-2,5 by monohydrosiloxanes

“…Various compounds of transition metals have previously been proved to be effective catalysts for the hydrosilylation of olens and unsaturated polymers. 1,5,30 The most active of them are Pt salts and its complexes. Catalysts based on other Pt-group metals are slightly less active.…”

“…The hydrosilylation of alkenes and dienes is a powerful synthetic tool for the production of various organosilicon compounds [1][2][3] and modication of the properties of the material. 4,5 Among the low-molecular-weight organosilicon compounds, alkenylsilanes are the most commonly used building blocks in organic synthesis owing to their versatile reactivity.…”

“…1,1,1,3,5,5,5-Heptamethyl-3-(5-exo-norbornene-2-yl)trisiloxane. Yield: 83% (78% exo-norbornene, 5% nortricyclane) 1. H NMR (d, ppm, CDCl 3 ): 6.11 (m, 1H, C(2,3)H), 5.90 (m, 1H, C(2,3)H), 2.87 (m, 1H, C(1,4)H), 2.77 (m, 1H, C(1,4)H), 1.64-1.57…”

The structural diversity of heterocycle-fused potassium cyclopentadienides

“…The K-O, K-C distances and bond lengths within the anion are given in Table 5 and in Scheme 5, correspondingly (other parameters are presented in Table S5 in the ESI †). Due to steric hindrance, the phenyl group is rotated by 35.80 7 N)] unit is sterically crowded enough not to form coordination polymers, yet the K + coordination sphere is insufficiently saturated, and K + has a low formal coordination number (7). Therefore, the anion [C 21 H 14 N] À (atoms N1, C16, C15, C5, C6) and the cation [K(diglyme)(THF)] + of two different molecules, which are related by an inversion center, demonstrate weak electrostatic intermolecular interactions that lead to association into a dimeric unit (Fig.…”

“…Sandwich and half-sandwich complexes of transition metals and f-elements are actual catalysts of industrially important processes, such as olen [1][2][3] and diene 4 polymerization, olen epoxidation, 5,6 hydrosilylation, 7 etc. The remarkable variety of cyclopentadiene-type ligands obtained to date is due to the catalytic application of the corresponding complexes: substituted cyclopentadiene, indene and uorene are h 5 -bound ligands that successfully provide the "basic" steric environment of the catalytic center and affect the catalytic activity, regioselectivity and stereoselectivity.…”