New N‐(Aryl)‐5‐((quinolin‐8‐yloxy)methyl)‐1,3,4‐oxa/Thiadiazol‐2‐amines and 4‐Aryl‐5‐((quinolin‐8‐yloxy)methyl)‐2H‐1,2,4‐triazole‐3(4H)‐thiones,Synthesis and Characterization

In this study, methyl 2‐(quinolin‐8‐yloxy) acetate ( 2 ) obtained by reaction of 8‐hydroxyquinoline ( 1 ) with methyl chloroacetate was condensed with hydrazine hydrate to afford the carbohydrazide ( 3 ). Thio/semicarbazide derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) were obtained by treatment of the 3 with substituted phenyl iso/thioisocyanates. The 4a , 4b , 4c , 4d , 4e , 4f , 4g on acidic and basic intramolecular cyclization led to N‐(aryl)‐5‐((quinolin‐8‐yloxy)methyl)‐1,3,4‐oxa/thiadiazol‐2‐amines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g ) and 4‐aryl‐5‐((quinolin‐8‐yloxy)methyl)‐2H‐1,2,4‐triazole‐3(4H)‐thiones ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ), respectively. All the synthesized compounds were characterized by spectroscopic techniques and elemental analyses. The thiosemicarbazide ( 4c ) was also confirmed by X‐ray crystallography.     

An efficient synthesis of 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles

Some new target products 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j have been synthesized by reaction of 2‐bromo‐1‐phenylethanone and compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j which were prepared from the combination of thiosemicarbazide and (E)‐3‐aryl‐1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐prop‐2‐en‐1‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j . All the structures were established by MS, IR, CHN, and ¹H NMR spectra data. Synthesis of structure diversity is applied. J. Heterocyclic Chem., (2011).     

Synthesis and Biological Activities of Some New Annulated Pyrazolopyranopyrimidines and Their Derivatives Containing Indole Nucleus

The key intermediate 6‐amino‐3‐methyl‐4‐aryl‐1‐(5′‐substituted‐3′‐phenyl‐1H‐indol‐2′‐carbonyl)‐1,4‐dihydropyrano[2,3‐c]pyrazol‐5‐carbonitriles 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , 3o were prepared by cyclocondensation of 3‐methyl‐1‐(5′‐substituted‐3′‐phenyl‐1H‐indol‐2′‐carbonyl)‐5‐(4H)‐pyrazolones 1a , 1b , 1c with arylidine derivatives of malononitrile 2a , 2b , 2c , 2d , 2e . The compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , 3o were subjected to cyclocondensation reaction with formamide, formic acid, and carbon disulfide to afford the title compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o , and 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j , 6k , 6l , 6m , 6n , 6o , respectively. The structures of all these previously unknown compounds were confirmed by their spectral studies and elemental analysis. These compounds were screened for their antimicrobial and antioxidant activities.     

Synthesis and Antimicrobial Screening of Some Novel Chromones and Pyrazoles with Incorporated Isoxazole Moieties

The title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h and 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h have been synthesized from β‐diketones and chromones, respectively, having 5‐methyl‐3‐phenylisoxazole moiety. Substituted 2‐acetylphenyl 5‐methyl‐3‐phenylisoxazole‐4‐carboxylate 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h were converted into 1‐(2‐hydroxyphenyl)‐3‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)propane‐1,3‐dione 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h by Baker–Venketaraman transformation. Further, the cyclodehydration of diketone 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h with glacial acetic acid in conc. HCl at reflux gave corresponding substituted 2‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐4H‐chromen‐4‐one 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h . The corresponding 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h react with hydrazine hydrate in presence of glacial acetic acid in ethanol at reflux to furnish 2‐(5‐5(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐1H‐pyrazole‐3‐yl)phenol 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h . The structures of all newly synthesized compounds have been confirmed by IR, ¹H NMR, mass spectral data, as well as elemental analysis. The synthesized compounds have been screened for their antimicrobial activity. Some of the compounds show better antimicrobial activity as compared with the reference drugs Streptomycin, Ampicillin, Gentamycin, Cefixime, and Ketoconazole.     

