bluuebunny/crossref_metadata_2025_split huggingface dataset:
New efficient approach for the synthesis of 2‐alkyl(aryl) substituted 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones
Authors: Bonacorso Helio G. , Righi Fernando J. , Rodrigues Isadora R. , Cechinel Cleber A. , Costa Michelle B. , Wastowski Arci D. , Martins Marcos A. P. , Zanatta Nilo 
Published: March 2009

Abstractmagnified imageA new, efficient and easy route for the preparation of a series of 2‐alkyl(aryl) substituted 4‐oxo‐4H‐pyrido‐[1,2‐a]pyrimidines, where alkyl = CH3; aryl = C6H5, 4‐FC6H4, 4‐ClC6H4, 4‐BrC6H4, 4‐CH3C6H4, 4‐OCH3C6H4, 4‐NO2C6H4in 45–80 % yield from the reaction of β‐alkoxyvinyl trichloromethyl ketones with 2‐aminopyridine under mild conditions, is then reported.
Convenient synthesis of N‐substituted 1‐alkyl and 1‐aryl‐3‐aminoisoquinolines
Authors: Cánepa Alicia S. , Bravo Rodolfo D. 
Published: March 2009

Abstractmagnified imageCyclocondensation of 2‐acylphenylacetonitriles 1 with amines affords 1‐substituted 3‐aminoisoquinolines 2 in good yields.
Δ2‐Isoxazolines from β,γ‐unsaturated oximes
Authors: Mosher Michael D. , Emmerich Laura G. , Frost Katherine S. , Anderson Benjamin 
Published: March 2009

Abstractmagnified image3,5‐Disubstituted Δ2‐isoxazolines can be prepared using the palladium‐mediated nucleometalation / methoxycarbonylation of β,γ‐unsaturated oximes. This novel route to this class of compounds is tolerant of a wide variety of functionality in the starting material, and provides a rapid route to highly functionalized isoxazolines.
Studies with condensed aminothiophenes: Further investigation on the reactivity of condensed aminothiophenes toward electron poor and acetylenes under microwave heating
Authors: Al‐Saleh Balkis , El‐Apasery Morsy A. 
Published: March 2009

Abstractmagnified imageThe reaction of aminothienopyridazines 8a,b, aminothienocoumarin 13 and aminothienonaphthopyran 14 with enaminones 9, 17 and 20a,b under microwave irradiation affords either a mixture of both condensations C‐1 alkylation products 15 and 16 or amino moiety alkylation and diethylamine elimination or only one of these products depending on nature of substituents on the thiophene ring. On the other hand reaction of these condensed aminothiophenes with 3‐dimethylaminoacrylaldehyde afforded 24 and 25.
Some nucleophilic substitutions in 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine
Authors: Arias Lucina , Salgado‐Zamora Héactor , Campos Elena , Reyes Alicia , Cervantes Humberto , Taylor Edward C. 
Published: March 2009

Abstractmagnified imageIn some nucleophilic substitution reactions of 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine, nitrogen (alkylamines, guanidine) and oxygen nucleophiles (alkoxides) underwent substitution of the 2‐cyano group, while sulfur nucleophiles (alkylthiols) underwent substitution of the 3‐nitro group.
Synthesis of 8‐substituted tetrahydro‐γ‐carbolines
Authors: Bridoux Alexandre , Goossens Laurence , Houssin Raymond , Héanichart Jean‐Pierre 
Published: March 2009

Abstractmagnified imageThe Fischer reaction is applied to the synthesis of 8‐substituted tetrahydro‐γ‐carbolines with electron‐donating or electron‐withdrawing groups, using catalytic or thermal methods. The reaction conditions must be varied according to the nature of the N 1 substituent of the piperidone. The best results are observed when a releasing group is present on the arylhydrazine and a benzyl substituent on the nitrogen of piperidone. Formation of carbolines with a withdrawing substituent is observed in soft acidic conditions; in others, reaction ended at the hydrazone level or did not evolve.
A new approach to the total synthesis of (±)‐20‐ epidasycarpidone
Authors: Uludag Nesimi , Patir Suleyman , Höukelek Tuncer 
Published: March 2009

