bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, X‐ray crystal structure determination and antiinflammatory activity of the regioisomers: 5‐phenyl‐6‐(4‐pyridyl)‐2,3‐dihydroimidazo[2,1‐b]thiazole and 6‐phenyl‐5‐(4‐pyridyl)‐2,3‐dihydroimidazo[2,1‐b]thiazole. A structural reassignment
Authors: Shilcrat Susan C. , Hill David T. , Bender Paul E. , Griswold Don E. , Paul W.  , Eggleston Drake S. , Lantos Ivan , Pridgen Lendon N.
Published: March 2009

A regiospecific synthesis of 6‐phenyl‐5‐(4‐pyridyl)‐2,3‐dihydroimidazo[2,1‐b]thiazole (2) was accomplished by treatment of 6‐phenyl‐2,3‐dihydroimidazo[2,1‐b]thiazole (10) with the reactive complex of pyridine and ethyl chloroformate followed by oxidation with chromium(VI) oxide. Reaction of 4‐phenyl‐5‐(4‐pyridyl)imidazole‐2‐thione (12) with 1,2‐dibromoethane in the presence of base also gave 2 together with its regioisomer 3. The structures of 2 and 3 were confirmed by X‐ray crystallography. Evaluation, on oral administration, in a one hour arachidonic acid‐induced mouse ear inflammation assay, showed the inhibition of edema by 2 (48%) and 3 (34%) to be less than that of the 6‐(4‐fluorophenyl) analog 1 (SK&/F 86002) (69%), a known antiinflammatory agent.
Synthesis of new heterocyclic phenols: 9‐Hydroxypyrido[1,2‐a]pyrimidin‐4‐one and Derivatives
Authors: Dennin F. , Blondeau D. , Sliwa H.
Published: March 2009

9‐Hydroxypyrido[1,2‐a]pyrimidin‐4‐one (5) was prepared by condensation of 2‐amino‐3‐hydroxypyridine with isopropylidene aminomethylenemalonate. The reaction first led to an enaminoester intermediate which underwent cyclization by heating at 250° affording the new heterocyclic phenol 5. A similar condensation performed on 2‐amino‐3‐benzyloxypyridine yielded the corresponding benzylic ether which can be easily debenzylated to 5 by hydrogenolysis. Furthermore 2‐amino‐3‐benzyloxypyridine condensed with diethyl ethoxymethylenemalonate gave 9‐benzyloxy‐3‐ethoxycarbonylpyrido[1,2‐a]pyrimidin‐4‐one which was also debenzylated to the corresponding free phenol.
Assignment of the proton and carbon NMR spectra of the indoloquinoline alkaloid cryptolepine
Authors: Tackie Albert N. , Sharaf Maged H. M. , Schiff Paul L. , Boye Gilbert L. , Crouch Ronald C. , Martin Gary E.
Published: March 2009

The relatively rare alkaloid cryptolepine, 5‐methyl‐5H‐indolo[3,2‐b]quinoline, was isolated from Cryptolepis sanguinolenta (Lindl.) Schlecter (Asclepiadaceae). Unequivocal proton and carbon nmr assignments in dimethyl sulfoxide are reported based on two‐dimensional nmr methods, including COSY, inverse‐detected direct (HMQC), and long‐range (HMBC) correlations. Several of the assignments were confirmed using one‐dimensional SIMBA spectra ‐ a new, selective, one‐dimensional analogue of the proton‐detected long‐range heteronuclear shift correlation experiment (HMBC). The SIMBA experiment was also used in an attempt to observe a two‐bond coupling from the H11 proton to C10a at several optimizations.
A photochemical synthesis of 3‐aryl‐1‐methylquinolinones
Authors: Meng Ji‐Ben , Shen Mei‐Qen , Wang Xiao‐Hong , Kao Chen‐Heng , Wang Ru‐Ji , Wang Hong‐Gen , Matsuura Teruo
Published: March 2009

A number of fluorescent 3‐aryl‐1‐methylquinolinones 3 were synthesized by the regiospecific photocoupling reaction of 3‐halo‐1‐methylquinolinones 1 with aromatic and heteroaromatic compounds 2. An unusual photocoupling product 4 was obtained in the photolysis of 3‐iodo‐1‐methylquinolinone in the presence of benzene. The structure of 4 was unequivocally established by an X‐ray crystallographic analysis.
Identification of some isomeric 3,5‐unsymmetrically substituted 1‐aroyl‐pyrazole derivatives by NMR spectroscopy
Authors: Mitkidou Sophia , Papadopoulos Stelios , Stephanidou‐Stephanatou Julia
Published: March 2009

