bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and DNA‐binding study of A thiazole‐containing analog of netropsin
Authors: Plouvier Bertrand , Houssin Raymond , Bailly Christian , Hénichart Jean‐Pierre 
Published: March 2009

AbstractIn order to study the influence of the nature of the heterocyclic rings of Netropsin (Nt) on the binding to specific nucleotide sequences in the minor groove of DNA, a thiazole‐containing analogue (Thia‐Nt) was designed. Optimized syntheses of the key compound 2‐aminothiazole‐4‐carboxylic acid and Thia‐Nt were reported together with the results of a preliminary study of Thia‐Nt‐DNA binding.
Preparation, proton and carbon‐13 structure determination, and fungicidal activity of chlorinated 1‐arylamino‐1H‐pyrrole‐2,5‐diones
Authors: Yaroslavskym Carmela , Bracha Peretz , Glaser Robert 
Published: March 2009

Abstract1‐(2′,4′‐dichloro)phenylamino‐1H‐pyrrole‐2,5‐dione and 1‐(2′,4′,6′‐trichloro)phenylamino‐1H‐pyrrole‐2,5‐dione were prepared via direct chlorination of 2‐phenyl‐3‐oxo‐6‐hydroxy‐2H‐pyridazine. Both pmr and mass spectroscopy clearly showed that dichloro substitution occurred in the aromatic moiety and not in the vinylic region of the molecule. The former method showed that pyridiazine‐ to pyrrole‐ring isomerization had occurred already at the level of dichlorination. The identical 2′,4′‐dichlorophenyl and 2′,4′,6′‐trichlorophenylpyr‐rolediones were also prepared by reaction of maleic anhydride with the appropriate arylhydrazine. Similar 2′,4‐dichlorophenyl and 2′,4′,6′‐trichlorophenyl analogues were prepared using dichloromaleic anhydride. Cmr spectroscopic techniques were used for pyridazine‐/pyrrole‐ring stereochemical assignment of products derived from dichloromaleic anhydride. 1‐(2′,4′‐dichloro)phenylamino‐1H‐pyrrole‐2,5‐dione and the trichloro‐phenyl analogue were shown to exhibit fungicidal activity in both in‐vivo and in‐vitro assays.
Some acylations of 3‐phenyl and 3‐mesityl‐4,5‐dihydroisoxazoles
Authors: Corsaro Antonino , Chiacchio Ugo , Perrini Giancarlo , Caramella Pierluigi , Albini Franca Marinone 
Published: March 2009

AbstractA study on the acetylation and benzoylation of title compounds by quenching the corresponding 4‐carbanions with acyl chlorides or esters is reported. The obtained ketones are formed as minor regioisomeric adducts in the cycloadditions of benzo and mesitonitrile oxide to methyl and phenyl vinyl ketone. The quenching with methyl chloroformate was also examined as a possible convenient route to 4‐methoxycarbonyl‐3‐aryl‐4,5‐dihydroisoxazoles.
Photochemical methoxy/hydroxymethyl rearrangement in 3‐methoxy‐N‐substituted‐4‐pyriclones
Authors: Stiplošek Z. , Šindler‐Kulyk M. , Jakopĉić K. , Meić Z. , Vikić‐Topić D. 
Published: March 2009

AbstractN‐Substituted 3‐methoxy‐4‐pyridones Ia‐e rearrange to the corresponding N‐substituted 3‐hydroxymethyl‐4‐pyridones IIa‐e when irradiated at 254 or 300 nm in benzene or toluene solution.
Dimerization of pyrazolyl‐5‐hydroxypyrrolidinones to tetrazocines
Authors: Brinkmeyer Raymond S. , Terando Norman H. 
Published: March 2009

AbstractThe dimerization of the hydroxypyrrolidinones 5 and 9 yield the tetrazocines 8 and 11. In addition, in the case of compound 9, the ring‐fused hexaazacyclododecane 12 was isolated. X‐ray diffraction analysis of compound 11 verified the dimeric structure of these products.
Synthesis and identification of 4‐methyl‐N‐(4H‐1,2,4‐triazol‐4‐yl)‐2‐benzothiazolamine, an impurity in the synthesis of tricyclazole
Authors: Dreikorn Barry A. , Unger Paul 
Published: March 2009

