bluuebunny/crossref_metadata_2025_split huggingface dataset:
New heterocycles derived from a simultaneous substitution and reductive acetylation of 2,5‐dihydroxy‐1,4‐benzoquinone by N‐containing heterocycles
Authors: Farfán N. , Ortega E. , Contreras R. 
Published: March 2009

AbstractReaction of 2,5‐dihydroxy‐1,4‐benzoquinone with pyridine, 3‐picoline and acridine in acetic anhydride lead to the preparation of 3‐(4‐pyridyl)‐1,2,4,5‐benzenetetrol tetraacetate, 3‐[4‐(3‐methylpyridyl)]‐1,2,4,5‐benzenetetrol tetraacetate and 3‐(9‐acridyl)‐1,2,4,5‐benzenetetrol tetraacetate, respectively. Moreover, it was possible to isolate the complex derived from the corresponding amines and the quinone. The reaction conditions and the 1H, 13C, ir and mass spectra of the new compounds are discussed.
Synthesis of 4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine
Authors: Moron Jacqueline , Bisagni Emile 
Published: March 2009

Abstract4‐Methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine (3) was synthetized from 2‐acetylfuro[3,2‐f]benzo[b]furan (4) or from 2‐acetyl‐5,6‐dihydrofuro[3,2‐f]benzo[b]furan (10). The key step involves a rearrangement‐cyclization of azides 6 and 12 to form 4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridin‐1(2H) one (7) and 8,9‐dihydro‐4‐methylfuro[3′,2′:5,6]benzofuro[3,2c]pyridin‐1(2H)‐one (13). Introduction of an aminoalkyl chain on carbon 1 was effected by substitution of 1‐chloro‐4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine (8).
Proton‐Ionizable crown compounds. 7. Synthesis of new crown compounds containing the dialkylhydrogenphosphate moiety
Authors: Bradshaw Jerald S. , Huszthy Peter , Izatt Reed M. 
Published: March 2009

AbstractA new series of macrocyclic ligands containing the dialkylhydrogenphosphate moiety is reported. These compounds were prepared by reacting phosphorus oxychloride with the appropriate oligoethylene glycol followed by a hydrolysis step. One of these new macrocyclic compounds transported the alkali metal cations as well as lead, zinc and silver ions.
Synthesis of heterocyclic propellanes via 1,3‐dipolar cycloaddition reactions to bicyclo[5.3.0]dec‐1(7)‐en‐2‐onea
Authors: Coutouli‐Argyropoulou E. , Malamidou‐Xenikaki E. 
Published: March 2009

AbstractThe synthesis of several heterocyclic propellanes via 1,3‐dipolar cycloaddition reactions of arylnitrile oxides, diarylnitrilimines and arylazides with bicyclo[5.3.0]dec‐1(7)‐en‐2‐one is described and the spectral properties of the obtained propellanes are discussed. The cycloadditions are also examined on the basis of frontier molecular orbitals (FMO) of the reacting species.
Synthesis of 11‐aza‐5H‐benzophenoxazin‐5‐one and 11‐Aza‐5H‐pyridophenoxazin‐5‐one derivatives
Authors: Nan'ya Seiko , Maekawa Eturô , Kang Wen‐Bing , Ueno Yoshio 
Published: March 2009

AbstractThe 1,6‐disubstituted‐ and 4,6‐disubstituted‐11‐aza‐5H‐benzo[a]phenoxazin‐5‐one as well as 6‐substituted‐11‐aza‐5H‐pyrido[a]phenoxazin‐5‐one derivatives were prepared by the condensation of 2‐amino‐3‐hydroxypyridine with 5‐substituted‐2,3‐dihalogeno‐1,4‐naphthoquinones and 6,7‐dibromo‐5,8‐quinolinequinone respectively. The resulting compounds were subjected to reduction, acetylation, dehalogenation and reaction with aniline.
A novel synthesis of benzofuran and related compounds. III. The vilsmeier reaction of phenoxyacetaldehyde diethyl acetals
Authors: Hirota Takashi , Fujita Hiroko , Sasaki Kenji , Namba Tetsuto 
Published: March 2009

