- Synergistic N-Heterocyclic Carbene/Palladium-Catalyzed [3 + 2] Annulation of Vinyl Enolates with 1-Tosyl-2-vinylaziridine
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The synergistic combination of N-heterocyclic carbene organocatalysis and transition-metal catalysis for a formal [3 + 2] annulation between 3-substituted but-2-enoates and 1-tosyl-2-vinylaziridine was developed. This cooperative strategy provides a facile and efficient access to various functionalized (E)-3-ethylidene-4-vinylpyrrolidin-2-ones in a regioselective and stereoselective manner. The preliminary asymmetric studies were also performed, which indicated a potential for enantioselective annulation of vinyl enolate intermediates with transition-metal-π-allyl species.
- Gao, Jian,Zhang, Jianming,Fang, Shuaishuai,Feng, Jie,Lu, Tao,Du, Ding
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p. 7725 - 7729
(2020/10/09)
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- Construction of Multi-Substituted Benzenes via NHC-Catalyzed Reactions of Carboxylic Esters
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A carbene-catalyzed ester activation reaction for the synthesis of multi-substituted benzenes is developed. Tetra-substituted benzene compounds are efficiently synthesized through this methodology. Compared with aldehyde substrates used in previous reports, the ester substrates used here are much more readily available and inexpensive. In addition, the TEMPO oxidant used here is more inexpensive than the quinones commonly used in related carbene-catalyzed reactions.
- Wu, Jichang,Mou, Chengli,Chi, Yonggui Robin
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p. 333 - 337
(2018/03/07)
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- Synthesis of 6-hydroxy-5,6-dihydro-2-pyrones and -pyridones by reaction of 4-aryl-6-trifluoromethyl-2-pyrones with water, hydrazine, and hydroxylamine
-
[Figure not available: see fulltext.] Reactions of 4-aryl-6-trifluoromethyl-2H-pyran-2-ones with sodium hydroxide followed by acidification provided the respective 6-hydroxy-5,6-dihydro derivatives, while the reactions of 4-aryl-6-trifluoromethyl-2H-pyran
- Usachev, Sergey A.,Usachev, Boris I.,Sosnovskikh, Vyacheslav Ya.
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p. 1294 - 1301
(2018/01/27)
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- Iridium(III)-catalyzed regioselective direct arylation of sp2 C-H bonds with diaryliodonium salts
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A regioselective direct arylation of arenes and olefins at the ortho position is reported. The key to the high selectivity is the appropriate choice of diaryliodonium salts as the arylating reagent in the presence of a cationic iridium(iii) catalyst. The coordination of the metal with an oxygen atom or a nitrogen atom and subsequent C-H activation allows for direct arylation with coupling partners. This reaction proceeds under mild reaction conditions and with a high tolerance of various functional groups including many halide functional groups.
- Gao, Pan,Liu, Li,Shi, Zhuangzhi,Yuan, Yu
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p. 7109 - 7113
(2016/07/30)
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- One Photocatalyst, n Activation Modes Strategy for Cascade Catalysis: Emulating Coumarin Biosynthesis with (-)-Riboflavin
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Generating molecular complexity using a single catalyst, where the requisite activation modes are sequentially exploited as the reaction proceeds, is an attractive guiding principle in synthesis. This requires that each substrate transposition exposes a catalyst activation mode (AM) to which all preceding or future intermediates are resistant. While this concept is exemplified by MacMillan's beautiful merger of enamine and iminium ion activation, examples in other fields of contemporary catalysis remain elusive. Herein, we extend this tactic to organic photochemistry. By harnessing the two discrete photochemical activation modes of (-)-riboflavin, it is possible to sequentially induce isomerization and cyclization by energy transfer (ET) and single-electron transfer (SET) activation pathways, respectively. This catalytic approach has been utilized to emulate the coumarin biosynthesis pathway, which features a key photochemical E → Z isomerization step. Since the ensuing SET-based cyclization eliminates the need for a prefunctionalized aryl ring, this constitutes a novel disconnection of a pharmaceutically important scaffold.
- Metternich, Jan B.,Gilmour, Ryan
-
supporting information
p. 1040 - 1045
(2016/02/05)
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- Pd-Catalyzed α-Selective C-H Functionalization of Olefins: En Route to 4-Imino-β-Lactams
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Pd-catalyzed α-olefinic C-H activation of simple α,β-unsaturated olefins has been developed. 4-imino-β-lactam derivatives were readily synthesized via activation of α-olefinic C-H bonds with excellent cis stereoselectivity. A wide range of heterocycles at the β-position are compatible with this reaction. The product of 4-imino-β-lactam derivatives can be readily converted to 2-aminoquinoline which exists extensively in pharmaceutical drugs and natural products.
