- Diastereoselective Synthesis of Highly Substituted Tetrahydropyran-4-ones
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(Matrix Presented) Aldol reactions of β-ketoesters with aldehydes followed by a tandem Knoevenagel condensation, with a further equivalent of aldehyde, and intramolecular Michael addition produces single diastereomers of highly substituted tetrahydropyran-4-ones.
- Clarke, Paul A.,Martin, William H. C.
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- Calix[n]arene/Ti(IV) complexes as active catalysts in aldol reaction of Chan's diene
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The aldol condensation of Chan's diene with benzaldehyde is catalyzed by only 8% mol of the calix[n]arene/Ti(O-i-Pr)4 complexes. Studies have revealed that the size of calixarene molecule and the number of hydroxyl groups affected the efficienc
- Soriente, Annunziata,Fruilo, Marina,Gregoli, Luisa,Neri, Placido
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Read Online
- Investigation of the mechanism for the preparation of 6-phenyl-2,4- dioxotetrahydropyrans by the potassium carbonate promoted condensation between acetoacetate esters and benzaldehyde
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Treatment of benzaldehyde and an acetoacetate ester with potassium carbonate in an alcohol solvent proceeds via γ-C-alkylation rather than α-C-alkylation resulting in the formation of 6-phenyl-2,4- dioxotetrahydropyran. Based upon results from deuterium e
- Andersh, Brad,Nguyen, Elizabeth T.,Van Hoveln, Ryan J.,Kemmerer, Dylan K.,Baudo, David A.,Graves, Jessica A.,Roark, Mollie E.,Bosma, Wayne B.
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p. 4563 - 4567
(2013/06/05)
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- A short and convenient strategy for the synthesis of pyridazines via Diaza-Wittig reaction
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A convenient and selective synthesis of 6-substituted-4-hydroxy-3- methoxycarbonyl pyridazines has been developed via a diaza-Wittig reaction. The desired products substituted at the C6 position can be obtained from readily available starting materials under mild conditions. This represents an attractive new method for the synthesis of pyridazine derivatives.
- Bel Abed, Hassen,Herdewijn, Piet,Mammoliti, Oscar,Van Lommen, Guy
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supporting information
p. 6489 - 6491,3
(2012/12/12)
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- A short and convenient strategy for the synthesis of pyridazines via Diaza-Wittig reaction
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A convenient and selective synthesis of 6-substituted-4-hydroxy-3- methoxycarbonyl pyridazines has been developed via a diaza-Wittig reaction. The desired products substituted at the C6 position can be obtained from readily available starting materials under mild conditions. This represents an attractive new method for the synthesis of pyridazine derivatives.
- Bel Abed, Hassen,Mammoliti, Oscar,Van Lommen, Guy,Herdewijn, Piet
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supporting information
p. 6489 - 6491
(2013/01/15)
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- Synthesis of multifunctionalized building blocks via vinylogous addition of Chan's diene to carbonyl and carbonyl-related electrophiles, mediated by molecular iodine
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The synthesis of multifunctionalized β-ketoesters has been achieved by using molecular iodine as a catalyst under very mild conditions. The vinylogous addition of Chan's diene 1 to carbonyl and carbonyl-related compounds (aldehydes, ketones, imines and acetals) occurred with high efficiencies and with complete γ-selectivity, giving a useful method for the synthesis of interesting libraries of different δ-functionalized β-ketoesters.
- Villano, Rosaria,Acocella, Maria R.,Scettri, Arrigo
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experimental part
p. 2768 - 2772
(2011/04/27)
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- Biomimetic synthesis of hyperolactones
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Through a biomimetic pathway, hyperolactone D, 4-hydroxyhyperolactone D, and hyperolactone C were synthesized from methyl acetoacetate via Weilers dianion method, asymmetric allylic alkylation, biomimetic lactonization, oxidation, and cyclization. The stereochemistry of the quaternary carbon was controlled efficiently by Palladium-catalyzed asymmetric allylic alkylation. This strategy was also used for the synthesis of hyperolactone B.
