bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaction of 1,3,4‐oxadiazolones with free L‐α‐amino acids: A facile synthesis of novel 3,5‐disubstituted hydantoins
Authors: Saegusa Yasuo , Harada Shigeo , Nakamura Shigeo 
Published: March 2009

AbstractA series of novel 3,5‐disubstituted hydantoins 3a‐1 were easily synthesized in one‐step from the reaction of 2‐phenyl‐1,3,4‐oxadiazolin‐5‐ones 1a‐h with various free L‐α‐amino acids 2a‐e in m‐cresol at 150°. An alternative route leading to the formation of 3‐benzamido‐5‐isopropylhydantoin 3c was also developed to make clear the reaction mechanism.
Chemistry of thienopyridines. XXXVII. Syntheses in the cyclopenta, cyclohexa‐, and cycloheptathieno[2,3‐b]pyridine series. Three analogs of 9‐amino‐1,2,3,4‐tetrahydroacridine
Authors: Klemm L. H. , Wang Jun , Sur Sandip K. 
Published: March 2009

Abstract4‐Aminocyclopenta‐, 4‐aminocyclohexa‐, and 4‐aminocycloheptathieno[2,3‐b]pyridines were synthesized in very low overall yield by four‐step procedures starting from bis(2‐thienylammonium) hexachlorostannate(IV) and 2‐hydroxymethylenecyclopentanone, 2‐methoxymethylenecyclohexanone, and 2‐hydroxymethylenecycloheptanone, respectively.
Stereoselective ring closure of 6‐[[(methylamino)carbonyl]oxy]‐2H‐pyran‐3(6H)‐ones. Formation of the 5H‐pyrano[3,2‐d]oxazole‐2,6‐dione ring system
Authors: Georgiadis Minas P. , Couladouros Elias A. 
Published: March 2009

AbstractThe stereospecific formation of the 5H‐pyrano[3,2‐d]oxazole‐2,6‐dione ring system from 2,2‐disubstituted‐6‐[[(methylamino)carbonyl]oxy]‐2H‐pyran‐3(6H)‐one via an enolization at C‐5 is presented. The outcome of the same reaction in the case of 2‐monosubstituted 2H‐pyran‐3(6H)‐ones is also discussed.
The synthesis of ring‐expanded analogues of xanthine containing the imidazo[4,5‐e][1,4]diazepine ring system
Authors: Hosmane Ramachandra S. , Bhan Anila 
Published: March 2009

AbstractThe synthesis of 4,5,7,8‐tetrahydro‐6H‐imidazo[4,5‐e][1,4]diazepine‐5,8‐dione and its several 1‐ and 3‐alkyl (aralkyl) derivatives 2 has been reported. Mechanistic explorations of the final synthetic step as well as structural confirmation of a final product 2d by single‐crystal X‐ray diffraction analyses have also been presented.
Some fatty acids having an O‐heterocycle in their terminal positions. I. ω‐(3‐Chromonyl)alkanoic acids
Authors: Yamaguchi Seiji , Mutoh Masao , Shimakura Masaaki , Tsuzuki Kunihiro , Kawase Yoshiyuki 
Published: March 2009

AbstractSome ω‐(3‐chromonyl)alkanoic acid derivatives, 1a and 2a, n = 4, 5; 3a, 4a and 5a, n = 2‐6, were synthesized by cyclization of corresponding methyl ω‐(2‐hydroxybenzoyl)alkanoates 7b or ethyl ω‐(2,4‐dihydroxybenzoyl)alkanoates 8b with N,N‐dimethylformamide‐dimethyl acetal or acetic anhydride‐DBU followed by hydrolysis.
Preparation of 9‐aryl (or heteroaryl)methylidene‐10‐(methoxyimino)‐phenanthrenes and their thermal electrocyclisation to fused quinolines
Authors: Nicolaides Demetrios N. , Litinas Konstantinos E. , Papageorgiou Georgios K. , Stephanidou‐Stephanatou Julia 
Published: March 2009

