- Metal complexes of tetra(6-tert-butyl-2,3-quinolino)porphyrazine: I. Synthesis
-
Complexes of tetra(6-tert-butyl-2,3-quinolino)porphyrazine with Cu, Co, Zn, and Ni soluble in hydrophobic liquids were synthesized for the first time by template tetramerization of derivatives of 6-tert-butylquinoline-2,3- dicarboxylic acid formed from the corresponding acid in the course of carbamide synthesis in presence of the bivalent metal ions.
- Efimova,Korzhenevskii,Koifman
-
-
Read Online
- Catalyst-free generation of acyl radicals induced by visible light in water to construct C-N bonds
-
We describe herein a catalyst-free and redox-neutral photochemical strategy for the direct generation of acyl radicals from α-diketones, and its selective conversion of nitrosoarenes to hydroxyamides or amides with AcOH or NaCl as an additive. The reaction was carried out under mild conditions in water with purple LEDs as the light source. A broad scope of substrates was demonstrated. Mechanistic experiments indicate that α-diketones cleave to give acyl radicals, with hydroxyamides being further reduced to amides.
- Ran, Maogang,He, Jiaxin,Yan, Boyu,Liu, Wenbo,Li, Yi,Fu, Yunfen,Li, Chao-Jun,Yao, Qiuli
-
supporting information
p. 1970 - 1975
(2021/03/16)
-
- Method for promoting acylation of amine or alcohol by carbon dioxide
-
The invention relates to a method for promoting acylation of amine or alcohol by carbon dioxide, which comprises the following steps of: mixing an amine compound, carboxylate or thiocarboxylate compound and a reaction solvent under the action of carbon dioxide, and reacting to obtain an amide compound, or under the action of carbon dioxide, mixing the alcohol compound, the thiocarboxylate compound and the reaction solvent [gamma]-valerolactone, and reacting to obtain the ester compound. According to the invention, under the promotion action of carbon dioxide, carboxylate or thiocarboxylate is used as an acylation reagent, and amine and alcohol are converted into amide and ester compounds in the absence of a transition metal catalyst, so that acylation reagents such as acyl chloride or anhydride with irritation and corrosivity are avoided; and the method has the advantages of simple operation, mild reaction conditions, high tolerance of substrate functional groups, strong applicability and high yield, and provides an efficient, reliable and economical preparation method for synthesis of amide and ester compounds.
- -
-
Paragraph 0033-0034
(2021/05/29)
-
- Visible-light-induced Beckmann rearrangement by organic photoredox catalysis
-
A facile and general strategy for efficient direct conversion of oximes to amides using an inexpensive organic photocatalyst and visible light is described. This radical Beckmann rearrangement can be performed under mild conditions. Various alkyl aryl ketoximes and diaryl ketoximes can be effectively converted into the corresponding amides in excellent yields.
- Tang, Li,Wang, Zhi-Lv,Wan, Hai-Lan,He, Yan-Hong,Guan, Zhi
-
supporting information
p. 6182 - 6186
(2020/09/01)
-
- An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
-
Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
- Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
-
p. 4929 - 4936
(2020/08/21)
-
- Quantification of cooperativity in the self-assembly of H-bonded rosettes
-
The self-assembly of triaminopyrimidines with barbiturates and with cyanates was investigated in chloroform solution. Equimolar mixtures of two complementary components form stable macrocyclic 3:3 complexes (rosettes). The thermodynamics of self-assembly were quantified by using 1H NMR titrations to measure the strength of pairwise H-bonding interactions between two rosette components (K), allosteric cooperativity associated with formation of a second H-bonding interaction with each component, and the effective molarity for cyclisation of the rosette motif (EM). Pyrimidine-cyanurate interactions are an order of magnitude more favourable than pyrimidine-barbiturate interactions, so the cyanurate rosettes are significantly more stable than barbiturate rosettes. There is no allosteric cooperativity associated with rosette formation, but the chelate cooperativity quantified by the product K EM is exceptionally high (102-104), indicating that there are no other species present that compete with rosette assembly. The values of EM for rosette formation are approximately 2 M for all four rosettes studied and are not affected by differences in peripheral substituents or intrinsic H-bond strength.
