bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxazole ring cleavage in the course of the synthesis of heterocyclic azo dyes
Authors: Savarino P. , Viscardi G. , Carpignano R. , Barni E. 
Published: May 2009

AbstractThe formation of azo dyes by coupling the diazonium salts of aminophenyloxazolopyridines with N,N‐di‐ethylaniline was shown to be a suitable probe to check the stability of the oxazole ring in the course of their preparation. Depending on experimental conditions, “closed” and “opened” systems could be obtained separately.
Development of a new synthesis of 3‐(1H‐tetrazol‐5‐yl)‐4(3H)‐quinazolinone, sodium salt via an amidine intermediate
Authors: Vinogradoff Anna P. , Peet Norton P. 
Published: May 2009

AbstractA new synthesis of the recently reported 3‐(1H‐tetrazol‐5‐yl)‐4(3H)‐quinazolinone, sodium salt (1, MDL‐427), an experimental mediator release inhibitor, was developed from: (1) reaction of 5‐aminotetrazole 3 and triethyl orthoformate 6 to give ethyl N‐(1H‐tetrazol‐5‐yl)formimidate 8, (2) reaction of methyl anthranilate and imidate 8 to give amidine 11, and (3) treatment of 11 with base to give 1. Investigation of each of these steps independently led to a significantly more efficient, facile and higher‐yielding 1‐pot process. A brief examination of anthranilic acid 13 and its salts and derivatives 14 to 17 in this process found them to have dissimilar reactivities. The formation of amidine 11 as an isolable intermediate was unusual, as was its failure to cyclize under standard neutral or acidic conditions. The absolute requirement for base to effect cyclization of 11 appears to be unprecedented.
Heterocyclic variants of the 1,5‐benzodiazepine system. V. Derivatives of 2‐(ortho‐R1‐anilino)‐4‐(p‐R2‐phenyl)‐3H‐1,5‐benzodiazepines
Authors: Conés Eduardo , Martínez Roberto , Ceballos Irma 
Published: May 2009

AbstractMono‐N‐methylation of 2‐(ortho‐R1‐anilino)‐4‐(p‐R2‐phenyl)‐3H‐1,5‐benzodiazepines IV is achieved in moderate yield with sodium hydride in methyl iodide. Reaction of the N‐methyl derivatives I with methoxyacetyl chloride gave the compounds II and III. The structure of all products was confirmed by ir, 1H‐nmr and mass spectrometry.
Reduction of n‐(1,3‐dioxolan‐2‐yl)‐1‐methylpyridinium ions: Molecular structure of the 4‐(l,3‐dioxolan‐2‐yl)‐1‐methyl‐1,2,3,6‐tetrahydropyridine‐borane complex
Authors: Rodriguez J. G. , Martinez‐Lopez N. , De Lerma J. Lopez , Perales A. 
Published: May 2009

AbstractThe reduction of the n‐(1,3‐dioxolan‐2‐yl)‐1‐methylpyridinium ions with sodium borohydride has been studied to prepare N‐methylformylpiperidines. Deuterium oxide was used as the solvent in order to assign the protons in the nmr spectra. As a product of the reaction, the 4‐(1,3‐dioxolan‐2‐yl)‐1‐methyl‐1,2,3,6‐tetrahy‐dropyridine‐borane complex, was isolated and crystallized. A X‐ray study of this borane complex has been carried out.
A lithiation approach to cordycepin analogues variously substituted at the C‐8 position
Authors: Hayakawa Hiroyuki , Tanaka Hiromichi , Sasaki Keiko , Haraguchi Kazuhiro , Saitoh Takafumi , Takai Fumi , Miyasaka Tadashi 
Published: May 2009

AbstractSeveral 8‐substituted cordycepins were prepared via LDA lithiation of 2′,5′‐bis‐O‐(t‐butyldimethylsilyl)‐cordycepin and successive reactions of its C‐8 lithiated species with various types of electrophiles. Wittig reaction of the 8‐formyl derivative was also examined.
The synthesis of monomethoxy‐6‐methyl‐7H‐indeno[2,1‐c]quinolines
Authors: Quraishi Mumtaz A. 
Published: May 2009