Abstractmagnified imageIn this study, a new synthetic route to the total synthesis of (±)‐20‐ epidasycarpidone (1b) is described. This route involves acid catalyzed ring closure and the formation of the intermediate 13 in the key step. The relative stereochemistry of 13 has been confirmed by X‐ray structure analysis. The tetracyclic intermediate 13 was synthesized through several steps starting from 3. The removal of the protecting group of 13 yielded the lactam 15, which was reduced by Red‐Al® to give 16. The synthesis of (±)‐20‐ epidasycarpidone (1b) was finally completed by the oxidation of 16.
Thermolysis of N,N″‐1,ω‐alkanediyl‐bis[n′‐organylthiourea] derivatives
Authors: Hassan Alaa A. , Döupp Dietrich 
Published: March 2009

Abstractmagnified imageThe course of microwave assisted or conventional thermal intramolecular heterocyclization of the title compounds has been found to be dependent on the length of the alkanediyl chain. While 1,3‐propanediyl‐bisthioureas 5a‐c gave both 2‐thioxoperhydropyrimidine‐1‐carbothioamides 8a‐c and 8‐amino‐3,4,5,6‐tetrahydro‐1,3,7‐thiadiazocine‐2‐thiones 10a‐c, thermolysis of 1,4‐butanediyl‐bisthioureas 6a‐c and 1,6‐hexanediyl‐bisthioureas 7a‐c under the same conditions gave solely 9‐amino‐4,5,6,7‐tetrahydro‐1,3,8‐thiadiazonine‐2‐thiones 11a‐c and 11‐amino‐1‐thia‐3,10‐diazacycloundec‐10‐ene‐2‐thiones 12a‐c, respectively. Symmetric N,N′‐diorganylthioureas 4a‐c were formed in all cases as minor byproducts.
A new method for the synthesis of substituted indeno[1,2‐b]thiophene with subsequent ring expansion to form substituted thieno[3,2‐c]quinoline
Authors: Castle Lyle W. , Elmaaty Tarek Abou 
Published: March 2009

Abstractmagnified image2‐Phenacylindan‐1,3‐dione (3) was treated with Lawesson's reagent (2,4‐bis(4‐methoxyphenyl)‐1,3‐dithia‐2,4‐diphosphetane‐2,4‐disulfide) to form 2‐phenyl‐4H‐indeno[1,2‐b]thiophene‐4‐one (4). Compound 4 was subsequently reacted with hydroxyl amine to form the oxime (5), which, upon treatment with polyphosphoric acid, underwent ring expansion (Beckmann rearrangement) to give 2‐phenylthieno[3,2‐c]quinoline‐4(5H)one.
Stereochemistry, tautomerism, and reactions of acridinyl thiosemicarbazides in the synthesis of 1,3‐thiazolidines
Authors: Balentová Eva , Imrich Ján , Bernáat Juraj , Suchá Lucia , Vilková Mária , Kristian Pavol , Pihlaja Kalevi , Klika Karel D. , Pröanayová Nad'a 
Published: March 2009

