- Dehydrogenative and Redox-Neutral N-Heterocyclization of Aminoalcohols Catalyzed by Manganese Pincer Complexes
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A new manganese catalyzed heterocyclization of aminoalcohols has been accomplished. A wide range of heterocycles were synthesized, including 1,2,3,4-tetrahydroquinolines, dihydroquinolinones, and 2,3,4,5-tetrahydro-1H-benzo[b]azepines. The reaction is performed under mild reaction conditions using air and moisture stable manganese catalysts. The desired heterocycles were obtained in good to excellent yields.
- Brzozowska, Aleksandra,Rueping, Magnus,Sklyaruk, Jan,Zubar, Viktoriia
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- DMSO/t-BuONa/O2-Mediated Aerobic Dehydrogenation of Saturated N-Heterocycles
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Aromatic N-heterocycles such as quinolines, isoquinolines, and indolines are synthesized via sodium tert-butoxide-promoted oxidative dehydrogenation of the saturated heterocycles in DMSO solution. This reaction proceeds under mild reaction conditions and has a good functional group tolerance. Mechanistic studies suggest a radical pathway involving hydrogen abstraction of dimsyl radicals from the N-H bond or α-C-H of the substrates and subsequent oxidation of the nitrogen or α-aminoalkyl radicals.
- Cai, Hu,Tan, Wei,Xie, Yongfa,Yang, Ruchun,Yue, Shusheng
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p. 7501 - 7509
(2020/07/07)
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- Formal Deoxygenative Hydrogenation of Lactams Using PNHP-Pincer Ruthenium Complexes under Nonacidic Conditions
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A formal deoxygenative hydrogenation of amides to amines with RuCl2(NHC)(PNHP) (NHC = 1,3-dimethylimizadol-2-ylidene, PNHP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H2 (3.0-5.0 MPa) to amines at a temperature range of 120-150 °C with 1.0-2.0 mol % of PNHP-Ru catalysts in the presence of Cs2CO3. This process consists of (1) deaminative hydrogenation of secondary amides to generate primary amines and alcohols, (2) dehydrogenative coupling of the transient amines with alcohols to generate imines, and (3) hydrogenation of imines to give the formally deoxygenated secondary amine products.
- Ogata, Osamu,Nara, Hideki,Matsumura, Kazuhiko,Kayaki, Yoshihito
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supporting information
p. 9954 - 9959
(2019/12/24)
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- Multi-Functional Oxidase Activity of CYP102A1 (P450BM3) in the Oxidation of Quinolines and Tetrahydroquinolines
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Tetrahydroquinoline, quinoline, and dihydroquinolinone are common core motifs in drug molecules. Screening of a 48-variant library of the cytochrome P450 enzyme CYP102A1 (P450BM3), followed by targeted mutagenesis based on mutation-selectivity correlations from initial hits, has enabled the hydroxylation of substituted tetrahydroquinolines, quinolines, and 3,4-dihydro-2-quinolinones at most positions around the two rings in good to high yields at synthetically relevant scales (1.5 g L?1 day?1). Other oxidase activities, such as C?C bond desaturation, aromatization, and C?C bond formation, were also observed. The enzyme variants, with mutations at the key active site residues S72, A82, F87, I263, E267, A328, and A330, provide direct and sustainable routes to oxy-functionalized derivatives of these building block molecules for synthesis and drug discovery.
- Li, Yushu,Wong, Luet L.
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supporting information
p. 9551 - 9555
(2019/08/06)
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- Enabling CO Insertion into o-Nitrostyrenes beyond Reduction for Selective Access to Indolin-2-one and Dihydroquinolin-2-one Derivatives
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The transition metal-catalyzed reductive cyclization of o-nitrostyrene in the presence of carbon monoxide (CO) has been developed to be a general synthetic route to an indole skeleton, wherein CO was used as a reductant to deoxidize nitroarene into nitrosoarene and/or nitrene with CO2 release, but the selective insertion of CO into the heterocyclic product with higher atom economy has not yet been realized. Herein, the Pd-catalyzed reduction of o-nitrostyrene by CO and its regioselective insertion were efficiently achieved to produce synthetically useful five- and six-membered benzo-fused lactams. Detailed investigations revealed that the chemoselectivity to indole or lactam was sensitive to the nature of the counteranions of Pd2+ precursors, whereas ligands significantly decided the carbonylative regioselectivity by different reaction pathways. Using PdCl2/PPh3/B(OH)3 (condition A), an olefin hydrocarboxylation was primarily initiated followed by partial reduction of the NO2 moiety and cyclization reaction to give N-hydroxyl indolin-2-one, which was further catalytically reduced by CO to afford the indolin-2-one as the final product with up to 95% yield. When the reaction was conducted under the Pd(TFA)2/BINAP/TsOH·H2O system (condition B), complete deoxygenation and carbonylation of the NO2 group occurred initially to yield the corresponding isocyanate followed by internal hydrocyclization to generate 3,4-dihydroquinolin-2-one with up to 98% yield. Importantly, the methodology could be efficiently applied in the synthesis of marketed drug Aripiprazole.