AbstractA series of monomethoxy‐6‐methyl‐7H‐indeno[2,1‐c]quinolines has been prepared by cyclization of the appropriate 1,3‐dioxoindan‐2‐yl‐ethylideneanilines, followed by Wolff‐Kishner reduction.
A synthetic entry into the quino[2,1‐b][1,3]benzoxazine ring system
Authors: Aversa M. C. , Bonaccorsi P. , Giannetto P. 
Published: May 2009

AbstractThe double ring closure of N‐(2‐hydroxybenzyl)anthranilic acids 1 with acetic anhydride or its acyclic analogous (RCH2CO)2O 2b and 2e lead to the formation of novel 12H‐quino[2,1‐b][1,3]benzoxazin‐5‐ones. The structure of the obtained compounds was proved with the use of their ir, mass, 1H and 13C nmr spectra. Homo‐ and heteronuclear two‐dimensional nmr experiments were performed to unambiguously assign all proton and carbon chemical shifts.
1,3‐Dipolar cycloaddition of nitrile oxides to N‐vinylcarbazole: Regioselective formation of 5‐(9‐carbazolyl)‐Δ2‐isoxazolines
Authors: Rao K. Rama , Nageswar Y. V. D. , Sattur P. B. 
Published: May 2009

AbstractAryl substituted nitrile oxides undergo 3 + 2 cycloaddition to N‐vinyl carbazole to afford only one regioisomer, i.e., 3‐aryl substituted 5‐(9‐carbazolyl)‐Δ2‐isoxazolines III in good yield.
Synthesis of new arylbenzofurodiazepin‐6‐ones
Authors: Viti Giovanni , Giannotti Danilo , Nannicini Rossano , Ricci Renzo , Pestellini Vittorio 
Published: May 2009

AbstractTwo new tetracyclic structures, containing the diazepine ring, were synthesized: 5,6‐dihydro‐12H‐benzofuro[3,2‐b][1,5]benzodiazepin‐6‐one and 5,6‐dihydro‐12H‐benzofuro[3,2‐b]pyrido[3,2‐f][1,5]diazepin‐6‐one. Thus N‐(2‐haloaryl)‐2‐[(2‐cyanophenyl)oxy]acetamides were cyclized to the corresponding N‐(2‐haloaryl)‐3‐amino‐2‐benzofurancarboxamides and then, through the formation of the central diazepine ring, to the title compounds. Formation of the diazepine ring took place only when an electron‐withdrawing group was present in the molecule to facilitate the nucleophilic attack of an amine in the benzofuran intermediate.
Isoindole derivatives from o‐diacylbenzenes and aromatic amines
Authors: Nan'ya Seiko , Fujii Takashi , Butsugan Yasuo 
Published: May 2009

Abstracto‐Acetylbenzophenone produced yellow 1,2‐diaryl‐3‐(aryliminomethyl)isoindole by the reaction with aromatic amines in the absence of acid. On the reaction of o‐diacetylbenzene under the similar condition, three types of yellow products were obtained. The structures of these isoindole derivatives were determined and their formation mechanism was proposed.
Double 1,3‐dipolar cycloadditions of meso‐ionic heterocycles to N‐substituted maleimides
Authors: Nan'ya Seiko , Kurachi Yoshinori , Butsugan Yasuo 
Published: May 2009

AbstractDouble 1,3‐dipolar cycloadditions of 2,4‐diphenyl‐3‐methyloxazotium 5‐oxide and 3‐phenylsydnone to two molecules of N‐substituted maleimide afforded one or two isomeric 4,8‐iminobenzo[1,2‐c:4,5‐c′]dipyrrole‐1,3,5,7‐tetrone derivatives owing to the types of heterocycles as well as N‐substituents of maleimides.
Synthesis, crystal structure determination and pharmacological activity of 7,8,3′,4′‐tetramethoxyisoflavone
Authors: Domínguez Esther , Lete Esther , Villa María‐Jesús , Igartua Amaia , Sotomayor Nuria , Arrieta Juan M. , Berisa Agustin , Labeaga Luis , Orjales Aurelio , Germain Gabriel , Nastopoulos Vassilios 
Published: May 2009

