bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 2′‐amino‐17‐cyclopropylmethyl‐6,7‐dehydro‐3,14‐dihydroxy‐4,5α‐epoxy‐6,7:4′,5′‐thiazolomorphinan from naltrexone
Authors: Nan Yang , Xu Wei , Zaw Kyaw , Hughes Kathrine E. , Huang Liang‐Fu , Dunn William J. , Bauer Ludwig , Bhargava Hemendra N. 
Published: April 2009

AbstractFusion of an azole moiety at C‐6 and C‐7 of naltrexone (1) is illustrated by the synthesis of the title compound8. Bromination of 3‐O‐methylnaltrexone led to the 1,7α‐dibromo derivative which reacted with thiourea to attach the 2‐aminothiazole ring to C‐6 and C‐7 of naltrexone. After converting the amino and alcohol groups to trimethylsilyl derivatives, the aromatic bromo group was removed by halo‐lithium interchange with butyllithium, followed by hydrolysis with water. In the final step of the synthesis, the methyl ether was cleaved by boron tribromide to generate8. An alternate synthesis of8commenced with 3‐O‐acetylnaltrexone (9). Bromination of9in acetic acid in the presence of hydrobromic acid produced a mixture of 3‐O‐acetyl‐7α‐bromonaltrexone (10) and 7α‐bromonaltrexone (11), both, as hydrobromides. Reaction of this mixture with thiourea furnished8(62% from1). While1H and13C chemical shifts of all compounds are reported, those of11hydrobromide and8dihydrochloride were established unequivocally.
Saturated heterocycles, 248. Synthesis of 2,4‐dioxo and 4‐oxo‐2‐thioxo derivatives of octahydrocyclopenta[d]pyrimidines
Authors: Fülöp Ferenc , Szakonyi Zsolt , Bernáth Gábor , Sohár Pál 
Published: April 2009

AbstractUnsubstituted and 1‐benzyl‐substituted cis‐cyclopenta[d]pyrirnidine‐2,4‐diones and cis‐2‐thioxo‐cyclopenta[d]pyrimidin‐4‐ones 9a,b and 10a,b were prepared from the corresponding cis‐2‐amino‐1‐cyclopentanecarboxylates 3 and 5 with potassium cyanate and thiocyanate. It was found that the cis derivatives 7a‐h readily underwent ring closure, resulting in 3‐substituted cis‐2,4‐cyclopenta[d]pyrimidinediones and cis‐2‐thioxocyclopenta[d]pyrimidin‐4‐ones 11a‐d and 12a‐d, whereas the trans counterparts 8a‐d failed to cyclize, but gave hydrolysed amino acid derivatives 13a,b and 14. This difference in the reactivities of the cis and trans isomers is a further example of the difficulty of preparing cyclopentane trans‐fused six‐membered 1,3‐heterocycles by ring closure.
Pyrrolothieno[1,4]diazepines. Part V. Study of their chemical reactivity and first synthesis of oxazino[4,3‐c]pyrrolo[1,2‐a]thieno[2,3‐f] [1,4]diazepines
Authors: Boulouard Michel , Dallemagne Patrick , Rault Sylvain 
Published: April 2009

AbstractThe study of the chemical reactivity of methyloxopyrrolothienodiazepinones led to new derivatives such as oximes, methyloximes, hydrazones and alcohols and also, according to an intramolecular cyclization, to new oxazino[4,3‐c]pyrrolo[1,2‐a]thieno[3,2‐f][1,4]diazepines.
Studies on methoxylation in the 7H‐naphtho[1,2,3‐I,j][2,7]naphthyridin‐7‐one system
Authors: Zjawiony Jordan K. , Kbalil Ashraf A. , Clark Alice M. , Hufford Charles D. , Buolamwini John K. 
Published: April 2009