AbstractThe synthesis of 4‐methyl‐N‐(4H‐1,2,4‐triazol‐4‐yl)‐2‐benzothiazolamine, 4, a by‐product in the synthesis of tricyclazole, 1, by oxidative cyclization of the corresponding thiourea, 12, with thionyl chloride, is described.
Studies on naphthyridines. Part 2. Synthesis of 4‐substituted and 6‐substituted 1,6‐naphthyridin‐5(6H)‐ones
Authors: Balogh Mária , Hermecz István , Simon Kálmán , Pusztay Levente 
Published: March 2009

AbstractEthyl 4‐substituted 2‐methyl‐5‐oxo‐5,6‐dihydro‐1,6‐naphthyridine‐3‐carboxylates 3a‐h were synthetized in a one‐step reaction from diethyl 2,6‐diraethylpyridine‐3,5‐dicarboxylates 1a‐h by aminomethinylation with 1,3,5‐triazine (2). The 6‐substitued derivatives 6a‐z,aa‐ff could be obtained from diethyl 2‐[2‐(dimethylamino)‐vinyl]‐6‐methylpyridine‐3,5‐dicarboxylate (4) either directly or via the isolated intermediate 2‐[2‐(arylamino)‐vinyl]pyridine compounds 5a‐i.
Pyridazines. L. Syntheses and reactions of phenyl(3‐pyridazinyl)methane derivatives
Authors: Heinisch Gottfried , Huber Thierry 
Published: March 2009

AbstractA convenient approach to phenyl (3‐pyridazinyl) ketone (6) and phenyl(3‐pyridazinyl)methanol (7) is proposed. Reactions of the related diarylmethyl chloride 8 with various N‐ and S‐nucleophiles were found to afford the expected amines 9a‐c, 10a‐c and thioethers 11a,b in satisfactory yields.
Research on heterocyclic compounds. XXIII. Phenyl derivatives of fused imidazole systems
Authors: Abignente E. , De Caprariis P. , Fattorusso E. , Mayol L. 
Published: March 2009

AbstractThe reaction of various heteroarylamines with ethyl 2‐benzoyl‐2‐bromoacetate was used to obtain some imidazo[1,2‐a]pyridines, imidazo[1,2‐a]pyrimidines, imidazo[2,1‐b]thiazoles and imidazo[2,1‐b]benzothiazoles characterized by the presence of a phenyl moiety on the imidazole ring. In the case of thiazole and benzothiazole derivatives, unexpected by‐products were isolated and their structures elucidated.
Synthesis of 3‐benzoyl‐4,7‐dihydro‐7‐oxopyrrolo[3,2‐b]pyridine‐6‐carboxylic acid derivatives as potential antimicrobial agents
Authors: Abdalla Ghassan M. , Sowell J. Walter 
Published: March 2009

AbstractA series of twelve newly synthesized derivations of 3‐benzoyl‐4,7‐dihydro‐7‐oxopyrrolo[3,2‐b]pyridine‐6‐carboxylic acid from 2‐methyl‐3‐benzoyl‐4‐aminopyrrole is reported.
Oxidative halogenation of substituted pyrroles with cu(II). Part I. Bromination of some 3‐acetylpyrroles
Authors: Petruso S. , Caronna S. , Sprio V. 
Published: March 2009

Abstract3‐Acetylpyrroles are brominated with copper(II) bromide. The reaction afforded almost quantitatively only nuclear monobromination. Evidence for the structures of final compounds was by mass spectrometry, 1H‐nuclear magnetic resonance, ir, and elemental analysis.
Synthesis and absorption spectra of 2‐substituted 5,8‐dimethoxy‐4H‐1‐benzothiopyran‐4‐one 1,1‐dioxides
Authors: Watanabe Shigeru , Nakazumi Hiroyuki , Akagi Nobuo , Maeda Katsumi , Kitao Teijiro 
Published: March 2009

