- Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
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An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
- Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Zhang, Dong,Zhang, Fengcai
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supporting information
p. 6961 - 6966
(2021/09/11)
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- Light-Driven Carbene Catalysis for the Synthesis of Aliphatic and α-Amino Ketones
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Single-electron N-heterocyclic carbene (NHC) catalysis has gained attention recently for the synthesis of C?C bonds. Guided by density functional theory and mechanistic analyses, we report the light-driven synthesis of aliphatic and α-amino ketones using single-electron NHC operators. Computational and experimental results reveal that the reactivity of the key radical intermediate is substrate-dependent and can be modulated through steric and electronic parameters of the NHC. Catalyst potential is harnessed in the visible-light driven generation of an acyl azolium radical species that undergoes selective coupling with various radical partners to afford diverse ketone products. This methodology is showcased in the direct late-stage functionalization of amino acids and pharmaceutical compounds, highlighting the utility of single-electron NHC operators.
- Bay, Anna V.,Cheong, Paul Ha-Yeon,Farah, Abdikani Omar,Fitzpatrick, Keegan P.,González-Montiel, Gisela A.,Scheidt, Karl A.
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supporting information
p. 17925 - 17931
(2021/07/17)
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- Synthesis of unsymmetrical ketones by applying visible-light benzophenone/nickel dual catalysis for direct benzylic acylation
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Herein, we report a dual catalytic system for the direct benzylic C-H acylation reaction furnishing a variety of unsymmetrical ketones. A benzophenone-derived photosensitizer combined with a nickel catalyst has been established as the catalytic system. Both acid chlorides and anhydrides are able to acylate the benzylic position of toluene and other methylbenzenes. The method offers a valuable alternative to late transition metal catalyzed C-H acylation reactions.
- Krach, Patricia E.,Dewanji, Abhishek,Yuan, Tingting,Rueping, Magnus
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supporting information
p. 6082 - 6085
(2020/06/18)
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- Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids
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As a key element in the construction of complex organic scaffolds, the formation of C?C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single-electron chemistry have enabled new methods for the formation of various C?C bonds. Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N-heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late-stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies.
- Betori, Rick C.,Davies, Anna V.,Fitzpatrick, Keegan P.,Scheidt, Karl A.
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supporting information
p. 9143 - 9148
(2020/03/30)
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- Balancing Bulkiness in Gold(I) Phosphino-triazole Catalysis
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The syntheses of a series of 1-phenyl-5-phosphino 1,2,3-triazoles are disclosed, within which, the phosphorus atom (at the 5-position of a triazole) is appended by one, two or three triazole motifs, and the valency of the phosphorus(III) atom is completed by two, one or zero ancillary (phenyl or cyclohexyl) groups respectively. This series of phosphines was compared with tricyclohexylphosphine and triphenylphosphine to study the effect of increasing the number of triazoles appended to the central phosphorus atom from zero to three triazoles. Gold(I) chloride complexes of the synthesised ligands were prepared and analysed by techniques including single-crystal X-ray diffraction structure determination. Gold(I) complexes were also prepared from 1-(2,6-dimethoxy)-phenyl-5-dicyclohexyl-phosphino 1,2,3-triazole and 1-(2,6-dimethoxy)-phenyl-5-diphenyl-phosphino 1,2,3-triazole ligands. The crystal structures thus obtained were examined using the SambVca (2.0) web tool and percentage buried volumes determined. The effectiveness of these gold(I) chloride complexes to serve as precatalysts for alkyne hydration were assessed. Furthermore, the regioselectivity of hydration of but-1-yne-1,4-diyldibenzene was probed.
- Zhao, Yiming,Wakeling, Matthew G.,Meloni, Fernanda,Sum, Tze Jing,van Nguyen, Huy,Buckley, Benjamin R.,Davies, Paul W.,Fossey, John S.
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p. 5540 - 5548
(2019/08/07)
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- C?C Bond Formation of Benzyl Alcohols and Alkynes Using a Catalytic Amount of KOtBu: Unusual Regioselectivity through a Radical Mechanism
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We report a C?C bond-forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α-alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways.
- Kumar, Amit,Janes, Trevor,Chakraborty, Subrata,Daw, Prosenjit,von Wolff, Niklas,Carmieli, Raanan,Diskin-Posner, Yael,Milstein, David
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supporting information
p. 3373 - 3377
(2019/02/14)
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- Synthesizing method of alpha-arone or alpha-hetero-arone
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The invention discloses a synthesizing method of alpha-arone or alpha-hetero-arone and belongs to the technical field of metal organic catalyzing. The synthesizing method has the advantages that a terminal alkynyl compound, oxynitride and a proton supply agent is catalyzed by univalence metal salt to obtain N-O pyridine oxynitride enol salt, purification and separation are not needed, and the N-Opyridine oxynitride enol salt is allowed to have reaction with arene and hetero-arene in a one-pot manner to obtain the alpha-arone or alpha-hetero-arone; the method is high in functional group tolerance, wide in substrate application range, high in yield, simple and easy to operate and easy in final product separation and purification.
