An efficient synthesis of highly substituted pyrrole and bis pyrrole derivatives

An efficient synthesis of highly substituted pyrrole and bis pyrrole derivatives is reported.     

Synthesis of substituted 1,2,4‐oxadiazoles from substituted acid chlorides and amidoximes under mild conditions

Substituted amidoximes have been synthesized, isolated and converted into substituted oxadiazoles as a novel heterocyclic compounds under mild conditions in good to excellent yield.     

Facile synthesis of 6‐aryl‐5H‐8‐oxa‐4b, 7‐diaza‐benzo[a]azulen‐9‐one derivatives,new tricyclic heterocycles

8‐Oxa‐4b,7‐diaza‐benzo[a]azulene‐9‐one system, a new tricyclic heterocyclic framework is designed through a simple and convenient synthetic sequence. Its 6‐aryl derivatives are synthesized starting from ethyl indole‐2‐carboxylate. Reaction of differently substituted phenacyl bromides with ethyl indole‐2‐carboxylate, treatment of the resultant N‐substituted indole‐2‐carboxylates with hydroxylamine hydrochloride to provide corresponding oximes, subsequent ester hydrolysis followed by dehydrative cyclisation furnished the desired compounds 5 a‐g .     

Synthesis of some novel 2‐substituted‐N‐aryl‐benzoxazole‐5‐carboxamides using cobalt dipyridine dichloride as a catalyst

An efficient synthesis of some novel 2‐substituted‐N‐aryl‐benzoxazole‐5‐carboxamides from 2‐substituted — 5‐carbomethoxy benzoxazole on treatment with different substituted anilines promoted by cobalt dipyridine dichloride as a catalyst is described. This new approach has the advantage of excellent yields (90%) and short reaction times 1‐2 h.     

Polystyrene‐supported AICI3: A highly active and reusable heterogeneous catalyst for the one‐pot synthesis of dihydropyrimidinones

An environmentally benign Biginelli protocol for the one‐pot synthesis of substituted 3,4‐dihydropyrimidin‐2(1H)‐ones using polystyrene supported aluminium chloride as catalyst has been achieved. This polymeric catalyst is stable and can be easily recovered and reused without obvious change in their efficiency.     

A new method for the synthesis of bicyclic pyran acetals

cis‐Fused bicyclic acetals were obtained from the unusual cyclization reaction between diols and dihydropyran. Furothiopyran, substituted pyranopyrans, and pyranooxepine and pyranobenzoxepine compounds were obtained with high diastereoselectivity and cis‐diastereomers were obtained in high yields.     

Synthesis of new terpolymers with heterocyclic pendant groups

Chemical modifications of polyacrylonitrile (PAN), an inexpensive and commercial homopolymer, to obtain terpolymers containing 1,2,4 or 1,3,4 oxadiazolic pendant groups are described. These new materials are physically and spectroscopically characterized.     

Synthesis of new imidazole derivatives

The derivatives of 1‐propyl‐ and 1‐butyl‐ of 2‐methyl‐5‐nitroimidazole containing phenylpiperazine, m‐chloro‐ and o‐methoxyphenylpiperazine attached at the end of alkyl chain were synthesed. For the obtained new compounds, the biological activity was predicted using the computer program PASS.     

A convenient synthesis of 5‐alkylthio‐3,4‐diarylisoxazoles by palladium‐catalyzed coupling reactions

Palladium‐catalyzed coupling reaction was found effective for rapid access to pharmacologically interesting 3,4‐diarylisoxazoles derivatives as selective COX‐2 inhibitors. Thus, the coupling reaction between 5‐alkylthio‐3‐aryl‐4‐iodoisoxazoles and arylboronic acids afforded the target 5‐alkylthio‐3,4‐diarylisoxazoles in good yields.     

1,3‐dipolar cycloadditions. Part XII ‐ selective cycloaddition route to 4‐nitroisoxazolidine ring systems

Cycloadditions of C,N‐diarylnitrones to β‐nitrostyrenes occurred to yield two diastereoisomeric cycloadducts, the 3,4‐trans‐4,5‐trans substituted isoxazolidine derivatives being formed selectively as the major products. These were characterised by spectroscopic and X‐ray data. Conformational studies were carried out by X‐ray crystallography and Molecular Modelling.