共查询到20条相似文献,搜索用时 15 毫秒
1.
Valiollah Mirkhani Shahram TangestaninejadBahram Yadollahi Ladan Alipanah 《Tetrahedron》2003,59(41):8213-8218
Epoxides can be cleaved in a regio- and stereoselective manner under neutral conditions with alcohols and acetic acid in the presence of catalytic amounts of decatungstocerate(IV) ion, ([CeW10O36]8−), affording the corresponding β-alkoxy and β-acetoxy alcohols in high yields. In water, ring opening of epoxides occurs with this catalyst to produce the corresponding diols in good yields. 相似文献
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Georgiy B. Shul'pin Yuriy N. Kozlov Lidia S. Shul'pina Pavel V. Petrovskiy 《应用有机金属化学》2010,24(6):464-472
Trinuclear carbonyl hydride cluster, Os3(CO)10(µ‐H)2, catalyzes oxidation of cyclooctane to cyclooctyl hydroperoxide by hydrogen peroxide in acetonitrile solution. The hydroperoxide partly decomposes in the course of the reaction to afford cyclooctanone and cyclooctanol. Selectivity parameters obtained in oxidations of various linear and branched alkanes as well as kinetic features of the reaction indicated that the alkane oxidation occurs with the participation of hydroxyl radicals. A similar mechanism operates in transformation of benzene into phenol and styrene into benzaldehyde. The system also oxidizes 1‐phenylethanol to acetophenone. The kinetic study led to a conclusion that oxidation of alcohols does not involve hydroxyl radicals as main oxidizing species and apparently proceeds with the participation of osmyl species, ‘Os?O’. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Iron-mediated sp-sp3 C-C bond formation through the cross dehydrogenative coupling(CDC) of terminal alkynes with benzylic ethers or alkanes has been developed.The inexpensive iron salt is used as the catalyst to make this transformation environmentally benign.Iron-mediated sp-sp3 C-C bond formation through the cross dehydrogenative coupling(CDC) of terminal alkynes with benzylic ethers or alkanes has been developed.The inexpensive iron salt is used as the catalyst to make this transformation environmentally benign. 相似文献
5.
Shekaraiah Devari Ramesh Deshidi Manjeet Kumar Arvind Kumar Simmi Sharma Masood Rizvi Manoj Kushwaha Ajai Prakash Gupta Bhahwal Ali Shah 《Tetrahedron letters》2013
A mild and highly chemoselective approach to oxidation of allylic, electron rich/deficient benzylic, and heterocyclic alcohols employing catalytic quantities of K2[OsO2(OH)4] (3 mol %) and chloramine-T (50 mol %) is described. The protocol offers short reaction times (25 min–2 h), controlled oxidation, and tolerance to a variety of substrates. A systematic mechanistic study based on the LC-ESI-MS/MS reveals the presence of imidotriooxoosmium species which further reacts with alcohol to give the oxidized product. 相似文献
6.
Liang XuMark L. Trudell 《Tetrahedron letters》2003,44(12):2553-2555
Chromium(III) acetylacetonate was found to be an efficient catalyst (10 mol%) for the oxidation of alcohols to aldehydes and ketones with periodic acid (1.5 equiv.) in acetonitrile at room temperature. 相似文献
7.
Xiaoxiang Zhang 《Journal of organometallic chemistry》2011,696(1):331-337
An efficient synthetic method to prepare di- and trisubstituted 2-aryloxazoles based on Yb(OTf)3 catalyzed cyclization of trisubstituted propargylic alcohols with aryl amides is described. The reaction was accomplished in moderate to excellent product yields and with complete regioselective control. The mechanism is suggested to involve activation of the starting alcohol by the metal catalyst that results in its ionization. Subsequent cyclization of this newly generated carbocationic species with the aryl amide then affords the oxazole. In view of the mild conditions along with the low cost, commercially availability of Yb(OTf)3 and its high tolerance to air and moisture, the present synthetic approach offers an operationally simplistic and convenient route to this important aromatic heterocycle. 相似文献
8.