Abstract7 The8,3′,4′‐tetramethoxyisoflavone2was synthesized and its structure confirmed by X‐ray crystallographic analysis. Pharmacological screening was carried out with this compound in order to assess its pharmacological profile. Isoflavone2possessed antiinflamatory activity in the carrageenan oedema test, with a dose‐effect relationship comparable to that of hydroxylated flavonoids. It is noteworthy that2is one of the few isoflavones efficient as antiinflammatory with complete alkylation of hydroxyl groups.
Synthesis of novel indolizine derivatives
Authors: Bonnaud Bernard , Bigg Dennis , Patoiseau Jean‐François 
Published: May 2009

AbstractThe reaction of a number of γ‐butyrolactones with azole anions is shown to give γ‐substituted butanoic acids in moderate to good yields. The pyrrolyl and indolylbutanoic acids obtained underwent cyclization in a simple one‐pot procedure employing ethyl chloroformate and boron trifluoride etherate. Some aspects of the chemistry of the resulting indolizin‐8‐ones are described.
Diels‐alder reaction of (E)‐4‐(2‐nitroethenyl)‐1H‐imidazoles and methyl (E)‐3‐(1‐imidazol‐4‐yl)propenoates
Authors: Kosaka Keigo , Maruyama Kazumi , Nakamura Haruko , Ikeda Masazumi 
Published: May 2009

AbstractDiels‐Alder reaction of methyl (E)‐3‐(1H‐imidazol‐4‐yl)propenoates 2, 3a‐c and (E)4‐(2‐nitroethenyl)‐1H‐imidazoles 3d,e with 2,3‐dimethyl‐1,3‐butadiene, cyclopentadiene, and cyclohexa‐1,3‐diene gave the corresponding cycloadducts 6–9.
Synthesis of 7‐ethyl‐4,7‐dihydro‐4‐oxo‐2‐(4‐pyridinyl)thieno[2,3‐b]pyridine‐5‐carboxylic acid
Authors: Bacon Edward R. , Daum Sol J. 
Published: May 2009

Abstract7‐Ethyl‐4,7‐dihydro‐4‐oxo‐2‐(4‐pyridinyl)thieno[2,3‐b]pyridine‐5‐carboxylic acid (4), an analog of nalidixic acid, was synthesized in seven steps starting from commercially available 4‐methylpyridine. Bacterial susceptibility to compound 4 was tested and the title compound was found to exhibit only weak antibacterial activity against a variety of pathogens including S. Aureus, E. Coli and P. Aeruginosa.
The structure of β‐heteroaryl‐α,β‐dehydro‐α‐amino acid derivatives, intermediates in the synthesis of fused pyran‐2‐ones. Substituted methyl (Z)‐2‐benzoylamino‐3‐(5‐oxopyrazolinyl‐4)propenoates
Authors: Stanovnik Branko , Golič Ljubo , Kmecl Primož , Ornik Brina , Svete Jurij , Tišler Miha 
Published: May 2009

AbstractIt was shown by some chemical transformations that β‐heteroaryl‐α,β‐dehydro‐α‐amino acid derivatives 3 and 7, obtained from pyrazolone derivatives 1 or 6 and 2, exist in Z‐forms. The structure of 7 was confirmed by X‐ray analysis.
Hydroxyindole intermediates in the process of melanogenesis: A mass spectrometric study
Authors: Costa Carlo , Bertazzo Antonella , Allegri Graziella , Catinella Silvia , Traldi Pietro 
Published: May 2009

AbstractStudies on the enzymatic formation of polymers from hydroxyindoles are described.FAB analysis of the reaction mixtures followed by collisional spectroscopy of the most abundant ionic species was applied to analyze products obtained from the reaction catalyzed by tyrosinase on 4‐ or 5‐hydroxyindole at different times.Results suggest that moieties of the precursors are still present in the oligomeric systems. Among the reaction products dimeric and trimeric compounds were detected by Fast Atom Bombardment and their structure assignment was achieved by collision spectroscopy.
The base‐promoted dehydration of rac.‐trans‐tetrahydro‐6‐hydroxy‐4‐[(2‐(dimethylamino)ethyl]‐7‐(4‐methoxyphenyl)‐1,4‐thiazepin‐5(2H)‐one
Authors: Mohacsi Erno , O'Brien Jay P. 
Published: May 2009

