Highly chemoselective palladium-catalyzed conjugate reduction of. cap alpha. ,. beta. -unsaturated carbonyl compounds with silicon hydrides and zinc chloride cocatalyst

Journal Article · Tue Nov 11 23:00:00 EST 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00283a029· OSTI ID:6996830

Keinan, E; Greenspoon, N

A three-component system comprised of a soluble palladium catalyst, hydridosilane, and zinc chloride is capable of efficient conjugate reduction of ..cap alpha..,..beta..-unsaturated ketones and aldehydes. The optimal set of conditions includes diphenylsilane as the most effective hydride donor, any soluble palladium complex in either the O or II oxidation state, when it is stabilized by phosphine ligands, and ZnCl/sub 2/ as the best Lewis acid cocatalyst. The reaction is very general with respect to a broad range of unsaturated ketones and aldehydes, and it is highly selective for these Michael acceptors, as reduction of ..cap alpha..,..beta..-unsaturated carboxylic acid derivatives is very sluggish under these conditions. When dideuteriodiphenylsilane is used to reduce unsaturated ketones, deuterium is stereoselectivity introduced at the less-hindered fact of the substrate and regioselectively at the ..beta..-position. Conversely, when reductions are carried out in the presence of traces of D/sub 2/O, deuterium incorporation occurs at the ..cap alpha..-position. On the basis of deuterium-incorporation experiments and /sup 1/H NMR studies a catalytic cycle is postulated in which the first step involves reversible coordination of the palladium complex to the electron-deficient olefin and oxidative addition of silicon hydride to form a hydridopalladium olefin complex.

• Research Organization: Weizmann Institute of Science, Rehovot, Israel
• OSTI ID: 6996830
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:23; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALDEHYDES
CARBONYLS
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DATA
ELEMENTS
EXPERIMENTAL DATA
HALIDES
HALOGEN COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
KETONES
LEWIS ACIDS
LIGANDS
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PALLADIUM
PLATINUM METALS
REDUCTION
SILANES
SILICON COMPOUNDS
TRANSITION ELEMENTS
VALENCE
ZINC CHLORIDES
ZINC COMPOUNDS
ZINC HALIDES