- Motloch, Petr,Hunter, Christopher A.
-
supporting information
p. 1602 - 1606
(2020/03/06)
-
- Electrochemical formation of: N, N ′-diarylhydrazines by dehydrogenative N-N homocoupling reaction
-
Hydrazines represent a class of compounds of high interest due to their applicability as versatile starting materials in many important transformations. Herein, we report a synthetic approach to hydrazine derivatives using commercially available anilines and an anodic dehydrogenative N-N coupling reaction as the key step.
- Breising, Valentina M.,Kayser, Jacob M.,Kehl, Anton,Schollmeyer, Dieter,Liermann, Johannes C.,Waldvogel, Siegfried R.
-
supporting information
p. 4348 - 4351
(2020/04/27)
-
- Catalyst-free, direct electrochemical synthesis of annulated medium-sized lactams through C-C bond cleavage
-
A catalyst-free, direct electrochemical synthesis of synthetically challenging medium-sized lactams through C-C bond cleavage has been developed. In contrast to previous typical amidyl radical cyclization, this electrosynthetic approach enabled step-economical ring expansion through a unique remote amidyl migration under mild, metal- and external-oxidant-free conditions in a simple undivided cell. The strategy features unparalleled broad substrate scope with all ring sizes of (hetero)aryl-fused 8-11-membered rings and hetero atom-tethered rings, high yields, and good functional group tolerance. Our experimental and computational findings provided strong support for a SET-based reaction manifold.
- Ackermann, Lutz,Huang, Zhixing,Kuniyil, Rositha,Li, Yueheng,Ruan, Zhixiong,Xu, Zhongnan,Zhang, Chao
-
supporting information
p. 1099 - 1104
(2020/03/11)
-
- Transition-Metal-Free C-C, C-O, and C-N Cross-Couplings Enabled by Light
-
Transition-metal-catalyzed cross-couplings to construct C-C, C-O, and C-N bonds have revolutionized chemical science. Despite great achievements, these metal catalysts also raise certain issues including their high cost, requirement of specialized ligands, sensitivity to air and moisture, and so-called "transition-metal-residue issue". Complementary strategy, which does not rely on the well-established oxidative addition, transmetalation, and reductive elimination mechanistic paradigm, would potentially eliminate all of these metal-related issues. Herein, we show that aryl triflates can be coupled with potassium aryl trifluoroborates, aliphatic alcohols, and nitriles without the assistance of metal catalysts empowered by photoenergy. Control experiments reveal that among all common aryl electrophiles only aryl triflates are competent in these couplings whereas aryl iodides and bromides cannot serve as the coupling partners. DFT calculation reveals that once converted to the aryl radical cation, aryl triflate would be more favorable to ipso substitution. Fluorescence spectroscopy and cyclic voltammetry investigations suggest that the interaction between excited acetone and aryl triflate is essential to these couplings. The results in this report are anticipated to provide new opportunities to perform cross-couplings.
- Liu, Wenbo,Li, Jianbin,Querard, Pierre,Li, Chao-Jun
-
p. 6755 - 6764
(2019/05/06)
-
- Synthesis of acetamides from aryl amines and acetonitrile by diazotization under metal-free conditions
-
An efficient and metal-free coupling reaction has been developed that affords acetamides from the corresponding aryl amines and acetonitrile. This method tolerates a wide range of functional groups and is selective toward aryl amines. Preliminary mechanistic studies were conducted.
