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Hydroxy Ketones (hydroxy + ketone)
Selected AbstractsBaker's Yeast Reduction of ,-Hydroxy KetonesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2010Daniela Acetti Abstract Reduction of ,-hydroxy ketones to the corresponding 1,3-diols by baker's yeast was investigated, in order to develop methods for simultaneous control over the configurations of multiple stereogenic centres. The reactions were found to be enantiospecific and generally characterised by good diastereoselectivity. Substrates with a substituent at the carbon atom in the , position were also considered. When the substituent at the ,-carbon atom was part of a ring, higher selectivity was observed. [source] Promiscuous Substrate Binding Explains the Enzymatic Stereo- and Regiocontrolled Synthesis of Enantiopure Hydroxy Ketones and DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Marcela Kurina-Sanz Abstract Regio- and stereoselective reductions of several diketones to afford enantiopure hydroxy ketones or diols were accomplished using isolated alcohol dehydrogenases (ADHs). Results could be rationalised taking into account different (promiscuous) substrate-binding modes in the active site of the enzyme. Furthermore, interesting natural cyclic diketones were also reduced with high regio- and stereoselectivity. Some of the 1,2- and 1,3-diketones used in this study were reduced by employing a low excess of the hydrogen donor (2-propanol) due to the quasi-irreversibility of these ADH-catalysed processes. Thus, using lower quantities of co-substrate, scale-up could be easily achieved. [source] Mixed Aromatic Acyloin Condensations with Recombinant Benzaldehyde Lyase: Synthesis of ,-Hydroxydihydrochalcones and Related ,-Hydroxy KetonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Monica Sanchez-Gonzalez Abstract Recombinant benzaldehyde lyase (BAL), expressed and purified from E.,coli strain JM-109, was used to catalyze the condensation of a series of methoxybenzaldehydes and phenylacetaldehyde in the synthesis of ,-(R)-hydroxydihydrochalcones. Enantiomerically pure 1-hydroxy-1,3-diphenylpropan-2-ones and o -anisoin were also obtained as products of the BAL reaction. The R absolute configurations of chiral centers were determined by CD spectroscopy. ,-(R)-Hydroxydihydrochalcones and 1-hydroxy-1,3-diphenylpropan-2-ones are valuable synthons for chemoenzymatic syntheses of flavonoids. This is the first synthesis of ,-(R)-hydroxydihydrochalcones by a microbial enzyme. [source] ChemInform Abstract: Efficient Synthesis of ,-Hydroxy Ketones from Allylic Alcohols by Catalytic Formation of Ruthenium Enolates.CHEMINFORM, Issue 14 2009Agnieszka Bartoszewicz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Diketones and ,-Hydroxy Ketones from Methyl Ketones and ,,,-Diols by an [IrCl(cod)]2/PPh3/KOH System.CHEMINFORM, Issue 39 2008Kensaku Maeda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] High Chelation Control of Three Contiguous Stereogenic Centers in the Reformatsky Reactions of Indium Enolates with ,-Hydroxy Ketones: Unexpected Stereochemistry of Lactone Formation.CHEMINFORM, Issue 46 2006Srinivasarao Arulananda Babu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Iodine and Iodic Acid: An Efficient Reagent Combination for Iodination of Aryl Hydroxy Ketones.CHEMINFORM, Issue 3 2006Bhagwan R. Patil No abstract is available for this article. [source] Hydrazine Hydrate Induced Reductive Cleavage of ,,,-Epoxy Ketones: An Efficient Procedure for the Preparation of ,-Hydroxy Ketones.CHEMINFORM, Issue 22 2005Jorge A. R. Salvador Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Synthesis of Cyclic Hydroxy Ketones Derived from Enol Ethers via Sharpless Asymmetric Dihydroxylation.CHEMINFORM, Issue 9 2004A Study in the Correlation of the Enol Ether Chain Length, Enantioselectivity. Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Gallium Mediated Barbier Reactions of 1,2-Diones: A Facile Synthesis of ,-Hydroxy Ketones.CHEMINFORM, Issue 23 2002Vijay Nair Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Enantioselective Synthesis of Hydroxy Ketones Through Cleavage and Formation of Acyloin Linkage.CHEMINFORM, Issue 38 2001C Bond Cleavage., Enzymatic Kinetic Resolution via C Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Highly Stereoselective Addition to Alkoxy or Hydroxy Ketones Using an ,-Stannyl Ester,Stannous Chloride System in a Chelation-Controlled Manner.CHEMINFORM, Issue 19 2001Makoto Yasuda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Efficient Synthesis of ,-Hydroxy Ketones from Allylic Alcohols by Catalytic Formation of Ruthenium EnolatesCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2008Agnieszka Bartoszewicz The most efficient Ru-catalyzed isomerization,aldol reaction from allylic alcohols has been achieved by using [,5 -(Ph5Cp)Ru(CO)2Cl] as the catalyst. The bulky pentaphenylcyclopentadienyl ligand on the ruthenium atom prevents protonation at the oxygen of the Ru,enolate intermediate and completely suppresses the formation of unwanted ketone byproducts (see scheme). The domino transformation is as good as it can be: aldols are obtained in quantitative yields at ambient temperature. [source] Synthesis of 2-Azabicyclo[3.2.2]nonane-Derived Monosaccharide Mimics and Their Evaluation as Glycosidase InhibitorsHELVETICA CHIMICA ACTA, Issue 3 2006Stephan Buser Abstract The racemic 2-azabicyclo[3.2.2]nonanes 5 and 18 were synthesized and tested as , -glycosidase inhibitors. The intramolecular Diels,Alder reaction of the masked o -benzoquinone generated from 2-(allyloxy)phenol (6) gave the , -keto acetal 7 which was reduced with SmI2 to the hydroxy ketone 8. Dihydroxylation, isopropylidenation (,,12), and Beckmann rearrangement provided lactam 15. N -Benzylation of this lactam, reduction to the amine 17, and deprotection provided the amino triol 19 which was debenzylated to the secondary amine 5. Both 5 and 19 proved weak inhibitors of snail , -mannosidase (IC50,>,10,mM), Caldocellum saccharolyticum , -glucosidase (IC50,>,10,mM), sweet almond , -glucosidase (IC50,>,10,mM), yeast , -glucosidase (5: IC50,>,10,mM; 19: IC50,=,1.2,mM), and Jack bean , -mannosidase (no inhibition detected). [source] Synthesis of cis-Hedione® and Methyl Jasmonate via Cascade Baylis,Hillman Reaction and Claisen Ortho Ester RearrangementHELVETICA CHIMICA ACTA, Issue 12 2005Christian Chapuis The exocyclically unsaturated conjugated keto esters 10, obtained via a Claisen ortho ester rearrangement of the allylic hydroxy ketones 9, were either directly hydrogenated or partially isomerized into the endocyclically unsaturated tetrasubstituted didehydrojasmonoid intermediates 14, prior to a more selective hydrogenation with Pd/C in cyclohexane to the disubstituted oxocyclopentaneacetates 15 (Scheme,2). The key intermediates 9 were obtained either by a four-step sequence, including acetal protection/deprotection from enone 1, in the specific case of hydroxy ketone 9a (Scheme,1), or more directly and generally by a Baylis,Hillman reaction from cyclopent-2-en-1-one (16) and the appropriate aldehydes 17 (Scheme,2). The judicious choice of these aldehydes opens versatile modifications for the stereoselective introduction of the partially cis - or epimerized trans -C(2) jasmonoid side chain, while the Baylis,Hillman reaction, catalyzed by chiral [1,1,-binaphthalene]-2,2,-diols (BINOLs) 19 (Scheme,3), may be efficiently conducted in a one-pot cascade fashion including the ortho ester Claisen rearrangement. [source] Woody Pretzels: Spirocycles from Vetiver to Patchouli and Georgywood®CHEMISTRY & BIODIVERSITY, Issue 6 2008Philip Kraft Abstract This review, including new experimental results, is the summary of a talk at the RSC/SCI conference ,flavours & fragrances 2007' in London, Imperial College, 24,26 September, 2007. Though the third dimension of the receptor models of J.,E. Amoore rarely was exceeding 4,Å, the world of woody odorants such as (+)-cedrol (3; cedarwood), (,)-khusimone (4; vetiver), and (,)-patchoulol (5; patchouli) is anything but flat. Any tricyclic skeleton with a zero-bridge contains a spirocyclic ring system determining its 3D structure, so spirocycles (spira, Lat. pretzel) are the fastest access to the third dimension. In the vetiver family, a spirocyclic mimic 9 of (,)-khusimone (4) was first discovered by chance by Büchi in 1976, and also by chance, we obtained another system, 12, with a characteristic vetiver smell by tandem- Rupe,Nazarov reaction of alkyne diols. A 5-Å distance between a quaternary C-atom and a carbonyl group (or alternative HB acceptor) with an , -methyl or methylene branching is proposed to be the key to their vetiver odor. Upon scale-up of one of