- Atom-economy synthesis of N-substituted carbamate from urea derivative and dimethyl carbonate catalyzed by La/SiO2: Characterization and activity
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A series of silica gel immobilized lanthanum catalysts were prepared for the atom-economy synthesis of N-substituted carbamates from urea derivatives and dimethyl carbonate. The La/SiO2 catalysts with lanthanum loadings varied from 1.3 wt% to 8.5 wt% were characterized by AES, BET, XRD, TEM, FT-IR, XPS and TPD. According to the characterization, lanthanum species with particle sizes of 5-10 nm on the surface of silica gel were formed. The catalysts were all amorphous and the surface areas were 336.5-530.2 m2/g. NH3-TPD analysis showed that all samples exhibited similar acid strength with different acid amounts. FT-IR measurement indicated that the component of lanthanum species on the catalyst surface were La(OH)3, LaOOH and hydrated La2O3. Also, the peak value of the absolute amount of LaOOH was obtained with 4.3 wt% lanthanum loading. The BET surface area decreased dramatically when the lanthanum loading was above 4.3 wt%. In consideration of the results obtained from the catalytic reactions, it could be concluded that LaOOH was the possible active species and high surface area was important for the high catalytic activity.
- Guo, Xiaoguanga,Shang, Jianpenga,Li, Jiana,Wang, Liguoa,Ma, Yuboa,Shi, Feng,Deng, Youquan
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Read Online
- Green and practical synthesis of carbamates from ureas and organic carbonates
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A practical method for the synthesis of carbamates from ureas and organic carbonates was developed with 100% atom economy using La2O 3/SiO2 as catalyst without any additional solvent. The scope of the protocol is demonstrated in the synthesis of 14 carbamates with various functional groups in excellent yields (76-95%).
- Guo, Xiaoguang,Shang, Jianpeng,Li, Jian,Wang, Liguo,Ma, Yubo,Shi, Feng,Deng, Youquan
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Read Online
- Alkene Syn- And Anti-Oxyamination with Malonoyl Peroxides
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Malonoyl peroxide 6 is an effective reagent for the syn- or anti-oxyamination of alkenes. Reaction of 6 and an alkene in the presence of O-tert-butyl-N-tosylcarbamate (R3 = CO2 tBu) leads to the anti-oxyaminated product in up to 99% yield. Use of O-methyl-N-tosyl carbamate (R3 = CO2Me) as the nitrogen nucleophile followed by treatment of the product with trifluoroacetic acid leads to the syn-oxyaminated product in up to 77% yield. Mechanisms consistent with the observed selectivities are proposed.
- Curle, Jonathan M.,Perieteanu, Marina C.,Humphreys, Philip G.,Kennedy, Alan R.,Tomkinson, Nicholas C. O.
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supporting information
p. 1659 - 1664
(2020/02/13)
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- Design, Synthesis, and Biological Evaluation of Novel, Non-Brain-Penetrant, Hybrid Cannabinoid CB1R Inverse Agonist/Inducible Nitric Oxide Synthase (iNOS) Inhibitors for the Treatment of Liver Fibrosis
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We report the design, synthesis, and structure-activity relationships of novel dual-target compounds with antagonist/inverse agonist activity at cannabinoid receptor type 1 (CB1R) and inhibitory effect on inducible nitric oxide synthase (iNOS). A series of 3,4-diarylpyrazolinecarboximidamides were synthesized and evaluated in CB1 receptor (CB1R) binding assays and iNOS activity assays. The novel compounds, designed to have limited brain penetrance, elicited potent in vitro CB1R antagonist activities and iNOS inhibitory activities. Some key compounds displayed high CB1R binding affinities. Compound 7 demonstrated potent in vivo pharmacological activities such as reduction of food intake mediated by the antagonism of the CB1Rs and antifibrotic effect in the animal models of fibrosis mediated by iNOS inhibition and CB1R antagonism.