AbstractA novel synthesis of 2‐benzofurancarbaldehydes by the Vilsmeier reaction of phenoxyacetaldehyde diethyl acetals is described.
Réactivité des cinnamoyl‐3 pyrones‐2 vis à vis des amines primaires
Authors: Chergui Djamel , Hamdi Maâmar , Baboulène Michel , Spéziale Vincent , Lattes Armand 
Published: March 2009

AbstractL'action d'amines primaires (méthylamine, isopropylamine, benzylamine) en milieu neutre, sur des cinnamoyl‐3 pyrones‐2 s'effectue avec ouverture du cycle suivie d'une décarboxylation. La structure des amino‐7 dioxo‐3,5 octadiènes‐1,6 (2) ainsi obtenus a été déterminée par différentes méthodes: analyse élémentaire, spectrométrie de masse, rmn1H et 13C.
Synthesis of 1‐ and 4‐substituted‐5H‐benzo[a]phenoxazin‐5‐ones
Authors: Hayakawa Hitoshi , Nan'ya Seiko , Yamamoto Tetsuo , Maekawa Eturô , Ueno Yoshio 
Published: March 2009

AbstractThe 1‐ and 4‐substituted‐5H‐benzo[a]phenoxazin‐5‐ones (substitutents: nitro, amino and acetylamino) were prepared by the condensation of o‐aminophenol with 5‐substituted‐2,3‐dichloro‐1,4‐naphthoquinones. The resulting compounds were subjected to reduction, acetylation and dehalogenation.
1H‐NMR, Ultraviolet and infrared spectra of some (Z)‐α‐(phenyl)‐β‐(2‐furyl), ‐(2‐pyrrolyl) and ‐(N‐methyl‐2‐pyrrolyl)acrylonitriles
Authors: Alberghina Gaetano , Amato Maria Emanuela , Bottino Francesco Agatino , Corsaro Antonino , Fisichella Salvatore 
Published: March 2009

AbstractThe 1H‐nmr data of some (Z)‐α‐(p‐substituted‐phenyl)‐β‐(2‐furyl), ‐(2‐pyrrolyl), and ‐(N‐methyl‐2‐pyrrolyl)‐acrylonitriles have been investigated to indicate the preferred conformation and to establish the conformational preferences of the β‐heterocyclic ring. The ultraviolet spectra have been discussed in order to obtain information about the chromophores responsible for the absorption. The infrared spectra have been analyzed for the identification of the main absorption frequencies of cyano and ethylenic groups and to assign the characteristic absorption bands to specific normal vibrations of the heteroaromatic nuclei.
Studies on pyrrolidinones. Michael reaction of glutamic acid and diethylglutamate
Authors: Rigo Benoît , Couturier Daniel , Kolocouris Nicolas 
Published: March 2009

AbstractStarting from glutamic acid or diethyl glutamate, some derivatives of N‐(2‐carboxyethyl), N‐(3‐oxobutyl) and N‐(2‐cyanoethyl)pyroglutamic acid were synthesized.
Heterocyclic compound studies. II. Synthesis of 1,4‐benzodioxin, 1,4‐benzoxathiin, 1,4‐benzoxazine and 1,4‐benzothiazine derivatives
Authors: Cabiddu Salvatore , Floris Costantino , Melis Stefana , Sotgiu Francesca , Cerioni Giovanni 
Published: March 2009

AbstractBenzocondensed six‐membered heterocyclic rings containing two heteroatoms have been synthesized by a generally applicable method starting from disubstituted benzene compounds and methyl 4‐chlorobutynoate (1) or methyl 4‐bromobutenoate (2). The reactions with 1 yield a mixture of endo and exo (E or Z) isomers. The 13C nmr spectroscopy was used to assign the structure of the synthesized compounds.
Proton‐Ionizable crown compounds. 8. Synthesis and structural studies of macrocyclic polyether ligands containing a 4‐thiopyridone subcyclic unit
Authors: Bradshaw Jerald S. , Huszthy Peter , Koyama Hiroyuki , Wood Steven G. , Strobel Scott A. , Davidson Richard B. , Izatt Reed M. , Dalley N. Kent , Lamb John D. , Christensen James J. 
Published: March 2009