- Duan, Pan,Guo, Yu,Kang, Huan,Li, Yi-Na,Wen, Xianghao,Xiao, Fang,Zeng, Yao-Fu,Zhang, Na-Na
-
supporting information
p. 2169 - 2172
(2019/11/25)
-
- Amide Synthesis from Thiocarboxylic Acids and Amines by Spontaneous Reaction and Electrosynthesis
-
Amide bond formation is one of the most important basic reactions in chemistry. A catalyst-free approach for constructing amide bonds from thiocarboxylic acids and amines was developed. The mechanistic studies showed that the disulfide was the key intermediate for this amide synthesis. Thiobenzoic acids could be automatically oxidized to disulfides in air, thioaliphatic acids could be electro-oxidized to disulfides, and the resulting disulfides reacted with amines to give the corresponding amides. By this method, various amides could be easily synthesized in excellent yields without using any catalyst or activator. The successful synthesis of bioactive compounds also highlights the synthetic utility of this strategy in medicinal chemistry.
- Tang, Li,Matuska, Jack H.,Huang, Yu-Han,He, Yan-Hong,Guan, Zhi
-
p. 2570 - 2575
(2019/06/13)
-
- Mo-Based Oxidizers as Powerful Tools for the Synthesis of Thia- and Selenaheterocycles
-
A highly efficient synthetic protocol for the synthesis of thia- and selenaheterocycles has been developed. By employing a MoCl5-mediated intramolecular dehydrogenative coupling reaction, a broad variety of structural motifs was isolated in yields up to 94 %. The electrophilic key transformation is tolerated by several labile moieties like halides and tertiary alkyl groups. Due to the use of disulfide or diselenide precursors, a high atom efficiency was achieved.
- Franzmann, Peter,Beil, Sebastian B.,Schollmeyer, Dieter,Waldvogel, Siegfried R.
-
supporting information
p. 1936 - 1940
(2019/01/14)
-
- Synthesis and Fungicidal Activities of 2,3-Dimethyl-4-(1-acyloxy)alkoxy-6-tert-butyl-8-fluoroquinolines
-
A series of 2,3-dimethyl-4-(1-acyloxy)alkoxy-6-tert-butyl-8-fluoroquinolines were synthesized by 4-(tert-butyl)aniline as the starting material via acylation, substitution, and hydrolysis, and their structures were characterized by 1H NMR, sup
- Pei, Dan,Zhang, Fan,Liu, Jie,Zhang, Dong-Lin,Yang, Ren,Zhong, Liang-Kun,Tan, Cheng-Xia,Xu, Tian-Ming
-
p. 1383 - 1387
(2019/03/07)
-
- A carbonic acid benzyl quinoline base ester compound, preparation method and application thereof
-
The invention discloses a carbonic acid benzyl quinolyl ester compound and a preparation method thereof. The compound has the following general formula A-1, wherein the substituents are as defined in the specifications. The invention also provides applica
- -
-
Paragraph 0062-0064
(2019/02/26)
-
- Selective Oxidative Coupling Reaction of Isocyanides Using Peroxide as Switchable Alkylating and Alkoxylating Reagent
-
A switchable oxidative coupling reaction of isocyanide and peroxide has been disclosed. In the presence of iron catalyst, the coupling reaction affords N-arylacetamides in good yields. By simply replacing the iron with copper catalyst, another different coupling reaction takes place in which peroxide can serve as alkoxylating source. This protocol represents a new fundamental coupling of two basic chemicals involving C?C and C?O bond-forming process. The unusual reactivity of an isocyano group in a radical reaction acting formally as an amidoyl synthon has also been well established. The experiment outcome reveals that aromatic isocyanides are particularly compatible reaction partners in present coupling reaction, whereas no desired products are observed when aliphatic isocyanides are used. (Figure presented.).
- Zhang, Xinglu,Liu, Zhiqiang,Gao, Yu,Li, Feng,Tian, Yaming,Li, Chunju,Jia, Xueshun,Li, Jian
-
supporting information
p. 272 - 277
(2017/11/13)
-
- Regioselective nitration of anilines with Fe(NO3)3·9H2O as a promoter and a nitro source
-
An efficient Fe(NO3)3·9H2O promoted ortho-nitration reaction of aniline derivatives has been developed. This reaction may go through a nitrogen dioxide radical (NO2) intermediate, which is generated by the thermal decomposition of iron(iii) nitrate. The practicality of the present method using nontoxic and inexpensive iron reagents has been shown by the broad substrate scope and applications.
