Recent advances in asymmetric synthesis of 2-substituted indoline derivatives

Recent advances in asymmetric synthesis of 2-substituted indoline derivatives are discussed.     

IBX-mediated one-pot synthesis of benzimidazoles from primary alcohols and arylmethyl bromides

A variety of primary alcohols are shown to be converted to the corresponding benzimidazoles in one pot by employing IBX and o-phenylenediamine in DMSO at room temperature. o-Iodobenzoic acid is the end product of IBX, which is employed in 1.0 equiv. Arylmethyl bromides are also shown to be converted likewise to benzimidazoles in moderate yields in one pot, albeit at slightly elevated temperatures.     

One-pot copper-catalyzed synthesis of 2-substituted benzothiazoles from 2-iodoanilines,benzyl chlorides and elemental sulfur

An efficient one-pot three-component reaction of 2-iodoanilines, benzyl chlorides and elemental sulfur to form 2-substituted benzothiazoles in satisfactory yields (up to 98%) has been described. The reaction tolerated a wide range of functional groups on the aromatic ring. And heterocycle methylene chlorides substrates were also found to be compatible.     

Facile one-pot preparation of 2-arylpropionic and arylacetic acids from cyanohydrins by treatment with aqueous HI

A novel one-pot two-step procedure has been developed to synthesize highly substituted 2-arylpropionic and arylacetic acids, by treatment with aqueous HI, from cyanohydrins. The hydrogenolytic reduction of α-hydroxy-2-arylpropionic acids was the key step of the process and the optimization of the reaction conditions led to identify aqueous HI as an appropriate and selective reagent for the reductive deoxygenation of cyanohydrins. The synthetic route described a general and efficient strategy for the preparation of large libraries of phenylacetic and phenylpropionic acids derivatives.     

Imidazolium chloride-catalyzed synthesis of benzimidazoles and 2-substituted benzimidazoles from o-phenylenediamines and DMF derivatives

A facile, general, and economical synthesis of diversely functionalized benzimidazoles and 2-substituted benzimidazoles has been realized via the imidazolium chloride-catalyzed cyclization of o-phenylenediamines with DMF derivatives. This protocol shows a broad substrate scope for aliphatic, aromatic, and heteroaromatic amides. A series of benzimidazoles and 2-substituted benzimidazoles have been obtained in moderate to excellent yields.     

A new approach to the one-pot synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles from N-tributylstannyltetrazoles

A new approach to the synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles was developed.     

Deep eutectic solvent-assisted one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives

Choline chloride–urea-based deep eutectic solvent (DES) has been found to be a highly effective catalyst and reaction medium for the one-pot synthesis of 2-aminothiazole and 2-aminoxazole derivatives. Three-component reactions of active methylene compounds, urea or thiourea and N-bromosuccinimide NBS in deep eutectic solvent furnished structurally diverse 2-aminoxazoles and 2-aminothiazoles in good to excellent yields under mild reaction conditions and short reaction times. DES is inexpensive, biodegradable and more accessible in any laboratory and industry.     

A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

A novel one-pot synthesis of hydroximoyl chlorides and 2-isoxazolines using N-tert-butyl-N-chlorocyanamide

Treatment of aldoximes with N-tert-butyl-N-chlorocyanamide gave hydroximoyl chlorides in quantitative yields in less than a minute, which on dehydrohalogenation in the presence of triethylamine gave the corresponding nitrile oxides. The nitrile oxides underwent 1,3-dipolar addition to dipolarophiles and gave 2-isoxazolines in excellent yields under mild conditions.     

2-取代-环戊烯酮及其衍生物的简易合成

本文报道以2-氯环戊酮的加成重排反应合成2-取代环戊酮。如再引入硫硫双键,则可合成2-取代环戊烯酮。取代环戊酮和取代环戊烯酮是合成药物和合成香料的重要中间体。     

Convenient synthesis of fluorazone derivatives by one-pot pyrrolation/cyclization of anthranilic acids

A series of fused heterocyclic compounds based on a fluorazone structure has been prepared from anthranilic or ortho-aminoheteroaryl carboxylic acids by one-pot sequential pyrrolation/cyclization catalyzed by 4-chloropyridine hydrochloride, in generally good yield.     