Abstractmagnified imageAcridin‐9‐yl hydrazine upon treatment with various isothiocyanates (RNCS, R = methyl, allyl, phenyl, p‐methoxy phenyl, and p‐nitro phenyl) yielded the corresponding thiosemicarbazides with acridine substituted on the carbazide‐type side. The alkyl‐substituted compounds were present in solution as equilibria consisting of the major H‐10, H‐12 tautomer (either E or Z or both about the C13‐N14 bond) and the minor H‐10, SH tautomer (either E or Z or both). The major species for the aromatic‐substituted compounds was the H‐10, H‐12 E tautomer, with the evident minor species being the H‐10, H‐12 Z tautomer. The thiosemicarbazides were each quantitatively converted into the analogous semicarbazides upon treatment with mesitylnitrile oxide wherein all structures were present in solution as the H‐10 tautomers with Z conformation about the C13‐N14 bond. Methylation of the compounds with methyl iodide yielded S‐methylated compounds wherein the Z configuration dominated in each case over the E configuration along the N12‐C13 double bond. Treatment of the thiosemicarbazides with methyl bromoacetate resulted in the formation of 1′,3′‐thiazolidin‐4′‐ones wherein the Z configuration predominated in each case over the E configuration along the N12C13 double bond. With bromoacetonitrile as the bifunctional electrophile, the initial 1′,3′‐thiazolidin‐4′‐imines that formed spontaneously underwent Dimroth‐type rearrangement to the regiosiomeric 1′,3′‐thiazolidin‐4′‐imines.
Convenient synthesis of novel 5‐substituted 3‐methylisoxazole‐4‐sulfonamides
Authors: Filimonov Sergey I. , Korsakov Mikhail K. , Dorogov Mikhail V. , Kravchenko Dmitry V. , Tkachenko Sergey E. , Ivachtchenko Alexandre V. 
Published: March 2009

Abstractmagnified imageA number of novel sulfonamide derivatives of 5‐substituted‐3‐methylisoxazole were synthesized and characterized, starting from 3,5‐dimethylisoxazole. Key steps include the generation of 3,5‐dimethylisoxazole‐4‐sulfonamides followed by their reactions with N‐(dimethoxymethyl)‐N,N‐dimethylamine or various aromatic and heteroaromatic aldehydes. As a result, a series of novel aryl/heteroaryl‐ and aminovinylsubstituted derivatives of the isoxazole heterocycle were obtained. The scope and limitations of the developed approach are discussed.
Synthesis of fluorine containing N‐benzyl‐1,2,3‐triazoles and N‐methyl‐pyrazoles from conjugated alkynes
Authors: Rama Rao V.V.V.N.S. , Lingaiah B.P.V. , Yadla R. , Rao P. Shanthan , Ravikumar K. , Swamy G.Y.S.K. , Narsimulu K. 
Published: March 2009

Abstractmagnified image1, 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 2‐amino‐4‐aryl‐7,7‐dimethyl‐5‐oxo‐4H‐5,6,7,8‐tetrahydrobenzo[b]pyran derivatives in ionic liquid medium
Authors: Li Yuling , Du Baixiang , Wang Xiangshan , Shi Daqing , Tu Shujiang 
Published: March 2009

Abstractmagnified imageIn this paper, preparation of 2‐Amino‐4‐aryl‐7,7‐dimethyl‐5‐oxo‐4H‐5,6,7,8‐tetrahydrobenzo[b]pyran derivatives from aromatic aldehyde, malononitrile or cyanoacetate and 5,5‐dimethyl‐1,3‐cyclohexanedione in ionic liquid [bmim+][BF4−] was described. Compared with other methods, this new method has the advantages of easier work‐up, milder reaction conditions, high yields and environmentally benign procedure.
One pot synthesis of substituted dihydroindeno[1,2‐b]indoles and dihydrobenzo[a]carbazoles by photostimulated reactions of o‐iodoaniline with carbanions by the SRN1 mechanism
Authors: Barolo Silvia M. , Rossi Roberto A. , Rosales Ceciréa , Angel Guío Jorge E. 
Published: March 2009

