- Selective catalytic synthesis of α-alkylated ketones and β-disubstituted ketones via acceptorless dehydrogenative cross-coupling of alcohols
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Herein, a phosphine-free pincer ruthenium(III) catalyzed β-alkylation of secondary alcohols with primary alcohols to α-alkylated ketones and two different secondary alcohols to β-branched ketones are reported. Notably, this transformation is environmentally benign and atom efficient with H2O and H2 gas as the only byproducts. The protocol is extended to gram-scale reaction and for functionalization of complex vitamin E and cholesterol derivatives.
- Bhattacharyya, Dipanjan,Sarmah, Bikash Kumar,Nandi, Sekhar,Srivastava, Hemant Kumar,Das, Animesh
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supporting information
p. 869 - 875
(2021/02/06)
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- Asymmetric transfer hydrogenation of unsaturated ketones; factors influencing 1,4- vs 1,2- regio- and enantioselectivity, and alkene vs alkyne directing effects
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A detailed study has been completed on the asymmetric transfer hydrogenation (ATH) of a series of enones using Ru(II) catalysts. Electron-rich rings adjacent to the C[dbnd]O group reduce the level of C[dbnd]O reduction compared to C[dbnd]C. The ATH reaction can readily discriminate between double and triple bonds adjacent to ketones, reducing the double bond but leaving a triple bond intact in the major product.
- Hall, Thomas H.,Adams, Hannah,Vyas, Vijyesh K.,Michael Chu,Wills, Martin
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- Acylation of Alkenes with the Aid of AlCl3 and 2,6-Dibromopyridine
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Friedel-Crafts-type acylation of alkenes with acyl chlorides has been successfully conducted with a wide substrate scope by the combined use of AlCl3 and 2,6-dibromopyridine. Trisubstituted alkenes afford allylketones or vinylketones depending on the presence or absence of hydrogen atom(s) at the β-position to the acylation site, while monosubstituted alkenes exclusively afford vinylketones.
- Tanaka, Shinya,Kunisawa, Tsukasa,Yoshii, Yuji,Hattori, Tetsutaro
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supporting information
p. 8509 - 8513
(2019/11/03)
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- Triazole-gold-promoted, effective synthesis of enones from propargylic esters and alcohols: A catalyst offering chemoselectivity, acidity and ligand economy
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The air, moisture and thermally stable 1,2,3-triazole coordinated gold(I) complexes (TA-Au) were revealed as the effective catalysts in promoting propargylic ester rearrangement and sequential allene hydration, giving the enones with excellent yields (up to 97% yields, 0.2% loading). The catalysts could also catalyze the more challenging Meyer-Schuster rearrangement (0.5% loading, up to 98% yields). The reported reaction confirmed TA-Au as a chemoselective catalyst in promoting alkyne activation with high efficiency and improved ligand economy. Copyright
- Wang, Dawei,Zhang, Yanwei,Harris, Alexandria,Gautam, Lekh Nath S.,Chen, Yunfeng,Shi, Xiaodong
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supporting information; experimental part
p. 2584 - 2588
(2011/12/01)
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- Gold-catalyzed highly regioselective oxidation of C-C triple bonds without acid additives: Propargyl moieties as masked α,β-unsaturated carbonyls
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Gold-catalyzed intermolecular oxidations of internal alkynes have been achieved with high regioselectivities using 8-alkylquinoline N-oxides as oxidants and in the absence of acid additives. Synthetically versatile α,β-unsaturated carbonyls are obtained in good to excellent yields and with excellent E-selectivities. A range of functional groups such as THP, MOMO, N3, OTBS, and N-Boc are tolerated. This reaction allows α,β-unsaturated carbonyls to be masked as propargyl moieties, thus offering a practical solution to compatibility issues with these functional groups likely encountered in syntheses of complex structures.
- Lu, Biao,Li, Chaoqun,Zhang, Liming
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supporting information; experimental part
p. 14070 - 14072
(2011/01/04)
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- Gold-catalyzed efficient formation of α,β-unsaturated ketones from propargylic acetates
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An efficient gold-catalyzed method for the preparation of α,β-unsaturated ketones from propargylic acetates has been developed. Under mild reaction conditions, β-monosubstituted enones were formed mostly with excellent E-selectivity. β,β-Disubstituted enones can be prepared from propargylic acetates derived from ketones. The high efficiency and mild nature of this reaction render it a viable alternative for the synthesis of α,β-unsaturated ketones.
