- Synthesis of 1,2,4-Trithiolanes from Thione S-Oxides and Lawesson Reagent at Room Temperature
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The reaction of 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-oxide with Lawesson reagent (L. R.) afforded the corresponding 1,2,4-trithiolane. Thiopivalophenone and thiopivalophenone S-oxides reacted with L. R. at rt to give the corresponding S-sulfide, which further reacted with thiones to afford the corresponding cis-1,2,4-trithiolanes.
- Okuma, Kentaro,Shigetomi, Toshiyuki,Shibata, Shinji,Shioji, Kosei
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- Light-DrivenN-Heterocyclic Carbene Catalysis Using Alkylborates
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Radical-radical coupling, the selective reaction between two different radical species, has contributed to the methodology for connecting bulky units. Light-drivenN-heterocyclic carbene (NHC) organocatalysis is recognized as a state-of-the-art methodology enabling radical-radical coupling. The catalytic process involves forming an acyl azolium intermediate from the NHC catalyst and an acyl donor, followed by single electron reduction of this key intermediate, which is largely dependent on the photoredox catalyst. We designed a radical NHC catalysis in which the direct photoexcitation of a borate to form a high reducing agent facilitated the single electron reduction event. The borate produces an alkyl radical for the single electron transfer process to accomplish the radical-radical coupling. This protocol enables cross-coupling between alkylborates and acyl imidazoles in addition to radical relay-type alkylacylations of alkenes with alkylborates and acyl imidazoles, affording ketones with a broad scope.
- Sato, Yukiya,Goto, Yamato,Nakamura, Kei,Miyamoto, Yusuke,Sumida, Yuto,Ohmiya, Hirohisa
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p. 12886 - 12892
(2021/10/29)
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- A Fast and General Route to Ketones from Amides and Organolithium Compounds under Aerobic Conditions: Synthetic and Mechanistic Aspects
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We report that the nucleophilic acyl substitution reaction of aliphatic and (hetero)aromatic amides by organolithium reagents proceeds quickly (20 s reaction time), efficiently, and chemoselectively with a broad substrate scope in the environmentally responsible cyclopentyl methyl ether, at ambient temperature and under air, to provide ketones in up to 93 % yield with an effective suppression of the notorious over-addition reaction. Detailed DFT calculations and NMR investigations support the experimental results. The described methodology was proven to be amenable to scale-up and recyclability protocols. Contrasting classical procedures carried out under inert atmospheres, this work lays the foundation for a profound paradigm shift of the reactivity of carboxylic acid amides with organolithiums, with ketones being straightforwardly obtained by simply combining the reagents under aerobic conditions and with no need of using previously modified or pre-activated amides, as recommended.
- Ghinato, Simone,Territo, Davide,Maranzana, Andrea,Capriati, Vito,Blangetti, Marco,Prandi, Cristina
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p. 2868 - 2874
(2021/01/21)
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- N-Heterocyclic Carbene-Catalyzed Decarboxylative Alkylation of Aldehydes
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We found that N-heterocyclic carbene catalysis promoted the unprecedented decarboxylative coupling of aryl aldehydes and tertiary or secondary alkyl carboxylic acid-derived redox-active esters to produce aryl alkyl ketones. The mild and transition-metal-free reaction conditions are attractive features of this method. The power of this protocol was demonstrated by the functionalization of pharmaceutical drugs and natural product. A reaction pathway involving single electron transfer from an enolate form of Breslow intermediate to a redox ester followed by recombination of the resultant radical pair to form a carbon-carbon bond is proposed.
- Ishii, Takuya,Kakeno, Yuki,Nagao, Kazunori,Ohmiya, Hirohisa
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supporting information
p. 3854 - 3858
(2019/04/25)
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- Cp?Co(III)-Catalyzed C-H Alkylation with Maleimides Using Weakly Coordinating Carbonyl Directing Groups
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A novel protocol for ortho-C-H alkylation of aromatic and heteroaromatic ketones and esters under Cp?Co(III) catalysis has been developed for the first time. The reaction proceeds through initial cyclometalation via weak chelation-assisted C-H bond activation, followed by coordination of activated alkene, insertion between Co-C, and protodemetalation.
