- Synthesis of new chiral keto alcohols by baker's yeast
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Fourteen chiral α- and β-keto alcohols 2a-2r were synthesized by the asymmetric reduction of their corresponding diketones 1a-1r via baker's yeast. In addition, ten corresponding racemic α-keto alcohols were synthesized by the benzoin condensation of their corresponding aldehydes, which were used for the determination of the ee values through their chiral resolution on chiral HPLC. Amongst the 15 diketones, 1j and chiral α-keto alcohols 2i, 2j and chiral β-keto alcohol 2r are novel compounds. Six keto alcohols 2b, 2c, 2d, 2f, 2h and 2p were synthesized by baker's yeast for the first time. There are some studies in the literature where baker's yeast was applied to the diketones 1a, 1g, 1e, 1k and 1n under various conditions different to those reported herein. The yields and the ee values of these studies were not as high as ours. All of the keto alcohols synthesized were characterized by IR, NMR (1H and 13C), and MS. The relationship between the structure of the diketone and the yield, diastereoselectivity and enantiomeric excess is also discussed.
- Yildiz, Tuelay,Canta, Nurguel,Yusufoglu, Ayse
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p. 340 - 347
(2014/04/03)
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- Synthesis of chiral 2-aroyl-1-tetralols: Asymmetric transfer hydrgenation of 2-aroyl-1-tetralones via dynamic kinetic resolution
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The dynamic kinetic resolution of 2-aroyl-1-tetralones was achieved via asymmetric transfer hydrogenation using (S,S)-RuCl(p-cymene)TsDPEN (TsDPEN=N-(tosyl)-1,2-diphenylethylenediamine) in formic acid/triethyl- amine (5:2, molar ratio), afforded the desired products in good yields (up to 85%) with diastereomeric ratio up to >99:1 and high enantiomeric excesses (up to >99%). The absolute configuration of major the product was confirmed by X-ray crystal structure analysis. Copyright
- Wu, Yun,Geng, Zhicong,Bai, Jinjin,Zhang, Yawen
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experimental part
p. 1467 - 1472
(2011/11/05)
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- Titanocene-promoted intermolecular couplings of epoxides with nitriles. An easy access to β-hydroxyketones
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(Chemical Equation Presented) Radical couplings of epoxides and nitriles mediated by Cp2TiCl provide a diastereoselective route to the synthesis of β-hydroxyketones. The conditions of this "aldol- like" reaction are mild enough to avoid the dehydration of the β-hydroxyketone. The scope of the coupling reaction with functionalized and tetrasubstituted epoxides has been studied. The radical character of the coupling reactions is demonstrated.
- Fernandez-Mateos,Encinas Madrazo,Herrero Teijon,Rubio Gonzalez
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supporting information; experimental part
p. 3913 - 3918
(2009/10/20)
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- TBD-catalyzed direct 5- and 6-enolexo aldolization of ketoaldehydes
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Treatment of unfunctionalized acyclic ketoaldehydes with a catalytic amount of 1,5,7-triazabicyclo[4.4.0]dec-5-ene induces a direct intramolecular 5- and 6-enolexo aldolization, furnishing 2-ketocyclopentanols and 2-ketocyclohexanols in good-to-excellent yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Ghobril, Cynthia,Sabot, Cyrille,Mioskowski, Charles,Baati, Rachid
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supporting information; experimental part
p. 4104 - 4108
(2009/05/27)
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- Indium(III) acetate-catalyzed 1,4-reduction and reductive aldol reactions of α-enones with phenylsilane
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A catalytic amount of In(OAc)3 smoothly promoted 1,4-reduction of certain α-enones with PhSiH3 in ethanol at ambient temperature. The intermediary enolates could be used for inter- and intramolecular aldol reactions and intramolecular Michael addition.
- Miura, Katsukiyo,Yamada, Yusuke,Tomita, Mitsuru,Hosomi, Akira
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p. 1985 - 1989
(2007/10/03)
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- Selective 1,4-reduction of unsaturated carbonyl compounds using Co2(CO)8-H2O
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α,β-Unsaturated ketones and aldehydes were selectively reduced to the corresponding saturated carbonyl compounds by Co2(CO)8-H2O system. The current reducing system also offered a chemoselective reduction of less substituted unsaturated carbonyl groups.
