New catalytic route to (E)-β-silyl-α,β-unsaturated ketones

Silylative coupling of olefins with vinylsilanes in the synthesis of functionalized alkenes

Recent developments in the sequential synthetic strategies including ruthenium-catalyzed silylative coupling followed by desilylation, leading to π-conjugated organic derivatives are presented.

Reactivity of mer-hydrido(2-mercaptobenzoyl)tris(trimethylphosphine)cobalt(III) complex

The reactivity of mer-hydrido(2-mercaptobenzoyl)tris(trimethylphosphine)cobalt(III) complex 1 was intensively studied. A series of sulfur-coordinated organocobalt complexes (2-8) were obtained through the reactions of 1 with RX (RX = HCl, C2H5Br and CH3I), 2-(diphenylphosphanyl)phenol, 2-(diphenylphosphino)benzenethiol, and CO. The reaction of complex with ethynyltrimethylsilane under 1 bar of CO afforded a penta-coordinate cobalt(I) complex 11 via insertion reaction of C≡C bond of ethynyltrimethylsilane into Co-H bond and subsequent C,C-coupling reaction (reductive elimination). The formation mechanism of 11 was proposed and partly-experimentally verified. As an intermediate, the tetra-coordinate cobalt(I) complex 13 was isolated through the reaction of complex 1 with ethynyltrimethylsilane in the absence of CO. The crystal structures of complexes 2-4, 8, and 11 were determined by X-ray diffraction.

Copper(II)-catalyzed silylation of activated alkynes in water: diastereodivergent access to E- or Z-β-silyl-α,β-unsaturated carbonyl and carboxyl compounds

Copper(II)-catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me2 PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products.