AbstractThe base‐catalyzed alkylation of rac.‐trans‐tetrahydro‐6‐hydroxy‐7‐(4‐methoxyphenyl)‐1,4‐thiazepin‐5(2H)‐one (1) with dimethylaminoethyl chloride in dimethyl sulfoxide provided predominantly rac.‐trans‐tetrahydro‐6‐hydroxy‐4‐[(2‐dimethylamino)ethyl]‐7‐(4‐methoxyphenyl)‐1,4‐thiazepin‐5(2H)‐one (2) and in addition, 2,3‐dihydro‐4‐[2‐(dimethylamino)‐ethyl]‐7‐(4‐methoxyphenyl)‐1,4‐thiazepin‐5(4H)‐one (3). A plausible mechanism is postulated for the dehydration of the rac.‐trans‐amide 2.
Synthesis of pyrazole analogues of isoaptazepine
Authors: Massa Silvio , Artico Marino , Mai Antonello , Mancuso Antonella , Corelli Federico 
Published: May 2009

AbstractThe synthesis of the novel tetracyclic rings 5 and 6 is described starting from 4‐cyano‐1‐methyl‐5(1H‐pyrrol‐1‐yl)‐1H‐pyrazole and its 3‐(1H‐pyrrol‐1‐yl)‐ isomer, respectively. The pathway employed is based on a one‐pot double annelation reaction involving the transformation of 13 into the required tetracyclic derivative 16. Lithium aluminum hydride/sulfuric acid reduction of the last compound furnished 5. A similar way was used for the synthesis of 6 by cyclization of 20.
The reformatsky reaction of 1‐acyl‐3,5‐dimethylpyrazoles. A convenient preparation of 4‐amino‐3‐oxoalkanoic acid derivatives
Authors: Kashima Choji , Kita Isanobu , Takahashi Katsumi , Hosomi Akira 
Published: May 2009

AbstractThe conversion of N‐acylpyrazoles into β‐keto esters was accomplished efficiently by the treatment with α‐bromo esters and zinc dust. Using this Reformatsky reaction of N‐acylpyrazoles, 4‐(protected amino)‐3‐oxoalkanoic acid derivatives were conveniently prepared as the key intermediates in the synthesis of statines.
Haloacetylated enol ethers: 3. Synthesis of 3,3a,4,5,6,7‐hexahydro‐3‐halomethylbenzoisoxazoles
Authors: Martins Marcos A. P. , Flores Alex F. C. , Freitag RogŔRio , Zanatta Nilo 
Published: May 2009

AbstractThe investigation of the halomethyl group effect on the regiochemistry of the reaction of 2‐acetylcyclo‐hexanones 1a‐d and β‐methoxyvinyl trifluoro methyl ketone derivative 2a with hydroxylamine to afford 3,3a,4,5,6,7‐hexahydro‐3‐halomethyl‐3‐hydroxy[2,1]benzoisoxazoles 3a‐c, and the respective dehydrated compounds 4a‐c, is reported. Compounds 1a‐c, 2a proved to be versatile building blocks for the regiospecific synthesis of isoxazole derivatives having a 3‐halomethyl substituent, in good yields.
Synthesis of 3‐dialkylaminomethyl‐5‐methyl‐4‐substituted‐1H‐pyrazoles. Selective functionalization of one methyl group via n‐nitration of 3,5‐dimethyl‐4‐substituted‐1H‐pyrazoles
Authors: Lammers H. , Vollinga R. , Zandbergen P. , Cohen‐Fernandes P. , Habraken C. L. 
Published: May 2009

AbstractTreatment of 4‐substituted 3,5‐dimethyl‐1‐nitro‐1H‐pyrazoles 1 and 10a‐c with secondary amines in acetonitrile, in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), affords the novel dialkyl‐aminomethyl‐1H‐pyrazoles 5, 6, 7, 8, 11a‐c, 12a‐c and 13a‐c in good to excellent yields. In this way one of the, in general, inert methyl groups of 3,5‐dimethyl‐4‐substituted‐1H‐pyrazoles is functionalized creating a new synthetic route to azoles containing a coordinating substituent.
Polychlorination of thiophene. A reinvestigation
Authors: Temciuc Marcel , Hörnfeldt Anna‐Britta , Gronowitz Salo 
Published: May 2009