- Gao, Yang,Mao, Yuanyou,Zhang, Biwei,Zhan, Yingying,Huo, Yanping
-
supporting information
p. 3881 - 3884
(2018/06/08)
-
- Wavelength Selective Generation of Aryl Radicals and Aryl Cations for Metal-Free Photoarylations
-
Photochemical reactions have become an important tool for organic chemists. Visible (solar) light can be conveniently adopted, however, only when using colored organic compounds or in photocatalyzed processes induced by visible light absorbing photocatalysts. Herein we demonstrate that a photolabile, colored moiety could be incorporated in a colorless organic compound with the aim of generating highly reactive intermediates upon exposure to visible (solar) light. Arylazo sulfones, colored thermally stable derivatives of aryl diazonium salts, were used as valuable substrates for the photoinduced metal-free synthesis of (hetero)biaryls with no need of a (photo)catalyst or of other additives to promote the reaction. Noteworthy, selective generation of aryl radicals and aryl cations can be attained at will by varying the irradiation conditions (visible light for the former and UVA light for the latter).
- Crespi, Stefano,Protti, Stefano,Fagnoni, Maurizio
-
p. 9612 - 9619
(2016/11/02)
-
- AIBN-promoted amidation of anilines with 1, 3-diketones via oxidative cleavage of C–C bond under aerobic conditions
-
N-Acylation of anilines with 1, 3-diketones promoted by AIBN (2-2′-azoisobutyronitrile) under metal-free and peroxide-free conditions in the presence of molecular oxygen as oxidant has been described. This protocol proceeds by the oxidative cleavage of C–C bond with simultaneous intermolecular C–N bond formation under mild conditions.
- Rao, Sadu Nageswara,Mohan, Darapaneni Chandra,Adimurthy, Subbarayappa
-
p. 4889 - 4894
(2016/07/18)
-
- A mild and practical procedure for synthesis of substituted 2-aminobenzophenones
-
Abstract A convenient three-step procedure has been developed for synthesis of substituted 2-aminobenzophenones from substituted anilines. The anilines are first protected as acetanilides, by reaction with acetic anhydride. These are then benzoylated with (trichloromethyl)benzene in the presence of aluminium-generated 2-acetamidobenzophenone. Finally, removal of the acetyl group from the amino group provides the substituted 2-aminobenzophenones in moderate to good yields.
- Ma, Er-Qian,Wang, Ping,Li, Pei-He,Mo, Li-Ping
-
p. 6433 - 6441
(2015/08/18)
-
- Dioxygen reactivity of biomimetic Fe(II) complexes with noninnocent catecholate, o-aminophenolate, and o-phenylenediamine ligands
-
This study describes the O2 reactivity of a series of high-spin mononuclear Fe(II) complexes each containing the facially coordinating tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP) ligand and one of the following bidenta
- Bittner, Michael M.,Lindeman, Sergey V.,Popescu, Codrina V.,Fiedler, Adam T.
-
p. 4047 - 4061
(2014/05/06)
-
- Selective Csp2-Csp bond cleavage: The nitrogenation of alkynes to amides
-
Breakthrough: A novel catalyzed direct highly selective C sp 2-C sp bond functionalization of alkynes to amides has been developed. Nitrogenation is achieved by the highly selective C sp 2-Csp bond cleavage of aryl-substituted alkynes. The oxidant-free and mild conditions and wide substrate scope make this method very practical. Copyright
- Qin, Chong,Feng, Peng,Ou, Yang,Shen, Tao,Wang, Teng,Jiao, Ning
-
supporting information
p. 7850 - 7854
(2013/08/23)
-
- Metal-free arylations via photochemical activation of the Ar-OSO 2R bond in aryl nonaflates
-
The photolysis of electron-rich aryl nonaflates (ArONfs) in protic media was investigated and heterolysis of the Ar-OS bond (from 3ArONf) took place. The reaction generated a triplet phenyl cation that added to π-bond nucleophiles. This metal-free arylation method was made further useful by adopting in situ preparation of ArONf from the corresponding phenol.