- Mandal, Rajib,Emayavaramban, Balakumar,Sundararaju, Basker
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supporting information
p. 2835 - 2838
(2018/05/29)
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- Synthesis of ketones via organolithium addition to acid chlorides using continuous flow chemistry
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An efficient method for the synthesis of ketones using organolithium and acid chlorides under continuous flow conditions has been developed. In contrast to standard batch chemistry, over-addition of the organolithium to the ketone for the formation of the undesired tertiary alcohol has been minimised representing a direct approach toward ketones.
- Moon, Soo-Yeon,Jung, Seo-Hee,Bin Kim,Kim, Won-Suk
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p. 79385 - 79390
(2015/10/06)
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- Chemoselective oxidation by electronically tuned nitroxyl radical catalysts
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Electronic tuning: Nitroxyl radical 1 is shown to be an efficient catalyst for the oxidation of secondary alcohols, and promotes oxidation through an oxoammonium species which is highly reactive because of the adjacent electron-withdrawing ester groups. Chemoselective oxidation of benzylic alcohols in the presence of aliphatic alcohols is observed and is proposed to proceed by a rate-determining hydride transfer. Copyright
- Hamada, Shohei,Furuta, Takumi,Wada, Yoshiyuki,Kawabata, Takeo
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supporting information
p. 8093 - 8097
(2013/08/23)
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- Synthesis of sterically hindered ketones from aldehydes via O-silyl oximes
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A mild and efficient method to synthesize sterically hindered ketones from aldehydes via O-silyl oximes was developed. Treatment of O-triphenylsilylated oximes with alkyl iodides in the presence of triethyl borane afforded the corresponding ketones.
- Kim, Joong-Gon,Mishra, Mithilesh Kumar,Jang, Doo Ok
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experimental part
p. 3527 - 3529
(2012/08/29)
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- Synthesis of α-indanones via intramolecular direct arylation with cyclopropanol-derived homoenolates
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A palladium-catalysed, tandem cyclopropanol rearrangement and direct arylation approach for the synthesis of 1-indanones is reported. The reaction is generally high yielding, uses oxygen as the terminal oxidant and tolerates a range of functional groups on the aryl ring.
- Rosa, David,Orellana, Arturo
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p. 1922 - 1924
(2012/03/11)
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- Facile preparation of aromatic ketones from aromatic bromides and arenes with aldehydes
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Aromatic ketones were efficiently prepared in good yields by the reactions of aryl bromides with n-BuLi, followed by the reactions with aromatic aldehydes or aliphatic aldehydes and the subsequent treatment with molecular iodine and K2CO3, in a one-pot method. The same treatment of arenes, instead of aromatic bromides, also provided the corresponding aromatic ketones in good yields. Using these methods, various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatics and electron-deficient aromatics could be prepared efficiently by a simple, transition-metal-free, and therefore environmentally benign experimental procedure.
- Ushijima, Sousuke,Dohi, Souya,Moriyama, Katsuhiko,Togo, Hideo
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scheme or table
p. 1436 - 1442
(2012/03/09)
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- Practical one-pot preparation of ketones from aryl and alkyl bromides with aldehydes and DIH via Grignard reagents
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Various diaryl ketones, alkyl aryl ketones, and dialkyl ketones were efficiently prepared in good yields by the reactions of the Grignard reagents derived from aryl or alkyl bromides, followed by the reactions with aromatic or aliphatic aldehydes and the subsequent treatment with 1,3-diiodo-5,5- dimethylhydantoin and K2CO3, in a one-pot method. The same treatment of aromatic bromides bearing electron-withdrawing groups, such as ester, nitrile, ketone, and nitro groups with i-PrMgCl·LiCl or PhMgCl instead of Mg, also provided the corresponding diaryl and alkyl aryl ketones in good yields. The above methods are simple and practical transition-metal-free methods for the preparation of various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatic groups and electron-deficient aromatic groups, as well as dialkyl ketones.
