- Direct Formation of (Haloaryl)copper Nucleophiles from Haloiodobenzenes and Active Copper
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(o-Halophenyl)-, (m-halophenyl)-, and (p-halophenyl)copper reagents have been formed in moderate to high yields at room temperature from active copper and the corresponding haloiodobenzenes.These reagents have been cross-coupled with a variety of alkyl and acyl halides to produce the respective haloarenes and haloaryl ketones.Remarkably, (o-fluorophenyl)- and (o-chlorophenyl)copper are produced in good yields by this procedure without undergoing elimination to form benzyne making this approach a convenient method for generating o-halophenyl nucleophiles.
- Ebert, Greg W.,Pfennig, Deborah R.,Suchan, Scott D.,Donovan, Thomas A.,Aouad, Emmanuel,et al.
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- Palladium-phosphinous acid-catalyzed cross-coupling of aliphatic and aromatic acyl chlorides with boronic acids
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The cross-coupling of aromatic and aliphatic acyl chlorides with arylboronic acids in the presence of 2.5 mol % of (t-Bu2POH)2PdCl2 (POPd) provides rapid access to ketones that are obtained in up to 93% yield. This palladium-phosphinous acid-catalyzed reaction is completed within 10 min when microwave irradiation is used, and it overcomes typical drawbacks of Friedel-Crafts acylation procedures such as harsh reaction conditions, untunable regiocontrol, and low substrate scope.
- Ekoue-Kovi, Kekeli,Xu, Hanhui,Wolf, Christian
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- Microwave promoted palladium-catalyzed phenylation of aroyl chlorides and sodium tetraphenylborate
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A rapid and efficient method for synthesis of unsymmetrical ketones involves reaction of sodium tetraphenylborate with aroyl chlorides in the presence of catalytic amount Pd(PPh3)2Cl2 under microwave irradiation to give the corresponding phenyl ketones 3a-j in 87-98% yield.
- Wang,Wei,Hu,Liu,Yang
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- Microwave-assisted cross-coupling reaction of sodium tetraphenylborate with aroyl chlorides on palladium-doped KF/Al2O3
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A palladium-catalysed cross-coupling reaction of sodium tetraphenylborate with aroyl chloride using KF/Al2O3 as supported reagents in the presence of acetone under microwave-irradiation conditions gives unsymmetrical ketones in good high yield.
- Wang, Jin-Xian,Yang, Yihua,Wei, Bangguo,Hu, Yulai,Fu, Ying
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- Ruthenium Hydride Complex Supported on Gold Nanoparticle Cored Triazine Dendrimers for C-C Coupling Reactions
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In this work, the unusual ability of a ruthenium hydride catalyst, [RuHCl(PPh3)3CO], supported on gold nanoparticle cored triazine dendrimers in the Suzuki-Miyaura cross-coupling reaction and also in the synthesis of diaryl ketones is reported. [Ru-H@AuNPs-TD] was characterized by Fourier transform infrared spectroscopy, CHNS, TEM, SEM, ICP, and TGA analyses. The ruthenium hydride catalyst was used as a heterogeneous catalyst for the C-C coupling reactions of aryl halides with phenylboronic acids, and the biphenyl derivatives were produced in good to excellent yields. On the other hand, this catalytic system was applied for synthesis of diaryl ketones by the reaction of phenylboronic acids with substituted benzaldehydes. Moreover, this catalyst can be well-dispersed in the reaction medium, conveniently separated from the reaction mixture, and reused several times without significant loss of its activity.
