A simple convenient method for the generation of diborane from NaBH4 and I2

Treatment of NaBH₄ with I₂ in diglyme yields diborane which can be utilized conveniently for the preparation of a borane-N,N-diethylaniline complex and other borane-Lewis base complexes.     

Simple and highly efficient synthesis of oxaziridines by tetrabutylammonium Oxone

Oxygenation of various aldimines with tetrabutylammonium monoperoxysulfate produced the corresponding E- or a mixture of E- and Z-oxaziridines with very high yields (?90%) and good to excellent selectivities (75-100%) within 20 min to 10 h in CH₃CN at room temperature (∼25 °C). The E/Z isomer ratio critically depends on the stereo-electronic nature of the substituents in the oxaziridines, solvent, and the presence of Lewis acids and bases.     

A very simple method for the preparation of symmetrical disulfides

A serendipitiously discovered, extremely simple, fast and previously unreported method for the preparation of symmetrical aliphatic, aromatic and heteroaromatic disulfides is reported. Addition of sulfuryl chloride to an alkyl- or arylthiol in a 1:2 ratio under solvent free conditions or in dichloromethane solution produces the corresponding disulfides in nearly quantitative yields with the concomitant elimination of gaseous SO₂ and 2 equiv of HCl. Thus, optimally the reaction needs no work-up at all leaving the disulfide as the sole product in excellent yield. In dichloromethane solution, the reaction is conveniently carried out in a rotary evaporator by mixing the solvent, thiol and SO₂Cl₂ in a round-bottomed flask followed by evaporation of the volatiles.     

A novel method for the preparation of diborane from aluminum,ethyl chloride,boron oxide and hydrogen

A novel method is described for the preparation of diborane from aluminum, ethyl chloride, boron oxide and hydrogen via three steps; deoxyalkylation of boron oxide, hydrogenation of triethylboron and liberation of diborane. The triethylboron was prepared from aluminum, ethyl chloride and boron oxide directly at 85–110°C in 88% yield, with aluminum trichloride as by-product in 95% yield. In the presence of triethylamine and a hydrogen pressure of 130 kg/cm², the triethylboron was hydrogenated at 200°C for 2 hours to produce borane-triethylamine complex in 92% yield. The borane-triethylamine complex was treated again at 80°C with the aluminum trichloride collected from the first step to liberate diborane in 94% yield. The overall reaction yield was 76%.     

A simple and convenient one-pot method for the preparation of heteroaryl-2-imidazoles from nitriles

A simple, convenient and high-yielding one-pot method for the synthesis of 2-heterocycle-substituted imidazoles from the corresponding nitriles has been developed. The procedure is easily scaleable and the workup does not involve chromatography. This synthesis is also applicable to the preparation of imidazoles with electron-poor aryl substituents.     

A simple method for the preparation of 5-alkylsulfinyl-1-aryltetrazoles

A simple method is suggested for the preparation of 5-alkylsulfinyl-1-aryltetrazoles via oxidation of 5-alkylsulfanyltetrazoles with 34% peracetic acid in high yields under mild conditions.     

A facile and convenient method for synthesis of alkyl thiocyanates under homogeneous phase transfer catalyst conditions

A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide （TBAB） as a phase transfer catalyst. The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields. No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.     

A convenient synthesis and a NMR study of the diammoniate of diborane

DADB synthesis: The diammoniate of diborane (DADB) was synthesized in a new metathesis reaction between the diammoniate of monochloroborane and potassium borohydride in liquid ammonia. (1)H and (11)B?NMR spectra of DADB are reported. The stability in THF was examined by variable-temperature (11)B?NMR spectroscopy.     

A convenient procedure for the synthesis of allyl and benzyl ethers from alcohols and phenols

Allyl and benzyl ethers of alcohols can be prepared conveniently and in high yield with allyl and benzyl bromide in the presence of solid potassium hydroxide without use of any solvent. Phenols can be converted to allyl ethers but are inert to benzylation under above conditions.     

Rapid and highly selective epoxidation of alkenes by tetrabutylammonium monopersulfate in the presence of manganese meso-tetrakis(pentafluorophenyl)porphyrin and tetrabutylammonium salts or imidazole co-catalysts

Epoxidation of various alkenes in low to high yields (29-100%) and good to excellent selectivities (75-100%) was performed with tetrabutylammonium monopersulfate in the presence of meso-tetrakis(pentafluorophenyl)porphyrin as catalyst and tetrabutylammonium acetate or fluoride or imidazole as co-catalysts in CH₂Cl₂, in less than 10 min at room temperature (∼25 °C).     

