- Synthesis of Ketones by C?H Functionalization of Aldehydes with Boronic Acids under Transition-Metal-Free Conditions
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A method for the synthesis of ketones from aldehydes and boronic acids via a transition-metal-free C?H functionalization reaction is reported. The method employs nitrosobenzene as a reagent to drive the simultaneous activation of the boronic acid as a boronate and the activation of the C?H bond of the aldehyde as an iminium species that triggers the key C?C bond-forming step via an intramolecular migration from boron to carbon. These findings constitute a practical, scalable, and operationally straightforward method for the synthesis of ketones.
- Roscales, Silvia,Csáky, Aurelio G.
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supporting information
p. 8728 - 8732
(2021/03/16)
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- Asymmetric Construction of α-Substituted β-Hydroxy Lactones via Ni Catalyzed Decarboxylative Addition Reaction
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We described a Ni-bidentate oxazoline catalyzed highly enantio- and diastereoselective decarboxylative aldol reaction of 2-oxotetrahydrofuran-3-carboxylic acid/2-oxochromane-3-carboxylic acid derivatives with different kinds of carbonyls. Under optimal reaction conditions, α-substituted β-hydroxy butyrolactones and dihydrocoumarins with an all-carbon quaternary stereocenter have been generated with high levels of functional-group compatibility. Furthermore, proficient transformations of products were also described, in which an aliphatic tertiary alcohol and a multi-substituted 1,4-diol were smoothly constructed through hydrogenation and ring-opening reaction, respectively.
- He, Lingchen,Ahmed, Ebrahim-Alkhalil M. A.,Liu, Hongxin,Hu, Xingen,Xiao, Hong-Ping,Li, Juan,Jiang, Jun
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p. 4825 - 4834
(2021/04/02)
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- Iodine mediated a simple strategy for the synthesis of β,γ-unsaturated-α-ketoesters and its application for the synthesis of 4,5-dihydropyrazole derivatives
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Abstract: Novel and efficient method for the synthesis of a series of β,γ-unsaturated-α-ketoesters under mild conditions was developed. This one-step protocol was achieved by the reaction of electron-rich aromatic aldehydes and pyruvates in the presence o
- Pommidi, Anil,Shaik, Asha Begum,Chatterjee, Anindita,Somarapu, Vijaya Laxmi
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p. 1545 - 1553
(2020/03/05)
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- Diversity-Oriented Synthesis of Spirocyclohexene Indane-1,3-diones and Coumarin-Fused Cyclopentanes via an Organobase-Controlled Cascade Reaction
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An organobase-controlled, divergent cascade reaction to construct spirocyclohexene indane-1,3-diones and coumarin-fused cyclopentanes is reported. The cascade reaction is triggered by the 1,6-addition of 3-homoacylcoumarins to the indanedione-derived acce
- Wang, Min,Tseng, Ping-Yao,Chi, Woei-Jye,Suresh, Sundaram,Edukondalu, Athukuri,Chen, Yi-Ru,Lin, Wenwei
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p. 3407 - 3415
(2020/07/16)
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- Direct Synthesis of β,γ-Unsaturated α-Keto Esters from Aldehydes and Pyruvates
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Herein, we describe two practical methods to synthesize β,γ-unsaturated α-keto esters directly from aldehydes and pyruvates promoted by BF 3 ?Et 2 O in the presence of Ac 2 O or by Ti(OEt) 4 under mild condition
- Mansaray, John Kamanda,Sun, Jiarui,Huang, Shisheng,Yao, Weijun
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supporting information
p. 809 - 813
(2019/04/25)
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- Facile synthesis of substituted diaryl sulfones: Via a [3 + 3] benzannulation strategy
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A base-mediated [3 + 3] benzannulation strategy for the conversion of 1,3-bis(sulfonyl)propenes and β,γ-unsaturated α-ketoesters to diaryl sulfones has been developed. This method provides facile, metal-free and efficient access to highly substituted diaryl sulfones in good to excellent yields. In addition, the sulfonyl group could be easily removed or converted to other functional groups via an organostannane intermediate.
