bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compounds in the pyrrolo[3′,4′:4,5] pyrrolo[3,4‐b]indole series
Authors: Yevich Joseph P. , Murphy John R. , Dufresne Richard F. , Southwick Philip L. 
Published: April 2009

AbstractCompounds in the new pyrrolo[3′,4′:4,5]pyrrolo[3,4‐b]indole series have been produced by an imide cyclization of appropriate derivatives of pyrrolo[3,4‐b]indole.
Ring transformation of 6‐methyl‐3,4‐dihydro‐2H‐1,3‐oxazine‐2,4‐diones
Authors: Kato Tetsuzo , Izumi Uichiro , Katagiri Nobuya 
Published: April 2009

AbstractRing transformation of 6‐methyl‐3,4‐dihydro‐2H‐1,3‐oxazine‐2,4‐dione (Ia) and its N‐sub‐stituted derivatives, such as 3‐methyl (Ib), 3‐ethyl (Ic), and 3‐benzyl (Id) derivatives is described. Reaction of Ia with hydrazine hydrate gave 1‐amino‐6‐methyluracil (II), while Id reacted with hydrazine hydrate to give 3‐hydroxy‐5‐methylpyrazole (III). Reaction of Ia,b,d with ethyl acetoacetate in ethanol in the presence of sodium ethoxide afforded ethyl 3‐acetyl‐6‐hydroxy‐4‐methyl‐2(1H) pyridone‐5‐carboxylate derivatives (IVa,b,d). On the other hand, reaction of Ib,c,d with ethyl acetoacetate in tetrahydrofuran in the presence of sodium hydride did not give IV, but gave 3‐acetyl‐1‐alkyl‐5‐(N‐alkylcarbamoyl)‐6‐hydroxy4‐methyl‐2(1H) pyridone (VIb,c,d). Mechanisms for the formation of compounds IV and VI are discussed.
Chemical investigations of citraconimide
Authors: Earl Robert A. , Clough Fred W. , Townsend Leroy B. 
Published: April 2009

AbstractThe chemical reactivity of citraconimide (3‐methylmaleimide, 2) has been investigated with special emphasis being placed on the use of mild and selective reaction conditions. Particular attention has been focused on the theiotropic reactivity of citraconimide. The results indicate that the reaction of various mercaptans with citraconimide is highly regioselective resulting predominately in the geminally substituted products with the percentage of vicinally substituted products increasing as a function of the steric bulk of the alkyl mercaptan. Additional studies on the double bond of citraconimide have furnished 4‐halogeno‐ and the 3,4‐dihydro derivatives of citraconimide. Several N‐substituted citraconimide derivatives have also been prepared.
Synthèse et tautoméric d'amino‐3 et d'hydroxy‐3 buténolide
Authors: Payard Marc , Paris Joelle , Tronche Pierre 
Published: April 2009

AbstractLa synthèse d'amino‐3 et d'hydroxy‐3 méthyl‐2 cyclohexane spiro‐4,4 butène‐2 olide‐4 est effectuée au depart d'isocyanate ou de précurseur d'isocyanate. Les structures tautomères étudiées à l'aide des spectres ir et de rmn et par la réactivité des groupements fonctionnels sont discutées.
An improved preparation of tetrahydropyridines from 1‐alkyl‐3‐acylpyridinium salts
Authors: Chevolot L. , Husson H.‐P. 
Published: April 2009

AbstractThe hydrogenation of 1‐alkyl‐3‐acylpyridinium salts in methanol in the presence of 10% palladium‐charcoal/disodium hydrogen phosphate‐sodium dihydrogenphosphate suspension leads to the corresponding tetrahydropyridines. This represents an improvement over the Wenkert method.
Direct sulfhydrolysis of cyclic AMP: A one‐step synthesis of the cyclic ribonucleotide of 6‐mercaptopurine
Authors: Meyer Rich B. , Stone Thomas E. , Heinzel Frederick P. 
Published: April 2009