- Kong, Wei-Jun,Liu, Yue-Jin,Xu, Hui,Chen, Yan-Qiao,Dai, Hui-Xiong,Yu, Jin-Quan
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p. 2146 - 2149
(2016/03/05)
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- Metal-Free Domino One-Pot Decarboxylative Cyclization of Cinnamic Acid Esters: Synthesis of Functionalized Indanes
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Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid triggered decarboxylation of cinnamic acid esters and subsequent inter/intramolecular cyclization. Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter/intramolecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the aid of any metal salts.
- Gopi Krishna Reddy, Alavala,Satyanarayana, Gedu
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p. 12212 - 12222
(2016/12/23)
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- N-Heterocyclic Carbene-Catalyzed Activation of Esters of N-Hydroxyphthalimide: A Highly Enantioselective Route to Chiral Dihydropyridinones Bearing an All Carbon Quaternary Stereogenic Center
-
An N-heterocyclic carbene-catalyzed highly enantioselective [3 + 3] annulation reaction of N-hydroxyphthalimide (NHPI) 3,3-disubstituted acrylates and N-Ts ketimines was developed. In most cases, the desired chiral dihydropyridinone products bearing an all carbon quaternary stereogenic center could be obtained in good yields with excellent enantioselectivities (>99% ee's), which demonstrated the NHPI acrylates as a kind of excellent substrate in NHC-catalysis.
- Zhang, Zhiming,Zeng, Xiaofei,Xie, Danbo,Chen, Dongdong,Ding, Liyuan,Wang, Anna,Yang, Limin,Zhong, Guofu
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p. 5052 - 5055
(2015/11/03)
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- Synthesis of coumarins via PIDA/I2-mediated oxidative cyclization of substituted phenylacrylic acids
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A variety of functionalized coumarins were synthesized from substituted phenylacrylic acids via PIDA/I2-mediated and irradiation-promoted oxidative carbon-oxygen bond formation. Our studies show that the oxygen in the pendant carboxylic acid group cyclizes favorably to the aryl ring that is cis to it. The main advantages of this method include good functional group tolerance and the transition-metal-free characteristic. The Royal Society of Chemistry 2013.
- Li, Jinming,Chen, Huiyu,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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p. 4311 - 4320
(2013/04/24)
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- Organocatalytic enantioselective γ-aminoalkylation of unsaturated ester: Access to pipecolic acid derivatives
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The direct γ-carbon functionalization of α,β-unsaturated esters via N-Heterocyclic Carbene (NHC) catalysis is disclosed. This catalytically generated nucleophilic γ-carbon undergoes highly enantioselective additions to hydrazones. The resulting δ-lactam products can be readily transformed to optically enriched pipecolic acid derivatives.
- Xu, Jianfeng,Jin, Zhichao,Chi, Yonggui Robin
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p. 5028 - 5031
(2013/10/22)
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- Key structural features of cis-cinnamic acid as an allelochemical
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1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
- Abe, Masato,Nishikawa, Keisuke,Okuda, Katsuhiro,Shindo, Mitsuru,Fukuda, Hiroshi,Nakanishi, Kazunari,Tazawa, Yuta,Taniguchi, Tomoya,Park, So-Young,Hiradate, Syuntaro,Fujii, Yoshiharu
-
p. 56 - 67,12
(2012/12/12)
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- Ruthenium-catalyzed asymmetric transfer hydrogenation of allylic alcohols by an enantioselective isomerization/transfer hydrogenation mechanism
-
Reducing hazards: A asymmetric transfer hydrogen reaction was developed to reduce prochiral allylic alcohols in high yield and excellent enantioselectivity (see example). Mechanistic studies indicate a novel enantioselective isomerization/transfer hydrogenation mechanism. This new reaction is much safer than high-pressure hydrogenation using H2 gas. Copyright
- Wu, Ruoqiu,Beauchamps, Marie G.,Laquidara, Joseph M.,Sowa Jr., John R.