- Tang, Xiang-Zheng,Tong, Lang,Liang, Hua-Ju,Liang, Jie,Zou, Yong,Zhang, Xue-Jing,Yan, Ming,Chan, Albert S. C.
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supporting information
p. 3560 - 3563
(2018/05/26)
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- Catalytic Generation of Donor-Acceptor Cyclopropanes under N-Heterocyclic Carbene Activation and their Stereoselective Reaction with Alkylideneoxindoles
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Formylcyclopropanes undergo activation in the presence of an N-heterocyclic carbene catalyst generating a donor-acceptor cyclopropane intermediate with the ability to undergo ring-opening followed by formal [4+2] cycloaddition with alkylideneoxindoles. This enables the direct enantio- and diastereoselective synthesis of tetrahydropyrano[2,3-b]indoles through the use of a chiral NHC catalyst. (Figure presented.).
- Prieto, Liher,Sánchez-Díez, Eduardo,Uria, Uxue,Reyes, Efraím,Carrillo, Luisa,Vicario, Jose L.
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p. 1678 - 1683
(2017/05/22)
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- α-Alkoxycarbonyl-α-hydroxy secondary amides from a carbamoylsilane and α-ketoesters
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The addition of N-methoxymethyl-N-organylcarbamoyl(trimethyl)silane to α-ketoesters in anhydrous toluene at 60 °C afforded α-alkoxycarbonyl-α-siloxy amides in high yields (75–96%). The methoxymethyl was used as an amino protecting group and could be easily converted into hydrogen atom by simple acid hydrolysis leading to α-alkoxycarbonyl-α- hydroxy secondary amides.
- Li, Weidong,Han, Yuling,Chen, Jianxin
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p. 5813 - 5819
(2017/09/05)
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- A process for preparing (R) - 2-hydroxy-4-phenyl-butyric acid ethyl ester method (by machine translation)
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The invention provides a process for preparing (R)? 2? Hydroxy? 4? Phenyl ethyl butyrate method of, in a cheap and easily obtained benzald and pyruvic acid as a raw material, by condensation, esterification, biological enzyme-catalyzed asymmetric reduction and double bond hydrogenated four-step efficient reaction, in order to eventually 82% overall yield of optically pure target product obtained (R)? HPBE. (by machine translation)
- -
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Paragraph 0040; 0044; 0045; 0048
(2016/10/10)
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- Synthesis of 1,2-Dicarbonyl-3-enes by Hydroacylation of 1-Alkynes with Glyoxal Derivatives Using Metal-Organic Framework Cu/MOF-74 as Heterogeneous Catalyst
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A crystalline copper-based metal-organic framework Cu/MOF-74 was synthesized, and used as an efficient heterogeneous catalyst for the synthesis of 1,2-dicarbonyl-3-enes by means of the hydroacylation of 1-alkynes with glyoxal derivatives in the presence o
- Nguyen, Nguyen B.,Dang, Giao H.,Le, Dung T.,Truong, Thanh,Phan, Nam T. S.
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p. 361 - 369
(2016/04/26)
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- A New Strategy for Enantioselective Construction of Multisubstituted Five-Membered Oxygen Heterocycles via a Domino Michael/Hemiketalization Reaction
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A new highly enantioselective domino Michael/hemiketalization reaction of α-hydroxyacetophenone with β,γ-unsaturated α-keto esters for the synthesis of 2,2,4,5-tetrasubstituted chiral tetrahydrofurans is reported. With 2 mol% intramolecular dinuclear zinc
- Hua, Yuan-Zhao,Liu, Meng-Meng,Huang, Pei-Jin,Song, Xixi,Wang, Min-Can,Chang, Jun-Biao
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supporting information
p. 11994 - 11998
(2015/08/18)
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- Synthesis in ionic liquids only: Access to α-oxo-γ-thio-esters via Mukaiyama coupling
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Ionic liquids are solvents general enough to conduct a multi-step process in organic synthesis. We show that both the preparation of starting materials (thioacetals and enoxysilane) as well as their coupling can be realized in such medium.
