Synthesis of some oxazolyl ‐ pyrazolyl; 1,4‐Dihydropyridinyl‐pyrazolyl and 1,2,3,4‐tetrahydro pyrimidinyl‐pyrazolyl coumarins

Various 3‐[1‐phenyl‐4‐(2‐substituted‐5‐oxo‐oxazol‐4‐ylidenemethyl) pyrazol‐3‐yl] coumarins 4a‐f ; 3‐[1‐phenyl‐4‐(2,6‐dimethyl‐3,5‐disubstituted‐1,4‐dihydropyridin‐4‐yl) pyrazol‐3‐yl] coumarins 5a‐f and 3‐[1‐phenyl‐4‐(6‐methyl‐5‐substituted‐2‐oxo‐1,2,3,4‐tetrahydropyrimidin‐4‐yl) pyrazol‐3‐yl] coumarins 6a‐f have been synthesized utilizing Erlenmyer‐Plochl reaction, Hantzsch reaction and Biginelli reaction respectively using 3‐(1‐phenyl‐4‐formyl‐pyrazol‐3‐yl) coumarins 3a‐c as a starting material.     

Synthesis and characterization of a novel heterocycle: 1‐Substituted‐4‐arylazamethylene‐6‐arylpyrazolo[5,4‐d]‐1,3‐oxazine

A series of novel heterocycles 1‐aryl‐ or alkyl‐substituted‐4‐arylazamethylene‐6‐arylpyrazolo[5,4‐d]‐1,3‐oxazines were synthesized from the acylation of (5‐amino‐1‐substituted‐pyrazol‐4‐yl)‐N‐carboxamide in 63‐89% isolated yields at room temperature within 12 hours. The structure was confirmed by X‐ray crystal analysis.     

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.     

Progress in the chemistry of 4‐ thiazolidinones

This review article includes a recent development in the chemistry of 4‐thiazolidinones. Structure, basicity, synthetic aspects, reactions, and applications were also reported.     

New one‐ pot synthesis of pyrazolo[3,4‐c]pyridazine and isoxazolo‐[5,4‐b]pyridine derivatives from potassium cyanoacetahydroxamate

The reaction of potassium cyanoacetohydroxamate 1 with ethyl 2‐aryl‐hydrazono‐3‐oxobutyrates 2 gave the unexpected pyrazolo[3,4‐c]pyridazines 7 and isoxazolo[5,4‐b]pyridines 10 via a one‐pot reaction. A mechanistic proof is suggested to account for the products.     

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.     

Synthesis and herbicidal activity of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives

A series of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives were designed and synthesized. The structures of all the title compounds were confirmed by ¹H NMR and elementary analysis. These compounds were screened for herbicidal activity against rape and barnyard grass. Compound B13 exhibited moderate herbicidal activity.     

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 and antimalarial activity of 7‐benzylamino‐1‐isoquinolinamines

Computer modelling suggests that 7‐benzylamino‐1‐isoquinolinamines should mediate antimalarial effects by a mechanism distinct from that employed by existing antimalarial drugs. A series of these compounds was prepared in seven synthetic steps, via reductive amination of 1,7‐isoquinolinediamine. In vitro efficacy testing of the novel compounds against Plasmodium falciparum revealed them to be potent antimalarial agents.     

A convenient synthesis of novel 1,3,4‐triaryl‐3,4‐dihydropyrimidin‐2(1H)‐ones by cyclization of aromatic isocyanates with β‐arylamino‐1‐phenylpropan‐1‐ones

A simple one‐step method for preparation of novel 1,3,4‐triaryl‐3,4‐dihydropyrimidin‐2(1H)‐ones has been developed by reaction of aromatic isocyanates with β‐arylamino‐1‐phenylpropan‐1‐ones in refluxing toluene in the presence of KHSO₄ and HCl.     

A general and versatile synthesis of 3‐phenylthio β‐lactams as lead molecules for 3‐methyl‐2‐azetidinones

Ketene‐imine cycloaddition using phosphorus oxychloride and benzenesulfonyl chloride under the described reaction conditions yielded trans 3‐phenylthio 2‐azetidinones in good yields. Desulfurization using Raney nickel and alkylation finally afforded trans 3‐methyl‐2‐azetidinones in a stereoselective manner.     

Synthesis of novel 3,4‐diaryl‐1H‐pyrroles

The synthesis of a series of novel 3,4‐diaryl‐1H‐pyrroles and related arylalkenes from p‐bromo thiophenol, tosylmethyl isocyanide and commercially available materials is reported. Arylalkenes having electron‐withdrawing substituents gave higher yield of 3,4‐diaryl‐1H‐pyrroles.     

Phenacylsulfonylacetic acid methyl ester‐synthon for 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes

A new class of 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes were synthesized by exploiting α‐ketomethylene group in phenacylsulfonylacetic acid methyl ester.     

Synthesis of a novel class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones under solvent‐free and catalyst‐free conditions

A solvent‐ and catalyst‐free one‐pot three‐component condensation reaction approach was developed for the synthesis of a new class of 3‐(2′‐benzothiazolyl)‐2,3‐dihydroquinazolin‐4(1H)‐ones in relatively good yields.