Synthesis and characterization of 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles

The synthesis of a new set of selenadiazoles, 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles ( 4 ) derived from 2‐[4‐methyl‐4‐nitro‐1,3‐diarylpentylidene]‐1‐hydrazinecarboxamide ( 3 ) has been reported. THF has been found to be the solvent of choice for this reaction. Structural features of 3 and 4 have been analyzed by NMR and X‐ray techniques.     

Synthesis of 4H‐indeno[1,2‐b]thiophenes, 8H‐indeno[2,1‐b]‐thiophenes and 8H‐indeno[2,1‐b]furans having acrylic acid unit

Treatment of methyl propiolate and 2‐(thiophen‐2‐yl)benzaldehyde, 2‐(thiophen‐3‐yl)benzaldehyde or 2‐(furan‐3‐yl)benzaldehyde with tetrabutylammonium iodide/zirconium (IV) chloride or treatment of methyl acrylate and the same aldehydes with 1,4‐diazabicyclo[2,2,2]octane and triethanolamine induce an aldol‐type reaction to furnish Baylis‐Hillman adducts β‐iodo‐α‐(hydroxymethyl)acrylates or α‐(hydroxy‐methyl)acrylates, respectively. These can be used for the preparation of indenothiophenes and indenofurans having acrylic acid unit by intramolecular Friedel‐Crafts reaction with sulfuric acid in tetrachloromethane.     

Convenient synthesis of some new substituted pyrazolyl‐1,3,4‐oxadiazoles and pyrazolyl‐1,2,4‐triazoles

A simple and versatile method for the synthesis of pyrazol‐3‐yl‐1,3,4‐oxadiazole, pyrazol‐3‐yl‐1,2,4‐triazole, (1,5‐diphenylpyrazol‐3‐yl)‐(3,5‐dimethyl‐1‐carbonyl)pyrazole and (1,5‐diphenylpyrazol‐3‐yl)‐(5‐hydroxy‐3‐metheyl‐1‐carbonyl)pyrazole derivatives from 1,5‐diphenylpyrazole‐3‐carboxylic acid hydrazide has been developed.     

An improved synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates

An efficient two steps procedure for the synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates, starting from 2‐chlorobenzoic acids, was developed and in general, moderate to good yields were obtained     

Some nucleophilic substitutions in 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine

In some nucleophilic substitution reactions of 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine, nitrogen (alkylamines, guanidine) and oxygen nucleophiles (alkoxides) underwent substitution of the 2‐cyano group, while sulfur nucleophiles (alkylthiols) underwent substitution of the 3‐nitro group.     

Cyclization of dialkylpropyn‐1‐yl(allyl)(3‐isopropenylpropyn‐2‐yl)ammonium bromides and water‐base cleavage of 2,2‐dialkyl‐5‐methyl‐2,6,7,7a‐tetrahydro‐1h‐isoindolium and 2,2‐dialkyl‐5‐methylisoindolinium bromides

Dialkylpropyn‐1‐yl(or allyl)(3‐isopropenylpropyn‐2‐yl)ammonium bromides under base‐catalyzed condition instantly undergo intramolecular cyclization. The cyclization of dialkylpropyn‐1‐yl(3‐isopropenylpropyn‐2‐yl)ammonium bromides leads to the formation of 2,2‐dialkyl‐5‐methylisoindolinium salts. In case of allyl analogs, instead of the expected 2,2‐dialkyl‐6‐methyl‐3a,4‐dihydroisoindolinium salts their isomeric forms ‐ 2,2‐dialkyl‐5‐methyl‐2,6,7,7a‐tetrahydro‐1H‐isoindolium bromides are obtained. In alkaline medium they are transform into the dihydroisoindolinium salts, the cleavage of which in two directions ‐ 1,2 and 1,6 leads to the mixture of isomeric dialkyl‐1,4‐dimethyl‐ and 2,4‐dimethylbenzyl‐amines. Study of the behavior of 2,2‐dialkyl‐5‐methylisoindolinium salts under conditions of water‐base cleavage showed, that only spiro[5‐methylisoindolyn]morpholinium bromide undergoes 1,2‐elimination, forming 5‐methylisoindoline 2‐vinyl ethyl ester.     

Microwave‐assisted claisen rearrangement. Application to the synthesis of angelicin derivatives

4′‐(Hydroxy, chloro, amino, acetoxy and methoxy)‐methyl‐4,5′‐dimethylangelicins were efficiently and rapidly synthesized via Claisen rearrangement of 4‐methyl‐7‐[4‐(hydroxy, chloro, amino, acetoxy and methoxy)‐but‐2‐ynyloxy]‐coumarins respectively under microwave irradiation. Prominent among the advantages of this new method are operational simplicity, good yields in short reaction times and easy work‐up procedures employed.     

A facile synthesis of pyrazolo[3,4‐D]pyridazines Via the 1,3‐dipolar cycloaddition of 3‐arylsydnones. Synthesis and computational studies of 1‐aryl‐4,5‐dihydro‐1H‐pyrazolo[3,4‐D]pyridazine‐3,6‐diones and their 3,6‐dichloro derivatives.

The synthetic utility of 1,3‐dipolar cycloaddition of DMAD to sydnones has been exploited in the preparation of new 1‐aryl‐4,5‐dihydro‐1H‐pyrazolo[3,4‐d]pyridazine‐3,6‐diones 7a‐j and their aromatic 3,6‐dichloro analogues 8a‐j . The lactam‐lactim tautomerism of compound 7a has been studied by the semi emperical (PM3) and ab initio methods.     