AbstractSome old controversies in the literature with regard to the structures of trichlorothiophenes have been elucidated. In the course of these studies, we found that the best method for the preparation of 2,3,5‐trichlorothiophene is the direct chlorination of thiophene in the presence of catalytic amounts of ferric chloride. If 2,5‐dichlorothiophene is available 2,3,5‐trichlorothiophene can also be obtained in good yields through chlorination with thionyl chloride and sulfuryl chloride, using aluminum trichloride as catalyst.
Studies on intramolecular nh‐bridging in aromatic compounds. Part 3 [1–3]
Authors: Horaguchi Takaaki , Klemm L. H. , Norris Eric S. 
Published: May 2009

AbstractA study was made of the use of calcium oxide as a catalyst at a temperature of 400–700° for the dehy‐drocyclization of four primary arylamines: 2‐aminobiphenyl, 1‐aminotriphenylene (5c), 2‐phenoxyaniline, and N‐(2‐aminophenyl)pyrrole. Maximal yields of cyclized products isolated were 53% (carbazole), 52% (4H‐naphtho[1,4‐def]carbazole), 18% (phenoxazine), and 0%, respectively. Comparison is made with reported cyclizations of the corresponding nitro and azido starting materials. In one case, treatment of I‐nitrotriphenylene with triethyl phosphite produced mainly diethyl N‐(1‐triphenylenyl)phosphoramidate (51%). Mono‐ and hemihydrochlorides of 5c are described. A mechanism for the catalyzed dehydrocy‐clization is proposed.
Regioselective synthesis of 6‐alkylated lumazine derivatives
Authors: Igarashi Mamoru , Tada Masaru 
Published: May 2009

AbstractThe regiospecific synthesis of alkylated lumazines is achieved by hetero Diels‐Alder addition between an oxadiazinone 2 and enamine. The reactions proceed stepwise by cycloaddition, decarboxylation and deamination to produce the 6‐alkylated lumazines.
On the metalation of 4‐substituted pyridazines
Authors: Turck Alain , Plé Nelly , Mojovic Ljubica , Ndzi Bruno , Quéguiner Guy , Haider Norbert , Schuller Herbert , Heinisch Gottfried 
Published: May 2009

AbstractA series of new pyridazines bearing ortho‐directing groups at C‐4 (protected/activated amino or carboxylic acid functionalities) was prepared and their metalation with lithium 2,2,6,6‐tetramethylpiperidide was studied. Reactions of the ortho‐lithiated species thus obtained with aldehydes as electrophiles opens an access to 4,5‐disubstituted pyridazines 3, 4, 14, and 15.
The synthesis and transformations of ethyl (Z)‐2‐[2,2‐bis(ethoxycarbonyl)vinyl]amino‐3‐dimethylaminopropenoate, a new reagent in the synthesis of heterocyclic compounds
Authors: Soršak Gorazd , Sinur Amalija , Golič Ljubo , Stanovnik Branko 
Published: May 2009

AbstractEthyl (Z)‐2‐[2,2‐bis(ethoxycarbonyl)vinyl]amino‐3‐dimethylaminopropenoate (5), a new reagent in the synthesis of heteroaryl substituted β‐amino‐ α,β‐ ‐dehydro—amino acid derivatives and some fused hetero‐cyclic systems, was prepared from ethyl N‐2,2‐bis(ethoxycarbonyl)vinylglycinate (3) and N,N‐dimethyl‐formamide dimethyl acetal (4). The substitution of the dimethylamino group in the compound 5 with heterocyclic amines produced ethyl 2‐[2,2‐bis(ethoxycarbonyl)vinyl]amino‐3‐heteroarylaminopropenoates 7a‐f and, in some instances, [2,2‐bis‐(ethoxycarbonyl)vinyl]aminoazolo‐ or ‐azinopyrimidine derivatives 8g‐k.
Synthesis of fused purinoquinazolines. Three new heterocyclic ring systems
Authors: Da Settimo Antonio , Primofiore Giampaolo , Cristina Bertacchi Maria , Da Settimo Federico , Marini Anna Maria 
Published: May 2009