- Jebri, Khouloud,Mazières, Marie-Rose,Ballereau, Stéphanie,Ben Ayed, Ta?cir,Plaquevent, Jean-Christophe,Baltas, Michel,Guillen, Frédéric
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p. 1353 - 1356
(2014/03/21)
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- CuBr-promoted formal hydroacylation of 1-alkynes with glyoxal derivatives: An unexpected synthesis of 1,2-dicarbonyl-3-enes
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An efficient and concise protocol has been developed for the highly regio- and stereoselective synthesis of E-1,2-dicarbonyl-3-ene derivatives by a copper-promoted reaction of 1-alkynes with α-carbonyl aldehydes in the presence of morpholine. The products obtained are believed as the formal hydroacylation of the triple bond.
- Chen, Shufeng,Li, Xiaojie,Zhao, Haiying,Li, Baoguo
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p. 4137 - 4141
(2014/05/20)
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- Gold(I)-catalyzed diastereoselective hydroacylation of terminal alkynes with glyoxals
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The reaction of an α-ketoaldehyde and a terminal alkyne in the presence of piperidine and a catalytic amount of AuCl delivers 1,2-dicarbonyl-3-enes, products of the formal hydroacylation of the triple bond. The scope of the method is broad; different aryl substituents on the dicarbonyl unit and on the alkyne are well tolerated. The products can be transformed selectively into vinylquinoxalines. Mechanistic studies, including isotope-labeling experiments, indicate that after an initial A3-type conversion to propargylic amines, a subsequent base-mediated alkyne-to-allene isomerization and a hydrolysis of the enamine substructure during the workup deliver the formal hydroacylation products. The simple AuCl catalyst and piperidine convert terminal alkynes and α-ketoaldehydes into 1,2-dicarbonyl-3-enes, the products of a formal hydroacylation of the triple bond, with excellent regio- and diastereoselectivity. There is no evidence for classical A3 coupling products, which could be expected from such a gold-catalyzed reaction of an aldehyde, an amine, and a terminal alkyne. Copyright
- Shi, Shuai,Wang, Tao,Weingand, Vanessa,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 1148 - 1151
(2014/03/21)
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- SUBSTITUTED DIHYDROPYRAZOLES AS SPHINGOSINE RECEPTOR MODULATORS
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The present invention relates to substituted dihydropyrazoles, processes for preparing them, pharmaceutical compositions containing them and their use as pharmaceuticals as modulators of sphingosine-1-phosphate receptors.
- -
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- SUBSTITUTED PYRAZOLES AS SPHINGOSINE RECEPTOR MODULATORS
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The present invention relates to substituted pyrazoles, processes for preparing them, pharmaceutical compositions containing them and their use as pharmaceuticals as modulators of sphingosine-1-phosphate receptors.
- -
-
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- SUBSTITUTED PYRAZOLE AZETIDINES AS SPHINGOSINE RECEPTOR MODULATORS
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The present invention relates to substituted pyrazole azetidines, processes for preparing them, pharmaceutical compositions containing them and their use as pharmaceuticals as modulators of sphingosine-1-phosphate receptors.
- -
-
Paragraph 0129-0131
(2014/08/19)
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- Regioselective tandem N-alkylation/ C-acylation of β,γ-alkynyl α-imino esters
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A new synthesis of α-quaternary alkynyl amino esters and allenoates was developed utilizing umpolung N-addition to β,γ-alkynyl α-imino esters followed by regioselective acylation. The reaction exhibits broad substrate generality and unique regioselectivity. Moreover, synthesis of α-quaternary alkynyl amino esters was also carried out via oxidation of the intermediary enolate followed by alkylation.