- Raviola, Carlotta,Canevari, Veronica,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
-
supporting information
p. 2704 - 2708
(2013/10/08)
-
- BENZIIMIDAZOLE AND IMIDAZOPYRIDINE DERIVATIVES AS SODIUM CHANNEL MODULATORS
-
The invention relates to benzimidazole and imidazopyridine derivatives, to their use in medicine, to compositions containing them, to processes for their preparation and to intermediates used in such processes. More particularly the invention relates to new Nav1.8 modulators of formula (I) or pharmaceutically acceptable salts thereof, wherein R1, R2, R3, R4, R5, R6, R7. X and Y are as defined in the description. Nav1.8 modulators are potentially useful in the treatment of a wide range of disorders, particularly pain.
- -
-
Page/Page column 182
(2013/08/15)
-
- Exploitation of a Candida antarctica lipase B-catalysed in situ carboxylic acid activation method for the synthesis of acetanilides
-
An efficient biocatalytic method has been developed which provides acetanilides in good yields which are otherwise inaccessible using Candida antarctica lipase B. The process exploits the enzyme-catalysed synthesis of an acyl donor and its in situ reaction with anilines. The method is potentially useful for the synthesis of bulky acetanilides since amide formation occurs through an active site-independent step.
- Lal, Samridhi,Snape, Timothy J.
-
-
- N -acyl DBN tetraphenylborate salts as N -acylating agents
-
Air-stable and crystalline N-acyl DBN tetraphenylborate salts have been synthesized from 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and the corresponding acyl chloride in the presence of sodium tetraphenylborate. The salts have been shown to be effective N-acylating agents, reacting with primary amines, secondary amines, and sulfonamides to form the corresponding N-acylated products in good yields. The DBN hydrotetraphenylborate byproduct can be conveniently removed by filtration, providing pure N-acylated products without the need for further purification. The N-acyl DBN tetraphenylborate salts are attractive alternatives to acyl halides as they can be stored in air without decomposition, avoid the production of free acid during acylation reactions, and can be used under more forcing thermal conditions.
- Taylor, James E.,Jones, Matthew D.,Williams, Jonathan M. J.,Bull, Steven D.
-
experimental part
p. 2808 - 2818
(2012/04/23)
-
- Molecular spur gears comprising triptycene rotators and bibenzimidazole-based stators
-
Dynamic gearing of molecular spur gears, the most common type of mechanical gear, is elucidated. Molecular design and conformational analysis show that derivatives of 4,4-bis(triptycen-9-ylethynyl)bibenzimidazole represent suitable constructs to investigate gearing behavior of collateral triptycene (Tp) groups. To test this design, DFT calculations (B97-D/Def2-TZVP) were employed and the results suggest that these molecules undergo geared rotation preferentially to gear slippage. Synthesis of derivatives was carried out, providing a series of molecular spur gears, including the first desymmetrized spur gear molecules, which were subsequently subjected to stereochemical analysis.
- Frantz, Derik K.,Linden, Anthony,Baldridge, Kim K.,Siegel, Jay S.
-
supporting information; experimental part
p. 1528 - 1535
(2012/03/10)
-
- Ipso-amidation of arylboronic acids: Xenon difluoride-nitriles as efficient reagent systems
-
The xenon difluoride-mediated, ipso-amidation of boronic acids has been achieved for the first time under mild conditions. This method provides a simple, one-pot procedure for the direct synthesis of a series of anilides from the corresponding arylboronic
- Prakash, G.K. Surya,Moran, Matthew D.,Mathew, Thomas,Olah, George A.
