bluuebunny/crossref_metadata_2025_split huggingface dataset:
Picrylamino‐substituted heterocycles. II. Furazans
Authors: Coburn Michael D. 
Published: April 2009

AbstractThis paper describes the synthesis of the various picrylamino‐ and nitro‐substituted furazans and bifurazanyls. Except for 3,4‐bis(picrylamino)furazan, which was obtained by nitrating 3,4‐dianilinofurazan, the picrylaminofurazans were prepared by condensing the appropriate amino‐furazan with picryl fluoride in the presence of triethylamine. The various aminofurazans were oxidized with peroxytrifluoroacetic acid to the corresponding nitro derivatives.
Tautomer chemistry of thiazolidines. 1‐Thia‐4‐azaspiro[4,5] decanes
Authors: Stacy Gardner W. , Strong Philip L. 
Published: April 2009

AbstractThe thiazolidine, 1‐thia‐4‐azaspiro[4,5] decane (Ia), which is derived from cyclohexanone and 2‐aminoethanethiol (X), forms a thiazolidone (VIII) with mercaptoacetic acid more slowly and in lower yield than with 2‐phenylthiazolidine, a case reported previously. A thiazolidine which is related to a non‐conjugate chain tautomer such as Ic, might be expected to behave in this way. Alkylation, as another possible example of tautomer chemistry, was studied, and N‐, S‐, and C‐alkylation were all observed under varying circumstances. Thus, thiazolidine la undergoes alkylation with methyl iodide in ethanol to form the N‐methylthiazolidine (IIa), and in sodium‐liquid ammonia to give the S‐methyl derivative (III). In the latter case, alkylation occurs with reductive cleavage. Although no trace of other tautomer derivatives (IV, V) was to be found in the methyl iodide alkylation, I with acrylonitrile did in fact give C‐alkylation. An analytically pure mixture of tautomers was obtained, from which 2‐oxocyclohexanepropionitrile (VI) was isolated on hydrolysis. In a manner similar to the formation of III, IIa was S‐alkylated by treatment with sodium‐liquid ammonia followed by benzyl chloride to give a saturated product (XVII). Although such a process might be identified with a chain tautomer (IIb), the evidence is to the contrary, since the intermediate (XIV), which might be involved in such a process, fails to undergo a similar reduction with sodium‐liquid ammonia. A greatly improved procedure for the preparation of thiazolidine (XI, 86% yield) is also reported.
Synthesis of possible metabolites of chlorpromazine. II. 3‐, 8‐ and 9‐hydroxychlorpromazine
Authors: Nodiff Edward A. , Oda Noriichi , Hayazaki Takanori , Ina Shuichiro , Ito Toshiyuki , Nishibe Sansei , Ueda Taisei , Suzuki Kenji , Hausman Martin , Manian Albert A. 
Published: April 2009

AbstractThe title compounds have been prepared as analytical standards for the identification of chlorpromazine metabolites in biological materials. Unequivocal structural proof of key compounds was accomplished by using at least two unrelated syntheses for each one. Resistance of some phenothiazines to preparation via classic Smiles rearrangement is discussed. More examples are offered of halogen‐induced Smiles rearrangement. A rare example of phenothiazine polymorphism is presented.
A direct, stereoselective synthesis of optically active conhydrines
Authors: Fodor Gabor , Bauerschmidt Eberhard 
Published: April 2009

Abstract2‐Pyridylethylcarbinol (I) has been resolved and the antipodes hydrogenated as free bases. The (+) form gave (+) conhydrine (II) while the (‐) form afforded the levorotatory base stereoselectively with minor contamination of the other epimer. Hydrogenation of racemic I as well as of 2‐pyridyl ethyl ketone in acid solution led formerly to the mixture of both racemates.
Reaction of certain isocyanates with azomethines. Evidence for a new heterocyclic adduct
Authors: Chupp John P. , Landwehr Helen K. 
Published: April 2009

