Studies on 4‐Thiazolidinones: Scope of the Reactions of 3‐Aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones with Cyanide and Cyanate Ions

Treatment of 3‐aryl‐2‐thioxo‐1,3‐thiazolidin‐4‐ones 1 with CN^? and NCO^? effected the ring cleavage providing [(cyanocarbonothioyl)amino]benzenes 4 and arylisothiocyanates 5 , respectively. Similar treatment of 5‐(2‐aryl‐2‐oxoethyl) derivatives 2 afforded 2,4‐bis(2‐aryl‐2‐oxoethylidene)cyclobutane‐1,3‐diones 6 along with each of the preceding products. Treatment of the respective (E,Z)‐5‐(2‐aryl‐2‐oxoethylidene) analogues 3b and 3c with CN^? gave 4b and 4c and 2‐(arylcarbonyl)‐2‐methoxy‐4‐oxopentanedinitriles 7b and 7c , in addition to 3,6‐bis[2‐(4‐chlorophenyl)‐1‐methoxy‐2‐oxoethylidene]‐1,4‐dithiane‐2,5‐dione 8c , which has been generated from 3c . Reactions of 3c or 3d with NCO^? provided 5c or 5d , together with 8c or 8d as pure isomers. In the formation of the MeO products 7 and 8 , the solvent (MeOH) has participated. Structures of these products are based on microanalytical and spectroscopic data. Rationalizations for the above transformations are given.     

Synthesis and characterization of some novel bis‐thiazoles

The bis‐thiosemicarbazone derivative 3 was prepared and reacted with N‐aryl‐2‐oxopropane hydrazonoyl chloride 4a‐g and ethyl (N‐arylhydrazono)chloroacetate 7a‐e in absolute ethanol in the presence of triethylamine at reflux afforded a new series of thiazoles 6a‐g and 9a‐e , respectively. Also, thiosemicarbazone derivative 3 was reacted with N′‐phenylbenzohydrazonoyl chloride 10 to give the respective bis‐thiadiazole derivative 12 . Moreover, the reaction of 3 with a number of haloketones and haloesters furnished the respective bis‐thiazole derivatives 14 , 16 , 18 , and 20 . The mechanisms that account for formation of products 6 , 9 , and 12 were discussed. Also, the molecular structure of the synthesized compounds was illustrated by spectroscopic and elemental analysis.     

One‐Pot Synthesis of 2‐Substituted 4‐Aryl‐4,5‐dihydro‐3,1‐benzoxazepines from 2‐(2‐Aminophenyl)‐1‐arylethanols via Dehydration of the Corresponding Amides

An efficient method for the preparation of 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepine derivatives under mild conditions has been developed. The reaction of 2‐(2‐aminophenyl)ethanols 1 with acid chlorides in the presence of excess Et₃N in THF at room temperature gave the corresponding N‐acylated intermediates 2 , which were dehydrated by treatment with POCl₃ to give 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepines 3 in a one‐pot reaction.     

An Efficient Five‐Component Reaction for the Synthesis of 4,4′‐((2‐Oxoindoline‐3,3‐diyl)bis(methylene))bis(2‐aryl‐1H‐pyrrolo[3,4‐c]quinoline‐1,3(2H)‐dione) Derivatives

An efficient cascade process five‐component reaction of isatins and 3‐oxo‐N‐arylbutanamide for the synthesis of 4,4′‐((2‐oxoindoline‐3,3‐diyl)bis(methylene))bis(2‐aryl‐1H‐pyrrolo[3,4‐c]quinoline‐1,3(2H)‐dione) derivatives was reported under mild condition. The advantages of this strategy are easy to obtain raw materials, convenient one‐pot procedure, and simple operation.     