AbstractTreatment of adenosine cyclic 3′,5′‐phosphate with liquid H2S in aqueous pyridine provided a convenient, one‐step synthesis of 9‐β‐D‐ribofuranosylpurine‐6(1H) thione cyclic 3′,5′‐phosphate.
1,3,4‐Thiadiazoles. XI. Synthesis and behaviour of 4‐Alkyl‐5‐acyl‐1,3,4‐thiadiazolines
Authors: Alemagna Andreina , Bacchetti Tullio 
Published: April 2009

AbstractThe synthesis of the title compounds from thiadiazolium salts and aldehydes, and their behaviour towards some nucleophiles and aldehydes are described.
Reaction of diethyl acetonedicarboxylate with nitrosyl chloride
Authors: Silverman Richard B. 
Published: April 2009

AbstractThe reaction of diethyl acetonedicarboxylate with greater than two equivalents of nitrosyl chloride or the reaction of diethyl isonitrosoacetonedicarboxylate with one equivalent of nitrosyl chloride gave diethyl 4‐hydroxyisoxazole‐3,5‐dicarboxylate in quantitative yield. Mechanistic possibilities are discussed.
Direct oxidation of a heterocyclic nitroso dimer
Authors: Bozzi Edward G. , Clapp Leallyn B. 
Published: April 2009

AbstractA cyclic cis‐nitroso dimer, 3,4‐dibromo‐3,5,5‐trimethylpyrazoline 1,2‐dioxide was oxidized directly to an open chain 1,3‐dinitro compound by a peroxyacid but nitrosyl chloride displaced bromine, added, and oxidized the same compound to 3‐chloro‐4‐nitro‐3,5,5‐trimethylpyrazoline 1,2‐dioxide.
Polymorphism in the 2‐(4‐morpholinothio) benzothiazole
Authors: Guzman J. , Largo‐Cabrerizo J. 
Published: April 2009

AbstractThe existence of two conformational isomers (A and B) with different crystal structures in 2‐(4‐morpholinothio) benzothiazole is shown. The melting temperatures of the two conformers are 345° and 357° K, respectively. The difference between the values of the melting enthalpies and entropies gives an indication of the two isomers flexibility whose proportion depends on the thermal history of the sample.
Reactivity of the A‐CH=N‐NR‐CX‐B system: 1,3,4‐Oxadiazoles
Authors: Werber Giuseppe , Buccheri Francesco , Noto Renato , Solazzo Vittorio 
Published: April 2009

AbstractA number of 5‐alkyl(or aryl)‐amino‐1,3,4‐oxadiazole‐2‐carboxyalkylesters have been prepared.
A new method of synthesis of some 2‐aryl and 2‐heterocyclic benzimidazole, benzoxazole and benzothiazole derivatives
Authors: Cohen Victor Israel 
Published: April 2009

AbstractA new one‐step facile method for the synthesis of some benzimidazole, benzoxazole and benzothiazole derivatives is described. The method involves the action of aromatic and heterocyclic selenoamides on some o‐phenylenediamine, o‐aminophenol and o‐aminothiophenol and their derivatives.
Reaction of ketenes with N,N‐disubstituted α‐aminomethyleneketones VIII. Synthesis of N,N‐disubstituted 4‐amino‐3‐chloro‐6‐phenyl‐2H‐pyran‐2‐ones
Authors: Bargagna Alberto , Schenone Pietro , Evangelisti Filippo 
Published: April 2009

AbstractThe dipolar 1,4‐cycloaddition of dichloroketene to N,N‐disubstituted 3‐amino‐1‐phenyl‐2‐propene‐1‐onesled directly to N,N‐disubstituted 4‐amino‐3‐chloro‐6‐phenyl‐2H‐pyran‐2‐ones only in the case of an usual aliphatic N,N‐disubstitution. In the case of partial or full aromatic N‐substitution, N,N‐disubstituted 4‐amino‐3,3‐dichloro‐3,4‐dihydro‐6‐phenyl‐2H‐pyran‐2‐ones were instead obtained, which were dehydrochlorinated with DBN to the corresponding 4‐amino‐3‐chloro‐6‐phenyl‐2H‐pyran‐2‐ones.
Azo coupling of benzenesulfonylhydrazones of heterocyclic aldehydes
Authors: Shawali A. S. , Fahmi A. A. , Eweiss N. F. 
Published: April 2009