- Iyer, Malliga R.,Cinar, Resat,Katz, Alexis,Gao, Michael,Erdelyi, Katalin,Jourdan, Tony,Coffey, Nathan J.,Pacher, Pal,Kunos, George
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p. 1126 - 1141
(2017/02/19)
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- Microwave Promoted Transcarbamylation Reaction of Sulfonylcarbamates under Continuous-Flow Conditions
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Successful conditions for the transcarbamylation/transesterification reaction of sulfonylcarbamates with alcohols by microwave heating under continuous-flow conditions were developed. After optimization of the processes, two series of O-alkylsulfonylcarbamates were obtained in high yields and purities using microwave transparent borosilicate tube reactors. In order to also illustrate the usefulness of the protocol in a medicinal chemistry context, the methodology was used for the synthesis of three angiotensin II type 2 receptor ligands.
- Kumpina, Ilze,Isaksson, Rebecka,S?vmarker, Jonas,Wannberg, Johan,Larhed, Mats
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supporting information
p. 440 - 445
(2016/03/04)
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- Rapid and straightforward transesterification of sulfonyl carbamates
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A fast and convenient method for the alkoxy exchange of sulfonyl carbamates by simply heating in a chosen alkyl alcohol is described. No catalysts or additives are required. Microwave heating at 100-120 °C for 20-60 min resulted in good to excellent yields (53-93%) of alkyl (arylsulfonyl)carbamates where the alkyl part originates from the alcohol solvent. The developed protocol was applied to the synthesis of an angiotensin II type 2 receptor (AT2R) ligand.
- Isaksson, Rebecka,Kumpi?a, Ilze,Larhed, Mats,Wannberg, Johan
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supporting information
p. 1476 - 1478
(2016/03/12)
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- Sulfonyl Azides as Precursors in Ligand-Free Palladium-Catalyzed Synthesis of Sulfonyl Carbamates and Sulfonyl Ureas and Synthesis of Sulfonamides
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(Chemical Equation Presented). An efficient synthesis of sulfonyl carbamates and sulfonyl ureas from sulfonyl azides employing a palladium-catalyzed carbonylation protocol has been developed. Using a two-chamber system, sulfonyl azides, PdCl2, and CO gas, released ex situ from Mo(CO)6, were assembled to generate sulfonyl isocyanates in situ, and alcohols and aryl amines were exploited as nucleophiles to afford a broad range of sulfonyl carbamates and sulfonyl ureas. A protocol for the direct formation of substituted sulfonamides from sulfonyl azides and amines via nucleophilic substitution was also developed.
- Chow, Shiao Y.,Stevens, Marc Y.,Odell, Luke R.
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p. 2681 - 2691
(2016/04/26)
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- A catalytic, Bronsted base strategy for intermolecular allylic C-H amination
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A Bronsted base activation mode for oxidative, Pd(II)/sulfoxide- catalyzed, intermolecular C-H allylic amination is reported. N,N-diisopropylethylamine was found to promote amination of unactivated terminal olefins, forming the corresponding linear allylic amine products with high levels of stereo-, regio-, and chemoselectivity. The predictable and high selectivity of this C-H oxidation method enables latestage incorporation of nitrogen into advanced synthetic intermediates and natural products.