- Daneshvar, Anahita,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Khalili, Akram
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- Synthesis of Farnesol Analogues through Cu(I)-Mediated Displacements of Allylic THP Ethers by Grignard Reagents
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The synthesis of a family of farnesol analogues, incorporating aromatic rings, has been achieved in high yields through the development of a regioselective coupling of allylic tetrahydropyranyl ethers with organometallic reagents. The allylic THP group is displaced readily by Grignard reagents in the presence of Cu(I) halides but is stable in the absence of added copper. Thus, an allylic THP group can fulfill its traditional role as a protecting group or serve as a leaving group depending on reaction conditions. An improved synthesis of (2E,6E)-10,11-dihydrofarnesol also has been accomplished using this methodology, and some preliminary studies on the reactivity and regioselectivity of THP ether displacements were conducted. The farnesol analogues reported herein may be useful probes of the importance of nonbonding interactions in enzymatic recognition of the farnesyl chain and allow development of more potent competitive inhibitors of enzymes such as farnesyl protein transferase.
- Mechelke, Mark F.,Wiemer, David F.
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- AIBN initiated functionalization of the benzylic sp3 C[sbnd]H and C[sbnd]C bonds in the presence of dioxygen
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A sp3 C[sbnd]H bond functionalization and C[sbnd]C bond cleavage were realized by AIBN/O2 catalyst system, providing a series of benzophenones under mild reaction conditions. The mechanistic study shows that a peroxide intermediate is involved in this transformation, and in the case of diphenylmethanes, the sp3 C[sbnd]C bond is cleaved through the peroxide rearrangement, which might provides a new way to cleave relatively strong C[sbnd]C bond and be applied to more general C[sbnd]C bond activation.
- Hu, Yingying,Shao, Yu,Zhang, Shuwei,Yuan, Yuan,Sun, Zheng,Yuan, Yu,Jia, Xiaodong
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Read Online
- Synthesis of biaryl ketones by arylation of Weinreb amides with functionalized Grignard reagents under thermodynamic controlvs.kinetic control ofN,N-Boc2-amides
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A highly efficient method for chemoselective synthesis of biaryl ketones by arylation of Weinreb amides (N-methoxy-N-methylamides) with functionalized Grignard reagents is reported. This protocol offers rapid entry to functionalized biaryl ketones after Mg/halide exchange with i-PrMgCl·LiCl under operationally-simple and practical reaction conditions. The scope of the method is highlighted in >40 examples, including bioactive compounds and pharmaceutical derivatives. Collectively, this transition-metal-free approach offers a major advantage over the recently established cross-coupling of amides by oxidative addition of N-C(O) bonds. Considering the utility of amide acylation reactions in modern synthesis, we expect that this method will be of broad interest.
- Li, Guangchen,Szostak, Michal
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supporting information
p. 3827 - 3831
(2020/06/03)
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- Kinetically Controlled, Highly Chemoselective Acylation of Functionalized Grignard Reagents with Amides by N?C Cleavage
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The direct transition-metal-free acylation of amides with functionalized Grignard reagents by highly chemoselective N?C cleavage under kinetic control has been accomplished. The method offers rapid and convergent access to functionalized biaryl ketones through transient tetrahedral intermediates. The direct access to functionalized Grignard reagents by in situ halogen–magnesium exchange promoted by the versatile turbo-Grignard reagent (iPrMgCl?LiCl) permits excellent substrate scope with respect to both the amide and Grignard coupling partners. These reactions enable facile, operationally simple and chemoselective access to tetrahedral intermediates from amides under significantly milder conditions than chelation-controlled intermediates. This novel direct two-component coupling sets the stage for using amides as acylating reagents in an alternative paradigm to the metal-chelated approach, acyl metals and Weinreb amides.
- Li, Guangchen,Szostak, Michal
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supporting information
p. 611 - 615
(2020/01/02)
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- Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
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Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
- Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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p. 11823 - 11838
(2019/10/02)
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- Hydrogen bond directed aerobic oxidation of amines via photoredox catalysis
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An application of H-bonding interactions for directing the α-C-H oxidation of amines to amides and amino-ketones catalyzed by an organic photocatalyst is reported. The high efficiency of this method is demonstrated by the aerobic oxidation of pyrrolidines, diarylamines and benzylamines bearing urea groups with high yields and a wide substrate scope.
