Deoxygenation of pyridine N‐oxides with dimethylthiocarbamoyl chloride

Treatment of pyridine N‐oxides with dimethylthiocarbamoyl chloride in boiling acetonitrile effects chemoselective deoxygenation to pyridines.     

Regioselective synthesis of heterocyclic scaffold by aryl radical cyclization

Regioselective synthesis of a number of coumarin‐annulated pentacyclic heterocycles have been achieved by tri‐n‐butyltin hydride‐mediated aryl radical cyclization. The products are formed as a mixture of cis‐ and trans‐ forms which were successfully separated by careful silica gel flash chromatography.     

A facile three‐components,one‐pot synthesis of pyrimido[4,5‐d]pyrimidine‐2,5‐dione derivatives under microwave‐assisted conditions

Pyrimido[4,5‐d]pyrimidine‐2,5‐dione derivatives have been synthesized in high yields in a novel, onepot, and efficient process by condensation of 6‐amino‐3‐methyl‐2‐(methylthio)pyrimidin‐4(3H)‐one, aldehydes and urea under microwave‐assisted conditions.     

Synthesis and reactions of some new allyl furobenzopyranone derivatives

Reaction of visnaginone 1 with allyl bromide gave O‐allyl visnaginone 2 which underwent Claisen rearrangement to yield 7‐allylbenzofuran derivative 3 . Reaction of 3 with different aromatic aldehydes gave the corresponding 5‐cinnamoylbenzofuran derivatives 4a‐d . Condensation of the latter chalcones 4a,c,d with hydrazine hydrate and phenylhydrazine provided, the corresponding pyrazoline derivatives 7a‐f . Claisen condensation of compound 3 with ethyl acetate and diethyl carbonate afforded Claisen adducts 8 and 12 which easily cyclized to 9 and 13 , which are endowed with interesting biological properties.     

Ketene dithioacetals‐source for different heterocycles

Some pyrazoline, isoxazoline and pyrimidine derivatives were synthesized from ketene dithioacetals using appropriate nucleophiles.     

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     

A mild and highly efficient method for the synthesis of 5‐aryl‐(N‐phenyl‐)6H‐1,3,4‐thiadiazin‐2‐aminium salts using reusable heterogeneous catalysts

5‐Aryl‐6H‐1,3,4‐thiadiazin‐2‐aminium and 5‐aryl‐N‐phenyl‐6H‐1,3,4‐thiadiazin‐2‐aminium salts have efficiently been synthesized from the reaction of thiosemicarbazide and α‐haloketones in acetonitrile at room temperature using i) silica supported sodium hydrogen sulfate and ii) silica sulfuric acid as reusable heterogeneous catalysts. The experimental procedure is simple and the products are obtained in high yields.     

1‐Arylsulfonyl‐2‐styrylsulfonylthenes — source for a new class of bis heterocycles

New and novel sulfone linked bis heterocycles_ bis pyrroles and pyrrolyl pyrazolines are prepared from 1‐arylsulfonyl‐2‐styrylsulfonylethenes by 1,3‐dipolar cycloaddition methodology.     

Synthesis,structures of some unsymmetrical 3,6‐disubstituted‐1,2,4,5‐tetrazines

A series of new unsymmetrical 3‐phenyl‐6‐benzyl‐1,2,4,5‐tetrazine derivatives 10a‐i were synthesized and characterized by IR, NMR, MS, and element analysis. The structures of 4a, 10c, 10d and 10h were analyzed by X‐ray crystallography, which had intermolecular C‐H‐N, C‐H‐Cl, C‐H‐II and II‐II interactions.     

Dodecyloxy‐substituted 2,4,6‐tris(styryl)pyridines

(E,E,E)‐2,4,6‐Tris(styryl)pyridines 2a‐c with 3, 6 or 9 dodecyloxy substituents were prepared by the highly stereoselective condensation reaction of collidine ( 8 ) and the corresponding phenyl‐(1‐phenyl‐methylidene)amines 7a‐c (Siegrist reaction). In contrast to the corresponding compounds with a benzene or a 1,3,5‐triazine core, 2a‐c do not show any hints for the formation of thermotropic liquid crystals. The major application of such star‐shaped systems is in the field of nonlinear optics.     

Synthesis of multi‐substituted dibenzo[b,d]furan

The synthesis of multi‐substituted dibenzo[b,d]furan derivatives 7a‐b and 11a‐b from readily available starting materials is described. These compounds are important intermediates for synthesis of molecules having wide therapeutic applications.     

Synthesis of a novel class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones under solvent‐free and catalyst‐free conditions

A solvent‐ and catalyst‐free one‐pot three‐component condensation reaction approach was developed for the synthesis of a new class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones in relatively good yields.     

Synthesis of new spiro‐[isothiochromene‐3,5′‐isoxazolidin]‐4(1H)‐ones

A series of seven new 2′,3′,4′‐substituted spiro[isothiochromene‐3,5′‐isoxazolidin]‐4(1H)‐ones ( 7‐13 ) has been prepared in the reaction of benzylidene(phenyl)azane oxide ( 5 ) or benzylidene(methyl)azane oxide ( 6 ) with (3Z)‐3‐(4‐substituted‐benzylidene)‐1H‐isothio‐ chromen‐4(3H)‐one ( 1‐4 ). The reaction occurs by a 1,3‐dipolar cycloaddition mechanism that leads to the regiospecific formation of various spiroisoxazolidines ( 7‐13 ).     

Synthesis and fluorescence of 2h‐pyrone derivatives for organic light‐emitting diodes (OLED)

2H‐Pyrone derivatives were synthesized through the reaction of aryl acetyl compounds with ketene dithioacetals in the presence of sodium hydroxide, and they showed very strong fluorescence in the solid state. The light‐emitting region of these 2H‐pyrones is 447‐630 nm in the solid states.