- Nickel-Mediated Photoreductive Cross Coupling of Carboxylic Acid Derivatives for Ketone Synthesis**
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A simple visible light photochemical, nickel-catalyzed synthesis of ketones from carboxylic acid-derived precursors is presented. Hantzsch ester (HE) functions as a cheap, green and strong photoreductant to facilitate radical generation and also engages in the Ni-catalytic cycle to restore the reactive species. With this dual role, HE allows for the coupling of a large variety of radicals (1°,2°, benzylic, α-oxy & α-amino) with aroyl and alkanoyl moieties, a new feature in reactions of this type. With both precursors deriving from abundant carboxylic acids, this protocol is a welcome addition to the organic chemistry toolbox. The reaction proceeds under mild conditions without the need for toxic metal reagents or bases and shows a wide scope, including pharmaceuticals and complex molecular architectures.
- Brauer, Jan,Quraishi, Elisabeth,Kammer, Lisa Marie,Opatz, Till
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supporting information
p. 18168 - 18174
(2021/11/30)
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- 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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- 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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- Ketone Synthesis from Benzyldiboronates and Esters: Leveraging α-Boryl Carbanions for Carbon-Carbon Bond Formation
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An alkoxide-promoted method for the synthesis of ketones from readily available esters and benzyldiboronates is described. The synthetic method is compatible with a host of sterically differentiated alkyl groups, alkenes, acidic protons α to carbonyl groups, tertiary amides, and aryl rings having common organic functional groups. With esters bearing α-stereocenters, high enantiomeric excess was maintained during ketone formation, establishing minimal competing racemization by deprotonation. Monitoring the reaction between benzyldiboronate and LiOtBu in THF at 23 °C allowed for the identification of products arising from deborylation to form an α-boryl carbanion, deprotonation, and alkoxide addition to form an "-ate" complex. Addition of 4-trifluoromethylbenzoate to this mixture established the α-boryl carbanion as the intermediate responsible for C-C bond formation and ultimately ketone synthesis. Elucidation of the role of this intermediate leveraged additional bond-forming chemistry and enabled the one-pot synthesis of ketones with α-halogen atoms and quaternary centers with four-different carbon substituents.
- Lee, Boran,Chirik, Paul J.
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supporting information
p. 2429 - 2437
(2020/03/03)
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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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- Nickel-Catalyzed Cross-Coupling of Alkyl Carboxylic Acid Derivatives with Pyridinium Salts via C-N Bond Cleavage
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The electrophile-electrophile cross-coupling of carboxylic acid derivatives and alkylpyridinium salts via C-N bond cleavage is developed. The method is distinguished by its simplicity and steers us through a variety of functionalized ketones in good to excellent yields. Besides acid chlorides, carboxylic acids were also employed as acylating agents, which enabled us to incorporate acid-sensitive functional groups such as MOM, BOC, and acetal. Control experiments with TEMPO revealed a radical pathway.
- Pulikottil, Feba Thomas,Pilli, Ramadevi,Suku, Rohith Valavil,Rasappan, Ramesh
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p. 2902 - 2907
(2020/04/09)
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- Iron-catalyzed urea synthesis: Dehydrogenative coupling of methanol and amines
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Substituted ureas have numerous applications but their synthesis typically requires the use of highly toxic starting materials. Herein we describe the first base-metal catalyst for the selective synthesis of symmetric ureas via the dehydrogenative coupling of methanol with primary amines. Using a pincer supported iron catalyst, a range of ureas was generated with isolated yields of up to 80% (corresponding to a catalytic turnover of up to 160) and with H2 as the sole byproduct. Mechanistic studies indicate a stepwise pathway beginning with methanol dehydrogenation to give formaldehyde, which is trapped by amine to afford a formamide. The formamide is then dehydrogenated to produce a transient isocyanate, which reacts with another equivalent of amine to form a urea. These mechanistic insights enabled the development of an iron-catalyzed method for the synthesis of unsymmetric ureas from amides and amines.
- Lane, Elizabeth M.,Hazari, Nilay,Bernskoetter, Wesley H.
