Stereoisomere Aromastoffe XIX: Asymmetrische Reduktion von 4(5)-Oxocarbonsäuren mit Bäckerhefe / Asymmetric Reduction of 4(5)-Oxocarboxylic Acids by Baker's Yeast

Abstract

In stitu t für P harm azie und L ebensm ittelchem ie d e r U niversität W ürzburg, A m H u b lan d , D-8700 W ürzburg, B u ndesrepublik D eutschland Z . N aturforsch. 42c, 1 159 -1 1 6 4 (1987); received Ju n e 22, 1987 O xocarboxylic A cids. Y east A sym m etrie reduction of 4(5)-oxocarboxylic acids (esters) by b a k e r's yeast and cyclization in acidic m edia yields optically active y(6)-lactones. T he evaluation of th eir chirality and optical pu rity was carried out by H P L C (H R G C ) analysis o f the c o rresp o n d in g l,4 (1 .5 )-d io ls via diastereo m eric esters with (/?)-M osher acid (M T P A ) and (S)-O -acyllactic acids respectively. By in creasing the 4(5) alkyl side chain 4 R (5 R ) co nfigurated y (6 )-lacto n es w ith high ee-values are g e n era te d . EinleitungHPLC (präp.): LEW A Pumpe (max. Fördermen-

Stereoisomeric flavor compounds. 20. Structure and properties of .gamma.-lactone enantiomers

“…Asymmetric reduction of 4-oxoalkanoic acids by baker's yeast predominantly yields (4R)-configurated 7-lactones with increasing size of the alkyl side chain. Within the series 7-hexalactone to 7-dodecalactone, the yeast reduction product is nearly optically pure and (4ff)-configurated (Gessner et al, 1987).…”

“…(it) Reductive cleavage of y-lactones with LiAlH4 yields chiral 1,4-diols. Their stereodifferentiation via diaste- reomeric diesters with (fi)-a-methoxy-a-(trifluoromethyl)phenylacetic acid by HPLC (Gessner et al, 1987) and via (S)-O-acyllactic acid esters (Deger et al, 1988) are well documented. The -lactones 1-10 and 1'-10' are proved to be optically pure by these methods (ee > 99.8%).…”

“…1 Part 19: Gessner et al (1987). Dedicated to Professor Dr. C. H. Brieskorn, Würzburg, FRG, on the occasion of his 75th birthday.…”

Yeast‐Mediated Stereoselective Synthesis

“…From the reduction of γ-and δ-keto esters the corresponding γ-or δ-lactones (Figure 21.20; transformation of starting material 64 to yield the corresponding lactones 65 and 66, respectively) were obtained [298][299][300][301][302][303][304][305]. A two-step mechanism has been suggested for this transformation, and it was assumed that first the ester was hydrolyzed by a nonspecific esterase followed by a reductive step of either the acid or of a corresponding CoA-thioester intermediate.…”

Volatile components of bittermelon

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7-dodecalactone, the yeast reduction product is nearly optically pure and (4ff)-configurated (Gessner et al, 1987).For the case of 3,4-dimethyl 7-lactone the odor activity depends on geometric as well as optical isomerism (Table VI). The (4S)-configurated isomer is much more intense as the (4f?

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