AbstractThe Ullmann reaction of 8‐aminotheophylline or 8‐aminocaffeine with 2‐chlorobenzoic acid and of 8‐bromotheophylline with ethyl‐2‐aminobenzoate afforded derivatives of three new heterocyclic systems: purino[7,8‐α]quinazoline‐5,9,11(6H,8H,10H)‐trione, purino[8,9‐b]quinazoline‐2,4,11(1H,3H,5H)‐trione and purino[8,7‐b]quinazoline‐2,4,6(1H,3H,11H)‐trione, respectively.
Synthesis and reactivity of 2,6‐diamino‐4‐methyl‐3‐pyridinecarbonitrile
Authors: Katritzky Alan R. , Rachwal Stanislaw , Smith Terrance P. , Steel Peter J. 
Published: May 2009

Abstract2,6‐Dihydroxy‐4‐methyl‐3‐pyridinecarbonitrile is converted via its 2,6‐dichloro analog into the corresponding 2‐amino‐6‐chloro, 2‐chloro‐6‐amino, and 2,6‐diamino derivatives. The last reacts with benzene‐sulfonyl chloride to yield a tris‐sulfonyl derivative, the structure of which is demonstrated by X‐ray analysis.
Synthesis of 3‐aminorhodanine derivatives as aldose reductase inhibitors
Authors: Hanefeld Wolfgang , Schlitzer Martin 
Published: May 2009

AbstractA number of 5‐condensated 3‐acylaminorhodanines3was prepared as potential inhibitors of the aldose reductase by acylation of the amino group of 3‐aminorhodanine1and subsequent condensation of the 5‐methylene function with appropriate aldehydes. Some of these compounds displayed interesting activity.
Heterocyclic variants of 1,5‐Benzodiazepine system. VII. Synthesis of substituted 2a‐Phenyl‐4‐methylsulfonyl‐2‐methoxy‐1,2,2a,3‐tetrahydroazeto[1,2‐a][1,5]benzodiazepin‐1‐ones
Authors: Martínez Roberto , Hernández Paulina E. , Angeles Enrique 
Published: May 2009

AbstractThe preparation of novel 2a‐phenyl‐4‐methylsulfonyl‐2‐methoxy‐1,2,2a,3‐tetrahydroazeto[1,2‐a][1,5]‐benzodiazepin‐1‐ones is described. The structure of all the products was corroborated by ir, mass spectrometry and 1H and 13C‐nmr.
Condensation reactions of 3‐Amino‐4‐imino‐4H‐thieno‐[3,4‐c][1]benzopyran
Authors: Nyiondi‐Bonguen E. , Sopbué Fondjo E. , Fomum Z. Tanee , Döpp Dietrich 
Published: May 2009

AbstractThe title compound 1 reacts with trifluoroacetic anhydride to give the doubly trifluoracetylated derivative 2 and in addition the coumarin derivative 3. In refluxing DMF, two moles of 1 react with loss of one molecule of ammonia to afford 4, which undergoes subsequent N‐acylation by β‐dicarbonyl compounds 9a‐f to yield N‐acyl derivatives 10a‐f. With dimethyl malonate (9a) besides compound 10a, the cycloacylated compound 11 was also obtained in good yield. Compound 11 is readily hydrolysed and decarboxylated with both acid and alkali to the previously described fused derivative 12. The latter may be converted into the new thienopyrimidinone derivative by action of aqueous alkali.
Synthesis and reactions of some 4‐heteroaryl‐3‐nitrocoumarins—
Authors: Govori S. , Rapic V. , Led O. , Čačić M. , Tabaković I. 
Published: May 2009

AbstractBy the action of 2‐aminothiazole, 2‐aminopyridines, and 2‐aminopyrimidines, respectively, on 4‐chloro‐3‐nitrocoumarin (3) the corresponding 4‐heteroarylamino‐3‐nitrocoumarins 5–7 have been isolated in very good yields. Reactions of coumarins 6 and 7 with either aqueous tetrabutylammonium bisulfate/sodium hydroxide in a two phase system or 5% aqueous sodium hydroxide have been studied.
A facile conversion of ethoxydihydropyrans to 4‐cyanoethylisoxazoles
Authors: Yamauchi M. , Akiyama S. , Watanabe T. , Okamura K. , Date T. 
Published: May 2009