- Yang, Li,Shi, Lijun,Xing, Qi,Huang, Kuo-Wei,Xia, Chungu,Li, Fuwei
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p. 10340 - 10348
(2018/10/20)
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- Supported Gold Nanoparticles for Efficient α-Oxygenation of Secondary and Tertiary Amines into Amides
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Although the α-oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O2as the terminal oxidant have no precedent. This report describes a novel, green α-oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al2O3). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α-oxygenation utilizes O2as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by-product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α-oxygenation provides a convenient method for the synthesis of18O-labeled amides using H218O as the oxygen source.
- Jin, Xiongjie,Kataoka, Kengo,Yatabe, Takafumi,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 7212 - 7217
(2016/07/06)
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- Imidazole derivatives as accelerators for ruthenium-catalyzed hydroesterification and hydrocarbamoylation of alkenes: Extensive ligand screening and mechanistic study
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Imidazole derivatives are effective ligands for promoting the [Ru3(CO)12]-catalyzed hydroesterification of alkenes using formates. Extensive ligand screening was performed to identify 2-hydroxymethylated imidazole as the optimal ligand. Neither carbon monoxide gas nor a directing group was required, and the reaction also showed a wide substrate generality. The Ru-imidazole catalyst system also promoted intramolecular hydrocarbamoylation to afford lactams. A Ru-imidazole complex was unambiguously analyzed by X-ray crystallography, and it had a trinuclear structure derived from one [Ru3(CO)12] and two ligands. This complex was also successfully used for hydroesterification. The mechanism was examined in detail by using D- and 13C-labeled formates, indicating that the hydroesterification reaction proceeds by a decarbonylation-recarbonylation pathway. Effective imidazole assistant: [Ru3(CO)12]-catalyzed hydroesterification of alkenes by using formates is drastically accelerated by imidazole derivatives and exhibits a broad substrate scope for both alkenes and formates. The Ru-imidazole complex also catalyzes the intramolecular hydrocarbamoylation of alkenes.
- Konishi, Hideyuki,Muto, Takashi,Ueda, Tsuyoshi,Yamada, Yayoi,Yamaguchi, Miyuki,Manabe, Kei
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p. 836 - 845
(2015/03/14)
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- Regiodivergent access to five- and six-membered benzo-fused lactams: Ru-catalyzed olefin hydrocarbamoylation
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We report herein a new strategy of the Ru-catalyzed intramolecular olefin hydrocarbamoylation for the regiodivergent synthesis of five- and six-membered benzo-fused lactams starting from N-(2-alkenylphenyl)formamides. Using a combined catalyst of Ru3
- Li, Bin,Park, Yoonsu,Chang, Sukbok
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supporting information
p. 1125 - 1131
(2014/02/14)
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- Multicomponent multicatalyst reactions (MC)2R: One-pot synthesis of 3,4-dihydroquinolinones
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A Rh/Pd/Cu catalyst system led to an efficient synthesis of dihydroquinolinones in one-pot, two operations. The reaction features the first triple metal-catalyzed transformations in one reaction vessel, without any intermediate workup. The conjugate-addition/amidation/amidation reaction sequence is highly modular, divergent, and practical.