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p. 4003 - 4008
(2018/05/04)
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- Alternative approach toward the generation of benzylic zinc reagent: Direct oxidative addition of active zinc into the carbon-oxygen bond of benzyl mesylates
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The use of highly active zinc, prepared by the Rieke method, for the direct preparation of benzylic zinc mesylate was investigated. The oxidative addition of highly active zinc to benzyl mesylate was easily completed under mild conditions. The resulting benzylic zinc mesylates were employed in subsequent cross-coupling reactions with a broad range of electrophiles, and the formation of the corresponding products was successful.
- Jung, Hye-Soo,Kim, Seung-Hoi
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p. 666 - 670
(2015/03/14)
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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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- THERAPEUTIC FLUOROETHYL UREAS
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Compounds of the formula or a pharmaceutically acceptable salt thereof or a tautomer thereof, wherein A and B are as described herein, are useful for treating conditions afflicting mammals.
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Page/Page column 14
(2008/06/13)
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- Functionalized benzylic magnesium reagents through a sulfur-magnesium exchange
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(Chemical Equation Presented) Switch it: lodobiphenyl thioethers readily undergo an iodine-magnesium exchange followed by, after the addition of tBuOLi, an intramolecular sulfur-magnesium exchange, which provides benzylic magnesium reagents in excellent yield through a fragmentation reaction.
- Stoll, Armin H.,Krasovskiy, Arkady,Knochel, Paul
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p. 606 - 609
(2007/10/03)
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- IMIDAZOLE AND THIAZOLE DERIVATIVES AS ANTIVIRAL AGENTS
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The present invention relates to compounds of the formula (I), wherein R1, R2, A, B, D, E, F, G and Ar are as defined herein, and pharmaceutically acceptable salts thereof, useful in the prevention and treatment of hepatitis C infections.
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Page/Page column 22
(2010/02/15)
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- Reagent-controlled asymmetric homologation of boronic esters by enantioenriched main-group chiral carbenoids
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Putative enantioenriched carbenoid species, (R)-1-chloro-2- phenylethylmagnesium chloride (9) and (S)-1-chloro-2-phenylethyllithium (26), generated in situ by sulfoxide ligand exchange from (-)-(Rs,R)-1- chloro-2-phenylethyl p-tolyl sulfoxide (8), effected the stereocontrolled homologation of boronic esters. sec-Alcohols derived from the product boronates by oxidation with basic hydrogen peroxide exhibited % ee closely approaching that of sulfoxide 8 in examples employing Li-carbenoid 26.
- Blakemore, Paul R.,Marsden, Stephen P.,Vater, Huw D.
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p. 773 - 776
(2007/10/03)
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- N,N-DISUBSTITUTED DIAZOCYCLOALKANES
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N,N-Disubstituted diazocycloalkanes of the formula I (R1=halogen, R2=(C3-C 8)-cycloalkyl, R3=(C1-C4)-alkoxy or (C 1-C4)-haloalkoxy group, m is 1 or 2 and n is 1 or 2, have affinity for serotonergic receptors. These compounds and their enantiomers, diaster
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Page/Page column 15
(2010/02/06)
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- Arylpiperazines having activity at the serotonin 1A receptor
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A series of aryl piperazine compounds are effective pharmaceuticals for the treatment of conditions related to or affected by the serotonin 1A receptor; the compounds are particularly effective antagonists at that receptor, and are particularly useful for alleviating the symptoms of nicotine and tobacco withdrawal.
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- N,N-DISUBSTITUTED DIAZOCYCLOALKANES USEFUL FOR THE TREATMENT OF CNS DISORDERS DUE TO SEROTONERGIC DYSFUNCTION
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N,N-Disubstituted diazocycloalkanes of the formula (I): (R1 = halogen, R2 = (C3-C8)-cycloalkyl, R3 = (C1-C4)-alkoxy or (C1-C4)-haloalkoxy group, m is 1 or 2, n is 1 or 2) have affinity for serotoninergic receptors. These compounds and their enantiomers, diastereoisomers, N-oxides, polymorphs, solvates and pharmaceutically acceptable salts are useful in the treatment of patients with neuromuscular dysfunction of the lower urinary tract and diseases related to 5-HT1A receptor. 1,4-Disubstituted-piperazines (n = 1) are preferred. R1 is preferably F in the 2-position, R2 is preferably cyclohexyl, and R3 is preferably a methoxy or 2,2,2-trifluoroethyl group. Preferably, m = 1.