- Mizota, Isao,Matsuda, Yuri,Kamimura, Satoshi,Tanaka, Hirotaka,Shimizu, Makoto
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supporting information
p. 4206 - 4209
(2013/09/12)
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- Efficient enantioselective synthesis of dihydropyrans using a chiral N, N ′-dioxide as organocatalyst
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The bifunctional organocatalyst C3 N,N′-dioxide has been successfully applied to the asymmetric cascade Michael/hemiacetalization reaction of α-substituted cyano ketones and β,γ-unsaturated α-ketoesters for the synthesis of multifunctionalized chiral dihydropyrans. The corresponding products were obtained in excellent yields (up to 99%) with high to excellent enantioselectivities (up to 99% ee).
- Feng, Juhua,Fu, Xuan,Chen, Zhenling,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 2640 - 2643
(2013/07/19)
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- Oxone-mediated oxidative cleavage of β-keto esters and 1,3-diketones to α-keto esters and 1,2-diketones in aqueous medium
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A versatile and highly efficient method for the direct synthesis of α-keto esters and 1,2-diketones has been developed. This approach utilizes the oxidative cleavage of a variety of β-keto esters and 1,3-diketones mediated by an Oxone/aluminum trichloride system. The simple one-step oxidation reaction proceeded selectively in aqueous media to afford products in high yields, short reaction times, and environmentally benign conditions.
- Stergiou, Anastasios,Bariotaki, Anna,Kalaitzakis, Dimitris,Smonou, Ioulia
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p. 7268 - 7273
(2013/08/15)
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- A mild method for indium(III)-catalyzed 1,4-hydrosilylation of α,β-enone esters with triethylsilane and trifluoroacetic acid
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A chemo- and stereoselective 1,4-hydrosilylation of α,β-enone esters was developed using triethylsilane and trifluoroacetic acid under indium chloride catalysis. Georg Thieme Verlag Stuttgart ? New York.
- Xing, Ping,Zang, Wei,Huang, Zuo-Gang,Zhan, Yue-Xiong,Zhu, Chuan-Jun,Jiang, Biao
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supporting information
p. 2269 - 2273
(2012/10/30)
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- Enantioselective copper-catalyzed conjugate addition of trimethylaluminium to β,γ-unsaturated α-ketoesters
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Not a cop out: The copper-catalyzed asymmetric conjugate addition of organometallic reagents to Michael acceptors is an important methodology for forming a C-C bond in an enantioselective manner. Such an addition of Me 3Al to β,γ-unsaturated α-
- Gremaud, Ludovic,Alexakis, Alexandre
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p. 794 - 797
(2012/03/09)
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- Organocatalytic Functionalization of carboxylic acids: Isothiourea- catalyzed asymmetric intra- and intermolecular Michael addition-lactonizations
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Tetramisole promotes the catalytic asymmetric intramolecular Michael addition-lactonization of a variety of enone acids, giving carbo- and heterocyclic products with high diastereo- and enantiocontrol (up to 99:1 dr, up to 99% ee) that are readily derivatized to afford functionalized indene and dihydrobenzofuran carboxylates. Chiral isothioureas also promote the catalytic asymmetric intermolecular Michael addition-lactonization of arylacetic acids and α-keto-β,γ-unsaturated esters, giving anti-dihydropyranones with high diastereo- and enantiocontrol (up to 98:2 dr, up to 99% ee).
- Belmessieri, Dorine,Morrill, Louis C.,Simal, Carmen,Slawin, Alexandra M. Z.,Smith, Andrew D.