Abstract2,3‐Dibromo‐5,8‐dimethoxy‐4H‐1‐benzothiopyran‐4‐one (thiochromone) 1,1‐dioxide which was a starting material to prepare sulfone analogues of 1,4‐naphthoquinone dyes was easily prepared from 5,8‐dimethoxythiochroman‐4‐one by oxidation and bromination. The reactions of 2,3‐dibromo‐5,8‐dimethoxythiochromone 1,1‐dioxide 4 with aliphatic and aromatic amines in ethanol below 20° gave 2‐substituted derivatives 12a‐e and at higher reaction temperature the amination gave 2‐arylamino derivatives 13c‐e debrominated at C‐3. The visible absorption spectra of these derivatives were investigated by the PPP MO method.
Bromination of sydnones. III. Bromination of 3‐(2‐substituted‐phenyl)sydnones and subsequent side chain modification
Authors: Turnbull Kenneth , Blackburn Thomas L. , Esterline Daniel T. 
Published: March 2009

AbstractBromination of the sydnone ring of several ortho‐substituted N‐arylsydnones is reported. Subsequent side‐chain modification generally can be achieved without concomitant removal of the 4‐bromo protective group.
Oxidative halogenation of substituted pyrroles with cu(II). Part II. Bromination of some ethyl 3‐pyrrolecarboxylates and corresponding acids
Authors: Petruso S. , Caronna S. , Sferlazzo M. , Sprio V. 
Published: March 2009

AbstractEthyl 3‐pyrrolecarboxylates and their corresponding acids are brominated with copper(II) bromide. The reaction afforded at 0°, with high‐yield nuclear monobromination.
1,3‐Dipolar cycloaddition reactions of vinylcephalosporins with diazoalkanes
Authors: Pitlik János , Gunda Tamás E. , Miskolczi István 
Published: March 2009

AbstractThe vinylcephalosporin (1) undergoes a regio‐ and stereoselective 1,3‐dipolar cycloaddition with diazomethane to give novel cephalosporins, a 3‐pyrazolinocephem (4) and a double adduct (5). The vinylcephalosporin sulphoxide (2) gives only the pyrazolinocephem (7). In the reaction with diphenyldiazomethane upon heating the initially formed pyrazolines decompose and cyclopropylcephalosporin (9) formation takes place. The determination of the structures and stereochemistry of these compounds is also described.
An unusual HgCl rearrangement in electron impact mass spectrometry of some halomercurioalkyl derivatives
Authors: Ghezzo Elena , Sturaro Alberto , Traldi Pietro , Bravo Pierfrancesco , Viani Fiorenza 
Published: March 2009

AbstractThe electron impact mass spectrometric behaviour of three 2‐methyl‐2‐chloromercuriomethyl‐2,6‐dihydro‐5H‐pyrano[3,2‐c]quinolin‐5‐ones have been studied in detail with the aid of metastable ion data. The primary loss of C4H7, necessarily involving an unusual HgCl rearrangement, is discussed and justified by the formation of a thermodinamically stable Hg‐containing cyclic structure.
Pyridazines. LI. On the Reactivity of Pyridazine‐carbaldehydes towards Selected Active‐Hydrogen Compounds
Authors: Dostal Wolfgang , Heinisch Gottfried , Holzer Wolfgang , Perhauc Ingrid , Zheng Changtu 
Published: March 2009

AbstractReactions of 3‐pyridazinecarbaldehyde and 4‐pyridazinecarbaldehyde with various active methylene carbanions were studied. The products obtained in Knoevenagel reactions, Wittig‐Horner‐Emmons reactions, and Hantzsch‐type reactions are presented.
Polycondensed heterocycles. IV. synthesis of 1,4‐dioxo‐2,3,3a,4‐tetrahydro‐1H‐pyrrolo[2,1‐c][1,4]benzothiazine
Authors: Nacci V. , Campiani G. , Garofalo A. 
Published: March 2009