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- 4-Aryl/cycloalkyl-5-phenyloxazole derivatives as selective COX-2 inhibitors
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A series of 4-aryl/cycloalkyl-5-phenyloxazole derivatives was synthesized and evaluated for their ability to inhibit cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1). These compounds were found to be potent and selective COX-2 inhibitors.
- Hashimoto, Hiromasa,Maeda, Kimiya,Ozawa, Koichi,Haruta, Jun-Ichi,Wakitani, Korekiyo
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- 4-(4-cycloalkyl/aryl-oxazol-5-yl)benzenesulfonamides as selective cyclooxygenase-2 inhibitors: Enhancement of the selectivity by introduction of a fluorine atom and identification of a potent, highly selective, and orally active COX-2 inhibitor JTE-522
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A series of 4-(4-cycloalkyl/aryl-oxazol-5-yl)benzenesulfonamide derivatives were synthesized and evaluated for their abilities to inhibit cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) enzymes. In this series, substituent effects at the ortho position to the sulfonamide group on the phenyl ring were examined. Most substituents reduced or lost both COX-2 and COX-1 activities. In contrast, introduction of a fluorine atom preserved COX-2 potency and notably increased COX1/COX-2 selectivity. This work led to the identification of a potent, highly selective, and orally active COX-2 inhibitor JTE-522 [9d, 4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide], which is currently in phase II clinical trials for the treatment of rheumatoid arthritis, osteoarthritis, and acute pain.
- Hashimoto, Hiromasa,Imamura, Katsuaki,Haruta, Jun-Ichi,Wakitani, Korekiyo
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p. 1511 - 1517
(2007/10/03)
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- Arylpiperazines having activity at the serotonin 1A receptor
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A series of aryl piperazine compounds of the formula: or the pharmaceutically acceptable salts thereof, are effective pharmaceuticals for the treatment of conditions related to or affected by the serotonin 1Areceptor; the compounds are particularly effective antagonists at that receptor, and are particularly useful for alleviating the symptoms of nicotine and tobacco withdrawal.
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- A simple, user-friendly process for the homologation of aldehydes using tosylhydrazone salts
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Aldehydes can be homologated to ketones in moderate to good yields using aryldiazomethanes generated in situ from tosylhydrazones. Chiral aldehydes can be employed with almost complete retention of configuration. The tosylhydrazones can also be generated in situ from the corresponding aldehyde leading to a one-pot process for coupling two different carbonyl compounds to give ketones. (C) 2000 Elsevier Science Ltd.
- Aggarwal, Varinder K.,De Vicente, Javier,Pelotier, Beatrice,Holmes, Ian P.,Bonnert, Roger V.
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p. 10327 - 10331
(2007/10/03)
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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 AND APPLICATION OF IMIDAZOLE DERIVATIVES. SYNTHESIS OF (1-METHYL-1H-IMIDAZOL-2-YL)METHANOL DERIVATIVES AND CONVERSION INTO CARBONYL COMPOUNDS
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(1-methyl-2H-imidazol-2-yl)methanol derivatives ( 4 and 7 ) were prepared by treating carbonyl compounds with 2-lithio-1-methyl-1H-imidazole ( 2 ) or by treating 2-acyl-1H-imidazoles ( 3 ) with organometallic reagents or sodium borohydride.The alcohols ( 4 and 7 ) were convertible into the carbonyl compounds via the corresponding quaternary salts ( 8 and 10 ).The stable (1-methyl-1H-imidazol-2-yl)methanol system, , can be regarded as a masked form of the carbonyl group as well as a synthon of the group.Keywords - (1-methyl-1H-imidazol-2-yl)methanol; 2-acyl-1-methyl-1H-imidazole; carbonyl compound synthesis; β-ketoester; protecting group; latent functionality; symmetric ketone; dihydrojasmone
- Ohta, Shunsaku,Hayakawa, Satoshi,Nishimura, Kazuko,Okamoto, Masao
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p. 1058 - 1069
(2007/10/02)
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- Minor Products in Photoreactions of α-Diketones with Arenes. Abstraction of Hydroxylic Hydrogen by Triplet Carbonyl
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Photochemical reactions of cyclic saturated α-diketones in toluene or p-xylene produce 1:1 adducts as major products and smaller amounts of reduced diketone and bibenzyls, as expected from previous work.In addition, reaction of BOD gave 2percent of the decarbonylation product, p-methylbenzyl cyclohexyl ketone; reaction of camphorquinone gave a mixture of decarbonylation products (10percent total) including saturated and unsaturated monoketones.These compounds were secondary products arising from reaction of photoexcited diketone with the initially formed adducts; quenching andsensitization studies showed that triplet states of α-diketones were involved in both primary and secondary reactions.The decarbonylation products were also formed by reaction of benzophenone triplets or of tert-butoxy radicals with adducts.Deuterium labeling of the adducts was employed to demonstrate that the decarbonylation process involves abstraction of hydroxylic hydrogen.