The 1H and 13C nmr chemical shifts are used for the structural assignment of isomeric 1‐aroyl‐4,5‐dihydro‐5‐hydroxy‐4,4‐dimethyl‐1H‐pyrazoles 1 unsymmetrically substituted with phenyl or methyl in the 3,5‐positions of the pyrazole ring. The 1H nmr spectra of 1‐aroyl‐ or 1‐acetyl‐4‐methyl‐1H‐pyrazoles 2 are useful in structure elucidation of unsymmetrically 3‐ or 5‐methyl substituted derivatives.
Synthesis of 2‐amino‐2‐deoxo‐5‐deazaflavins and related compounds
Authors: Aoyagi Takeshi , Yanada Reiko , Bessho Kiyoshi , Yoneda Fumio , Armarego W. L. F.
Published: March 2009

10‐Alkyl‐2‐amino‐2‐deoxo‐5‐deazaflavins were prepared by the condensation of 2‐amino‐6‐chloro‐5‐formylpyrimidin‐4(3H)‐one with the corresponding N‐alkylanilines. 2‐Amino‐10‐p‐tolyl‐2‐deoxo‐5‐deazaflavin was prepared by the condensation of 2‐amino‐6‐p‐toluidinopyrimidin‐4(3H)‐one with o‐chlorobenzaldehyde. Some reactivities of 2‐aminopyrimidin‐4(3H)‐ones are described.
Synthesis of various 5‐arylsubstituted cytosines
Authors: Peters Dan , Hörnfeldt Anna‐Britta , Gronowitz Salo
Published: March 2009

Some Pd‐catalyzed coupling reactions have been evaluated for the synthesis of 5‐substituted cytosines. A large number of 5‐arylcytosines were prepared in good yields by using 2,4‐O,N‐bis‐trimethylsilyl‐5‐iodocytosine with various aryl tin compounds. The use of trimethylsilyl groups proved to be essential for the reaction, attempted coupling of 5‐iodocytosine and 2‐trimethylstannylthiazole was not successful. One convenient alternative, which unfortunately was not successful, would have been to reverse the coupling functionalities and couple commercial arylhalides with 5‐trimethylstannyl‐ or 5‐tributylstannyl‐derivatives or the corresponding 2,4‐O,N‐bis‐trialkylsilylcytosines.
Reactivity of 3‐alkyl‐4‐arylazomethylene‐3,4‐dihydro‐1,2,3‐benzotriazines in protic solvents: 1,4‐Addition reactions and dimroth rearrangement
Authors: Vaughan Keith , LaFrance Ronald J. , Tang York , Hooper Donald L.
Published: March 2009

3‐Alkyl‐4‐arylazomethylene‐3,4‐dihydro‐1,2,3‐benzotriazines 5a and 5b undergo facile 1,4‐addition of methanol or ethanol to afford stable crystalline hydrazones, 6 and 8 which have been characterised by spectroscopic analysis. In particular, the nmr spectrum of 8 shows novel features due to the diastereotopic nature of the CH2 protons in the two O‐ethyl groups. Compound 5b shows a property unique to the compounds in this series; refluxing this arylazomethylenetriazine in ethanol affords a rearranged product, characterised as the 1‐aryl‐2‐cinnolinylhydrazine (9). The formation of 9 is rationalised as a ring opening‐ring closure process analogous to the Dimroth rearrangement. The cinnoline 9 displays some novel chemistry arising from the facility of the arylhydrazino substituent to react with acid to give a fragmentation product, 3‐methylindazole (7).
Condensation of homophthalic anhydrides with heterocyclic imines and DMAD under mild conditions
Authors: Smith Forrest T. , Atigadda Ram V.
Published: March 2009