AbstractStudies on methoxylation in the 7H‐naphtho[1,2,3‐i,j][2,7]naphthyridin‐7‐one (sampangine) system represented by 3‐bromo‐ and 4‐bromosampangine as well as sampangine itself are described. We have found that regioselectivity of nucleophilic substitution in the sampangine system can be directed by reaction conditions. Under kinetic control (lower temperatures) substitution at C‐4 is the predominant reaction, regardless of whether 3‐bromo or 4‐bromosampangine were used. At higher temperatures, when the reaction is thermodynamically controlled, substitution of the bromine atom at C‐3 predominates. This is the first reported example of nucleophilic substitution in ring A of the 7H‐naphtho[1,2,3‐i,j][2,7]naphthyridin‐7‐one system.
Selective synthesis of some 5‐hydrazono‐5,6,7,8‐tetrahydro‐2H‐1‐benzopyran‐2‐ones
Authors: Trebše Polonca , Recelj Boris , Kočevar Marijan , Polanc Slovenko 
Published: April 2009

AbstractA simple, highly selective transformation of 5,6,7,8‐tetrahydro‐2H‐1‐benzopyran‐2,5‐diones 1–3 and 14 with some phenylhydrazines and heterocyclic hydrazines to 5‐hydrazono‐2H‐1‐benzopyran‐2‐ones 4–12 and 15–16 is described. Under more severe conditions the hydrazonoquinoline derivative 17 was obtained from the benzopyran derivative 3 and Phenylhydrazine.
Synthesis of 2‐[mercapto(cyano)methylene]‐1,2,3,4‐tetrahydro‐quinazolin‐4‐ones and 2‐amino‐4‐methylpyrazolo‐[1,5‐a]quinazolin‐5(4H)‐one
Authors: Fleischer Judit , Takács Kálmán , Hermecz István 
Published: April 2009

AbstractA series of 2‐[mercapto(cyano)methylene]‐1,2,3,4‐tetrahydroquinazolin‐4‐ones and 2‐amino‐4‐methylpyrazolo[1,5‐a]quinazolin‐5(4H)‐one were prepared from 2‐cyanomethylquinazolin‐4(3H)‐ones via α‐bromo derivatives 4 and amide oxime 8, respectively. The new compounds have been characterized by elemental analyses and 1H‐nmr, in some cases by ir and 13C‐nmr investigations.
Lewis acid assisted reactions of N‐(α‐ aminoalkyl)benzotriazoles and unactivated alkenes for the facile synthesis of 4‐, 2,4‐, and 3,4‐substituted 1,2,3,4‐tetrahydroquinolines
Authors: Katritzky Alan R. , Nichols Daniel A. , Qi Ming , Yang Baozhen 
Published: April 2009

AbstractA range of substituted tetrahydroquinolines have been synthesized from benzotriazole derivatives and unactivated alkenes in the presence of a Lewis acid. These reactions utilize readily available starting materials and mild reaction conditions, and give high yields. The reaction mechanisms are discussed.
Synthesis of 2‐(4‐quinazolinyl)ethyl sulfides via addition of thiols to 4‐vinylquinazolines
Authors: Samaritoni Jack G. , Babbitt George E. 
Published: April 2009

AbstractReaction of vinyl and isopropenyl Grignard reagents with quinazoline results in addition to the 3,4‐imine bond to give the 4‐alkenyldihydroquinazolines 4 which are conveniently aromatized with potassium ferri‐cyanide to the 4‐alkenylquinazolines 5. Quinazolines 5 undergo addition with thiols under neutral conditions to afford the quinazolinylethyl sulfides 2 in moderate yields.
Fused 1,2,4‐triazole heterocycles. IV. Synthesis of four new heterocyclic ring systems of [1,2,4]triazolo[1,3]thiazinoquinolines
Authors: Kóródi Ferenc , Jekõ József , Szabó Zoltán 
Published: April 2009