AbstractThe preparation of triazinone (I) from certain isocyanates and N‐alkyl azomethines was found to proceed easily without catalyst, particularly in refluxing chlorobenzene. The physical and chemical properties, including n.m.r. spectra of the oily triazinones, are contrasted with the newly discovered solid adducts arising from low temperature reaction of azomethine and chlorophenyl isocyanates. From stoichiometry of the reaction, elemental analysis, molecular weight of the products, and spectral analyses, the new materials (II) were found to incorporate two isocyanate and three azomethine moieties in their molecular make‐up. The relative merits are considered for assigning II a molecular structure arising from a complex between a four and six‐membered ring (III, IV) versus a ten‐membered ring system (V, VI, VIa).
Azasteroids. v. approaches to the 14,16‐diazasteroidal ring system
Authors: Katz Lawrence E. , Popp Frank D. 
Published: April 2009

AbstractMaking use of Reissert compound II and Reissert compound analogue VI, benzo [f]quinoline has been converted into the 14,16‐diazasteroidal ring system. A number of reactions in this ring system are discussed.
The synthesis and some reactions of 2,3‐substituted 1‐phenylbenzo[f]quinoline
Authors: Chan Tze‐Lock , Hamer Jan 
Published: April 2009

AbstractA series of 2,3‐substituted 1‐phenylbenzo[f]quinolines was synthesized by the Friedlander condensation of 1‐benzoyl‐2‐naphthylamine with β‐keto esters. Some chemical transformations of these compounds and the preparation of 13H‐benzo[f]indeno[2,1‐c]quinoline‐13‐one and its 9‐methyl derivative are described.
The reaction of 2‐(ω‐chloroalkyl)benzimidazoles with thiourea. Studies on heterocyclic compounds. I
Authors: Ogura H. , Itoh T. , Tajika Y. 
Published: April 2009

AbstractBy reaction of the appropriate 2‐(ω‐chloroalkyl)benzimidazoles with thiourea, 2‐(α‐mercaptoalkyl)benzimidazoles (IV) have been prepared. The attempted preparation of 2‐(β‐ and γ‐mercaptoalkyl)benzimidazoles failed. β‐Elimination was observed by alkaline treatment of S‐[2‐(2‐benzimidazolyl)‐propyl]isothiuronium chloride (VII), whereas 2‐(γ‐chlorobutyl)benzimidazoles did not give an isothiuronium chloride.
Thiophene series. Note IX . The absence of secondary steric effects in nucleophilic substitutions of thiophene derivatives: Kinetics of the reactions of 2‐bromo‐3,5‐dinitrothiophene and 2‐bromo‐3,5‐dinitro‐4‐methylthiophene with piperidine
Authors: Spinelli Domenico , Guanti Giuseppe , Dell'Erba Carlo 
Published: April 2009

AbstractThe kinetics of the reactions of piperidine with 2‐bromo‐3,5‐dinitrothiophcne (IV) and 2‐bromo‐3,5‐dinitro‐4‐methylthiophene (III) have been measured in methanol, ethanol and benzene.Molecular model predictions were confirmed when the kinetic results (kIV/kIII ≅ 2) demonstrated, for the first time, the absence of secondary steric effects for nucleophilic substitutions in thiophene compounds.
Crystal and molecular structure of 6‐(p‐bromobenzoyl)‐6‐azabicyclo[3.1.0]hexane
Authors: Zacharis H. M. , Trefonas L. M. 
Published: April 2009

