Michimasa Goto

The effect of vinyl esters on the enantioselectivity of the lipase-catalysed transesterification of alcohols

Abstract The enantioselectivity of the lipase from Pseudomonas cepacia (PCL) in the transesterification of 2-phenyl-1-propanol 1 was studied using a series of vinyl 3-arylpropanoates as acyl donors. The most enantioselective transesterification reaction of the alcohol was attained by using vinyl 3-( p -iodophenyl)- or 3-( p -trifluoromethylphenyl)propanoates, with enantiomer ratios, E , of 116 and 138, respectively. Vinyl 3-phenylpropanoate was also effective for the resolution of 1 mediated by lipases from P . fluorescens and porcine pancreas and for the PCL-catalysed transesterification of several 2-phenyl-1-alkanols. The enantiomeric resolution of 1 was practically carried out by the first enantioselective transesterification using PCL and vinyl 3-( p -iodophenyl)propanoate to afford ( R )- 1 and then the enantioselective hydrolysis of the resultant ester to afford ( S )- 1 .

Lipase-catalyzed transesterification of 2-phenyl-1-propanol with vinyl esters having aromatic ring in acyl moiety

Abstract The highly enantioselective transesterification of 2-phenyl-1-propanol, which has not been efficiently resolved by lipase-catalyzed reactions, was attained by using either vinyl 3-( p -tolyl)propanoate or vinyl 3-(2-naphthyl)propanoate as the acyl donor.

Asymmetric synthesis of 2-substituted chroman-4-ones using lipase-catalyzed kinetic resolutions

2-Methylchroman-4-one and 2-phenylchroman-4-one were synthesized in optically active form. Their chiral intermediates were obtained via lipase-catalyzed enantioselective reactions.

Enzymatic resolution of 2-phenyl-1-propanol by enantioselective hydrolysis of its ester having a bulky group in an acyl moiety

Enzymatic resolution of 2-phenyl-1-propanol, enantiomeric ratios of which were recently improved up to 31 and 41 with lipase PS and PPL, respectively, by transesterification using vinyl 3-phenylpropanoate, was more excellently attained by PPL-catalyzed hydrolysis of its ester of 3-phenylpropanoic acid in 107 of E value.

Practical production of (S)-1,2-propanediol and its derivative through baker's yeast-mediated reduction.

The enantiomeric excess (ee) of (S)-1,2-propanediol produced by bakers yeast-mediated reduction of 1-acetoxy-2-propanone was improved to 96% ee by a fed-batch operation of the substrate. A similar reduction of 1-benzoyloxy-2-propanone stopped because of the inhibition toward the enzymes for NADPH regeneration by the reduction product. The inhibition was prevented using resin that adsorbs the product from the reaction mixture, and 70 g/l substrate was reduced yielding (S)-1-benzoyloxy-2-propanol at > 99% ee.

Effect of aeration conditions on aldehyde dehydrogenase activity in yeast cultivation

The culture conditions under aeration affected the reduction ability of yeast strains using ethanol as an energy source. This was caused by changes in the aldehyde dehydrogenase (ALDH) activity, which was demonstrated by measuring the ALDH activities of Saccharomyces cerevisiae and Kloeckera magna. The ALDH activities of these yeasts were maximum at an oxygen absorption rate of 18 mmol/h/l.

Asymmetric synthesis of chiral 2-fluorinated 1,3-propanediols and its application to the preparation of monofluorinated chiral synthon

Abstract Asymmetric synthesis of optically active 2-fluorinated 1,3-propanediols was achieved by enzymatical resolution and applied to obtain a chiral monofluorinated synthon for lignan derivatives.

Binding site of acyl moiety in ester hydrolysis by Candida rugosa lipase

Abstract The sizes of the large, medium, and small substituent recognition sites (L, M, and S pockets, respectively) in Candida rugosa lipase (CRL) were roughly estimated by measuring the specific hydrolytic activity against several p-nitrophenyl esters. These relative sizes were assessed as L pocket>phenyl, ethyl>M pocket>methyl>S pocket>hydrogen. The hydrolysis of a series of p-nitrophenyl esters of ω-substituted fatty acids was also examined. In this series, p-nitrophenyl esters having one methylene between the ester–carbonyl carbon and cyclohexyl, phenyl, or isopropyl moiety largely demonstrated decreases in hydrolytic activity.

Enzymatic resolution of 2-fluoro-2-arylacetic acid derivatives

Abstract Optical resolutions of 2-fluoro-2-arylacetic acids, ArC*FRCOOH (R=CN, H, and Me), were performed by enantioselective hydrolysis of the corresponding esters using Candida rugosa lipase (CRL). The enantioselectivity of commercial CRL toward the esters was greatly improved when commercial CRL was treated with 2-propanol solution. In the enantioselective hydrolysis of these esters, as represented by ArC*SMCOOR (S and M are small and medium substituents, respectively), the active site of the 2-propanol-treated CRL recognized fluorine as S in both PhCF(CH3)COOR and p-TolCF(CN)COOR but recognized fluorine as M in PhCHFCOOR.