Abstracto‐Quinone methanide N‐methoxyimines 6a‐c, 7a‐c, 11a‐b and 12a, easily prepared from the reaction of 10‐(methoxyimino)phenanthrene‐9‐one (3) with phosphonium salts 5a‐c, 10a‐b in the presence of lithium hydroxide, are thermally converted into dibenzo[f,h]quinolino[2,3‐x]fused compounds 9a‐c and 13a‐b, in high yield.
Synthesis and reaction of 2‐imino‐1,3‐thiazetidines and 2‐imino‐1,3‐dithietanes
Authors: Okajima Nobuyuki , Okada Yoshiyuki 
Published: March 2009

Abstract2‐Imino‐1,3‐thiazetidines and 2‐imino‐1,3‐dithietanes were synthesized and their reactivities were studied. The former readily underwent ring‐opening reaction with amines to yield guanidine derivatives. The reaction products were applied to the synthesis of heterocycles such as triazoles and triazines. The latter was converted to isothiocyanate by the reaction of m‐chloroperbenzoic acid.
Ladder oligophenothiazines by direct thionation of N‐Arylanilino Derivatives
Authors: Andreani Franco , Bizzarri Paolo Costa , Casa Carlo Delia , Fiorini Maurizio , Salatelli Elisabetta 
Published: March 2009

AbstractLadder oligophenothiazines were synthesized by direct catalyzed insertion of elemental sulfur in anilino‐substituted phenothiazines and para‐oligoanilines. The starting 3‐ and 3,7‐anilino derivatives of phenothiazine were prepared with improved selectivities and yields by new syntheses. The oxidability of the oligomers is discussed.
A novel method for the synthesis of 4‐isoquinolinols
Authors: Uno Hidemitsu , Okada Shin‐Ichiro , Suzuki Hitomi 
Published: March 2009

Abstract1‐Substituted 1,2‐dihydroisoquinolines, derived from isoquinoline and organolithium reagents, readily undergo autoxidation to lead to 4‐isoquinolinols in moderate yields.
The syntheses of 4b,5a‐dihydrodibenz[3,4:5,6]anthra[1,2‐b]oxirene and 4b,5a‐dihydro‐5H‐dibenz[3,4:5,6]anthra[1,2‐b]azirine
Authors: Abu‐Shqara Elias , Blum Jochanan 
Published: March 2009

AbstractThe syntheses of the K‐oxide and K‐imine derivatives of dibenz[a,j]anthracene (1) are described. The parent hydrocarbon 1 that was obtained as a side product in the Elbs pyrolysis of (2‐methyl‐1‐naphthyl)‐1′‐naphthylmethanone (10) was oxidized to 3‐(2‐formylphenyl)‐3‐phenanthrenecarboxaldehyde (3). Treatment of the dialdehyde with tris(dimethylamino)phosphine gave 4b,5a‐dihydrodibenz[3,4:5,6]anthra[1,2‐b]oxirene (4). Reaction of the oxirane with sodium azide followed by triethyl phosphite cyclization of the mixture of trans azido‐alcohols so formed, yielded mainly 4b,5a‐dihydrodibenz[3,4:5,6]anthra[1,2‐b]azirine (5).
Syntheses and reactions of [1,3,4]thiadiazolo[3,2‐a]pyrimidinone derivatives
Authors: Tsuji Tadakazu 
Published: March 2009

Abstract5‐Imino‐6H‐7‐one, 7‐amino‐5‐one and 5‐isocyano‐7‐one derivatives of [1,3,4]thiadiazolo‐ and ‐[1,3]thiazolo‐[3,2‐a]pyrimidines were synthesized. 5‐Isocyano‐7‐one derivatives were obtained by the reaction of the corresponding 5‐imino‐6H‐7‐ones with the Vilsmeier reagent in one step.
Synthesis of pyrimidine derivatives using N‐bis(methylthio)methylenecyanamide
Authors: Tominaga Yoshinori , Ohno Syuichirou , Kohra Shinya , Fujito Hiroshi , Mazurae Hisako 
Published: March 2009