AbstractA method for the synthesis of the title compound 3 consisted of an intramolecular cyclization in a stannic chloride catalyzed Friedel‐Crafts reaction of N‐(2‐methylthiophenyl)‐5‐oxoproline chloride 10, prepared by chlorination of the corresponding acid 9 obtained by hydrolysis of its ethyl ester 8. Condensation of 2‐methylthioaniline 4 with diethyl bromomalonate 5 afforded diethyl 2‐methylthioanilinomalonate 6 which gave 8 either directly by reaction with ethyl acrylate or by alkylation with ethyl β‐bromopropionate or ethyl acrylate and cyclization of resulting triethyl 2‐(2‐methylthio)anilino‐2‐carboxyglutarate 7. This method was not convenient because of the poor yield of 3 (14%).On the other hand, cyclization of N‐(2‐mercaptophenyl)‐5‐oxoproline 14 with DCC and DMAP provided 3 in 45% yield. Oxidation with m‐CPBA of the esters 11 and 8, demethylation via the Pummerer rearrangement of the respective sulphoxides 12 and 17 with TFAA and oxidation with iodine of resulting N‐(2‐mercap‐tophenyl)‐5‐oxoproline esters 13 and 18 gave the corresponding disulphides 16 and 19. Hydrolysis of these latter compounds and reduction of the resulting bis[2‐[2‐(hydroxycarbonyl)‐5‐oxo‐1‐pyrrolidinyl]phenyl] disulphide 15 with sodium dithionite afforded the required 14. Deprotection of t‐butyl ester 13 with TFA at 55° to obtain 14 led to 3 in 42% yield. Finally the Pummerer rearrangement of N‐(2‐methylsulphinylphenyl)‐5‐oxo‐proline 20 yielded the mixture of 14 and 15.
Synthesis of methyl‐substituted lariat ethers containing a 13‐crown‐4 ring
Authors: Wakita Ryuhei , Yonetani Masayuki , Nakatsuji Yohji , Okahara Mitsuo 
Published: March 2009

AbstractConvenient synthetic procedures for preparing two kinds of methyl‐substituted lariat ethers containing a 13‐crown‐4 ring, 1 and 2, are described. Compounds 1a‐1c were obtained from the reaction of 2‐bromomethyl‐2‐methyl‐13‐crown‐4 (5) with the appropriate alkoxide. Compound 5 was prepared without the need for prior protection of the bromomethyl group. For the synthesis of compounds 2a‐2c, which possess an electron‐donating group on the central carbon of the trimethyl moiety of the 13‐crown‐4 ring, the substituents were introduced before cyclization.
1,3‐Dipolar cycloaddition reactions of 1,3,4‐oxadiazin‐6‐ones with nitrile oxides
Authors: Argyropoulos N. G. , Corobili E. , Terzis A. , Mentzafos D. 
Published: March 2009

Abstract2,5‐Diaryl‐1,3,4‐oxadiazin‐6‐ones 1 gave with nitrile oxides 2 1,2,4‐oxadiazole derivatives 4. When mesitonitrile oxide 2a was used, bis‐adducts 3 were also formed. The cycloadditions showed a remarkable site selectivity towards one carbon nitrogen double bond. The structure of both adducts was fully characterized by X‐ray analysis.
Some transformations of 3‐amino‐4‐alkoxycarbonyl‐6‐hydroxy‐2H‐1‐benzopyran‐2‐ones. The synthesis of [1] benzopyrano[3,4‐d]‐[1,3]oxazine and [1] benzopyrano[3,4‐d]pyrimidine derivatives
Authors: Fajgelj Simona , Stanovnik Branko , Tišler Miha 
Published: March 2009

AbstractAcylation of 4‐alkoxycarbonyl‐3‐amino‐6‐hydroxy‐2H‐1‐benzopyran‐2‐one derivatives 3 and 4 gave under mild conditions the O‐substituted derivatives 5–10, N,O‐disubstituted derivative 11 and N,N‐disubstituted derivative 12. The compound 4 was transformed with benzoyl chloride under more drastic conditions into 13, a derivative of a new heterocyclic system 2‐benzopyrano[3,4‐d][1,3]oxazine. The derivatives of 1‐benzopyrano‐[3,4‐d]pyrimidine 19 and 20 were prepared either from 3 and 4 through the corresponding N‐heteroarylformamidines 14 and 15 and N‐heteroarylformamide oximes 17 and 18 or by cyclization of thiourea derivative 20.
Synthesis,1H,13C‐NMR and mass spectral study of aryloxyquinuclidinium salts
Authors: Cosme A. , Arias M. S. , Gálvez E. , Ruano C. , Ruano C. 
Published: March 2009