Ponnaboina Thirupathi 《Tetrahedron》2010,66(16):2995-4577
A mild and efficient Fe(ClO4)3·×H2O-catalyzed direct C-C bond coupling reactions of 1,3-dicarbonyl compounds, electron-rich arenes and heteroarenes and 4-hydroxycoumarin with secondary benzylic alcohols have been described. The benzylation of electron-rich arenes and heteroarenes leads to the synthesis of bis-symmetrical triarylmethanes. The present method is also applied to synthesis of an anti-coagulant compound, 4-hydroxy-3-(1,2,3,4-tetrahydronaphthalen-1-yl)-2H-chromen-2-one (Coumatetralyl (B)) from commercially available substrates was obtained in 85% yield. The advantages of this protocol are broad scope, mild conditions, use of inexpensive catalyst and simplicity of operation since water is the only side product. 相似文献
9.
J.S. Yadav B.V. Subba Reddy A. Srinivas Reddy 《Journal of molecular catalysis. A, Chemical》2008,280(1-2):219-223
Indoles undergo smooth alkylation with benzylic alcohols on the surface of 10 mol% of phosphomolybdic acid supported on silica gel under mild conditions to produce C-3 benzylated-indoles in high yields and with high selectivity. This method offers significant advantages such as high conversions, short reaction times, mild reaction conditions, cleaner reaction profiles, high selectivity and low cost of the heterogeneous catalyst. 相似文献
10.
以纳米磁性材料Fe3O4, ZrOCl2·8H2O和硫酸为原料,在不同焙烧温度下制备了纳米磁性固体酸催化剂SO42–/Zr(OH)4-Fe3O4.详细表征了该磁性固体酸的SO42–负载量、酸分布、表面形貌和孔结构等特性.在含有硝基和氰基强吸电子基苯甲醛的不对称水相Aldol反应中, SO42–/Zr(OH)4-Fe3O4表现出优良的催化性能(83%–100%收率,86.0%–95.6% eeanti和anti/syn =88–96/12–4).该类磁性固体酸可在外加磁体作用下定量地从催化反应体系中分离并回收使用,重复使用5次未见显著失活. 相似文献
11.
以纳米磁性材料Fe3O4, ZrOCl2·8H2O和硫酸为原料,在不同焙烧温度下制备了纳米磁性固体酸催化剂SO42–/Zr(OH)4-Fe3O4.详细表征了该磁性固体酸的SO42–负载量、酸分布、表面形貌和孔结构等特性.在含有硝基和氰基强吸电子基苯甲醛的不对称水相Aldol反应中, SO42–/Zr(OH)4-Fe3O4表现出优良的催化性能(83%–100%收率,86.0%–95.6% eeanti和anti/syn =88–96/12–4).该类磁性固体酸可在外加磁体作用下定量地从催化反应体系中分离并回收使用,重复使用5次未见显著失活. 相似文献
12.