Condensation of 7‐methoxyhomophthalic anhydride with 2‐imidazoline, 2‐thiazoline, 2‐oxazoline, 1‐pyrroline trimer and DMAD (with triethylamine) occurs rapidly under mild conditions.
On the boulton‐katritzky rearrangement of 5,6‐ and 6,7‐Dimethoxy‐4‐nitrobenzofuroxans: A reinvestigation
Authors: Takakis Ioannis M. , Hadjimihalakis Phaedon M.
Published: March 2009

5,6‐Dimethoxy‐4‐nitrobenzofuroxan (6) or its 6,7‐isomer 7 equilibrate on heating to a 66:34 = 6:7 thermostationary mixture, in contrast to a previous report. The systems 6:7 and 1f:2f are compared.
Amino acids in the synthesis of heterocyclic compounds. Transformations of thiazolones into imidazole derivatives
Authors: Copar Anton , Stanovnik Branko , Tisler Miha
Published: March 2009

5(4H)‐Thiazolone derivative 4, obtained from N‐dithiocarbobenzoxyglycine (1) and N,N‐dimethyl‐N′‐heteroarylformamidines 3 in acetic anhydride, was rearranged with sodium methoxide in methanol followed by acidification with acetic acid into imidazole‐4‐carboxylic acid derivatives 5, 6 and 7. These were further converted with methyl iodide into methylthio derivatives 8, with hydrogen peroxide into the corresponding disulphide 9, with hydrazine and amines into hydrazide 10 and amides 11. In the reactions of 4a and 6a with amines in the presence of dichloromethane symetrically disubstituted methanes 14–18 were formed.
Assembled systems [X‐azolopyridine][quinoline]. Bases and salts
Authors: Savarino Piero , Viscardi Guido , Barni Ermanno , Di Modica Gaetano , Montoneri Enzo , Quagliotto Pierluigi
Published: March 2009

A series of bases containing X‐azolopyridines (X = O, NH) and methylquinolines, assembled in different ways, was prepared by reaction of methylquinolinecarboxylic acids (or carboxamides) with diamino (or hydroxyamino) pyridines. The bases were quaternized with methyl iodide. The physical and spectroscopic data of both the bases and the salts were correlated and compared with those of [X‐azolopyridine][pyridine] systems previously studied. The structure of the salts was markedly influenced by a balance of basicity‐hindrance factors in the heteroaromatic substrates.
Structure determination of some 5,6‐dihydropyrrolo‐[1,2‐a][3,1,6]benzothiadiazocines
Authors: Cobb J. , Demetropoulos I. N. , Skoulika S. , Varvounis G. , Aubry A.
Published: March 2009

The conformation of compounds 1 and 2 has been determined in the solid state by X‐ray crystallography and in solution by nmr spectroscopy. MM2 and molecular dynamics calculations were used to determine the conformation of compound 2 in vacuo and in solution.
Crystallographic analysis of a pair of isolable atropisomers of 2‐aryl substituted indoline derivatives
Authors: Eto Masashi , Harano Kazunobu , Hisano Takuzo , Kitamura Takeo
Published: March 2009

The crystal and molecular structures of isomeric compounds of 1‐(4′‐chlorobenzoyl)‐2‐(2″‐hydroxynaphthyl)‐3,3‐Dimethylindoline have been determined by single crystal X‐ray analyses as a pair of diastereomeric atropisomers due to restricted rotation about a Csp3‐Csp2 bond.
Oxidative halogenation of substituted pyrroles with Cu(II). Part III. Bromination and chlorination of 2‐benzoylpyrrole
Authors: Petruso S. , Caronna S.
Published: March 2009

The bromination of 2‐benzoylpyrrole with copper(II) bromide in the homogeneous and the heterogeneous phase is described, giving 4‐ and 5‐monobromo derivatives whose ratio decreases as the temperature is increased. The same reaction with copper(II) chloride in acetonitrile at 60° produces 5‐chloro‐2‐benzoylpyrrole as the major product. 4,5‐Dihalopyrroles in good yields are obtained with an excess of halogenating agent.
Halovinylsulfones 4. Synthesis and some reactions of 2‐phenylsulfonyl‐2‐propenyl isothiocyanate
Authors: Yamamoto Iwao , Kajiwara Kouji , Fujimoto Tetsuya , Ohta Kazutika
Published: March 2009