Combined Claisen Rearrangement and Oxidative Cyclization as a Route to Hydroxymethyl Dihydrofuran‐Annulated Coumarins

A convenient and simple method for the synthesis of novel 3,4‐dihydrofuran‐annulated coumarins, 3‐(hydroxymethyl)‐2H‐furo[3,2‐c]chromen‐4(3H)‐ones 5a , 5b , 5c , 5d , 5e , 5f , 5g , by combined Claisen rearrangement and intramolecular regioselective oxidative cyclization of 4‐O‐allyl coumarin intermediates 3a , 3b , 3c , 3d , 3e , 3f , 3g using inexpensive oxidizing agent m‐CPBA is described. The reaction proceeds smoothly by tandem epoxidation/regioselective 5‐exo‐tet‐intramolecular ring opening. The structures of synthesized compounds are established on the basis of spectral data including IR, ¹H NMR, and mass and elemental analyses.     

Synthesis of New (Pyrazol‐3‐yl)‐1,3,4‐oxadiazole Derivatives by Unexpected Aromatization During Oxidative Cyclization of 4,5‐Dihydro‐1H‐pyrazole‐3‐carbohydrazones and Their Biological Activities

A series of novel 2‐(4‐(4‐chlorophenyl)‐1H‐pyrazol‐3‐yl)‐5‐(Aryl)‐1,3,4‐oxadiazoles were synthesized by unexpected aromatization during oxidative cyclization of 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazones using chloramine‐T as an oxidant. The hydrazones were derived from 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazide and various substituted aldehydes. The structure of the synthesized compounds was confirmed by FTIR, ¹H NMR, ¹³C NMR, and mass spectral data. The synthesized compounds were evaluated for their antitubercular and antioxidant activities. All the compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h and 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h showed good antitubercular activity against Mycobacterium tuberculosis (minimum inhibitory concentration = 25 µg/mL for 4f and 4g , 50–100 µg/mL for the rest). However, all the compounds exhibited poor antioxidant activity against 1,1‐diphenyl‐2‐picryl‐hydrazil free radical.     

A Mild and Efficient Synthesis of Novel Isoxazolyl‐Benzo[d]Pyrazino[2,1‐b] [1,3]Oxazoles

Synthesis of novel 2‐3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl‐4,10a‐diaryl‐1,10a‐dihydro‐2H‐benzo[d]pyrazino[2,1‐b][1,3]oxazoles 5 were simply achieved by the reaction of 2‐[3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl(2‐oxo‐2‐arylethyl)amino]‐1‐aryl‐1‐ethanones 3 with o‐aminophenol 4 in the presence of CAN catalyst. The intermediates, 2‐[3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl(2‐oxo‐2‐arylethyl)amino]‐1‐aryl‐1‐ethanones 3 , were prepared by the reaction of 4‐amino‐3‐methyl‐5‐styrylisoxazole 1 , with phenacylbromides 2 in ethanol in the presence of K₂CO₃. The structures of the newly synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l and 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l have been confirmed by analytical and spectral data.     

A New Route to Vitamin E Key‐Intermediates by Olefin Cross‐Metathesis

Ru‐Catalyzed olefin cross‐metathesis (CM) has been successfully applied to the synthesis of several phytyl derivatives ( 2b, 2d – f, 3b ) with a trisubstituted C?C bond, as useful intermediates for an alternative route to α‐tocopheryl acetate (vitamin E acetate; 1b ) (Scheme 1). Using the second‐generation Grubbs catalyst RuCl₂(C₂₁H₂₆N₂)(CHPh)PCy₃ (Cy = cyclohexyl; 4a ) and Hoveyda–Grubbs catalyst RuCl₂(C₂₁H₂₆N₂){CH‐C₆H₄(O‐ⁱPr)‐2} ( 4b ), the reactions were performed with various C‐allyl ( 5a – f, 7a,b ) and O‐allyl ( 8a – d ) derivatives of trimethylhydroquinone‐1‐acetate as substrates. 2,6,10,14‐Tetramethylpentadec‐1‐ene ( 6a ) and derivatives 6c – e of phytol ( 6b ) as well as phytal ( 6f ) were employed as olefin partners for the CM reactions (Schemes 2 and 5). The vitamin E precursors could be prepared in up to 83% isolated yield as (E/Z)‐mixtures.     

