- Highly efficient synthesis of chiral aromatic ketones: Via Rh-catalyzed asymmetric hydrogenation of β,β-disubstituted enones
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A succinct and efficient protocol was developed for the synthesis of chiral aromatic ketones via asymmetric hydrogenation of β,β-disubstituted enones with rhodium catalysts based on chiral bisphosphine thiourea ligands. A series of substrates (17 examples) was smoothly catalyzed to afford the corresponding chiral aromatic ketones in high conversions (>99%) with excellent enantioselectivities (up to 96% ee).
- Zhang, Tao,Jiang, Jun,Yao, Lin,Geng, Huiling,Zhang, Xumu
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supporting information
p. 9258 - 9261
(2017/08/22)
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- Addition reaction of arylboronic acids to aldehydes and α,β-unsaturated carbonyl compounds catalyzed by conventional palladium complexes in the presence of chloroform
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Arylboronic acids react with aldehydes and α,β-unsaturated carbonyl compounds in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding addition products in good yields, and chiral benzhydrol was obtained with up to 43% e.e. using (S,S)-bppm as a ligand. General palladium complexes have no catalytic activity without chloroform. Because chloroform is essential for this reaction, these reactions would be promoted by dichloromethylpalladium(II) species.
- Yamamoto, Tetsuya,Iizuka, Michiko,Takenaka, Hiroto,Ohta, Tetsuo,Ito, Yoshihiko
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experimental part
p. 1325 - 1332
(2009/09/28)
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- Direct competitive enzyme-linked immunosorbent assay for the determination of the highly polar short-chain sulfophenyl carboxylates
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A direct enzyme-linked immunosorbent assay for the detection of the short-chain sulfophenylcarboxylic acids (SPCs), the main metabolites of the linear alkylbenzene-sulfonates, is reported. Six SPCs (2C3, 2C 4, 3C4, 2C
- Estevez, M.-Carmen,Galve, Roger,Sanchez-Baeza, Francisco,Marco, M.-Pilar
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p. 5283 - 5293
(2008/02/02)
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- (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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- Stereoselective synthesis of tetrasubstituted (Z)-alkenes from aryl alkyl ketones utilizing the Horner-Wadsworth-Emmons reaction
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Tetrasubstituted (Z)-alkenes were readily prepared through the Horner-Wadsworth-Emmons reactions of methyl 2-[bis(2,2,2-trifluoroethyl) phosphono]propionate with aryl alkyl ketones by employing Sn(OSO 2CF3)2 and N-ethylpiperidine.
- Sano, Shigeki,Takehisa, Tomoka,Ogawa, Shiho,Yokoyama, Kenji,Nagao, Yoshimitsu
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p. 1300 - 1302
(2007/10/03)
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- New reaction mode of the Horner-Wadsworth-Emmons reaction using Sn(OSO2CF3)2 and N-ethylpiperidine
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Excellent Z or E selectivity is observed in the Horner-Wadsworth-Emmons reactions of methyl bis(trifluoroethyl)phosphonoacetate 2 with aryl alkyl ketones 3a-d or aldehydes 3f,g using Sn(OSO2CF3)2 in the presence of N-ethylpiperidine, which should have a different reaction mode to those using sodium hydride.
- Sano, Shigeki,Yokoyama, Kenji,Fukushima, Mari,Yagi, Tetsuo,Nagao, Yoshimitsu
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p. 559 - 560
(2007/10/03)
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- Stereoselective coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of CuI
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Stereoselective synthesis of trisubstituted alkenes linked with ester groups via coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of Equal molar quantities of CuI was reported.
- Huang, Xian,Zhao, Chang-Qiu
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p. 3491 - 3495
(2007/10/03)
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- Stereoselective synthesis of 3-alkylcinnamic esters via coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters in presence of CuI
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Coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters with Grignard reagents in presence of CuI produced trisubstituted alkenes containing ester groups with retention of configuration.
- Huang, Xian,Zhao, Chang-Qiu
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p. 237 - 241
(2007/10/03)
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- Electron Transfer Profile of Cyclopropanone Acetals in the Nonirradiated Reaction with Tetracyanoethylene, Chloranil, and Dicyanodichlorobenzoquinone
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The donor profiles of cyclopropanone acetals 1 and 2 were examined in the reactions with electron acceptors (TCNE, DDQ, chloranil, and 1-cyanonaphthalene).With TCNE under nonirradiating conditions, an exclusive 2 + 2 cycloaddition took place stereospecifically with monosubstituted acetals 1a-c but nonstereospecifically with disubstituted acetals 1d,e.With quinones, a ring-opening of the cyclopropane and its coupling with the quinone took place to give the C (cyclopropane)-O (quinone) adduct 9 (with chloranil) or 10 (with DDQ), the latter of which underwent the elimination of a phenol to produce unsaturated esters 5 and 6.In addition, the intervention of the C (cyclopropane)-C (quinone) adduct 14 (with chloranil) or 15 (with DDQ), both as the precursor of 5 and 6, was also postulated.With 1-cyanonaphthalene, under photolysis, the cis/trans isomerization of 1 and 2 occured.The results provided evidences that cyclopropanone acetals, in general, are prone to function as donors.The mechanism of the reaction with quinones, in particular, was investigated in detail.
- Oku, Akira,Abe, Manabu,Iwamoto, Masaharu
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p. 7445 - 7452
(2007/10/02)
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- Formation of Unsaturated Esters in the Single Electron Transfer Reaction of Cyclopropanone Acetals with Quinones under Non-irradiated Conditions
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Unsaturated esters were formed from cyclopropanone aceytals in the reaction with DDQ or chloranil, where ring-opened C-C and C-O bonded adducts were the intermediates formed via a SET mechanism resulting in the ester formation.
- Abe, Manabu,Oku, Akira
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p. 3551 - 3554
(2007/10/02)
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- Polarized Ketene Dithioacetals. 28. A New General Highly Stereoselective and Regiospecific Method for Homologation of Ketones to α,β-Unsaturated Esters via α-Oxoketene Dithioacetals
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A new highly stereoselective and regiospecific general method for the conversion of active methylene ketones to α,β-unsaturated O-methyl esters, S-methyl esters, and aldehydes via the corresponding oxoketene dithioacetals has been developed.Thus the carbinols 7a-g obtained by sodium borohydride reduction of the corresponding oxoketene dithioacetals 6a-g, derived from acetophenones and their higher homologues, have been shown to undergo boron trifluoride etherate assisted methanolysis to give the corresponding (E)-methylcinnamates 3a-d and their α-alkyl derivatives 3e-g in high yields.Also the acetals 6h-k derived from alkylmethyl ketones gave the corresponding (E)-methylcrotonates 3h-k.Similarly, the acetals 6l-p derived from alicyclic ketones gave the corresponding cyclic ene esters 3l-p under identical conditions.A few carbinols, 7a-d, were shown to undergo partial hydrolysis in the presence of boron trifluoride etherate/water to give the corresponding S-methyl thiocinnamates 8a-d.The cyclic acetals 6l-n were also similarly converted to the corresponding cyclic S-methylene thio esters 8e-g.The (methylthio)alkenyl ketones 20a-d and 18 after borohydride reduction and acidic hydrolysis gave the corresponding (E)-α,β-unsaturated aldehydes 22a-d and 19.The mechanism governing these transformations has been proposed.
- Myrboh, Bekington,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
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p. 5327 - 5332
(2007/10/02)
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