The title compound, isothiocyanate 2, was obtained in good yield from the reaction of α‐chloromethylvinyl‐sulfone 1 with lead thiocyanate. The isothiocyanate 2 was reacted with aromatic amines to give 2‐amino‐5,6‐dihydro‐4H‐1,3‐thiazines 3 in good to moderate yields. The formation pathways are discussed.
Spectroscopic study of 3‐methyl‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonan‐9‐α(β)‐ols
Authors: Iriepa I. , Gil‐Alberdi B. , Galvez E.
Published: March 2009

3‐Methyl‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonan‐9‐α(β)‐ols have been synthesized and studied by ir, 1H and 13C nmr spectroscopy. In deuteriochloroform and perdeuteriobenzene solutions, these compounds adopt a flattened chair‐chair conformation in which the cyclohexane ring is more flattened.

From the 1H and 13C nmr data, several stereoelectronic effects have been deduced. The complete and unambiguous assignment of all protons of the 3‐azabicyclo[3.3.1]nonane system, not described up to date, has been carried out.
Pyrrolization processes of vinyl substituted imidazo[1,2‐a]pyridine, pyrimidine and 1,8‐naphthyridine
Authors: Chavignon O. , Teulade J. C. , Madesclaire M. , Gueiffier A. , Blache Y. , Viols H. , Chapat J. P. , Dauphin G.
Published: March 2009

A general synthesis for the preparation of a series of N‐bridgehead compounds: pyrroloimidazopyridine, pyrimidine and naphthyridine has been developed beginning with azidovinyl compounds with thermolytic or photochemical methods
New synthesis of 5‐amino‐5‐deazaflavin derivatives by direct coupling of 5‐deazaflavins and amines
Authors: Kimachi Tetsutaro , Yoneda Fumio , Sasaki Takuma
Published: March 2009

5‐Amino‐5‐deazaflavin derivatives are newly synthesized by direct coupling of 5‐deazaflavins and amines. Some of them revealed potential activity toward tumor cells such as L1210 or KB cells.
Synthesis of quinazoline derivatives through anionic cycloaddition reactions of methyl 2,4‐dimethoxy‐6‐methyl‐5‐pyrimidinecarboxylate with acetylenes and olefins
Authors: Wada Akimori , Yamamoto Hiromi , Ohki Kazuhiro , Nagai Sotoo , Kanatomo Shoichi
Published: March 2009

The anionic cycloaddition of methyl 2,4‐dimethoxy‐6‐methyl‐5‐pyrimidinecarboxylate has been investigated. The lithium salt of methyl 2,4‐dimethoxy‐6‐methyl‐5‐pyrimidinecarboxylate, generated by deprotonation with lithium diisopropylamide in ether at – 70°, reacted smoothly with electron deficient acetylenes and olefins to give quinazoline derivatives in a single step.
Axially chiral heteroaromatics. 1. Preparation of optically active 1,1′‐biisoquinoline N,N'‐dioxide
Authors: Fujii Masayuki , Honda Akihiro
Published: March 2009

A novel optically active heteroaromatic compound, (+)‐1,1′‐biisoquinoline N,N′‐dioxide (1) and its atropisomer (‐)‐1 were prepared and characterized by several spectroscopic methods.
Novel routes to 1‐aryl‐1,4‐dihydro‐3(2H)‐isoquinolinones and 2‐substituted or 2,3‐disubstituted benzofurans by intramolecular cyclizations
Authors: Katritzky Alan R. , Lan Xiangfu , Zhang Zhongxing
Published: March 2009

N‐(α‐Benzotriazolylalkyl)arylacetamides, readily available from an arylacetamide, an aldehyde and benzotriazole, undergo intramolecular cyclization under acidic conditions to give 1‐aryl‐1,4‐dihydro‐3(2H)‐isoquinolinones in good to excellent yields. Similarly, 2‐(benzotriazol‐1‐yl)‐2‐(o‐hydroxyphenyl)ethanols, obtained by lithiation of 2‐(benzotriazol‐1‐ylmethyl)phenols followed by quenching with aldehydes or ketones, eliminate a molecule of water and a molecule of benzotriazole yielding 2‐substituted and 2,3‐disubstituted benzofurans.
The reactions of 5‐aryl‐2,3‐dimethylisoxazolium salts with aromatic aldehydes
Authors: Alberola Angel , Manuel Bañez J. , Calvo Luis , Rodríguez Rodríguez M. Teresa , Carmen Sañudo M.
Published: March 2009