An Unexpected Pyrimidine Ring Transformations in the Reaction of 4‐aryl‐5‐nitro‐6‐bromomethylpyrimidin‐2(1H)‐ones with Anilines

The reaction of 4‐aryl‐6‐bromomethyl‐5‐nitro‐3,4‐dihydropyrimidin‐2(1H)‐ones, containing three possible combinations of substituted and unsubstituted nitrogen atoms with anilines depending on the conditions leads to the products of ring contraction of the pyrimidinone ring into an imidazolone, as well as to the formation of 7‐aryl‐6,7‐dihydroisoxazolo[4,3‐d]pyrimidin‐5(4H)‐one derivatives, and in some cases to the 5‐aminopyrimidinones. The mechanisms of these unusual ring transformations are discussed.     

C5‐Alkyl‐1,3,4‐Oxadiazol‐2‐ones Undergo Dealkylation upon Nitrogen Insertion to Form 2H‐1,2,4‐Triazol‐3‐ones: Synthesis of 1,2,4‐Triazol‐3‐one Hybrids with Triazolothiadiazoles and Triazolothiadiazines

The present study emphasizes on the dealklylation of 3‐aryl‐5‐alkyl‐2‐oxo‐Δ⁴‐1,3,4‐oxadiazoles when reacted with formamide resulting in the formation of 2‐aryl‐2H‐1,2,4‐triazol‐3(4H )‐ones as major product. Subsequent reactions of 2‐aryl‐2H‐1,2,4‐triazol‐3(4H )‐one gave triazolo[3,4‐b ][1,3,4]thiadiazoles and triazolo[3,4‐b ][1,3,4]thiadiazines derivatives incorporated with 1,2,4‐triazol‐3‐one.     

Synthesis of 4‐Arylisocoumarins (=4‐Aryl‐1H‐2‐benzopyran‐1‐ones) through Acidic Hydrolysis of (Z)‐2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes,Followed by Oxidation

4‐Arylisocoumarins (=4‐aryl‐1H‐2‐benzopyran‐1‐ones) 6 were prepared from 2‐(1‐aryl‐2‐methoxyethenyl)‐1‐bromobenzenes 1 . Successive treatment of these bromo styrenes with BuLi and 1‐formylpiperidine gave a mixture of (E)‐ and (Z)‐2‐(1‐aryl‐2‐methoxyethenyl)benzaldehydes 2 . Hydrolysis of (Z)‐isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H‐2‐benzopyran‐1‐ol derivatives 4 (and 5 ), afforded the desired products.     

Synthesis of Some New Heteroylhydrazono‐1,3‐thiazolidin‐4‐ones

A series of (Z)‐methyl‐2‐[(Z)‐3‐substituted‐4‐oxo‐2‐(2‐picolinoyl‐/thiophene‐2‐carbonyl)‐hydrazonothiazolidin‐5‐ylidene]acetates were synthesized by condensation N‐substituted‐(2‐picolinoyl‐, thiophene‐2‐carbonyl)hydrazinecarbothioamides with dimethylacetylenedicarboxylate. The structure of thiazolidin‐4‐one derivatives has been confirmed unambiguously by single crystal X‐ray crystallography.     

An efficient and facile ultrasonic‐accelerated one‐pot synthesis of N‐acetyl‐2‐aryl‐1, 2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones

An application of ultrasonic irradiation in the one‐pot synthesis of N‐acetyl‐2‐aryl‐1,2‐dihydro‐(4H)‐3,1‐benzoxazin‐4‐ones from the condensation reaction between aromatic aldehydes and anthranilic acid in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under mild and solvent‐free conditions at room temperature in the absence of any catalyst to afford the products in good to excellent yields. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:106–113, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20663     

Synthesis of 2‐Aryl‐2,3‐dihydro‐1,8‐naphthyridin‐4(1H)‐ones by Deprotective Cyclization of N‐{3‐[(2E)‐3‐Arylprop‐2‐enoyl]pyridin‐2‐yl}‐2,2‐dimethylpropanamides in Water

A new and convenient method for the preparation of 2‐aryl‐2,3‐dihydro‐1,8‐naphthyridin‐4(1H)‐ones 4 has been developed. Thus, N‐{3‐[(2E)‐3‐arylprop‐2‐enoyl]pyridin‐2‐yl}‐2,2‐dimethylpropanamides 3 are synthesized from commercially available pyridin‐2‐amine using an easily performed three‐step sequence and are subjected to cyclization with deprotection under acidic conditions in H₂O to give the desired products. Similarly, 2‐aryl‐2,3‐dihydro‐1,7‐naphthyridin‐4(1H)‐ones 8 and 2‐aryl‐2,3‐dihydro‐1,6‐naphthyridin‐4(1H)‐ones 12 can be prepared from pyridin‐3‐amine and pyridin‐4‐amine, respectively.     