Synthesis and reactions of 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone

3‐Nitrosoimidazo[1,2‐a]pyridine, 3‐nitrosoimidazo[1,2‐a]pyrimidine, 3‐nitrosoquinoxaline, 2‐nitroso‐4H‐benzo[b]thiazine, 2‐nitroso‐4H‐benzo[b]oxazine, isoxazoles, isoxazolo[3,4‐d]pyridazines and pyrrolo[3,4‐d]isoxazole‐4,6‐dione were synthesized from 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone and different reagents. Structures of the newly synthesized compounds were confirmed by elemental analysis and spectral data.     

Synthesis of novel 2‐amino‐6,8‐dithioxopurine derivatives

The synthesis of novel 2‐amino‐9‐alkoxyalkylpurine derivatives with both identical and different sulfur containing substituents at positions 6 and 8 of the purine cycle has been accomplished. The thionation and alkylation of the key intermediate ‐ 2‐[2‐(acetylamino)‐6,8‐dichloro‐9H‐purin‐9‐yl]methoxyethyl acetate or its reactions with thiolates were used. The structures of compounds obtained were confirmed by spectroscopic data and X‐ray diffraction analysis.     

One‐pot synthesis of 2‐aminobenzothiazoles using a new reagent of [bmim]br3 in [bmim]BF4

The one‐pot direct synthesis of 2‐aminobenzothiazoles from phenyl isothiocyanate and amines using a new reagent of 1‐butyl‐3‐methylimidazolium tribromide ([Bmim]Br₃) in ionic liquid 1‐butyl‐3‐methylimidazolium tetraflouoroborate ([Bmim]BF₄) is described.     

Reactivity of 3‐amino‐3H‐quinazolin‐4‐one derivatives towards some electrophilic and nucleophilic reagents and using of the products in the building of some interesting heterocycles as anticancer agent

The chemical reactivity of N‐[1‐(3‐amino‐6,8‐dibromo‐4‐oxo‐3,4‐dihydro‐quinazolin‐2‐yl)‐2‐(2‐chlorophenyl)‐vinyl]benzamide ( 3 ) towards electrophilic and nucleophilic reagents have been reported. Structures of the products 3‐24 have been confirmed by elemental analysis and spectral data (IR, ¹H‐NMR, ¹³C and MS). The bioassay indicates that some of the prepared compounds have a good selective anticancer activity.     

Ready access to 7,8‐dihydro‐ and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐ones from simple pyridine precursors

Short pathways are described for the synthesis of a representative example of each of the 7,8‐dihydro‐and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐one ring systems from simple pyridine precursors. An attempted synthesis of the related 4,6‐dihydro‐1,6‐naphthyridin‐5(1H)‐one ring system from a common intermediate was unsuccessful.     

New fragmentation of 2‐isoxazoline‐5‐carboxylic acid chlorides

A novel base promoted degradation of 3‐aryl‐2‐isoxazoline‐5‐carboxylic acid chlorides to aryl nitriles has been discovered.     

One‐pot three‐component synthesis of 2‐substituted 4‐aminoquinazolines

A facile and rapid synthesis of the title compounds via one‐pot reaction of 2‐aminobenzonitrile, orthoesters and ammonium acetate under solvent‐free and microwave condition is described.     

Synthesis and antimicrobial activity of new benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones

New benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones are synthesized in which benzofuran is coupled with 1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones through ‐CONH‐ and ‐COCH₂‐ bridges, respectively. The antimicrobial activity of these compounds is reported.     

A mechanistic approach to photochemical behavior of 4‐anisyl‐4‐methyl‐2,6‐diphenyl‐4H‐thiopyran‐1,1‐dioxide

Photoisomerization of 4‐anisyl‐4‐methyl‐2,6‐diphenyl‐4H‐thiopyran‐1,1‐dioxide is described in the presence of a sensitizer and new mechanistic features are proposed. The relative molar ratios of the stereoselective photoproducts compared in the presence and the absence of sensitizer in different concentrations of the starting material using hplc. The results observed are discussed on the basis of a triplet excited state thiadi‐π‐methane rearrangement.     

1,8‐Diazafloren‐9‐one with alkyl and aryl isocyanides in the presence of acetylenic esters: A facile synthesis of γ‐spiroiminolactones

The 1:1 intermediate generated by the addition of alkyl and aryl isocyanides to dialkyl acetylenedicarboxylate is trapped by 1,8‐diazafloren‐9‐one to yield iminolactones in good yields.     

Convenient synthesis of N‐substituted 1‐alkyl and 1‐aryl‐3‐aminoisoquinolines

Cyclocondensation of 2‐acylphenylacetonitriles 1 with amines affords 1‐substituted 3‐aminoisoquinolines 2 in good yields.     

Transformation of 4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehydes into pyrazolo[3,4‐B]pyridines

Reaction of 6‐methyl‐4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehyde 1 with 5‐amino‐3‐methyl‐1‐phenylpyrazole 2 in alcoholic reaction media in the presence of 4‐toluenesulfonic acid as catalyst afforded 5‐(2‐hydroxy‐5‐methylbenzoyl)‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine 3 and 2‐methoxy‐6‐methyl‐3‐(3‐methyl‐1‐phenylpyrazol‐5‐ylaminomethylene)chroman‐4‐one 7 . We explain the mechanism of formation of both products on the basis of kinetic study of individual reaction steps.