AbstractN‐Bis(methylthio)methylenecyanamide (1) was allowed to react with active methylene compounds (methyl cyanoacetate, dimethyl malonate, ethyl acetoacetate, ethyl phenylacetate) in the presence of potassium carbonate or potassium hydroxide in dimethyl sulfoxide followed by the treatment using appropriate a base or an acid to give the corresponding 6‐methylthiouracil derivatives in 15–80% yields.These uracil derivatives are found to be useful intermediates for the synthesis of 6‐aminouracils and fused pyrimidine derivatives.
Synthesis and antibacterial activities of novel dihydrooxazine and dihydrothiazine ring‐fused tricyclic quinolonecarboxylic acids: 9‐Fluoro‐3‐methylene‐10‐(4‐methylpiperazin‐1‐yl)‐7‐oxo‐2,3‐dihydro‐7h‐pyrido[1,2,3‐de][1,4]benzoxazine‐6‐carboxylic acid and its 1‐thia congener
Authors: Okada Tetsuo , Tsuji Teruji , Tsushima Tadahiko , Yoshida Tadashi , Matsuura Shinzo 
Published: March 2009

AbstractA new synthetic method was developed to obtain two novel tricyclic quinolonecarboxylic acids, 9‐fluoro‐3‐methylene‐10‐(4‐methylpiperazin‐1‐yl)‐7‐oxo‐2,3‐dihydro‐7H‐pyrido[1,2,3‐de][1,4]benzoxazine‐6‐carboxylic acid (2) and its 1‐thia congener 3. The method involves the key intermediate of an oxetane derivative and its cleavage with acids. Evaluation of the antibacterial activities showed that 2 and 3 are excellent against both Gram‐positive and Gram‐negative organisms in vitro, being comparable to or only slightly less effective than Ofloxacin. In experimental systemic infections in mice, compound 2 showed distinctly higher activity than Ofloxacin, especially against infection caused by Escherichia coli.
Pyrazoles. 6. Synthesis of novel heteroaryl 4‐pyrazolyl ketones
Authors: Hahn Marianne , Heinisch Gottfried , Holzer Wolfgang , Schwarz Helga 
Published: March 2009

AbstractThe preparation of a variety of novel heteroaromatic analogues of benzophenone 2–11 characterized by a 4‐pyrazolyl moiety and a thienyl‐, azinyl‐ or diazinyl‐system starting from 1,4‐dilithiopyrazole is reported.
Alkylation of cycloalkano[B]indoles via indolylmagnesium salts: Synthesis of 3h‐indoles and oxidative rearrangement to spiro[cycloalkane‐1,2′‐indolin]‐3′‐ones
Authors: Rodriguez JosÈ‐Gonzalo , Andrès Angel San 
Published: March 2009

AbstractAlkylation of cycloalkano[b]indolylmagnesium iodide with alkyl halides has been analyzed to prepare cycloalkano‐3H‐indoles, methyl and N,N‐dimethylpropyl derivatives. Spiro[cycloalkane‐1,2′‐indolin‐3′‐one] derivatives appear as secondary products in this reaction. Selectivity and optimization of the reaction has been determined and a mechanism for the formation of the spiro derivative is proposed.
A convenient synthesis of ethyl 2‐(4‐nitrophenyl)‐3,4‐disubstituted and c‐fused thiophene‐5‐carboxylates
Authors: Rangnekar D. W. , Mavlankar S. V. 
Published: March 2009

AbstractA convenient one step synthesis of the hitherto unknown ethyl 2‐(4‐nitrophenyl)‐3,4‐disubstituted and c‐fused thiophene‐5‐carboxylates was achieved by the condensation of ethyl 4‐nitrobenzylthioacetate with a variety of 1,2‐dicarbonyl compounds using sodium ethoxide in refluxing ethanol.
Synthesis of 3‐disubstituted 3H‐4,1,2‐benzothiadiazines and 3‐disubstituted 3H‐4,1,2‐benzothiadiazine 4,4‐dioxides
Authors: Balbi A. , Mazzei M. , Sottofattori E. 
Published: March 2009

Abstract3H‐4,1,2‐Benzothiadiazines 8 and 9 have been prepared by cyclization of the key intermediates 6 and 7. The diazotisation of 2‐aminophenylthio and 2‐aminophenylsulfone derivatives could represent a new convenient synthetic way to obtain 4,1,2‐benzothiadiazines.
Synthesis of pyrazole derivatives as potential bioisosteres of thromboxane‐synthetase inhibitors
Authors: Barreiro Eliezer J. , Freitas Antonio C. C. 
Published: March 2009