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supporting information; experimental part
p. 2106 - 2110
(2012/04/11)
-
- N-heterocyclic carbene-catalyzed cyclization of unsaturated acyl chlorides and ketones
-
A straightforward synthesis of optically active trifluoromethyl dihydropyranones and spirocyclic oxindole-dihydropyranones has been realized by the chiral N-heterocyclic carbenes-catalyzed cyclization of α,β- unsaturated β-methylacyl chlorides with activated trifluoromethyl ketones or isatin derivatives. Copyright
- Shen, Li-Tao,Shao, Pan-Lin,Ye, Song
-
p. 1943 - 1948
(2011/10/13)
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- Catalytic enantioselective construction of β-quaternary carbons via a conjugate addition of cyanide to β,β-disubstituted α,β-unsaturated carbonyl compounds
-
The first general catalytic enantioselective conjugate addition of cyanide to β, β-disubstituted α,β-unsaturated ketones and N-acylpyrroles was developed using a strontium catalyst derived from Sr(O iPr)2 and new chiral ligand 5. The reaction exhibited excellent enantioselectivity and a wide substrate scope using 0.5-10 mol % catalyst. 1,4-Adducts containing β-quaternary carbons were exclusively produced over 1,2-adducts. ESI-MS analysis of the strontium catalyst indicated that the active catalyst was a trimetallic Sr/5 = 3:5 complex. The exclusive 1,4-selectivity was partly due to the ability of the strontium complex to promote both a retro-cyanation reaction from the 1,2-adducts and highly enantioselective conjugate cyanation.
- Tanaka, Yuta,Kanai, Motomu,Shibasaki, Masakatsu
-
supporting information; experimental part
p. 8862 - 8863
(2010/08/21)
-
- Catalytic asymmetric formation of δ-Lactones from Unsaturated acyl halides
-
Previously unexplored enantiopure zwitterionic ammonium dienolates have been utilized in this work as reactive intermediates that act as diene components in hetero-Diels-Alder reactions (HDAs) with aldehydes to produce optically active δ-lactones, subunits of numerous bioactive products. The dienolates were generated in situ from E/Z mixtures of a,b- unsaturated acid chlorides by use of a nucleophilic quinidine derivative and Sn (OTf)2 as co-catalyst. The latter component was not directly involved in the cycloaddition step with aldehydes and simply facilitated the formation of the reactive dienolate species. The scope of the cycloaddition was considerably improved by use of a complex formed from Er- (OTf)3 and a simple commercially available norephedrine-derived ligand that tolerated a broad range of aromatic and heteroaromatic aldehydes for a cooperative bifunctional Lewis-acid-/ Lewis-base-catalyzed reaction, providing a,b-unsaturated d-lactones with excellent enantioselectivities. Mechanistic studies confirmed the formation of the dienolate intermediates for both catalytic systems. The active ErIII complex is most likely a monomeric species. Interestingly, all lanthanides can catalyze the title reaction, but the efficiency in terms of yield and enantioselectivity depends directly on the radius of the Ln III ion. Similarly, use of the pseudolanthanides ScIII and YIII also resulted in product formation, whereas the larger La III and other transition metal salts, as well as main group metal salts, proved to be inefficient. In addition, various synthetic transformations of 6- CCl3- or 4-silyl-substituted α,β-unsaturated d-lactones, giving access to a number of valuable δ-lactone building blocks, were investigated.
- Tiseni, Paolo S.,Peters, Rene
-
supporting information; experimental part
p. 2503 - 2517
(2010/09/03)
-
- Catalytic asymmetric formation of δ-lactones by [4+2] cycloaddition of zwitterionic dienolates generated from α,β-unsaturated acid chlorides
-
Smooth elaboration: Versatile δ-lactone building blocks are provided by tertiary amine-catalyzed asymmetric [4+2] cycloadditions of α,β-unsaturated acid chlorides and the electron-poor aldehyde chloral (see scheme). Silyl-substituted acid chlorides (R1 = R 3Si) can be used for the diastereoselective synthesis of β-hydroxy-δ-lactones possessing quaternary stereocenters. (Chemical Equation Presented).
- Tiseni, Paolo S.,Peters, Rene
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p. 5325 - 5328
(2008/03/18)
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- Two-carbon homologation of ketones via sily ketene acetals: Synthesis of α,β-unsaturated acids and α-trimethylsilyl δ-ketoacids
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The reaction of C,O,O-tris(trimethylsilyl)ketene acetal 1 with saturated, cyclic and aromatic ketones 2 proceeds smoothly in the presence of titanium chloride to give (E)-α,β-unsaturated carboxylic acids 3 with fairly good stereoselectivity. With α,β-unsa
- Bellassoued, Moncef,Mouelhi, Sinda,Fromentin, Pierre,Gonzalez, Aurélien
-
p. 2172 - 2179
(2007/10/03)
-
- N-azabicyclo-amide derivatives
-
Compounds of the general formula I wherein A represents: D represents oxygen, or sulfur and R1, R2and R3are as defined in the specification, enantiomers thereof, pharmaceutically-acceptable salts thereof, processes for preparing them, pharmaceutical compositions containing them and their use in therapy, especially in the treatment or prophylaxis of psychotic disorders and intellectual impairment disorders.