AbstractA series of3‐aryl‐3‐hydroxy‐N‐(4′‐aryloxobutyl)quinuclidinium salts have been synthesized. The1H nmr,13C nmr and mass spectra of these compounds are described and discussed.
Electron impact mass spectrometry and collisional spectroscopy in the structural characterization of 4‐benzylidene and 4‐phenylethylidene‐2‐phenyl‐5(4H)‐oxazolones
Authors: Curcuruto O. , Traldi P. , Cativiela C. , De Villegas M. D. Diaz , Garcia J. I. , Mayoral J. A. , Ajò D. 
Published: March 2009

AbstractThe mass spectrometric behaviour of four isomeric oxazolones is rationalized by means of metastable ion studies and bond order calculations via semiempirical methods. The data allow the identification of a possible intermediate structure of molecular species that accounts easily for the observed primary decomposition pathways.
8‐Bromo‐6‐alkylamino‐2‐trifluoromethyl‐9H‐purines with in vitro activity against influenza a virus
Authors: Kelley James L. , Linn James A. , Tisdale Margaret 
Published: March 2009

AbstractSeveral derivatives of 8‐bromo‐6‐dimethylamino‐2‐trifluoromethyl‐9H‐purine (1) were synthesized for structure‐activity relationship studies of anti‐influenza A virus activity. The 8‐bromopurines were prepared by reaction of the anion of the 6‐alkylamino‐2‐trifluoromethylpurines with N‐bromosuccinimide. Several compounds had anti‐influenza activity comparable to ribavirin, but no in vivo activity was observed.
On triazoles XXIII [1]. The reaction of 5‐amino‐1,2,4‐triazoles with thiacyclohexane β‐oxo esters [2]
Authors: Reiter József , Esses‐Reiter Klára 
Published: March 2009

AbstractSix novel isomeric ring systems, namely the thiopyrano[4,3‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidine, the thiopyrano[3,4‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidine, the thiopyrano[3,4‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidine, the thiopyrano[4,3‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidine, the thiopyrano[3,2‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidine and the thiopyrano[2,3‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidine were synthesised. Spectroscopical evidence was given for the structure of compounds obtained.
Homolytic alkylations of substituted pyridazines [1]
Authors: Samaritoni Jack G. , Babbitt George 
Published: March 2009

AbstractThe unsymmetrically substituted pyridazines 1 (X  Ph, CH3) have been found to undergo homolytic heteroaromatic alkylation in moderate to good yields with high regioselectivity. The site of substitution was established by conversion to 5 and measurement of the pyridazine proton coupling constant. In addition, homolytic alkylations of 1 (X  CH3) afforded the N‐alkylated products 6 and 7.
Products from furans. XV. Synthesis of novel tyramine derivatives via 6‐hydroxy‐2H‐pyran‐3(6H)‐ones
Authors: Georgiadis Minas P. , Apostolopoulos Costas D. , Haroutounian Serkos A. 
Published: March 2009

AbstractFuran chemistry was utilized for the synthesis of several novel tyramine derivatives. Thus 2H‐pyran‐3(6H)‐ones were used as keystone intermediates for the preparation of novel α,β‐disubstituted tyramine derivatives. Furthermore by the same approach tyramine was derivatized with a molecule of GABA.
13C NMR investigation of tautomeric and acid‐base equilibria of pyrazolone T and three analogs
Authors: Bell Sandra J. , Mazzola Eugene P. , Dinovi Michael J. , Reynolds William F. , Nielsen Kathy W. 
Published: March 2009

AbstractPyrazolone T and three derivatives have been characterized by 13C and, in part, 15N nmr at several pH values. The 13C chemical shifts have been assigned at, or near, the equivalence points and pKa values of these four compounds. Closely situatued quaternary carbon signals were assigned by means of a heteronuclear chemical shift correlation (FLOCK) experiment which is sensitive to, and was optimized for, 3‐bond C‐H couplings. The 13C chemical shift data indicate the existence of both tautomeric and acid‐base equilibria and demonstrate that the four congeners exist in surprisingly different forms at certain common pH values.
Synthesis and NMR spectroscopy (1H 13C) of 1‐(2′‐benzothiazolyl)‐3(5),4‐polymethylenepyrazoles and related compounds
Authors: Elguero J. , Martinez A. , Singh S. P. , Kumar D. 
Published: March 2009