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- Regioselective Arene and Heteroarene Functionalization: N-Alkenoxypyridinium Salts as Electrophilic Alkylating Agents for the Synthesis of α-Aryl/α-Heteroaryl Ketones
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A direct regioselective functionalization of arenes and heteroarenes using N-alkenoxypyridinium salts as electrophilic alkylating agents for the synthesis of α-aryl/heteroaryl ketones has been developed. The method generates alkylating agents from alkynes and N-pyridine oxide followed by site-selective electrophilic substitution with a broad range of arenes and heteroarenes including benzene derivates, phenols, ethers, indoles, pyrroles, furans, and thiophenes in one pot. Kinetic isotope effect measurements and DFT studies reveal that this reaction likely proceeds through a carbon-cation intermediate.
- Zhai, Rong L.,Xue, Yun S.,Liang, Ting,Mi, Jia J.,Xu, Zhou
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p. 10051 - 10059
(2018/07/30)
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- Radical-Based C?C Bond-Forming Processes Enabled by the Photoexcitation of 4-Alkyl-1,4-dihydropyridines
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We report herein that 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) can directly reach an electronically excited state upon light absorption and trigger the generation of C(sp3)-centered radicals without the need for an external photocatalyst. Selective excitation with a violet-light-emitting diode turns alkyl-DHPs into strong reducing agents that can activate reagents through single-electron transfer manifolds while undergoing homolytic cleavage to generate radicals. We used this photochemical dual-reactivity profile to trigger radical-based carbon–carbon bond-forming processes, including nickel-catalyzed cross-coupling reactions.
- Buzzetti, Luca,Prieto, Alexis,Roy, Sudipta Raha,Melchiorre, Paolo
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supporting information
p. 15039 - 15043
(2017/11/20)
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- Ni-catalyzed reductive coupling of alkyl acids with unactivated tertiary alkyl and glycosyl halides
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This work highlights Ni-catalyzed reductive coupling of alkyl acids with alkyl halides, particularly sterically hindered unactivated tertiary alkyl bromides for the production of all carbon quaternary ketones. The reductive strategy is applicable to α-selective synthesis of saturated, fully oxygenated C-acyl glycosides through easy manipulations of the readily available sugar bromides and alkyl acids, avoiding otherwise difficult multistep conversions. Initial mechanistic studies suggest that a radical chain mechanism (cycle B, Scheme 1) may be plausible, wherein MgCl2 promotes the reduction of NiII complexes.
- Zhao, Chenglong,Jia, Xiao,Wang, Xuan,Gong, Hegui
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supporting information
p. 17645 - 17651
(2015/02/05)
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- Triphenylphosphine-cyclometallated iridium(III) pyrimidine complexes: Synthesis, crystal structures and application in α-alkylation of ketones with alcohols
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Two triphenylphosphine (PPh3)-cyclometallated iridium(III) pyrimidine complexes Ir(NDMP)2PPh3Cl 1 and Ir(NDMP)(PPh3)2Cl2 2 (NDMP = 2-(2-naphthyl)-4,6- dimethyl-pyrimidine) were synthesized and characterized by NMR, IR, ESI-MS, and elemental analysis. Additionally, their detailed structures have been determined by X-ray single-crystal diffraction. The complex 1 was a PPh3-biscyclometalated Ir(III) complex, while 2 was a PPh 3-monocyclometalated Ir(III) complex. These complexes were found to be efficient catalysts for α-alkylation of ketones with alcohols.