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supporting information; experimental part
p. 2714 - 2720
(2011/04/23)
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- Highly enantioselective intermolecular stetter reactions of β-aryl acceptors: α-ketoester moiety as handle for activation and synthetic manipulations
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The use of β,γ-unsaturated-α-ketoesters in the intermolecular Stetter reaction furnishes 1,2,5-tricarbonyl compounds in high yield and excellent enantioselectivity. The α,δ-diketoesters generated using this methodology serve as useful synthetic building b
- Sanchez-Larios, Eduardo,Thai, Karen,Bilodeau, Francois,Gravel, Michel
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p. 4942 - 4945
(2011/11/29)
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- Design and synthesis of 2,4-disubstituted polyhydroquinolines as prospective antihyperglycemic and lipid modulating agents
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A series of 2,4-disubstituted polyhydroquinoline were synthesized and evaluated for their in vivo antihyperglycemic as well as antidyslipidemic activities. Several synthesized compounds have exhibited promising in vivo antihyperglycemic in SLM, STZ-S, and db/db mice model along with significant lipid and TG modulating activity. All these compounds were evaluated in various in vitro models of diabetes to know the possible mechanism of their antihyperglycemic action. Interestingly, compounds 3a-r (diaryl substitution) have exhibited promising protein-tyrosine phosphatase 1B (PTP1B) inhibitory activity whereas, compounds 5a-d (acid substituted) have shown significant glycogen phosphorylase activity.
- Kumar, Atul,Sharma, Siddharth,Tripathi, Vishwa Deepak,Maurya, Ram Awatar,Srivastava, Swayam Prakash,Bhatia, Gitika,Tamrakar,Srivastava, Arvind Kumar
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experimental part
p. 4138 - 4148
(2010/08/06)
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- Highly enantioselective sequential hydrogenation of ethyl 2-Oxo-4-arylbut-3-enoate to ethyl 2-hydroxy-4-arylbutyrate
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(Chemical Equation Presented) The hydrogenation of (E)-ethyl 2-oxo-4-arylbut-3-enoate with [NH2Me2]+[{RuCl [(S)-SunPhos]}2(μ-Cl3)] gave ethyl 2-hydroxy-4- arylbutyrate with 94-96% ee. Further investigation has proved that the hydrogenation proceeded via a sequential hydrogenation of C=O and C=C bonds, which is sensitive to the reaction temperature. Hydrolysis of ethyl 2-hydroxy-4-phenylbutyrate (ee 93%) provided the 2-hydroxy-4-phenylbutyric acid with 81% yield at 99% ee after a single recrystallization from 1, 2-dichloroethylene.
- Meng, Qinghua,Zhu, Lufeng,Zhang, Zhaoguo
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supporting information; experimental part
p. 7209 - 7212
(2009/05/07)
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- Multi-component coupling synthesis of polycyclic pyrrole derivatives via Ir- and Rh-catalyzed cycloisomerizations with microwave heating
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CuBr2-catalyzed three-component coupling of N-benzylallylamine, ethyl glyoxalate, and terminal alkynes afforded glycinate-tethered 1,6-enynes, which were further transformed into polycyclic pyrrole-2-carboxylates via iridium-catalyzed cycloisom
- Yamamoto, Yoshihiko,Hayashi, Hiroki
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p. 10149 - 10160
(2008/02/13)
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- Diaryl dihydropyrazole-3-carboxamides with significant in vivo antiobesity activity related to CB1 receptor antagonism: Synthesis, biological evaluation, and molecular modeling in the homology model
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A number of analogues of diaryl dihydropyrazole-3-carboxamides have been synthesized. Their activities were evaluated for appetite suppression and body weight reduction in animal models. Depending on the chemical modification of the selected dihydropyrazole scaffold, the lead compounds - the bisulfate salt of (±)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4,5-dihydro-1H-pyrazole-3- carboxylic acid morpholin-4-ylamide 26 and the bisulfate salt of (-)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4,5-dihydro-1H-pyrazole-3- carboxylic acid morpholin-4-ylamide 30-showed significant body weight reduction in vivo, which is attributed to their CB1 antagonistic activity and exhibited a favorable pharmacokinetic profile. The molecular modeling studies also showed interactions of two isomers of (±)-5-(4-chlorophenyl)-1-(2,4- dichlorophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid morpholin-4-ylamide 9 with CB1 receptor in the homology model similar to those of N-piperidino-5-(4- chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide (rimonabant) 1 and 4S-(-)-3-(4-chlorophenyl)-N-methyl-N′-[(4-chlorophenyl) -sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine (SLV-319) 2.
