- Bimetallic Phase Transfer Catalysis
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γ-Keto acids are obtained by the phase transfer catalysed reaction of alkynes with carbon monoxide and methyl iodide in the presence of catalytic amounts of cobalt and ruthenium carbonyl complexes.
- Alper, Howard,Petrignani, Jean-Francois
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- Practical synthesis of diethyl phenylsuccinate by Mg-promoted carboxylation of ethyl cinnamate
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Mg-promoted reduction of ethyl cinnamate (1a) in the presence of carbon dioxide gave a mixture of β-carboxylated compound 2a and α,β-dicarboxylated compound 3a. Similar reductive carboxylation of 1a followed by acidic decarboxylation of one of the two geminal carboxyl groups of the generated 3a and esterification afforded selective formation of diethyl phenylsuccinate (2a) in good yield.
- Maekawa, Hirofumi,Murakami, Taro,Miyazaki, Takeshi,Nishiguchi, Ikuzo
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supporting information; experimental part
p. 368 - 369
(2011/05/04)
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- Formation of γ-oxoacids and 1 H-pyrrol-2(5 H)-ones from α,β-unsaturated ketones and ethyl nitroacetate
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Michael addition of ethyl nitroacetate on α,β-unsaturated ketones followed by Nef oxidation under hydrolytic conditions yields γ-oxoacids instead of the corresponding α,δ-dioxoesters. A concerted decarboxylation step is proposed on the basis of computational results. Finally, conversion of the γ-ketoacids thus prepared into 1H-pyrrol-2(5H)-ones by reaction with primary amines under Paal-Knorr conditions is also reported.
- Aginagalde, Maialen,Bello, Tamara,Masdeu, Carme,Vara, Yosu,Arrieta, Ana,Cossio, Fernando P.
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experimental part
p. 7435 - 7438
(2010/12/25)
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- Au2O3 as a stable and efficient catalyst for the selective cycloisomerization of γ-acetylenic carboxylic acids to γ-alkylidene-γ-butyrolactones
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The high potential of commercially available Au2O3 as a catalyst in the cyclization of alkynes bearing carboxylic acids to the corresponding γ-alkylidene-γ-butyrolactones through a general, efficient and easy procedure is presented. The reaction shows a high degree of chemo-, regio-, and stereoselectivity. The 5-exo mode of cyclization and anti auration are a general trend for the Au2O3 catalyst. Georg Thieme Verlag Stuttgart.
- Toullec, Patrick Yves,Genin, Emilie,Antoniotti, Sylvain,Genêt, Jean-Pierre,Michelet, Véronique
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p. 707 - 711
(2008/12/21)
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- Predominant 1,2-insertion of styrene in the Pd-catalyzed alternating copolymerization with carbon monoxide
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The regioselectivity of styrene insertion to an acyl-Pd bond was studied by NMR in (i) a stoichiomeric reaction and (ii) a copolymerization with CO. In the stoichiometric reaction of styrene with [(CH3CO)Pd-(CH3CN){(R,S)-BINAPHOS}] ·[B{3,5-(CF3)2C6 H3}4], both 1,2-and 2,1-products were given. To mimic the real polymerization conditions, a polyketone-substituted complex [{CH3(CH2CHCH3CO)n}Pd{(R,S)-BINAP HOS}]·[B(3,5-(CF3)2C6 H3)4] (n ≈ 14) was prepared. When this polymer-attached Pd species was treated with styrene, the 1,2-insertion product was the only detectable species. Thus, exclusive 1,2-insertion is demonstrated to be responsible for the styrene-CO copolymerization, in sharp contrast to the predominant 2,1-insertion with conventional nitrogen ligands. Chain-end analysis revealed that β-hydride elimination took place from the 2,1-complex but not from the 1,2-complex. Thus, once 2,1-insertion occurs, rapid β-hydride elimination proceeds to terminate the polymerization, as is common to the other phosphorus-ligand systems. The resulting Pd-H species re-initiates the copolymerization, as was proven by MALDI-TOF mass analysis of the product copolymers.
- Nozaki,Komaki,Kawashima,Hiyama,Matsubara
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p. 534 - 544
(2007/10/03)
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- A new chiral alkylation methodology for the synthesis of 2-alkyl-4-ketoacids in high optical purity using 2-triflyloxy esters
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Optical active 2-triflyloxy esters are excellent alkylating agents for β-ketoester enolates. Decarboxylation of the alkylation products gives 2-substituted-4-ketoacid derivatives in high optical purities.