- Reed, Sean A.,Mazzotti, Anthony R.,White, M. Christina
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supporting information; experimental part
p. 11701 - 11706
(2009/12/08)
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- Catalytic intermolecular linear allylic C-H amination via heterobimetallic catalysis
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A novel heterobimetallic Pd(II)sulfoxide/(salen)Cr(III)Cl-catalyzed intermolecular linear allylic C-H amination (LAA) is reported. This reaction directly converts densely functionalized α-olefin substrates (1 equiv) to linear (E)-allylic carbamates with good yields and outstanding regio- and stereoselectivities (>20:1). Chiral bis-homoallylic and homoallylic oxygen, nitrogen, and carbon substituted α-olefins undergo allylic C-H amination with good yields, excellent selectivities, and no erosion in enantiomeric purity. Streamlined routes to (E)-allylic carbamates that can be further elaborated to medicinally and biologically relevant allylic amines are also demonstrated. Valuable 15N-labeled allylic amines may be generated directly from allyl moieties at late stages of synthetic routes by using the readily available 15N-(methoxycarbonyl)-p-toluenesulfonamide nucleophile. Evidence is provided that this reaction proceeds via a heterobimetallic mechanism where Pd/sulfoxide mediates allylic C-H cleavage to form a π-allylPd intermediate, and (salen)Cr(III)Cl/BQ work together to promote functionalization with the nitrogen nucleophile. Copyright
- Reed, Sean A.,White, M. Christina
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p. 3316 - 3318
(2008/10/09)
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- Sulfonylureas as dual acting agents - Synthesis and biological activity
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2-Amino-5-aryl/alkyl-1,3,4-thiadiazoles 3a-e were used as intermediates in the synthesis of some 1,3-substituted urea derivatives 5a-o to evaluate their antidiabetic activity as well as antibacterial activity. The obtained compounds exhibited marginal activity against the animal models and the selected microorganisms.
- Chavan, Ameya A.,Pai, Nandini R.
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p. 771 - 777
(2008/03/11)
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- Planar chiral cyclic amine and its derivatives: Synthesis and stereochemical behavior
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Nine-membered diallylic cyclic amines and amides have remarkably stable planar chirality. The transformation of enantiomerically enriched amides provides optically active nitrogen heterocycles containing stereogenic centers in a stereospecific fashion.
- Tomooka, Katsuhiko,Suzuki, Masaki,Shimada, Maki,Yanagitsuru, Syun-Ichi,Uehara, Kazuhiro
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p. 963 - 965
(2007/10/03)
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- Synthesis, Biological Properties, and Molecular Modeling Investigations of Novel 3,4-Diarylpyrazolines as Potent and Selective CB1 Cannabinoid Receptor Antagonists
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A series of novel 3,4-diarylpyrazolines was synthesized and evaluated in cannabinoid (hCB1 and hCB2) receptor assays. The 3,4-diarylpyrazolines elicited potent in vitro CB1 antagonistic activities and in general exhibited high CB1 vs CB2 receptor subtype selectivities. Some key representatives showed potent pharmacological in vivo activities after oral dosing in both a CB agonist-induced blood pressure model and a CB agonist-induced hypothermia model. Chiral separation of racemic 67, followed by crystallization and an X-ray diffraction study, elucidated the absolute configuration of the eutomer 80 (SLV319) at its C4 position as 4S. Bioanalytical studies revealed a high CNS-plasma ratio for the development candidate 80. Molecular modeling studies showed a relatively close three-dimensional structural overlap between 80 and the known CB1 receptor antagonist rimonabant (SR141716A). Further analysis of the X-ray diffraction data of 80 revealed the presence of an intramolecular hydrogen bond that was confirmed by computational methods. Computational models and X-ray diffraction data indicated a different intramolecular hydrogen bonding pattern in the in vivo inactive compound 6. In addition, X-ray diffraction studies of 6 revealed a tighter intermolecular packing than 80, which also may contribute to its poorer absorption in vivo. Replacement of the amidine -NH2 moiety with a -NHCH3 group proved to be the key change for gaining oral biovailability in this series of compounds leading to the identification of 80.
- Lange, Jos H. M.,Coolen, Hein K. A. C.,Van Stuivenberg, Herman H.,Dijksman, Jessica A. R.,Herremans, Arnoud H. J.,Ronken, Eric,Keizer, Hiskias G.,Tipker, Koos,McCreary, Andrew C.,Veerman, Willem,Wals, Henri C.,Stork, Bob,Verveer, Peter C.,Den Hartog, Arnold P.,De Jong, Natasja M. J.,Adolfs, Tiny J. P.,Hoogendoorn, Jan,Kruse, Chris G.
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p. 627 - 643
(2007/10/03)
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