- Srivastava, Brijesh Kumar,Joharapurkar, Amit,Raval, Saurin,Patel, Jayendra Z.,Soni, Rina,Raval, Preeti,Gite, Archana,Goswami, Amitgiri,Sadhwani, Nisha,Gandhi, Neha,Patel, Harilal,Mishra, Bhupendra,Solanki, Manish,Pandey, Bipin,Jain, Mukul R.,Patel, Pankaj R.
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p. 5951 - 5966
(2008/04/12)
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- Cationic rhodium(I)/bisphosphane complex-catalyzed isomerization of secondary propargylic alcohols to α,β-enones
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We have determined that hydrogenated cationic Rh(I)/bisphosphane complexes are highly active catalysts for the isomerization of secondary propargylic alcohols to α,β-enones. A kinetic resolution of secondary propargylic alcohols proceeded with moderate selectivity with [Rh((R)-BINA-P)]OTf as a catalyst. Mechanistic studies revealed that the isomerization proceeds through intramolecular 1,3- and 1,2-hydrogen migration pathways. The isomerization of propargylic diol derivatives was also investigated, which revealed that 1,4-diketones, furans, and α,β-enones were obtained from 2-butyn-1,4-diol, 1-methoxy-2-butyn-4-ol, and 1-acetoxy-2-butyn-4-ol derivatives, respectively. Furthermore, chemoselectivity of the isomerization of an acetylenic diol was investigated, and preferential oxidation of a propargylic hydroxy group was observed. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Tanaka, Ken,Shoji, Takeaki,Hirano, Masao
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p. 2687 - 2699
(2008/02/08)
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- Synthesis of 3-fluorofuran-2(5H)-ones based on Z/E photoisomerisation and cyclisation of 2-fluoro-4-hydroxybut-2-enoates
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Mixtures of some (E)- and (Z)-2-fluoroalk-2-enoates prepared from the corresponding 2-hydroxycarbonyl compounds and ethyl 2-(diethoxyphosphoryl)-2- fluoroacetate have been transformed in high conversions into the target 3-fluorofuran-2(5H)-ones by an effi
- Pomeisl, Karel,Cejka, Jan,Kvicala, Jaroslav,Paleta, Oldrich
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p. 5917 - 5925
(2008/04/13)
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- Deracemisation of aryl substituted α-hydroxy esters using Candida parapsilosis ATCC 7330: Effect of substrate structure and mechanism
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Candida parapsilosis ATCC 7330 was found to be an efficient biocatalyst for the deracemisation of aryl α-hydroxy esters (65-85% yield and 90-99% ee). A variety of aryl and aryl substituted α-hydroxy esters were synthesized to reflect steric and electronic effects on biocatalytic deracemisation. The mechanism of this biocatalytic deracemisation was found to be stereoinversion.
- Baskar,Pandian,Priya,Chadha, Anju
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p. 12296 - 12306
(2007/10/03)
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- An efficient synthesis of aryl α-keto esters
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A new one-pot approach for the synthesis of aryl α-keto ester based on the diazo transfer and oxidation of diazo group is developed.
- Ma, Ming,Li, Changkun,Peng, Lingling,Xie, Fang,Zhang, Xiu,Wang, Jianbo
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p. 3927 - 3929
(2007/10/03)
-
- A straighforward route to E-γ-aryl-α-oxobutenoic esters by one-step acid-catalysed crotonisation of pyruvates
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A new and highly simple method for the synthesis of E-γ-aryl-α-oxobutenoic esters is described. This unprecedented one-step procedure is based on an unexpected nucleophilic reactivity of alkyl pyruvates towards aromatic aldehydes in refluxing dichloromethane, when using catalytic amounts of Cu(OTf)2 and in the presence of stoichiometric amounts of trimethyl orthoformate in the case of electron-rich aldehydes. Under these conditions, yields obtained are uniformly higher than those obtained by previous multistep procedures.
