Catalytic oxidation of thiols to disulfides using iodine and CeCl3·7H2O in graphite

A very simple procedure for the efficient oxidation of thiols to disulfides catalyzed by I₂/CeCl₃·7H₂O in graphite and ethyl acetate as the solvent, in an open system at room temperature is described. The reaction proceeds cleanly under mild conditions and was performed with aromatic, aliphatic, and heterocyclic thiols.     

CeCl3·7H2O/IBX-promoted oxidation of 3-alkylindoles to 3-hydroxyoxindoles

3-Alkylindoles undergo smooth oxidation with IBX in the presence of CeCl₃·7H₂O in aqueous acetonitrile at ambient temperature to afford the corresponding 3-hydroxyoxindoles in high yields. This method is very useful for the direct preparation of 3-hydroxyoxindoles from 3-alkylindoles. Operational simplicity, mild and neutral reaction conditions in aqueous solution are the key features of this protocol.     

Glycerin and CeCl3·7H2O: a new and efficient recyclable medium for the synthesis of bis(indolyl)methanes

Glycerin and CeCl₃·7H₂O were successfully used in recyclable catalytic system for the synthesis of several bis(indolyl)methanes in good to excellent yields through the reaction of indoles with aldehydes. The method is applicable to aliphatic and aromatic aldehydes, and the mixture of glycerin and CeCl₃·7H₂O can be reused up to five times without special treatment and with comparable yields.     

CeCl3·7H2O/AcCl-catalyzed Prins-Ritter reaction sequence: a novel synthesis of 4-amido tetrahydropyran derivatives

Homoallylic alcohols, carbonyl compounds and nitriles undergo a smooth tandem Prins-Ritter type cyclization in the presence of CeCl₃·7H₂O/AcCl at ambient temperature to produce 4-amido tetrahydropyrans in high yields with all cis-selectivity. Spirocyclic 4-amido tetrahydropyrans are obtained in the case of cyclic ketones.     

CeCl3·H2O/NaI-Promoted stereoselective synthesis of 2,4-disubstituted chiral tetrahydroquinolines

d-Glycals readily undergo cyclization with aryl amines in the presence of CeCl₃·7H₂O-NaI under mild and neutral conditions to afford a novel sugar derived tetrahydroquinoline derivatives in good yields with high stereoselectivity. The stereochemistry of the products was assigned by using various NMR studies.     

The CeCl3·7H2O-NaI system as promoter in the synthesis of functionalized trisubstituted alkenes via Knoevenagel condensation

The arylidene malonates with two different geminal carboxylate functions, a suitable class of substrates of several synthetic and pharmacological studies, are easily available through Knoevenagel condensation of ethyl tert-butyl malonate and different aromatic aldehydes. The results have increased the potentialities of CeCl₃·7H₂O-NaI system as a type of water-tolerant green Lewis acid promoter for carbon-carbon bond forming procedures.     

Modular CeCl3·7H2O-catalyzed multi-component synthesis of 1,2,3,4-tetrasubstituted pyrroles under microwave irradiation and their further trichloroisocyanuric acid-mediated conversion into 5-sulfenylpyrrole derivatives

A modular, multicomponent synthesis of 1,2,3,4-tetrasubstituted pyrroles promoted by the inexpensive CeCl₃·7H₂O, is reported. The reaction was carried out under microwave irradiation, affording good yields of products in short time. Scope and limitations were explored and a plausible reaction mechanism is discussed. The resulting heterocycles were smoothly and efficiently converted into their corresponding 5-arylsulfenyl derivatives by reaction with diaryl disulfides and trichloroisocyanuric acid in EtOAc.     

The first example of the C-3 alkylation of indoles with cyclopropyl ketones promoted by CeCl3·7H2O/LiI

Indoles undergo smooth alkylation with cyclopropyl ketones in the presence of the CeCl₃·7H₂O/LiI reagent system in refluxing acetonitrile under neutral conditions to produce the corresponding C-3 substituted indole derivatives in good to high yields and with high selectivity. The use of CeCl₃·7H₂O/LiI makes this method simple, convenient, and cost-effective.     

Anhydrous CeCl3 catalyzed C3-selective propargylation of indoles with tertiary alcohols

Anhydrous CeCl₃ was successfully used as catalyst for the synthesis of several 3-propargyl indoles in good yields through the reaction of indole with propargyl alcohols in nitromethane.     

Study of conventional versus microwave-assisted reactions of 3,4-epoxyalcohols by CeCl3·7H2O: Synthesis of tetrahydrofurans and 1-chloro-3-substituted-2-propanols

3,4-Epoxyalcohols undergo regioselective cyclization in the presence of CeCl₃·7H₂O in ref1uxing acetonitrile to afford tetrahydrofuran derivatives in good yields. On the other hand epoxyalcohols afforded 1-chloro-3-substituted-2-propanols under microwave irradiation using CeCl₃·7H₂O supported on SiO₂ under solvent-free conditions.     

CeCl3·7H2O: an efficient and reusable catalyst for the preparation of β-acetamido carbonyl compounds by multi-component reactions (MCRs)

A convenient method for the preparation of β-acetamido carbonyl compounds is described by multi-component reactions of aromatic aldehydes, enolizable ketones or β-keto esters and acetonitrile in the presence of acetyl chloride and 10 mol % CeCl₃·7H₂O at room temperature.     