AbstractThe reaction of aldehyde phenylsulfonylhydrazones (VII‐XI) with diazotized aromatic and heterocyclic primary amines gave the tetrazoles (XIV‐XIX). The yield of the tetrazoles was found to depend to some extent on the nature of the substituent present in the aldehyde moiety. The structures of the tetrazoles obtained was established on the basis of their analytical and spectral data. A tentative explanation for their formation is proposed. The acid dissociation constants of the tetrazoles (XIV) were also determined.
The synthesis of a pyrido[3,4‐d]pyrimidine analog of pteroic acid
Authors: Maguire James H. , Mckee Robert L. 
Published: April 2009

AbstractA multistep synthesis of ethyl 5‐amino‐2‐methyIpyridine‐4‐carboxylate (5a) starting from ethyl acetopyruvate and nitroacetamide is described. The condensation of 5a with benzoylcyanamide gave 2‐amino‐3‐benzoyl‐6‐methylpyrido[3,4‐d]pyrimidin‐4(3H) one (10), which could be hydrolyzed in alkali to give 2‐amino‐4‐hydroxy‐6‐methylpyrido[3,4‐d]pyrimidine (9). Free radical bromination of 10 in bromotrichloromethane gave a mixture of the bromo‐ and chloromethyl‐ derivatives (11). Fusion of 11 with ethyl p‐aminobenzoate, followed by alkaline hydrolysis gave the corresponding pteroic acid analog (12).
Reactivity of the A‐CH=N‐NR‐CX‐B system. 4‐Methyl‐5‐hydroxy‐5‐phenyl‐(or thienyl)‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐3‐ones and their ring contraction products
Authors: Werber Giuseppe , Buccheri Francesco , Vivona Nicolò , Bianchini Rosangela 
Published: April 2009

AbstractThe behaviour of some monosemicarbazones of phenyl‐ (1a‐c) and thienyl‐glyoxal (2a‐c) towards cyclizing agents has been investigated. Upon aqueous sodium hydroxide treatment, 4‐melhyl‐semicarbazones 1a and 2a gave the addition products 3 and 4, respectively, whereas the 2‐methyl‐ and 2,4‐dimethyl derivatives 1b,c and 2b,c gave demolition products only. On the other hand, compounds 1b,c gave the addition product 8 and the triazine 7, respectively, on treatment with aqueous hydrochloric acid.Bromination of 1a,b gave the bromosemicarbazone 10a and a mixture of 10b and 9, respectively. Performing the same reaction on 3 and 4 at 115°, the 1,3,4‐oxadiazoles 13 and 14 have been obtained.The behaviour of bromosemicarbazones [10a,b] and of the bromo‐tetrahydrotriazine 9 towards heating or treatment with base has also been investigated.
Réactions de substitution nucléophile de l'hydroxyurée. Synthèse et étude des oxa‐6 dihydrouraciles
Authors: Bennouna Chakib , Petrus Francpise , Verducci Jean 
Published: April 2009

AbstractL'action de l'hydroxyurée, hydroxylamine N‐protégée, sur les α‐bromoesters conduit aux α‐ureidoxyésters isolables dans certains cas; leur cyclisation est une voie de synthèse des oxa‐6 dihydrouraciles dont la structure est prouvée par les méthodes physicochimiques: en particulier la rmn 13C met en évidence la présence de la seule forme tautomère dicarbonylée.
Synthesis of 2‐amino‐3‐methoxypyrazinc
Authors: Bolta M. , De Angelis F. , Nicoletti R. 
Published: April 2009

AbstractA new synthesis of 2‐amiuo‐3‐methoxypyrazine, an intermediate in the synthesis of sulfalene, via 2‐carbamido‐3‐hydroxy pyrazine and subsequent Hofmann rearrangement of 2‐carhamido‐3‐methoxypyrazine, is described.
Polycondensed nitrogen heterocycles. VII. 5,6‐Dihydro‐7‐h‐pyrrolo[1,2‐D]‐[1,4] benzodiazepin‐6‐ones. A novel series of annelatcd 1,4‐benzodiazepines
Authors: Aiello Enrico , Dattolo Gaetano , Cirrincione Girolarno , Plescia Salvalor E. , Daidone Giuseppe 
Published: April 2009

