Green protocol for conjugate addition of amines to p-quinones accelerated by water

Amines undergo smooth conjugate addition to p-quinones in H₂O at ambient temperature in the absence of a catalyst to produce 2-aminoquinones in excellent yields. Significant rate acceleration of this reaction is observed in H₂O compared to organic solvents. H₂O played a dual role in simultaneously activating the p-quinone and amine. This new methodology constitutes an easy, highly efficient, and green synthesis of substituted p-quinones. Correspondence: J. S. Yadav, Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India.     

Original reaction of p-nitrobenzyl chloride with aldehydes using tetrakis(dimethylamino)ethylene (TDAE)

A series of disubstituted diarylethanols was prepared in moderate to good yields by reaction of p-nitrobenzyl chloride (1) with various aromatic aldehydes (2-12) in presence of tetrakis(dimethylamino)ethylene (TDAE).     

Free radical and isomerisation processes during the electrochemical fluorination of n-butyryl chloride, i-butyryl chloride and pivaloyl chloride in anhydrous hydrogen fluoride

Electrochemical perfluorination (ECPF) of the title compounds containing primary, secondary and tertiary carbon atoms was carried out in anhydrous hydrofluoric acid (AHF). Detailed analysis of major and minor products suggest that carbon chain isomerisation involving cyclo-propane intermediate is more prevalent during ECPF of i-butyryl chloride when compared to n-butyryl chloride. Simple statistical probability involving free radical intermediates also support this observation. ECPF involving cyclo-propane intermediate is even more prevalent in pivaloyl chloride containing three methyl substituents. In this case, perfluorinated cyclo-propane intermediates were also observed in the product sample. Distribution of minor perfluorinated and partially fluorinated products also suggest the predominant role of normal free radical pathway involving single-electron transfer.     

Novelties of solid-liquid phase transfer catalysed synthesis of p-toluenesulfonyl fluoride from p-toluenesulfonyl chloride

Organic sulfonyl fluorides are of interest owing to their insecticidal, germicidal and enzyme inhibitory properties. In the current work synthesis of p-toluenesufonyl fluoride was accomplished by reacting p-toluenesulfonyl chloride with solid potassium fluoride using PEG-400 as a catalyst under solid-liquid phase transfer catalysis (S-L PTC) at 30 °C. p-Toulenesulfonyl fluoride is used as peroxygen bleach activator. It also finds use in the treatment of Alzheimer's disease. The mechanism is based on homogeneous solubilization of solid. PEG forms a complex with metal cation which associates with the nucleophile and it participates in S_N2 type reaction. The reaction is intrinsically kinetically controlled. A complete theoretical analysis is done to determine both the rate constant and equilibrium constant from the same set of data. The activation energy and Gibbs free energy are also calculated.     

Novelties of solid-liquid phase transfer catalysed synthesis of p-toluenesulfonyl fluoride from p-toluenesulfonyl chloride

Organic sulfonyl fluorides are of interest owing to their insecticidal, germicidal and enzyme inhibitory properties. In the current work, synthesis of p-toluenesufonyl fluoride was accomplished by reacting p-toluenesulfonyl chloride with solid potassium fluoride using PEG-400 as a catalyst under solid-liquid phase transfer catalysis (S-L PTC) at 30 °C. p-Toluenesulfonyl fluoride is used as peroxygen bleach activator. It also finds use in the treatment of Alzheimer's disease. The mechanism is based on homogeneous solubilization of solid. PEG forms a complex with metal cation which associates with the nucleophile and it participates in SN₂ type reactions. The reaction is intrinsically kinetically controlled. A complete theoretical analysis is done to determine both the rate constant and equilibrium constant from the same set of data. The activation energy and Gibbs free energy are also calculated.     

Oxidation of secondary amines by molecular oxygen and cyclohexanone monooxygenase

Cyclohexanone monooxygenase from Acinetobacter calcoaceticus catalyzed the oxidation of tertiary and secondary amines to N-oxides and nitrones, respectively. The formation of a hydroxylamine intermediate was involved with secondary amines as starting substrates.     

A simple synthesis of ketone from carboxylic acid using tosyl chloride as an activator

An effective process for the conversion of carboxylic acid to ketone has been discovered. In this process, carboxylic acid has been activated using p-toluene sulphonyl group. Under the optimized condition, aromatic, aliphatic heteroaromatic carboxylic acids have been proved to be good substrates for this methodology. The byproduct of this reaction can be removed very easily during work up process. Also, one equivalent of organometallic reagent is sufficient to complete this transformation.     

Reaction of primary amines with Pt/C catalyst in water under microwave irradiation: a convenient synthesis of secondary amines from primary amines

Upon microwave irradiation in water, Pt/C converts primary amines into secondary amines in good yield via retro-reductive and reductive amination.     

Copper complex catalyzed asymmetric monosulfonylation of meso-vic-diols

Asymmetric desymmetrization of meso-vic-diols was performed by tosylation in the presence of copper(II) triflate and (R,R)-Ph-BOX as a catalyst. The method was successfully applied to asymmetric desymmetrization of cyclic and acyclic meso-vic-diols in high enantioselectivity with up to >99% ee.     