- Wu, Yingying,Du, Chao,Hu, Congcong,Li, Ying,Xie, Zhixiang
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supporting information; experimental part
p. 4075 - 4081
(2011/06/26)
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- Structure-activity relationship study of first selective inhibitor of excitatory amino acid transporter subtype 1: 2-Amino-4-(4-methoxyphenyl)-7- (naphthalen-1-yl)-5-oxo-5,6,7,8-tetrahydro-4 H -chromene-3-carbonitrile (UCPH-101)
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The excitatory amino acid transporters (EAATs) are expressed throughout the central nervous system, where they are responsible for the reuptake of the excitatory neurotransmitter (S)-glutamate (Glu).(1)Recently, we have reported the discovery of the first subtype selective EAAT1 inhibitor 2-amino-4-(4-methoxyphenyl)-7-(naphthalen-1-yl)-5-oxo-5,6,7,8-tetrahydro-4H- chromene-3-carbonitrile (UCPH-101) (1b) and presented an introductory structure-activity relationship (SAR) study.(2)Here, we present a detailed SAR by the design, synthesis, and pharmacological evaluation of analogues 1g-1t. By comparison of potencies of 1b, 1h, and 1i versus 1j, it is evident that potency is largely influenced by the chemical nature of the R1 substituent. The study also demonstrates that any chemical change of the functional groups or a change to the parental scaffold results in the complete loss of inhibitory activity of the compounds at EAAT1. Finally, a bioavailability study of UCPH-101 determined the half-life to be 30 min in serum (rats) but also that it was not able to penetrate the blood-brain barrier to any significant degree.
- Erichsen, Mette N.,Huynh, Tri H. V.,Abrahamsen, Bjarke,Bastlund, Jesper F.,Bundgaard, Christoffer,Monrad, Olja,Bekker-Jensen, Anders,Nielsen, Christina W.,Frydenvang, Karla,Jensen, Anders A.,Bunch, Lennart
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experimental part
p. 7180 - 7191
(2010/12/25)
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- Solvent-free asymmetric vinylogous aldol reaction of Chan's diene with aromatic aldehydes catalyzed by hydrogen bonding
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Chan's diene proved to react with aromatic aldehydes under organocatalytic conditions in presence of a chiral naphthyl-TADDOL derivative to give vinylogous aldols (up to 65% ee) with complete γ-selectivity. A further process of hetero-Diels-Alder cycloadd
- Villano, Rosaria,Acocella, Maria Rosaria,Massa, Antonio,Palombi, Laura,Scettri, Arrigo
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scheme or table
p. 5571 - 5576
(2009/12/01)
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- Construction of two vicinal quaternary carbons by asymmetric allylic alkylation: Total synthesis of hyperolactone C and (-)-biyouyanagin A
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Call on triple A: Palladium-catalyzed asymmetric allylic alkylation (Pd-AAA; see scheme) has enabled a concise and efficient synthesis of hyperolacto ne C and (-)-biyouyanagin A in only six (20% Overall yield) and seven (8% overall yield) steps, respectively. The enantiomers of these natural products were also prepared by exploiting the same methodology.
- Du, Chao,Li, Liqi,Li, Ying,Xie, Zhixiang
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supporting information; experimental part
p. 7853 - 7856
(2010/04/05)
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- A new procedure for the enantioselective vinylogous aldol reaction of Chan's diene
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Chiral δ-hydroxy-β-ketoesters are easily available through the enantioselective vinylogous aldol reaction of Chan's diene promoted by a SiCl4/chiral phosphoramide catalytic system. The procedure is conveniently exploited for a very rapid approach to (+)-kavain, a natural bio-active α-pyrone compound.