- Lee, Hee-Yoon,An, Mihyun
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p. 2775 - 2778
(2007/10/03)
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- Reductive generation of enolates from enones using elemental hydrogen: Catalytic C-C bond formation under hydrogenative conditions
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Exposure of enones to elemental hydrogen in the presence of a Rh(I) catalyst enables reductive enolate generation, as evidenced by electrophilic trapping of the enolate by appendant and exogenous aldehyde partners. The significance of these findings resides in the ability to regioselectivity generate and transform transition metal enolates under catalytic conditions that circumvent formation of stoichiometric byproducts. Copyright
- Jang, Hye-Young,Huddleston, Ryan R.,Krische, Michael J.
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p. 15156 - 15157
(2007/10/03)
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- Diastereoselective cycloreductions and cycloadditions catalyzed by Co(dpm)2-silane (dpm = 2,2,6,6-tetramethylheptane-3,5-dionate): Mechanism and partitioning of hydrometallative versus anion radical pathways
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In the presence of phenylsilane and 5 mol % cobalt(II) bis(2,2,6,6-tetramethylheptane-3,5-dionate), aryl-substituted monoenone monoaldehydes and bis(enones) undergo reductive cyclization to afford synaldol and anti-Michael products, respectively. For both
- Wang, Long-Cheng,Jang, Hye-Young,Roh, Yeonsuk,Lynch, Vincent,Schultz, Arthur J.,Wang, Xiaoping,Krische, Michael J.
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p. 9448 - 9453
(2007/10/03)
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- Synthesis of carbocycles by enone-selective reduction using organoiodotin hydride
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By using di-n-butyliodotin hydride (n-Bu2SnIH), carbocycles were prepared from substrates bearing both enone and formyl moieties, where the enone-selective reduction was followed by a diastereoselective intramolecular aldol reaction. (C) 2000 Elsevier Science Ltd.
- Suwa, Toshihiro,Nishino, Keita,Miyatake, Masato,Shibata, Ikuya,Baba, Akio
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p. 3403 - 3406
(2007/10/03)
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- Stereoselective Ring Opening Reaction of 2-cycloalkanols Mediated by N-Chlorosuccinimide and Triethylamine
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Treatment of 2-cyclohexanol (2c) with N-chlorosuccinimide (NCS) and triethylamine gave various product 3-6c depending on reaction conditions.Exclusive ring-opening reaction of 2c was achieved by temperature control.Thus, five-, six-, and seven-membered cycloalkanols 2a-g were converted to ω-oxo-α,β-unsaturated sulfides 6a-g in good yields.The stereochemistry of the reaction was determined by using four diastereomers 10a-d; trans-erythro-10b and cis-threo-10c afforded (E)- and (Z)-heptenals 6c as a single isomer, respectively, while a mixture of the two isomers 6c (60:40 or 40:60) was obtained from trans-threo-10a and cis-erythro-10d.Allyl-, propargyl-, and cyclohexanols 23, 25, and 27 also yielded corresponding unsaturated sulfides 24, 26, and 28.
- Takaki, Ken,Yasumura, Masateru,Tamura, Takao,Negoro, Kenji
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p. 1256 - 1261
(2007/10/02)
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- The Reaction of Sodium 1,3-Diphenyl-2-azapropenide with 1,2-Epoxycyclohexane
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Ring opening of 1,2-epoxycyclohexane by the title aza-allylic anion afforded a mixture of anions, the quenching and subsequent hydrolysis of which gave rise to trans-2-(α-aminobenzyl)cyclohexanol (10) and benzylamine as the basic fraction, and to either 1-benzoylcyclohexene (11) or trans-2-benzoylcyclohexanol (12), cis-2-benzoylcyclohexanol (14), and benzaldehyde as the neutral fraction: the type of ketone obtained depended upon the hydrolytic conditions.The perhydrobenzoxazine (7) was shown to be the precursor of compound (10).Sodium 1,3-diphenyl-2-azapropenide thus behaved both as an α-benzylamine carbanion equivalent and as a benzoyl anion equivalent.
- Bradamante, Silvia,Ferraccioli, Raffaella,Pagani, Giorgio A.
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p. 515 - 518
(2007/10/02)
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