- Rubin, Mordecai B.,Gutman, Arie L.
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p. 2511 - 2515
(2007/10/02)
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- Metallic Nickel-Mediated Synthesis of Ketones by the Reaction of Benzylic, Allylic, Vinylic, and Pentafluorophenyl Halides with Acid Halides
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Metallic nickel was investigated as a convenient coupling reagent for the synthesis of ketones by the reaction of benzylic, allylic, vinylic, and pentafluorophenyl halides with acid halides at 85 deg C in glyme.A variety of benzylic ketones with functional groups including halogen, cyano, methoxycarbonyl, and hydroxycarbonyl groups were prepared in good yields by this method.The reaction was demonstrated to proceed via organonickel halide intermediates formed by the smooth oxidative addition of benzylic and acyl halides to metallic nickel, which were trapped with electron-deficient olefins. (?-Allyl)nickel halides, prepared in situ at 85 deg C from allylic halides and the nickel, also worked for the preparation of ketones.Vinylic and pentafluorophenyl halides but not alkyl halides reacted with acid halides to give the corresponding ketones in moderate yields.
- Inaba, Shin-ichi,Rieke, Reuben D.
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p. 1373 - 1381
(2007/10/02)
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- α,β-Epoxy Sulfoxides as Useful Intermediates in Organic Synthesis. I. A Novel Synthesis of Dialkyl Ketones and a Synthesis of Aldehydes from Ketones by One Carbon Elongation
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Treatment of α,β-epoxy sulfoxides, prepared from 1-chloroalkyl phenyl sulfoxides with ketones or aldehydes, with sodium benzeneselenolate gives dialkyl ketones or aldehydes in good yields under mild conditions.The mechanism of this reaction and an application of this process to a formal total synthesis of dihydrojasmone are described.
- Satoh, Tsuyoshi,Kaneko, Youhei,Izawa, Takao,Sakata, Kiichi,Yamakawa, Koji
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p. 1983 - 1990
(2007/10/02)
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- A NOVEL SYNTHESIS OF DIALKYL KETONES AND α-SULFENYLATED CARBONYL COMPOUNDS FROM α,β-EPOXY SULFOXIDES
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Treatment of α,β-epoxy sulfoides with excess sodium phenylselenide and various kinds of alkylthiolates gave dialkyl ketones and α-sulfenylated carbonyl compounds, respectively, in good yields under mild conditions.
- Satoh, Tsuyoshi,Kaneko, Youhei,Kumagawa, Takumi,Izawa, Takao,Sakata, Kiichi,Yamakawa, Koji
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p. 1957 - 1960
(2007/10/02)
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- METALLIC NICKEL: A COUPLING REAGENT OF BENZYL HALIDES AND ACYL HALIDES TO YIELD BENZYL KETONES
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Metallic nickel was found to be a convenient reductive coupling reagent for the preparation of benzyl ketones by the reaction of benzyl halides with acyl halides.
- Inaba, Shin-ichi,Rieke, Reuben D.
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p. 2451 - 2452
(2007/10/02)
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