AbstractA series of ω‐carboalkenyl pyrazole derivatives have been synthesized as potential thromboxane‐synthetase inhibitors considering the close bioisosteric relationship between the pyrazole ring and other heteroaromatic carboalkenyl compounds exhibiting inhibitory activity. (E)‐7‐(1‐Phenylpyrazol‐4‐yl)hept‐2‐enoic acid (4b) were prepared in 28% overall yield from its minor bis‐homologue, (E)‐5‐(1‐phenylpyrazol‐4‐yl)pent‐2‐enoic acid (4a), obtained from 4‐formyl‐1‐phenylpyrazole (6) in 17% overall yield. Compounds 4a, 4b, 7, 8 and 13 were screened for their ability to inhibit the in vitro rabbit blood platelet aggregation induced by collagen using the Born test. Among the active compounds 4a exhibited an important inhibition at 1 μM concentration.
Intramolecular sulphonamidomethylation. Part II. Fused heterocycles from 2‐phenylethanesulphonamides
Authors: Zinczuk Juan , Sorokin Isidoro H. , Orazi Orfeo O. , Corral Renée A. 
Published: March 2009

Abstract1,2,4,5‐Tetrahydro‐3,2‐benzothiazepine 3,3‐dioxides 2, with a variety of substituents on the nitrogen atom, can be easily obtained by the title reaction. The isomeric compounds 4–6 are also formed from sulphonamides bearing an N‐aralkyl group with a chain of two or more carbon atoms. Activation of the ring closure‐position or deactivation of the aromatic ring in the substituent can direct the reaction to give compounds 2. Cyclization results are influenced by the size of the new heterocycle ring and by the predominant formation of derivatives with the SO2 group outside the ring.
Synthesis of 7‐ and 5,7‐substituted‐6‐fluoro‐2‐methyl‐1,2,3,4‐tetrahydroquinolines: Convenient precursors of quinolone antibacterial agents
Authors: Bouyssou Pascal , Le Goff Corinne , Chenault Jacques 
Published: March 2009

AbstractAn original procedure to obtain substitution at the 7 or 5, 7 positions on 6‐halogenated tetrahydroquinaldines is described. The title products are a new class of precursors of quinolone antibacterial agents.
Facile synthesis of 2‐[1‐(alkylthio)alkyl]pyridines and phenyl‐substituted derivatives
Authors: Kiselyov Alexander S. , Strekowski Lucjan , Semenov Victor V. 
Published: March 2009

AbstractThe title compounds 5 are produced in the reaction of N‐fluoropyridinium tetrafluoroborate (1) with sulfides 2. The proposed mechanism involves single‐electron transfer from 2 to 1 followed by transformations of the resultant radical intermediates.
On triazoles. XXIX. The reaction of triazolyl thiohydrazides with isocyanates and isothiocyanates
Authors: Reiter József , Barkóczy József 
Published: March 2009

AbstractDifferent N‐methylsubstituted, N'‐methylsubstituted and N,N'‐unsubstituted triazol‐1‐ylcarbothiohydrazides were reacted with isocyanates and isothiocyanates to yield the corresponding carbamoyl and thiocarbamoyl derivatives 4. The thiocarbamoyl derivatives could be cyclised by heating in dimethylformamide or 10% sodium hydroxide solution, reacting them with dicyclohexylcarbodiimide or thier alkylation to the corresponding 1,3,4‐thiadiazoles 12 and 16, and derivatives 5 formed by splitting the triazole moiety. Cleaved derivatives 9 and 11 were also formed in the reaction of thiocarbamoyl derivatives 4 with carbon disulfide in the absence or presence of methyl iodide, respectively. Spectroscopic evidence is given for the structure of products obtained.
A convenient synthesis of 3,4‐dihydro‐2‐methyl‐3‐oxo‐2H‐1,4‐benzoxazine‐2‐carboxylic acids and 3,4‐dihydro‐2‐methyl‐3‐oxo‐2H‐pyrido[3,2‐b]‐1, 4‐oxazine‐2‐carboxylic acid
Authors: Suhadolc Elizabeta , Urleb UroŠ , Žbontar Urša , Kikelj Danijel 
Published: March 2009

