Vinyl- and Arylsilicon, germanium, and boron Compounds

Abstract

This chapter summarizes the recent developments of the most efficient methods for the synthesis of vinyl- and aryl-substituted silicon, germanium and boron compounds since the publication of COFGT (1995) and consists of three parts: boron, silicon and germanium derivatives, respectively. The first part presents advances in classical methods, such as hydroboration and haloboration of alkynes, transmetallation of boron alkoxides and halides with alkenyl and aryl metals, and transformations of organoboranes. New approaches involve borylation of arenes, the metathesis reaction of alkenylboronates with alkenes, the cross-coupling reaction of boron compounds with diazonium salts, alkenyl and aryl halides, and triflates. The addition of boron-element bond to CC multiple bonds leads to alkenylboranes containing reactive carbon-element bond. Many efficient stereo- and regioselective methodologies for synthesis of alkenylsilanes-vinylsubstituted silanes involve classical stoichiometric routes from organometallic reagents and more recently, transition metal-catalyzed transformations of alkynes, silylalkynes, alkenes and silicon derivatives such as hydrosilylation, bissilylation, silylmetallation, carbosilylation and silylcarbonylation of alkynes as well as hydrogenation, hydrometallation and other addition reaction of silyl alkynes. The reaction of alkenyl metals with silicon reagents as well as transformation of vinylsilanes, alkenes and allenes via many catalytic reactions such as dehydrogenative silylation, cross-metathesis, trans-silylation, cross-coupling reaction and others, complete the synthetic methods of alkenylsilanes which are discussed. Arylsilanes can be prepared via Wurtz–Fittig coupling, silylation of aryl metals, electrophilic and nucleophilic aromatic substitutions, cycloaddition reactions and TM-catalyzed coupling of aryl derivatives with silicon compounds. Transformations of alkenyl metals, alkynes, or alkynylgermanes remain the most commonly used methods for synthesis of vinylgermanes. Reported applications of substitution of halogermanes with aryl metals (mainly magnesium and lithium reagents)—the fundamental way of arylgermanes synthesis—are presented together with the less common synthetic procedures such as palladium-catalyzed coupling of germanes with aryl halides or insertion of germylenes into aryl halides.