- Villano, Rosaria,Acocella, Maria Rosaria,Massa, Antonio,Palombi, Laura,Scettri, Arrigo
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p. 3332 - 3334
(2007/10/03)
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- The one-pot, multi-component construction of highly substituted tetrahydropyran-4-ones using the Maitland-Japp reaction
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A one-pot, multi-component reaction for the synthesis of highly substituted tetrahydropyran-4-ones, based on the long forgotten Maitland-Japp reaction has been realised. Two different aldehydes and a derivative of a β-ketoester can be condensed regioselectively in the presence of a Lewis acid to form tetrahydropyran-4-ones in excellent yields. The diastereoselectively of the reaction was found to be dependant upon the nature of the Lewis acid and the temperature at which the reaction was carried out. This procedure was also extended to the formation of tetrahydropyran-4-ones in greater than 95% enantiomeric excess. The Royal Society of Chemistry 2005.
- Clarke, Paul A.,Martin, William H. C.,Hargreaves, Jason M.,Wilson, Claire,Biake, Alexander J.
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p. 3551 - 3563
(2007/10/03)
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- Candida Rugosa lipase-catalyzed kinetic resolution of β-hydroxy- β-arylpropionates and δ-hydroxy-δ-aryl-β-oxo-pentanoates
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A simple and convenient method was reported for the preparation of optically active β-hydroxy-β-arylpropionates, δ-hydroxy-δ- aryl-β-oxo-pentanoates and their butyryl derivatives via CRL-catalyzed hydrolysis. The optically active products are potential precursors of some chiral pharmaceuticals and natural products.
- Xu, Chengfu,Yuan, Chengye
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p. 2169 - 2186
(2007/10/03)
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- Silicon tetrachloride in organic synthesis: New applications for the vinylogous aldol reaction
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This paper describes a novel and efficient methodology for vinylogous aldol reactions based on SiCl4 catalysis. According to the nucleophilicity Mayr's scale, vinylogous aldol reaction of Chan's diene proved to be effective by using catalytic amount of SiCl4, without any other promoter. On the contrary, the SiCl4/Lewis base system has been conveniently exploited for the efficient and selective vinylogous reaction of less nucleophilic Danishefsky's diene and 2-trimethylsilyloxyfuran (TMSOF). Indeed, a number of Lewis bases, such as sulfoxides, formamides and phosphoramides have been successfully used as SiCl4 promoters. TMSOF and silyloxydienes, resulting from 2,2,6-trimethyl-[1,3]-dioxin-4-one derivatives, required stoichiometric amount of SiCl4, while vinylogous aldol reaction of Chan's and Danishefsky's dienes took satisfactorily place in the presence of catalytic or sub-stoichiometric amount of catalyst.
- Acocella, Maria R.,De Rosa, Margherita,Massa, Antonio,Palombi, Laura,Villano, Rosaria,Scettri, Arrigo
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p. 4091 - 4097
(2007/10/03)
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- A Chemoenzymatic Approach to Optically Active 5-Hydroxy-3-oxocarboxylates
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Enzymatic hydrolysis was applied to the preparation of certain chiral 5-hydroxy-3-oxo-carboxylates that are potential precursors for natural product synthesis via the formation of lactone derivatives and tetrahydropyran rings.
- Xu, Chengfu,Zhang, Yonghui,Yuan, Chengye
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p. 485 - 488
(2007/10/03)
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- Asymmetric aldol reaction of enol trichloroacetate catalyzed by tin methoxide and BINAP·silver(I) complex
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Enol trichloroacetate of cyclohexanone has been found to react with benzaldehyde in the presence of a catalytic amount of tributyltin methoxide and stoichiometric amount of MeOH to give an aldol adduct. Methanolysis of the in situ generating tin alkoxide of aldol adduct regenerates the tin methoxide, and thus the aldol reaction can proceed catalytically. The use of BINAP·silver(I) complex as an additional catalyst results in formation of optically active aldol products. This catalytic method has been further applied to the asymmetric reaction of diketene with benzaldehyde.