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-
Page column 20
(2010/02/05)
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- Mizoroki-Heck arylation of α,β-unsaturated acids with a hybrid fluorous ether, F-626: Facile filtrative separation of products and efficient recycling of a reaction medium containing a catalyst
-
The Mizoroki-Heck reaction was carried out using a fluorous ether F-626 as the solvent and a fluorous Pd carbene complex as the catalyst. When carboxylic acids are the products, separation of both the F-626 and the Pd catalyst from the products can be conveniently carried out by simple filtration. The F-626 filtrates containing the Pd catalyst can be recycled.
- Fukuyama, Takahide,Arai, Masashi,Matsubara, Hiroshi,Ryu, Ilhyong
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p. 8105 - 8107
(2007/10/03)
-
- (E)-Selective Horner-Wadsworth-Emmons reaction of aryl alkyl ketones with bis(2,2,2-trifluoroethyl)phosphonoacetic acid
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The stereoselective Horner-Wadsworth-Emmons reaction of aryl alkyl ketones with bis(2,2,2-trifluoroethyl)phosphonoacetic acid utilizing lithium hexamethyldisilazide in DMF afforded (E)-α,β-unsaturated carboxylic acids as the major products.
- Sano, Shigeki,Takemoto, Yuka,Nagao, Yoshimitsu
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p. 8853 - 8855
(2007/10/03)
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- Palladium-catalysed cross-coupling of iodovinylic acids with organometallic reagents. Selective synthesis of 3,3-disubstituted prop-2-enoic acids
-
3,3-Disubstituted prop-2-enoic acids were selectively prepared in good yields under mild experimental conditions via palladium-catalysed cross-coupling of 3-substituted 3-iodobut-2-enoic acids with miscellaneous organometallic reagents using dichlorobis(acetonitrile)palladium(II) as catalyst and DMF as solvent.
- Abarbri, Mohamed,Thibonnet, Jér?me,Parrain, Jean-Luc,Duchêne, Alain
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p. 543 - 551
(2007/10/03)
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- Highly efficient enantioselective synthesis of optically active carboxylic acids by Ru(OCOCH3)2[(S)-H8-BINAP]
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In the presence of a catalytic amount of Ru(OCOCH3)2[(S)-H8-BINAP] [H8-BINAP = 2,2′-bis-(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′- octahydro-1,1′-binaphthyl], the asymmetric hydrogenation of α,β- and β,γ-unsaturated carboxylic acids afforded the corresponding saturated carboxylic acids in higher enantiomeric excesses and at faster reaction rates than those using the Ru(OCOCH3)2[(R)-BINAP] catalyst [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl]. The hydrogenation of (E)-2-alkyl-2-alkenoic acids by the H8-BINAP catalyst system produced saturated acids in 95-97% ee. 2-Methylcinnamic acid was treated with H8-BINAP-Ru(II) complex as a catalyst to yield a hydrogenated product in much higher ee than that produced by BINAP-Ru(II) (89 and 30% ee, respectively). This homogeneous catalysis using H8-BINAP-Ru(II) established a promising synthetic route to (S)-ibuprofen in up to 97% ee. Asymmetric hydrogenation of β-disubstituted acrylic acids also proceeded smoothly with good enantioselectivities (70-93% ee). In addition, the hydrogenation of trisubstituted acrylic acids (up to 88% ee) was investigated. Hydrogen pressure effect on the sense and level of enantioselection was shown to be substrate dependent. The difference between the H8-BINAP- and BINAP-Ru(II) complexes was also discussed.
- Uemura, Toshitsugi,Zhang, Xiaoyoung,Matsumura, Kazuhiko,Sayo, Noboru,Kumobayashi, Hidenori,Ohta, Tetsuo,Nozaki, Kyoko,Takaya, Hidemasa
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p. 5510 - 5516
(2007/10/03)
-
- Stereospecific synthesis of (Z) or (E)-3-methylalk-2-enoic acids
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The palladium catalysed coupling of organozinc or organotin reagents with 3-iodobut-2(or 3)-enoic acid is stereoselective and affords Z (or E)-3-methylalk-2-enoic acids. The method was applied to the synthesis of the E and Z stereoisomers of ocimenones and pseudo-tagetones.
- Abarbri,Parrain,Duchene
-
p. 2469 - 2472
(2007/10/02)
-
- Enantioselective Conjugate Reduction of α,β-Unsaturated Carboxamides with Semicorrin Cobalt Catalysts
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Chiral semicorrin cobalt complexes, prepared in situ from cobalt(II) chloride and the free ligands, are efficient, highly enantioselective catalysts for the conjugate reduction of α,β-unsaturated carboxamides with sodium borohydride.Enantiomeric excesses of up to 99percent, essentially quantitative yields, and high substrate/catalyst ratios (1000-10 000:1) are attractive attributes of this catalytic process.
