- Stereoselective synthesis and application of tridentate aminodiols derived from (+)-pulegone
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A library of tridentate aminodiols, derived from naturally occurring (R)-(+)-pulegone, was synthesized and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The reduction of pulegone furnished pulegol, which was transformed into
- Gonda, Tímea,Szakonyi, Zsolt,Csámpai, Antal,Haukka, Matti,Fül?p, Ferenc
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- Eco-friendly stereoselective reduction of α,β-unsaturated carbonyl compounds by Er(OTf)3/NaBH4 in 2-MeTHF
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An operationally simple and environmentally benign catalytic procedure has been developed to selectively reduce different α,β-unsaturated ketones. The corresponding allylic alcohols are obtained with high chemo- and diastereoselectivity using Er(OTf)3 and NaBH4 in 2-MeTHF. This protocol reduces the amount of catalyst and NaBH4 needed, compared to classical procedures and the stages of extraction/purification are carried out in aqueous solutions avoiding the use of toxic solvents. Taking into account that Er(OTf)3 can be considered even less toxic than table salt and the 'greenness' of 2-MeTHF as a solvent, the system Er(OTf)3/2-MeTHF can be proposed as a cheap, efficient, and environmentally sustainable reduction system for the synthesis of allylic alcohols.
- Nardi, Monica,Sindona, Giovanni,Costanzo, Paola,Oliverio, Manuela,Procopio, Antonio
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p. 1132 - 1135
(2015/02/19)
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- Synthesis of saturated benzodioxepinone analogues: Insight into the importance of the aromatic ring binding motif for marine odorants
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As part of our research exploring the influence of molecular variations of Calone 1951 on marine fragrance performance, we report the synthesis, crystal structures, and olfactory analysis of the first saturated benzodioxepinone analogues. By su
- Plummer, Christopher M.,Gericke, Robert,Kraft, Philip,Raynor, Aaron,Froese, Jordan,Hudlick, Tom,Rook, Trevor J.,Jones, Oliver A. H.,Hügel, Helmut M.
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p. 486 - 495
(2015/01/30)
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- CuH-catalyzed enantioselective 1,2-reductions of α,β-unsaturated ketones
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The first study on a general technology for arriving at valued nonracemic allylic alcohols using asymmetric ligand-accelerated catalysis by copper hydride is described.
- Moser, Ralph,Boskovia, Zarko V.,Crowe, Christopher S.,Lipshutz, Bruce H.
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supporting information; experimental part
p. 7852 - 7853
(2010/08/04)
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- Asymmetric hydrogenation of heteroaromatic ketones and cyclic and acyclic enones mediated by Cu(I)-chiral diphosphine catalysts
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Copper(I)-catalyzed asymmetric hydrogenation of heteroaromatic ketones, cyclic and acyclic enones is reported. The choice of the chiral diphosphine ligand highly influenced enantiose-lectivity as well as chemoselectivity. Highly enantioselective hydrogenation of ortho-substituted heteroaromatic ketones was achieved using BDPP as the ligand. In the 1,2-selective hydrogenation of acylic enone, SEGPHOS gave higher enantioselectivity than BDPP. On the other hand, the bulky ligand DTBM-SEGPHOS had a 1,4-selective nature, leading to the first highly 1,4-selective and enantioselective hydrogenation of cyclic enones.
- Shimizu, Hideo,Nagano, Takuto,Sayo, Noboru,Saito, Takao,Ohshima, Takashi,Mashima, Kazushi
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scheme or table
p. 3143 - 3146
(2010/03/24)
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- Highly enantio- and s-trans C=C bond selective catalytic hydrogenation of cyclic enones: Alternative synthesis of (-)-menthol
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A highly enantioselective catalytic hydrogenation of cyclic enones was achieved by using the combination of a cationic Rh1 complex, (S)-5,5′-bis{di(3,5-di-tert-butyl-4-methoxyphenylphosphino)}-4, 4′-bi-1,3-benzodioxole (DTBM-SEGPHOS), and (CH2CH 2PPh3Br)2. The presence of an s-cis C=C bond isopropylidene moiety on the cyclic enone influenced the enantioselectivity of the hydrogenation. Thus, the hydrogenation of 3-alkyl-6-isopropylidene-2- cyclohexen-1-one, which contains both s-cis and s-trans enones, proceeded in excellent enantioselectivity (up to 98% ee). To obtain high enantio- and s-trans selectivities, the addition of a halogen source to the cationic Rh complex was the essential step. With the key step of the s-trans selective asymmetric hydrogenation of piperitenone, we demonstrated a new synthetic method for optically pure (-)-menthol via three atom-economical hydrogenations. Moreover, we found that the complete s-trans and s-cis C=C bond selective reactions were also realized by the proper choice of both the chiral ligands and halides.