Synthesis and In Vitro Antibacterial Activities of Novel 2‐Aryl‐3‐(phenylamino)‐2,3‐dihydroquinazolin‐4(1H)‐one Derivatives

An efficient synthesis of novel 2‐aryl‐3‐(phenylamino)‐2,3‐dihydroquinazolin‐4(1H)‐one derivatives using KAl(SO₄)₂.12H₂O (Alum) as a catalyst from an aldehyde and 2‐amino‐N‐phenylbenzohydrazine in ethanol is described. All synthesized derivatives were screened for anti‐bacterial activity. Some compounds exhibited promising anti‐bacterial activity with reference to standard antibiotics.     

Lewis Acids as Mild and Effective Catalysts for the Synthesis of 3,5‐Bis[(hetero)arylidene]piperidin‐4‐ones

The aldol‐crotonic condensation reactions of N‐alkyl‐ and NH‐piperidin‐4‐one derivatives with (hetero)aromatic aldehydes promoted by Lewis acids or bases were examined. This comparative study has revealed three effective catalytic systems based on Lewis acids, i.e., LiClO₄ and MgBr₂ (in the presence of tertiary amine), and BF₃⋅Et₂O, for the synthesis of N‐alkyl‐substituted 3,5‐bis(heteroarylidene)piperidin‐4‐ones, including those bearing acid‐ or base‐labile groups both in the (hetero)aromatic groups and in the alkyl substituent at the N‐atom. The highest reaction rate was observed for LiClO₄‐mediated synthesis. Both MgBr₂‐ and LiClO₄‐mediated syntheses were inefficient in the case of NH‐piperidin‐4‐one, while BF₃⋅Et₂O provided the final compounds in high yields. This catalyst is especially advantageous as it allows simultaneous condensation and deprotection in the case of O‐protected piperidin‐4‐one.     

A Convenient Regioselective Synthesis of Novel 1,4‐Phenylenemethylene‐6,6′‐bis‐([1,2,4‐triazolo]‐[4,3‐b][1,2,4]‐triazin‐7(1H)‐ones)

The target compounds 6,6′‐(1,4‐phenylenedimethylene)‐bis(3‐thioxo‐1,2,4‐triazin‐5(1H )‐one) 4,5 were prepared from reaction of oxazolone 1 with thiosemicarbazide and 4‐phenylthiosemicarbazide, in potassium hydroxide solution, respectively. Reaction of 4 with hydrazonoyl halides 6 afforded triazolotriazine derivatives 7 . Also, 5 reacted with 6 to give the corresponding substitution products 8 . Antimicrobial and antitumor activities for some compounds were studied.     

NaBH4‐I2 mediated chemoselective reduction of γ‐lactam and thio‐γ‐lactam in presence of gem‐dicarboxylates: An easy access to 1,3‐diaryl pyrrolidines

Substituted pyrrolidine derivatives were synthesized in high yield by NaBH₄/I₂ mediated chemoselective reduction of N‐aryl‐γ‐lactam and N‐aryl‐thio‐γ‐lactam‐2,2‐dicarboxylate. With excess NaBH₄/I₂, carbonyl functionality of the ester groups remained unchanged. J. Heterocyclic Chem., (2011).     

Biologically active 1‐arylpiperazines. Synthesis of N‐[3‐(4‐aryl‐1‐piperazinyl)propyl] derivatives of benzoxazinone and benzoxazolinone

The synthesis of new N‐[3‐(4‐aryl‐1‐piperazinyl)propyl] derivatives of 1H‐2,4‐benzoxazin‐3(4H)‐one ( 1a‐b ), 2H‐1,4‐benzoxazin‐3(4H)‐one ( 2a‐b, 3a‐b and 4b ), and benzoxazolin‐2‐one ( 5a‐b ), as biologically active agents, is described.     

