- A convenient synthesis of amino acid-derived precursors to the important wine aroma 3-sulfanylhexan-1-ol (3SH)
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A convenient, straightforward synthesis of the important amino acid-derived aroma precursors, 3-S-cysteinylhexan-1-ol (Cys-3SH) and 3-S-glutathionylhexan-1-ol (GSH-3SH) from commercially available butan-1-ol is reported. The versatility of this approach to include deuterium labelling is also demonstrated.
- Barker, David,Duhamel, Nina,Fedrizzi, Bruno,Jelley, Rebecca E.
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- Synthesis of isotopically labelled thiol volatiles and cysteine conjugates for quantification of Sauvignon Blanc wine
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The thiols 4-mercapto-4-methylpentan-2-ol (4MMPOH), 3-mercaptohexan-1-ol (3MH), and 3-mercaptohexyl acetate (3MHA), which contribute to the aroma profile of Sauvignon Blanc, as well as other varieties of wine, have been synthesized with deuterium labels. The cysteinylated precursors of the thiols, 4-(4-methylpentan-2-one)-L-cysteine (4MMP-cys) and 4-(4-methylpentan-2-ol)-L- cysteine (4MMPOH-cys), found in grape must were also synthesized with deuterium labels. These deuterated compounds provide useful internal standards for the quantification of these thiols in wine using LCMS. Copyright
- Hebditch, Katherine R.,Nicolau, Laura,Brimble, Margaret A.
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- Synthesis of alkyl sulfonic acid aldehydes and alcohols, putative precursors to important wine aroma thiols
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The synthesis of the low molecular weight sulfonic acids, 2-methyl-4-oxopentane-2-sulfonic acid, 1-hydroxyhexane-3-sulfonic acid, 1-oxohexane-3-sulfonic acid and 1-hydroxyhexane-1,3-disulfonic acid from trans-2-hexenal and ethyl hex-2-enoate is reported. These sulfonic acids are putative precursors to the important wine aroma thiols, 3-mercaptohexan-1-ol, 3-mercaptohexyl acetate and 4-mercapto-4-methylpentan-2-one.
- Duhamel, Nina,Piano, Federico,Davidson, Samuel J.,Larcher, Roberto,Fedrizzi, Bruno,Barker, David
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Read Online
- First synthesis of 3-S-glutathionylhexanal-d8 and its bisulfite adduct
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3-Sulfanylhexan-1-ol (3SH) is an impact odorant of white wines, imparting tropical fruit aromas. A reliable synthetic pathway to 3-S-glutathionylhexanal (glut-3SH-al), a precursor to 3SH that has not been intensively studied, was developed starting from 1-butanol. Application of this synthesis to 1-butanol-d10, conserved eight deuteriums, producing glut-3SH-al-d8, which can be used as an internal standard for future work on the occurrence and evolution of glut-3SH-al in wine systems. Additionally, both glut-3SH-SO3 and glut-3SH-SO3-d8 were synthesised from the corresponding aldehyde, enabling further study of the role of these bisulfite adducts in 3SH biogenesis.
- Muhl, Jennifer R.,Pilkington, Lisa I.,Deed, Rebecca C.
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supporting information
(2020/06/17)
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- Copper-Catalyzed Azide–Ynamide Cyclization to Generate α-Imino Copper Carbenes: Divergent and Enantioselective Access to Polycyclic N-Heterocycles
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Here an efficient copper-catalyzed cascade cyclization of azide-ynamides via α-imino copper carbene intermediates is reported, representing the first generation of α-imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N-heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities. Moreover, an asymmetric azide–ynamide cyclization has been achieved with high enantioselectivities (up to 98:2 e.r.) by employing BOX-Cu complexes as chiral catalysts. Thus, this protocol constitutes the first example of an asymmetric azide–alkyne cyclization. The proposed mechanistic rationale for this cascade cyclization is further supported by theoretical calculations.
- Chen, Yang-Bo,Deng, Chao,Liu, Rai-Shung,Liu, Xin,Luo, Chen,Wang, Ze-Shu,Ye, Long-Wu,Zhai, Tong-Yi,Zhang, Yi-Ping
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supporting information
p. 17984 - 17990
(2020/08/21)
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- Visible-Light-Promoted Intramolecular α-Allylation of Aldehydes in the Absence of Sacrificial Hydrogen Acceptors
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We report herein an unprecedented protocol for radical cyclization of aldehydes with pendant alkenes via synergistic photoredox, cobaloxime, and amine catalysis. The transformation was achieved in the absence of external oxidants, providing a variety of 5-, 6-, and 7-membered ring products with alkene transposition in satisfactory yields. The reaction exhibits wide functional group compatibility and occurs under mild conditions with extrusion of H2.