AbstractThe molecular structure of 6‐(p‐bromobenzoyl)‐6‐azabicyclo[3.1.0]hexane has been determined by a single crystal, three‐dimensional x‐ray study. The compound crystallizes in the monoclinic space group (P) with four molecules in a unit cell of dimensions a = 8.83, b = 10.15, c = 12.63 ± 0.02Å and β = 94°55′ ± 5′. The aziridine ring is eis fused to the cyclopentane ring with the two rings together in a boat conformation. The fusion angle of the two rings is 110.8°. The aziridine ring has all angles of 60 ±1° and all bond distances of 1.48 ± 0.03Å. The cyclopentane ring has alternately long (1.61 ± 0.04Å) and short (1.52 ± 0.02Å) distances. Non‐fusion angles in the cyclopentane ring are 106.0 ± 0.5°. Other molecular parameters are as anticipated. The 844 independent reflections obtained were refined to a final value of R = 0.116 using full‐matrix least squares techniques.
1‐Aryl‐4,6‐diamino‐1,2‐dihydro‐s‐triazines. Contrasting effects on intestinal helminths, bacteria, and dihydrofolic reductase
Authors: Capps David B. , Bird Orson D. , Elslager Edward F. , Gavrilis Zoe B. , Roush Jane A. , Thompson Paul E. , Vaitkus John W. 
Published: April 2009

AbstractThe preparation of a variety of novel 1‐aryl‐4,6‐diamino‐1,2‐dihydro‐s‐triazines is described. These compounds exhibit an array of contrasting effects on intestinal helminths, bacteria, and dihydrofolic reductase. It is concluded that potent anthelmintic activity among the dihydro‐triazines is not dependent solely on the bulky‐substituent hypothesis advanced by other investigators, and indeed cannot reliably be predicted on this basis.
Pyridazines. IV. The synthesis and some reactions of acetylpyridazines
Authors: Nakagome Takenari , Castle Raymond N. 
Published: April 2009

AbstractTwo 3‐acetylpyridazines have been prepared. N‐Oxidation of 3‐acetylpyridazine (6) gave only 3‐acetylpyridazine 1‐oxide (7). During the N‐oxidation of 3‐acetyl‐6‐methoxypyridazine (10), three primary products, namely, 3‐acetyl‐6‐methoxypyridazine 1‐oxide (12), 3‐acetyl‐6‐methoxy‐pyridazine 2‐oxide (13), 3‐acetylpyridazin‐6‐one (14) and an artifact, 3‐methoxypyridazine 1‐oxide (15) were obtained. Furthermore, it has been shown that 3‐methoxypyridazine 1‐oxide (15) can be obtained in quantitative yield by treatment of 3‐acetyl‐6‐methoxypyridazine 2‐oxide (13) with dilute sodium hydroxide solution at room temperature. This represents a novel deacylation reaction. Nitration of 3‐acetylpyridazine 1‐oxide, (7) gave 3,4‐bis(3′‐pyridazinoyl)furoxan 1′,1′‐dioxide (19) rather than a simple nitration product. 3‐Acetyl‐pyridazine (6) and 3‐acetyl‐6‐methoxypyridazine (10) also gave furoxans (22 and 23) upon nitration.
Aromaticity in heterocyclic systems V. Bromination studies of certain purines, pyrrolo[3,2‐d]pyrimidines and pyrazolo[4,3‐d]pyrimidines
Authors: Cassidy Frederick , Olsen Richard K. , Robins Roland K. 
Published: April 2009

AbstractThe bromination of certain selected purines, pyrrolo[3,2‐d]pyrimidines and pyrazolo[4,3‐d]‐pyrimidines has been studied and the reactivity of these systems compared. Displacement of a carboxyl group by bromine was noted in the case of 6‐carboxypyrrolo[3,2‐d]‐2,4‐pyrimidinedione. In contrast to xanthine, 2,6‐diethoxypurine readily brominated at position 8. Pyrazolo‐[4,3‐d]‐7‐pyrimidone was readily brominated at position 3.
Heterocyclic tautomerisms. III. An investigation of the 2‐arylbenzothiazoline‐2‐(benzylideneamino)thiophenol tautomerism. Part 3
Authors: Goetz Frederick J. 
Published: April 2009