AbstractThree new proton‐ionizable macrocyclic polyether ligands containing the 4‐pyridone subcyclic group have been prepared. Two of these ligands contain lipophilic n‐octyl substituents, the other ligand contains a phenyl substituent. The 15‐crown‐5 ligand containing both a 4‐pyridone subcyclic unit and an n‐octyl substituent selectively transported lithium cations in a water‐methylene chloride‐water bulk liquid membrane system. Five crown compounds containing the 4‐pyridone subcyclic unit were converted to the 4‐thiopyridono‐crown compounds when treated with Lawesson's Reagent. The crystal structure of 4‐thiopyridono‐18‐crown‐6 shows a carbon‐sulfur double bond and a molecule of water hydrogen bonded inside the macrocycle cavity.
Synthesis of certain 3‐alkoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidines structurally related to adenosine, inosine and guanosine
Authors: Anderson Jack D. , Dalley N. Kent , Revankar Ganapathi R. , Robins Roland K. 
Published: March 2009

AbstractSeveral 3‐alkoxysubstituted pyrazolo[3,4‐d]pyrimidine ribonucleosides structurally related to adenosine, inosine and guanosine have been prepared by the direct glycosylation of preformed aglycon precursor containing a 3‐alkoxy substituent. Ring closure of 5(3)‐amino‐3(5)‐ethoxypyrazole‐4‐carboxamide (6b) with either formamide or potassium ethyl xanthate gave 3‐ethoxyallopurinol (7b) and 3‐ethoxy‐6‐thioxopyrazolo[3,4‐d]‐pyrimidin‐4(5H,7H)‐one (10), respectively. Methylation of 10 gave the corresponding 6‐methylthio derivative 15. Similar ring annulation of 5(3)‐methoxypyrazole‐4‐carboxamide (6a) with formamide afforded 3‐methoxyallopurinol (7a). Treatment of 5(3)‐amino‐3(5)‐methoxypyrazole‐4‐carbonitrile (5a) with formamidine acetate furnished 4‐amino‐3‐methoxypyrazolo[3,4‐d]pyrimidine (4). High‐temperature glycosylation of 7b with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐D‐ribofuranose in the presence of boron trifluoride etherate gave a 2:1 mixture of N‐1 and N‐2 glycosyl blocked nucleosides 11b and 13b. Deprotection of 11b and 13b with sodium methoxide gave 3‐ethoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (12b) and the corresponding N‐2 glycosyl isomer 14b, respectively. Similar glycosylation of either 4 or 7a, and subsequent debenzoylation gave exclusively 4‐amino‐3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidine (9) and 3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4‐(5H)‐one (12a), respectively. The structural assignment of 12a was made on the basis of single‐crystal X‐ray analysis. Application of this general glycosylation procedure to 15 gave the corresponding N‐1 glycosyl derivative 16 as the sole product, which on debenzoylation afforded 3‐ethoxy‐6‐(methylthio)‐1‐(3‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (17). Oxidation of 16 and subsequent ammonolysis furnished the guanosine analog 6‐arnino‐3‐ethoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]‐pyrimidin‐4(5H)‐one (19). Similarly, starting from 3‐methoxy‐4,6‐bis(methylthio)pyrazolo[3,4‐d]pyrimidine (20), 6‐amino‐3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (23) was prepared.
Desulfation and rearrangement of tigemonam to an isoxazolidin‐5‐one and the synthesis of the rearrangement product
Authors: Singh Janak , Kissick Thomas P. , Fox Rita , Kocy Octavian , Mueller Richard H. 
Published: March 2009

AbstractThe β‐lactam antibiotic Tigemonam 2 undergoes desulfation to the N‐hydroxyazetidinone 4, which rearranges to the isoxazolidin‐5‐one 6. The structure of the rearrangement product 6 was confirmed by synthesis.
Reactions of 2‐, 3‐, and 4‐(N‐nitroso)methylaminopyridine with esters containing active methylene groups
Authors: Kiriazis L. , Kalatzis E. , Alexandrou N. E. 
Published: March 2009