AbstractThe reaction of ethoxydihydropyrans 2, which were prepared from 2‐methylene‐1,3‐dicarbonyl compounds 1 with ethyl vinyl ether, and hydroxylamine hydrochloride gave 4‐cyanoethylisoxazoles 3 whose substituents at the 3 and 5 positions were transformed from substituent at the 2 position and the acyl group of 2 regioselectively.
Friedländer reaction of 3‐acetyltropolones: Synthesis of naphthyridinyl‐ and allied heterocyclic‐substituted tropolones
Authors: Piao Ming‐Zhu , Imafuku Kimiaki 
Published: May 2009

AbstractFive 3‐acetyltropolones reacted with 2‐amino‐3‐pyridinecarbaldehyde to afford the corresponding 3‐(1,8‐naphthyridin‐2‐yl)tropolones in excellent yields. In a similar manner, 1,6‐naphthyridin‐2‐yl‐,1,7‐naphthyridin‐2‐yl‐, 6‐pyrido[2,3‐b]pyrazinyl‐, and 1‐methyl‐6‐pyrazolo[5,4‐b]pyridyl‐substituted tropolones were prepared. Reactivities of amino‐substituted heteroarenecarbaldehydes in these reactions and properties of the products are also discussed.
Synthesis and stereochemical assignment of 7‐arylidene and 7‐heteroarylidene morphinan‐6‐ones
Authors: Nan Yang , Upadhyaya Subhash P. , Xu Wei , Hughes Kathrine E. , Dunn William J. , Bauer Ludwig , Bhargava Hemendra N. , Doss George A. 
Published: May 2009

AbstractA number of (E)‐7‐arylidenenaltrexones were synthesized by azeotropic distillation of water from a benzene solution of naltrexone and an aromatic aldehyde (benzaldehyde, 4‐chloro‐ and 4‐fluorobenzaldehyde, 3‐and 4‐pyridinecarboxaldehyde and 1‐methyl‐2‐imidazolecarboxaldehyde) using piperidine as a catalyst. In addition, (E)‐7‐benzylidenenaloxone was prepared by the previously published Claisen‐Schmidt condensation using sodium hydroxide in methanol. The stereochemistry of these arylidene derivatives 3–9 was determined to be (E) by means of nuclear Overhauser enhancement experiments. The 13C nmr spectra of (E)‐3–9 are recorded in deuteriochloroform and those of the hydrochlorides in deuteriodimethyl sulfoxide.
Synthesis of pyrimidines from 3‐trifluoromethylsulfonyl‐oxypropeniminium triflates and nitriles; molecular and crystal structure of the 1:1 and 1:2 Adducts of a 4‐(2‐diethylaminovinyl)pyrimidine with triflic acid
Authors: Rahm Rainer , Maas Gerhard 
Published: May 2009

AbstractThe 3‐trifluoromethylsulfonyloxy‐1‐hexeniminium triflate 1 reacts with two equivalents of an aliphatic nitrile or of benzonitrile to give the 4‐(2‐diethylaminovinyl)pyrimidinediium bis(triflates) 4, which can be deprotonated to give the monoprotonated or neutral pyrimidines 5 and 6, respectively. When the related 1‐phenyl‐substituted iminium salt 7 is heated in acetonitrile at 140°, 1,5‐cyclization of the cation leading to indane derivative 8 competes with formation of the pyrimidinium salt 9. X‐ray crystal structure determination reveals significant differences in the bond lengths of mono‐and diprotonated 4‐(2‐diethylaminovinyl)pyrimidines 5a and 4a.
Study on the preparation of heteroaryl substituted enamines. A simple synthesis of heteroaryl substituted acetaldoximes from enamines
Authors: Antončopar  , Stanovnik Branko , Tišler Miha 
Published: May 2009

AbstractA comparative study of the reactivity of methyl groups towards N, N‐dimethylformamide dimethyl acetal and tert‐butoxybis(dimethylamino)methane was carried out on methyl substituted six‐membered nitrogen containing heterocycles 1 to give enamines 2, which were easily transformed to oximes by treating with hydroxylamine hydrochloride in methanol. Most of them were isolated as (E, Z)‐oximes of heteroarylacetaldehyde (11), but 5‐(1,2,4‐triazinyl) substituted derivatives as (E, Z)‐oximes of 2,5‐dihydro‐1,2,4‐triazin‐(Z)‐5‐ylideneacetaldehyde (11t, 11u, and 12). Oximes were finally transformed to the corresponding acetonitriles 16 and 3‐(dimethylamino)acrylonitriles 17.