The reactions of the 3‐methyl group in 5‐aryl‐2,3‐dimethylisoxazolium tetrafluoroborates with aromatic aldehydes, in the presence of piperidine were studied. Isoxazolium salt reactivity is independent of the phenyl group substituent at C‐5 on the isoxazolium salt ring. However, it does depend on the aldehyde structure.
The Synthesis of Novel Polycyclic Heterocyclic Ring Systems via Photocyclization. 12. Benzo[h]naphtho‐[2′,1′:4,5]thieno[2,3‐c]quinoline and benzo[f]‐naphtho[2′,1′:4,5]thieno[2,3‐c]quinoline
Authors: Luo Jiann‐Kuan , Castle Steven L. , Castle Raymond N.
Published: March 2009

The synthesis of two previously unknown heterocyclic ring systems, namely benzo[h]naphtho[2′,1′:4,5]thi‐eno[2,3‐c]quinoline (1) and benzo[f]naphtho[2′,1:4,5]thieno[2,3‐c]quinoline (2) was accomplished via photocyclization of the appropriate amides followed by chlorination and catalytic dechlorination. The total assignment of 1H and 13C nmr spectra of 2 was determined utilizing two‐dimensional nmr methods, providing unequivocal structural proof of the two novel polycyclic ring systems.
On the reaction between 3H‐1,2‐dithiolo[3,4‐b]pyridine‐3‐thione and primary alkyl and arylalkylamines
Authors: Borgna Pietro , Pregnolato Massimo , Invernizzi Anna Gamba , Mellerio Giorgio
Published: March 2009

3H‐1,2‐Dithiolo[3,4‐b]pyridine‐3‐thione (10) reacts with primary alkylamines to give 1,2‐dihydro‐2‐thioxo‐3‐pyridinecarbothioamides 11a‐g and two minor products. Isothiazolo[5,4‐b]pyridine‐3(2H)‐thiones 12a‐g and 3‐imino‐3H‐1,2‐dithiolo[3,4‐b]pyridines 13a‐g were isolated and characterized. Further investigations allowed the synthesis of 12 and 13 in good yield.
The synthesis of 6,9‐bis[(aminoalkyl)amino] substituted benzo[g]quinoxaline‐, benzo[g]quinazoline‐ and benzo‐[g]phthalazine‐5,10‐diones via regiospecific displacements
Authors: Krapcho A. Paul , Maresch Martin J. , Helgason Anna L. , Rosner Kristin E. , Hacker Miles P. , Spinelli Silvano , Menta Ernesto , Oliva Ambrogio
Published: March 2009

The synthesis of 6,9‐difluoro substituted benzo[g]quinoxaline‐5,10‐diones (3A), benzo[g]quinazoline‐5,10‐diones (3B) and benzo[g]phthalazine‐5,10‐diones (3C) have been accomplished. Treatment of 3A, 3B or 3C with diamines or N‐(t‐butoxycarbonyl)ethylenediamine led to the corresponding 6,9‐bis[(aminoalkyl)amino]‐substituted analogues related to 2A, 2B and 2C, respectively. The mono‐substituted derivatives 4h and 4i could be isolated from displacements commencing from 3A. A competitive ring‐opening of the pyrimidine ring of 2C occurred during the reaction with N,N‐dimethylethylenediamine. Removal of the BOC‐protecting group from 2Ac led to the hydrochloride salt 2Ab. A novel synthetic pathway to 6,9‐dihydroxybenzo[g]‐phthalazine‐5,10‐dione (21a) was developed. Conversion of 21a to the ditosylate 21b was readily accomplished. Treatment of 21b with N,N‐dimethylethylenediamine or N‐(t‐butoxycarbonyl)ethylenediamine led to 2Ca and 2Cc, respectively. Removal of the BOC‐protecting group from 2Cc with trifluoroacetic acid followed by ion‐exchange led to the hydrochloride salt 2Cb. Treatment of ditosylate 21b with N‐(t‐butoxycar‐bonyl)ethylenediamine also led to the mono‐substituted analogue 25a along with a small amount of the O‐S cleavage product 25b. Treatment of 25a with N,N‐dimethylethylenediamine led to the unsymmetrically substituted derivative 25c which was converted into the trifluoroacetate salt 25d.
A reexamination of the reactions of 2,3‐dichloro‐1,4‐naphthoquinone with thioamides
Authors: Katritzky Alan R. , Fan Wei‐Qiang
Published: March 2009