Abstractmagnified imageThe photostimulated reaction of enolate anions of cyclic aromatic ketones such as substituted indan‐1‐ones and 3,4‐dihydro‐2H‐naphthalen‐1‐one with o‐iodoaniline in DMSO affords 1‐, 2‐, 3‐, and 4‐methoxy‐5,10‐dihydroindeno[1,2‐b]indoles (34‐40%), 1,2‐, 1,4‐, and 2,3‐dimethoxy‐5,10‐dihydroindeno[1,2‐b]‐indoles (31‐43%), and 1‐, 2‐, and 3‐methoxy‐5,11‐dihydro‐6H‐benzo[a]carbazoles (42‐61%) by the SRN1 mechanism in one pot reactions.
The synthesis of symmetrical (2‐indolyl)ethynes and reduced congeners via palladium‐catalyzed couplings of 2‐bromoindole precursors
Authors: Sercel Anthony D. , Hollis Showalter H. D. 
Published: March 2009

Abstractmagnified imageStarting from a series of 2‐bromo‐1‐methylindole precursors (1b‐e) activated in the 3‐position with aldehyde, ester, or amide functionality, two approaches have been developed toward the synthesis of 2,2′‐bis(indolyl)ethynes and reduced congeners via palladium(0)‐ or palladium(II)‐catalyzed couplings. The first approach utilized Sonogashira coupling of (trimethylsilyl)acetylene to introduce the two‐carbon linker followed by desilylation and further coupling with starting 2‐bromoindole. A second shorter and more efficient route engaged the starting 2‐bromoindole in a double Stille coupling with bis(tributylstannyl) acetylene or (E)‐1,2‐bis(tributylstannyl)ethylene to provide desired homodimers in one step. Subsequent transformations of dimeric intermediates led to target acids 7a‐c and derived amides 8a‐c and 9. When tested against a panel of tyrosine kinases, each target compound was found to be inactive.
Synthesis of 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydropyridine‐5‐carboxylic acid diethylamides as potential anti‐inflammatory agents
Authors: Gangapuram Madhavi , Redda Kinfe K. 
Published: March 2009

Abstractmagnified imageFifteen novel 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydro‐ pyridine‐5‐carboxylic acid diethylamide (7, 15) were synthesized in fair to good yields via sodium borohydride reduction of the corresponding 1‐(substituted phenylcarbonyl/ sulfonylimino)‐3‐diethylcarbamoyl pyridinium ylides (6, 14) in absolute ethanol.
Structure determination of N‐methyl‐tetrahydro‐5H‐indazol‐5‐ones
Authors: Josef Kurt A. , Dandu Reddeppareddy , Tao Ming , Hudkins Robert L. 
Published: March 2009

Abstractmagnified imageThis paper communicates the (regio) synthesis and a convenient NMR structural assignment method for N‐methyl‐tetrahydro‐5H‐indazol‐5‐one isomers. The cyclization reaction of 7‐(hydroxymethylene)‐1,4‐dioxaspiro[4,5]decan‐8‐one (3) with methylhydrazine yields, after de‐protection predominately the N‐2 methyl isomer 2. Analysis of the product ratio and structural assignments are based on NMR data including NOE difference experiments and subsequently confirmed with X‐ray crystallography. These findings are in sharp contrast with the literature. The experimental conditions used to optimize the synthesis of the individual isomers are discussed.
Unusual structures derived from N‐acridin‐9‐yl methyl N′‐acridin‐9‐yl thiourea based on the propensity of N‐10 to retain H
Authors: Klika Karel D. , Pihlaja Kalevi , Imrich Ján , Vilková Mária , Bernát Juraj 
Published: March 2009

Abstractmagnified imageN‐Acridin‐9‐yl methyl N′‐acridin‐9‐yl thiourea spontaneously spiro cyclises via nucleophilic attack of the methylene carbon onto the C‐9 of the other acridine moiety. The thiourea, upon reaction with bromoacetonitrile, provided a spiro fused‐bicyclic product displaying unusual dynamic behavior.
Microwave‐assisted claisen rearrangement. Application to the synthesis of angelicin derivatives
Authors: Valizadeh Hassan , Shockravi Abbas 
Published: March 2009

