A general synthesis of 8‐hydroxy‐6‐substituted‐1,7‐naphthyridines

A general method for the synthesis of 8‐hydroxy‐6‐substituted‐1,7‐naphthyridines is described using acylation of the dianion derived from tert‐butylamide 1 , followed by cyclization of the resulting intermediate ketones 2 with ammonium acetate.     

Synthesis of novel bis‐condensed heterocyclic ring assembly systems

The novel bis‐condensed heterocyclic systems with ring assemblies based on peripheral barbituric acid rings and central pyran, pyridine and thiine rings have been generated by the reaction of terephthalaldehyde and isophthalaldehyde with barbituric acid for comparison with the analogous systems generated with said dialdehydes and 1,3‐cyclohexanedione.     

One‐pot synthesis of hexahydroquinolines Via a four‐component cyclocondensation under microwave irradiation in solvent free conditions: A green chemistry strategy

Four‐component cyclocondensation of aromatic aldehydes, malononitrile, dimedone and ammonium acetate proceeds under microwave irradiation in solvent free conditions to give highly functionalized hexahydroquinolines in excellent 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.     

A novel synthesis of 5‐aryl‐3‐phenylpyrazole from 2‐aryl‐3‐benzoyl‐1,1‐cyclopropanedicarbonitrile and hydrazine

A new process for synthesis of 5‐aryl‐3‐phenylpyrazole is achieved. The regioselective ring‐opening reaction of 2‐aryl‐3‐benzoyl‐1,1‐cyclopropanedicarbonitrile with hydrazine plays a crucial role in the described process.     

Synthetic study for two 2H‐chromenic acids, 8‐chlorocannabiorcichromenic acid and mycochromenic acid

Two 2H‐chromenes having a fully substituted benzene ring, 8‐chlorocannabiorcichromene ( 1 ) and mycochromenic acid ( 2 ), were synthesized by a condensation of salicylaldehydes with isopropylidenemalonate or the thermal cyclization of corresponding propargyl ethers.     

Microwave induced synthesis of the thiazolidine‐2,4‐dione motif and the efficient solvent free‐solid phase parallel syntheses of 5‐benzylidene‐thiazolidine‐2,4‐dione and 5‐benzylidene‐2‐thioxo‐thiazolidine‐4‐one compounds

Novel microwave induced method for the synthesis of thiazolidine‐2,4‐dione motif under solvent phase conditions is developed. Further we report an efficient, microwave assisted method for the parallel syntheses of biologically important 5‐benzylidene‐thiazolidine‐2,4‐dione and 5‐benzylidene‐2‐thioxothiazolidine‐4‐one compounds under solid‐phase and solvent‐free conditions. A comparative study between the developed microwave methods and the conventional methods is described. We have also illustrated the possible mechanism behind to address the reason why piperidine, acetic acid and silica gel enhanced the Knoevenagel condensation reaction.     

Lithiation of N‐protected‐dihydro‐1,4‐benzoxaziness

Lithiation of N‐protected‐2,3‐dihydro‐1,4‐benzoxazines is described. Lithiation of N‐(tert‐butoxycarbonyl)‐2,3‐dihydro‐1,4‐benzoxazine ( 1 ) with BuLi/TMEDA occurred in the α‐position to nitrogen on the heterocyclic ring, leading to the unexpected ring‐opened product 3 . On the other hand, lithiation of N‐methyl‐2,3‐dihydro‐1,4‐benzoxazine ( 4 ) took place at the oxygen‐adjacent ortho‐position of the aromatic ring.     

Homolytic alkylation of some 3,4‐quinolinediyl bis‐sulfides under minisci reaction conditions

Reaction of hydrogen sulfate of 3,4‐quinolinediyl bis‐sulfides 1a , 2a , 3a , and 4a with isopropyl and cyclohexyl radicals formed from alkyl iodide/hydrogen peroxide/DMSO/Fe⁺⁺ salt system took place at α‐quinolinyl position and led to the respective mono‐ and dialkyl derivatives 1b‐e , 2b‐e , 3b,c , and 4b,c . Action of sodium methoxide towards isopropyl derivatives 1b,c and 2b,c caused the 1,4‐dithiin ring opening to form (after S‐methylation) derivatives of 3,4′‐ and 3,3′‐diquinolinyl sulfides 6a,b and 7a,b .     

New access to thiazolo[4,5‐d]pyrimidine derivativess

4‐Amino‐5‐bromo‐2‐substituted‐aminopyrimidines are readily obtained from the newly prepared 5‐bromo‐2,4‐dichloro‐6‐methylpyrimidine by sequential treatment with ethanolic ammonia and secondary amines. These compounds were successfully reacted with various isothiocyanates in the presence of sodamide in DMF to form the new thiazolo[4,5‐d] pyrimidine derivatives.     

Reactions of cephalosporin sulfones 3. Synthesis of 2‐phenylhydrazonocephem‐sulfones. A new potential entry to 2‐aminocephems

Reaction of cephem sulfones 1a‐e with aryldiazonium salts gives the 2‐azo compounds which immediately rearrange into the corresponding 2‐hydrazono derivatives 2a‐e .     

Cyclization of 2‐benzoylamino‐N‐methyl‐thiobenzamides to 3‐methyl‐2‐phenylquinazolin‐4‐thiones

Acylation of 2‐amino‐N‐methyl‐thiobenzamide with substituted benzoyl chlorides has been used to synthesize the corresponding 2‐benzoylamino‐N‐methylthiobenzamides. Subsequent sodium methoxide‐catalyzed ring closure gives the corresponding 3‐methyl‐2‐phenylquinazoline‐4‐thiones. These compounds were characterized by means of their ¹H‐ and ¹²C‐NMR spectra. The kinetics of the cyclization reaction has been followed with UV‐VIS spectroscopy at 100 °C in methanolic solutions of sodium methoxide.     

Synthesis of 2‐phenylquinolin‐4‐amines substituted with diverse amino and aminoalkyl groups

Facile synthetic approaches to 2‐phenylquinolin‐4‐amines containing an aminoalkyl group at N⁴ of the quinolin‐4‐amine and amino or aminoalkyl groups at the phenyl moiety are presented.     

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.     

New synthesis,x‐ray structural determination,conformational analysis and anomeric effect study of 3,7‐di (3‐nitrophenyl)‐1,5‐dioxa‐3,7‐diazacyclooctane

3,7‐Di(3‐nitrophenyl)‐1,5‐dioxa‐3,7‐diazacyclooctane was prepared from 3‐nitroaniline and formaldehyde in acetonitrile. Conformational behavior of ring inversion of the molecule was studied so it prefers a crown conformation. The evaluated ΔG^* was approximately 58.0 ± 1.0 kJ/mole. The X‐ray structure determination of the compound shows a crown conformation, in line with two‐anomeric effect in N‐C‐O moiety.     

Synthesis of 1,3‐oxazole and benzimidazole pendant groups from polyacrylonitrile hydrolysis products

New terpolymers containing heterocyclic pendant groups, such as 1,3 oxazole and benzimidazole are obtained by hydrolysis of polyacrylonitrile (PAN). These materials are spectroscopically characterized and their solubility, viscosity and thermal behavior are analyzed.     

I2‐catalyzed reactions of schiff base and alkyl aldehyde towards benzo[f]quinoline derivatives

A mild, efficient, and general method for the synthesis of benzo[f]quinoline derivatives via a molecular iodine‐catalyzed reaction of Schiff base with alkyl aldehydes has been described. The structure of 3o was confirmed by X‐ray diffraction study.