- Dohi, Souya,Moriyama, Katsuhiko,Togo, Hideo
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experimental part
p. 6557 - 6564
(2012/08/27)
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- Development of decarboxylative coupling processes for the synthesis of azomethines and ketones
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A bimetallic catalyst system has been developed that allows the synthesis of azomethines by a one-pot three-component decarboxylative coupling, starting from simple, nontoxic precursors, i.e. potassium α-oxo carboxylates, aryl halides and primary amines. In the presence of 15 mol-% copper/phenanthroline and 1 mol-% Pd/dppf, a wide range of valuable imines is conveniently accessible in high yields at 100 °C, an unprecedentedly low temperature for redox-neutral decarboxylative cross-coupling reactions. Hydrogenation of the azomethine products leads to secondary amines. Alternatively, they can be hydrolyzed in situ to aryl ketones. The resulting ketone synthesis via azomethine intermediates is also of interest as it gives higher yields at much lower temperatures than the direct decarboxylative coupling of α-oxo carboxylates with aryl halides. A convenient synthesis of azomethines by a one-pot three-component decarboxylative coupling, starting from potassium α-oxo carboxylates, aryl halides and primary amines is described. Combined with in situ hydrolysis, ketones are obtained. Thisamine-mediated ketone synthesis gives higher yields at lower temperatures than the direct coupling of α-oxo carboxylates. Copyright
- Collet, Florence,Song, Bingrui,Rudolphi, Felix,Goossen, Lukas J.
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p. 6486 - 6501
(2011/12/05)
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- Biaryl and aryl ketone synthesis via Pd-catalyzed decarboxylase coupling of carboxylate salts with aryl triflates
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A bimetallic catalyst system has been developed that for the first time allows the decarboxylative crosscoupling of aryl and acyl carboxylates with aryl triflates. In contrast to aryl halides, these electrophiles give rise to non-coordinating anions as byproducts, which do not interfere with the decarboxylation step that leads to the generation of the carbon nucleophilic crosscoupling partner. As a result, the scope of carboxylate substrates usable in this transformation was extended from ortho-substituted or otherwise activated derivatives to a broad range of ortho-, meta-, and para-substituted aromatic carboxylates. Two alternative protocols have been optimized, one involving heating the substrates in the presence of CuI/1,10- phenanthroline (10-15 mol %) and PdI2/phosphine (23 mol%) in NMP for 1-24 h, the other involving CuI/l,10-phenanthroline (615mol%) and PdBr2/Tol-BINAP (2 mol % ) in NMP using microwave heating for 5-10 min. While most products are accessible using standard heating, the use of microwave irradiation was found to be beneficial especially for the conversion of non-activated carboxylates with functionalized aryl triflates. The synthetic utility of the transformation is demonstrated with 48 examples showing the scope and limitations of both protocols. In mechanistic studies, the special role of microwave irradiation is elucidated, and further perspectives of decarboxylase crosscouplings are discussed.
- Goossen, Lukas J.,Linder, Christophe,Rodriguez, Nuria,Lange, Paul P.
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supporting information; experimental part
p. 9336 - 9349
(2010/04/03)
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- Catalyst-free alkanoylation of aromatic rings via arylstannanes. Scope and limitations
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The reaction of alkanoyl chlorides with arylstannanes in 1,2-dichlorobenzene (180 °C) is a simple and direct route for the catalyst-free and regioselective synthesis of tertiary alkyl aryl ketones in good to excellent isolated yields (55-77%). Nevertheles
- Lo Fiego, Marcos J.,Lockhart, María T.,Chopa, Alicia B.
