Makoto Itagaki

Kinetic Resolution of Racemic α-Arylalkanoic Acids with Achiral Alcohols via the Asymmetric Esterification Using Carboxylic Anhydrides and Acyl-Transfer Catalysts

A variety of optically active carboxylic esters are produced by the kinetic resolution of racemic alpha-substituted carboxylic acids using achiral alcohols, aromatic or aliphatic carboxylic anhydrides, and chiral acyl-transfer catalysts. The combination of 4-methoxybenzoic anhydride (PMBA) or pivalic anhydride with the modified benzotetramisole-type catalyst ((S)-beta-Np-BTM) is the most effective for promotion of the enantioselective coupling reaction between racemic carboxylic acids and a novel nucleophile, bis(alpha-naphthyl)methanol, to give the corresponding esters with high ees. This protocol was successfully applied to the production of nonracemic nonsteroidal anti-inflammatory drugs from racemic compounds utilizing the transacylation process to generate the mixed anhydrides from the acid components with the suitable carboxylic anhydrides.

Efficient dimerization of propylene affording 2,3-dimethylbutenes by fluorinated alcohol modified nickel-phosphine catalyst system containing strong sulfonic acid and/or dialkyl sulfates

A remarkable increase of both catalytic activity and the selectivity of dimers has been found for propylene dimerization affording 2,3-dimethylbutenes by a nickel-phosphine catalyst system composed of nickel naphthenate/P(cyclo-C6H11)3/A lEt3/ (CF3)2CHOH in the presence of CF3SO3H and/or Me2SO4: a combination of these effective additives also enhanced the reaction rates.

Fluorinated alcohol modified nickel–phosphine catalyst system for efficient dimerization of propylene

Abstract Remarkable increase of the catalytic activity (turnover number for the formation of C 6 olefins or 2,3-dimethylbutenes) as well as the selectivity of C 6 olefins based on the reacted propylene has been exhibited for propylene dimerization by using the catalyst system composed of nickel naphthenate, tert -phosphine, AlEt 3 , and (CF 3 ) 2 CHOH in the presence of CF 3 SO 3 H and/or Me 2 SO 4 . It turned out that the product distributions in dimers depended upon the kind of tert -phosphine ligand used. 31 P -NMR spectrum of the catalyst solution showed a peak at 33 ppm ( J P–H =458 Hz): the corresponding peak on 1 H -NMR was observed at 4.3 ppm which could be confirmed by 2D NMR ( 31 P – 1 H , COSY) and 1 H -NMR with 31 P (33 ppm) selective decoupling. The 27 Al -NMR spectrum of the same solution showed a relatively sharp resonance at 60 ppm.