AbstractThe synthesis of a novel class of annelated 1,4‐benzodiazepinen, the 2‐R‐3 methyl‐5,6‐dihydro‐7H‐pyrrolo[1,2‐d][1,4]benzodiazepin‐6‐ones (Ve‐e), is described. The reaction of 2‐(o‐aminophenyl)‐3‐R‐5‐methylpyrroles(IIIa,b) with bromoacetyl bromide in the presence of triethylamine produced the title compounds. An alternative synthetic route was achieved by means of the reactions of 1a,b with the appropriated α‐aminoacids. The catalytic reduction of IVe‐e over 10% palladium on charcoal led in good to excellent yields directly to the formation of pyrrolo[1,2‐d]‐[1,4]benzodiazepines (Ve‐e).
Synthesis of 1,2,4‐oxadiazines and their rearrangement to pyrimidines
Authors: Santilli Arthur A. , Scotese Anthony C. 
Published: April 2009

AbstractSeveral amide oximes underwent condensation reactions with dimethyl acetylene dicarboxylate to afford 1:1 adducts. Under basic conditions, these adducts underwent ring closure to afford several methyl [3‐(substituted)‐4,5‐dihydro‐5‐oxo‐6H‐1,2,4‐oxadiazin‐6‐ylidene]acetates. The reactions of these compounds with a variety of amines resulted in addition‐rearrangement reactions with the formation of the corresponding methyl 2‐substituted‐5‐substituted amino‐1,6‐dihydro‐6‐oxo‐4‐pyrimidine carboxylates.
Reaction of sulfene with n,N‐disubstituted α‐aminomethyleneketones vi. Synthesis of n,n‐disubstituted 4‐amino‐3,4‐dihydro‐6‐phenyl‐1,2‐oxathiin 2,2‐dioxides and of 4‐methylphenylamino‐3,4‐dihydro‐5,6‐polymethylen‐1,2‐oxathiin 2,2‐dioxides
Authors: Evangelisti Filippo , Schenone Pietro , Bargagna Alberto 
Published: April 2009

AbstractThe title compounds were obtained by cycloaddition of sulfene to N,N‐disubstituted 3‐amino‐1‐phenyl‐2‐propen‐1‐ones and to 2‐metbylphenylaminomethylenecycloalkanones, respectively. Steric and electronic aspects of these reactions, as well as the failure of cycloaddition in the case of N,N‐disubstituted 4‐arnino‐3‐buten‐2‐ones, are also discussed.
Ethers of indoxylie acid
Authors: Calun Arjeh , Us Arie Mark , Kampf Arieh 
Published: April 2009

AbstractO‐alkylations of indoxylie acid (2b) to produce 3‐indolyl‐alkyl ethers and a synthesis of 5‐melhoxy‐2‐earboxyindol‐3‐oxyaeetic acid (25) are described.
Synthesis and aikylation of CIS‐α‐hydroxyisopropylindanone‐2‐carboxylic acid lactone
Authors: Campaigne E. , Frierson Manton R. 
Published: April 2009

AbstractThe Meldrum's acid adduct of isobutyrophenone was cyclized directly and in high yield to the title compound, which could then be alkylated at the 2‐position with methyl iodide or ethyl 6‐bromohexanoate. In the latter case, acid hydrolysis of the resultant ester gave the analogous acid, but alkaline hydrolysis resulted in ring opening of the indanone portion of the molecule.
Synthesis of 2‐methylcarbamazepine, a new internal standard for chromatographic assays of carbamazepine (tegretol®)
Authors: Patton Jeffrey R. , Dudley Kenneth H. 
Published: April 2009