AbstractSyntheses of 5H‐[1,2,4]triazolo[5′,1′:2,3][1,3]thiazino[5,4‐c]quinolines 8, 5H‐[1,2,4]triazolo[3′,4′:2)3][1,3]thiazino[5,4‐c]quinolines 9, 5H‐[1,2,4]triazolo[5′,1′:2,3][1,3]thiazino[5,6‐c]quinolines 14 and 5H‐[1,2,4]triazolo[3′,4′:2,3][1,3]thiazino[5,6‐c]quinolines 15 are described starting from 4‐chloro‐3‐chloromethylquinaldine (4) and 1,2,4‐triazole‐5‐thiols 5 taking advantage of different reactivity of the chlorine atoms of 4 under different reaction conditions. The structures of products 8, 9, 14 and 15 and the intermediates leading to them were confirmed by desulfurization, unequivocal syntheses and nmr spectroscopy as well.
On the formation and reactivity of N(2),N(2′)‐tetrasubstituted 2,4‐diamino‐5‐(2‐amino‐4‐thiazolyl)thiazoles
Authors: Flaig Ronald , Hartmann Horst 
Published: April 2009

AbstractBy the reaction of weak bases with N(2)‐disubstituted 2‐amino‐4‐thiazoliniminium chlorides 3, easily available by the reaction of thioureas 1 with α‐chloroacetonitrile 2, N(2),N(2′)‐persubstituted 2,4‐diamino‐5‐(2‐amino‐4‐thiazolyl)thiazoles 8 are formed. These new bis‐thiazoles react, as exemplified with the dimorpholino derivative 8a, with different electrophilic reagent, such as phenyl isothiocyanate 9, 4‐nitro‐phenyldiazonium salt 11, or 4‐dialkylaminobenzaldehydes 13 at their 5H‐substituted thiazole moieties to give the corresponding thioanilides 10, azo compounds 12, and methine dyes 14, respectively. With sodium nitrite and the Vilsmeier reagent the thiazole 8a is transformed, via unstable intermediates, into the tricyclic 2,7‐dimorpholinothiazolo[4,5‐c]thiazolo[4,5‐e]pyridazine 16 and 2,7‐dimorpholinothiazolo[4,5‐b]thiazolo[4,5‐d]pyridine 19, respectively.
Ketene dithioacetal derivatives of 1‐phenyl‐3,5‐dioxopyrazolidine. Synthesis and NMR characterization
Authors: Molinari Aurora , Oliva Alfonso , Sánchez Lucá , Feliciano Arturo San 
Published: April 2009

Abstract1‐Phenyl‐3,5‐dioxopyrazolidine 1 reacts with carbon disufide and alkyl halides in presence of excess of sodium acetate in dimethylformamide to afford the ketene dithioacetals 3a‐h. The 13C chemical shift assignments of these compounds were made on the basis of two‐dimensional nmr studies performed on the N‐methylketene dithioacetal derivative 4.
Synthesis of N‐α‐styrylcyclopropane‐5‐phenylamino‐1,2,4‐triazoles and their conversion to γ‐butyrolactones
Authors: Lee Kee‐Jung , Kim Dong‐Wook 
Published: April 2009

AbstractThe reaction of cyclopropyl phenyl ketone 1‐ureidoethylidenehydrazones 14 with a mixture of tri‐phenylphosphine, carbon tetrachloride, and triethylamine provides a general route to N‐α‐styrylcyclo‐propane‐5‐phenylamino‐1,2,4‐triazoles 17 via the thermal reaction of the expected azinocarbodiimide intermediates 15, and the oxidation of 17 with 3‐chloroperoxybenzoic acid affords 1,2,4‐triazole substituted y‐butyrolactones 23 directly.
The synthesis of pyrazolo[1,2‐a]pyrazoles. Regio‐ and stereo‐selective 1,3‐dipolar cycloadditions of (1Z)‐rel‐(4R,5R)‐1‐arylmethylene‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinon‐1 ‐azomethinimines
Authors: Svete Jurij , Prešeren Andrej , Stanovnik Branko , Golič Ljubo , Golič‐Grdadolnik Simona 
Published: April 2009