A facile one-pot synthesis of 2-o-cyanoaryl oxazole derivatives mediated by CuCN

A convenient, inexpensive and effective approach to the synthesis of 2-o-cyanoaryl oxazole derivatives has been developed. Generally, the copper-mediated cyclization/coupling reactions afforded corresponding 2-cyanoaryl oxazoles and oxazolines in moderate to excellent yields. The functionalized oxazole derivatives may be useful in biological chemistry and medicinal science. Our investigation indicates that the formation of the oxazole ring might favor the CC bond forming process on the ortho-position of the aryl ring. And CuCN plays dual roles as a Lewis acid catalyst and a C-nucleophile in this transformation.     

One pot synthesis of 2-phenylbenzoxazoles by potassium cyanide assisted reaction of o-aminophenols and benzaldehydes

The 2-phenylbenzoxazoles were obtained in moderate to good yields by reaction of the substituted o-aminophenols with benzaldehydes in the presence of one equivalent of potassium cyanide as an equimolecular catalyst in N,N-dimethylformamide at room temperature.     

A one-pot two-step microwave-assisted synthesis of N1-substituted 5,6-ring-fused 2-pyridones

A fast, versatile and practical one-pot, two-step microwave-assisted protocol for the direct synthesis of N1-substituted 5,6-ring-fused 2-pyridones has been developed. The present method proved to be effective on a series of commercially available aldehydes, ketones and amines and could be profitably exploited in drug-discovery settings for the rapid identification of biologically relevant hit compounds.     

Solvent-free one-pot synthesis of 2-pyridone derivatives

An efficient synthesis of methyl 4-hydroxy-6-oxo-1,6-dihydro-2-pyridine carboxylates is described.This involves three component reactions between primary alkyl amines,malonyl dichloride and methyl propiolates.     

New approach to the synthesis of 2,3-substituted γ-aminobutyric acids and their derivatives

A new approach to the synthesis of 2,3-substituted γ-aminobutyric acids is proposed. This method consists of the selective catalytic reduction of substituted 3-cyanopropanoic acid esters, which are generated in high yield in the reaction of disubstituted cyclopropenes with sodium cyanide in the corresponding alcohol.     

A one-pot synthesis of isoindolin-1-imine derivatives

A one-pot procedure was developed for the synthesis of isoindolin-1-imine derivatives by a simple three-component condensation of 2-cyanobenzaldhyde, ammonium acetate, and 4-hyroxycoumarin derivatives or 1,3-dicarbonyl compounds or 4-hydroxyquinolin-2(1H)-one in ethanol under reflux for 20–60 min with excellent yields. The advantages of this procedure are operational simplicity, excellent yields, and short reactive time, without catalyst, easy workup, and green environmental impact.     

Three-component one-pot synthesis of N-arylsulfonyl-2-iminocoumarins

A one-pot, synthesis of N-arylsulfonyl-2-iminocoumarins is developed at ambient temperature by the reaction of 2-hydroxybenzaldehydes, arylacetonitriles, and aryl sulfonyl chlorides using DABCO as a base in a bio-mass-derived green solvent 2-MethylTHF. A simple telescoped process in which 2H-chromen-2-imines are formed in situ by the condensation of 2-hydroxybenzaldehyde and arylacetonitriles. The formed imines are further reacted with arylsulfonyl chlorides in a one-pot approach to obtain the target compounds. This protocol provides access to 3-aryl-N-arylsulfonyl-2-iminocoumarins in a practical and environmentally benign way avoiding cumbersome steps of intermediate syntheses and purifications.     

Efficient one-pot synthesis of 2-oxo-1,9a-dihydro-2H-pyrido[1,2-a]pyrimidine derivatives

Pyridines react smoothly with dialkyl acetylenedicarboxylates in the presence of isocyanates to produce dialkyl 2-oxo-1,9a-dihydro-2H-pyrido[1,2-a]pyrimidine 3,4-dicarboxylates in excellent yields.     

A one-pot efficient synthesis of highly functionalized 5,6-dihydronaphthalenes from 2H-pyran-2-one

A one-pot efficient synthesis of highly functionalized 5,6-dihydronaphthalenes has been delineated through carbanion-induced ring transformation of 2H-pyran-2-ones by 2-cyclohexenone.