- Liu, Feng,Liu, Jia-Li,tu, Jia-Lin
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supporting information
p. 7369 - 7372
(2020/10/05)
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- Oxidative esterification of aliphatic aldehydes and alcohols with ethanol over gold nanoparticle catalysts in batch and continuous flow reactors
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Selective esterification of aliphatic aldehydes and alcohols with ethanol in the absence of a base is a more difficult reaction than that with methanol. Gold nanoparticles on ZnO were found to catalyze the oxidative esterification of octanal to ethyl octanoate with high selectivity. In addition, it was found that Au/ZnO was the most effective catalyst for yielding the desired ethyl ester without a base by direct esterification of 1-octanol with ethanol. As far as we know, this is the first report on oxidative esterification to give aliphatic ethyl esters from less reactive aliphatic alcohols and aldehydes without a base. The optimal size of gold NPs ranged from 2 to 6 nm and the presence of Au(0) was indispensable for this reaction. Au/ZnO exhibited the highest catalytic activity in both batch and flow reactors. The conversion was maintained for more than 20 h with 95% selectivity to the desired ethyl ester in the flow system.
- Taketoshi,Ishida,Murayama, Toru,Honma, Tetsuo,Haruta, Masatake
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- Borane-Catalyzed Reductive α-Silylation of Conjugated Esters and Amides Leaving Carbonyl Groups Intact
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Described herein is the development of the B(C6F5)3-catalyzed hydrosilylation of α,β-unsaturated esters and amides to afford synthetically valuable α-silyl carbonyl products. The α-silylation occurs chemoselectively, thus leaving the labile carbonyl groups intact. The reaction features a broad scope of both acyclic and cyclic substrates, and the synthetic utility of the obtained α-silyl carbonyl products is also demonstrated. Mechanistic studies revealed two operative steps: fast 1,4-hydrosilylation of conjugated carbonyls and then slow silyl group migration of a silyl ether intermediate.
- Kim, Youngchan,Chang, Sukbok
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supporting information
p. 218 - 222
(2016/01/25)
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- Asymmetric allylic alkylation of acyclic allylic ethers with organolithium reagents
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A highly efficient, regio- and enantioselective CuI/ phosphoramidite-catalyzed asymmetric allylic alkylation of allyl ethers with organolithium reagents is reported (see scheme). The use of organolithium reagents is essential for this catalytic C-C bond formation due to their compatibility with different Lewis acids. The versatility of allylic ethers under the copper-catalyzed reaction conditions with organolithium reagents is demonstrated in the shortest synthesis of (S)-Arundic acid. Copyright
- Pérez, Manuel,Fa?anás-Mastral, Martín,Hornillos, Valentín,Rudolph, Alena,Bos, Pieter H.,Harutyunyan, Syuzanna R.,Feringa, Ben L.
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supporting information
p. 11880 - 11883
(2012/10/29)
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- Rh2(OAc)4/CeCl3-catalyzed olefination of carbonylferrocenes with α-diazocarbonyl compounds: A convenient synthesis of alkenylferrocenes
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A concise and efficient protocol for the synthesis of al-kenylferrocene derivatives based on the olefination of carbonylferrocenes with α-diazocarbonyl compounds using Rh2(OAc)4/CeCl 3 as efficient catalysts was developed. The present method was applicable to many kinds of substituted carbonylferrocenes and α-diazocarbonyl compounds providing good to excellent yields of desired products. Georg Thieme Verlag Stuttgart · New York.
- Chen, Shufeng,Zhang, Lele,Du, Yan,Li, Baoguo
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experimental part
p. 943 - 947
(2012/06/04)
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- New and facile approach for the synthesis of (E)-α,β-unsaturated esters and ketones
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A general and practical synthesis of (E)-α,β-unsaturated esters and ketones was achieved by the reaction of carbonyl compounds with ethyl-4,4,4-trifluoroacetoacetate and trifluoro-substituted 1,3-diketones in the presence of piperidine in dichloromethane at raoom temperature (≈40°C) with excellent stereoselectivity (see scheme).
- China Raju, Bhimapaka,Suman, Pathi
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supporting information; experimental part
p. 11840 - 11842
(2011/01/12)
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- Intermediates for the synthesis of 4-substituted proline derivatives
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A chemoenzymatic synthesis of a series of 2-hydroxy-5-nitro-4-substituted esters is described that uses two biotransformations in a single-pot process in which a kinetic resolution/reduction occurs. The products are valuable intermediates for the preparation of 4-substituted prolines and 5-substituted 3-hydroxypiperidinones as illustrated by the preparation of (2R,4R)-4- methylproline and (3S,5R)-3-hydroxy-5-methylpiperidinone. Georg Thieme Verlag Stuttgart · New York.