- Zhang, Lei,Sonaglia, Lorenzo,Stacey, Jason,Lautens, Mark
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p. 2128 - 2131
(2013/06/05)
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- A nitrophenyl-based prodrug type for colorectal targeting of prednisolone, budesonide and celecoxib
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Celecoxib is a COX-2 inhibitor drug that can be used to reduce the risk of colorectal adenocarcinoma. Glucocorticoids are used in the treatment of inflammatory bowel disease. A limitation to the use of both drug types is that they undergo absorption from the intestinal tract with serious side effects. The prodrug systems introduced here involve forming a nitro-substituted acylsulfonamide group in the case of celecoxib and a nitro-substituted 21-ester for the glucocorticoids. Drug release is triggered by the nitro reductase action of the colonic microflora, liberating a cyclization competent species. The release of the active parent drugs was evaluated in vitro using Clostridium perfringens and epithelial transport through Caco-2 monolayer evaluation was carried out to estimate the absorption properties of the prodrugs compared to the parental drugs.
- Marquez Ruiz, Juan F.,Kedziora, Kinga,Pigott, Maria,Keogh, Brian,Windle, Henry,Gavin, Jason,Kelleher, Dermot P.,Gilmer, John F.
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p. 1693 - 1698
(2013/04/10)
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- Azo-reductase activated budesodine prodrugs for colon targeting
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Budesodine is a synthetic glurocorticoid that undergoes substantial first pass metabolism, limiting systemic exposure. Its use in treatment of inflammatory bowel disease would benefit from a targeting strategy that could lead to a local topical effect, improving safety and increasing anti-inflammatory efficacy. A two-step prodrug strategy involving azoreduction/cyclization that we developed previously for prednisolone is here applied with some variations to budesonide. The budesodine prodrugs were tested using an in vitro azoreductase assay simulating human colonic microflora. The kinetics of amino steroid ester cyclization and its pH dependence was also evaluated. The stability of the prodrugs systems in simulated human duodenal and gastric fluid was evaluated to determine the likelihood of intact intestinal transit. The propionic acid derived prodrug 3 undergoes rapid activation by Clostridium perfingens and its putative reduction product cyclizes with acceptable rapidity when synthesized independently. These properties of 3 suggest that it has potential in management of ulcerative colitis.
- Marquez Ruiz, Juan F.,Kedziora, Kinga,O'Reilly, Mary,Maguire, Jacqueline,Keogh, Brian,Windle, Henry,Kelleher, Dermot P.,Gilmer, John F.
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p. 7573 - 7577
(2013/02/23)
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- The synthesis of N-heterocycles via copper/TEMPO catalysed aerobic oxidation of amino alcohols
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N-Heterocycles can be prepared using alcohol oxidation as a key synthetic step. Herein we report studies exploring the potential of Cu/TEMPO as an aerobic oxidation catalyst for the synthesis of substituted indoles and quinolines.
- Flanagan, James C. A.,Dornan, Laura M.,McLaughlin, Mark G.,McCreanor, Niall G.,Cook, Matthew J.,Muldoon, Mark J.
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supporting information; experimental part
p. 1281 - 1283
(2012/06/04)
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- An efficient one pot transfer hydrogenation and N-alkylation of quinolines with alcohols mediated by Pd/C/Zn
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A Pd/C/Zn mixture with alcohols has been revealed to be an efficient transfer hydrogenation system to quinolines. Furthermore, the metals mixture is able to activate alcohols as N-alkylating agents in a hydrogen autotransfer process. 1,2,3,4-Tetrahydroquinolines and N-alkylated tetrahydroquinolines from quinolines have been obtained with excellent yields in one step.
- Abarca, Belen,Adam, Rosa,Ballesteros, Rafael
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p. 1826 - 1833
(2012/04/23)
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- A double prodrug system for colon targeting of benzenesulfonamide COX-2 inhibitors
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The design, synthesis and delivery potential of a new type of benzenesulfonamide cyclo-oxygenase-2 (COX-2) inhibitor prodrug is investigated using celecoxib. The approach involves a double prodrug that is activated first by azoreductases and then by cyclization triggering drug release. We studied the intramolecular aminolysis of the acylsulfonamide. The cyclization was surprisingly rapid at physiological pH and very fast at pH 5. The prodrug is activated specifically under conditions found in the colon but highly stable in the presence of human and rodent intestinal extracts. Finally, the prototype with celecoxib was transported much more slowly in the Caco-2 transepithelial model than the parent. The design therefore shows significant promise for the site specific delivery of benzenesulfonamide COX-2 inhibitors to the colon.
- Marquez Ruiz, Juan F.,Kedziora, Kinga,Keogh, Brian,Maguire, Jacqueline,Reilly, Mary,Windle, Henry,Kelleher, Dermot P.,Gilmer, John F.