AbstractReaction of rel‐(4R,5R)‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinone (4) with aromatic aldehydes 5a‐f gave the corresponding (1Z)‐rel‐(4R,5R)‐1‐arylmethylene‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinon‐1‐azomethinimines 6a‐f. 1,3‐Dipolar cycloadditions of azomethinimines 6a‐f to various dipolarophiles, which were found to proceed regio‐ and stereo‐selectively, afforded the corresponding pyrazolo[1,2‐a]‐pyrazoles 8a‐f, 10, and 13–16. Reaction of azomethinimine 6a with hydrogen cyanide gave rel‐(5R,6R)‐6‐benzoylamino‐5,6‐dihydro‐3,5‐diphenyl‐1‐oxo‐1H,7H‐pyrazolo[1,2‐a][1,2,3]triazole (18) as a representative of a new ring system.
Synthesis of 1‐alkyl‐2,3‐dihydro‐2‐(4‐pyridinyl)‐1H‐isoindoles as potential selective serotonin reuptake inhibitors
Authors: Kapples Kevin J. , Shutske Gregory M. 
Published: April 2009

AbstractTwo 2,3‐dihydro‐2‐(4‐pyridinyl)‐1H‐isoindoles 2a,b have been synthesized by the reaction of isoindoline with 4‐chloropyridines. In addition, a number of 1‐alkyl‐2,3‐dihydro‐2‐(4‐pyridinyl)‐1H‐isoindoles 2c‐h were obtained from 2‐(4‐pyridinyl)phthalimide (5). The addition of alkyl Grignard reagents to 5 gave 1‐alkylhydroxyisoindolones 6a‐f which, in two cases 6a,b, were dehydrated and subjected to three separate reductions to give targets 2c,d. In three cases, the intermediate hydroxyisoindolones 6c‐e were reduced in one step to the target compounds 2c‐g with lithium aluminum hydride‐aluminum chloride. When 6f, the product of the addition of phenyl Grignard to 5, was subjected to these conditions, a hydroxyisoindoline 7 was obtained which was further reduced to 2h with triethylsilane‐trifluoroacetic acid. The lithium aluminum hydride‐aluminum chloride conditions were successfully applied to the synthesis of a 1‐benzyl‐4‐piperidine derivative 21.
Conformational analysis of novel monoaryl substituted protoporphyrins by 1D NOE, 2D NOESY and molecular modeling studies
Authors: Robinsohn Adriana E. , Buldain Graciela Y. , Maier Marta S. 
Published: April 2009

AbstractPorphyrins 1–4 are monoaryl protoporphyrins substituted on C‐5 or C‐15 by a phenyl group. One‐ and two‐dimensional nOe experiments and molecular modeling studies allowed us to find the most favorable conformations for these compounds. In the four porphyrins, the exocyclic phenyl group adopts a non‐coplanar disposition relative to the plane of the macrocycle and this is reflected in the ID nOe difference and 2D NOESY results. In porphyrins 1 and 3 the macrocycle is nearly planar while nonplanar saddle conformations were obtained for porphyrins 2 and 4.
Synthesis of new fluorinated 1,5‐benzoxazepine derivatives
Authors: Cocco Maria Teresa , Congiu Cenzo , Onnis Valentina , Bernard Angela Maria , Piras Pier Paolo 
Published: April 2009

AbstractA simple approach to the fluorinated 1,5‐benzoxazepine ring system is described. By reacting commercially accessible aminophenols 1 and the trifluoroacetylvinyl ether 2, high yields of enaminones 3 were obtained. Functionalization of methyl group of compounds 3 gave rise to dieneamines 4 that were cyclized in acidic environment to benzoxazepine derivatives 5.
On the preparation of substituted 4H‐ 1,3,4‐thiadiazolo[2,3‐c]‐1,2,4‐triazin‐4‐ones and 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazoles
Authors: Coppo Frank T. , Fawzi Maged M. 
Published: April 2009