AbstractThe synthesis of 2‐methyl‐5H‐dibenz[b,f]azepine‐5‐carboxamide (2‐methylcarbamazepine, 2‐MCBZ, 8), a promising internal standard for chromatographic assays of the antiepileptic agent carbamazepine (CBZ, 1), is described. N‐(p‐Tolyl)anthranilic acid (2) was utilized as a starting material for the synthesis of a key compound, 2,9‐dimethylacridine (4), which was converted in two steps to 2‐methyl‐9‐hydroxymethylacridan (6). The acridan 6, in the presence of poly‐phosphoric acid, was ring‐expanded to form 2‐methyl‐5H‐dibenz[b,f]azepine (7), this latter compound being converted by conventional reactions to its 5‐carbamyl derivative, 2‐MCBZ (8).
v‐triazolines. XI . Rearrangement of 1‐aryl‐4,5‐diamino‐4,5‐dihydro‐v‐triazoles
Authors: Citerio L. , Saccarello M. L. , Trimarco P. 
Published: April 2009

AbstractThe reaction of arylazides with 1,2‐diaminoethylenes (1a‐b) or α,β‐diaminostyrenes (1c‐f) gave N‐(1,2‐diaminoethylideneanilines (2a‐e) and N‐(1,2‐diamino‐2‐phenylethylidene)anilines (2g‐i), respectively. These amidine derivatives are formed through the rearrangement of unstable 1‐aryl‐4,5‐diamino‐v‐triazolines. The regiospecificity of the cycloaddition reaction has been elucidated on the basis of the products obtained.
Nuclear magnetic resonance data of pyrido[2,3‐B] pyrazines and their σ‐adducts with amide ion and water
Authors: Nagel A. , Van Der Plas H. C. , Geurtsen G. , Van Veldhuizen A. 
Published: April 2009

Abstract13C nmr spectral data of the parent substance pyrido[2,3‐b]pyrazine and several of its derivatives (containing one or more chloro, amino, oxo, bromo, fluoro, phenyl, methyl, hydrazino or t‐butyl substituents) are reported. The 13C nmr spectrum of the parent substance has been assigned conclusively by 13C‐labelling. Additionally we proved, the existence of anionic 1:1 σ‐adducls i.e., 3‐amino‐3,4‐dihydropyrido[2,3‐b]pyrazine, the formation of 3‐amino‐2‐t‐butyl‐6‐chloro‐3,4‐dihydropyrido[2,3‐b]pyrazinide ion and by 1H nmr spectroscopy 2‐amino‐1,2‐dihydro‐3‐phenylpyrido[2,3‐b]pyrazinide ion. The 13C nmr data of the cation of the dihydrale 2,3‐dihydroxy‐1,2,3,4‐tetrahydropyrido[2,3‐b]pyrazine, present in a solution of the parent compound in N hydrochloric acid, are given.
Carboxylic n,N‐diphenylcarbamic anhydrides. New acylating agents
Authors: Shepard Kenneth L. , Halczenko Wasyl 
Published: April 2009

AbstractCarboxylic N,N‐diphenylcarbamic anhydrides have been isolated from the reaction of carboxylate salts with 1‐(N,N‐dipheriylcarbamoyl)pyridinium chloride in aqueous or ethanolic solution. These anhydrides have been shown to be stable, crystalline derivatives and to be very reactive in acylation reactions.A comparison of pyrazinecarboxylic acid derivatives demonstrated these products to be more reactive than cyanomethyl esters or the so‐called Woodward's esters, acyloxyacrylamides.
Sels d'aziridinium stables c‐fonctionnalisés II: Stéréochimie de la quaternisation, synthèses stérèodirigées de composés n‐trideutériométhylés et attribution de leurs configurations relatives par el'fet overhauser nucléaire
Authors: Rivoirard Eve‐Marie , Raret Paul , Boucherle André , Gey Claude , Pierre Jean‐Louis 
Published: April 2009

AbstractDiverses aziridines C‐fonetionnalisées N‐méthylées et N‐éthylées ou N‐trideutériométhylées, de configuration a l'azote déterminée, sont quaternisées a différentes temperatures respectivement par le fluorosulfate de méthyle et le fluorosulfate de méthyle‐d3. Les configurations des ions aziridiniums épimères formés sont établies par effet Overhauser nucléaire. La stéréochimie de la reaction est discutée.
The preparation and stereochemistry of 1‐chloroethyl‐4‐methyl‐6,7‐dimethoxyisochroman
Authors: Mccall John M. , Tenbrink Ruth E. , Kamdar Bharat V. , Chidester Constance 
Published: April 2009