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scheme or table
p. 6636 - 6640
(2011/12/21)
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- Synthesis, 3D-QSAR, and structural modeling of benzolactam derivatives with binding affinity for the D2and D3 receptors
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A series of 37 benzolactam derivatives were synthesized, and their respective affinities for the dopamine D2 and D3 receptors evaluated. The relationships between structures and binding affinities were investigated using both ligand-based (3D-QSAR) and receptor-based methods. The results revealed the importance of diverse structural features in explaining the differences in the observed affinities, such as the location of the benzolactam carbonyl oxygen, or the overall length of the compounds. The optimal values for such ligand properties are slightly different for the D2 and D 3 receptors, even though the binding sites present a very high degree of homology. We explain these differences by the presence of a hydrogen bond network in the D2 receptor which is absent in the D3 receptor and limits the dimensions of the binding pocket, causing residues in helix 7 to become less accessible. The implications of these results for the design of more potent and selective benzolactam derivatives are presented and discussed.
- Lopez, Laura,Selent, Jana,Ortega, Raquel,Masaguer, Christian F.,Dominguez, Eduardo,Areias, Filipe,Brea, Jose,Loza, Maria Isabel,Sanz, Ferran,Pastor, Manuel
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experimental part
p. 1300 - 1317
(2011/01/04)
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- New synthetic methodology for construction of the 1,3,4,5-tetrahydro-2 H -1,3-benzodiazepin-2-one skeleton
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We hereby report a new synthetic methodology for construction of the 1,3,4,5-tetrahydro-2H-1,3-benzodiazepin-2-one skeleton. 2-(2-Carboxyethyl) benzoic acid was converted into the corresponding bis(acyl azide). Curtius rearrangement of the diazide followed by reaction with alcohols provided diurethane derivatives. Ring-closure reaction of the diurethanes with base resulted in formation of the 1,3-benzodiazepin-2-one skeleton. Georg Thieme Verlag Stuttgart · New York.
- Dengiz, Cagatay,Oezcan, Sevil,Sahin, Ertan,Balci, Metin
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experimental part
p. 1365 - 1370
(2010/07/02)
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- TARGETING DIAZO PRODRUGS FOR THE TREATMENT OF GASTROINTESTINAL DISEASES
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Provided herein are compounds, compositions and methods for decreasing NFkB DNA-binding activity in a patient comprising administering of a therapeutically effective amount of a compound or composition of the application to the patient to reduce, alleviate or treat various gastrointestinal diseases, such as inflammatory bowel disease (IBD).
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Page/Page column 10; 44-45; 3/11 - 5/11
(2009/03/07)
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- Design, synthesis, and pharmacological effects of a cyclization-activated steroid prodrug for colon targeting in inflammatory bowel disease
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Glucocorticoids are used in the treatment of inflammatory bowel disease. A limitation to their use is that they undergo absorption from the GIT before reaching the colon causing severe systemic side effects. We report here on a novel prodrug approach to targeting corticosteroids to the colon. The design involves attaching a 21-ester group that suppresses absorption during transit to the colon. The prodrug is designed to be primed by colonic microflora liberating an amino ester that cyclizes releasing the steroid. One of the prodrugs 5b was as efficacious as prednisolone in the murine DSS model but did not cause thymic atrophy, a marker for systemic steroid effects.
- Márquez Ruiz, Juan F.,Radics, Gabor,Windle, Henry,Serra, Hugo O.,Simplício, Ana Luísa,Kedziora, Kinga,Fallon, Padraic G.,Kelleher, Dermot P.,Gilmer, John F.
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supporting information; experimental part
p. 3205 - 3211
(2010/03/24)
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- Synthesis, binding affinity and SAR of new benzolactam derivatives as dopamine D3 receptor ligands
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A series of new benzolactam derivatives was synthesized and the derivatives were evaluated for their affinities at the dopamine D1, D2, and D3 receptors. Some of these compounds showed high D2 and/or D3/su
- Ortega, Raquel,Ravina, Enrique,Masaguer, Christian F.,Areias, Filipe,Brea, Jose,Loza, Maria I.,Lopez, Laura,Selent, Jana,Pastor, Manuel,Sanz, Ferran
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scheme or table
p. 1773 - 1778
(2009/12/03)
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- Recyclable selective palladium-catalyzed synthesis of five-, six- or seven-membered ring lactones and lactams by cyclocarbonylation in ionic liquids
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The ionic liquids, BMIM PF6 or BMIM NTf2, are used successfully for the palladium-catalyzed cyclocarbonylation of 2-allylphenols and anilines, 2-vinylphenols, and 2-aminostyrenes. The reaction proceeds cleanly and efficiently to afford high yields of lactones or lactams with good or excellent selectivity for one isomer. The ionic liquid containing the palladium catalyst, and ligand, is recyclable in all cases.