- Hoffman, Robert V.,Kim, Hwa-Ok
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p. 2051 - 2054
(2007/10/02)
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- Chemoselectivity of rhodium carbenoids. A comparison of the selectivity for O-H insertion reactions or carbonyl ylide formation versus aliphatic and aromatic C-H insertion and cyclopropanation
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A range of diazocarbonyl compounds 1-9 containing two different functional groups has been prepared, and their rhodium(II) catalysed decomposition studied as a means of probing the chemoselectivity of carbenoid intermediates. The results indicate that wereas O-H insertion reactions predominate over cyclopropanation and aromatic insertion reactions, carbonyl ylide formation vs other competing processes is more finely balanced, and is catalyst dependent.
- Cox,Moody,Austin,Padwa
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p. 5109 - 5126
(2007/10/02)
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- Electrocarboxylation de composes carbonyles aliphatiques, aromatiques et vinyliques: interet de l'utilisation d'une anode consommable en magnesium
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In the presence of carbon dioxide in DMF, the electroreduction of carbonyl compounds or α,β-ketoalkenes at high concentration yields respectively α-hydroxyacids and β-ketoacids.The use of a sacrificial magnesium anode allows constant current electrolyses in a diaphragmless cell.
- Mcharek, Slah,Heintz, Monique,Troupel, Michel,Perichon, Jacques
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- Reactions of Ketenes. XX. Phenylketene Dimethylacetal As Synthon For the Introduction of Functionalized Phenylethyl Units
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Phenylketene dimethylacetal (1) reacts with the α-diazoketones to give the dihydrofurans 6.These compounds, as cyclic ortho esters, can undergo dealcoholation into the furans 2 and hydrolysis into the γ-ketoesters 3 and into the γ-ketoacids 4.Cyclopropane acetal 8, obtained starting from acetal 1 and ethyl diazoacetate, by heating leads quantitatively to functionalized ester 9.These synthetic methods enlarge the sphere of applicability of the electron-rich alkene 1 as synthon in organic synthesis.
- Graziano, Liliana M.,Iesce, Rosaria M.,Scarpati, Rachele
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p. 553 - 556
(2007/10/02)
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- Michael Reaction of Conjugated Nitro Olefins with Carboxylic Acid Dianions and with Ester Enolates: New Synthesis of γ-Keto Acids and γ-Keto Esters
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Base-sensitive conjugated nitro olefins 2 reacted with lithium dianions of carboxylic acids 3 or with lithium enolates of esters 4 at a low temperature of ca. -100 deg C, and subsequent treatment of the Michael adducts with aqueous acid yielded γ-keto acids 5 or esters 5' in a one-pot operation, respectively.Results of both the reactions have been compared.Some applications of the resulting γ-keto esters in organic synthesis have also been demonstrated in lactone synthesis and cyclenone annulation.
- Miyashita, Masaaki,Yamaguchi, Ryuji,Yoshikoshi, Akira
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p. 2857 - 2863
(2007/10/02)
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- ELECTROCHEMICAL CARBOXYLATION OF alpha , beta -UNSATURATED KETONES WITH CARBON DIOXIDE.
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Several aromatic and aliphatic alpha , beta -unsaturated ketones were converted to the corresponding gamma -keto acids by the electrochemical reduction in acetonitrile in the presence of CO//2. The yields of the keto acid were 73-82% when the enones have at least one aromatic substituent. In the case of aliphatic enones, the yields of the carboxylation reaction were 67% for 2-cyclohexen-1-one and 44% for 3-buten-2-one.
- Harada,Sakakibara,Kunai,Sasaki
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p. 611 - 612
(2007/10/02)
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- NEW SYNTHESIS OF Γ-KETO ACIDS FROM NITROOLEFINS AND CARBOXYLIC ACID DIANIONS
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As a convenient synthetic method of γ-keto acids, oxoalkylation of carboxylic acids with nitroolefins was examinated.Carboxylic acid dianions reacted with conjugated nitroolefins at low temperature (-100 deg C) and a variety of γ-keto acids were obtained on acidic workup in moderate to good yields.
- Miyashita, Masaaki,Yamaguchi, Ryuji,Yoshikoshi, Akira
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p. 1505 - 1508
(2007/10/02)
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- RING OPENING REACTION OF gem-DIFLUOROCYCLOPROPYL KETONES WITH NUCLEOPHILES
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Syntheses of gem-difluorocyclopropyl ketones (3a-d) and their reactions with nucleophiles are described.Ring opening reactions of 3a, c and d with a methanolate and a thiolate anion took entirely different courses of bond scission of the cyclopropane ring.
- Kobayashi, Yoshiro,Taguchi, Takeo,Morikawa, Tsutomu,Takase, Toyohiko,Takanashi, Hiroshi
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p. 1047 - 1050
(2007/10/02)
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