AbstractA series of 3(5),4‐trimethylene and 3(5),4‐tetramethylenepyrazoles (tetrahydroindazoles) have been prepared from 2‐acylcyclanones using two methods: direct reaction with a substituted hydrazine and through an NH‐pyrazole followed by nucleophilic substitution. The results mainly concern the 2‐benzothiazolyl substituent, but 2,4‐dinitrophenyl derivatives were also studied for comparison. The orientation of the reactions (isomer ratio), the deshielding in 1H nmr of the 5‐methyl and 5‐methylene signals when a benzothiazolyl residue is at position 1, and the ring strain effect on heterocyclic carbons chemical shifts, are discussed.
Synthesis of brain‐targeted 5‐iodo‐, 5‐vinyl‐ and (E)‐5‐(2‐iodovinyl)‐2′‐deoxyuridines coupled to a dihydropyridine ⇌ pyridinium salt redox chemical delivery system
Authors: Kumar Rakesh , Ji Gueijun , Wiebe Leonard I. , Knaus Edward E. 
Published: March 2009

Abstract5‐Iodo‐3′‐O‐(1‐methyl‐1,4‐dihydropyridyl‐3‐carbonyl)‐2′‐deoxyuridine (15a), 5‐vinyl‐3′‐O‐(1‐methyl‐1,4‐di‐hydropyridyl‐3‐carbonyl)‐2′‐deoxyuridine (15b) and (E)‐5‐(2‐iodovinyl)‐3′‐O‐(1‐methyl‐1,4‐dihydropyridyl‐3‐carbonyl)‐2′‐deoxyuridine (15c) were synthesized for future evaluation as lipophilic brain‐selective antiviral agents for the treatment of herpes simplex encephalitis. Quaternization of the 3′‐O‐(3‐pyridylcarbonyl) compounds 10–11 using iodomethane afforded the corresponding 1‐methylpyridinium salts 12–13 which were reduced with sodium dithionite to yield the corresponding 3′‐O‐(1‐methyl‐1,4‐dihydropyridyl‐3‐carbonyl) compounds 14–15.
Intramolecular photoreactions of 4‐(ω‐alkenyloxy)‐6‐methyl‐2‐pyrones
Authors: Shimo Tetsuro , Yasuda Mitsuo , Tajima Jun , Somekawa Kenichi 
Published: March 2009

AbstractPhotoirradiations of 4‐(ω‐alkenyloxy)‐2‐pyrones 1 gave site‐ and regio‐specific intramolecular [2 + 2]‐cycloadducts 2 being oxatricyclic lactones, and/or Dewar‐type valence‐isomer derivatives 4. The reaction path depended upon the alkenyl chain length. Namely the two or three carbon chain gave rise to intramolecular [2 + 2]‐cycloaddition, while the four carbon chain caused both valence‐isomerization and cycloaddition. Hydrolysis of the cycloadducts 2 gave oxabicycloalkanecarboxylic acids 7.
Substituent interaction with ring sulfur in some heterocyclic compounds
Authors: Mckinnon David M. , Abouzeid A. A. 
Published: March 2009

AbstractThe infrared carbonyl absorptions of 7‐acetyl‐1,2‐benzisothiazoles are similar to 7‐acetylbenzo[b]thiophenes, but are lower by approximately 15 cm−1 than the corresponding benzo[b]furans. The reasons for this are discussed.
Photochemical synthesis of 2‐substituted benzothiazoles
Authors: Muthusamy Sengoden , Paramasivam Rangasamy , Ramakrishnan Vayalakkavoor T. 
Published: March 2009

AbstractThe photochemical reaction of 1‐indolethiocarbanilides 1, di‐ and tri‐substituted thioureas 3–5 and 4,4‐di‐methyl‐2,6‐dioxothiocyclohexanecarboxanilides 9 affording the respective benzothiazoles are described.
The convergent syntheses of pyrazinyl and quinoxalinyl phenylmethanones from 2‐lithio pyrazines and quinoxalines
Authors: Ward John S. , Merritt Leander 
Published: March 2009