- Crosby, Stuart R.,Sessions, Richard B.,Willis, Christine L.
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scheme or table
p. 539 - 542
(2010/10/02)
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- First stereoselective total synthesis and anticancer activity of new amide alkaloids of roots of pepper
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The first stereoselective total synthesis of new natural amide alkaloids 1-3 have been achieved from commercially available starting materials. Wittig olefination, Sharpless asymmetric dihydroxylation, epoxidation, a trans regioselective opening of 2,3-epoxy alcohol, Horner-Wadsworth-Emmons (HWE) olefination and amide coupling are the key steps. The amide alkaloids 1-3 are evaluated for their anticancer activity against colon (HT-29), breast (MCF-7) and lung (A-549) human cancer cell lines for the first time.
- Srinivas,Sai Pavan Kumar,China Raju,Jayathirtha Rao,Naidu,Ramakrishna,Diwan, Prakash V.
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scheme or table
p. 5915 - 5918
(2010/04/29)
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- Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
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The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica-supported PAMAM-Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.
- Zweni, Pumza P.,Alper, Howard
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p. 725 - 731
(2007/10/03)
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- Nitroalkanes and ethyl glyoxalate as common precursors for the preparation of both β-keto esters and α,β-unsaturated esters
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β-Nitro acrylic esters, obtained by the reaction of nitroalkanes and ethyl glyoxalate, are the key building blocks for the immediate synthesis of both the title compounds. In fact, their treatment with titanium trichloride produce the direct conversion to the β-keto esters, while their reaction with sodium boron hydride gives the one-pot synthesis of α,β- unsaturated esters through formal substitution of the vinylic nitro group with an hydrogen.
- Ballini, Roberto,Fiorini, Dennis,Palmieri, Alessandro
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p. 7027 - 7029
(2007/10/03)
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- N-acyl-5,5-dimethyloxazolidin-2-ones as latent aldehyde equivalents
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A study of the properties of N-hydrocinnamoyl- derivatives of 5,5-dimethyloxazolidin-2-one, 4,4-dimethyloxazolidin-2-one and oxazolidin-2-one upon hydride reduction with DIBAL-H demonstrates that the 5,5-dimethyl-group is essential for inhibition of endocyclic nucleophilic attack. For instance, treatment of N-hydrocinnamoyl-5,5-dimethyl-oxazolidin-2-one with DIBAL-H results in the selective formation of the stable N-1′-hydroxyalkyl derivative which may be regarded as a masked hydrocinnamaldehyde equivalent, as treatment under basic conditions affords the parent aldehyde in excellent yield. Treatment of N-hydrocinnamoyl-4,4-dimethyloxazolidin-2-one with DIBAL-H under identical conditions affords a complex mixture of products, including the formate ester product of endocyclic cleavage. As an alternate strategy, DIBAL-H reduction of straight chain and branched N-acyl-5,5-dimethyloxazolidin-2-one derivatives, followed by a Horner-Wadsworth-Emmons reaction affords α,β-unsaturated esters in good yields. Branching α- to the exocyclic carbonyl in N-acyl-oxazolidinones inhibits DIBAL-H reduction, but this can be overcome by precomplexation with ZnCl2, with subsequent fragmentation generating either the corresponding aldehyde or α,β-unsaturated esters. The addition of ZnCl2 has been shown to increase the diastereoselectivity observed in Wadsworth-Horner-Emmons reactions of lithiated phosphonates.
- Bach, Jordi,Blachere, Cecile,Bull, Steven D.,Davies, Stephen G.,Nicholson, Rebecca L.,Price, Paul D.,Sanganee, Hitesh J.,Smith, Andrew D.
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p. 2001 - 2010
(2007/10/03)
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- Synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae)
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We propose a new synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae) that uses a phase-transfer version of the Wittig - Horner reaction to produce a monoene synthon of the principal component of the pheromone, E-2-hexenylbutyrate.
- Shakirzyanova,Abdukakharov,Abduvakhabov
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p. 623 - 624
(2007/10/03)
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- N-acyl-5,5-dimethyl-oxazolidin-2-ones as latent aldehyde equivalents
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N-acyl-5,5-dimethyl-oxazolidin-2-ones can function as versatile latent aldehyde equivalents - reductive cleavage with DIBAL-H affords aldehydes in good yield, while tandem DIBAL-H/Wittig methodology affords α,β-unsaturated esters.