AbstractThe boron trifluoride catalyzed reaction of 2‐methyl‐2‐(3,4‐dimethoxypbenyl)ethanol and chloropropionaldehyde diethyl acetal yields a mixture of cis and trans 1‐ehloroethyl‐4‐methyl‐6,7‐dimethoxyisochroman. The structure of the trans compound was established by X‐ray analysis. The trans compound equilibrates to a mixture of the cis and trans when exposed to boron trifluoride catalyst.
Reaction of hydrazine with aryl and heterocyclic selenoamides and alkylselenone esters. Synthesis of 2,5‐diaryl and diheteroeyclic‐1,3,4‐selenodiazoles and dialkylselenone ester‐hydrazones
Authors: Cohen Victor Israel 
Published: April 2009

AbstractHydrazine reacted with alkylselenone esters to give dialkylselenone ester‐hydrazones. Reaction of selenoamides with the same reagent led to 2,5‐disubslituled‐1,3,4‐selenodiazoles.
General synthesis of 1a,7b‐dihydro‐1H‐cyclopropa[c]cinnolines with electron‐withdrawing substituents in the 1a‐position
Authors: Garanti Luisa , Zecchi Gaetano 
Published: April 2009

Abstract2‐Vinylphenylhydrazonyl chlorides (4) react with triethylamine in boiling benzene to afford the title compounds (6) in 54–72% yield, probably through nitrile imine intermediates (5).
Sulphur heterocycles from thiodiacetonitrile and sulphonyldiacetonitrilc
Authors: Crombie D. A. , Kiely J. R. , Ryan C. J. 
Published: April 2009

AbstractThiodiacetonitrile reacted with α‐diketones to form 5‐cyano‐2‐thiophenecarboxamides and with α‐keto esters to give 3‐hydroxy‐2,5‐thiophenedicarbonitriles. Sulphonyldiacclonitrile condensed with α,β‐unsaturated ketones to give 6‐cyano‐3,4‐dihydro‐1,1‐dioxo‐2H‐thiopyran‐2‐carboxamides.
Synthesis and reaction of 2,7‐dimethylpyrrolo[1,2‐A]quinoline with electrophilic reagents
Authors: Kuo Hsien‐Saw , Yoshina Shigetaka , Tung Yih‐Chih 
Published: April 2009

Abstract2,7‐Dimethylpyrrolo[1,2‐a]quinoline (1) was synthesized from 2,6‐dimethylquinoline and bromoaeetone via a Tsebitsehibabin reaction. The electrophilic substitution reactions of I, namely, nitrosation, acylation, diazonium coupling, formylation, bromination, and nitration were studied.
One‐step synthesis of N‐[(methylthio)methyl]imidazole and related heterocyclic derivatives via a fummerer rearrangement
Authors: Janzen A. F. , Lypka G. N. , Wasylishen R. E. 
Published: April 2009

AbstractN‐[(Methylthio)methyl]imidazole may be prepared from dimethylsulfoxide and N‐(trimethylsilyl)imidazole or N‐(t‐butyldimethylsilyl)imidazole at elevated temperatures via a Purnmerer rearrangement. The product was characterized by elemental analysis, mass spectrometry and proton and carbon nmr. Preliminary experiments show that corresponding derivatives of 2‐methylimidazole, pyrazole, triazole and benzimidazole may also be prepared in an analogous manner.
3(2H)Furanone derivatives. Ring‐chain tautomerism in the 1,3,4,6‐tetraketone series
Authors: Poje M. , Balenovic K. 
Published: April 2009