- Ye, Fangguo,Alper, Howard
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p. 1855 - 1861
(2007/10/03)
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- A new protecting group for the exocyclic amino groups of nucleosides
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A new protecting group has been developed for the exocyclic amino groups of nucleosides that occur in DNA. 3-Phenyl-[{N-(2-trimethylsilyl-ethoxycarbonyl)- 2-amino}]-propanoic acid used as the protective agent.
- Varaprasad, Chamakura V.N.S.,Johnson, Francis
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p. 2163 - 2165
(2007/10/03)
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- Reactions of 2-, 3- and 4-quinolinols with cyclohexane and benzene in superacids
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Isomeric 2-, 3- and 4-quinolinols (11-13) underwent selective ionic hydrogenation with cyclohexane in CF3SO3H-SbF5 system to give 5,6,7,8-tetrahydro-2(1H)-quinolinone, 5,6,7,8-tetrahydro-3-quinolinol and 5,6,7,8-tetrahydro-4(1H)-quinolinone (28-30), respectively. When reaction was carried out in the presence of excess of aluminum chloride, 11 gave 3,4-dihydro-2(1H)-quinolinone (31), whereas 13 gave the product (30). Compounds (11) and (13) condense with benzene in the presence of aluminum halides producing phenyl substituted derivatives of 28, 31 and 30 (products 32-34), respectively. The mechanism of these and related reactions involving superelectrophilic dicationic intermediates is discussed.
- Koltunov, Konstantin Yu.,Prakash, G. K. Surya,Rasul, Golam,Olah, George A.
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p. 757 - 772
(2007/10/03)
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- A study on the conversion of indanones into carbostyrils
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We have surveyed the utility of Beckmann rearrangement for the conversion of indanones into carbostyrils. Initial attempts at the conversion of 6-methoxy indanone oxime under classical conditions resulted in the formation of the two unusual products: 2-sulfonyloxyindanone and the dimeric product. This unusual rearrangement was also observed by the treatment of some metal triflates species. Further investigation has led to the development of reliable conditions starting from oxime mesylate (not oxime tosylate), in which some strong Lewis acid catalyst (ZrCl4) was employed in either a conventional or non-conventional solvent system. The advantage of the new protocol is highlighted by the simple work up and direct isolation of the product in 65% isolated yield.
- Torisawa, Yasuhiro,Nishi, Takao,Minamikawa, Jun-Ichi
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p. 2205 - 2209
(2007/10/03)
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- Radical ring closures of 4-isocyanato carbon-centered radicals
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The 2-(2-isocyanatophenyl)ethyl radical was generated from the corresponding bromide with tributyltin and tris(trimethylsilyl)silyl radicals and shown to ring close in the 6-endo-mode to afford 3,4-dihydro-1H-quinolin-2-one as the major product. Cyclization in the 5-exo-mode to produce 2,3-dihydroindole-1-carbaldehyde, after hydrogen abstraction, was a minor reaction. Rate constants for the two processes were estimated and compared with reaction enthalpies computed by the DFT method.
- Minin, Patricia L.,Walton, John C.
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p. 2960 - 2963
(2007/10/03)
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- Interesting reaction of the indanone oximes under Beckmann rearrangement conditions
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Attempted Beckmann rearrangement of the 6-methoxyindanone oximes in conventional conditions resulted in the formation of the two kinds of unexpected products: 2-sulfonyloxyindanone and the dimeric product. Related rearrangement was also observed in the re
- Torisawa, Yasuhiro,Nishi, Takao,Minamikawa, Jun-Ichi
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p. 387 - 390
(2007/10/03)
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- Cycloalkyl, lactam, lactone and related compounds, pharmaceutical compositions comprising same, and methods for inhibiting beta-amyloid peptide release and/or its synthesis by use of such compounds
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Disclosed are compounds which inhibit β-amyloid peptide release and/or its synthesis, and, accordingly, have utility in treating Alzheimer's disease. Also disclosed are pharmaceutical compositions comprising a compound which inhibits β-amyloid peptide release and/or its synthesis as well as methods for treating Alzheimer's disease both prophylactically and therapeutically with such pharmaceutical compositions.