these odorants, 24, we discovered a very powerful (0.067,ng/l) impurity with a most typical patchouli scent: the spirocyclic, sterically crowded hydroxy ketone 33 , a most unusual structure for a patchouli odorant. Several spirocyclic hydroxy ketone analogs, also with inverted ring systems such as in 70 and 84, provided new insights into the structure,odor correlation of this family. A superposition analysis indicated the carbonyl function of the hydroxy ketone to overlay on the geminal dimethyl motive of (,)-patchoulol. And indeed, the corresponding hydroxy ketone of patchoulol, 59, synthesized in 13 steps from Cyclal C (63), also emanated a patchouli odor. Finally, the synthesis and olfactory properties of twelve rigid spirocyclic analogs, 95,97, 99,102, and 106,110, of Georgywood® (91) are presented that highlight stereochemical requirements for woody odorants and raise doubts about an , -helical binding motive postulated by Hong and Corey. [source] Platinum-Catalyzed Regioselective Formation of ,-Alkoxy Ketones from Internal AlkynesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2010Daxin Yang Abstract A catalytic amount of Zeise's dimer and 15-crown-5 were combined to effectively promote the regioselective formation of ,-alkoxy ketones from 2-(homopropargyloxy)ethanols in dimethoxyethane. The desired products were obtained in 59,98,% yields with up to 17:1 exo/endo regioselectivity. The methodology allows access to ,-hydroxy ketones as an aldol reaction alternative. [source] Baker's Yeast Reduction of ,-Hydroxy KetonesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2010Daniela Acetti Abstract Reduction of ,-hydroxy ketones to the corresponding 1,3-diols by baker's yeast was investigated, in order to develop methods for simultaneous control over the configurations of multiple stereogenic centres. The reactions were found to be enantiospecific and generally characterised by good diastereoselectivity. Substrates with a substituent at the carbon atom in the , position were also considered. When the substituent at the ,-carbon atom was part of a ring, higher selectivity was observed. [source] New Functionalised Hydroxymethyl Ketones from the Mild and Chemoselective KMnO4 Oxidation of Chiral Terminal OlefinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2006Carlo Bonini Abstract Various terminal olefinic compounds are directly converted into the corresponding ,-hydroxy ketones in good yields by potassium permanganate oxidation. The reaction is also highly chemoselective in the presence of differently protected hydroxy groups and can be utilised for the preparation of polyfunctional compounds such as polyols. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] The RuO4 -Catalyzed Ketohydroxylation, Part II:A Regio-, Chemo- and Stereoselectivity StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2005Bernd Plietker Abstract The direct RuO4 -catalyzed ketohydroxylation of olefins is a new and convenient method for the preparation of a wide range of symmetrical and unsymmetrical ,-hydroxy ketones. Since reactions in which two different functional groups are introduced in one step always involve regio-, chemo- and stereoselectivity issues, this paper gives a full account of investigations of various selectivity aspects in the ketohydroxylation. Stereoselectivity issues were examined in the final part of the present report. The Kishi rules, known from OsO4 -catalyzed dihydroxylations, are found to be valid for the RuO4 -catalyzed ketohydroxylation and lead to moderate to good diastereomeric ratios in the oxidation of olefins possessing an allylic center of chirality. Furthermore, competition experiments between different substituted olefins led to a reactivity profile applicable to the prediction of which is the most reactive of different C=C double bonds present in a molecule. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis of (+)-13-Stemarene and (+)-18-Deoxystemarin: Expeditious Preparation of the Key 6- exo -Hydroxybicyclo[2.2.2]octan-2-one, Ethylene DithioacetalHELVETICA CHIMICA ACTA, Issue 4 2008Francesca Leonelli Abstract An expeditious preparation of the 6- exo -hydroxybicyclo[2.2.2]octan-2-one ethylene dithioacetal 2b, a key intermediate in the synthesis of (+)-13-stemarene (4) and (+)-18-deoxystemarin (5) is described. Compound 2b was obtained as the major product by equilibrating the endo rich mixture of 6-hydroxybicyclo[2.2.2]octan-2-one ethylene dithioacetals 2 with TsOH in benzene at reflux, easily available from the corresponding hydroxy ketones 9. The model experiments which preceeded the above transformation, not previously described in the literature, are also presented. [source] Synthesis of cis-Hedione® and Methyl Jasmonate via Cascade Baylis,Hillman Reaction and Claisen Ortho Ester RearrangementHELVETICA CHIMICA ACTA, Issue 12 2005Christian Chapuis The exocyclically unsaturated conjugated keto esters 10, obtained via a Claisen ortho ester rearrangement of the allylic hydroxy ketones 9, were either directly hydrogenated or partially isomerized into the endocyclically unsaturated tetrasubstituted didehydrojasmonoid intermediates 14, prior to a more selective hydrogenation with Pd/C in cyclohexane to the disubstituted oxocyclopentaneacetates 15 (Scheme,2). The key intermediates 9 were obtained either by a four-step sequence, including acetal protection/deprotection from enone 1, in the specific case of hydroxy ketone 9a (Scheme,1), or more directly and generally by a Baylis,Hillman reaction from cyclopent-2-en-1-one (16) and the appropriate aldehydes 17 (Scheme,2). The judicious choice of these aldehydes opens versatile modifications for the stereoselective introduction of the partially cis - or epimerized trans -C(2) jasmonoid side chain, while the Baylis,Hillman reaction, catalyzed by chiral [1,1,-binaphthalene]-2,2,-diols (BINOLs) 19 (Scheme,3), may be efficiently conducted in a one-pot cascade fashion including the ortho ester Claisen rearrangement. [source] Promiscuous Substrate Binding Explains the Enzymatic Stereo- and Regiocontrolled Synthesis of Enantiopure Hydroxy Ketones and DiolsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Marcela Kurina-Sanz Abstract Regio- and stereoselective reductions of several diketones to afford enantiopure hydroxy ketones or diols were accomplished using isolated alcohol dehydrogenases (ADHs). Results could be rationalised taking into account different (promiscuous) substrate-binding modes in the active site of the enzyme. Furthermore, interesting natural cyclic diketones were also reduced with high regio- and stereoselectivity. Some of the 1,2- and 1,3-diketones used in this study were reduced by employing a low excess of the hydrogen donor (2-propanol) due to the quasi-irreversibility of these ADH-catalysed processes. Thus, using lower quantities of co-substrate, scale-up could be easily achieved. [source] Isolation and antimicrobial evaluation of isomeric hydroxy ketones in leaf cuticular waxes of Annona squamosa,PHYTOCHEMICAL ANALYSIS, Issue 1 2007K. Shiva Shanker Abstract A novel natural compound, 11-hydroxy-16-hentriacontanone, has been isolated from the leaf cuticular wax of Annona squamosa along with its known isomer 10-hydroxy-16-hentriacontanone in a ratio of 67:33. This isomeric mixture of hydroxy ketones constituted together 16.5% of the total cuticular waxes. The new compound was characterised using spectral and chromatographic techniques. The major component was found to be 16-hentriacontanone (palmitone), which constituted up to 48% of the total cuticular wax, together with a homologous series of hydrocarbons, fatty aldehydes, fatty alcohols, fatty acids and sterols as minor components. The antimicrobial activity of the isomeric hydroxy ketones was tested against selected Gram-positive and Gram-negative bacterial strains, and also some selected fungal strains, and compared with palmitone. The antibacterial activity of palmitone was significantly higher than that of the isomeric hydroxy ketones, but their antifungal activities were comparable. Copyright © 2006 John Wiley & Sons, Ltd. [source] Diastereo- and Enantioselective Reductive Aldol Reaction with Trichlorosilane Using Chiral Lewis Bases as OrganocatalystsCHEMISTRY - AN ASIAN JOURNAL, Issue 3 2010Masaharu Sugiura Prof. Chiral Lewis base organocatalysts activate trichlorosilane to promote the tandem conjugate reduction/aldol reaction of ,,,-unsaturated ketones with aldehydes to give optically active ,-hydroxy ketones with good to high syn diastereo- and enantioselectivities. The reaction tolerates ,,,-unsaturated aldehydes owing to the chemoselective conjugate reduction of enones in the presence of enals. 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