Abstractmagnified image4′‐(Hydroxy, chloro, amino, acetoxy and methoxy)‐methyl‐4,5′‐dimethylangelicins were efficiently and rapidly synthesized via Claisen rearrangement of 4‐methyl‐7‐[4‐(hydroxy, chloro, amino, acetoxy and methoxy)‐but‐2‐ynyloxy]‐coumarins respectively under microwave irradiation. Prominent among the advantages of this new method are operational simplicity, good yields in short reaction times and easy work‐up procedures employed.
Pictet‐spengler cyclization in room temperature ionic liquid: A convenient access to tetrahydro β‐carbolines
Authors: Muthukrishnan M. , More Shivaji V. , Garud Dinesh R. , Ramana C. V. , Joshi R. R. , Joshi R. A. 
Published: March 2009

Abstractmagnified image1,2,3,4‐Tetrahydro‐β‐carbolines have been synthesized in moderate to good yields in short reaction time using the ionic liquid [bbim] BF4 as reaction medium and promoter. There was no need for the use of an additional catalyst normally employed in Pictet‐Spengler condensation.
The convenient synthesis of benzimidazole derivatives catalyzed by I2 in aqueous media
Authors: Sun Peipei , Hu Zhixin 
Published: March 2009

Abstractmagnified imageIn the presence of catalytic amount of iodine, in THF‐H2O, the condensation of aldehydes with 1,2‐phenylenediamine gave the benzimidazole derivatives under mild conditions in good yields. The method can be used for the synthesis of 2‐substituted benzimidazoles or 1,2‐disubstituted benzimidazoles.
Synthesis of a library of 1,2,3,7‐tetrasubstituted indolizines using poly(ethylene glycol) as soluble support
Authors: Yue Guizhou , Chen Zuxing , Yang Guichun 
Published: March 2009

Abstractmagnified imageA library of 1,2,3,7‐tetrasubstituted indolizines has been synthesized using poly(ethylene glycol) (PEG) as soluble polymer support. The PEG‐bound pyridinium salts reacted with alkenes or alkynes in the presence of Et3N via 1,3‐dipolar cycloaddition to give PEG‐bound indolizine derivatives, which were cleaved by 1 % KCN/MeOH to afford 1,2,3,7‐tetrasubstituted indolizines in good to excellent yields.
Study of synthesis of 2‐(2‐alkoxyphenyl)‐1H‐imidazoles. Comparison of oxidative aromatization reactions of imidazolines
Authors: Pařík Patrik , Šenauerová Sylva , Lišková Vlasta , Handlíř Karel , Ludwig Miroslav 
Published: March 2009

Abstractmagnified imageThe reaction of methyl salicylate with ethane‐1,2‐diamine has been used to prepare 2‐(2‐hydroxyphenyl)‐1H‐imidazoline. This compound was alkylated with alkyl halides to give five new 2‐(2‐alkoxyphenyl)‐1H‐imidazolines (alkyl = propyl, isopropyl, isobutyl, sec‐butyl, benzyl). Seven types of transformation reactions of imidazolines into the respective imidazoles were tested. Out of them successful were the dehydrogenation on palladium in toluene (several‐day refluxing), oxidation with activated manganese dioxide in toluene (several‐hour heating at 60 °C), and the oxidation with potassium nitrosodisulfonate (Fremy's salt) at room temperature. Seven new 2‐(2‐alkoxyphenyl)‐1H‐imidazoles were synthesized (alkyl = ethyl, propyl, isopropyl, butyl, isobutyl, sec‐butyl, benzyl) via mentioned methods. Comparison of individual oxidative aromatization reactions is discussed from the point of view of experimental arrangement, reaction time and conditions, purity of the products obtained, and yields.
Transformation of 4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehydes into pyrazolo[3,4‐B]pyridines
Authors: Stankovičová Henrieta , Gáplovský Anton , Lácová Margita , Chovancová Jarmila , Puchala Agnieszka 
Published: March 2009