AbstractRing‐chain tautomeric equilibria in the 1,3,4,6‐tetraketone series 1 have been examined and the identification of the chain‐form 2 and hydroxyfuranone 3 has been accomplished from 1H‐nmr spectra; the relative contribution of the two depends on the structure and also on the solvent. Conversions of 1 into 3(2H)furanones 4 and 5 involving the cyclic tautomer 3 are described.
Synthesis of substituted 2‐methyl‐3‐(3,4‐dimethoxy/dihydroxyphenylethyl)4‐quinazolones as possible antiparkinson drugs
Authors: Parmar Surendra S. , Singh Shiva P. 
Published: April 2009

AbstractSeveral substituted 2‐methyl‐3‐(3,4‐dimethoxy/dihydroxyphenylethyl)‐4‐quinazolones were synthesized as possible antiparkinsonism agents. The structure of these compounds were confirmed by their elemental and spectral analysis.
Nitrogen bridgehead compounds. IX. Synthesis and reactions of 2,3‐disubstituted pyrido[1,2‐a]pyrimidin‐4‐ones
Authors: Fülöp F. , Hermecz I. , Mészáros Z. , Dombi Gy. , Bernáth G. 
Published: April 2009

AbstractA series of 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones was prepared by the cyclization of substituted 2‐aminopyridines with βketocarboxylic esters in polyphosphoric acid or in mixtures of the latter with phosphoryl chloride. Catalytic hydrogenation (over palladium on charcoal or Raney nickel) of the products afforded the corresponding 6,7,8,9‐tetrahydropyridopyrimidinones. Thermal treatment of the 6‐substituted derivatives gave 1,8‐naphthyridin‐4‐ones in high yields. Oxo to thio exchange was successful only with substrates unsubstituted at C‐6.
Reaction of nitrenes with strained olefins. Preparation and reactions of some 6‐azabicyclo[3.1.0]hexanes
Authors: Meyer G. Richard , Kellert Cheryl A. , Ebert Robert W. 
Published: April 2009

AbstractA number of examples of the 6‐azabicycIo[3.1.0]hexane ring system have been prepared by the oxidation of N‐aminophthalimide or 3‐amino‐2‐methyl‐4‐quinazoIone with lead tetraacetate in the presence of variously substituted cyclopentenes.Thus, 6‐phthalimidyl‐6‐azabicyclo[3.1.0]hexane, dimethy 1–6‐phthalimidyl‐6‐azabicyclo[3.1.0]‐hexane‐1,5‐dicarboxylate, 2,3‐benzo‐6‐phthalimidyl‐6‐azabicycIo[3.1.0]hexane and N‐3‐(2‐methyl‐4‐quinazolyl)‐6‐azabicyclo [3.1.0]hexane were prepared for the first time. All of the new compounds were found to be stable in refluxing carbon tetrachloride and chlorobenzene. Refluxing 6‐phthalimidyl‐6‐azabieyclo[3,1.0]hexane in acetic acid for 24 hours resulted in quantitative rearrangement to a phthalohydrazide, 8.
Reactivity studies of S‐methylthiophenium tetrafluoroborates
Authors: Horak Vaclav , Ee Khoo Lian , Párkányi Cyril 
Published: April 2009

AbstractThe polarographic behavior of four S‐methylthiophenium tetrafluoroborates, I‐IV, has been investigated in Britton‐Robinson aqueous buffers. The compounds under study were the S‐methylbenzo[b]thiophenium (I), S‐methylnaphtho[2,3‐b]thiophenium (II), S‐methyldibenzothiophenium (III), and S‐methylnaphtho[2,1‐b]thiophenium (IV) tetrafluoroborates which were obtained from the parent sulfur heterocycles by their reaction with methyl iodide and silver tetrafluoroborate in 1,2‐dichloroethane, II and IV being new compounds. Compounds I‐IV give two one‐electron reduction waves and the more positive wave appears to be associated with an electron transfer from the electrode to the LUMO of the substrate as indicated by the experimental E1/2 vs calculated LUMO values plot (Figure 2). The rates of demethylation of the ions I‐IV with the iodide ion acting as the nucleophile have been determined in the Britton‐Robinson buffer (pH 6)‐acetonitrile solution at 24°. The results of the polarographic study and of the kinetic studies with the iodide ion confirm the high reactivity of S‐methylthiophenium ions which originates in the antiaromatic destabilization of these structures.