55449-44-0Relevant articles and documents
Enantiomeric ratios of 2-methylbutanoic acid and its methyl ester: Elucidation of novel biogenetic pathways towards (R)-methyl 2-methylbutanoate in a beverage fermented with shiitake
Zhang, Yanyan,Fraatz, Marco Alexander,Birk, Florian,Rigling, Marina,Hammer, Andreas,Zorn, Holger
, p. 475 - 482 (2018)
Up to 35% of (R)-methyl 2-methylbutanoate (M2MB) was observed in a beverage fermented with shiitake. As M2MB naturally occurs typically in high excesses of the (S)-enantiomer, the origin of the (R)-ester was elucidated by stable isotope labeled precursor-feeding studies. (R)-2-Methylbutanoic acid was identified as the main precursor in the substrate wort. Trace amounts of (R)-M2MB were produced by transformation of unsaturated secondary metabolites (tiglic aldehyde and tiglic acid) derived from L-isoleucine. Surprisingly, shiitake esterified (R)-2-methylbutanoic acid faster to (R)-M2MB than the corresponding (S)-enantiomer. Concurrently, spontaneous non-enantioselective degradation of M2MB occurred in shiitake. This explains diverse enantiomeric ratios of M2MB and different enantiomeric ratios of 2-methylbutanoic acid and M2MB in the beverage. As the odor threshold values of (R)-and (S)-M2MB differ significantly, these findings are of high relevance for the overall flavor of the fermented beverage and elucidate the discrepancy of enantiomeric ratios of 2-alkyl-branched acids and esters reported in nature.
Heterogeneous catalytic hydrogenation of olefinic substrates by poly-NAP
Ter Halle, Rob,Schulz, Emmanuelle,Spagnol, Michel,Lemaire, Marc
, p. 3323 - 3326 (2007/10/03)
With our previously described poly-NAP, various olefinic substrates were reduced with selectivities comparable to those obtained by BINAP. For substrates which contained a methyl ester, the selectivities were higher than those observed for their carboxylic acid analogues. (C) 2000 Elsevier Science Ltd.