-
experimental part
p. 806 - 809
(2010/02/28)
-
- Synthesis and property studies of cyclotrisazobenzenes
-
Azobenzenophanes are fascinating macrocycles, which are of special interest due to their unique photochromic behavior. Cyclotrisazobenzenes 2 (R = H, Br, tBu) were prepared to probe how much strain the photoisomerization of the azobenzene motive can tolerate. The macrocycles were synthesized in an overall yield of 10-20% from oriho-phenylenediamine (6). Solid-state structures of cyclotrisazobenzenes 2a and 2b were obtained. Irradiation under various conditions did not induce any isomerization.
- Reuter, Raphael,Hostettler, Nik,Neuburger, Markus,Wegner, Hermann A.
-
supporting information; experimental part
p. 5647 - 5652
(2010/02/28)
-
- Visible and near-infrared chemosensor for colorimetric and ratiometric detection of cyanide
-
A chemosensor system has been developed for rapid and selective detection of cyanide. The sensory molecules have the donor-acceptor type of structure and are designed by tuning the LUMO level or their reactivity towards cyanide. This sensory system is able to selectively distinguish cyanide among fluoride and many other anions at micromolar concentrations and instantly detect cyanide at ambient temperatures with a detection limit down to 1.0 M. Multiple sensory signals are available and can be used for both qualitative monitoring and quantitative determination of cyanide, including high-contrast visual color change, fluorescence quenching and enhancement in the visible and near-infrared spectral regions. The Royal Society of Chemistry 2009.
- Qian, Gang,Li, Xianzhen,Wang, Zhi Yuan
-
experimental part
p. 522 - 530
(2010/03/24)
-
- Pd-catalyzed amidations of aryl chlorides using monodentate biaryl phosphine ligands: A kinetic, computational, and synthetic investigation
-
We present results on the amidation of aryl halides and sulfonates utilizing a monodentate biaryl phosphine-Pd catalyst. Our results are in accord with a previous report that suggests that the formation of κ2- amidate complexes is deleterious to the effectiveness of a catalyst for this transformation and that their formation can be prevented by the use of appropriate bidentate ligands. We now provide data that suggest that the use of certain monodentate ligands can also prevent the formation of the κ2-amidate complexes and thereby generate more stable catalysts for the amination of aryl chlorides. Furthermore, computational studies shed light on the importance of the key feature(s) of the biaryl phosphines (a methyl group ortho to the phosphorus center) that enable the coupling to occur. The use of ligands that possess a methyl group ortho to the phosphorus center allows a variety of aryl and heteroaryl chlorides with various amides to be coupled in high yield.
- Ikawa, Takashi,Barder, Timothy E.,Biscoe, Mark R.,Buchwald, Stephen L.
-
p. 13001 - 13007
(2008/09/17)
-
- Quinoline synthesis: Scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes
-
Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. para-Substituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b] quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta[b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo- and thieno-[2,3e]pyridines respectively. Sequential E- to Z-benzylidene group isomerisation and six π-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone O-allyloxime, singlet excited states are involved in both steps. The Royal Society of Chemistry 2007.
- Austin, Mark,Egan, Oliver J.,Tully, Raymond,Pratt, Albert C.
-
p. 3778 - 3786
(2008/10/09)
-
- (Sensitized) photolysis of diazonium salts as a mild general method for the generation of aryl cations. Chemoselectivity of the singlet and triplet 4-substituted phenyl cations
-
(Chemical Equation Presented) The photolysis of a series of 4-X-benzenediazonium tetrafluoroborates is studied in MeCN. Loss of nitrogen occurs from the singlet excited state with X = H, t-Bu, and NMe2 and leads to the singlet aryl cation. This adds to the solvent yielding the corresponding acetanilides. With other substituents, ISC competes with (X = Br, CN) or overcomes (X = COMe, NO2) fragmentation and the aryl cation is formed in part or completely in the triplet state. In neat MeCN, this either abstracts hydrogen from the solvent (in most cases inefficiently) or undergoes intersystem crossing to the more stable singlet that reacts as above. In the presence of π nucleophiles (allyltrimethylsilane or benzene), the triplet aryl cation is efficiently trapped giving substituted allylbenzenes and biphenyls, respectively. By triplet sensitization by xanthone, the triplet cation and the products from it are obtained from the whole series considered. The direct or sensitized photodecomposition of diazonium fluoroborates, substituted with both electron-donating and -withdrawing substituents, in the presence of alkenes and arenes offers an access to an alternative arylation procedure.
