- Condensation reactions assisted by acidic hydrogen bonded hydroxyl groups in solid tin(ii)hydroxychloride
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Tin(ii)hydroxychloride is reported as a heterogeneous Bronsted acid catalyst. Sn(OH)Cl was synthesized by a precipitation method and characterized by XRD, FT-IR, 1H MAS NMR, SEM, TG-DTA and N2 sorption. The acidity measurements of tin(ii)hydroxychloride by FT-IR pyridine adsorption and 1H MAS NMR showed the presence of Bronsted acidity. The Bronsted acidity can be attributed to strong hydrogen bonding between the -OH and Cl groups. Sn(OH)Cl showed high activity for important condensation reactions such as the Prins condensation, Claisen-Schmidt condensation and ketalization. The catalytic activity of Sn(OH)Cl was compared with that of SnO, SnO2 and Sn2(OH)2O. The catalyst was recycled three times with a negligible decrease in activity. The Royal Society of Chemistry 2013.
- Marakatti, Vijaykumar S.,Shanbhag, Ganapati V.,Halgeri, Anand B.
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- Mesoporous iron phosphate as an active, selective and recyclable catalyst for the synthesis of nopol by Prins condensation.
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Mesoporous iron phosphate is found to be a highly active and recyclable heterogeneous catalyst for the selective synthesis of nopol by Prins condensation of beta-pinene and paraformaldehyde in acetonitrile at 80 degrees C.
- Pillai, Unnikrishnan R,Sahle-Demessie, Endalkachew
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- Exploring the catalytic performance of a series of bimetallic MIL-100(Fe, Ni) MOFs
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A series of mixed-metal FeIII/NiII metal-organic frameworks (MOFs) of the MIL-100 type containing different metal ratios have been synthesized de novo, following an approach that requires tuning of the FeIII/NiII reactivity. The resulting heterometallic MIL-100(Fe, Ni) materials maintain thermal, chemical and structural stability with respect to the parent MIL-100(Fe) MOF as can be deduced from various techniques. The nature and the oxidation state of the accessible metal cations have been evaluated by in situ infrared spectroscopy and extended X-ray absorption fine structure measurements. The obtained mixed-metal MOFs and the parent material have been evaluated as heterogeneous catalysts in a model acid-catalyzed reaction, i.e., the Prins reaction. It is found that the catalytic activity improves by more than one order of magnitude upon incorporation of NiII, with a complete selectivity for the formation of nopol. This increase in the catalytic activity upon incorporation of NiII correlates with the enhancement in the Lewis acidity of the material as determined by CO adsorption. The heterometallic MOF can be recycled without observation of metal leaching, while maintaining the crystal structure under the reaction conditions.
- Giménez-Marqués, Mónica,Santiago-Portillo, Andrea,Navalón, Sergio,álvaro, Mercedes,Briois, Valérie,Nouar, Farid,Garcia, Hermenegildo,Serre, Christian
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- Synthesis of zirconia porous phosphate heterostructures (Zr-PPH) for Prins condensation
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Porous phosphate heterostructure materials with zirconia galleries have been prepared. Their acid properties were studied via 2,6-di-tert-butyl-pyridine adsorption, infrared spectra of pyridine adsorption and potentiometric titration. The samples prepared in alcohol media are more thermal stable than those prepared in aqueous media. They are very active and selective for the Prins condensation of β-pinene with paraformaldehyde because of large amount of Lewis acid sites as well as proper L/B ratio. The selectivity towards Nopol can be further improved by ion-exchanging with sodium cations, due to the elimination of Br?nsted acid sites which suppresses the by-reactions such as isomerization of β-pinene.
- Wang, Xueyan,Wang, Tao,Hua, Weiming,Yue, Yinghong,Gao, Zi
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- Well ordered two-dimensional SnSBA-15 catalysts synthesized with high levels of tetrahedral tin for highly efficient and clean synthesis of nopol
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Highly ordered two-dimensional SnSBA-15 molecular sieve catalysts with different concentrations of tin species have been synthesized using Pluronic P123 as a structure directing agent under pH-adjusting direct hydrothermal method and have been used for synthesis of nopol by Prins condensation of β-pinene with paraformaldehyde. The influence of various reaction parameters on this reaction has been investigated. The Prins condensation reaction has also been carried out with different solvents for finding the best solvent with a good catalytic activity. In addition, the Prins condensation of β-pinene with paraformaldehyde in the presence of propyl cyanide with water has been carried out for the synthesis of nopol, and in this condition the catalytic activity of the catalyst used was not seriously affected. On the basis of all catalytic results, SnSBA-15(5) is found to be a highly active, water-resistant and recyclable heterogeneous catalyst for selective synthesis of nopol.
