Studies with pyridazines and condensed pyridazines: Routes for synthesis of 3‐amino‐5‐aryl‐2,5‐dihydro‐pyridazine, 10aH‐pyridazino[1,6‐a]quinazoline and thieno[3,4‐d]pyridazinone

Novel routes to 3‐aminopyridazines, 10aH‐pyridazino[1,6‐a]quinazoline and, thieno[3,4‐d]pyridazine utilizing the reaction of 2‐oxobutanal‐1‐arylhydrazones 3a,b with α,β‐unsaturated nitriles are described. Condensation of 3 with ethyl cyanoacetate afforded pyridazinones that reacted with sulphur yielding thienopyradazinone 10 . Reaction of 10 with maleic anhydride and acrylonitrile afforded products of addition and hydrogen sulphide elimination. On other hand reacting 10 with enaminone and ethyl propionate afforded the product of addition of the amino function to activated double bond.     

Studies with S‐alkylpyrimidine: New route for the synthesis derivatives of isoxazol,pyrazolo[1,5‐a]pyrimidine,pyridazine, pyridine,thieno[2,3‐b]pyridine and thiophene of potential anti‐HIV

Derivatives of thiophene, thieno[2,3‐b]pyridine, pyridine, isoxazol, pyrazolo[1,5‐a]pyridine, pyridazine linked with s‐pyrimidine derivative have been synthesized and tested for antimicrobial and antifungal activities. The structure of the newly synthesized compounds have been established on the basis of their analytical and spectral data.     

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.     

An efficient synthesis of pyrazolo[3,4‐b]pyrrolo[2,3‐d]pyridines from 5‐aminopyrazoles and cyclic β‐keto ester

5‐Chloroethylpyrazolo[3,4‐b]pyridines were synthesized by condensation of 5‐aminopyrazoles with α‐acetyl γ‐butyrolactone followed by cyclization treating with phosphorous oxychloride. 5‐Chloroethyl‐pyrazolo[3,4‐b]pyridines, thus obtained, were then converted to the corresponded tricyclic pyrazolo[3,4‐b]‐pyrrolo[2,3‐d]pyridines by treating with some primary amines.     

A rapid and efficient method for synthesis of pyrimido[1,2‐a]‐benzimidazole derivatives under microwave irradiation

A rapid and efficient method for synthesis pyrimido[1,2‐a]benzimidazole derivatives from readily available starting materials is accomplished under microwave irradiation. This method has the advantages of short reaction time, operational simplicity, increased safety for small‐scale high‐speed synthesis, and minimal environment impact.     

A green and efficient synthesis of furo[3,4‐e]pyrazolo[3,4‐b]‐pyridine derivatives in water under microwave irradiation without catalyst

A series of furo[3,4‐e]pyrazolo[3,4‐b]pyridine analogues of podophylloxin were synthesized via three‐component reactions of aldehydes, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine and tetronic acid in water under microwave irradiation without catalyst. This efficient synthesis not only offers an economical and green synthetic strategy to this class of significant compounds but also enriches the investigations on microwave‐assisted synthesis in water.     

Synthesis of new chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines

The total synthesis of chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines from easily prepared 4‐methoxy‐1‐nitro‐9H‐xanthen‐9‐one is reported. These compounds, in which a 1,3‐diazine ring is fused to the xanthene scaffold, were obtained with good overall yields in very few steps.     

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.     

Diverse reactivity of α‐carbanions derived from alkylidenephosphoranes toward 2‐(1λ5‐diazynylidene)‐1H‐indene‐1,3‐(2H)dione. General approach to conjugated oxadiazines,pyridazines and spiro[3]pyrazoles

Different types of phosphonium carbanions were applied to 2‐diazonio‐1,3‐dioxo‐2,3‐dihydro‐1H‐inden‐2‐ide ( 1 ) in order to synthesize a number of condensed and fused N‐heterocycles. When 1 was treated with cyanomethyltriphenylphosphonium chloride oxadiazine‐, and pyridazine derivatives were obtained whereas bis‐indanylidene derivatives resulted from the reaction of 1 with methyl_ and ethyltriphenylphosphonium bromides. On the other hand, a series of substituted and unsubstituted spiro[3′]pyrazoles were obtained from the di azo substrate when reacted with vinyl_and allyltriphenylphosphonium bromides.     

An Efficient synthesis of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives via multicomponent reactions in ionic liquid

A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.