- Bach, Jordi,Bull, Steven D.,Davies, Stephen G.,Nicholson, Rebecca L.,Sanganee, Hitesh J.,Smith, Andrew D.
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p. 6677 - 6680
(2007/10/03)
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- Selective hydrogenation of simple and functionalized conjugated dienes using a binuclear palladium complex catalyst precursor
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The selective 1,2-hydrogenation of simple and functionalized conjugated dienes is catalyzed by preactivation of the binuclear palladium complex, [(Bu(t)2PH)PdPBu(t)2]2 with oxygen, in THF at room temperature and 1 atm of hydrogen pressure, to form monoenes in excellent yield.
- Cho, In Sik,Alper, Howard
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p. 5673 - 5676
(2007/10/02)
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- Colloidal palladium, easily formed in organic solvents, is a highly active and stable catalyst for selective hydrogenations and dehydrohalogenations
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Collidal Pd formed in organic solvents from Pd(hfacac)2 and silane or an Si-H- containing polymer is an active, stable and selective catalyst for hydrogenation and dehydrohalogenation.
- Fowley, Lissa A.,Michos, Demetrius,Luo, Xiao-Liang,Crabtree, Robert H.
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p. 3075 - 3078
(2007/10/02)
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- Easy preparation of a cyclobutanone ketal via a radical cyclization. The gem-dialkoxy effect
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A new method for the facile synthesis of cyclobutanones, the key step of which is a radical cyclization to generate the four-membered ring, is reported. In addition, a comparison of the gem-dialkyl and gem-dialkoxy effects in radical cyclizations to give cyclobutane systems shows that in this system the gem-dialkoxy effect is larger.
- Jung,Trifunovich,Lensen
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p. 6719 - 6722
(2007/10/02)
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- A convenient synthesis of aziridine-2-carboxylic esters
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Optically active oxirane-2-carboxylic esters, prepared from allylic alcohols employing the Sharpless epoxidation, were treated with sodium azide.The azido alcohols obtained were subsequently converted into aziridine-2-carboxylic esters by reaction with triphenylphosphine, in good yields and with high optical purity.Various racemic oxirane-2-carboxylic esters were subjected to the same sequence of reactions.
- Legters, Johan,Thijs, Lambertus,Zwanenburg, Binne
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- 1,3-Dimethyl 2-oxo 1,3,2-diazaphospholidine precursor of (Z) α,β-unsaturated esters
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α,β-Unsaturated esters of (Z) geometry are selectively obtained from cyclic phosphonocarboxylates derived from N,N'-dimethylethylenediamine.
- Patois,Savignac
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p. 1317 - 1320
(2007/10/02)
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- Studies of the use of elemento-organic compounds of the fifteenth and sixteenth groups in organic synthesis LXXI. Reaction of α-halogeno carboxylic derivatives with carbonyl compounds promoted by tributylstibine
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α,β-Unsaturated esters and amides were conveniently obtained from the trialkylstibine-promoted reaction of α-halogenocarboxylic derivatives with carbonyl compounds.In this reaction, a quaternary stibonium salt is an active intermediate that can be trapped and can undergo further reaction with the substrate.
- Huang, Yao-Zeng,Chen, Chen,Shen, Yanchang
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- NEW SYNTHETIC METHODS FOR α,β-UNSATURATED KETONES, ALDEHYDES, ESTERS AND LACTONES BY THE PALLADIUM-CATALYZED REACTIONS OF SILYL ENOL ETHERS, KETENE SILYL ACETALS, AND ENOL ACETATES WITH ALLYL CARBONATES
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Silyl enol ethers and ketene silyl acetals derived from ketones, aldehydes, esters and lactones are converted into α,β-unsaturated ketones, aldehydes and lactones by treatment with allyl carbonates in high yields using the palladium-bis(diphenylphosphino)ethane (dppe) complex as catalyst.Phosphine-free palladium catalyst instead of the palladium-phosphine complex gives a higher selectivity for the preparation of cyclopentenone, cyclooctenone, dienones, α,β-unsaturated esters and lactones.As a solvent, the use of nitriles such as acetonitrile is essential.In other solvents, allylation takes place.Enol acetates derived from ketones are converted into α,β-unsaturated ketones by reaction with allyl carbonate in acetonitrile using the palladium complex and tributyltin methoxide as bimetallic catalysts.