- Selvaraj,Choe
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- Synthesis, antifungal activity, and 3d-qsar study of novel nopol-derived 1,3,4-thiadiazole-thiourea compounds
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A series of novel nopol derivatives bearing the 1,3,4-thiadiazole-thiourea moiety were designed and synthesized by multi-step reactions in search of potent natural product-based antifungal agents. Their structures were confirmed by FT-IR, NMR, ESI-MS, and elemental analysis. Antifungal activity of the target compounds was preliminarily evaluated by in vitro methods against Fusarium oxysporum f. sp. cucumerinum, Cercospora arachidicola, Physalospora piricola, Alternaria solani, Gibberella zeae, Rhizoeotnia solani, Bipolaris maydis, and Colleterichum orbicalare at 50 μg/mL. All the target compounds exhibited better antifungal activity against P. piricola, C. arachidicola, and A. solani. Compound 6j (R = m, p-Cl Ph) showed the best broad-spectrum antifungal activity against all the tested fungi. Compounds 6c (R = m-Me Ph), 6q (R = i-Pr), and 6i (R = p-Cl Ph) had inhibition rates of 86.1%, 86.1%, and 80.2%, respectively, against P. piricola, much better than that of the positive control chlorothalonil. Moreover, compounds 6h (R = m-Cl Ph) and 6n (R = o-CF3 Ph) held inhibition rates of 80.6% and 79.0% against C. arachidicola and G. zeae, respectively, much better than that of the commercial fungicide chlorothalonil. In order to design more effective antifungal compounds against A. solani, analysis of the three-dimensional quantitative structure–activity relationship (3D-QSAR) was carried out using the CoMFA method, and a reasonable and effective 3D-QSAR model (r2 = 0.992, q2 = 0.753) has been established. Furthermore, some intriguing structure–activity relationships were found and are discussed by theoretical calculation.
- Chen, Ming,Duan, Wen-Gui,Fan, Zhong-Tian,Lin, Gui-Shan,Wang, Xiu
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- Synthesis, antifungal activity and 3D-QSAR study of novel nopol-based 1,3,4-thiadiazole–thioether compounds
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A series of novel nopol derivatives containing 1,3,4-thiadiazole–thioether moiety were synthesized from β-pinene, which is a natural, abundant and renewable biomass resource. Their structures were characterized by FT-IR, 1H NMR, 13C NMR, ESI–MS and elemental analysis. In vitro antifungal activity of the target compounds was preliminarily evaluated against eight tested plant pathogens, including Fusarium oxysporum f. sp. cucumerinum, Cercospora arachidicola, Physalospora piricola, Alternaria solani, Gibberella zeae, Rhizoeotnia solani, Bipolaris maydis and Colleterichum orbicalare. The bioassay results revealed that, at the concentration of 50?μg/mL, all the target compounds showed certain inhibition activity against the eight tested fungi. Compounds 5f (R = m–OCH3), 5i (R = m–F) and 5r (R = m–I) had excellent inhibition rates of 77.8%, 88.9% and 77.8%, respectively, against P. piricola, showing much better antifungal activity than that of the positive control chlorothalonil. Meanwhile, compound 5?m (R = p–Cl) displayed antifungal activity of 80.7% against R. solani. Furthermore, the analysis of three-dimensional quantitative structure–activity relationship (3D-QSAR) was performed for the relationship between the structures of the target compounds and their antifungal activity against P. piricola by CoMFA method. A reasonable CoMFA model (n = 6; q2 = 0.597; r2 = 0.985) was established.
- Wang, Xiu,Duan, Wen-Gui,Lin, Gui-Shan,Chen, Ming,Lei, Fu-Hou
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p. 4029 - 4049
(2021/06/21)
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- Design, synthesis and application of pinenyl chiral olefin and carbene ligand
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The invention discloses design, synthesis and application of pinenyl chiral olefin and carbene ligands. According to the carbene ligand, pinene or 9-anthraceneformaldehyde is taken as a chiral source,a corresponding bromide is obtained through a two-step reaction, then benzimidazole is taken as an initial raw material, reacts with one molecule of bromide and then reacts with the other molecule ofbromide to form a salt, and corresponding pinenyl chiral olefin and carbene ligands are obtained; the carbene ligand is used as a chiral catalyst to perform asymmetric 1, 4-addition reaction, and hasfavorable selectivity.