AbstractThe electronic spectra of various, substituted 2‐arylbenzothiazoline (1)‐2‐(benzylideneamino)‐thiophenol (II) tautomers were studied in order to determine what species were present in ethanol solution. In every case examined the absorption spectra closely resembled those of the correspondingly substituted 3‐methyl‐2‐arylbenzothiazolines (III) and differed markedly from those of corresponding 2‐(benzylideneamino)phenyl methyl sulfides (IV). These results indicate that, under the conditions examined, the 2‐arylbenzothiazoline tautomer (I) predominates. Infrared spectra determined or solid samples of series I‐II, III and IV were entirely in accord with structure I.
The synthesis of 5,10‐dihydro‐ and 2,3,5,10‐tetrahydrothiazolo‐[3,2‐b] [2,4]benzodiazepines, 1,2,3,4,7,12‐hexahydrobenzothiazolo‐[3,2‐b] [2,4] benzodiazepine, and 9,14‐dihydro‐6H‐[1]benzothiopyrano‐[4′,3′:4,5]thiazolo[3,2‐b] [2,4] benzodiazepine via 1,2,4,5‐Tetrahydro‐3H‐2,4‐benzodiazepine‐3‐thione
Authors: Elslager Edward F. , Worth Donald F. , Haley Neil F. , Perricone S. C. 
Published: April 2009

AbstractCatalytic reductive scission of phthalazine (II) utilizing a two‐stage palladium‐Raney nickel procedure afforded o‐xylene‐α,α′‐diamine (III) in 97% yield. Treatment of III with carbon disulfide gave [o‐(aminomethyl)benzyl]dithiocarbamic acid (IV), which upon thermal cyclization furnished 1,2,4,5‐tetrahydro‐3H‐2,4‐benzodiazepine‐3‐thione (V). Reaction of V with 1,2‐dibromoethane, chloro‐2‐propanone, ethyl 2‐chloroacetoacetate, ethyl chloroacetate, and ethyl 2‐bromohexanoate gave 2,3,5,10‐tetrahydrothiazolo[3,2‐b][2,4]benzodiazepine (VII) and substituted 5,10‐dihydrothiazolo[3,2‐b][2,4]benzodiazepines (Villa and b, IX, and X), respectively. Condensation of V with 2‐chlorocyclohexanone and 3‐bromothiochroman‐4‐one afforded 1,2,3,4,7,12‐hexahydrobenzothiazolo[3,2‐b][2,4]benzodiazepine (XII) and 9,14‐dihydro‐6H‐[1]benzothiopyrano[4′,3′:4,5]thiazolo[3,2‐b][2,4]benzodiazepine(XIll). None of the compounds possessed appreciable biological activity.
Flavinyl peptides. I. Synthesis of flavinyl‐aromatic amino acids
Authors: Föry Werner , Mackenzie Robert E. , Mccormick Donald B. 
Published: April 2009

AbstractThe syntheses of flavinyl peptides, in which L‐tryptophan, L‐tyrosine, or L‐phenylalanine are attached via peptide linkage to the isoalloxazine system with ω‐carboxyalkyl groups in position 3 or 10, are described. Lumiflavin was carboxymethylated by known methods to yield N‐3‐carboxymethyllumiflavin. Oxidation of 10‐ω‐hydroxyhexyl‐, 10‐ω‐hydroxypentyl‐, 10‐ω‐hydroxybutyl‐, and 10‐formylmethylflavins gave the corresponding 10‐ω‐carboxyalkylflavins. The 10‐ω‐carboxyethylflavin was obtained by condensation of 2‐amino‐4,5‐dimethyl‐N‐ω‐carboxyethylaniline with alloxan. Activations of the carboxyl group of the flavins were achieved with N,N′‐carbonyldiimidazole and p‐nitrophenyltrifluoroacetate to form the corresponding acyl imidazoles and p‐nitrophenyl esters. 10‐Carboxymethylflavin was hydrogenated to form 10‐carboxymethyldihydroflavin and activated by carbodiimide. Reaction of the carboxy‐activated flavins with the appropriate amino acid methyl esters, followed by air oxidation in the case of dihydroflavin, gave the corresponding flavinyl peptides.Interaction of the flavin with aromatic amino acids results in a broadening of the visible flavin absorption towards the green, without the appearance of discrete new maxima, and in quenching of the flavin fluorescence. The fluorescence efficiency increases with increasing numbers of methylene groups in the flavin side chain. The nonlinear dependency of fluorescence quenching versus number of methylene groups indicates that different types of intramolecular interactions are involved.
NMR proof of the structure of 4‐aminoquinolines and pyridines
Authors: Craig John C. , Pearson D. E. 
Published: April 2009