- Xu, Chen,Dong, Xin-Ming,Wang, Zhi-Qiang,Hao, Xin-Qi,Li, Zhen,Duan, Lu-Meng,Ji, Bao-Ming,Song, Mao-Ping
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experimental part
p. 214 - 218
(2012/03/11)
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- C-X (X=Br, I) bond-tolerant aerobic oxidative cross-coupling: A strategy to selectively construct β-aryl ketones and aldehydes
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Using moelcular oxygen as the terminal oxidant, various aryl halide-containing β-aryl ketones and aldehydes can be synthesized directly from readily available allyic alcohols and boronic acids via palladium-catalyzed oxidative cross-coupling reactions. The dual roles of copper, including electron-carrier and Lewis acid functions, are supposed to be critical for the high reactivity and selectivity of this aerobic oxidative coupling transformation. Copyright
- Chen, Mao,Wang, Jie,Chai, Ziyi,You, Cai,Lei, Aiwen
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supporting information; experimental part
p. 341 - 346
(2012/05/04)
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- Aryl(chloro)methyl 4-tolyl sulfoxides: Synthesis and application to the synthesis of α-aryl ketones
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Aryl(chloro)methyl 4-tolyl sulfoxides were synthesized from arylmethyl 4-tolyl sulfoxides in moderate-to-good yields by sequential treatment with lithium diisopropylamide and tosyl chloride at low temperatures. Treatment of the lithium α-sulfinyl carbanion of the aryl(chloro)methyl 4-tolyl sulfoxides with aldehydes or ketones resulted in the formation of adducts in good-to-high yields. Treatment of these adducts with tert-butylmagnesium chloride gave the corresponding magnesium alkoxides. On treatment with isopropylmagnesium chloride, the alkoxides gave the corresponding magnesium β-oxido carbenoids, which rearranged to give α-aryl ketones in good-to-high yields. The magnesium enolate intermediates generated by rearrangement of the -oxido carbenoids could also be trapped with electrophiles to give α-aryl α-substituted ketones. These procedures offer a good method for the synthesis of a variety of α-aryl ketones from aldehydes and ketones. Georg Thieme Verlag Stuttgart. New York.
- Fukuda, Shigehiko,Tsuji, Kazuhito,Musashi, Jun,Nonaka, Ryo,Kimura, Tsutomu,Satoh, Tsuyoshi
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p. 3615 - 3626
(2011/12/16)
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- Rapid and regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester catalyzed by titanium tetrachloride
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A regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester as the reducing agent and titanium tetrachloride as a catalyst is described. The short reaction times and mild reaction conditions are the advantages of this method. Georg Thieme Verlag Stuttgart New York.
- Che, Jun,Lam, Yulin
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experimental part
p. 2415 - 2420
(2010/11/19)
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- Empirical method for predicting enantioselectivity in catalytic reactions: demonstration with lipase and oxazaborolidine
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We derived a novel equation capable of predicting the degree of enantioselectivity in a catalytic reaction without any knowledge of the reaction mechanism and/or the transition-state structure, and tested the validity of this equation by changing substrates systematically in the lipase or oxazaborolidine-catalyzed reactions. A good correlation was observed between the predicted and observed E values, and the stereochemistry of the products could be predicted correctly in most cases (28 out of 30).
- Ema, Tadashi,Ura, Norichika,Yoshii, Masataka,Korenaga, Toshinobu,Sakai, Takashi
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experimental part
p. 9583 - 9591
(2010/01/06)
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- Fluorotetraphenylbismuth: A new reagent for efficient regioselective α-phenylation of carbonyl compounds
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Synthesis and X-ray crystallographic characterization of fluorotetraphenylbismuth (1) has been achieved for the first time, revealing that the bismuth center of 1 adopts a distorted trigonal bipyramidal geometry with three ipso carbons at the equatorial sites and one ipso carbon and fluorine atom at the apical sites. Contrary to the previous common understanding of this type of organobismuth(V) compound, 1 was found to be thermally stable, maintaining its amphiphilic property. Hence, 1 can be used as an off-the-shelf reagent in organic synthesis, and its utility has been clearly demonstrated in applications to the efficient α-phenylation of ketones and esters. For instance, simple mixing of 1 and 1-trimethylsiloxy-3,4-dihydronaphthalene in THF at -40 °C and stirring at room temperature for 10 min gave rise to 2-phenyl-1-tetralone almost quantitatively without formation of the polyphenylated products. In addition to the generality of this method, applicability of our approach to the selective α-alkenylation of carbonyl compounds was also demonstrated by the use of fluoro(2-phenylethenyl)tris(p-tolyl)bismuth (2) as a representative reagent. These results imply the vast potential of organobismuth(V) compounds of type 1 and 2 as useful precursors of a wide variety of pentavalent organobismuth compounds based on the utilization of the eminent fluorine-silicon interaction or the inherent basicity of the fluorine atom. Copyright
- Ooi, Takashi,Goto, Ryoji,Maruoka, Keiji
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p. 10494 - 10495
(2007/10/03)
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- Copper(II) chloride mediated racemization-free hydrolysis of α- alkylated ketone SAMP-hydrazones
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Treatment of ketone SAMP-hydrazones 1a-k with an aqueous copper(II) chloride solution yields the corresponding ketones 2a-k in 52-94% yield and with high enantiomeric purities (ee = 89-99%). The cleavage conditions do not affect functionalities sensitive to oxidation and strong acids. The alkylation/cleavage protocol can be carried out in 'one-pot'.
- Enders, Dieter,Hundertmark, Thomas,Lazny, Ryszard
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- Synthesis of ketones and aldehydes via reactions of Weinreb-type amides on solid support
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Ketones and aldehydes were formed in low to good yields in reactions of Weinreb-type amides on solid support and no overaddition occurred.