AbstractPyrazines and quinoxalines bearing 2‐substituents that direct ortho metalation reacted with lithium 2,2,6,6‐tetramethylpiperidide to produce 2‐substituted‐3‐lithiopyrazines and quinoxalines. These lithio reagents reacted with N‐methoxy‐N‐methylbenzamide to give good to moderate yields of 3‐substituted pyrazinyl or quinoxalinylphenylmethanones. The 3‐methylthio substituents of some ketone products were oxidized to methylsulfonyl groups that were susceptible to nucleophilic displacement.
A convenient synthesis of 5,14‐methano‐16‐oxo‐1,5,6‐benzoxadiazonino[3,4‐b]quinoxalines utilizing a 1,3‐dipolar cycloaddition reaction and an intramolecular alcoholysis
Authors: Kurasawa Yoshihisa , Kim Ho Sik , Katoh Ritsuko , Kawano Tae , Takada Atsushi , Okamoto Yoshihisa 
Published: March 2009

AbstractThe reaction of the hydrazones 5a‐c with 2‐chloroacrylonitrile produced the 1,2‐diazepino[3,4‐b]quinoxaline hydrochlorides 6a‐c, which were transformed into the 5,6,7,13‐tetrahydro‐5,14‐methano‐16‐oxo‐1,5,6‐benzoxadiazonino[3,4‐b]quinoxalines 7a‐c, respectively. The oxidation of 7a‐c with diethyl azodicarboxylate afforded the 7,13‐dihydro‐5,14‐methano‐16‐oxo‐1,5,6‐benzoxadiazonino[3,4‐b]quinoxalines 8a‐c, respectively. Compounds 7a‐c and 8a‐c were also obtained by a one‐pot synthesis from 5a‐c and 6a‐c, respectively.
Ozonolysis of 5‐bromo‐ and 5‐ethoxy‐2‐phenyloxazoles. The products and the reaction mechanism
Authors: Kashima Choji , Arao Hideki 
Published: March 2009

AbstractThe ozonolysis of 2‐phenyloxazoles having the good leaving group as an anion at C‐5 position gave mainly N‐benzoylisocyanate (2) with the formation of carbon dioxide.
A simple synthesis of 2(3H)‐benzoxazolones using phenyl chloroformate
Authors: Maleski Robert J. , Osborne C. Edward , Cline Sharon M. 
Published: March 2009

Abstract2(3H)‐Benzoxazolones 3 can be prepared directly from the corresponding 2‐aminophenols and phenyl chloroformate. The intermediate 2‐hydroxy phenylcarbamates 2 are formed easily in aqueous alcohol solvent and these are converted rapidly to product, without their isolation, using one equivalent of sodium hydroxide. The synthesis accommodates a wide variety of substituents, including the easily hydrolyzed ethyl ester.
A facile and novel synthesis of 5‐phenylimidazo[4,5‐c][1,8]naphthyridin‐4(5H)‐ones
Authors: Kuroda Takeshi , Suzuki Fumio 
Published: March 2009

AbstractA convenient and regioselective synthesis of a new heterocycle, 5‐phenyl‐1H or 3H‐imidazo[4,5‐c][1,8]‐naphthyridin‐4(5H)‐one 1‐a or 1‐b, is described. Methyl 2‐anilinonicotinate 15 was transformed into the valuable intermediate, N‐phenyl‐3‐azaisatoic anhydride 4 using trichloromethyl chloroformate (TCF). Treatment of 4 with the anion of ethyl nitroacetate gave 4‐hydroxy‐3‐nitro‐1‐phenyl‐1,8‐naphthyridin‐4(5H)‐one 3. Compound 3 was chlorinated, aminated, reduced, and cyclized to afford 5‐phenylimidazo[4,5‐c][1,8]naphthyridin‐4(5H)‐one 1. Regioselective substitution at the 1 or 3‐position in the imidazole moiety of 1 was achieved by minor changes of the above scheme.