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supporting information; experimental part
p. 3674 - 3678
(2010/01/18)
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- PROCESS FOR PREPARING KETONES FROM ALPHA-OXO CARBOXYLATES AND ARYL BROMIDES
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A process for preparing ketones of the general formula (III) where R is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted alkyl radical or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, andR1 is an optionally substituted carbocyclic aromatic radical having 6 to 24 carbon atoms or an optionally substituted heteroaromatic radical having 5 to 24 carbon atoms, by reacting alpha-oxo carboxylates of the general formula (I) wherein n and m is a number in the range from 1 to 6, M(m+) is a cation, and R has the meaning indicated for formula (III), with aryl bromides of the general formula (II) [in-line-formulae]R1—Br ??(II)[/in-line-formulae] where R1 has the meaning indicated for formula (III), in the presence of two transition metals or compounds thereof as catalyst, is described.
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Page/Page column 2-3
(2009/09/08)
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- Synthesis of ketones from α-oxocarboxylates and aryl bromides by Cu/Pd-catalyzed decarboxylative cross-coupling
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(Chemical Equation Presented) The power of two metals: A Pd/Cu catalyst system mediates the in situ formation of acyl nucleophiles by decarboxylation of readily accessible and stable salts of α-oxocarboxylic acids and their cross-coupling with aryl or heteroaryl bromides to give ketones. The reaction may be usedin the presence of many functional groups and provides good yields.
- Goossen, Lukas J.,Rudolphi, Felix,Oppel, Christoph,Rodriguez, Nuria
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p. 3043 - 3045
(2008/12/23)
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- Reaction of ketone hydrazones with diselenium dihalides: Simple synthesis of Δ3-1,3,4-selenadiazolines and 2,5-diarylselenophenes
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Sterically congested cis- and trans-Δ3-1,3,4- selenadiazolines were isolated by one-pot reactions of ketone hydrazones with diselenium dibromide, which suggested the in situ formation of selone and diazoalkane intermediates. The thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines. The reaction of acetophenone hydrazones with diselenium dibromide afforded 2,5- diarylselenophenes in moderate yields. The reaction proceeded through selone intermediates.
- Okuma, Kentaro,Izaki, Toshiharu,Kubo, Kento,Shioji, Kosei,Yokomori, Yoshinobu
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p. 1121 - 1126
(2007/10/03)
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- First isolation of cis- and trans-1,3,4-selenadiazolines from pivarophenone hydrazones
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Sterically congested cis- and trans-1,3,4-selenadiazolines were isolated by one-pot reaction of pivalophenone hydrazones with diselenium dibromide, which suggested in situ formation of selenoketone and diazoalkane intermediates. Thermolysis of these compounds gave symmetrical olefins, whereas oxidation afforded the corresponding azines.
- Okuma, Kentaro,Kubo, Kento,Yokomori, Yoshinobu
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p. 299 - 302
(2007/10/03)
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- Facile synthesis of pivalophenones by an ultrasound assisted iodine catalysed Friedel-Crafts acylation reaction
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The use of ultrasound in the acylation reactions of various aromatics and heterocyclics with pivaloyl chloride in the presence of catalytic amount of iodine, without any added solvent and at room temperature, gives excellent yields of the respective pivalophenones in a short reaction time.
- Gopalakrishnan, Geetha,Anandhi,Narasimhan
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p. 1197 - 1198
(2007/10/03)
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- A facile synthesis of pivalophenones by ultrasound assisted AlCl3 catalysed Friedel-Crafts reaction
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Pivalophenones have been prepared by the acylation reaction of various aromatic and heterocyclic compounds with pivaloyl chloride using AlCl3 as catalyst under sonochemical conditions in a short reaction time and in reasonable yields.
