Synthesis of 3‐arylazo‐6‐oxopyridazin‐5‐carbonitriles: A versatile precursor for condensed arylazopyridazin‐6‐ones

1‐[2‐Phenyl‐1‐diazenyl]‐1‐[2‐phenylhydrazono]acetone or 1‐[‐2‐(4‐methylphenyl)‐1‐diazenyl]‐1‐[‐2‐(4‐methylphenyl)hydrazono]‐butan‐2‐one were produced via coupling the (E) 2‐oxopropanal‐1‐phenyl‐hydrazone or (E) 2‐oxobutanal‐1‐(4‐methylphenyl)hydrazone with aromatic diazonium salts. These formazanes condensed readily with ethyl cyanoacetate to yield 5‐methyl‐3‐oxo‐2‐phenyl‐6‐phenylazo‐2,3‐dihydropyridazine‐4‐carbonitrile compound ( 9a ), 5‐ethyl‐3‐oxo‐2‐p‐tolyl‐6‐p‐tolylazo‐2,3‐dihydro‐pyridazine‐4‐carbonitrile and/or 5‐ethyl‐3‐oxo‐2,6‐di‐p‐tolyl‐2,3‐dihydropyridazine‐4‐carbonitrile that reacted with sulphur in presence of piperidine to yield the aminothienopyridazinones. The latter reacted with electron poor olefins and acetylenes to yield aminophthalazines. Compound ( 9a ) reacted also with benzylidenemalononitrile to yield the arylazophthalazinone.     

FeCI3‐promoted [3+3] cycloaddition: Efficient preparation of 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives

A facile approach was developed on assembly of the 2‐pyridone nucleus by ferric chloride promoted [3+3] cycloaddition in propionic acid. The tandem process involves cyclization of Michael adduct followed by aromatization. Thus, different substituted 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives were prepared in good yields from various enones with malonamic ester and malonamide, respectively     

A facile one‐pot synthesis of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives without catalyst

A series of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives were synthesized by one‐pot condensation of aromatic aldehyde, a‐naphthylamine and malononitrile in ethanol without catalyst. This multicomponent reaction has the notable advantages of short route, high yield and convenient operation.     

Synthesis of substituted 3‐pyrrolidinecarbonitriles

Cyclopropanes substituted at the same ring carbon by two electron‐withdrawing groups such as alkoxycarbonyl or cyano group react with the primary arylamines via a ring‐opening reaction and ensuing intramolecular cyclization to form substituted pyrrolidines.     

Green multicomponent synthesis of 1,2‐dihydro‐pyrimido[1,2‐a]‐benzimidazole‐3‐carbonitrile

1,2‐dihydro‐pyrimido[1,2‐a]benzimidazole‐3‐carbonitrile derivatives were synthesized via the three‐component reaction of aldehyde, malonodinitrile and 2‐aminobenzimidazole in water under microwave irradiation. The new protocol has the advantages of excellent yield, low cost, reduced environment impact, wide scope and convenient procedure.     

Synthesis of 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinolin‐5‐ol derivatives

This paper describes the synthesis of 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinolin‐5‐ol derivatives ( 3a‐h ) and 4‐amino‐5,6,7,8‐tetrahydrothieno[2,3‐b]quinoline ( 8a ) in good yield by three‐step procedures starting from 2‐aminothiophene‐3‐carbonitrile and 5‐substituted cyclohexane‐1,3‐dione.     

Synthesis of some 2‐oxo and 2‐thioxo substituted pyrimidines using solvent‐free conditions

A series of oxo‐ and thioxopyrimidines 4 ( a‐m ) were synthesized by one‐pot three components cyclocondensation reaction of β‐ketoester, aldehyde and urea/thiourea using benzyltriethylammonium chloride as a catalyst under solvent‐free conditions. The yields of products following recrystallization from ethanol were of the order of 65‐87%. IR and ¹HNMR spectroscopy and elemental analysis were used for identification of these compounds.     

Application of the acetate of baylis‐hillman adducts of salicylaldehydes in the synthesis of methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates

A simple synthesis of several methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates from Baylis‐Hillman adducts of O‐benzyl protected 2‐hydroxybenzadehydes has been described through the acetylation, cyanation, debenzylation, as well as acid assisted Pinner cyclization.     

Synthesis of an 4‐oxo‐1,4‐dihydropyridinomethylidene substituted 2‐indolinone

The (Z)‐3‐substituted 2‐indolinone 6 was prepared using the aldehydes 4 and 8 unknown up to now and 2‐indolinone.     

One‐pot synthesis of new 3‐substituted coumarins by tandem reactions

The synthesis of new 3‐substituted coumarins appended to imidazolium, pyridinium, 3‐dimethylamino pyridinium, 3‐chloro pyridinium and 3‐bromo pyridinium salts is reported. These salts were prepared by tandem reactions, followed by quantitative anionic metathesis. The structure of these new 3‐substituted coumarins was established by NMR (¹H, ¹³C) and high‐resolution mass spectrometry.     

Homogeneous,unimolecular gas‐phase elimination kinetics of ethyl esters of glyoxylic, 2‐oxo‐propanoic,and 3‐methyl‐2‐oxo‐butanoic acids

The rates of elimination of several ethyl esters of 2‐oxo‐carboxylic acid were determined in a seasoned static reaction vessel over the temperature range 350–430°C and pressure range 33–240 Torr. The reactions, in the presence of a free‐radical inhibitor, are homogeneous, unimolecular, and follow a first‐order rate law. The overall and partial rate coefficients are expressed by the Arrhenius equation. Ethyl glyoxalate Ethyl 2‐oxo‐propionate Ethyl 3‐methyl‐2‐oxo‐butyrate The mechanisms of these elimination reactions are described in terms of concerted cyclic transition state structures. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 268–275, 2007     

Synthesis and antimicrobial activity of some new N‐(substituted phenyl)‐N′‐[2,3‐dihydro‐2‐oxido‐3‐(4′‐fluorophenyl)‐1H‐(1,3,2)benzoxazaphosphorin 2‐yl]ureas

Substituted benzoxazaphosphorin 2‐yl ureas were synthesized by reacting 2‐(4‐fluoro‐phenylamino)‐methylphenol (4) with different carbamidophosphoric acid dichlorides (3) in the presence of triethylamine in dry toluene at 45‐50 °C and characterized by spectral data. These compounds were found to possess good antimicrobial activity.     

Convenient way to 5‐substituted 4‐amino‐2,3‐dihydro‐4H‐1,2,4‐triazole‐3‐thiones

Various 4‐amino‐2,3‐dihydro‐4H‐triazoles with aromatic, aliphatic and heterocyclic substituents at the C(5) position were synthesized from corresponding esters and thiocarbohydrazide. This method allows the synthesis these heterocycles in a short time and at reduced expenses.