Synthesis of fluorine containing N‐benzyl‐1,2,3‐triazoles and N‐methyl‐pyrazoles from conjugated alkynes

1, 3‐Dipolar‐cycloaddition reaction of fluoro substituted 3‐aryl‐propynenitriles 1 with benzyl azide 2 afforded the expected 3‐benzyl‐5‐aryl‐3H‐[1,2,3]triazole‐4‐carbonitrile 3 and 1‐benzyl‐5‐aryl‐1H‐[1,2,3]‐triazole‐4‐carbonitrile 4 in good yield. However, 1,3‐dipolar cycloaddition of diazomethane 5 with 3‐aryl‐propynenitriles 1 resulted in the exclusive formation of N‐methyl‐pyrazole derivatives 6 and 7 .     

Synthesis of New Derivatives of 4‐(4,7,7‐Trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine

Cyclocondensation of 5‐amino‐6‐methyl‐2‐morpholinopyrimidine‐4‐thiol ( 1 ) and 2‐bromo‐5,5‐dimethylcyclohexane‐1,3‐dione ( 2 ) under mild reaction condition afforded 4,7,7‐trimethyl‐2‐morpholino‐7,8‐dihydro‐5H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐9(6H )‐one ( 3 ). The ¹H and ¹³C NMR data of compound ( 3 ) are demonstrated that this compound exists primarily in the enamino ketone form. Reaction of compound ( 3 ) with phosphorous oxychloride gave 4‐(9‐chloro‐4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐2‐yl)morpholine ( 4 ). Nucleophilic substitution of chlorine atom of compound ( 4 ) with typical secondary amines in DMF and K₂CO₃ furnished the new substituted derivatives of 4‐(4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐2‐yl)morpholine ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h ). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.     

An Innovative Protocol for the Synthesis of 3‐(Pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles and 9,10‐Dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles

Herein, we present an innovative, novel, and highly convenient protocol for the synthesis of 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ), which have been delineated from the reaction of 4‐sec‐amino‐2‐oxo‐6‐aryl‐2H‐pyran‐3‐carbonitrile ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) and 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐benzo[h]chromene‐3‐carbonitriles ( 9a , 9b , 9c , 9d , 9e ) with 2‐acetylpyridine ( 5 ) through the ring transformation reaction by using KOH/DMF system at RT. The salient feature of this procedure is to provide a transition metal‐free route for the synthesis of asymmetrical 1,3‐teraryls like 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ). The novelty of the reaction lies in the creation of an aromatic ring from 2H‐pyran‐2‐ones and 2H‐benzo[h]chromene‐3‐carbonitriles via two‐carbon insertion from 2‐acetylpyridine ( 5 ) used as a source of carbanion.     

Synthesis of Novel 3‐(3‐(5‐Methylisoxazol‐3‐yl)‐7H‐[1,2,4]Triazolo [3,4‐b][1,3,4]Thiadiazin‐6‐yl)‐2H‐Chromen‐2‐Ones

A novel series of coumarin substituted triazolo‐thiadiazine derivatives were designed and synthesized by using 5‐methyl isoxazole‐3‐carboxylic acid ( 1 ), thiocarbohydrazide ( 2 ), and various substituted 3‐(2‐bromo acetyl) coumarins ( 4a , 4b , 4c , 4e , 4d , 4f , 4g , 4h , 4i , 4j ). Fusion of 5‐methyl isoxazole‐3‐carboxylic acid with thiocarbohydrazide resulted in the formation of the intermediate 4‐amino‐5‐(5‐methylisoxazol‐3‐yl)‐4H‐1,2,4‐triazole‐3‐thiol ( 3 ). This intermediate on further reaction with substituted 3‐(2‐bromo acetyl) coumarins under simple reaction conditions formed the title products 3‐(3‐(5‐methylisoxazol‐3‐yl)‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl‐2H‐chromen‐2‐ones ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j ) in good to excellent yields. All the synthesized compounds were well characterized by physical, analytical, and spectroscopic techniques.     