- Wang, Hongyu,Man, Yunquan,Wang, Kaiye,Wan, Xiuyan,Tong, Lili,Li, Na,Tang, Bo
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supporting information
p. 10989 - 10992
(2018/10/08)
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- A general approach to intermolecular carbonylation of arene C-H bonds to ketones through catalytic aroyl triflate formation
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The development of metal-catalysed methods to functionalize inert C-H bonds has become a dominant research theme in the past decade as an approach to efficient synthesis. However, the incorporation of carbon monoxide into such reactions to form valuable ketones has to date proved a challenge, despite its potential as a straightforward and green alternative to Friedel-Crafts reactions. Here we describe a new approach to palladium-catalysed C-H bond functionalization in which carbon monoxide is used to drive the generation of high-energy electrophiles. This offers a method to couple the useful features of metal-catalysed C-H functionalization (stable and available reagents) and electrophilic acylations (broad scope and selectivity), and synthesize ketones simply from aryl iodides, CO and arenes. Notably, the reaction proceeds in an intermolecular fashion, without directing groups and at very low palladium-catalyst loadings. Mechanistic studies show that the reaction proceeds through the catalytic build-up of potent aroyl triflate electrophiles.
- Kinney, R. Garrison,Tjutrins, Jevgenijs,Torres, Gerardo M.,Liu, Nina Jiabao,Kulkarni, Omkar,Arndtsen, Bruce A.
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p. 193 - 199
(2018/02/06)
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- Preparation method of ketoprofen
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The invention discloses a preparation method of ketoprofen. The method takes m-bromobenzoic acid and benzene as starting raw materials, and the ketoprofen is prepared through the steps of acylating, protecting a carbonyl group, taking a Grignard reagent, reacting with propylene oxide, oxidizing, de-protecting and the like. The method disclosed by the invention has the characteristics of short reaction route, easiness of obtaining the raw materials, high yield and low cost.
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Paragraph 0034; 0048; 0049
(2017/07/14)
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- UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-Aryl shift cascade reactions
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UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.
- Zheng, Lewei,Huang, Hongli,Yang, Chao,Xia, Wujiong
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supporting information
p. 1034 - 1037
(2015/03/30)
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- Palladium(II)-catalyzed desulfitative synthesis of aryl ketones from sodium arylsulfinates and nitriles: Scope, limitations, and mechanistic studies
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A fast and efficient protocol for the palladium(II)-catalyzed production of aryl ketones from sodium arylsulfinates and various organic nitriles under controlled microwave irradiation has been developed. The wide scope of the reaction has been demonstrated by combining 14 sodium arylsulfinates and 21 nitriles to give 55 examples of aryl ketones. One additional example illustrated that, through the choice of the nitrile reactant, benzofurans are also accessible. The reaction mechanism was investigated by electrospray ionization mass spectrometry and DFT calculations. The desulfitative synthesis of aryl ketones from nitriles was also compared to the corresponding transformation starting from benzoic acids. Comparison of the energy profiles indicates that the free energy requirement for decarboxylation of 2,6-dimethoxybenzoic acid and especially benzoic acid is higher than the corresponding desulfitative process for generating the key aryl palladium intermediate. The palladium(II) intermediates detected by ESI-MS and the DFT calculations provide a detailed understanding of the catalytic cycle. (Figure Presented).
- Skillinghaug, Bobo,Sk?ld, Christian,Rydfjord, Jonas,Svensson, Fredrik,Behrends, Malte,S?vmarker, Jonas,Sj?berg, Per J. R.,Larhed, Mats
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p. 12018 - 12032
(2015/01/16)
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- Synthesis of structurally diverse diarylketones through the diarylmethyl sp3 C-H oxidation
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Under open-flask conditions, an efficient method to assemble a series of diversely functionalized diarylketones in the presence of commercially available NBS has been developed. Yields of up to 99% have been achieved employing diarylmethanes as starting material. Based on 18O-labeled experiment, the addition of stoichiometric water eventually leads to excellent yields in all carbonylation cases.