Synthetic studies with 3‐Oxo‐N‐[4‐(3‐oxo‐ 3‐phenylpropionylamino)‐phenyl]‐3‐phenylpropionamide

3‐Oxo‐N‐[4‐(3‐oxo‐3‐phenylpropionylamino)‐phenyl]‐3‐phenylpropionamide 1 and its derivative 2‐benzoyl‐N‐[4‐(2‐benzoyl‐3‐(dimethylamino‐acryloylamino)‐phenyl]‐3‐dimethylaminoacrylamide 12 are used for the synthesis of the hitherto not known bis‐heterocyclic amine and bis‐heterocyclic carboxamide derivatives. Plausible mechanisms are discussed for the formation of the new compounds. J. Heterocyclic Chem., (2012).     

3‐Methylthio‐pyrano[4,3‐c]pyrazol‐4(2H)‐ones from 3‐(bis‐methylthio)methylene‐2H‐pyran‐2,4‐diones and hydrazines

A useful synthesis of 3‐methylthio‐6‐methyl‐pyrano[4,3‐c]pyrazol‐4(2H)‐ones via 3‐(bis‐methylthio)methylene‐5,6‐dihydro‐6‐alkyl(aryl)‐2H‐pyran‐2,4‐dione with hydrazine as well as methyl and phenyl hydrazines is described and the mechanism of the formation is discussed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:342–344, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10158     

Electronic spectra and first‐order hyperpolarizability of 4‐(dicyanomethylene)‐2,6‐bis‐ (2′‐thiophene‐vinyl)‐pyran derivatives

On the basis of the ZINDO program, we have designed a program to calculate the first‐order hyperpolarizability β_ijk and β_μ according to the sum‐over‐states (SOS) expression. The first‐order hyperpolarizability of 4‐(dicyanomethylene)‐2,6‐bis‐(2′‐thiophene‐vinyl)‐pyran derivatives were studied. The calculated results were that the 4‐(dicyanomethylene)‐2,6‐bis‐(2′‐thiophene‐vinyl)‐pyran derivatives exhibit good nonlinearity with their β₀ values, which are slightly less than that of the corresponding 2,6‐bis‐styryl‐4‐(dicyanomethylene)‐pyran derivatives. It does not agree with the auxiliary donor–acceptor effects theory. The 4‐(dicyanomethylene)‐2,6‐bis‐(2′‐thiophene‐vinyl)‐pyran derivatives, having two low‐lying electronic excited states that contribute to the molecular hyperpolarizability in an additive manner, are good candidates as chromophores due to their high nonlinearities and good thermal stability. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 65–72, 2001     

Synthesis and Antimicrobial Activity of N‐Aryl‐4‐(cyano/alkoxycarbonyl)‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole Derivatives

A convenient synthesis of a new series of N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carbonitriles and alkyl N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carboxylic acid esters is reported. The newly synthesized 5‐(pyridin‐3‐yl)‐1,2,3‐triazole derivatives are evaluated for their antibacterial and antifungal activity. Some of these triazole derivatives have exhibited moderate antimicrobial activity.     

Synthesis and Anti‐influenza Virus Activity of Novel bis(4H‐chromene‐3‐carbonitrile) Derivatives

An efficient and convenient method for the synthesis of bis(4H‐chromene‐3‐carbonitrile) derivatives by one‐pot, multicomponent reaction of bis‐aldehydes, malononitrile, and dimedone in the presence of a catalytic amount of piperidine is reported. Bis(2‐benzylidene‐1H‐indene)‐1,3‐(2H )‐dione derivatives were obtained as the main products as a result of reaction of the bis(arylidenemalononitriles) with indandione. The anti‐influenza H5N1 virus activities of the newly prepared bis‐chromene derivatives are also investigated.