- Milanesi, Silvia,Fagnoni, Maurizio,Albini, Angeld
-
p. 603 - 610
(2007/10/03)
-
- Cationic arylation through photo(sensitised) decomposition of diazonium salts. Chemoselectivity of triplet phenyl cations
-
The photodediazoniation of some 4-X-phenyldiazonium tetrafluoborates in MeCN leads to the singlet phenyl cations (X = H, tert-butyl, NMe2, CN), which add to the solvent yielding the corresponding acetanilides. Triplet sensitisation, however, leads to the triplet phenyl cation, which is reduced in neat solvent and is trapped by π nucleophiles (allyltrimethylsilane and benzene), resulting in an ionic analogue of the Meerwein or Gomberg arylations. With the 4-nitro derivative intersystem crossing prevails over dediazoniation from the singlet and with the 4-cyano competes with it, so that in those cases the triplet phenyl cation is formed also upon direct irradiation.
- Milanesi, Silvia,Fagnoni, Maurizio,Albini, Angelo
-
p. 216 - 217
(2007/10/03)
-
- Expanding Pd-catalyzed C-N bond-forming processes: The first amidation of aryl sulfonates, aqueous amination, and complementarity with Cu-catalyzed reactions
-
The first general method for the Pd-catalyzed amination of aryl tosylates and benzenesulfonates was developed utilizing ligand 1, which belongs to a new generation of biaryl monophosphine ligands. In addition, the new catalyst system for the first time enables amidation of aryl arenesulfonates and aqueous amination protocols that do not necessitate the use of cosolvents. The substrate scope has been significantly expanded to include aryl halides containing primary amides and free carboxylic acid groups. In the case of multifunctional substrates, the Pd-catalyzed amination can provide selectivity that is complementary to the Cu-catalyzed C-N bond-forming processes. Copyright
- Huang, Xiaohua,Anderson, Kevin W.,Zim, Danilo,Jiang, Lei,Klapars, Artis,Buchwald, Stephen L.
-
p. 6653 - 6655
(2007/10/03)
-
- Synthesis of butadiyne-bridged [4n] metacyclophanes having exo-annular t-butyl groups
-
Butadiyne-bridged [44]- and [48]metacyclophanes having exo-annular t-butyl groups were prepared by intermolecular Eglinton coupling of the dimeric unit or by intramolecular ring closure of the linear tetramer. Comparison of the 1H and 13C NMR spectra of [44]metacyclophane with those of [48]cyclophane and diphenylbutadiyne revealed its prominent geometrical feature due to deformation of the triple bonds from linearity. The [44]Metacyclophane was converted into [08]thiophenometacyclophane in good yield by treatment with sodium sulfide.
- Tobe, Yoshito,Utsumi, Naoto,Nagano, Atsushi,Sonoda, Motohiro,Naemura, Koichiro
-
p. 8075 - 8083
(2007/10/03)
-
- Palladium-catalyzed intermolecular coupling of aryl halides and amides
-
The first general intermolecular C-N bond-forming reactions between aryl halides and amides were realized using a palladium catalyst with Xantphos as the ligand. Aryl triflates, carbamates, and sulfonamides are also viable substrates for the amidations, which proceed at 45-110 °C with 1-4 mol% of Pd catalyst in 66-99% yields and exhibit good functional group compatibility.
- Yin, Jingjun,Buchwald, Stephen L.