A convenient method for the preparation of oxazaborolidine catalyst in situ using (S)-α,α-diphenylpyrrolidinemethanol,tetrabutylammonium borohydride,and methyl iodide for the asymmetric reduction of prochiral ketones

An oxazaborolidine catalyst is readily prepared in situ at 25 °C in THF using (S)-α,α-diphenylpyrrolidinemethanol and borane generated from tetrabutylammonium borohydride/CH₃I reagent system. The oxazaborolidine/BH₃ reagent system prepared in this way is useful for the reduction of prochiral ketones to the corresponding alcohols with up to 99% ee.     

Improved procedures for the generation of diborane from sodium borohydride and boron trifluoride

Improved procedures for the generation of diborane by the reaction of NaBH4 in triglyme or tetraglyme with the BF3 adducts of di-n-butyl ether, tert-butyl methyl ether, monoglyme, dioxane, and tetrahydropyran were developed. In these systems, generation of diborane requires 2-4 h at 25 degrees C (faster reactions take place at 50 degrees C). The byproduct NaBF4 precipitates from the reaction mixture at 25 degrees C as the reaction proceeds. The high-boiling glyme can be conveniently separated from the lower boiling carrier ethers by simple distillation of the latter. On the other hand, diborane was generated very slowly or not generated using the addition of each of six boron trifluoride-etherates (di-n-butyl ether, tert-butyl methyl ether, tetrahydrofuran, tetrahydropyran, dioxane, and monoglyme) to suspensions of sodium borohydride in the corresponding ether. However, diborane was generated rapidly and quantitatively by the addition of NaBH4 in triglyme (or tetraglyme) to the BF3 adduct of triglyme (or tetraglyme) at room temperature. No solid precipitation occurs during the reaction, making it convenient for large-scale applications. The pure solvent triglyme (or tetraglyme) can be easily recovered and recycled by either crystallizing or precipitating NaBF4 from the generation flask. New procedures for the generation of diborane were also developed by the reaction of NaBF4 with NaBH4 in triglyme (or tetraglyme) in the presence of Lewis acids such as AlCl3 and BCl3.     

Sodium borohydride or potassium carbonate-mediated intramolecular Michael addition: a general method for the synthesis of fused dihydrofuran and furan derivatives

A simple and convenient method for the synthesis of fused dihydrofuran derivatives using NaBH₄-mediated reductive cyclization and fused furan derivatives by K₂CO₃-mediated intramolecular Michael addition followed by acid-catalyzed methanol elimination has been developed.     

An efficient and convenient method for the preparation of disulfides from thiols using oxygen as oxidant catalyzed by tert-butyl nitrite

An efficient and convenient tert-butyl nitrite-catalyzed selective aerobic oxidation of thiols has been developed. Under the optimal reaction conditions, a number of thiol derivatives including aromatic thiols, heteroaromatic thiols and aliphatic thiols can be converted into their corresponding disulfides in good to excellent yields.     

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 simple and convenient procedure for the synthesis of 1-aminophosphonates from aromatic aldehydes

A simple, efficient, possible industrial process has been developed for the synthesis of 1-aminophosphonic acids from simple starting materials. As described below, treatment of aromatic aldehydes with ammonia and reaction with diethyl phosphite gives diethyl N-(arylmethylene)-1-aminoaryl methylphosphonates, which can be easily hydrolyzed to diethyl 1-aminoarylmethylphosphonates. This method is easy, rapid, and good yielding for the synthesis of 1-aminoalkylphosphonates from simple starting materials.     

一个简便合成二茂钛二芳氧基和水杨酸配合物的方法

用两相法合成了二茂钛二(五氯苯氧基)配合物,并对二茂钛(环取代)水杨酸配合物的合成法进行了改进,产率为70%-90%。     

A convenient method for the synthesis of α-Ketoesters from aldehydes

An efficient two step, two carbon homologation of aldehydes to α-ketoesters is described.     

A convenient method for the synthesis of roflumilast

A convenient synthetic method has been developed for the synthesis of roflumilast from 4-difluoromethoxy-3-hydroxybenzaldehyde and bromomethyl cyclopropane via O-alkylation, oxidation and N-acylation. With sodium hydroxide as alkali in the last step, the total yield of roflumilast can be up to 68.3 % and the purity of the target product reached 99.2 %. It was obvious that sodium hydroxide showed more economic advantage for scale-up production than sodium hydride or potassium tert-butoxide.