AbstractThe reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4‐amino‐4,5‐dihydro‐3‐(methylthio)‐1,2,4‐triazin‐5‐ones in acetonitrile gave several substituted 4H‐1,3,4‐thiadiazolo[2,3‐c]‐1,2,4‐triazin‐4‐ones VIa‐h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4‐amino‐3‐(methylthio)‐5‐(trifluoromethyl)‐4H‐1,2,4‐triazole to give the benzoyl thiourea IX and with 4‐amino‐3‐mercapto‐5‐(trifluoromethyl)‐4H‐1,2,4‐triazole to give the bicyclic compound N‐[3‐(trifluoromethyl)‐1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazol‐6‐yl]benzamide IX.
Synthesis and exchange reactions of 5‐alkyl‐2‐oxo‐6‐thioxo‐1,2,3,6‐hexahydropyrimidine‐4‐carboxylic acids
Authors: Batty Craig A. , Manthey Michael K. , Kirk Julie , Manthey Monika , Christopherson Richard I. , Hambley Trevor 
Published: April 2009

AbstractAn improved preparation of 2‐oxo‐6‐thioxo‐1,2,3,6‐hexahydropyrimidine‐4‐carboxylic acid 3, a potent inhibitor of dihydroorotase is presented. Trans‐5‐alkyl‐2‐oxo‐6‐thioxohexahydropyrimidine‐4‐carboxylic acids 12a‐c were synthesised via the thiation of the p‐methoxybenzyl esters of 5‐alkyldihydroorotic acids with Lawesson's reagent followed by subsequent de‐protection. The corresponding cisisomers were prepared by reduction of 5‐alkyl‐6‐thioxoorotic acids with zinc in acetic acid. The stability and exchange reactions of 12a‐c under physiological conditions were investigated by ultra‐violet and 1H nmr spectroscopy. The attempted synthesis of 16, a fused cyclopentyl derivative of 3 is also presented.
Synthesis of 5‐(1‐azido‐2‐haloethyl)arabinouridines
Authors: Kumar Rakesh , Wiebe Leonard I. , Knaus Edward E. 
Published: April 2009

AbstractA novel class of 5‐(1‐azido‐2‐haloethyl)arabinouridines 4–6 was synthesized by the regiospecific addition of halogenoazides (XN3: X = C1, Br, I) to the vinyl substituent of 5‐vinylarabinouridine (7). The title 5‐(1‐azido‐2‐haloethyl)arabinouridines 4–6 were previously shown to exhibit significant in vitro antiviral activity against herpes simplex virus type 1, varicella zoster virus and cytomegalo virus.
Palladium‐catalyzed synthesis of 3‐(alkylamino)isoindolin‐1‐ones by carbonylative cyclization of 2‐bromobenzaldehyde with primary amines
Authors: Cho Chan Sik , Jiang Li Hong , Lee Dong Yub , Shim Sang Chul , Lee Hyung Soo , Cho Sung‐Dong 
Published: April 2009

Abstract2‐Bromobenzaldehyde reacts with an excess of primary amines under a carbon monoxide in the presence of a catalytic amount of bis(triphenylphosphine)palladium(II) chloride together with triethylamine to give the corresponding 3‐(alkylamino)isoindolin‐1‐ones in good yields.
A short and unequivocal synthesis of 5‐aminotetrazolo[1,5‐a]‐quinazoline as a tricyclic analogue of 4‐(3‐bromoanilino)‐6,7‐dimethoxyquinazoline (PD 153035)
Authors: Bencteux Edith , Houssin Raymond 
Published: April 2009

AbstractThe discovery of 4‐(3‐bromoanilino)‐6,7‐dimethoxyquinazoline (PD 153035) as an extremely potent inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor led to the preparation of several fused tricyclic quinazoline analogues. The present paper reports a new tricyclic derivative: 5‐(3‐bromoanilino)‐7,8‐dimethoxytetrazolo[1,5‐a]quinazoline. This compound was synthesized by two different pathways viaa 1,3‐dipolar cycloaddition of an azide at carbon 2 of the quinazoline ring.
Synthesis of 1,2,3‐triarylpyrroles from 1‐benzylbenzotriazoles via [1 + 2 + 2] annulation
Authors: Katritzky Alan R. , Wang Zouquan , Li Jianqing , Levell Julian R. 
Published: April 2009