-
p. 1101 - 1104
(2007/10/03)
-
- One-pot synthesis of 1,2,3,4-tetrafluoroacridines from pentafluorobenzaldehyde
-
Treatment of pentafluorobenzaldehyde with a two-molar equivalence of aniline in o-dichlorobenzene at ca. 180 yields a complex mixture of products from which 1,2,3,4-tetrafluoroacridine (1a) and its 3-anilino derivative (7a) can be isolated in at least 48
- Adamson, Adrian J.,Banks, R. Eric,Fields, Roy,Tipping, Anthony E.
-
p. 530 - 555
(2007/10/03)
-
- AROMATIC ACETYLCHOLINESTERASE INHIBITORS
-
Compounds of general formula (I), stereosiomers and pharmaceutically acceptable salts thereof, wherein each of Z and Z' are independently H or F; Q is (a), CH(OH), (b); X is H, Br, Cl, F or CF3 ; Y is H, Br, Cl, F, OH, OR5, OC(O)R4, N3, CN, NO2, SO3 H, CO
- -
-
-
- Structure-activity relationship of omeprazole and analogues as Helicobacter pylori urease inhibitors
-
Helicobacter pylori urease belongs to a family of highly conserved urea- hydrolyzing enzymes. A common feature of these enzymes is the presence of two Lewis acid nickel ions and a reactive cysteine residue in the active site. The H+/K+-ATPase inhibitor omeprazole is a prodrug of a sulfenamide which covalently modifies cysteine residues on the luminal side of the H+/K+- ATPase of gastric parietal cells. Omeprazole and eight analogues were selected based on their chemical, electronic, and kinetic properties, and each was incubated with viable H. pylori in phosphate-buffered saline at pH 7.4 for 30 min, after which 100 mM urea was added and the amount of ammonia formed analyzed after a further 10 min. Inhibition between 0% and 100% at a 0.1 mM concentration was observed for the different analogues and could be expressed as a function of the pK(a)-value of the pyridine, the pK(a)-value of the benzimidazole, the overall lipophilicity, and, most importantly, the rate of sulfenamide formation, in a quantitative structure-activity relationship. The inhibition was potentiated by a lower pH (favoring the formation of the sulfenamide) but abolished in the presence of β- mercaptoethanol (a scavenger of the sulfenamide). Structural analogues incapable of yielding the sulfenamide did not inhibit ammonia production. Treatment of Helicobacter felis-infected mice with 230 μmol/kg flurofamide b.i.d. for 4 weeks, known to potently inhibit urease activity in vivo, as a means of eradicating the infection, was tested and compared with the effect of 125 μmol/kg omeprazole b.i.d. for 4 weeks. Neither treatment proved efficacious.
- Kuhler,Fryklund,Bergman,Weilitz,Lee,Larsson
-
p. 4906 - 4916
(2007/10/03)
-
- Aluminum Chloride Catalyzed Reaction of Acetanilide with Pivalyl Chloride
-
Product development was studied in the aluminum chloride catalyzed reaction of acetanilide with pivalyl chloride. 3-tert-Butylacetanilide is the major product because of its relative resistance to dealkylation by reaction-produced HCl.At long reaction times all alkylation products are converted back to acetanilide with the only survivor being 2,2-dimethyl-5-tert-butyl-7-acetamidoindanone.The crystal structure of this compound was determined.It crystallized in the space group Pnma with cell constants a = 12.571 (3) Angstroem, b = 7.302 (1) Angstroem, c = 16.910 (3) Angstroem, V = 1552.24 Angstroem3, z = 4.Refinement of the 1224 data with F2 3?(F2) resulted in discrepancy indices R1 = 0.056 and R2 = 0.074.A novel mechanism for formation of this indanone is proposed, involving nucleophilic attack by alkene on a protonated arene ring.
- Maslak, Przemyslaw,Fanwick, Phillip E.,Guthrie, Robert D.
-
p. 655 - 659
(2007/10/02)
-