A simple, efficient, and highly selective method for the iodination of alcohols using ZrCl4/NaI

Iodination of primary, secondary, allylic, and benzylic alcohols giving their corresponding iodides was achieved with ZrCl₄/NaI in anhydrous CH₃CN with excellent yields and selectivities.     

Novel oxidative alpha-tosyloxylation of alcohols with iodosylbenzene and p-toluenesulfonic acid and its synthetic use for direct preparation of heteroaromatics

alpha-Tosyloxyketones and alpha-tosyloxyaldehydes were directly prepared from alcohols by treatment with iodosylbenzene and p-toluenesulfonic acid monohydrate in good yields. This method can be used for the direct preparation of thiazoles, imidazoles, and imidazo[1,2-a]pyridines from alcohols in good to moderate yields by the successive treatment with iodosylbenzene and p-toluenesulfonic acid monohydrate, followed by thioamides, benzamidine, and 2-aminopyridine, respectively.     

A convenient preparative method for cyclic triphosphenium bromide and chloride salts

Analytically pure chloride and bromide salts of two different cyclic triphosphenium cations are prepared by the reaction of PX3 (X=Cl, Br) in the presence of the halogen-scavenging reagent cyclohexene. For the brominated species, the neutral, volatile 1,2-dibromocyclohexane byproduct is readily removed under reduced pressure, and the desired salts are obtained in high yield. Reactions involving phosphorus trichloride are complicated by the formation of salts containing both chloride and hydrogen dichloride anions. Reactivity experiments on potential undesired halogenated diphosphine byproducts suggest that the formation of such species can be prevented by increasing the concentration of cyclohexene employed in the reaction.     

Chemoselective tetrahydropyranylation of alcohols and phenols using polystyrene supported aluminium chloride as a catalyst

A simple, efficient and highly chemoselective method for tetrahydropyranylation of alcohols and phenols has been developed by their reaction with 3,4-dihydro-2H-pyran at room temperature in the presence of a catalytic amount of polystyrene supported AlCl₃. The method is also highly selective for monoprotection of symmetrical diols.     

A simple and convenient method for the synthesis of S-aryl phosphorothioates catalyzed by cesium hydroxide

In the presence of a catalytic amount of cesium hydroxide, the corresponding S-aryl phosphorothioates can he obtained by the reactions of dialkyl phosphites with diaryldisulfides in excellent yields at room temperature, using DMSO as a solvent. The reaction mechanism was discussed. The method provides a new and expedient path for the preparation of $-aryl phosphorothioates.     

A new and convenient in-situ method of generating phenyl isocyanates from anilines using oxalyl chloride

A new and convenient method of generating phenyl isocyanates from anilines using oxalyl chloride is described. Acylation of a variety of substituted aniline hydrochlorides with oxalyl chloride affords the intermediate oxamic chlorides, which smoothly undergo thermal decomposition to the corresponding isocyanates.     

A convenient and general synthesis of 2-amino-1,3,4-thiadiazoles. Dehydration of acylthiosemicarbazides with methanesulfonic acid

2-Amino-5-alkyl and 2-amino-5-aryl-1,3,4-thiadiazoles were prepared by the dehydration of 2-acylthiosemicarbazides with molar equivalents of methanesulfonic acid in refluxing toluene. The synthesis appears to be general.     

An efficient and regioselective iodination of electron-rich aromatic compounds using N-chlorosuccinimide and sodium iodide

An efficient and regioselective method for iodination of electron-rich aromatic compounds was found using N-chlorosuccinimide and sodium iodide in AcOH with short reaction times. This method is also applicable to non-benzenoid aromatic or heteroaromatic compounds.     

A simple and efficient method for solvent-free iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid by grinding method

<正>Green,mild and efficient iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid in the solidstate by grinding under solvent-free conditions at room temperature.This method provides several advantages such as environmentally friendly,short reaction times,high yields,non-hazardous and simple work-up procedure.     

Regioselective iodination of phenol and analogues using N-iodosuccinimide and p-toluenesulfonic acid

Mild and highly regioselective monoiodination of phenol and analogues is achieved in high to excellent yields at room temperature with a combination of stoichiometric p-toluenesulfonic acid and N-iodosuccinimide.     