AbstractNmr spectra of a number of 4‐N‐alkylaminoquinolines and 4‐N‐alkylaminopyridines show coupling between hydrogen of the amino group and α‐hydrogen on the alkyl group. No such coupling would be observed if the hydrogen were on heterocyclic nitrogen. Other nmr characteristics in the benzenoid region suggest that all simple 4‐aminoquinolines and 4‐aminopyridines have the amino structure.
Preparation and ultraviolet absorption spectra of the isomeric naphthobenzothiophenes and naphthobenzofurans
Authors: Campaigne E. , Osborn S. W. 
Published: April 2009

AbstractNaphtho[2,1‐b]benzothiophene has been synthesized unequivocally by the ring closure of 2‐phenylmercapto‐1‐tetralone, followed by dehydrogenation of the resulting dihydro derivative. The other isomeric naphthobenzothiophenes have been prepared by modifications of known methods and their ultraviolet absorption spectra have been compared.Condensation of α‐naphthol with 2‐chlorocyclohexanone leads to 7,8,9,10‐tetrahydronaphtho‐[1,2‐‐6]benzofuran, which can be readily dehydrogenated with selenium to naphtho[1,2‐b]‐benzofuran. The ultraviolet spectra of the naphthobenzofurans are reported, and compared to their sulfur analogs.
A mechanistic study of the synthesis of meso‐tetraphenylporphin
Authors: Adler Alan D. , Sklar Larry , Longo Frederick R. , Finarelli John D. , Finarelli Margaret G. 
Published: April 2009

AbstractIn continuation of an earlier preliminary study, some further physical and synthetic studies on the homogenous phase condensation of pyrrole and benzaldehyde to ms‐tetraphenylporphin in acidic media were undertaken. The role of atmospheric oxygen in the reaction was studied in some detail. The effects of acidity, solvent, concentration, and other constraints on both the rate and yield of the reaction were also investigated. Details of the mechanism, including possible intermediate structures, have been clarified and a reaction scheme accounting for the data is presented.
Proton resonance spectra of heterocycles. VI. Chromanones, thiochromanones, and 2,3‐dihydro‐4‐quinolones
Authors: Katritzky A. R. , Ternai B. 
Published: April 2009

AbstractThe nmr spectra of the title compounds and some substituted derivatives are recorded and discussed. It is concluded that 3‐halogeno substituents probably occupy largely pseudo axial positions whereas a 3‐methyl group is predominantly pseudo equatorial.
Chemistry of thienopyridines. IV. Syntheses of 5‐substituted thieno[2,3‐b] pyridines
Authors: Klemm L. H. , Zell Reinhard 
Published: April 2009

AbstractChemical transformations on 5‐acetylthieno[2,3–6] pyridine produced 5‐NH2, 5‐CO2H, and 5‐CH2 CO2H substituents. The 5‐amino compound underwent facile diazotization (plus Sand‐meyer reaction), Schiff's base formation, and acylation. Treatment of the derived 5‐bromo compound with potassium amide in liquid ammonia gave a mixture of 4‐amino (major) and 5‐amino isomers. Nmr spectral data are reported for the 5‐substituted thieno [2,3‐b] pyridine system.
Steroid derivatives of purine‐6(1H)‐thione (1a‐c)
Authors: Carroll F. I. , Philip Abraham , Ferguson Anna M. , Wall Monroe F. 
Published: April 2009

