- Electrochemical study of 3-(N -alkylamino)thiophenes: Experimental and theoretical insights into a unique mechanism of oxidative polymerization
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A number of conjugated polymer systems can be generated via electropolymerization, including polythiophenes and polyanilines. While both have been reported to polymerize anodically via radical coupling, the presence of the aniline nitrogen plays a significant role in the mechanism of electropolymerization. In this study, the electropolymerization mechanism of 3-(N-alkylamino)thiophenes, structural hybrids of thiophene and aniline, is studied utilizing experimental and theoretical methods. Synthesis of new short chain 3-(N-alkylamino)thiophenes is discussed, and a mechanism of electropolymerization is proposed whereby oxidation occurs through removal of a nitrogen lone pair electron, followed by a chemical step resulting in radical contribution at the 2-position of the thiophene ring. Coupling of these final radical cations thus results in a typical poly(α-α′-thiophene) backbone.
- Heth, Christopher L.,Tallman, Dennis E.,Rasmussen, Seth C.
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- Visible-light-induced Beckmann rearrangement by organic photoredox catalysis
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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
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supporting information
p. 6182 - 6186
(2020/09/01)
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- Scope and mechanism of a true organocatalytic beckmann rearrangement with a boronic acid/perfluoropinacol system under ambient conditions
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Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst and the oxime substrate.
- Mo, Xiaobin,Morgan, Timothy D. R.,Ang, Hwee Ting,Hall, Dennis G.
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supporting information
p. 5264 - 5271
(2018/04/24)
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- Efficient Heterogeneous Gold(I)-Catalyzed Direct C(sp2)–C(sp) Bond Functionalization of Arylalkynes through a Nitrogenation Process to Amides
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The first heterogeneous gold(I)-catalyzed direct C(sp2)–C(sp) bond functionalization of arylalkynes through a nitrogenation process to amides has been achieved by using an ordered mesoporous silica (MCM-41)-immobilized phosphine gold(I) complex [MCM-41-PPh3-AuCl] as catalyst and silver carbonate (Ag2CO3) as cocatalyst with trimethylsilyl azide (TMSN3) as a nitrogen source, yielding a variety of amides in moderate to excellent yields under mild conditions. This heterogeneous phosphine gold(I) complex shows the same turnover numbers as the homogeneous chloro(triphenylphosphine)gold(I) (Ph3PAuCl) and can easily be recovered by simple filtration of the reaction solution and recycled at least eight times without significant loss of activity, providing a novel, efficient, practical and economic method for the synthesis of amides from alkynes. (Figure presented.).
- Nie, Quan,Yi, Feiyan,Huang, Bin,Cai, Mingzhong
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p. 3968 - 3976
(2017/11/20)
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- Synthesis of secondary amides from N-Substituted amidines by tandem oxidative rearrangement and isocyanate elimination
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In this work an efficient tandem process transforming N-substituted amidines into secondary amides has been described. The process involves N-acylurea formation by reaction of the substrate with bis(acyloxy)(phenyl)-λ3-iodane followed by isocyanate elimination. The periodinane reagents are obtained from the commercially available phenyl-iodine(III) diacetate [PhI(OAc)2, (PIDA)] by ligand exchange with carboxylic acids. The N-substituted amidine substrates are easily synthesized from readily available nitriles. The method is applicable for secondary amide synthesis, based on both aliphatic and (hetero)aromatic amines, including challenging amides consisting of sterically hindered acids and amines. Moreover, the protocol allows one to combine steric bulk with electron deficiency in the target amides (aniline based). Such compounds are difficult to synthesize efficiently based on classical condensation reactions involving carboxylic acids and amines. Overall, the synthetic protocol transforms a nitrile into a secondary amide in both aliphatic and (hetero)aromatic systems.
- Debnath, Pradip,Baeten, Mattijs,Lefvre, Nicolas,Van Daele, Stijn,Maes, Bert U. W.
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supporting information
p. 197 - 209
(2015/03/03)
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- SPIRO-OXADIAZOLINE COMPOUNDS AS AGONISTS OF α-7-NICOTINIC ACETYLCHOLINE RECEPTORS
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The present invention relates to novel spiro-oxadiazoline compounds that are suitable as agonists or partial agonists of a7-nAChR, and pharmaceutical compositions of the same, methods of preparing these compounds and compositions, and the use of these compounds and compositions in methods of maintaining, treating and/or improving cognitive function. In particular, methods of administering a spiro-oxadiazoline cx7-nAChR agonist or partial agonist, to a patient in need thereof, for example a patient with a cognitive deficiency and/or a desire to enhance cognitive function, that may derive a benefit therefrom.
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Paragraph 00478-00479
(2015/05/19)
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- 2-[3H-THIAZOL-2-YLIDINEMETHYL]PYRIDINES AND RELATED COMPOUNDS AND THEIR USE
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The present invention pertains to certain 2-[3H-thiazol-2-ylidinemethyl]pyridine compounds and analogs thereof, which, inter alia, inhibit cell proliferation, treat cancer, etc., and more specifically to compounds of the following formula, wherein RA1, RA2, RA3, RA4, RB1, RB2, RNA, RNB, and X? are as defined herein: The present invention also pertains to pharmaceutical compositions comprising such compounds, and the use of such compounds and compositions, both in vitro and in vivo, to inhibit cell proliferation, and in the treatment of proliferative conditions such as cancer, etc.
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Page/Page column 44
(2009/10/06)
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- Facile synthesis of substituted thiophenes via Pd/C-mediated sonogashira coupling in water
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The first successful Pd/C-mediated Sonogashira coupling of iodothiophene with terminal alkynes in water is described here. Pd/C-CuI-PPh3 was found to be an efficient catalyst system for this coupling reaction. Using this economic and reliable process a variety of acetylenic thiophenes with a wide range of functional groups were prepared in good yields. Synthetic applications and in vitro anticancer properties of some of the compounds synthesized are described.
- Raju, Sirisilla,Kumar, P. Rajender,Mukkanti,Annamalai, Pazhanimuthu,Pal, Manojit
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p. 6185 - 6189
(2012/05/07)
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- DIARYL 5,6-FUSED HETEROCYCLIC ACIDS AS LEUKOTRIENE ANTAGONISTS
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Compounds having the formula I: STR1 are antagonists of the actions of leukotrienes. These compounds are useful as anti-asthmatic, anti-allergic, anti-inflammatory, and cytoprotective agents. They are also useful in treating angina, cerebral spasm, glomerular nephritis, hepatitis, endotoxemia, uveitis, and allograft rejection.
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- Pyridine and related aza heterocycle derivatives as cardiovascular agents
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Novel pharmaceutical compounds and compositions having nitrogen containing ring systems which may be represented by the following structural formula: wherein R1 or R3 is a moiety of the formula: wherein R6 is selected from either hydrogen or acetyl; R7 is selected from 2, 3 or 4-pyridyl or 1-imidazolyl and Q is -(CH2)n, where n is an integer from 1 to 5 and R1 and R2, R2 and R3, R3 and R4 or R4 and R5 taken together may be -CH=CH-CH=CH-. The compounds and compositions are useful as inhibitors of thromboxane synthetase and in the treatment of hypertension and arrythmia in mammals.
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