- He, Chao,Zhang, Xiaohui,Huang, Ruofeng,Pan, Jing,Li, Jiaqiang,Ling, Xuege,Xiong, Yan,Zhu, Xiangming
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p. 4458 - 4462
(2014/08/05)
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- Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones
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In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.
- Akhbar, Ahmed R.,Chudasama, Vijay,Fitzmaurice, Richard J.,Powell, Lyn,Caddick, Stephen
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supporting information
p. 743 - 746
(2014/01/06)
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- Microwave-assisted facile and rapid friedel-crafts benzoylation of arenes catalyzed by bismuth trifluoromethanesulfonate
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The catalytic activity of metal triflates was investigated in Friedel-Crafts benzoylation under microwave irradiation. Friedel-Crafts benzoylation with benzoyl chloride of a variety of arenes containing electron-rich and electron-poor rings using bismuth triflate under microwave irradiation is described. This method allows the preparation of aryl ketones under solventless conditions in good to excellent yields and short reaction time. Bismuth triflate was easily recovered and reused five times without significant loss of the catalytic activity.
- Tran, Phuong Hoang,Hansen, Poul Erik,Pham, Thuy Thanh,Huynh, Vy Thanh,Huynh, Vy Hieu,Thi Tran, Thao Du,Huynh, Thanh Van,Le, Thach Ngoc
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p. 2921 - 2929
(2014/10/15)
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- Similar or totally different: The control of conjugation degree through minor structural modifications, and deep-blue aggregation-induced emission luminogens for non-doped OLEDs
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Four 4,4′-bis(1,2,2-triphenylvinyl)biphenyl (BTPE) derivatives, 4,4′-bis(1,2,2-triphenylvinyl)biphenyl, 2,3′-bis(1,2,2- triphenylvinyl)biphenyl, 2,4′-bis(1,2,2-triphenylvinyl)biphenyl, 3,3′-bis(1,2,2-triphenylvinyl)biphenyl and 3,4′-bis(1,2,2- triphenylvinyl)biphenyl (oTPE-mTPE, oTPE-pTPE, mTPE-mTPE, and mTPE-pTPE, respectively), are successfully synthesized and their thermal, optical, and electronic properties fully investigated. By merging two simple tetraphenylethene (TPE) units together through different linking positions, the π-conjugation length is effectively controlled to ensure the deep-blue emission. Because of the minor but intelligent structural modification, all the four fluorophores exhibit deep-blue emissions from 435 to 459 nm with Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of, respectively, (0.16, 0.14), (0.15, 0.11), (0.16, 0.14), and (0.16, 0.16), when fabricated as emitters in organic light-emitting diodes (OLEDs). This is completely different from BTPE with sky-blue emission (0.20, 0.36). Thus, these results may provide a novel and versatile approach for the design of deep-blue aggregation-induced emission (AIE) luminogens. Copyright
- Huang, Jing,Sun, Ning,Dong, Yongqiang,Tang, Runli,Lu, Ping,Cai, Ping,Li, Qianqian,Ma, Dongge,Qin, Jingui,Li, Zhen
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p. 2329 - 2337
(2013/07/19)
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- The synthesis and properties of vinyl substituted naphthopyrans and their styrene copolymers
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A comprehensive series of mono-, di- and tri-bromo-3H-naphtho[2,1-b]pyrans was synthesised by the traditional union of a 2-naphthol with an alkynol. The bromine atom(s) in these naphthopyrans was readily replaced by a vinyl group using a Suzuki coupling reaction with vinyl boronic anhydride pyridine complex. The efficiency of the Suzuki vinylation reaction decreases with the increasing number of bromine atoms to be substituted. The vinylnaphthopyrans served as styrene analogues and readily underwent a thermally initiated free radical addition co-polymerisation with styrene to efficiently afford low molecular weight poly(styrene-co-naphthopyrans). The photochromic response of the bromonaphthopyrans and vinylnaphthopyrans followed the established colour-structure relationships for photochromic naphthopyrans. The photochromic response of toluene solutions of the poly(styrene-co-naphthopyrans) was characterised by a hypsochromic shift of the λmax relative to that recorded for the vinylnaphthopyran monomers. Increased half-lives were noted for the copolymers derived from the bis- and tris-vinylnaphthopyrans where some degree of crosslinking was expected. A further hypsochromic shift in λmax resulted for the thin films of the poly(styrene-co- naphthopyrans). Of particular note was the behaviour of the 3-(2-vinylphenyl)-3- phenylnaphthopyran which gave the typical yellow colour of the photomerocyanine coupled with the predictable large half-life. However, all photochromism of this naphthopyran was lost upon polymerisation suggesting that an alternative pathway supervenes in the expected polymerisation sequence.
