- Enzyme-mediated preparation of enantiomerically pure p-menthan-3,9-diols and their use for the synthesis of natural p-menthane lactones and ethers
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The diastereoselective preparation of the p-menthane-3,9-diols (±)-12, (±)-13a, (±)-13b, and (±)-18 and the study of their enzymic resolution is described (Scheme 1). The corresponding enantiomer-enriched diols obtained by means of the lipase-mediated kinetic acetylation of the racemic diols are suitable synthetic precursors of many relevant p-menthane monoterpenes. Their usefulness is shown in the preparation of different natural products of this class that are interesting for industrial purposes because of their odor qualities, i.e., of the enantiomeric form of 3-hydroxy-p-menthan-9-oic acid lactone 1, of mintlactone 2, of the 3,9-epoxy-p-menth-1,8(10)-diene 10, and of the pheromone vesperal 11 (Schemes 2 and 3).
- Serra, Stefano,Fuganti, Claudio
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p. 2489 - 2502
(2007/10/03)
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- Synthesis and organoleptic properties of p-menthane lactones
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The stereoselective synthesis and organoleptic properties of p-menthane lactones 7a-h are described. Apart from correcting the published data concerning these compounds, this work has also allowed an unambiguous identification of 7a, 7b and 7g in Italo Mi
- Gaudin, Jean-Marc
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p. 4769 - 4776
(2007/10/03)
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- Isopulegol as a model compound: Metalation and substitution of an allylic position in the presence of an unprotected hydroxy function
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When treated with butyllithium and potassium tert-butoxide for 2 h at 0 °C in hexanes, the unsaturated monoterpenic alcohol isopulegol is simultaneously deprotonated at the hydroxy function and the allylic methyl group. The metaloxy allylmetal species thu
- Schlosser, Manfred,Kotthaus, Martina
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p. 459 - 462
(2007/10/03)
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- TOTAL SYNTHESIS OF VARIOUS ELEMANOLIDES
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Starting with a suitable substituted divinyl cyclohexanone, eleven naturally occurring 12.8-elemanolides bearing exo-methylene or methyl groups at C-11 and differing in substitution as well as in relative configuration, have been synthesized in racemic form.An approach to elemanolides with additional oxygen functionalities is principally possible by modification of the basic concept.Methods for the oxidative generation of terpenoid exo-methylene lactone and furan units are exemplified by synthesis of menthofuran and the p-menthenolides from isopulegols.
- Friedrich, Dirk,Bohlmann, Ferdinand
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p. 1369 - 1392
(2007/10/02)
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- TOTAL SYNTHESIS OF p-MENTHENOLIDES
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A general approach to both cis- and trans-fused α-methylene γ-butyrolactones has been developed.This includes a new, mild method for the oxidation of α,β-unsaturated aldehydes.In addition, a new method to couple trans-α-methylene hydroxy acids into trans-lactones or, alternatively, cis-lactones has been developed.This strategy has been applied to the total synthesis of both cis- and trans-p-menthenolide, prepared in 35percent (trans) and 21percent (cis) overall yields from isopulegol.
- Bal, Balkrishna S.,Pinnick, Harold W.
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p. 2091 - 2104
(2007/10/02)
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