AbstractThe products obtained as a result of the alkylation of purine‐6(1H)‐thione, and 6‐alkylthiopurines with steroidal‐21‐(p‐bromobenzenesullonates) (H) and 3‐methoxy‐16α‐bromoestra‐1,3,5 (10)‐tricne‐17‐one (IV) is reported. The ratio of 9‐alkylated to 7‐alkylated purine in the alkylation of 6‐methylthiopurine (VI) is presented. The use of the S‐diphenylmethylprotecling group in the syntheses of sensitive 9‐steroidal‐9H‐purine‐6(1H)‐thiones is discussed.
Infrared and nuclear magnetic resonance properties of benzoyl derivatives of five‐membered monoheterocycles and determination of aromaticity indices
Authors: Jeon Kyu Ok , Jun Jung Ho , Yu Ji Sook , Lee Chang Kiu 
Published: April 2009

AbstractBenzophenones, 2‐benzoylthiophenes, 2‐benzoylpyrroles, and 2‐benzoylfurans, which have substituents at m‐ and p‐positions of the benzoyl ring were prepared and their ir and nmr spectra were obtained in 0.1 M chloroform‐d solution. The chemical shift values of each series were plotted against the Hammett substituent parameters to give good correlation, with the exception of the ortho‐Hs and ‐Cs. The slopes as well as the differences in chemical shift gave sets of meaningful values for the indices of aromaticy.
Synthesis of novel 1,4‐dihydropyrido[3′,2′:5,6]thiopyrano[4,3‐c]‐pyrazoles and 5H‐pyrido[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines as potential antiproliferative agents
Authors: Primofiore Giampaolo , Marini Anna Maria , Da Settimo Federico , Salerno Silvia , Bertini Daniele , Dalla Via Lisa , Magno Sebastiano Marciani 
Published: April 2009

AbstractThe synthesis of new planar derivatives characterized by the presence of a pyridothiopyranopyrazole or pyridothiopyranopyrimidine nucleus, carrying a substituted aryl group, is reported. The novel 1,4‐dihydropyrido[3′,2′:5,6]thiopyrano[4,3‐c]pyrazole derivatives were obtained by condensation of 2,3‐dihydro‐3‐hydroxymethylenethiopyrano[2,3‐b]pyridin‐4(4H)‐ones with appropriate hydrazines. The preparation of 2‐substituted pyrido[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines was accomplished from the intermediate 2,3‐dihy‐dro‐3‐dimethylaminomethylenethiopyrano[2,3‐b]pyridin‐4(4H)‐ones by reaction with the appropriate binucleophile amidines. The antiproliferative activity of some new products was tested by an in vitro assay on human tumour cell lines (HL‐60 and HeLa), but none of them showed any significant effects in the tests performed. Accordingly, linear flow dichroism measurements indicated their inability to form a molecular complex with DNA.
New trans/cis tetrahydroisoquinolines. 2. trans‐ and cis‐3‐(1‐methyl‐1h‐pyrrol‐2‐yl)‐1‐(2H)‐oxo‐2‐phenethyl‐1,2,3,4‐tetrahydroisoquino‐lin‐4‐carboxylic acids and subsequent transformations
Authors: Stoyanova M. P. , Kozekov I. D. , Palamareva M. D. 
Published: April 2009