- Blackwell, Catherine J.,Gabbutt, Christopher D.,Guthrie, James T.,Heron, B. Mark
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experimental part
p. 408 - 420
(2012/08/28)
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- Synthesis of ketones by palladium-catalysed desulfitative reaction of arylsulfinic acids with nitriles
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Palladium-catalysed desulfitative addition of arylsulfinic acids to aryl and alkyl nitriles with 2,2′-bipyridine as a ligand afforded a variety of aryl ketones via hydrolysis of ketimine intermediates.
- Miao, Tao,Wang, Guan-Wu
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supporting information; experimental part
p. 9501 - 9503
(2011/10/01)
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- Intermolecular N-heterocyclic carbene catalyzed hydroacylation of arynes
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A formal introduction: The conceptually new N-heterocyclic carbene catalyzed formal insertion of arynes into the Cformyl-H bond of aldehydes demonstrates the compatibility of nucleophilic NHCs with electrophilic arynes. This NHC-catalyzed hydroacylation of arynes allows the conversion of aliphatic, α,β-unsaturated, and aromatic aldehydes into aryl ketones; 27 examples and a preliminary mechanistic investigation are provided. Copyright
- Biju, Akkattu T.,Glorius, Frank
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supporting information; experimental part
p. 9761 - 9764
(2011/03/16)
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- Direct reaction of aryl iodides with activated aluminium powder and reactions of the derived aryl sesquiiodides
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High temperature (110-120 °C) direct reaction of ArI (Ar = Ph, 1-C 10H7, 3-Tol) with aluminium powder in the presence of HgCl2 (1 mol%) or liquid gallium metal (10mol%) leads to quantitative conversion to the aryl sesquiiodides Al2Ar3I3. The latter, highly Lewis acidic, compounds are effective in opening of cyclic ethers and direct ester to amide conversions. Georg Thieme Verlag Stuttgart.
- Tang, Xiaoping,Rawson, Daniel,Woodward, Simon
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experimental part
p. 636 - 638
(2010/09/18)
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- INHIBITORS OF CYSTEINE PROTEASES AND METHODS OF USE THEREOF
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The present invention relates to semicarbazone or thiosemicarbazone inhibitors of cysteine proteases and methods of using such compounds to prevent and treat protozoan infections such as trypanosomiasis, malaria and leishmaniasis. The compounds also find use in inhibiting cysteine proteases associated with carcinogenesis, including cathepsins B and L.
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Page/Page column 19
(2009/04/24)
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- Ag-catalyzed stereoselective cyclohexadienyl transfer: A novel entry into arylphenylmethanols
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The letter describes a novel concept for the synthesis of biologically important arylphenylmethanols. Stereoselective cyclohexadienyl transfer from 1,4-cyclohexadienyltributyltin to various aromatic aldehydes using AgOTf/BINAP as a catalyst precursor provides 1,4-cyclohexadienylphen-ylmethanols that are readily oxidized to the corresponding arylphenylmethanols. Fifteen examples are presented.