Application of 10‐ethyl‐acridine‐3‐sulfonyl chloride for HPLC determination of aliphatic amines in environmental water using fluorescence and APCI‐MS

A simple, sensitive method for the determination of aliphatic amines based on a sulfonylation reaction using 10‐ethyl‐acridine‐3‐sulfonyl chloride (EASC) as pre‐column labeling reagent with fluorescence detection and APCI‐MS identification has been developed. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by HPLC with an excitation maximum at λ_ex 270 nm and an emission maximum at λ_em 430 nm. Identification of derivatives was carried out by online post‐column MS in positive‐ion mode. Comparing with the widely used 5‐dimethylaminonaphthalene‐1‐sulfonylchloride (Dansyl‐Cl), EASC‐amine derivatives not only exhibited high fluorescence but also exhibited excellent MS ionizable potential. Detection limits obtained from 0.10 pmol injection, at a S/N of 3, were 4.0–12.7 fmol. The mean intra‐ and inter‐assay precision for all aliphatic amine levels were <3.84 and 3.21%, respectively. Excellent linear responses were observed with coefficients of >0.9995.     

Indium triflate-catalyzed allylation reactions of N-sulfonyl aldimines or N-alkoxycarbonylamino p-tolylsulfones with allyltrimethylsilane: synthesis of protected homoallylic amines

Indium triflate-catalyzed allylation reactions of N-sulfonyl aldimines or N-alkoxyloxycarbonylamino p-tolylsulfone with allyltrimethylsilane have been successfully developed to produce protected homoallylic amines.     

A simple one-pot procedure for the direct conversion of alcohols into alkyl nitriles using TsIm

A convenient and efficient one-pot preparation of nitriles from alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, treatment of alcohols with a mixture of NaCN, TsIm and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in refluxing DMF furnishes the corresponding alkyl nitriles in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.     

Asymmetric ring opening reaction of oxabenzonorbornadienes with amines promoted by iridium/NMDPP complex

As an efficient catalyst, the [Ir(COD)Cl]₂/NMDPP complex has been successfully applied to promote the asymmetric ring opening reaction of oxabenzonorbornadienes with various amines, which afforded the corresponding products in good yields (72–98%) with good enantioselectivities (80–90% ee).     

Reactions of vanadocene and its monochloride withp-toluenesulfonyl chloride

The reactions of Cp₂V and Cp₂VCl withp-toluenesulfonyl chloride were studied. Depending on the ratio of the reagents, the solvent, and other reaction conditions, the compoundsp-MeC₆H₄S0₂VCp₂Cl, (p-MeC₆H₄S0₂VCp)n or (p-MeC₆H₄S0₂VO)m are formed.Translated from_{Izvestiya Akademii Nauk. Seriya Khimicheskaya}, No. 5, pp. 1275–1278, May, 1996.     

A simple one-pot procedure for the direct conversion of alcohols into azides using TsIm

A facile and efficient method for one-pot conversion of alcohols into azides using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of NaN₃, TsIm and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in DMF affording the corresponding alkyl azides in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.     

Evaluation of stationary phases and gas chromatographic detectors for determination of amines in water

For the first time, a systematic overview deals with the advantages and disadvantages of several stationary phases (polar and non‐polar) and gas chromatographic detectors (flame ionization detector, nitrogen–phosphorus detector and MS) for the determination of 27 amines (aliphatic and aromatic amines and N‐nitrosamines) in water samples. To increase sensitivity (250 mL of sample was eluted with 150 μL of solvent) and matrix elimination, an automatic SPE system was employed prior to GC determination. The best results in terms of resolution and retention times were achieved using a column coated with 5% phenyl‐dimethylpolysiloxane (DB‐5). Capacity factor (k) values for the 27 amines increased with the rise in the polarity of the stationary phase, ranging from 3.0–27.7 and 2.2–14.4 for polar (polyethylene glycol) and non‐polar (DB‐5) columns, respectively. The detection limits of the method were 0.9–9 μg/L for flame ionization detector, 8–95 ng/L for nitrogen–phosphorus detector and 0.2–6.3 ng/L for MS. The precision was similar for the three detectors (RSD, 3.7–6.0%). The GC‐MS method was applied with a high degree of accuracy and precision to determine amines in real samples including tap, river, pond, well, swimming pool and wastewaters.     

Facile removal of tosyl chloride from tosylates using cellulosic materials,e.g., filter paper

Excess tosyl chloride used in the tosylation of alcohols is quickly and easily removed by reacting it with cellulosic materials, e.g., filter paper, and filtering.     

β-Cyclodextrin promoted aza-Michael addition of amines to conjugated alkenes in water

Highly efficient and environmentally benign aza-Michael additions of amines to α,β-unsaturated compounds catalyzed by β-cyclodextrin in water to produce the corresponding β-amino compounds in excellent yields under mild conditions are described. β-Cyclodextrin can be recovered and reused in subsequent reactions without loss of activity.     

A simple procedure for the esterification of alcohols with sodium carboxylate salts using 1-tosylimidazole (TsIm)

An efficient and selective method for esterification of alcohols using N-(p-toluenesulfonyl)imidazole (TsIm) is described. In this method, alcohols are refluxed with a mixture of RCO₂Na (R: alkyl and aryl), TsIm, and triethylamine in the presence of catalytic amounts of tetra-n-butylammonium iodide (TBAI) in DMF to afford the corresponding esters in good yields. This methodology is highly efficient for various structurally diverse alcohols with selectivity for ROH: 1° > 2° > 3°.     

Efficient method for the direct preparation of amides from carboxylic acids using tosyl chloride under solvent-free conditions

A simple, clean and highly efficient solvent-free procedure for the preparation of primary, secondary, tertiary and aromatic amides is described from the direct reaction of carboxylic acids and silica-supported ammonium salts, triethylamine (TEA) and tosyl chloride (TsCl) as condensing agent. The reaction proceeds rapidly in high yields at room temperature.