2,3‐Dichloro‐1,4‐naphthoquinone reacts with thioamides and thiourea to give mixtures of condensed thiazoles and thianthrenes.
Complete assignment of the 1h‐ and 13c‐nmr spectra of [1]benzothieno[2,3‐c]naphtho[1,2‐h]quinoline and [1]benzothieno[2,3‐c]naphtho[1,2‐h][1,2,4]triazolo[4,3‐a]quinoline. Concerted use of two‐dimensional nmr techniques
Authors: Sasaki Kenji , Castle Lyle W. , Castle Raymond N.
Published: March 2009

The 1H‐ and 13C‐nmr spectra of [1]benzothieno[2,3‐c]naphtho[1,2‐h]quinoline and [1]benzothieno[2,3‐c]‐naphtho[1,2‐h][1,2,4]triazolo[4,3‐a]quinoline were totally assigned using a combination of two‐dimensional nmr techniques. After correlation of the proton signals by a COSY spectrum and one‐bond heteronuclear correlation, complete assignment of the 1H‐ and 13C‐nmr spectra of the novel heterocyclic compounds required the application of long‐range CH coupling information particularly for quarternary resonance assignments and the orientations of individual spin systems relative to one another.
Amino acids in the synthesis of heterocyclic systems. The synthesis of 4‐oxo‐4H‐pyrido[1,2‐a]pyridines and 4‐oxo‐4H‐pyrido[1,2‐a]pyrimidines
Authors: Smodiŝ Janez , Stanovnik Branko , Tiŝler Miha
Published: March 2009

The pyridine and quinoline derivatives 2, 3, and 6 with an activated methylene group atα‐position in respect to the ring nitrogen atom were converted with 1, 8, or 9 into fused pyrido[1,2‐a]pyridine derivatives 4, 5, 7, and 10. In an analogous manner were the aminopyridines 16 and 17 transformed with thiazolone 9 into pyrido[1,2‐a]pyrimidine derivatives 20, 21, 25, and 26.
Structural study of alkaloids from securidaca longipedunculata roots. II. Isolation and characterization by supercritical fluid chromatography/mass spectrometry
Authors: Scandola Marina , Games David E. , Costa Carlo , Allegri Graziella , Bertazzo Antonella , Curcuruto Ornella , Traldi Pietro
Published: March 2009

Various alkaloids obtained from the methanol extracts of the roots of Securidaca Longipedunculata Fres. were studied using supercritical fluid chromatography/mass spectrometry. This hyphenated method and parallel unimolecular and collisionally activated decomposition experiments on electron impact‐generated molecular ions gave information on the structure of compounds. The presence of the ergoline skeleton in some of them was assigned.
Novel syntheses of 1,3,3‐trinitroazetidine
Authors: Katritzky Alan R. , Cundy Darren J. , Chen Jie
Published: March 2009

Alternative methods for the synthesis of 1,3,3‐trinitroazetidine (TNAZ) from epichlorohydrin, and benzhydrylamine have been developed. These approaches employ N‐sulfonyl‐3‐(hydroxyimino)azetidines as penultimate intermediates and represent an improvement over previously published methods which require either diazo containing intermediates or involve low yielding procedures. Parallel methods employing N‐benzhydryl‐ and N‐benzyl‐3‐(hydroxyimino)azetidine were also investigated as alternate routes to TNAZ.
Substituent and solvent effects on the tautomer ratios between the hydrazone imine and diazenyl enamine forms in p‐ and m‐substituted 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines
Authors: Kurasawa Yoshihisa , Hosaka Tomoyoshi , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa
Published: March 2009