IBX-mediated alpha-hydroxylation of alpha-alkynyl carbonyl systems. A convenient method for the synthesis of tertiary alcohols

[reaction: see text] IBX (o-iodoxybenzoic acid) is an excellent reagent for the alpha-hydroxylation of alpha-alkynyl carbonyl compounds without giving dehydrogenation products. The convenient procedure proves to be useful for the construction of a variety of tertiary alcohols (55-91%) under mildly acidic conditions.     

A convenient method for the synthesis of N-hydroxyureas

Treatment of amines with 1-(4-nitrophenol)-N-(O-benzylhydroxy)carbamate yields the O-benzyl protected N-hydroxyureas. Hydrogenation of the O-benzyl protected N-hydroxyureas over 5% Pd/BaSO₄ cleanly gives the N-hydroxyureas in good yield. In addition to primary and secondary aliphatic and aromatic amines, this method converts amino sugars to the corresponding N-hydroxyureas without extensive protecting group chemistry.     

A convenient method for the preparation of primary amines using tritylamine

A simple method for the preparation of primary amines by treating N-tritylamines with trifluoroacetic acid has been established. The N-tritylamines were prepared by the reaction of alkyl halides or alkyl p-toluenesulfonates with tritylamine, or by the reaction of alkyl bromides with lithium tritylamide.     

A comparison of microwave-accelerated and conventionally heated iodination reactions of some arenes and heteroarenes, using ortho-periodic acid as the oxidant

A fast and simple method for the oxidative iodination of some activated arenes and heteroarenes, either under microwave irradiation or by conventional heating, is reported, using diiodine and ortho-periodic acid as the oxidant. The reactions were carried out in hot 95% ethanol under a reflux condenser. For the microwave assisted reactions, the reaction times were always notably shortened, but the yields were nearly the same as those afforded by the conventional method.     

A convenient method for the preparation of barbituric and thiobarbituric acid transition metal complexes

A convenient method for the preparation of barbiturate transition metal complexes: (i) Cr(3+), Mn(2+), Fe(3+), Zn(2+) and Cd(2+) ions with barbituric acid (H(2)L) and (ii) Cr(3+) and Mo(5+) with 2-thiobarbituric acid (H(2)L') was reported and this has enabled seven complexes to be formulated as: [Cr(HL)(2)(OH)(H(2)O)].H(2)O, [Mn(HL)(2)(H(2)O)(2)], [Fe(2)(L)(OH)(3)(H(2)O)(4)].2H(2)O, [Zn(HL)(2)], [Cd(HL)(2)], [Cr(HL')(OH)(2)(H(2)O)].H(2)O and [Mo(HL')(2)]Cl. These new barbiturate complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, (1)H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that, all complexes of barbituric and 2-thiobarbituric acids are non-electrolytes except for [Mo(HL')(2)]Cl. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligands and their complexes are used to identify the mode of coordination. Kinetic and thermodynamic parameters such as: E, DeltaH, DeltaS and DeltaG are estimated according to the DTG curves. The two ligands and their complexes have been studied for their possible biological antifungal activity.     

A simple and convenient method for preparation of carboxylic acid alkyl esters, phenolic and thioesters using chlorodiphenylphosphine/I2 and imidazole reagent system

Condensation of carboxylic acids with alcohols, phenols and thiols proceeded smoothly to afford carboxylic acid alkyl esters, phenolic esters and thioesters by using the combination of chlorodiphenylphosphine, imidazole and molecular iodine in refluxing acetonitrile. Esterification with this mixed reagent system gave the corresponding products in excellent yields. The phosphorus-containing byproduct was simply removed from the organic phase by basic aqueous workup without the need for chromatography purification.     

Spectrofluorimetric method for determination of aluminium with chromotropic acid and its application to water samples

A rapid and sensitive method for the trace level determination of aluminium based on the formation of a 1:1 complex with chromotropic acid (1,8-dihydroxynaphthlene-3,6-disulfonic acid) in an methanol medium is reported. The fluorescence intensity of the system was 50 times greater than that of the system without aluminium. This method is very sensitive and selective for the direct determination of aluminium ion. The fluorescence is excited at 346 nm and measured at 370 nm. The optimum conditions are a chromotropic acid concentration of 5.0 ml (1.0x10(-4) M) and pH 4.0+/-0.5 (acetic acid-sodium acetate buffer). The fluorescence intensity is a linear function of the concentration of Al(III) in the range 2-100 ng ml(-1) and the detection limit is 1.0 ng ml(-1). The method has been applied successfully to the determination of trace amount of Al(III) in tap, river and sea-water samples.