- Ohshima, Takashi,Tadaoka, Hiroshi,Hori, Kiyoto,Sayo, Noboru,Mashima, Kazushi
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experimental part
p. 2060 - 2066
(2009/04/07)
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- Bioreduction of aldehydes and ketones using Manihot species
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Biocatalysis constitutes an important tool in organic synthesis, especially for the preparation of chiral molecules of biological interest. A series of aliphatic and aromatic aldehydes and two ketones were reduced using plant cell preparations from Manihot esculenta and Manihot dulcis roots. The reduced products were typically obtained in excellent yields (80-96%), and with excellent enantiomeric excess (94-98%), except for vanillin. Esters, a nitrile, and an amide were also examined, but were not reduced. Preliminary conversion rate studies are reported. This is the first attempt to perform the biotransformation of carbonyl compounds using Manihot species.
- Machado, Luciana L.,Souza, Joao Sammy N.,de Mattos, Marcos Carlos,Sakata, Solange K.,Cordell, Geoffrey A.,Lemos, Telma L.G.
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p. 1637 - 1643
(2008/02/11)
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- Lactones. 21. Synthesis and Odoriferous Properties of Lactones with the p-Menthane System
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Starting from (R)-(+)- and (S)-(-)-pulegone, enantiomeric pairs of esters and lactones with the p-menthane system were obtained. The Claisen rearrangement of allylic alcohols and iodolactonization of γ,δ -unsaturated acids were the key steps of syntheses
- Dams, Iwona,Bialonska, Agata,Ciunik, Zbigniew,Wawrzenczyk, Czeslaw
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p. 1630 - 1634
(2007/10/03)
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- Synthesis of terpenoid lactones with the p-menthane system
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Starting from (R)-(+)- and (S)-(-)-pulegone enantiomeric pairs of hydroxy lactones and keto lactones were obtained by Claisen rearrangement of cis-pulegols and lactonization of epoxy esters. The hydroxy lactones were reduced with Li-AlH4 in ord
- Dams, Iwona,Bialonska, Agata,Ciunik, Zbigniew,Wawrzenczyk, Czeslaw
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p. 2662 - 2668
(2007/10/03)
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- Lipase-catalyzed resolution of p-menthan-3-ols monoterpenes: Preparation of the enantiomer-enriched forms of menthol, isopulegol, trans- and cis-piperitol, and cis-isopiperitenol
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A study on the enzymic resolution of the most common p-menthan-3-ol monoterpene isomers is described. Enantioenriched alcohols 1, 5, 10, 11 and 12 are obtained by means of the lipase-mediated kinetic acetylation of the corresponding racemic materials. The stereochemical aspects of the enzymic process have been investigated. We found that the structural features of the starting p-menthan-3-ol as well as the kind of lipase used, impacted strongly on the enantioselectivity of the resolution. The potentialities of this approach for preparative purposes are discussed.
- Serra, Stefano,Brenna, Elisabetta,Fuganti, Claudio,Maggioni, Francesco
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p. 3313 - 3319
(2007/10/03)
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- Method for producing 1-menthol
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Provided is a method for the production of 1-menthol, which comprises hydrogenation of piperitenone with a transition metal complex of a specified optically active phosphine to produce pulegone, hydrogenation of the obtained pulegone with a ruthenium-phosphine-amine complex in the presence of base to obtain pulegol, and further hydrogenation of the pulegol with a transition metal catalyst.
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- Asymmetric hydrogenation of cyclic α,β-unsaturated ketones to chiral allylic alcohols
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The Ru(II)-BINAP-1,2-diphenylethylenediamine combined catalyst system effects asymmetric hydrogenation of certain cyclic enones in 2-propanol containing KOH with a substrate/catalyst molar ratio of 250 to 2500. The hydrogenation occurs selectively at the C=O function with excellent enantio- or diastereoselectivity.