- Minami, Ichiro,Takahashi, Kazuhiko,Shimizu, Isao,Kimura, Tsuneo,Tsuji, Jiro
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p. 2971 - 2978
(2007/10/02)
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- Epoxidation of Fatty Acid Esters with Aqueous Hydrogen Peroxide in the Presence of Molybdenum Oxide-Tributyltin Chloride on Charcoal Catalyst
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The epoxidation of fatty acid esters was carried out with a 30percent aqueous hydrogen peroxide in the presence of a molybdenum oxide-tributyltin chloride on a charcoal catalyst in 2-propanol at 50 degC.Such inner olefins as ethyl erucate and ethyl oleate gave good yields of 77 and 76percent, respectively.Ethyl elaidate, a trans-form of ethyl oleate, was less reactive (40percent yield).Several vegetable oils such as rapeseed oil, olive oil, soybean oil, cottonseed oil, corn oil, and linseed oil were oxidized with the oxirane oxygen contents of 5.3 to 3.5percent.
- Itoi, Yasushi,Inoue, Masami,Enomoto, Saburo
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p. 3941 - 3944
(2007/10/02)
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- A NOVEL OLEFINATION OF CARBONYL COMPOUNDS WITH α-BROMOACETIC ESTER MEDIATED BY TRI-n-BUTYLSTIBINE
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Tri-n-butylstibine has been found to mediate the olefination of carbonyl compounds by α-bromoacetic ester to give corresponding olefins in good yields.
- Huang, Yaozeng,Shen, Yanchang,Chen, Chen
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p. 2903 - 2904
(2007/10/02)
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- Mechanism of Formation of α,β-Unsaturated Esters in the Reaction of Ethyl Mercaptoacetate Dianion with Carbonyl Compounds
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Dianion derived fron ethyl mercaptoacetate undergoes aldol type reaction with a carbonyl compounds to give an adduct, which exhibited low diastereoselectivity.However, the adducts obtained by the reaction with a variety of aldehydes were subsequently treated with ethyl chloroformate in the presence of trivalent phosphorus compound to give (E)-isomers of α,β-unsaturated esters in high yields with greater than 85percent stereoselectivity regardless of the stereochemistry of the diastereomers of the adducts.The stereochemical mechanism and application of this reaction were studied in detail.
- Matsui, Syuichi
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p. 426 - 434
(2007/10/02)
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- PALLADIUM-CATALYZED PREPARATION OF α-ALLYL ESTERS AND α,β-UNSATURATED ESTERS FROM SATURATED ESTERS VIA THEIR KETENE SILYL ACETALS
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Reaction of ketene silyl acetals with allylic carbonates in the presence of palladium-phosphine catalyst in dioxane gives α-allyl esters in high yields.When the reaction is carried out with phosphine-free palladium catalyst in nitriles, α,β-unsaturated esters are obtained in good yields.
- Tsuji, Jiro,Takahashi, Kazuhiro,Minami, Ichiro,Shimizu, Isao
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p. 4783 - 4786
(2007/10/02)
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- THE EFFECT OF THE PHOSPHORYL SUBSTITUENTS ON THE STEREOCHEMISTRY OF THE HORNER REACTION
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The stereochemistry of the olefin forming reaction of various phosphoryl stabilized carbanions and aldehydes in ethanol is reported.The aromatic aldehydes react with acyclic phosphoryl stabilized carbanions yielding the trans isomers stereoselectively, whereas the 5- and 6-membered cyclic phosphonates (II and III) resulted in high yields of cis isomeric olefins.The aliphatic aldehydes give rise to considerable amounts of cis olefins also, decreasing in the series phosphonates, phosphinates and phosphine oxides, respectively.The stereochemical results are discussed in terms of pentacoordinated reaction intermediates.
- Larsen, Rolf Olaf,Aksnes,Gunnar
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p. 339 - 344
(2007/10/02)
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- The Synthesis and Ring-contraction of Halogenated Hydroxyquinones; a New Synthesis of Cryptosporiopsin
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Syntheses of 2,6-dichloro- and 2,6-dibromo-3-hydroxy-5-alkyl-1,4-benzoquinones have been developed involving oxidation of trihalogenoresorcinol derivatives with Fremy's salt.The reactions of these quinones have been studied and their ring-contraction to cyclopentenoid structures on treatment with N-halogenosuccinimides is reported.This sequence of reactions has been used in an efficient synthesis of the fungal metabolite cryptosporiopsin.
- Henderson, Graeme B.,Hill, Robert A.
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p. 2595 - 2599
(2007/10/02)
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- Synergistic composition comprising PGF2α and PGE2
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A synergistic composition comprising as active ingredients a PGF2α compound or its cyclodextrin clathrate thereof and a PGE2 compound or its cyclodextrin clathrate thereof, at a weight ratio of from about 1:0.33 to about 1:1.
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