Abstract1,2,3‐Triarylpyrroles 7 have been synthesized by sequential lithiation and alkylation of 1‐benzylbenzo‐triazoles 1 with 2‐bromoacetaldehyde diethyl acetal (2) and N‐benzylideneaniline (4), followed by treatment with formic acid in ethanol.
Investigation of azoxides and olefins [3 + 2] cycloaddition to 1,2,3‐oxadiazolidines by a combination of density functional theory and semiempirical methods
Authors: Jursic Branko S. 
Published: April 2009

AbstractTheoretical studies of the aspects of an azoxide addition to olefins is presented. The stability of the 1,2,3‐oxadiazolidine ring is discussed in regard to its capability to undergo a retro cycloaddition reaction. The structural features necessary to increase the stability of the heterocycle is proposed and evaluated. The computational results are supported with experimental observations.
Average deviation from ideal bond order as a measure for aromaticity. AMI commuted aromatic properties of five‐membered C4H4X ring systems
Authors: Jursic Branko S. 
Published: April 2009

AbstractAverage bond order deviation from that in an ideal aromatic system was proposed as a parameter for evaluation of aromaticity in general. The validity of this approach was examined by studying a series of aromatic five‐membered heterocycles. The geometries and bond orders were computed with AM1 semiem‐pirical method. The usefulness of AM1 semiempirical method for computation of these parameters was also discussed.
3,3,3‐Trifluoro‐2,2‐dihydroxypropanesulfonamides as building blocks for trifluoromethyl‐containing pyrazoles and benzimidazoles
Authors: Takahashi Masahiko , Muta Shigeru , Nakazato Hiroshi 
Published: April 2009

Abstract1‐Alkyl‐3‐trifluoromethylpyrazole‐4‐sulfonamides 10, (2‐trifluoromethyl‐2,3‐dihydrobenzimidazol‐2‐yl)methanesulfonamides 12, and (2‐benzimidazolyl)metbanesulfonamides 13 were prepared starting from 3,3,3‐trifluoro‐2,2‐dihydroxypropanesulfonamides 1.
Synthesis of C‐5 benzoyl and azido functionalized 2,2′‐dithiobis‐and 2,2′‐diselenobis(1H‐indoles)
Authors: Sun Li , Rubin J. Ronald , Kraker Alan J. , Showalter H. D. Hollis 
Published: April 2009

AbstractNovel methods for the synthesis of C‐5 benzoyl and azido analogues of 2,2′‐dithiobis(1H‐indole), 1, and 2,2′‐diselenobis(1H‐indole), 2, are described to further explore the structure activity relationships in this region of the molecule. Analogues 3‐i displayed inhibitory activity (IC50 = 0.45‐2.03 μ) toward the catalytic domain of the epidermal growth factor receptor tyrosine kinase that was equivalent to or better than that of unsubstituted compounds 1 and 2. The regiochemistry of Friedel‐Crafts benzoylation onto 1 was determined by X‐ray crystallography. To test the potential for compounds of this class to interact with the epidermal growth factor receptor tyrosine kinase via a sulfhydryl exchange mechanism, reaction of a 2,2′‐dithiobis(1H‐indole) with glutathione was carried out and the product characterized.
Synthesis and characterization of some heterocyclic derivatives by cyclization of carbohydrate thiosemicarbazones. Part I
Authors: Alho M. A. Martins , Accorso N. B. D' 
Published: April 2009

AbstractWe report the synthesis of 2,3‐dihydro‐1,3,4‐thiadiazoles and 1,3,4‐thiadiazoles from 1,2:3,4‐di‐O‐iso‐propylidene‐α‐D‐galacto‐1,6‐hexodialdo‐1,5‐pyranose thiosemicarbazone. The physical and spectro‐scopic characterizations of the heterocyclic derivatives as well as the intermediate product are described. We present the prefered conformation in solution using computational calculations and spectroscopic data. The possibilities of chiral induction of the cyclization reaction are discussed.
Synthesis of substituted 3‐amino‐4‐cyano‐1‐oxo‐1,2,5,10‐tetrahydroazepino [3,4‐b]indoles
Authors: Troschütz Reinhard , Hoffmann Annin 
Published: April 2009