Abstract2‐N‐Nitrosomethylaminopyridine but not 2‐methylaminopyridine, 3‐N‐nitrosomethylamino‐ or 3‐methyl‐aminopyridine and 4‐N‐nitrosomethylamino‐ or 4‐methylaminopyridine react with malonate esters to form the corresponding derivatives of carbamates, amides and dihydropyridines respectively. In the reaction of the 4‐isomers with diisopropyl malonate small amounts of the corresponding carbamates was also formed.
Synthèse de dioxinocoumarines angulaires
Authors: Guillaumet Gérald , Hretani Mohamed , Coudert Gérard 
Published: March 2009

AbstractLes synthèses des dioxinocoumarines angulaires 1 et 2 apparentées aux angélicines sont décrites. Elles sont réalisées respectivement en huit et dix étapes à partir de l'amino‐6 benzodioxanne‐1,4 et du méthoxy‐3 catéchol.
Novel crown ethers with pendant, proton‐ionizable, chromogenic groups
Authors: Czech Bronislaw P. , Babb David A. , Czech Anna , Bartsch Richard A. 
Published: March 2009

AbstractSynthesis of fifteen new chromogenic crown ethers is described in which one phenyl group of diphenylamine has been substituted at the 2‐, 4‐, and 6‐positions with strongly electron‐withdrawing groups and the other phenyl group bears an oxymethyl crown ether substituent. Structural variations include the crown ether ring size, identity of the electron‐withdrawing groups, acidity of the amine function, and positioning of the oxymethyl crown ether substituent ortho, meta, and para to the amine nitrogen. Preparation of a structurally‐related chromogenic bis(crown ether) is also reported.
Heterocycles. Part XVII. Synthesis of new substituted 2,3,3a,4,5,6‐hexahydrobenzo[6,7]cyclohepta[1,2‐c]pyrazoles and related compounds
Authors: El‐Rayyes N. R. , Bahtiti N. H. 
Published: March 2009

AbstractAryl aldehydes I reacted with 1‐benzosuberone to yield the corresponding 2‐arylidene‐1‐benzosuberones II. Condensation of II with hydrazine and its derivatives provided the substituted 2,3,3a,4,5,6‐hexahydro‐benzo[6,7]cyclohepta[1,2‐c]pyrazoles III‐VI respectively. The structures of all products were assigned by chemical and spectroscopic methods.
Reaction of 2,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole with primary amines. Synthesis of 4‐substituted‐3,5‐bis(trifluoromethyl)‐4H‐1,2,4‐triazoles
Authors: Reitz David B. , Finkes Michael J. 
Published: March 2009

AbstractReaction of 3,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole (1a) with primary amines under a variety of conditions conveniently produced 4‐substituted‐3,5‐bis(trifluoromethyl)‐4H‐1.2,4‐triazoles 4a in 26‐85% yield. Alkyl amines reacted with 1a in methanol at −42° to provide hydrogen‐bonded monoadduct‐methanol complexes 5a, as determined by X‐ray. The reaction of 1a with sterically hindered or strongly electron deficient anilines required high temperatures in the absence of solvent.
The synthesis and properties of 2‐substituted dihydropyrimidines
Authors: Kashima Choji , Shimizu Masao , Omote Yoshimori 
Published: March 2009

AbstractVarious 2‐substituted 1,4‐dihydro‐4,4,6‐trimethyl‐1‐phenylpyrimidines and 1,6‐dihydro‐4,6,6‐trimethylpyrimidines were synthesized independently. For these dihydropyrimidines, the physical data such as the uv, ir, and nmr spectra and the oxidation potential were compared. 2‐Dimethylamino substituted dihydropyrimidine showed the lowest oxidation potential, which expected the similar reducing ability as dihydropyridines.
Constantes d'acidité de quelques bihétérocycles
Authors: Tjiou El Mostafa , Fruchier Alain , Pllegrin Valdo , Tarrago Georges 
Published: March 2009