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- Regioselective palladium(II)-catalyzed synthesis of five- or seven-membered ring lactones and five-, six- or seven-membered ring lactams by cyclocarbonylation methodology
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2-Allylphenols react with carbon monoxide and hydrogen in the presence of catalytic quantities of a cationic palladium(II) complex [(PCy3)2Pd(H)(H2O)]+BF4- or palladium acetate and 1,4-bis(diphenylpho
- El Ali, Bassam,Okuro, Kazumi,Vasapollo, Giuseppe,Alper, Howard
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p. 4264 - 4270
(2007/10/03)
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- Novel and facile reduction of heterocyclic compounds with lanthanoid metal-hydrochloric acid system
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Pyridines were rapidly reduced to piperidines with Sm or Yb-HCl system at room temperature in quantitative yields. Quinolines and isoquinolines were similarly reduced to the corresponding 1,2,3,4-tetrahydro-derivatives with Sm-HCl system in good yields.
- Kamochi,Kudo
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p. 1422 - 1424
(2007/10/02)
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- Heterocyclic derivatives
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Compounds of formula I STR1 wherein R2, R3, R4, R10 and R11 have any of the meanings given in the specification, and their pharmaceutically acceptable salts are useful in the treatment of urinery incontinence. Also disclosed are pharmaceutical compositions, processes for preparing the compounds of formula I and intermediates.
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- Intramolecular Reactions Using Amide Links: Aryl Radical Cyclisation of Silylated Acryloylanilides
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Aryl radical cyclisations of in situ silylated o-bromoacryloylanilides are presented and shown to lead to N-unsubstituted oxindoles and dihydroquinolones in very different ratios than those previously observed for the N-alkyl o-bromoacryloylanilides.
- Jones, Keith,Wilkinson, James,Ewin, Richard
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p. 7673 - 7676
(2007/10/02)
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- Orally active, nonpeptide vasopressin V1 antagonists. A novel series of 1-(1-substituted 4-piperidyl)-3,4-dihydro-2(1H)-quinolinone
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A series of compounds has been synthesized and demonstrated to be antagonists of V1 receptors both in vitro and in vivo. These compounds are structurally related to the 1-(4-piperidyl)-2(1H)-quinolinones, including OPC-21268, an orally bioavail
- Ogawa,Yamamura,Miyamoto,Kondo,Yamashita,Nakaya,Chihara,Mori,Tominaga,Yabuuchi
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p. 2011 - 2017
(2007/10/02)
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- Synthesis of Oxindole Derivatives from N-Alkenyl-o-Chloroanilides with Zero-Valent Nickel Complex
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Oxindole derivatives have been obtained from N-alkenyl-o-chloroanilides by reaction with tetrakis(triphenylphoaphine)nickel(0) in toluene as solvent in good yields.A detailed analysis of all the products of the reaction allows to confirm the postulated mechanism of the cyclization reaction.The o-chloroanilides of the 3-cyclohexenylacetic acid fails in the cyclization reaction, since the torsional hindrance seems to avoid that the endocyclic double bond may be orthogonally to the ortho-?-nickel complex intermediate on the aromatic ring.
- Canoira, L.,Rodriguez, J. G.
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p. 1511 - 1518
(2007/10/02)
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- INTRAMOLECULAR AMIDATION OF ARYLALKYLHYDROXAMIC ACIDS
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It is shown that mixtures of two isomeric benzolactams, viz., compounds of the benzamide and anilide type, are formed in the intramolecular amidation of arylalkylhydroxamic acids under the influence of polyphosphoric acid (PPA).A general reaction scheme that includes three pathways, viz., direct amidation, Losen rearrangement of the hydroxamic acids with subsequent cyclization of the isocyanates, and Beckmann rearrangement of the oximes of the cyclic ketones formed in the thermal cleavage of the starting hydroxamic acids in PPA, is proposed on the basis of a study of racemic and optically active arylalkylhydroxamic acids.
- Potapov, V.M.,Dem'yanovich, V. M.,Vendrova, O. E.,Khlebnikov, V. A.
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p. 528 - 533
(2007/10/02)
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