- Gopalakrishnan, Geetha,Anandhi,Narasimhan
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p. 1194 - 1196
(2007/10/03)
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- NEW WAYS OF GENERATING ORGANOTIN REACTIVE INTERMEDIATES FOR ORGANIC SYSNTHESIS
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Progress in generating and applying two important organotin reactive species for organic synthesis is reported. - Stannyl radicals R3Sn., at present the most used tools for free radical synthesis of complicated target molecules, are generally obtained from the hydrides R3SnH.In a number of cases, however, this is a drawback because of the high radical scavenging power of the latter.New ways of generating R3Sn., decoupling them from the presence of R3SnH, are developed and discussed: the spontaneous thermal dissociation of distannanes with bulky substituents, the thermal fragmentation of bistannyl benzpinacols, the ketone sensitized mild photolysis of simple distannanes, and the mild photolysis of benzyltin compounds such as 9-stannyl-9,10-dihydro anthracene.Examples of advantageous applications, also in combinations with adjusted H donors, are given. - Stannyl cations R3Sn(+) are used as superior leaving groups in electrophilic aromatic ipso substitution.Examples for their application under very mild conditions include the considerable broadening of the scope of the Friedel-Crafts acylation, the Vilsmeier formylation, sulfinations, and sulfonations.The directing influence of certain other substituents can be overcome by this ipso substitution.
- Neumann, Wilhelm P.,Hillgaertner, Horst,Baines, Kim M.,Dicke, Rita,Vorspohl, Klaus,et al.
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p. 951 - 960
(2007/10/02)
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- A Convenient Procedure for Complete Methylation of the α-Positions of Some Ketones
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2,2,6,6-Tetramethylcyclohexanone (2a), Pivalophenone (4a), and other complete methylated ketones can be prepared by a simple procedure.Therefore the ketone was treated with methyl iodide and powdered KOH in the presence of catalytical amounts of crown-6.
- Lissel, Manfred,Neumann, Beate,Schmidt, Stefan
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p. 263 - 264
(2007/10/02)
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- Aroyl Anion Trapping Reactions. A Preliminary Study of Direct Nucleophilic Aroylation by Means of Low Temperature, in situ (CH3)nC6H5 nLi/CO Systems.
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Results of studies of the in situ nucleophilic aroylation of PhCO2Me, Me3CCO2Me and Ph2CO by several low temperature ArLi/CO systems (Ar = C6H5, p-CH3C6H4, o-CH3C6H4, 2,6-(CH3)2C6H3 and 2,4,6-(CH3)3C6H2) are reported.The experiments with C6H5Li were unsuccessfull and the best results were obtained with 2,6-(CH3)2-C6H3Li.
- Seyferth, Dietmar,Wang, Wei-Liang,Hui, Rihard C.
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p. 1651 - 1654
(2007/10/02)
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- Iminodimethylene di-tert-alkylophenones and phenols
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Substituted-iminodimethylene-di-tert-alkylophenones, e.g., 4", 4"'-methyliminodimethylene-dipivalophenone, are prepared by treating a corresponding α-halo-p-tert-alkanoyl toluene with a substituted amine. The phenylcarbinols are prepared from the corresponding phenones and both the phenones and the phenylcarbinols are useful as hypolipidemic agents.
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- Thiodimethylene bis(pivalophenone)
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Substituted or unsubstituted thiodimethylene bis(pivalophenone), e.g., 4',4'"-(thiodimethylene) bis(pivalophenone) are prepared by treating a corresponding α-halo-p-tert-alkanoyl toluene with an alkali metal sulfide and are useful as hypolipidemic agents.
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- Acyl benzyl ethers
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Acyl substituted or unsubstituted benzyl ethers, e.g., p-(phenoxymethyl)pivalophenone, are prepared by reacting a corresponding α-bromo-p-pivaloyl toluene with a corresponding phenol and are useful as hypolipidemic agents.
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- α-Bromo-pivaloyl toluenes
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Acyl substituted phenyl alkanoic acids, e.g. p-pivaloyl phenyl acetic acid, are prepared by hydrolyzing p-pivaloyl phenyl acetonitriles and are useful as hypolipidemic agents.
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- Bis-substituted benzyl acetic acids
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Bis-substituted benzyl acetic acids, e.g., bis-(p-pivaloylbenzyl)acetic acid, are prepared by hydrolyzing and decarboxylating a corresponding bis-(p-pivaloylbenzyl)malonic acid diethyl ester and are useful as hypolipidemic agents.
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