AbstractA convenient one pot synthesis of ethyl 3,4‐dihydro‐2‐methyl‐3‐oxo‐2H‐1,4‐benzoxazine‐2‐carboxylates and 3,4‐dihydro‐2‐methyl‐3‐oxo‐2H‐pyrido[3,2‐b]‐1,4‐oxazine‐2‐carboxylates and their conversion into the respective carboxylic acids are described.
Synthesis of imidazo[4,5‐c]quinolin‐4(5H)‐one via radical cyclization
Authors: Suzuki Fumio , Kuroda Takeshi 
Published: March 2009

AbstractThe tributyltin radical‐induced cyclization of N‐(2‐bromophenyl)‐Nbutyl‐1H‐1‐methylimidazole‐4‐carbox‐amide 3 gave 5‐butyl‐3‐methyl‐3H‐imidazo[4,5‐c]quinolin‐4(5H)‐one 5 via [1,2]‐acyl rearrangement.
The synthesis of substituted 1,5‐benzodiazepines
Authors: Cohen Victor I. , Jin Biyun , Reba Richard C. 
Published: March 2009

AbstractThe synthesis of some substituted 1,5‐benzodiazepines are described. The route is based on the reaction between 1,4‐phenylenediamine and its derivative with crotonic acid or methacrilic acid.
Reissert compound studies LXVI. Regioselective synthesis of pyridine reissert analogs
Authors: Duarte F. F. , Popp F. D. , Holder A. J. 
Published: March 2009

AbstractThe reaction of ethyl chloroformate and pyridine with diethylaluminum cyanide as the cyanide source gave the Reissert analog, 1‐ethoxycarbonyl‐4‐cyano‐1,4‐dihydropyridine and not the expected 1,2‐dihydro regio isomer. Under the same conditions, 3‐bromopyridine also directly gave the corresponding 1,4‐dihydro Reissert analog. Reinvestigation of trimethylsilylcyanide, as the cyanide source, resulted in the observation that both regio isomers are formed and the ratio of these isomers are affected by both solvent polarity and by copper(I) iodide.
Acetylene chemistry. Part 28. New C‐2 substituted furo[2,3‐b]quinolines via Pd‐catalyzed reaction
Authors: Reisch Johannes , Nordhaus Petra , Pflug Thomas 
Published: March 2009

AbstractFour new C‐2 substituted furo[2,3‐b]quinolines have been synthesized via Pd‐catalyzed reaction. The present study was to provide furo[2,3‐b]quinolines for biological studies on the influence of the side chain length and its polarity of the biological activity particularly against phytopathogenic bacteria and fungi.
Synthesis and characterization of the new 22‐π aromatic furan‐containing macrocycle, “ozaphyrin”
Authors: Miller Douglas C. , Johnson Martin R. , Becker John J. , Ibers James A. 
Published: March 2009

AbstractThe new 22‐π, aromatic “pentaplanar” macrocycle, ozaphyrin (6), has been synthesized by a McMurry coupling of 5,5′‐diformyl‐4,4′‐dipropyl‐2,2′‐bipyrrole (1) with 2,5‐bis(5‐formyl‐4‐propyl‐2‐pyrrolyl)furan (5). This synthetic pathway to ozaphyrin and its characterization by 1H nmr spectroscopy, uv‐visible spectroscopy, cyclic voltammetry, and X‐ray crystallography are described. The structure consists of layers of planar, staggered macrocycles stacked perpendicular to the α‐axis. Ozaphyrin crystallizes with four formula units in the monoclinic space group C52h‐P21/n in a cell of dimensions a = 10.481(7) Å, b = 17.353(17) Å, c = 18.726(12) Å, and β = 102.84(5)° (108 K). The structure has been refined on F2 (5171 unique reflections, 411 variables) to Rw(Fo2) = 0.165. The conventional agreement index R(F) is 0.074 for the 3289 reflections have Fo2>2o(Fo2).
Synthesis and photophysical properties of fluorescent 2,5‐dibenzoxazolylphenols and related compounds with excited state proton‐transfer
Authors: Kauffman Joel M. , Bajwa Gurdip S. 
Published: March 2009