Michael Andreas Tandiary Masashi Asano Taiki Hattori Satoshi Takehira Yoichi Masui Makoto Onaka 《Tetrahedron letters》2017,58(20):1925-1928
The solid acid, tin hydroxide-embedded montmorillonite, catalyzes the unprecedented alkylation of various silicon enolates with primary, secondary and tertiary benzylic alcohols as well as secondary allylic alcohols. The acid catalysis of Sn-Mont was not only higher than that of the other ion-exchanged montmorillonites (M-Mont; M = H, Ti, Fe and Al), but also higher than that of the typical homogeneous acid catalysts such as BF3·OEt2, TMSOTf and TfOH. 相似文献
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A new titanium(IV) complex has been developed for the effective enantioselective alkynylation of phenylacetylene addition to aldehydes. The titanium(IV) complex was readily prepared in situ from (R)‐C‐(7,7‐dimethyl‐2‐oxo‐bicyclo[2.2.1]hept‐1‐yl)‐(1R,2S)‐N‐(2‐hydroxy‐1,2‐diphenyl‐ethyl)‐methanesulfonamide (1h) and tetraisopropyl titanate [Ti(i‐OPr)4]. A variety of aromatic aldehydes and α,β‐unsaturated aldehydes were found to be suitable substrates in the presence of the camphor sulfonylated amino alcohol titanium(IV) complex [10 mol% 1h, 40 mol% Ti(i‐OPr)4]. The desired propargylic alcohols were afforded with high isolated yields (up to 90%) and moderate enantioselectivities (up to 65% ee) under mild conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
A novel catalytic system including NiCl2-NHC ligand precursor has been developed for the preparation of imines from amines and ketones from alcohols. Owing to the acceptorless dehydrogenation pathway for this reaction, the hydrogen gas is liberated as a by-product. The active catalyst is generated in situ by the reaction of nickel (II) chloride, bis (imidazolium) chlorides and potassium tert-butoxide. The products were obtained in good to excellent yields and a wide variety of amines and ketones were applied successfully in this protocol. 相似文献
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Margherita Barbero Silvano CadamuroStefano Dughera Marta RucciGiulia Spano Paolo Venturello 《Tetrahedron》2014
A simple and efficient alkylation of aromatic and heteroaromatic compounds via the direct SN1-type nucleophilic substitution of benzylic alcohols in the presence of catalytic amounts of the strong Brønsted acid o-benzenedisulfonimide under neat conditions is herein reported. A library of di- and triaryl (and heteroaryl) methanes was prepared in good yields and high regioselectivity. The observed reactivity was shown to be in agreement with Mayr's nucleophilicity and electrophilicity scales. 相似文献
17.
Sonal M. Patel Uma V. Chudasama Pralhad A. Ganeshpure 《Reaction Kinetics and Catalysis Letters》2002,76(2):317-325
Metal(IV) phosphates of tin, zirconium and titanium in different morphological forms, viz. amorphous, calcined and crystalline, have been used as catalysts for selective cyclodehydration of 1,4-butanediol to tetrahydrofuran. A comparative study of the three catalysts for the above reaction has been carried out to understand the effect of their composition and morphology on the catalytic activity. 相似文献
18.
《应用有机金属化学》2017,31(9)
An easily synthesized water‐soluble ruthenium complex, [C6H5CH2N(CH3)2H]2[Ru(dipic)Cl3] (dipic =2,6‐pyridinedicarboxylate), as a catalyst showed high efficiency in the oxidation of alkanes and secondary alcohols to their corresponding ketones under solvent‐free and low‐catalyst‐loading conditions. This catalytic system could tolerate a variety of substrates and gave the corresponding ketones in good to excellent yields. The products were easily separated and purified due to the water solubility of the ruthenium complex. 相似文献
19.
The kinetics and mechanism of Ru(III)-catalyzed oxidation of some aliphatic alcohols by trichloroisocyanuric acid (TCICA)
has been studied in aqueous HOAc-HClO4 medium. The reaction is zero order in [TCICA], fractional order in [alcohol] and first order in [Ru(III)]. The reaction is
insensitive towards changes in acid concentration. The rate is not affected by an increase in [Cl−]. The polar reaction constant (ρ*) was found to be −1.27 at 308 K. A mechanism involving complex formation between the substrate
and catalyst in the fast equilibrium step followed by its decomposition in a slow step is proposed. 相似文献
20.
Khusnutdinov R. I. Schadneva N. A. Baiguzina A. R. Dzhemilev U. M. 《Russian Chemical Bulletin》2002,51(6):1065-1067
The Mn(acac)3—RCN—CCl4 system was found to be efficient for the oxidation of secondary alcohols into the corresponding ketones in 80—93% yields. The oxidation proceeds through the formation of alkyl hypochlorites, which are generated from CCl4 and the alcohols in the presence of the Mn(acac)3—RCN catalytic system (R = Me, Et, and Ph). 相似文献