- Dujardin,Leconte,Bénard,Brown
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p. 147 - 149
(2007/10/03)
-
- Enantioselective synthesis of dihydropyrans. Catalysis of hetero Diels - Alder reactions by bis(oxazoline) copper(II) complexes
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C2-symmetric bis(oxazoline) - Cu(II) complexes 1 and 2 catalyze the inverse electron demand hetero Diels - Alder reaction of α,β-unsaturated carbonyl compounds (heterodiene) with electron-rich olefins (heterodienophile) in high diastereo- and enantioselectivity, α,β- Unsaturated acyl phosphonates and β,γ-unsaturated α-keto esters and amides are effective heterodienes, while enol ethers and sulfides function as heterodienophiles. A range of substitution patterns is possible on the heterodiene: terminal alkyl, aryl, alkoxy, and thioether substituents are all tolerated. The enantioselective synthesis of dihydropyrans by this method has been shown to be straightforward: cycloadditions may be conducted with as little as 0.2 mol % of the chiral catalyst and are readily run on multigram scale. The reactions exhibit a favorable temperature - enantioselectivity profile, with selectivities exceeding 90% even at room temperature. A simple reaction protocol that employs a solid air-stable catalyst, convenient reaction temperatures, and low catalyst loadings is described. The utility of the derived cycloadducts in the preparation of chiral building blocks is demonstrated. Models for asymmetric induction are discussed considering product stereochemistry, X-ray crystallographic data for the solid catalysts, and mechanistic studies.
- Evans, David A.,Johnson, Jeffrey S.,Olhava, Edward J.
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p. 1635 - 1649
(2007/10/03)
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- Synthesis of β-Alkoxy Ketones and α′-Functionalized β-Alkoxy Ketones Utilizing Benzotriazole-Stabilized Acyl Anion Synthons
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1-(α-Alkoxyalkyl)benzotriazoles 1a-d add to phenyl vinyl ether to form key intermediates 4a-d, which readily undergo lithiation and subsequent trapping by a variety of electrophiles to give the expected substituted derivatives 7a-d, 9a-c, 11, 13, 15, and 18 in high yields. Subsequent hydrolysis of these compounds provides a novel high-yield acyl anion synthon approach for the synthesis of β-alkoxy ketones 8 or α′-functionalized β-alkoxy ketones 10, 12, 14, 16, and 19 by short procedures from readily available starting materials.
- Katritzky, Alan R.,Feng, Darning,Qi, Ming
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p. 1473 - 1477
(2007/10/03)
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- Hydrogenation of α-oxo carboxylic acid derivatives over nickel and palladium catalysts
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Hydrogenation of a number of α-oxo carboxylic acid derivatives over nickel catalysts and palladium black at 20-90°C has been studied. Hydrogenation of sodium 2-oxo-4-phenyl-3-butenoate over nickel catalysts results in reduction of the double bond and keto group to afford sodium 2-hydroxy-4-phenylbutanoate. Hydrogenation of the same substrate over palladium black can be stopped at the stage of formation of sodium 2-oxo-4-phenylbutanoate. Under similar conditions, ethyl 2,2-diethoxy-4-phenyl-3-butenoate shows a low reactivity. Sodium 2-oxo-4-(3-pyridyl)-3-butenoate is hydrogenated over palladium catalysts with formation of sodium 2-hydroxy-4-(3-pyridyl)-3-butenoate, whereas the reaction with analogous furan derivatives is accompanied by cleavage of the furan ring. One-step procedures have been developed for preparation of (9-fluorenyl)hydroxyacetic acid and 1-(9-fluorenyl)-1,2-ethanediol by hydrogenation of (9-fluorenyl)oxo-acetic acid (or its sodium salt) and methyl (9-ffuorenyl)oxoacetate, respectively. 1998 MAHK "Hayka/Interperiodica".