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Paragraph 0031; 0035-0037
(2020/11/10)
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- Design of stable mixed-metal MIL-101(Cr/Fe) materials with enhanced catalytic activity for the Prins reaction
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This work highlights the benefit of designing mixed-metal (Cr/Fe) MOFs for enhanced chemical stability and catalytic activity. A robust and stable mixed-metal MIL-101(Cr/Fe) was prepared through a HF-free direct hydrothermal route with Fe3+ content up to 21 wt%. The incorporation of Fe3+ cations in the crystal structure was confirmed by 57Fe M?ssbauer spectrometry. The catalytic performance of the mixed metal MIL-101(Cr/Fe) was evaluated in the Prins reaction. MIL-101(Cr/Fe) exhibited a higher catalytic activity compared to MIL-101(Cr), improved chemical stability compared to MIL-101(Fe) and a higher catalytic activity for bulky substrates compared to MIL-100(Fe). In situ infra-red spectroscopy study suggests that the incorporation of Fe3+ ions in MIL-101 structure leads to an increase in Lewis acid sites. It was thus concluded that the predominant role of Cr3+ ions was to maintain the crystal structure, while Fe3+ ions enhanced the catalytic activity.
- álvaro, Mercedes,García, Hermenegildo,Giménez-Marqués, Mónica,Gkaniatsou, Effrosyni,Greneche, Jean-Marc,Navalón, Sergio,Santiago-Portillo, Andrea,Serre, Christian,Sicard, Clémence,Steunou, Nathalie,Vallés-García, Cristina
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supporting information
p. 17002 - 17011
(2020/09/16)
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- Influence of Terephthalic Acid Substituents on the Catalytic Activity of MIL-101(Cr) in Three Lewis Acid Catalyzed Reactions
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Six isostructural MIL-101(Cr)-X (X: H, NO2, SO3H, Cl, CH3, and NH2) materials have been prepared directly by the reaction of CrIII salts and the corresponding terephthalic acid or by postsynthetic treatments of preformed MIL-101(Cr) following reported procedures. The materials were characterized by using XRD (crystallinity and coincident diffraction pattern), isothermal N2 adsorption (specific surface areas range from 2740 m2 g?1 for MIL-101(Cr)-H to 1250 m2 g?1 for MIL-101(Cr)-Cl), thermogravimetry (thermal stability up to 400 °C), and IR spectroscopy (detection of the corresponding substituents), and the results were all in agreement with the reported data for these materials. The MIL-101(Cr) materials were tested as heterogeneous catalysts for epoxide ring opening by methanol, benzaldehyde acetalization by methanol, and Prins coupling, observing a clear influence of the substituent that in general follows a linear relationship with the Hammett σmeta constant of the substituent: the catalytic activity increases as the electron-withdrawing ability of the substituents increases. An up to three orders of magnitude enhancement in the presence of the NO2 substituent was found for some of these reactions. The present study illustrates the versatility that metal–organic frameworks offer as heterogeneous catalysts that allow the design of actives sites with adequate properties tuned for each reaction.
- Santiago-Portillo, Andrea,Navalón, Sergio,Concepción, Patricia,álvaro, Mercedes,García, Hermenegildo
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p. 2506 - 2511
(2017/07/12)
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- Reductive amine deallyl- and debenzylation with alkali metal in Silica Gel (M-SG)
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Alkali metals in silica gel (the M-SG materials) are effective reagents for reductive deallylation, debenzylation, debenzhydrylation, and detritylation of amines. As such, these reagents provide a convenient alternative to traditional metal ammonia solutions for this class of deprotections.
- Nandi, Partha,Dye, James L.,Jackson, James E.
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supporting information; experimental part
p. 3864 - 3866
(2009/09/28)
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- Selective catalytic activity of ball-shaped Pd@MCM-48 nanocatalysts
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Remarkable selectivity is achieved in the cleavage of benzyl ethers using ball-shaped palladium nanocatalysts, Pd@MCM-48, in an MCM-48 matrix. The unique nanocatalysts not only feature unprecedented complete hydrogenolysis selectivity of a benzyl ether over hydrogenation of a double bond, but also demonstrate selective cleavage of unsubstituted benzyl ether over substituted benzyl ethers. The Royal Society of Chemistry 2006.
- Lee, Hee-Yoon,Ryu, Suyoung,Kang, Hongkyu,Jun, Young-Wook,Cheon, Jinwoo
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p. 1325 - 1327
(2008/02/03)
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- An efficient protocol for the preparation of MOM ethers and their deprotection using zirconium(IV) chloride
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An efficient protocol for the preparation of MOM ethers from alcohols and formaldehyde dimethyl acetal (DMFA) using ZrCl4 (10 mol %) at room temperature under solvent free conditions has been developed. Similarly, the same Lewis acid, ZrCl4 (50 mol %), in isopropanol at reflux was utilised for the deprotection of MOM ethers. An efficient protocol for the preparation of MOM ethers from alcohols and formaldehyde dimethyl acetal (DMFA) using ZrCl4 (10 mol %) at room temperature under solvent free conditions has been developed. Similarly, the same Lewis acid, ZrCl4 (50 mol %), in isopropanol at reflux was utilised for the deprotection of MOM ethers.