Synthesis and antimicrobial and pharmacological properties of new thiosemicarbazide and 1,2,4‐triazole derivatives

Reaction of 4‐phenyl‐4H‐1,2,4‐triazole‐3‐thione with ethyl bromoacetate has led to the formation of ethyl [(4‐phenyl‐4H‐1,2,4‐triazol‐3‐yl)sulfanyl]acetate 1 , the structure of which was confirmed by X‐ray analysis. In the next reaction with 80% hydrazide hydrate, appropriate hydrazide 2 was obtained, which in reaction with isothiocyanates was converted to new acyl derivatives of thiosemicarbazides 2 , 3 , 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h . The cyclization of these compounds in alkaline media has led to formation of new derivatives of 5‐{[(4‐phenyl‐4H‐1,2,4‐triazole‐3‐yl)sulfanyl]methyl}‐4H‐1,2,4‐triazole‐3(2H)‐thiones 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4j . The structure of the compounds was confirmed by elementary analysis and IR, ¹H‐NMR, ¹³C‐NMR, and MS spectra. Compounds 2 , 3 , 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h and 4a , 4b , 4c , 4d , 4e , 4f , 4g were screened for their antimicrobial activities, and the influence of the compounds 4a , 4b , and 4e , 4f , 4g on the central nervous system of mice in behavioral tests was examined. J. Heterocyclic Chem., (2011).     

Synthesis of Oxazolo[5,4‐d][1,2,4]triazolo[4,3‐a]pyrimidines as a New Class of Heterocyclic Compounds

Several new derivatives of oxazolo[5,4‐d]pyrimidine ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h ) have been synthesized through the reaction of 2,4‐dichloro‐6‐methyl‐5‐nitropyrimidine ( 2 ) with aryl carboxylic acids in refluxing POCl₃. Further treatment of compounds ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h ) with hydrazine hydrate gave the hydrazine derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h ) that were subsequently cyclized into a novel heterocyclic system, oxazolo[5,4‐d][1,2,4]triazolo[4,3‐a]pyrimidine ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o , 5p ) and ( 7a , 7b , 7c , 7d ) on treatment with triethylorthoesters or carbondisulfide and alkylhalides, respectively.     

Synthesis of 2‐Arylquinazolin‐4(3H)‐ones by N‐Aryl Benzamidines with Aromatic Carbonates

The reaction of N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n with diphenyl carbonate 2a or ethyl phenyl carbonate 2b synthesized 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n in simple and safe process with good yields (71–90%). It was suggested that different electron‐donating substituent in N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n afforded similar effect to the yields of 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n . In these reactions, N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n built up intermediate compounds by nucleophilic addition to carbonates 2 to give annulation products 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , following to cyclization involving the elimination of ethanol/phenol.     

Synthesis and structural characterisation of 4H‐1,3‐benzothiazine derivatives

The ring‐closure reactions of N‐arylthiomethylaroylamide derivatives ( 1a‐g ) in the presence of phospho ‐rus oxychloride gave 2‐aryl‐4H‐1,3‐benzo‐thiazines (2a‐g). 2‐(3‐Chlorophenyl)‐6‐methyl‐4H‐1,3‐benzoth‐iazine ( 2b ) was reduced with Zn to obtain the corresponding 2,3‐dihydro derivative ( 3b ). Potassium permanganate oxidation of 2‐(4‐chlorophenyl)‐2,3‐diethoxy‐4H‐ ( 2e ) and 2‐(2‐fluorophenyl)‐6,7‐diefhoxy‐4H‐1,3‐benzo‐thiazines ( 2g ) gave the corresponding 4‐ones ( 4e,g ). The reactions of 2‐(4‐chlorophenyl)‐6‐mefhyl‐4H‐1,3‐benzofhiazine ( 2c ) with substituted acetyl chlorides led to linearly condensed ß‐lactams ( 5a,b ). The structures of the compounds studied were confirmed by ¹H and ¹³C NMR and by their characteristic mass spectrometric fragmentations.     

