- CuCN catalyzed one pot synthesis of γ-keto diesters: Domino double Michael addition followed by Nef reaction
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An efficient one pot synthesis of γ-keto diesters through double Michael addition coupled with Nef reaction in the presence of CuCN catalyst and Cs2CO3 base is described. The reaction proceeds rapidly in DCM to give the products in good yields. A plausible mechanism is proposed.
- Farooq, Saleem,Sangwan, Payare L.,Aleti, Rajeshwar R.,Chinthakindi, Praveen K.,Qurishi, Mushtaq A.,Koul, Surrinder
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supporting information; experimental part
p. 3305 - 3309
(2012/08/07)
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- Niobium pentachloride-mediated novel homologation reactions using α-trialkylstannylmethyl-β-keto esters
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In the presence of niobium pentachloride (NbCl5), an α-trialkylstannylmethyl-β-keto ester is homologated to the corresponding γ-keto ester in good yield; the reaction mechanism is discussed.
- Yamamoto, Makoto,Nakazawa, Misako,Kishikawa, Keiki,Kohmoto, Shigeo
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p. 2353 - 2354
(2007/10/03)
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- Unsymmetrical Ketone Synthesis via a Three-Component Connection Reaction of Organozincs, Allylating Agents, and Carbon Monoxide
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A wide variety of organozincs (diethylzinc, alkylzinc halides, and organozincs 2, 5, and 9a-e, functionalized with ester and nitrile groups) undergo a three-component connection reaction with carbon monoxide and allylic benzoates or phosphates 1a-h to furnish unsymmetrical ketones, e.g., 3, 6, and 10, in good yields uder 1 atm of carbon monoxide at ambient temperature by the catalysis of tetrakis(triphenylphosphine)palladium in THF/HMPA.The regio- and stereoselectivities of the present carbonylation show marked contrast to those reported for the palladium-catalyzed carbonylation of usymmetrical allylic substrates.For example, the reaction of crotyl benzoate with octylzinc iodide provides all the possible stereo- and regioisomers, i.e., cis- and trans-2-butenyl and 1-methyl-2-propenyl octyl ketones in comparable amounts.The carbonylative coupling of carvyl phosphates, trans- and cis-1h, and γ-zincio ester 5 is stereospecific and proceeds with inversion of configuration at the allylic stereocenters to furnish cis- and trans-6h, respectively, as single diastereomers.In the absence of HMPA, the reaction feature changes dramatically and lactones 12 and 13 (composed of organozincs, carbon monoxide, and allylating agents in the ratios of 1:1:2 and 2:1:1, respectively) and symmetrical keto diesters 14 (composed of 2 mol of organozincs and 1 mol of carbon monoxide) are formed in varying ratios depending on the reaction conditions.Synthetic scope of the unsymmetrical ketones and mechanistic rationale for these unique and unprecedented reaction behaviors are discussed.
- Yasui, Kengo,Fugami, Keigo,Tanaka, Shuji,Tamaru, Yoshinao
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p. 1365 - 1380
(2007/10/02)
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- Synthesis of 1,4-dicarbonyl compounds and 4-keto pimelates by palladium-catalyzed carbonylation of siloxycyclopropanes
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Palladium-catalyzed reaction of a siloxycyclopropane with an aryl triflate under carbon monoxide pressure (10-20 atm) in HMPA and that with carbon monoxide in chloroform provides new synthetic routes to 1,4-dicarbonyl compounds and 4-keto pimelates, respectively. The reaction of a siloxycyclopropane with a vinyl triflate, on the other hand, gives an acyloxycyclopropane instead.
- Aoki,Nakamura
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p. 3935 - 3946
(2007/10/02)
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- Lipase-Catalyzed Preparation of Optically Active γ-Butyrolactones in Organic Solvents
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Lipases in anhydrous organic solvents catalyze the lactonization of esters of γ-hydroxy carboxylic acids with a high degree of stereospecifity.Under these conditions the lipases exhibit both enantioselectivity and prochiral selectivity.We exploited the enzymes' enantioselectivity for synthesis of chiral lactones from racemic γ-hydroxy esters and their prochiral stereospecifity, i.e. the ability to discriminate between enantiotopic groups of a prochiral molecule, for the enantioconvergent lactonization of symmetrical γ-hydroxy diesters.This approach was used to develop a convenient, high yielding, and stereoselective route to several optically active γ-substituted γ-butyrolactones.
- Gutman, Arie L.,Zuobi, Kheir,Bravdo, Tamar
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p. 3546 - 3552
(2007/10/02)
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- The reaction of potassium tetracarbonylhydridoferrate with ethyl acrylate in ethanol
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The reaction of KHFe(CO)4 with an excess of ethyl acrylate in ethanol for 30 h at 70 deg C leads to ethyl propyonate (270percent with respect to iron) and diethyl 4-oxopimelate (40percent yield with respect to iron), whether in an atmosphere of CO or argon.These reactions are shown to proceed by regioselective addition of KHFe(CO)4, to ethyl acrylate to give an intermediate alkyl tetracarbonylferrate 2 (M=K), which has been isolated as the PPN+ salt.In situ protonation of 2 (or of the isomeric alkyltetracarbonylferrate 10) by the solvent, and reductive elimination of ethyl propionate generate a coordinatively unsaturated Fe(CO)4 species which, when quenched in situ, gives the corresponding Fe(CO4)(acrylate) complex 9.In the presence of K2CO3 and an excess of ethyl acrylate, 9 affords ethyl propionate in 120percent yield with respect to iron, which is consistent with observed pseudo-catalytic reduction of ethyl acrylate by KHFe(CO)4.The formation of diethyl oxopimelate is thought to involve the isomerisation of 2, followed by reaction of the resulting alkyltetracarbonylferrate 10 with ethyl acrylate.
- Brunet, Jean-Jacques,Passelaigue, Elisabeth
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p. 203 - 216
(2007/10/02)
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- SYNTHESIS OF 4-KETO PIMELATES BY PALLADIUM-CATALYZED CARBONYLATIVE SYMMETRICAL COUPLING OF SILOXYCYCLOPROPANES
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Treatment of 1-alkoxy-1-siloxycyclopropane with a catalytic amount of a palladium/phosphine complex in chloroform under carbon monoxide atmosphere gives 4-keto pimelate.
- Aoki, Satoshi,Nakamura, Eiichi,Kuwajima, Isao
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p. 1541 - 1542
(2007/10/02)
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- SYNTHESIS OF γ-KETOPIMELIC ACID DERIVATIVES BY RHODIUM CARBONYL-CATALYZED HYDROCARBONYLATION OF ACRYLIC ACID DERIVATIVES
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The rhodium carbonyl-catalyzed reactions of acrylic acid derivatives (1) with CO in iso-propanol gave selectively γ-ketopimelic acid derivatives (2) in good yields.In the reaction of ethyl acrylate (1b) in iso-propanol-d8, deuterium scrambling in the methylene groups of the products (2b) was observed.
- Hong, Pangbu,Mise, Takaya,Yamazaki, Hiroshi
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p. 361 - 364
(2007/10/02)
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