AbstractLes pKa1 et pKa2 de 19 bihétérocycles de formule générate A‐(CH2)n‐B (où A et B représentent un pyrazole, un imidazole ou une pyridine, et n = 0 ou 1) sont déterminés dans l'eau à 25° par potentiométrie et par spectrométrie uv.
Synthesis and 1H‐, 13C‐NMR analysis of some substituted 1,2,3,4‐tetrahydroisoquinolines
Authors: Ibañez A. F. , Yaculiano G. B. , Iglesias G. Y. Moltrasio 
Published: March 2009

AbstractSynthesis and 1H‐, 13C‐nmr analysis of some substituted 3‐phenyl‐1,2,3,4‐tetrahydroisoquinolines are reported. Spectroscopy assignments of hydrogen and carbon resonances were made on the basis of standard chemical shift theory, comparison with reference compounds, attached proton test and fully coupled 13C‐nmr spectra. Data showed that at room temperature two conformers predominated for the 1,3‐disubstituted and 1,2,3‐trisubstituted isoquinolines.
Synthesis of N‐heterocycles via chalcone epoxides. 1. Amino and hydrazinopyrimidines
Authors: Osisanya Rasaki Abayomi , Oluwadiya James Olabisi 
Published: March 2009

AbstractChalcone epoxides have been used as precursors in the synthesis of 2‐amino‐ and 2‐hydrazinopyrimidines.
On triazoles XVIII. . an unexpected rearrangement observed during the reaction of 5‐amino‐1,2,4‐triazoles with N‐heterocyclic β‐oxo‐esters
Authors: Reiter JóZsef , Rivó Endre 
Published: March 2009

AbstractIn the course of the synthesis of pyrido[4,3‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives 3c representing a novel ring system an unexpected rearrangement of the intermediate enamines to yield 5 was observed. A mechanism of the formation of 5 was suggested. The isomeric pyrido[4,3‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives 4c containing also a new ring system were obtained, too. The structure of products obtained was proved with the help of their uv, cmr and X‐ray spectra.
Synthèse de C‐nucléosides dérivés de l'hydroxy‐8 (1,2,4)triazolo[1,5‐c] et [4,3‐c]pyrimidines
Authors: Dennin F. , Rousseaux O. , Blondeau D. , Sliwa Et H. 
Published: March 2009

AbstractLes ethers et esters correspondant aux nouveaux C‐nucléosides β‐D‐ribofuranosyl‐2‐hydroxy‐8(1,2,4)triazolo[1,5‐c]pyrimidine et (hydroxy‐2 ethoxymethyl)‐2 hydroxy‐8 (1,2,4)triazolo[1,5‐c]pyrimidine ont été obtenus par condensation de la benzyloxy‐5 hydrazino‐4 pyrimidine avec le chlorhydrate de benzoyloxy‐5 β‐D‐ribofuranosyl formimidate de thiobenzyle pour les premières et avec les chlorhydrates de (benzoyloxy‐2 éthoxy)‐2 acétimidate d'éthyle ou de thiobenzyle pour les seconds. L'action du méthanol ammoniacal suivie d'hydrogénolyse permet d'accéder à ces nouveaux C‐nucléosides, dérivés de phénols hétérocycliques dont les structures ont été établies par uv, ir et rmn.
Pyridazines. XLV . on the mechanism of an unusual 1,2‐diazine → 1,2‐diazole ring contraction
Authors: Heinisch Gottfried , Huber Thierry , Langer Christina , Gössler Walter , Kollenz Gert 
Published: March 2009