Abstractmagnified imageReaction of 6‐methyl‐4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehyde 1 with 5‐amino‐3‐methyl‐1‐phenylpyrazole 2 in alcoholic reaction media in the presence of 4‐toluenesulfonic acid as catalyst afforded 5‐(2‐hydroxy‐5‐methylbenzoyl)‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine 3 and 2‐methoxy‐6‐methyl‐3‐(3‐methyl‐1‐phenylpyrazol‐5‐ylaminomethylene)chroman‐4‐one 7. We explain the mechanism of formation of both products on the basis of kinetic study of individual reaction steps.
An efficient one‐pot synthesis of 5‐aryl substituted 2‐amino‐5,8‐dihydropyrido[2,3‐D] pyrimidin‐4,7‐diones under microwave irradiationl without catalyst
Authors: Tu Shujiang , Wang Qian , Xu Jianing , Zhu Xiaotong , Zhang Jinpeng , Jiang Bo , Jia Runhong , Zhang Yan , Zhang Junyong 
Published: March 2009

Abstractmagnified imageA series of 5‐aryl substituted 2‐amino‐5,8‐dihydropyrido[2,3‐d]pyrimidin‐4,7‐diones were synthesized through one‐pot condensation of 2,6‐diaminopyrimidin‐4‐one, aldehyde and Meldrum's acid using glycol as energy transfer agent under microwave irradiation without catalyst. The one‐pot protocol in the absence of catalyst has the advantage of good yield (86‐95%), short route and reaction time (3‐6 min) and environmentally friendly.
Synthesis of 1‐acyl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones VIA lewis acid‐mediated rearrangement of 3‐acyloxypyrazoles
Authors: Maruoka Hiroshi , Yamagata Kenji , Okabe Fumi , Tomioka Yukihiko 
Published: March 2009

Abstractmagnified imageThe unusual formation of 1‐acyl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones starting from 3‐acyloxypyrazoles by Fries‐type rearrangement is described. Under normal conditions, acylation of 2,4‐dihydro‐3H‐pyrazol‐3‐ones 1 and 2 with acid chlorides or anhydrides in the presence of triethylamine gave the corresponding 3‐acyloxypyrazoles 3a‐f and 4a‐f. Treatment of 3a‐c and 4a‐f with Lewis acid, e.g. titanium(IV) chloride and tin(IV) chloride, caused migration of acyl groups to afford the corresponding 1‐acyl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones 5a‐c and 6a‐f. Interestingly, the reactions of 3‐acyloxypyrazoles 3e and 3f with tin(IV) chloride provided the corresponding tin(IV) complexes 8e and 8f.
Lewis acid catalyzed nenitzescu indole synthesis
Authors: Velezheva Valeriya S. , Kornienko Albert G. , Topilin Sergey V. , Turashev Ascar D. , Peregudov Alexander S. , Brennan Patrick J. 
Published: March 2009

Abstractmagnified imageA novel method for Lewis acid catalyzed Nenitzescu indole syntheses of 5‐hydroxyindoles bearing different substituents in positions 1 )Alk, Bn, Ar), 2 )Me, Et, Ph), and 3 )COOEt, COMe, CONHPh) as well as tricyclic derivatives are reported. The method is simple, rapid, efficient, and allows preparation of hydroxyindoles from 1,4‐benzoquinone and enamines in good to excellent yields with the use of low‐polar solvents in the presence of weak Lewis acids catalysts. The formation of 5‐hydroxyindoles under such mild conditions is explained in terms of a non‐redox mechanism.
Aromatization and ring cyclization: A reasonable understanding on the ring cyclization mechanism of 3‐amino‐6‐hydrazino‐1,2,4‐triazin‐5(2H)‐one reacted with one‐carbon fragment reagents or nitrous acid
Authors: Hwang Long‐Chih , Tus Chun‐Hsien , Wang Jung‐Hui 
Published: March 2009