- Yanagisawa, Akira,Matsumoto, Yukari,Asakawa, Kenichi,Yamamoto, Hisashi
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p. 8331 - 8339
(2007/10/03)
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- Synthesis of 3- and 5-alkyl-6-alkyl(aryl)tetrahydropyran-2,4-diones by the condensation of β-oxo acid esters with aldehydes and ketones
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A method is proposed for obtaining 3- and 5-alkyl-6-alkyl(aryl)tetrahydropyran-2,4-diones based on the condensation of the dianion of alkyl(dialkyl)acetoacetic ester with aldehydes and ketones.
- Lokot',Pashkovskii,Lakhvich
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p. 707 - 714
(2007/10/03)
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- STUDIES ON THE DIASTEREOSELECTIVE REDUCTION OF β-HYDROXY KETONES TO 1,3-DIOLS WITH COMMON HYDRIDE REAGENTS
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Some common reducing agents were employed in the diastereoselective reduction of several β-hydroxy ketones to their corresponding syn-1,3-diols.The use of NaBH4 with a Ti(IV) chelating species produced syn diols with a moderate to good selectivity significantly depending upon the reaction conditions chosen (solvent, temperature, nature of the titanium species).The use of LiAlH4 at low temperature, in the presence of LiI, showed a high selectivity for reduction to syn diols, thus demonstrating a possible chelating role of lithium.Some interesting preliminary results have been also obtained in the diastereoselective reduction of MEM-protected β-alkoxy ketones.
- Bonini, Carlo,Bianco, Armandodoriano,Fabio,Romano Di,Mecozzi, Sandro,Proposito, Alessandro,Righi, Giuliana
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- SYNTHESIS OF A PROSTAGLANDIN ENDOPEROXIDE MODEL COMPOUND AND ITS REACTION WITH ELECTRON TRANSFER REAGENTS
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5-Exo-phenyl-2,3-dioxabicycloheptane (4c) was synthesized as a model compound of prostaglandin endoperoxide (PGH) to mimic the bioconversion of PGH into thromboxane (TX).The reaction of (4c) with various electron transfer reagents was investigated.With the aid of a catalytic amount of ferrous ion, (4c) was successfully converted into the thromboxane B (TXB) skeleton.
- Takahashi, Kimio,Kishi, Morio
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p. 4737 - 4746
(2007/10/02)
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- EFFICACIOUS ENTRY INTO SUBSTITUTED 5,6-DIHYDRO-4-HYDROXY-2H-PYRAN-2-ONES AND 2,3-DIHYDRO-4H-PYRAN-4-ONES UTILIZING KETONIC DIANIONS
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Methyl acetoacetate and 2,4-pentanedione dianions were condensed with aldehydes and ketones to afford a 1,3,5-trioxygenated carboskeleton.Intramolecular cyclization of the aldol adducts delivered the title compounds in good yield.
- Peterson, John R.,Winter, Tamara J.,Miller, Chris P.
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p. 949 - 964
(2007/10/02)
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- An Electron Transfer Model for Thromboxane Biosynthesis
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Conversion of prostaglandin endoperoxide model compound (1) into the thromboxane B ring system (6a) and (7a) was achieved with the aid of the ferrous ion.
- Takahashi, Kimio,Kishi, Morio
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p. 722 - 724
(2007/10/02)
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- Chemistry of enol silyl ethers. A general synthesis of 3-hydroxyhomophthalates and a biomimetic synthesis of sclerin
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A general synthesis of 3- hydroxyhomophthalates is developed and applied to the synthesis of sclerin (24), a compound possessing plant-growth activity; the critical step in the synthesis of 24 can be considered as the controlled condensation of a di-β-carbonyl unit with a tri-β-carbonyl unit.
- Brownbridge, P.,Chan, T. H.,Brook, M. A.,Kang, G. J.
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p. 688 - 693
(2007/10/02)
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