AbstractA series of new 2,5‐dibenzoxazolylphenols and related compounds was prepared by condensation of hydroxy‐ and methanesulfonamidoterephthalic acids with 2‐aminophenols. These displayed excited state intramolecular proton‐transfer fluorescence at room temperature and above with quantum yields as high as 0.48 and emission peaks of 492‐517 nm. The methanesulfonamido group was found about as effective a proton donor as the phenolic hydroxyl group. Incorporation of substituents onto the benzoxazole moieties increased solubility of the fluors in hydrocarbon solvents in some cases, but reduced quantum yields. These fluors are of interest as wavelength shifters in a scintillating detecting medium for ionizing radiation.
Assignment of the Phosphorus, Proton and Carbon‐NMR Spectra of [(Tetrahydro‐2‐hydroxy‐5,5‐dimethyl‐4H‐1,4,2‐oxazaphosphorin‐4‐yl)methyl] phosphonic acid P‐Oxide
Authors: Dhawan Balram , Redmore Derek , Boyd Walter A. 
Published: March 2009

AbstractThe 1H and 13C nmr signals of the methylene groups directly linked to the phosphorus atoms, namely P(2)‐C(3)H2 and P(8)‐C(7)H2 in 1a were assigned with the help of hetronuclear decoupling experiments and HETCOR spectrum.
A new route to pyridine derivatives by the reaction of tris(isopropylthio)cyclopropenylium perchlorate with α‐lithiated isocyanides
Authors: Kojima Hideo , Yamamoto Kazuhiko , Kinoshita Yasuo , Inoue Hiroo 
Published: March 2009

AbstractThe reaction of tris(isopropylthio)cyclopropenylium perchlorate (1) with α‐lithiated tosylmethyl, benzyl and benzoylmethyl isocyanides 2a‐c in dry tetrahydrofuran gave the pyridine derivatives 3a‐c respectively.
Synthesis of 1‐aryl‐5‐chloro‐3‐(phenylsulfonyl)pyrazol‐4‐ols from 1,1‐dichloro‐3‐phenylsulfonyl‐2‐propanone
Authors: Takahashi Masahiko , Zheng Min , Oshida Takeshi , Narahara Kiyosi 
Published: March 2009

Abstract1,1‐Dichloro‐3‐phenylsulfonyl‐2‐propanone was treated with arenediazonium chlorides to give 1‐arylhydrazono‐3,3‐dichloro‐1‐phenylsulfonyl‐2‐propanones, which were cyclized to 1‐aryl‐5‐chloro‐3‐(phenylsulfonyl)pyrazol‐4‐ols on treatmemt with base.
Coumarin as dipolarophile towards 3,5‐dichloro‐2,4,6‐trimethylbenzonitrile oxide
Authors: Baldoli Clara , Gioffreda Fabio , Zecchi Gaetano 
Published: March 2009

AbstractThe reaction of coumarin with the title nitrile oxide gives a single regioisomer in high yield. This result is compared with the dipolarophilic behavior of cinnamic acid esters.
New general synthesis of tetrahydro‐1,2,4,5‐tetrazin‐3(2H)‐one derivatives and stable 3,4‐dihydro‐3‐oxo‐1,2,4,5‐tetrazin‐1(2H)‐yl radical derivatives
Authors: Milcent René , Barbier GÉO , Capelle Sylvie , Catteau Jean‐Pierre 
Published: March 2009

AbstractReactions of 2‐chloroformylhydrazones of aromatic aldehydes or ketones 2 with various hydrazines were converted to monocarbonohydrazone derivatives 3 or 5 and/or tetrahydro‐1,2,4,5‐tetrazin‐3(2H)‐one derivatives 6, 7. By oxidation with lead dioxide, compounds 6 were transformed into stable 3,4‐dihydro‐3‐oxo‐1,2,4,5‐tetrazin‐1(2H)‐yl radical derivatives 8.
Unusual ring transformations: Reaction of phenyl 7‐fluoro‐4‐chromone‐3‐sulfonate with methyl 3‐oxo‐pentanoate in the presence of ammonium acetate
Authors: Löwe Werner , Schott Susan 
Published: March 2009

AbstractThe novel benzoxathiinopyridines 4 and 5, the hitherto unknown dibenzopyrone 6 and the heterocyclic enaminone 7 have been synthesized by ring transformations of phenyl 7‐fluoro‐4‐chromone‐3‐sulfonate (1) with methyl 3‐oxopentanoate (2) in the presence of ammonium acetate (3). The structures of 4–7 were determinated by spectroscopic methods and the reaction pathways of formation for these compounds are discussed.
3‐Amino‐2‐quinoxalinecarbonitrile. New fused quinoxalines with potential cytotoxic activity
Authors: Monge A. , Palop J. A. , Piñol A. , Martínez‐Crespo F. J. , Narro S. , González M. , Sáinz Y. , De Ceráin A. López , Hamilton E. , Barker A. J. 
Published: March 2009