- Dinh, Tam Q.,Armstrong, Robert W.
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p. 1161 - 1164
(2007/10/03)
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- Synthesis of symmetrical ketones from aldehydes catalysed by dioobaltoctacarbonyl
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Under a pressure of synthesis gas, dicobaltoctacarbonyl in pyridine selectively catalyses the coupling reaction of aldehydes to ketones.
- Fontaine,Noels,Demoneeau,Hubert
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p. 3117 - 3120
(2007/10/02)
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- Formation of a Novel Acyl Anion Equivalent by the Electroreduction of Oxazolinium Salts
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Electroreduction of oxazolinium salts synthesized from the corresponding carboxylic acids gave a novel acyl anion equivalent (AAE).The reaction of these AAEs with electrophiles afforded the corresponding aldehydes or ketones in good yields.
- Shono, Tatsuya,Kashimura, Shigenori,Yamaguchi, Yoshihide,Ishige, Osamu,Uyama, Hiroshi,Kuwata, Fumitaka
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p. 1511 - 1512
(2007/10/02)
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- PALLADIUM-CATALYZED CARBONYLATIVE CROSS-COUPLING OF ORGANOBORANES WITH ARYL IODIDES OR BENZYL HALIDES IN THE PRESENCE OF BIS(ACETYLACETONATO)ZINC (II)
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Carbonylative cross-coupling reactions of organoboranes with aryl iodides and benzyl halides successfully catalyzed by dichlorobis(triphenylphosphine)palladium(II) in the presence of bis(acetylacetonato)zinc(II) procedure unsymmetrical ketones in reasonable yields.
- Wakita, Yoshiaki,Yasunaga, Tomoyuki,Akita, Masahiro,Kojima, Masaharu
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p. C17 - C20
(2007/10/02)
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- REGIOSPECIFIC SYNTHESIS OF α-(PHENYLTHIO)CYCLOALKENONES AND OF α-PHENYL-α-(PHENYLTHIO)KETONES VIA αα-ADDITION OF PHENYLSULPHENYL CHLORIDE TO α-DIAZOKETONES
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Cyclic α-diazoketones react with phenylsulphenyl chloride at room temperature to furnish α-chloro-α-(phenylthio)cycloalkanones which undergo ready dehydrochlorination to α-(phenylthio)cycloalkenones when treated with triethylamine; acyclic, terminal α-diazoketones also furnish α-chloro-α-(phenylthio)adducts which are useful electrophiles in the synthesis of α-phenyl-α-(phenylthio)ketones.
- McKervey, M. Anthony,Ratananukul, Piniti
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p. 117 - 120
(2007/10/02)
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- A Convenient Method for the Synthesis of Acyclic Ketones. Synthesis of Sex Pheromone of Douglas Fir Tussock Moth
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(α-Alkyl-α-methylthio)alkyl p-tolyl sulfones derived from the reaction of a-alkylated alkyl p-tolyl sulfones with dimethyl disulfide could be easily hydrolyzed by CuCl2-SiO2 to give the corresponding ketones in fairly good yields.This method was applied to the synthesis of Douglas Fir Tussock Moth Pheromone.
- Murata, Yasue,Inomata, Katsuhiko,Kinoshita, Hideki,Kotake, Hiroshi
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p. 2539 - 2540
(2007/10/02)
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- Transformation of Alkyl Halides to Aldehydes Having Two Additional Carbon Atoms
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Methyl 3-oxo-4-phenylbutanoate (6) reacts with alkyl halides (1a-g) in the presence of NaH/benzene to furnish alkylated β-keto esters (2a-g).Hydrolysis of 2a-g gives benzyl ketones (3a-g), which on reduction with sodium borohydride give the homobenzylic alcohols (4a-g).The alcohols (4a-g) are readily fragmented to aldehydes (5a-g) on heating with lead tetraacetate/iodine.
- Shankaran, K.,Talekar, D. G.,Rao, A. S.
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p. 408 - 410
(2007/10/02)
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- Photoreactions of α-sulfonyloxyketones
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Earlier work on the photochemistry of α-sulfonyloxyketones uncovered their propensity to form the corresponding α-ketocarbonium ions on photolysis.Typical reactions such as intramolecular cyclizations, carbonium ion rearrangements, and solvent trapping were found.This paper describes an attempt to extend this reaction to a general synthetic technique for polyene cyclizations.During the course of this work two other major reaction pathways were found.The first is an α-keto carbonium ion to acylium ion rearrangement and the second is a photoreduction-elimination process that leads to an α-keto radical rather than the corresponding cation.
- Charlton, James Leslie.,Lai, Hoi Kiong.,Lypka, Gerald Nicholas
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p. 458 - 462
(2007/10/02)
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