- Sharma,Reddy, K. Laxma,Sree Lakshmi,Radha Krishna, Palakodety
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p. 9229 - 9232
(2007/10/03)
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- p-Methoxy Diphenylmethanol (MDPM), p-Phenyl Diphenylmethanol (PDPM), and p-Phenylphenyl Diphenylmethanol (PPDPM) - Protecting Groups for Alcohols - Protection and Deprotection
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Two new protecting groups viz. p-phenyl diphenylmethanol (PDPM) and p-phenylphenyl diphenylmethanol (PPDPM) were prepared and utilized along with p-methoxy diphenylmethanol (MDPM), for the protection of alcohols in the presence of Yb(OTf)3. Deprotection of the above ethers was achieved using DDQ or CF3COOH.
- Sharma,Prasad, T. Rajendra,Srinivas, Rakesh B.
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p. 941 - 950
(2007/10/03)
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- A facile zirconium(IV) chloride catalysed selective deprotection of t-butyldimethylsilyl (TBDMS) ethers
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A simple and efficient protocol for the selective deprotection of t-butyldimethylsilyl (TBDMS) ethers using 20 mol% ZrCl4 in 20-45 min and in high yields, is reported, wherein it is demonstrated that acid and base sensitive groups and allylic and benzylic groups are unaffected.
- Sharma,Srinivas,Radha Krishna, Palakodety
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p. 4689 - 4691
(2007/10/03)
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- An efficient and chemoselective cleavage of prenyl ethers with DDQ
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The prenyl (Pre) protecting group tor hydroxyl functions is readily removed at room temperature with DDQ in dichloromethane-water (9:1). The reaction conditions are compatible with the presence of other ethereal functionalities such as acetonides, allyl, benzyl, TBS, TBDPS groups. We have also shown that Sdeprotection of prenyl ethers using a catalytic amount of DDQ in the presence of 3 equivalents of Mn(OAc)3 is a good alternative for the use of a stoichiometric amount of DDQ, albeit the reaction time being longer.
- Vatéle, Jean-Michel
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p. 507 - 509
(2007/10/03)
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- Deprotection and direct oxidative deprotection of trimethylsilyl ethers to their corresponding alcohols and carbonyl compounds with tris[trinitratocerium(IV)] paraperiodate, [(NO3)3Ce]3.H2IO6, in an aprotic solvent
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Deprotection of structurally different trimethylsilyl ethers to their corresponding alcohols has been achieved in refluxing benzene in the presence of tris[trinitratocerium(IV)] paraperiodate in a few minutes. This reagent has also been used successfully for the direct oxidation of trimethylsilyl ethers to their corresponding carbonyl compounds. Benzylic double bonds are prone to cleavage reactions with this method.
- Firouzabadi,Shiriny
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p. 423 - 432
(2007/10/03)
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- PRODUCTS FROM SOLVOLYSIS OF 2-(2-TOSYLOXYETHYL)-6,6-DIMETHYLBICYCLOHEPT-2-ENE
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The solvolysis of 2-(2-tosyloxyethyl)-6,6-dimethylbicyclohept-2-ene takes place with retention of the gem-dimethylcyclobutane ring of the substrate and is accompanied by simultaneous opening of the additional three-or four-membered ring in the reaction product.
- Vyglazov, O. G.,Urbanovich, T. R.,Manukov, E. N.,Chuiko, V. A.,Udarov, B. G.
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p. 1896 - 1900
(2007/10/02)
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- HOMOLYTIC DISPLACEMENT AT CARBON. X. TOLUENESULPHONYL IODIDE AS A SOURCE OF TOLUENESULPHONYL RADICALS FOR THE FORMATION OF ALLYL-, BENZYL-, CYCLOPROPYLCARBINYL-, SPIROCYCLOPROPYLCYCLOALKYL-, BICYCLOALKYL-, AND BICYCLOALKYL-4-TOLYLSULPHONES FROM ORGANOCOBALOXIMES
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4-Toluenesulphonyl iodide reacts thermally at alkylsulphone.Spiro- and bicyclo-alkyl compounds are also formed with other free radical precursors.The reactions are believed to take place through a chain mechanism in which cobaloxime(II), present adventitiously or formed by partial homolysis of the substrate, abstracts iodine from the toluenesulphonyl iodide to give the toluenesulphonyl radical, which attacks the organic ligand of the cobaloxime, preferably at the terminal olefinic carbon, thereby displacing cobaloxime(II) and giving the observed organic product.
- Ashcroft, Martyn R.,Bougeard, Peter,Bury, Adrian,Cooksey, Christopher J.,Johnson, Michael D.
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p. 403 - 416
(2007/10/02)
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