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 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.     

Isothiazolo[5,4‐d]isoxazole S,S‐dioxides and pyrazolo [3,4‐d]‐isothiazole S,S‐dioxides through cycloaddition reaction on 3‐benzylaminoisothiazole S,S‐dioxides

By reacting 4,5‐unsubstituted isothiazole dioxides with diazoalkanes and nitrile oxides bicyclic pyrazolo[3,4‐d]isothiazole and isothiazolo[5,4‐d]isoxazole S,S‐dioxides were obtained in good yield through a regioselective cycloaddition reaction. Through cycloaddition reaction of 3‐benzylamino‐4‐bromo‐isothiazole S,S‐dioxide labile cycloadducts were formed that underwent in situ dehydrobromination affording the corresponding aromatized compounds.     

Aromatization of 1,4‐dihydropyridines in the presence of methanesulfonic acid/NaNO2/wet SiO2 under both heterogeneous and solvent free conditions

A combination of methanesulfonic acid and sodium nitrite in the presence of wet SiO₂ was used as an effective oxidizing agent for the oxidation of 1,4‐dihydropyridines to the corresponding pyridine derivatives under mild and heterogeneous conditions in excellent yields.     

An efficient one‐pot synthesis of n‐carboxymethylacridine‐1,8‐dione derivatives under microwave irradiation

A series of N‐carboxymethylacridine‐1,8‐dione derivatives were synthesized by one‐pot reaction of aldehyde, dimedone and glycine in glycol under microwave irradiation without catalyst with excellent yields (78‐92%) and short reaction time (4‐8min). And the reaction was not only suitable for aromatic monoaldehyde, but also aromatic dialdehyde.     

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 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.     

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.     

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.     

Facile synthesis of pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione dimer

Efficient synthesis of biological important pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione dimer linked through the C‐2 positions by fumarate group is described.     

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.     

Cyclocondensation reactions of heterocyclic carbonyl compounds XII. The double course of cyclization of 3‐(2‐aminobenzyl)‐1,2‐dihydro‐quinoxaline‐2‐one

The cyclocondensation reaction of compound 1 in boiling hydrochloric acid had an unexpected course. Instead of supposed 5,11‐dihydro‐quinoxalino[2,3‐b]quinoline 6a , 2‐(indol‐2‐yl)‐benzimidazole 4 was isolated as the major product.     

A practical synthesis of 5‐(4′‐methylbiphenyl‐2‐yl)‐1H‐tetrazole

Practical synthesis of 5‐(4′‐methylbiphenyl‐2‐yl)‐1H‐tetrazole, key intermediate in several angiotensin II receptor antagonists from 2‐fluorobenzonitrile in excellent yields and very high purity is described.     

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.     

Preparation of 6‐azaoxindole (6‐azaindol‐2(3H)‐one) and substituted derivatives

A general synthesis of 6‐azaoxindoles, substituted in the 3‐ and 5‐position, has been developed starting from 4‐methoxycarbomethyl‐3‐nitropyridine, via hydrogenation of the nitro group and cyclisation of the resulting 3‐amino‐4‐methoxycarbomethyl‐pyridine.     

An efficient synthesis of pharmacologically active derivatives of 1,3,4‐oxadiazoles

A simple and environmental friendly microwave irradiation method is devised for the synthesis of derivatives of 1,3,4‐oxadiazoles viz., 6a‐e and 7h‐q in 75–90% yield. Structures of the newly synthesised compounds were confirmed by physical, analytical and spectral (ir, ¹H and ¹³C nmr and ms) data and screened for antiinflammatory, anticonvulsant, antidiuretic and antihaemostatic activities. Some of the compounds have shown potent activities.     

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.     

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 .     

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.