AbstractStarting with succinic acid‐2,3‐13C, phenyl(4‐pyridazinyl)methanol‐4,5‐13C was prepared in order to gain insight into the mechanism of an unusual pyridazine into pyrazole rearrangement reported previously. According to the 13C‐nmr spectrum of labeled 1‐phenyl‐2(4‐pyrazolyl)ethanone obtained upon p‐toluenesulfonic acid mediated ring contraction, the methylene and the pyrazole C‐4 carbon atoms of the reaction product originate from the pyridazine carbon atoms 4 and 5 of the educt. Thus, a mechanism for this ring‐transformation is proposed involving well stabilized carbocations as intermediates.
Nitrogen bridgehead compounds. Part 76 Synthesis and stereochemistry of ethyl 9‐benzylidene‐6,7,8,9‐tetrahydro‐2‐oxo‐2H‐ and 4‐oxo‐4H‐pyrido[1,2‐a]pyrimidine‐3‐carboxylates and their homologues
Authors: Sipos Judit , Podányi Benjamin , Hermecz István , Pusztay Levente , Tóth Gábor , Szilágyi László 
Published: March 2009

AbstractEthyl 4‐oxo‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyrimidine‐3‐carboxylates 1–4, their piperidine ring homologues 5–6 and their 2‐oxo isomers 7–9 were reacted with benzaldehyde. At low temperature, kinetically stable addition products were formed. Thermodynamically stable condensation products were obtained at higher temperature, which were also formed when the addition products were refluxed in benzene. The 9‐benzyl derivatives were prepared by the hydrogenation of the condensation products over Pd/C. The stereochemical features of the new compounds were determined via 1H and 13C nmr chemical shift and coupling constant analysis and NOE measurements.
Reaction of 6‐aminopyrimidin‐4‐ones with diethyl ethoxymethylenemalonate in several media: Synthesis of pyrido[2,3‐d]pyrimidines
Authors: García José A. , Sánchez Adolfo , Nogueras Manuel 
Published: March 2009

AbstractReactions of 6‐amino‐3,4‐dihydro‐2‐methoxy‐4‐oxopyrimidine 1 and its 3‐methyl derivative 2, with diethyl ethoxymethylenemalonate (EMME) are discussed in this paper. These reactions have been carried out in the following media: under fusion, ethanol, sodium methoxide/methanol, sodium ethoxide:ethanol and acetic acid media. In acetic medium, mixtures of products proceeding from C‐alkylation and N‐alkylation were obtained, while in the remaining conditions only products of N‐alkylation were obtained.
Synthèse de pyrimidines et purines adamantylées par alkylation régiosélective directe, en catalyse par transfert de phase
Authors: Hedayatullah Mir , Roger Annie 
Published: March 2009

AbstractLa monoalkylation régiosélective de l'uracile, de la thymine, de l'adénine, de l'aza‐8 adénine et de la théophylline est réalisee par l'emploi d'un alkylant dérivé de l'adamantane, en catalyse par transfert de phase. Dans les měmes conditions, le barbital et le phénobarbital ont fourni les dérivés N1,H3‐dialkyles correspondants. L'influence de la nature de l'agent alkylant sur la sélectivité observée est discutée.
1H and 13C NMR and x‐ray diffraction studies on pyrazolo[1,5‐b][1,2,4]triazine — A new heterocyclic system
Authors: Sliskovic D. Robert , Ashcroft Joseph , Morton George O. , James John C. , Lin Yang‐I. 
Published: March 2009

AbstractThe 1H and 13C nmr resonances of pyrazolo[1,5‐b][1,2,4]triazine (1) were assigned and the structure of its 2,3‐dimethyl derivative 2 was determined using X‐ray crystallography.
A selective synthesis of 1‐aryl‐3‐quinoxalinyl‐1,2,4‐triazole and furo[2,3‐b]quinoxaline
Authors: Kim Ho Sik , Kurasawa Yoshihisa , Takada Atsushi 
Published: March 2009