AbstractStereochemical course of the reaction of homophthalic anhydride and N‐(1‐methyl‐1H‐pyrrol‐2‐yl‐methylidene)‐phenethylamine was studied. Mixtures of the expected trans‐ and cis‐1,2,3,4‐tetrahydroiso‐quinoline‐4‐carboxylic acids trans‐4 and cis‐4 were obtained along with by‐products 5 and 6. The ratios of all products and the diastereomers, obtained under different reaction conditions, were established by pmr. THF as a solvent and ultrasonic treatment are applied for the first time in the reaction of this type. The reaction was made diastereoselective towards any isomer. The carboxylic group of trans‐4 was transformed in four steps into various cyclic amino‐methyl groups yielding numerous new tetrahydroisoquinolinones trans‐10a‐i incorporating a given fragment of pharmacological interest. Reduction of 10a‐i was studied.
On triazoles XLVII. Synthesis of 1,3a,5,6,ωc‐pentaazacycloalka[e]acenaphthylenes
Authors: Berecz Gábor , Reiter József 
Published: April 2009

AbstractTo study the influence of planar or bulky cycloalkane rings attached to the 1,3a,5,6,ωc‐pentaazaacen‐aphthylenes to the reactivity of their 4‐alkylthio group toward amines ‐ an unexpected reaction observed recently at 1,3a,5,6,10c‐pentaazaacephenanthrylenes (5b, n = 4) ‐ different size 1,3a,5,6,ωc‐pentaazacyclo‐alka[e]acenaphthylenes (5a, n = 3; 5c, n = 5; 5d, n = 6; or 5e, n = 10) were synthesised and their spectral data compared with that of 5b (n = 4). Based on the analogy of the chemical shifts of carbon atoms at position 4 with that of 5b, similar electronic structure and thus a possibility of an analogous nucleophilic attack of amines was proposed and subsequently proved by a preparative method.
Quinolone analogues 6 [1‐5]. Synthesis of 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones
Authors: Kurasawa Yoshihisa , Satoh Waka , Matsuzaki Izumi , Maesaki Yuka , Okamoto Yoshihisa , Kim Ho Sik 
Published: April 2009

AbstractThe reaction of the quinoxaline N‐oxides 7a,b with diethyl ethoxymethylenemalonate gave the 1‐methylpyridazino[3,4‐b]quinoxaline‐4,4‐dicarboxylates 8a,b, whose reaction with N‐bromosuccinimide or N‐chlorosuccinimide afforded the 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxaline‐4,4‐dicarboxylates 9a‐d. The reaction of compounds 9a‐d with hydrazine hydrate resulted in hydrolysis and decarboxylation to provide the 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxaline‐4‐carboxylates 10a‐d, whose reaction with nitrous acid effected oxidation to furnish the 3‐halogeno‐4‐hydroxy‐1‐methylpyridazino[3,4‐b]quinoxaline‐4‐carboxylates 11a‐d, respectively. The reaction of compounds 11a‐d with hydrazine hydrate afforded the 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxalin‐4‐ols 12a‐d, whose oxidation provided the 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones 6a‐d, respectively. Compounds 6a‐d had antifungal activities in vitro.
Synthesis of thiophene/phenylene co‐oligomers. IV. 6‐ to 8‐ring molecules
Authors: Hotta Shu , Katagiri Toshifumi 
Published: April 2009

AbstractWe report the synthesis of various thiophene/phenylene co‐oligomers with a total number of thiophene and benzene (phenylene) rings of 6 to 8. These compounds include a phenyl‐capped sexithiophene, a thienyl‐capped quaterphenylene, as well as block and alternating co‐oligomers. The synthesis is based on either the Suzuki coupling reaction or the direct dimerization coupling. The latter method produces symmetric molecules with an even total ring number. These reaction schemes enabled us to obtain the target compounds in high quality. Although the resulting materials are difficult to dissolve in organic solvents and therefore difficult to identify by usual 1H nmr spectroscopy, they have successfully been identified through Fourier‐transform ir spectroscopy. The specific group frequencies of ring‐stretching and out‐of‐plane deformation modes are characteristic of the substitution pattern of the individual thiophene and benzene rings.