4‐Toluenesulfonamide as a Building Block for Synthesis of Novel Triazepines,Pyrimidines, and Azoles

N‐{(E)‐(dimethylamino)methylidenearbamothioyl}‐4‐toluenesulfonamide ( 2 ) was obtained by reaction of N‐carbamothioyl‐4‐toluenesulfonamide ( 1 ) with dimethylformamide dimethylacetal or alternatively by the reaction of 1‐(dimethylamino)methylidenethiourea with tosyl chloride. Compound 2 was reacted with substituted anilines to yield anilinomethylidine derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g . Treatment of 3a , 3b , 3c , 3d , 3e , 3f , 3g with phenacyl bromide gave triazepines 4a , 4b , 4c , 4d , 4e , 4f , 4g and imidazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g . Esterification of compound 3e afforded ester derivative 6 , which was subjected to react with hydrazine to yield hydrazide derivative 7 . Oxadiazole 8 was obtained by reaction of 7 with CS₂/KOH. Compound 3e was treated with o‐aminophenol or o‐aminothiophenol to give benzazoles 9a , 9b . N‐(Diaminomethylidene)‐4‐toluenesulfonamide ( 10 ) reacted with enaminones to yield pyrimidines 11 , 12 , 13 , respectively. The structures of the compounds were elucidated by elemental and spectral analyses. Some selected compounds were screened for their in vitro antifungal activity. In general, the newly synthesized compounds showed good antifungal activity.     

The Synthesis,Spectral, and Electrochemical Characterization of Novel Alkoxybenzoquinone Derivatives

The novel monosubstituted benzoquinone compounds 3e , 3g , 3h ; 2,5‐O‐ substituted benzoquinone compounds 4a , 4b , 4c , 4d , 4e 4g and known compound 4h and 2,6‐O‐ substituted benzoquinone compounds 5e , 5f , 5g , 5h were obtained by the reaction of p‐chloranil ( 1 ) and related alcohol compounds in potassium carbonate (K₂CO₃) solution of acetonitrile or chloroform with Et₃N. The novel cyclic compounds 7 , 8 and 10 , 11 were obtained from the reaction of p‐chloranil ( 1 ) and diols in potassium carbonate (K₂CO₃) solution of acetonitrile at room temperature. The structures of novel compounds were characterized by using micro analysis, FT‐IR, ¹H‐NMR, ¹³C‐NMR, MS and cyclic voltammetry.     

Probing the Rotational Dynamics of meso‐(2‐Substituted)aryl Substituents in A2B‐Type Subporphyrins

A₂B‐type B‐methoxy subporphyrins 3 a – g and B‐phenyl subporphyrins 7 a – c , e , g bearing meso‐(2‐substituted)aryl substituents are synthesized, and their rotational dynamics are examined through variable‐temperature (VT) ¹H NMR spectroscopy. In these subporphyrins, the rotation of meso‐aryl substituents is hindered by a rationally installed 2‐substituent. The rotational barriers determined are considerably smaller than those reported previously for porphyrins. Comparison of the rotation activation parameters reveals a variable contribution of ΔH^≠ and ΔS^≠ in ΔG^≠. 2‐Methyl and 2‐ethyl groups of the meso‐aryl substituents in subporphyrins 3 e , 3 f , and 7 e induce larger rotational barriers than 2‐alkoxyl substituents. The rotational barriers of 3 g and 7 g are reduced by the presence of the 4‐dibenzylamino group owing to its ability to stabilize the coplanar rotation transition state electronically. The smaller rotational barriers found for B‐phenyl subporphyrins than for B‐methoxy subporphyrins indicate a negligible contribution of S_N1‐type heterolysis in the rotation of meso‐aryl substituents.     

Synthesis and Structure Elucidation of New Regioisomeric 2‐Alkylamino‐6‐aryl‐8,9‐dihydropyrimido[4,5‐b][1,4]diazepin‐4(7H)‐ones

Novel 2‐Alkylamino‐6‐aryl‐8,9‐dihydropyrimido[4,5‐b][1,4]diazepin‐4(7H)‐ones 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o were prepared regioselectively by the reaction of 2‐alkylamino‐5,6‐diaminopyrimidin‐4(3H)‐ones 3a , 3b , 3c and dimethylamino propiophenones (Mannich bases) 4a , 4b , 4c , 4d , 4e , 4f . The combination of conventional heating and microwave irradiation approaches provided the possibility of working with both stable and sensitive diaminopyrimidines by controlling parameters such as reaction rates, temperature, and power of irradiation. All products were fully characterized by detailed NMR measurements.