AbstractThe reaction of the ester 1 with ethyl benzoate‐2‐diazonium chloride gave the α‐arylhydrazonoester 2b, whose reaction with hydrazine hydrate afforded the α‐arylhydrazonoacylhydrazide 3b. The reaction of 3b with sodium nitrite in water/acetic acid under heating on a boiling water bath provided the 1‐aryl‐3‐quin‐oxalinyl‐1,2,4‐triazole 5b, presumably via the α‐arylhydrazonoacylazide 4b, while the isolation of 4b and then its refluxing in dioxane/water furnished the furo[2,3‐b]quinoxaline 6. The tautomeric behavior of 2b and 3b between the hydrazone imine and diazenyl enamine forms was described together with the tautomer ratio determined by the nmr spectral data.
Tautomeric structure of dihydropyrazolo[1,5‐a]‐pyrimidin‐7‐one in a solution. A facile synthesis of novel 6‐quinoxalinyldihydropyrazolo[1,5‐a]pyrimidin‐7‐ones by ring transformation
Authors: Kurasawa Yoshihisa , Kim Ho Sik , Futatsukawa Rika , Watanabe Chisako , Takada Atsushi , Okamoto Yoshihisa 
Published: March 2009

Abstract6‐Quinoxalinyldihydropyrazolo[1,5‐a]pyrimidin‐7‐ones 4a‐d were synthesized by the ring transformation of 3‐(N,N‐dimethylcarbamoyl)furo[2,3‐b]quinoxaline hydrochloride 5. Compounds 4a‐d were found to exist as the 4,7‐dihydro‐7‐oxo form E in dimethyl sulfoxide based on the nmr spectral data.
Preparation and alkylation of 1,5‐dihydro‐3H‐1,2,4‐thiadiazolo[3,4‐b]quinazolin‐5‐one 2,2‐dioxides
Authors: Demers James P. , Sulsky Richard , Klaubert Dieter H. 
Published: March 2009

Abstract1,5‐Dihydro‐3H‐1,2,4‐thiadiazolo[3,4‐b]quinazolin‐5‐one 2,2‐dioxides (3) are prepared by reaction of isatoic anhydrides with methyl N‐(chloromethanesulfonyl)carbamimidothioate (6). The sodium salt of 3a, generated with sodium hydride in N,N‐dimethylformamide, is alkylated excusively on N‐10. An improved preparation of 6 is described, utilizing a two‐phase sulfonylation.
Quinolizines and indolizines. Part 16. Synthesis of pyrrolo[3,2,1‐ij]quinolin‐4‐ones with potential fungicidal activity
Authors: Kappe C. Oliver , Kappe Thomas 
Published: March 2009

AbstractThe synthesis of some derivatives of 1,2,5,6‐tetrahydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐one (pyroquilon) having potential fungicidal activity has been accomplished starting with readily available 6‐hydroxy‐1,2‐dihydro‐4‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 3, 7. Functionalization in 6‐ or 5‐position gave rise to the corresponding 6‐and 5‐substituted derivatives 8‐12, 17 and 13‐16, 20, 21 respectively. The formation of pyrrolo[3,2,1‐ij]‐pyrano[3,2‐c]quinolines (5, 22, 23) and their degradation to acyl‐substituted derivatives of 7 was studied.
Directed ortho‐lithiation of chloroquinolines. Application to synthesis of 2,3‐disubstituted quinolines
Authors: Marsais F. , Godard A. , Queguiner G. 
Published: March 2009

Abstract2‐, 3‐ and 4‐Chloroquinolines were selectively lithiated at low temperature by lithium diisopropylamide at the more acidic C‐3, C‐4 and C‐3 positions respectively. Reaction of 2‐chloro‐3‐lithioquinoline with electrophiles led to various 2,3‐disubsthuted quinolines. The versatility of this functionalization methodology is enhanced by the C‐2 halogen reactivity towards oxygen or nitrogen nucleophiles. So, a great variety of 2,3‐di‐substituted quinolines were synthesized, such as 2‐chloro, 2‐alkoxy, 2‐aminoquinolines or 2‐quinolones bearing an hydroxy, carbonyl (aldehyde, ketone or carboxylic acid), iodo, trimethylsilyl or boronic acid moiety at the C‐3. Some of the resulting 2,3‐disubstituted synthons were annelated to tetracyclic polyaromatics, which possess the xanthone or indole structure. This could be achieved via further functionalization of the quinoline ring either by SNAr2 or heteroaromatic cross‐coupling reactions, after the first directed‐lithiation step.