- Umeda, Rui,Studer, Armido
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supporting information; experimental part
p. 993 - 996
(2009/04/07)
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- Design, synthesis, and biochemical evaluation of novel cruzain inhibitors with potential application in the treatment of Chagas' disease
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A series of compounds bearing tetrahydronaphthalene, benzophenone, propiophenone, and related rigid molecular skeletons functionalized with thiosemicarbazone or unsaturated carbonyl moieties were prepared by chemical synthesis and evaluated for their ability to inhibit the enzyme cruzain. As potential treatment agents for Chagas' disease, three compounds from the group demonstrate potent inhibition of cruzain with IC50 values of 17, 24, and 80 nM, respectively.
- Siles, Rogelio,Chen, Shen-En,Zhou, Ming,Pinney, Kevin G.,Trawick, Mary Lynn
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p. 4405 - 4409
(2007/10/03)
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- Cobalt(II)-catalyzed cross-coupling of polyfunctional aryl copper reagents with aryl bromides and chlorides
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(Chemical Equation Presented) Polyfunctionalized biphenyl and heteroaromatic compounds were formed in the presence of [Co(acac)2], Bu4Nl, and 4-fluorostyrene (3) through a smooth cross-coupling reaction between organocopper reagents 1, prepared by the transmetalation of functionalized aryl magnesium halides with CuCN·2 LiCl, and aryl halides 2 that bear electron-withdrawing substituents. acac = acetylacetonate, DME = 1,2-dimethoxyethane, DMPU = 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone.
- Korn, Tobias J.,Knochel, Paul
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p. 2947 - 2951
(2007/10/03)
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- Generation of bromophenyllithium reagents from dibromobenzenes and addition to carbonyl and nitrile electrophiles
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An evaluation of the mono-lithiation of all three regioisomers of dibromobenzene using n-butylithium was performed. The resulting aryllithium reagents were added to electrophiles such as ketones, aldehydes, nitriles and amides to afford the desired benzylic alcohols or ketones.
- Caron, Stéphane,Do, Nga M.
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p. 1440 - 1442
(2007/10/03)
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- Synthesis of Diaryl Ketones Catalyzed by Al2O 3-ZrO2/S2O82- Solid Superacid
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The acylation of a variety of aromatic compounds with benzoyl chloride or its derivatives and catalytic amounts of Al2O3-ZrO 2/S2O82- solid superacid affords the corresponding diaryl ketones in good to excellent yields 75-93% at appropriate temperature.
- Jin, Tong-Shou,Yang, Mi-Na,Feng, Guo-Liang,Li, Tong-Shuang
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p. 479 - 485
(2007/10/03)
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- Infrared and Nuclear Magnetic Resonance Properties of Benzoyl Derivatives of Five-membered Monoheterocycles and Determination of Aromaticity Indices
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Benzophenones, 2-benzoylthiophenes, 2-benzoylpyrroles, and 2-benzoylfurans, which have substituents at m- and p-positions of the benzoyl ring were prepared and their ir and nmr spectra were obtained in 0.1 M chloroform-d solution. The chemical shift values of each series were plotted against the Hammett substituent parameters to give good correlation, with the exception of the ortho-Hs and -Cs. The slopes as well as the differences in chemical shift gave sets of meaningful values for the indices of aromaticy.
- Jeon, Kyu Ok,Jun, Jung Ho,Yu, Ji Sook,Lee, Chang Kiu
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p. 763 - 771
(2007/10/03)
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- Enantioselective oxidation of diaryl carbinols by Nocardia corallina B-276
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Whole cells of Nocardia corallina B-276 oxidized diaryl carbinols enantioselectively to give ketones in moderate yields, and some of the unreacted alcohols showed high ee's. This asymmetric oxidation is a simple and efficient method for preparing meta- and para-monosubstituted optically active diaryl carbinols from the racemates. The para-substituted chiral alcohols have an R configuration. (C) 2000 Elsevier Science Ltd.