AbstractThe preparation of 3‐amino‐ and 3‐dialkylamino‐4‐cyanoazepino[3,4‐fc]indoles bearing substituents on the aromatic nucleus and N10 is outlined. Starting from suitable substituted ethyl 3‐formylindole‐2‐carboxy‐latcs 2, condensation with malononitrile (3) and subsequent sodium borohydride‐reduction yielded ethyl 3‐(2,2‐dicyanoethyl)indole‐2‐carboxylates 5 and 19, respectively, which were cyclized in boiling alkoxides to 3‐alkoxy‐4‐cyanoazepino[3,4‐b]indoles 10,11,20 and 21. This sequence constitutes a novel and flexible route to functional azepino[3,4‐b>]indoles. The aminolysis of 10,11,20 and 21 with different amines and ammonia yielded the title compounds which were screened for their possible biological activity.
A study of the behaviour of 2,4‐substituted thiosemicarbazides toward orthoesters: Formation of mesoionic compounds
Authors: Buccheri Francesco , Cusmano Giuseppe , Gruttadauria Michelangelo , Noto Renato , Werber Giuseppe 
Published: April 2009

AbstractThe reactions beetwen 2,4‐disubstituted thiosemicarbazides and orthoesters in refluxing xylene led to the formation of the 1,2,4‐triazoline‐5‐thione ring and to the 1,2,4‐triazolium‐5‐thiolate ring. The formation of the mesoionic componds is due to rearrangement of the easily available 2,4‐disubstituted thiosemicarbazides to 1,4‐disubstituted thiosemicarbazides under the reaction conditions adopted. This method can be usefully used for the synthesis of mesoionic compounds, especially in the case of the 2‐methyl‐4‐phenylthiosemicarbazide.
Reactivity of p‐phenyl substituted β‐enamino compounds using K‐10/ultrasound. I. Synthesis of pyrazoles and pyrazolinones
Authors: Valduga Claudete J. , Braibante Hugo S. , Braibante Mara E. F. 
Published: April 2009

AbstractThe reactivity of the β‐enamino ketones, 3‐amino‐1‐(p‐phenyl‐substituted)‐2‐buten‐1‐ones 1a‐d and β‐enamino esters, ethyl 3‐amino‐3‐(p‐phenyl‐substituted)‐2‐propenoates 5a‐d was systematically studied when allowed to react with hydrazine and methylhydrazine under solid support K‐10/ultrasound conditions and in homogeneous media (reflux in ethanol or dichloromethane). The products were pyrazoles 2a‐d, N‐methylpyrazoles 3a‐d, 4a‐d and N‐methylpyrazolinones 6a‐c and 7a‐c. The regiochemistry of the cyclization reactions showed dependence upon the reaction conditions employed as well as upon the sub‐stituent in the aromatic ring.
An expeditious procedure for the synthesis of purines from aminoimidazolecarbaldehydes
Authors: Perandones Francisco , Soto José L. 
Published: April 2009

AbstractReactions of 4‐amino‐1,2‐dimethylimidazole‐5‐carbaldehyde (1) and 5‐amino‐1‐methylimidazole‐4‐car‐baldehydes 3 with nitriles, in the presence of dry hydrogen chloride afforded to the formation of purine derivatives. This constitutes a facile and versatile one‐pot synthesis of purines. The use of formamide instead of nitriles leads to the respective purines without substituents on the pyrimidine ring, 2d and 4e,f.
A ring opening reaction of benzisothiazolones. A new route to unsymmetrical disulfides
Authors: Sanchez Joseph P. 
Published: April 2009

AbstractA series of unsymmetrical disulfides has been prepared by employing a reaction involving a ring opening, nucleophilic attack of a thiol on a 1,2‐benzisothiazol‐3‐one. The benzisothiazolones were in turn prepared by an intramolecular ring closure of an amide on a sulfenyl thiocarbonate. The sulfenyl esters were synthesized as intermediates for preparing mixed‐disulfides, but the benzisothiazolone ring closure occurred spontaneously. It was initially thought that the mixed‐disulfides were being formed from the sulfenyl ester, but the isolation and stepwise reaction of the benzisothiazolones provided proof for the reaction mechanism.