- Yu, Meng,Li, Guotao,Wang, Shaozhong,Zhang, Liming
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p. 871 - 875
(2008/03/27)
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- Multicomponent synthesis of dihydropyrimidines and thiazines
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A broad range of differently substituted dihydropyrimidines and thiazines can be efficiently prepared by using a four-component reaction between phosphonates, nitriles, aldehydes, and iso(thio)cyanates. The scope and limitations of this multicomponent reaction are fully described. Variation of all four components has been investigated. The nitrile and aldehyde inputs can be varied extensively, but variation of the phosphonate input remains limited. An interesting rearrangement leading to phosphoramidates has been observed, Furthermore, the multicomponent reaction seems to be restricted to the use of isocyanates with strongly electron-withdrawing substituents, but an interesting additional exchange reaction under microwave conditions leads to dihydropyrimidines with less electron-withdrawing substituents at N3. In addition, a diastereoselective formation of dihydropyrimidines has been observed when using a chiral aldehyde as the input. Finally, by changing the isocyanate component to an isothiocyanate, thiazines are efficiently formed instead of the corresponding thio-dihydropyrimidines.
- Vugts, Danielle J.,Koningstein, Manoe M.,Schmitz, Rob F.,De Kanter, Frans J. J.,Groen, Marinus B.,Orru, Romano V. A.
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p. 7178 - 7189
(2007/10/03)
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- Oxidative Generation of 1-Nitroalkyl Radicals and Their Addition Reaction to Olefins
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1-Nitroalkyl radicals are generated by oxidation of potassium salt of 1-aci-nitroalkanes with ammonium hexanitratocerate(IV). When the oxidation is carried out in the presence of electron-rich olefins, such as silyl enol ethers, intermolecular addition of the radicals onto the olefins proceeds to afford β-nitro ketones, which are further converted to α,β-unsaturated ketones in high yield. Stereoselective construction of fused ring systems is achieved by intramolecular addition of 1-nitroalkyl radicals.
- Arai, Noriyoshi,Narasaka, Koichi
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p. 2525 - 2534
(2007/10/03)
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- Generation of α-Nitroalkyl Radicals by Oxidation of Nitronate Anions with Cerium(IV) Ammonium Nitrate and Their Addition Reaction to Electron-Rich Olefins
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α-Nitroalkyl radicals are generated by oxidation of nitronate anions with cerium(IV) ammonium nitrate.When the reactions are carried out in hte presence of electron-rich olefins, such as silyl enol ethers, intermolecular addition of the radicals proceeds to afford β-nitroketones, which are further converted to α,β-unsaturated ketones in good yield.
- Arai, Noriyoshi,Narasaka, Koichi
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p. 987 - 988
(2007/10/03)
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- On tertiary stibine I. Reaction of ω-bromoacetophenone with aldehydes mediated by diphenylantimonyorganometallic reagents
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In the presence of diphenylantimonymagnesium, various aldehydes react readily with ω-bromoacetophenone to form α,β-unsaturated ketones in good yields.
- Zhang, Li-Jun,Huang, Yao-Zeng
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p. 101 - 103
(2007/10/02)
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- One-pot synthesis of α,β-unsaturated ketones
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The preparation of α,β-unsaturated ketones is performed in a one-pot procedure by subsequent treatment of diethyl lithiomethylphosphonate with nitriles, followed by addition of carbonyl compounds and hydrolysis.
- Lee,Oh
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p. 213 - 214
(2007/10/02)
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- Benzotriazole-assisted synthesis of novel mannich bases from ketones and diverse aldehydes
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A wide variety of β-amino ketones are prepared in moderate to good yields by the reaction of the lithium enolates of cyclohexanone, acetophenone, α-tetralone and camphor with the readily available adducts from an aldehyde or ketone, an amine and benzotriazole. Some diastereoselectivity is observed when the benzotriazole adduct is derived from benzaldehyde.
- Katritzky, Alan R.,Harris, Philip A.
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p. 987 - 996
(2007/10/02)
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- 1,4-DIANION OF ACETOPHENONE N-ETHOXYCARBONYLHYDRAZONE AS A SYNTHETIC INTERMEDIATE
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Various β-hydroxyketones and α,β-unsaturated ketones were prepared by the reaction of aldehydes and ketones with 1,4-dianion (2) which is derived from acetophenone N-ethoxycarbonylhydrazone (1) with butyllithium.In the reaction of 2 with carbonyl compounds such as ester, amide, acid anhydride, acyl chloride, and alkyl carbonate, pyrazole derivatives were obtained in good yields.
- Matsumura, Noboru,Kunugihara, Akira,Yoneda, Shigeo
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p. 3239 - 3242
(2007/10/02)
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