Jun-ichi Tateiwa

Boration of an α,β-enone using a diboron promoted by a copper(I)–phosphine mixture catalyst

Abstract The Cu(I)-catalyzed boration of an α,β-enone using a diboron is described. Combination of a Cu(I) salt and tributylphosphine is an effective catalyst system, though the individual use of Cu(I) and tributylphosphine is not active for the reaction.

An unprecedented catalytic reaction using gold(I) complexes

Abstract This paper describes an unprecedented catalytic reaction using Au(I) complexes. Au complexes efficiently catalyze dehydrogenative dimerization of trialkylstannanes. Catalytic activity of the Au(I) complex toward dehydrogenative dimerization of the trialkylstannane is extremely high (0.1 mol%, 48 h) comparable to that of Pd catalysts. The synthetic generality of this reaction was demonstrated for the reaction using tributyl-, trioctyl-, triphenylstannane.

Highly stereoselective metathesis reaction between optically active hydrosilane and copper(I) salt in 1,3-dimethyl-2-imidazolidinone☆

Abstract Highly stereoselective metathesis reactions between optically active silyl compounds and copper(I) salts in 1,3-dimethyl-2-imidazolidinone (DMI) are reported. The substitution reaction of (+)-α-naphthylphenylmethylsilane with a mixture of lithium tert-butoxide and copper(I) salt smoothly proceeded in DMI to give the corresponding silyl ether with a high degree of retention of the configuration in a quantitative yield. The use of DMI as a solvent and the presence of a chloride ion are necessary for this reaction. An optically active alkynylsilane also reacted with the mixed reagent to afford the corresponding silyl ether. A mechanism of oxidative addition of the hydrosilane and reductive elimination of the silyl ether on copper is proposed.

Selective O-acylation of silyl enol ethers with acid halides mediated by a copper(I) salt☆

A new selective synthetic method of enol esters (O-acylated products) from silyl enol ether and acid chloride in the presence of CuCl is described. This reaction proceeds smoothly in DMI (1,3-dimethyl-2-imidazolidinone) but not in a less polar solvent. The silicon-copper exchange reaction pathway is proposed for this transformation as in the cases of hydrosilane and alkynylsilane which were previously reported.

Pentacoordinate Organosilicate-Catalyzed Michael Addition of β-Keto Esters to 3-Buten-2-one

The Michael addition of β-keto esters to 3-buten-2-one (methyl vinyl ketone, MVK) in the presence of a pentacoordinate organosilicate was investigated. Ethyl 2-oxo-1-cyclohexanecarboxylate reacted with MVK in the presence of potassium bis(1,2-benzenediolato)phenylsilicate to furnish ethyl 2-oxo-1-(3-oxo-1-butyl)-1-cyclohexanecarboxylate in 96% isolated yield. Ethyl 2-oxo-1-cyclopentanecarboxylate, ethyl 2-oxo-1-cyclooctanecarboxylate, ethyl 2-methyl-3-oxobutanoate, and ethyl 2-ethyl-3-oxobutanoate also reacted with MVK in the presence of potassium bis(1,2-benzenediolato)phenylsilicate to produce the corresponding 1,4-adduct in moderate to good yields. In these reactions, the silicate might work as both a Lewis acid catalyst and a Bronsted base catalyst at the same time.

First gold complex-catalysed selective hydrosilylation of organic compounds

The first examples of the hydrosilylation of organic compounds such as aldehydes and an aldimine using a catalytic amount of a gold complex, which accomplished versatile regio- and chemo-selective reduction of carbonyl compounds, are described.

Intramolecular hydrogen bond-promoted C–C bond formation: reaction rate enhancement and regioselective allylation of carbonyl compounds

An intramolecular hydrogen bond promotes rate enhancement in both the allylation and the reduction of carbonyl compounds and also regioselective allylation.