- Matt, Peter von,Pfaltz, Andreas
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p. 691 - 700
(2007/10/02)
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- Carbonylation of Vinyl Halides with Carbonylcobalt
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The reactions of both (E)-β-bromostyrene (E)-(1a) and its Z-isomer (Z)-(1a) with octacarbonyldicobalt in the presence of methyl iodide and calcium hydroxide at 20 deg C in dioxane-water under carbon monoxide (1 atm) gave (E)-cinnamic acid (E)-(2a) exclusively.In contrast, with (E)-1-bromo-2-phenylpropene (E)-(1b), the thermodynamically less stable (Z)-3-phenylbut-2-enoic acid (Z)-(2b) was obtained as the major product together with the (E)-isomer (E)-(2b).The carbonylation of 3-chloroprop-2-enols (7a-f) gave the corresponding furan-2(5H)-ones (8a-f) in good yield.
- Miura, Masahiro,Okuro, Kazumi,Hattori, Ayako,Nomura, Masakatsu
-
-
- Straightforward Synthesis of 2-Alkenoic Acids from the Corresponding Saturated Aldehydes
-
2-Alkenoic acids may be prepared in good yields from saturated aldehydes via α-selenenylation with 4-(phenylseleno)morpholine formed in situ, followed by hydrogen peroxide oxidation.The actual oxidizing agent is benzeneperseleninic acid which is formed in the reaction medium.
- Outurquin, Francis,Paulmier, Claude
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p. 690 - 691
(2007/10/02)
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- Reaction of α-Substituted β-Bromostyrenes with Dicarbonyldicyanonickelate(0) Anion in Alkaline Medium under Carbon Monoxide
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The reactions of (E)- and (Z)-β-bromostyrene (1a) with dicarbonyldicyanonickelate(0) anion generated in situ in the presence of sodium or calcium hydroxide under carbon monoxide gave a carbonylated product mixture of (E)-cinnamic acid , 3,4-diphenylhexanedioic acid (4), and 3-phenylpropionic acid (5).In contrast, in the reactions of α-methyl- and phenyl-β-bromostyrenes (1b and c) the corresponding nitriles (3b and c) were formed, together with the carboxylic acids (2b and c).
- Miura, Masahiro,Shimoura, Nobuhiro,Nomura, Masakatsu
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p. 1993 - 1996
(2007/10/02)
-
- Photocarboxylation in the Presence of Aromatic Amines and Carbon Dioxide
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Phenylethylenes (1), biphenyl, and 1-methyl-2-phenylindole underwent carboxylation upon photolysis in the presence of aromatic amines (2) and carbon dioxide.
- Ito, Yoshikatsu,Uozu, Yoshihiro,Matsuura, Teruo
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p. 562 - 564
(2007/10/02)
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- Carbonylation of Aryl Halides and Vinyl Bromides Mediated by Tetracarbonylcobalt Anion
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The reaction of aryl halides (1a-g) with octacarbonyldicobalt in the presence of methyl iodide and sodium hydroxide under phase-transfer conditions was found to give a mixture of aryl methyl ketones (2a-g) and aromatic carboxylic acids (3a-h).From vinyl halides (9a-c), however, the corresponding carboxylic acids (10a-c) were obtained exclusively.
- Miura, Masahiro,Akase, Fumiaki,Shinohara, Masato,Nomura, Masakatsu
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p. 1021 - 1026
(2007/10/02)
-
- N.M.R. Spectra of the β-Methylcinnamic Acids and Their Methyl Esters
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The configurations of the (E)- and (Z)-β-methylcinnamic acids and their methyl esters have been confirmed by 1H and 13C n.m.r.spectroscopy.
- Shoppee, Charles W.,Brownlee, Robert T. C.
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p. 1557 - 1559
(2007/10/02)
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- Asymmetric hydrogenation of β - methylcinnamates of phenylalkylmethanols. Catalyst-phenyl groups interactions in the preferred adsorption conformation
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The β-methylcinnamates of four S-alkylphenylmethanols have been hydrogenated on Pt catalyst. The observed asymmetric inductions suggest that simultaneous bonded interactions of both the phenyl groups with the catalyst in the transition states do not occur.
- Gallina, Carlo,Lucente, Gino,Pinnen, Francesco
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p. 2361 - 2363
(2007/10/06)
-