Abstractmagnified imageThe cyclization mechanism for the title compound (2) reacting with one‐carbon fragment reagents or nitrous acid to afford heterobicyclic compounds 6‐amino‐3‐substituted‐1,2,4‐triazolo[3,4‐f][1,2,4]triazin‐8(7H)‐ones (3a∼d) or 6‐amino‐1,2,3,4‐tetrazolo[5,1‐f][1,2,4]triazin‐8(7H)‐one (4), respectively, is explored in this paper. When 3‐amino‐2‐benzyl‐6‐hydrazino‐1,2,4‐triazin‐5(2H)‐one (10), the N‐2 benzylated derivative of 2, is treated under the same conditions, ring cyclization does not occur; instead, 3‐amino‐2‐benzyl‐6‐substituted‐1,2,4‐triazin‐5(2H)‐ones (11,12,14) and 2‐N‐(2‐amino‐1‐benzyl‐4‐oxo‐1,2,4‐triazin‐5‐yl)semicarbazide (13) are formed. Alternatively, when 3‐amino‐6‐hydrazino‐2‐[(2‐hydroxyethoxy)methyl]‐1,2,4‐triazin‐5(2H)‐one (16), a compound bearing the 2‐[(2‐hydroxyethoxy)methyl] side‐chain at N‐2 of 2 by an NCO bond, reacts with glacial acetic acid or nitrous acid, the side‐chain is cleaved through acidolysis to affford the ring‐closed compound 6‐amino‐3‐methyl‐1,2,4‐triazolo[3,4‐f][1,2,4]triazin‐8(7H)‐one (3b) or compound 4, respectively. From these results, we suggest a cyclization mechanism that the ring cyclization is dependent on the aromatization of the 1,2,4‐triazine ring, which influence the reactivity and reaction behavior of the π‐deficient 1,2,4‐triazine.
One‐pot three‐component synthesis of 2‐substituted 4‐aminoquinazolines
Authors: Rad‐Moghadam Kurosh , Samavi Laleh 
Published: March 2009

Abstractmagnified imageA facile and rapid synthesis of the title compounds via one‐pot reaction of 2‐aminobenzonitrile, orthoesters and ammonium acetate under solvent‐free and microwave condition is described.
π‐Aryl/heteroaryl conjugated coumarin‐thiazoles: Synthesis, optical spectral and nonlinear optic properties
Authors: Mashraqui Sabir H. , Mistry Hitesh , Sundaram Subramanain 
Published: March 2009

Abstractmagnified imageA series of π‐aryl/heteroaryl conjugated coumarin‐thiazole systems 8a‐f has been synthesized by using Hantzsch thiazole protocol and Wittig olefination as the keys. In the UV‐Visible spectra of 8a‐f, a main absorption band associated with a dominant π‐π* transition is observed in the region of 338 to 390 nm. Qualitatively, the values of λmax have been found to correlate satisfactory with the donor/acceptor characteristics of the π‐attached chromophores. Marked changes observed in the absorption maxima of 8a under acidic conditions are rationalized on the basis of mono‐or bis‐protonation and modification of the donor/acceptor properties of chromophores undergoing protonation. The emission spectra of 8a‐f, obtained by exciting the molecules at their main absorption bands showed emission maxima in the region of 429 nm to 537 nm, with relatively high Stokes shifts of 145 and 171 nm being observed for 8a and 8e, carrying a π‐donor, dimethylaminophenyl and a π‐acceptor, p‐nitrophenyl chromophore, respectively. Although, the first hyperpolarisability β, measured by the hyper‐Reileigh scattering (HRS) technique are modest (12 to 23 × 10−30 esu), all the compounds exhibited complete transparency in the frequency doubling region at 532 nm and showed high thermal stability (Td from 330 to 365 °C).