- Perez, Herminia I.,Luna, Hector,Manjarrez, Norberto,Solis, Aida,Nuez
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p. 4263 - 4268
(2007/10/03)
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- Benzoylation of arenes using envirocat EPZG catalyst and microwave irradiation
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Benzoylations of several benzene, naphthalene and thiophene derivatives with benzoyl chloride or benzoie anhydride, catalyzed with EPZG catalyst and in the absence of solvents were studied under microwave irradiation (MWI). Reasonable to good yields of products were achieved in short times.
- Veverkova, Eva,Goyov, Battsengel,Mitterpach, Robert,Toma, Stefan
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p. 644 - 650
(2007/10/03)
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- Studies on anti-inflammatory drugs of 2-arylpropanoic acids: Part IX - A practical synthesis of ketoprofen by 1,2-aryl rearrangement
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An efficient synthesis of ketoprofen via chloration, Friedel-Crafts acylation, reduction, coupling, ketalization, rearrangement, hydrolysis and oxidation from commercially available m-bromo-benzoic acid in overall yield of about 60% has been described.
- Chen, Fener,Liu, Jidong,Shao, Lanying,Yan, Qiongjiao
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p. 989 - 992
(2007/10/03)
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- Photoinduced radical cleavage of bromophenyl ketones
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Several bromophenyl alkyl ketones undergo photoinduced radical cleavage of bromine atoms; the resulting acylphenyl radicals are trapped as the dehalogenated ketones either by alkane solvents or by added thiols. Quantum yields for this process decrease with increasing solvent viscosity; this behavior indicates that recoupling of the phenyl/ bromine radical pairs competes with their diffusion apart. In some cases Norrish type II elimination competes with the cleavage reaction. Steady state studies indicate room temperature rate constants for triplet state C-Br radical cleavage of 2 and 1 × 108 s-1, respectively, for m- and p-bromoacetophenone. Flash kinetics measurements of the temperature dependence for their triplet decay provided activation parameters for triplet state cleavage: ΔS? = -5 eu for the para isomer and -3 eu for the meta; ΔH? = 5.3 kcal/mol for both. The values for the meta isomer are the same in methanol and toluene and extrapolate to the room temperature decay rate measured by steady state techniques. The 0.002-0.003 quantum yields for conversion of m- and p-bromobenzophenone to benzophenone in cyclopentane solvent indicate triplet state cleavage rates of 0.8-1.0 × 105 s-1, which would suggest ΔH? values near 10 kcal/mol. Consideration of triplet excitation energies and of the phenyl-Br bond strength suggests a mechanism for triplet cleavage involving activated C-Br bond stretching in the triplets until a π,π* configuration is converted into a dissociative nπBr,σ* state. It is suggested that the different isomers have comparable mixing of nπBr,π* character into their π,π* triplets and that the state interconversions occur inefficiently at surface crossings with a nπBr,σ* state. The o-bromo ketones show unusual behavior. The Arrhenius plot for triplet decay of o-bromoacetophenone is curved and only half the total cleavage can be quenched by naphthalene. o-Bromobenzophenone is 500 times more reactive than its isomers; direct interaction between bromine and carbonyl as well as steric depression of the C-Br dissociation energy may both contribute to this unusual reactivity.
- Wagner, Peter J.,Sedon, James H.,Gudmundsdottir, Anna
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p. 746 - 754
(2007/10/03)
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- Photochemical Rearrangement of α-Chloro-Propiophenones to α-Arylpropanoic Acids: Studies on Chirality Transfer and Synthesis of (S)-(+)-Ibuprofen and (S)-(+)-Ketoprofen
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A new single-step efficient photochemical approach for α-arylpropanoic acids (4) from α-chloro-propiophenones (5) is described.It involves carbonyl triplet excited state directed 1,2-aryl migration of the aryl group which has been found to be highly dependent upon the nature of the aryl substituent.The mode of the rearrangement is probed by the study of the photobehaviour of a set of optically active α-chloro-propiophenones.The results suggest that the nature of the carbonyl triplets (n, ?*/ ?, ?*) plays an important role in the chirality transfer.This method finds application in the synthesis of optically active ibuprofen (4e) and ketoprofen (26), though in moderate optical yields.