- Slavinskaya,Sile,Korchagova,Katkevich,Lipsbergs,Lukevits
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p. 1750 - 1754
(2007/10/03)
-
- Synthesis and reactivity of β-phenylselanyl α-oxoesters
-
β-Phenylsetanyl α-oxoesters 2 were prepared by N-phenylselanyl morpholine treatment of α-oxoesters 1, oxidized into β-unsaturated α- oxoesters 5 and subjected to the Wittig-Horner olefination. The diethyl (l- phenylselanylalkyl)maleates 6 have led, after [2,3]sigmatropic rearrangement of the corrsponding selenoxides to the diethyl 3-alkylidene-2- hydroxysuccinates 7. The 2-(1-butoxycarbonylamino)-3-alkylidenesuccinates 8 were prepared in a similar way. The decomposition of halo-adducts derived from components 6 has the synthesis of the siethyl 3-alkylidene-2- halosuccinates 9 and 10.
- Boivin, Stephane,Outurquin, Francis,Paulmier, Claude
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p. 16767 - 16782
(2007/10/03)
-
- RING-OPENING OF 4-ISOXAZOLINES: COMPETITIVE FORMATION OF ENAMINO DERIVATIVES AND α,β-ENONES
-
Ring-opening of 3-substituted 4-isoxazolines, proceeding through the intermediate isoxazolinium salts, follows two competing reaction pathways leading to α,β-enones and enamines respectively.The rearrangement courses can be controlled as a function of substitution pattern and experimental conditions.
- Chiacchio, Ugo,Casuscelli, Franco,Liguori, Angelo,Rescifina, Antonio,Romeo, Giovanni,et al.
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p. 585 - 600
(2007/10/02)
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- A New Synthetic Method for α-Oxo-β,γ-unsaturated Esters
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α-Oxo-β,γ-unsaturated esters have been prepared in moderate to good yields via a two-step procedure consisting of the boron trifluoride-promoted reaction of 2-(trimethylsiloxy)acrylic esters with acetals, followed by treatment with silics gel in benzene u
- Sugimura, Hideyuki,Yoshida, Kazuhiro
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p. 3209 - 3211
(2007/10/02)
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- Synthesis and Properties of Some 7-Dimethylamino-1,4-benzoxazin-2-ones
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The synthesis of the 7-dimethylamino-1,4-benzoxazin-2-ones (5), fluorescent dyes, by condensing α-ketoacids with 2-amino-5-dimethylaminophenol is described.When the 3-substituent is a methyl group, these compounds can be further condensed with aromatic aldehydes to provide the styryl dyes (6).These products are easily opened by hydrochloric acid in ethanolic solution to afford the corresponding benzalketoacid ethyl esters (7).
- Bris, Marie-Therese
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p. 1275 - 1280
(2007/10/02)
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- NAD(P)H MODELS 20 CHEMOSELECTIVE METAL ION CATALYZED REDUCTION OF α-KETO-β,γ-UNSATURATED ESTERS BY 1,4-DIHYDROPYRIDINE DERIVATIVES
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Ethyl 2-oxo-4-aryl-3-butene-1-oates (1a-c) are reduced by NAD(P)H models (1-n-propyl-1,4-dihydronicotinamide (4) and Hantzsch ester (5)), in presence of magnesium perchlorate.One equivalent of the reductant reduces the substrates selectively to the corresponding 2-oxo-4-arylbutanoates (6, 10a, b).An additional equivalent and higher temperature, converts ethyl 2-oxo-4-phenylbutanoate (6) to ethyl 2-hydroxy-4-phenylbutanoate (7).Reduction of ethyl 2-oxo-4-phenyl-3-buten-1-oate (1a) by Hantzsch ester in C2H5OD or by Hantzsch ester-4,4-d2 in C2H5OH, leads to direct transfer of the hydrogen or deuterium, respectively, without isotopic scrambling.These results have been interpreted to support the hydride transfer mechanism.
- Meijer, Louis H. P.,Pandit, Upendra K.
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p. 467 - 472
(2007/10/02)
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