- Ohkuma, Takeshi,Ikehira, Hideyuki,Ikariya, Takao,Noyori, Ryoji
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p. 467 - 468
(2007/10/03)
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- Aminoborohydrides. 4. The Synthesis and Characterization of Lithium Aminoborohydrides: A New Class of Powerful, Selective, Air-Stable Reducing Agents
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Lithium aminoborohydrides (LiABH3) are a new class of powerful yet selective reducing agents that reproduce, in air, virtually all of the transformations for which lithium aluminum hydrides is now used.LiABH3's can be readily prepared as solids or generated in situ, are nonpyrophoric, and liberate hydrogen only slowly with protic solvents above pH 4.LiABH3's can be handled in dry air as easily as sodium borohydride and retain their chemical activity for at least 6 month when stored under nitrogen or dry air at 25 deg C.LiABH3's can be synthesized from any primary or secondary amine, thus allowing control of the steric and electronic environment of these reagents.
- Fisher, Gary B.,Fuller, Joseph C.,Harrison, John,Alvarez, Salvador G.,Burkhardt, Elizabeth R.,et al.
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p. 6378 - 6385
(2007/10/02)
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- Diisopropoxytitanium(III) Tetrahydroborate: A Highly Useful Reagent for the Remarkably Selective 1,2-Reduction of α,β-Unsaturated Carbonyl Compounds
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Diisopropoxytitanium(III) tetrahydroborate formed by the reaction of diisopropoxytitanium dichloride and benzyltriethylammonium borohydride (1:2) reacts with a variety of α,β-unsaturated carbonyl compounds in dichloromethane (-20 deg C) very readily to yield exclusively the corresponding allylic alcohols in excellent yields.
- Ravikumar, K. S.,Baskaran, Sundarababu,Chandrasekaran, Srinivasan
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p. 5981 - 5982
(2007/10/02)
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- Total Synthesis of 1233A
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The total synthesis of the HMG-CoA synthase inhibitor 1233A (1), starting from either (R)-pulegone (6) or diketo ester 12, is described.The key transformations included the diastereoselective rearrangements of allylic ethers 9 and 19 to alcohols 10
- Wovkulich, P. M.,Shankaran, K.,Kiegiel, J.,Uskokovic, M. R.
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p. 832 - 839
(2007/10/02)
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- The Constituents of Schizonepeta tenuifolia BRIQ. II. Structure of a New Monoterpene Glucoside, Schizonepetoside C
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Besides the three known flavonoid glucosides, a new monoterpene glucoside named schizonepetoside C (3) was isolated from the spikes of Schizonepeta tenuifolia BRIQ. (Labiatae), as an amorphous powder.The structure of 3 was established as (1S,4E)-9-O-β-D-g
- Kubo, Masayoshi,Sasaki, Hiroshi,Endo, Tohru,Taguchi, Heihachiro,Yosioka, Itiro
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p. 3097 - 3101
(2007/10/02)
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- ALKYL METAL ASYMMETRIC REDUCTION. 11. THE REACTION OF α,β-UNSATURATED KETONES WITH β-BRANCHED TRIALKYLALUMINIUM COMPOUNDS.
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The reduction of a series of α,β-unsaturated ketones has been studied under various experimental conditions, by using β-branched trialkylalanes.Asymmetric induction phenomena are observed when optically active trialkylalanes are used.
- Giacomelli, Giampaolo,Caporuso, Anna Maria,Lardicci, Luciano
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p. 3663 - 3666
(2007/10/02)
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- Lanthanoids in Organic Synthesis. 6. The Reduction of α-Enones by Sodium Borohydride in the Presence of Lanthanoid Chlorides: Synthetic and Mechanistic Aspects
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Lanthanoid chlorides (LnCl3) are efficient catalysts for the regioselective 1,2-reduction of α-enones by NaBH4 in methanol solution.Optimal conditions of this reaction have been determined.A mechanistic interpretation depicting the role of the Ln3+ ions is given.The major effect of Ln3+ is the catalysis of BH4- decomposition by the hydroxylic solvent to afford alkoxyborohydrides, which may be responsible for the observed regioselectivity.The stereoselectivity of the process is also modified by the presence of the Ln3+ ions, in that axial attack of cyclohexanone systems is enhanced.
- Gemal, Andre L.,Luche, Jean-Louis
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p. 5454 - 5459
(2007/10/02)
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