- Sonawane, Harikisan,Bellur, Nanjundiah S.,Kulkarni, Dilip G.,Ayyangar, Nagaraj R.
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p. 1243 - 1260
(2007/10/02)
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- UREA BASED LIPOXYGENASE INHIBITING COMPOUNDS
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Substituted phenyl, naphthyl, and thienyl N-hydroxy urea compounds form a class of potent inhibitors of 5-and 12-lipoxygenase and are thus useful compounds in the treatment of inflammatory disease states where leukotrienes and other products of lipoxygenase enzyme activity are implicated.
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- A NEW METHOD OF SYNTHESIS OF α-ARYLPROPIONIC ACIDS INVOLVING COPPER(I) HOMOGENEOUS CATALYSIS
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The synthesis of α-arylpropionic acids involving, as first step, the facile coupling af an aryl bromide and diethyl malonate in the presence of Cu(I) bromide is described.The limits of application are discussed.
- Ugo, Renato,Nardi, Paola,Psaro, Rinaldo,Roberto, Dominique
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p. 511 - 514
(2007/10/02)
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- OXIDATIVE CYCLIZATION OF HALOBENZOPHENONE OXIMES TO 4,2'-IODONIA-3-PHENYL-1,2-BENZISOXAZOLE SALTS
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It is shown that the syn oximes of o-iodo- and o-, m-, and p-bromobenzophenones, under the influence of K2S2O8 in concentrated H2SO4, form the corresponding 3-aryl-1,2-benzisoxazoles as a result of oxidative cyclization. 3-(2-Iodophenyl)-1,2-benzisoxazole is oxidized by peracetic acid to the iodoso derivative which, upon heating in concentrated H2SO4, undergoes cyclization to the 4,2'-iodonia-3-phenyl-1,2-benzisoxazole cation.The iodide, bromide, and tetrafluoroborate of this cation were isolated.
- Tolstaya, T. P.,Egorova, L. D.,Lisichkina, I. N.
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p. 392 - 396
(2007/10/02)
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- Oxidation of Diphenylmethanol by Bromamine T. A Kinetic and Mechanistic Study
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Bromamine T (BAT) oxidises diphenylmethanol and substituted diphenylmethanols smoothly and quantitatively to the respective benzophenones in aquoeus acetic acid.Mineral acids catalyse the reaction and the rate law is found to be -d/dt=k+>.The reaction is characterised by the absence of any kinetic isotope effect and a break in the Hammett plot with ρ values of -4.2 and -0.4 for the two limbs.Three alternative mechanistic pathways have been proposed involving (i) diphenylmethyl cation, (ii) a 'phenonium ion' type intermediate from the decomposition of the alkyl hydrobromite ester, or (iii) ipso substitution at the benzene ring followed by dehydrobromination and aromatization.
- Gunasekaran, Somasundaram,Venkatasubramanian, Nagaswami
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p. 949 - 954
(2007/10/02)
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- Use of Potassium Bromate: Bromination of Derivatives of Benzene
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Bromination of various derivatives of benzene using potassium bromate under acidic condition has been discussed.
- Banerjee, Amalendu,Banerjee, Gopal Chandra,Adak, Mohini Mohan,Banerjee, Santa,Samaddar, Haraprasad
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p. 985 - 988
(2007/10/02)
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- Benzophenones and benzhydrols
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Compounds having the formula STR1 WHERE X is --CO-- or --CHOH--, Y and Z are halogen, alkyl, trifluoromethyl, alkoxy, hydroxy, nitro, cyano, carboxy, carbalkoxy, carbamoyl, or alkylthio, and m and n are 0, 1, or 2 Are useful in controlling undesirable secondary growth in plants, particularly sucker growth in tobacco.
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