- Chemoenzymatic Synthesis of the Intermediates in the Peppermint Monoterpenoid Biosynthetic Pathway
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A chemoenzymatic approach providing access to all four intermediates in the peppermint biosynthetic pathway between limonene and menthone/isomenthone, including noncommercially available intermediates (-)-trans-isopiperitenol (2), (-)-isopiperitenone (3), and (+)-cis-isopulegone (4), is described. Oxidation of (+)-isopulegol (13) followed by enolate selenation and oxidative elimination steps provides (-)-isopiperitenone (3). A chemical reduction and separation route from (3) provides both native (-)-trans-isopiperitenol (2) and isomer (-)-cis-isopiperitenol (18), while enzymatic conjugate reduction of (-)-isopiperitenone (3) with IPR [(-)-isopiperitenone reductase)] provides (+)-cis-isopulegone (4). This undergoes facile base-mediated chemical epimerization to (+)-pulegone (5), which is subsequently shown to be a substrate for NtDBR (Nicotiana tabacum double-bond reductase) to afford (-)-menthone (7) and (+)-isomenthone (8).
- Cheallaigh, Aisling Ní,Mansell, David J.,Toogood, Helen S.,Tait, Shirley,Lygidakis, Antonios,Scrutton, Nigel S.,Gardiner, John M.
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p. 1546 - 1552
(2018/08/04)
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- Biosynthesis of menthofuran in Mentha x piperita: Stereoselective and mechanistic studies
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Mentha x piperita shoot tips and first leaf pair were fed with aqueous solutions of [2H2]- and [2H2]/[18O]-labeled pulegone. The essential oil was analyzed by solid phase microextraction and enantioselective multidimensional gas chromatography/mass spectrometry. After feeding experiments with labeled pulegone racemate, both labeled (S)-menthofuran and (R)-menthofuran were detectable simultaneously together with genuine (R)- menthofuran. It could be shown that both labeled pulegone enantiomers are converted by Mentha x piperita to the corresponding labeled menthofuran enantiomers, favoring the labeled analogue of the nongenuine (S)-pulegone. The oxygen in menthofuran is introduced by enzymatic oxidation of pulegone, as concluded from feeding experiments with mixed labeled [2H2]/[18O]pulegone.
- Fuchs, Sabine,Zinn, Silvia,Beck, Thomas,Mosandl, Armin
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p. 4100 - 4105
(2007/10/03)
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- Large-Scale Preparation of Pure (+)-(1S,2R,5S)-5-Methyl-2-(1-methyl-1-phenylethyl)cyclohexanol
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A procedure is described for the preparation of (S)-(-)pulegone, (-)-1, starting from (S)-(-)citronellol, (-)-6, in a preparative scale.Compound (-)-1 can easily be converted into (+)-(1S,2R,5S)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexanol: (+)-2 by a procedure described in literature, which was simplified essentially.Now (+)-2 is accessible in larger amounts and thus is available as an efficient chiral auxiliary in stoichiometric asymmetric syntheses.
- Buschmann, Helmut,Scharf, Hans-Dieter
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p. 827 - 830
(2007/10/02)
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