Crystal growth of Ce2O(CO3)2·H2O in aqueous solutions: Film formation and samarium doping

Crystalline cerium oxide carbonate hydrate (Ce₂O(CO₃)₂·H₂O) was grown in aqueous solutions at a low temperature of 80 °C under ambient pressure. When cerium nitrate was used as a starting material, large Ce₂O(CO₃)₂·H₂O particles were precipitated through homogeneous nucleation and subsequent fast crystal growth. In contrast, the usage of cerium chloride was found to promote the preferential precipitation of Ce₂O(CO₃)₂·H₂O on foreign substrates through heterogeneous nucleation and slow crystal growth. This phenomenon was applied to a chemical bath deposition of Ce₂O(CO₃)₂·H₂O films. Immersion of glass substrates in the solution at 80 °C for typically 24 h resulted in formation of solid films with a unique morphology like a micrometer-scale brush. It was also found that samarium could be incorporated into Ce₂O(CO₃)₂·H₂O during the crystal growth in the solutions, as evidenced by characteristic photoluminescence of Sm³⁺ in heating products of CeO₂. These results suggest that rare-earth oxide carbonate hydrates with a variety of compositions and morphologies can be synthesized from the aqueous solutions.     

Selective addition of H2O to fullerene C60 catalyzed by Ti, Zr, and Hf catalysts

Selective addition of H₂O to fullerene C₆₀ catalyzed by Cp₂MCl₂ (M = Ti, Zr, Hf) catalysts to yield 1-hydroxy-1,2-dihydrofullerene has been realized for the first time.     

Alumina supported-CeCl3·7H2O-NaI: an efficient catalyst for the cyclization of 2′-aminochalcones to the corresponding 2-aryl-2,3-dihydroquinolin-4(1H)-ones under solvent free conditions

We recently advanced silica gel supported-TaBr₅ as an efficient catalyst for the isomerization of 2′-aminochalcones to the corresponding 2-aryl-2,3-dihydroquinolin-4(1H)-ones under solvent free conditions (Tetrahedron Lett. 2006, 47, 2725-2729). This conversion can be further improved through the use of more economic alumina supported-CeCl₃·7H₂O-NaI, providing high yields of up to 98% at lower reaction temperatures. This stable catalyst is easily prepared, active under solvent-free conditions and employed under environmentally friendly conditions.     

Fe(ClO4)3·×H2O-Catalyzed direct C-C bond forming reactions between secondary benzylic alcohols with different types of nucleophiles

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.     

Nd(Gly)2Cl3·3H2O和Pr(Ala)3Cl3·3H2O的热力学性质

利用精密自动绝热热量计测定了Nd(Gly)₂Cl₃·3H₂O在80-357K和Pr(Ala)₃Cl₃·3H₂O在80-374K温区的热容. 根据两个化合物的热容计算出了相对于参考温度298.15K的热力学函数(H_T?H_298.15)和(S_T?S_298.15). 根据热重(TG)分析结果, 提出了这两个稀土化合物可能的热分解机理. 利用溶解-反应恒温热量计测定相关化合物的溶解焓并设计盖斯热化学循环, 计算出了两个化合物的标准摩尔生成焓.     

Combining AlCl3·6H2O and an ionic liquid to prepare chlorohydrin esters from glycerol

We describe here the first example in which glycerol has been transformed into chlorohydrin esters using an ionic liquid and hydrated aluminium chloride. The method avoids using Crown-18 ether, which was needed to obtain a similar yield when KCl was used. Alkyl and aryl acids can be used, although yields are very dependent on the carboxylic acid used.     

FeCl3·6H2O-promoted skeleton-rearrangement of 1-substituted-3-benzazepines: substrate extension and product utilization

FeCl₃·6H₂O-promoted skeleton-rearrangement of 1-substituted-3-benzazepines was further exploited. Both 1-aryl- and 1-alkyl- or 1-alkenyl-benzazepines underwent this reaction smoothly. The rearrangement products were used to prepare a series of novel derivatives containing both tetrahydroisoquinoline (THIQ) and tetrahydropyrimidin-4(1H)-one scaffolds through a Mannich-type process.     

CeCl3·7H2O: a highly efficient catalyst for the synthesis of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxide

An efficient and simple protocol is reported for the synthesis of a new class of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxides in good to excellent yield (88–95%) via Michaelis–Arbuzov rearrangement. Condensation of diamido phosphite with various halides at 60 °C using CeCl₃·7H₂O as a highly efficient catalyst afforded the products within a short period of reaction time. This procedure is mild, efficient, and non-toxic and stability of the catalyst is the merit of this process. Therefore, this protocol being environmentally benign and efficient, serves as an alternative procedure for the preparation of the title compounds.     

Synthesis and thermochemistry of MgO·3B2O3·3.5H2O

A new magnesium borate MgO·3B₂O₃·3.5H₂O has been synthesized by the method of phase transformation of double salt and characterized by XRD, IR and Raman spectroscopy as well as by TG. The structural formula of this compound was Mg[B₆O₉(OH)₂]·2.5H₂O. The enthalpy of solution of MgO·3B₂O₃·3.5H₂O in approximately 1 mol dm⁻³ HCl was determined. With the incorporation of the standard molar enthalpies of formation of MgO(s), H₃BO₃(s), and H₂O(l), the standard molar enthalpy of formation of −(5595.02±4.85) kJ mol⁻¹ of MgO·3B₂O₃3.5H₂O was obtained. Thermodynamic properties of this compound was also calculated by group contribution method.