AbstractStarting with 3‐amino‐2‐quinoxalinecarbonitrile 1,4‐dioxide 1, a new series of quinoxaline derivatives was prepared through chemical modifications of the 2‐cyano and 3‐amino groups. Nitration of 3‐amino‐2‐quin‐oxalinecarbonitrile 3 afforded the 7‐nitro derivative 6. Diazotation of 3 gave the 3‐chloro compound 9. 2,3‐Quinoxalinedicarbonitrile 14 was obtained from 9. Pyridazino[4,5‐b]quinoxalines 15 and 16 were prepared by condensing 14 with hydrazine hydrate. A triazolo[4,5‐b]quinoxaline 18, a isothiazolo[4,5‐b]quinoxaline 20 and two pyrazolo[3,4‐b]quinoxalines 21 and 22 were identified. Compounds were tested as cytotoxic agents both in oxic and in hypoxic cells.
Synthesis of 2,3,5‐trisubstituted furans by the acid‐catalyzed decomposition of 1,2‐dioxan‐3‐ols
Authors: Qian Chang‐Yi , Hirose Jun‐Ichi , Nishino Hiroshi , Kurosawa Kazu 
Published: March 2009

AbstractThirteen new 2,3,5‐trisubstituted furans were prepared by the acid‐catalyzed decomposition of 6,6‐di‐substituted 1,2‐dioxan‐3‐ols in 57‐93% yields. The reaction could be accounted for as the consequence of an oxygen‐oxygen bond cleavage by acid and the migration of a phenyl group at the C‐6 position followed by cyclization and elimination of a phenol. The migratory aptitude was in the order of 4‐MeOC6H4‐ > 4‐MeC6H4‐ > Ph‐ = 4‐FC6H4‐ > 4‐ClC6H4‐ = 4‐BrC6H4‐ that was found from the competitive phenyl migration in the reaction of 1,2‐dioxan‐3‐ols bearing two different substituents at the C‐6 position.
New regional isomers of 1‐methyl‐5‐(trifluoromethyl)pyrazoles
Authors: Chupp John P. 
Published: March 2009

AbstractUtilizing the recently reported compound, 1‐methyl‐5‐(trifluoromethyl)‐2,3,4,5‐tetrahydropyrazol‐3‐one, 4, a series of regional isomers of 1‐methyl‐5‐(trifluoromethyl)‐3‐chloropyrazole, newly substituted in the 4‐position were prepared by original syntheses. Chief among them was the new regional 4‐hydroxy isomer, 3a, a linkage reagent valuable for preparing new SAR candidates in the bio‐active pyrazole phenyl ether series.
An improved procedure for the preparation of 2‐amino‐8‐alkylpyrido‐[2,3‐d]pyrimidin‐4(3H)‐ones (8‐alkyl‐N5‐deazapterins)
Authors: Ivery Michael T. G. , Gready Jill E. 
Published: March 2009

AbstractWe report an improved procedure for the preparation of 8‐alkyl‐N5‐deazapterins which allows clean preparation of all ring‐methyl substituted compounds, including 5‐ and 7‐methyl substituted compounds. The procedure was also successfully applied to the preparation of N5‐deazapterins with improved yield over previous reports. The uv/visible and pKa data confirm the predicted increased basicity of 8‐alkyl‐N5‐deazapterins compared with the N5‐deazapterin parents, and indicate that N5‐deazapterins protonate on N8 and 8‐alkyl‐N5‐deazapterins protonate on N3.
Reductive cyclization of 1‐(2‐nitroaryl)isoquinoline derivatives
Authors: Stanley Alan L. , Stanforth Stephen P. 
Published: March 2009

AbstractIsoquinoline derivatives 3b and 3c were prepared and their triethyl phosphite mediated reductive cyclization reactions investigated. Only the indazolo[3,2‐a]isoquinolines 4b and 4c were formed.