The p‐ and m‐substituted 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines 1a‐i and 2a‐d exhibited tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in a series of mixed dimethyl sulfoxide/trifluoroacetic acid media. The substituent and solvent effects on the tautomer ratios of A to B in a series of mixed media were studied for compounds 1a‐i and 2a‐d by the nmr spectroscopy. The linear correlation of the Hammett σp and σm values with the tautomeric equilibrium constants KT ([A]/[B]) was found in the dimethyl sulfoxide media of compounds 1a‐i and 2b‐d. On the other hand, the linear correlation of the Hammett σp and σm values with the log C'(A:B = 1:1) was also observed in a series of mixed media of compounds 1a‐h and 2a‐c, wherein C'(A:B = 1:1) indicated the concentrations of trifluoroacetic acid (mol/l) giving 1:1 tautomer ratios in a series of mixed media. The increase in the Hammett σp or σm values decreased the KT values in dimethyl sulfoxide media and augmented the C'(A:B = 1:1) values in a series of mixed media. The Hammett σp or σm values controlled the electron density of the side chain nitrogen atom, which influenced the C'(A:B = 1:1) values. In the KT value temperature dependence, the higher temperature provided the larger KT values in dimethyl sulfoxide media regardless of the Hammett σp or σm values.
Synthesis and spectral properties of 6H‐1‐(2‐, 3‐ and 4‐R‐Phenyl)‐2,7,7‐trimethyl‐4,5,7,8‐tetrahydropyrrolo[3,2‐c]azepin‐4‐ones
Authors: Martínez Roberto , López Gema , Gustavo Avila Z. J.
Published: March 2009

The preparation of novel 4,5,7,8‐tetrahydropyrrolo[3,2‐c]azepin‐4‐ones is described. The structure of all the products was corroborated by ir, mass spectrometry and 1H and 13C‐nmr.
A semiempirical conformational analysis of the 3‐phenyl‐1,2,3‐oxathiazolidine 2‐oxide
Authors: Do Val Amelia M. G. , Guimarães Afonso C. , De Almeida Wagner B.
Published: March 2009

An extensive conformational search for the heterocyclic compound 3‐phenyl‐1,2,3‐oxathiazolidine 2‐oxide has been carried out using the semiempirical quantum‐mechanical method PM3. All torsion angles were varied in the geometry optimization procedure which led to the prediction of four distinct conformers. Barriers to internal rotation leading to conformational interconversions were also calculated. The results of the present study indicate that this five‐member ring substituted heterocyclic system may be expected to exist as a mixture of stable conformers rather than a unique molecular entity.
New hypoxia‐selective cytotoxines derived from quinoxaline 1,4‐dioxides
Authors: Monge A. , Palop J. A. , González Mercedes , Martínez‐Crespo F. J. , De Ceráin Adela López , Sáinz Yolanda , Narro Susana , Barker A. J. , Hamilton E.
Published: March 2009

A new series of quinoxaline 1,4‐dioxides, structurally related to the benzotriazine tirapazamine 1 have been prepared starting from 5,6‐dichlorobenzofuroxane 2. The Beirut reaction between 2 and alkyl or aryl thiopropanones afforded the 2‐methyl‐3‐alkyl(aryl)thioquinoxaline 1,4‐dioxides 3a‐3e. Selective oxidation of 3 with m‐chloroperbenzoic acid yielded the sulphinyl 4a‐4c and sulphonyl 5a‐5b derivatives. Replacement of the sulphonyl group of 5a by chlorine or bromine gave 6 or 7, while nucleophilic displacement by 3‐(N,N‐dimethylamino)propylamine afforded 8. A dimer 9 was prepared from 5a and hydrazine hydrate. The methylthio group of 3a was replaced by using formamidine acetate giving the amino compound 10. Bromination of the methyl group of 3b afforded 11, which reacted with 2‐aminoethanol giving 12. Compounds were tested as cytotoxic agents both in oxic and in hypoxic cells.
7‐(2‐fluorobenzyl)‐4‐(substituted)‐7‐H‐imidazo[4,5‐d −1,2,3‐triazines and −7H‐pyrazolo[3,4‐d]‐1,2,3‐triazines. Synthesis and anticonvulsant activity
Authors: Kelley James L. , Wilson David C. , Styles Virgil L. , Soroko Francis E. , Cooper Barrett R.
Published: March 2009

The imidazo[4,5‐d]‐1,2,3‐triazine and pyrazolo[3,4‐d]‐1,2,3‐triazine analogues of the potent anticonvul‐sant purine, BW 78U79 (9‐(2‐fluorobenzyl)‐6‐methylamino‐9H‐purine, 1), were synthesized and tested for anticonvulsant activity. The imidazo[4,5‐d]‐1,2,3‐triazines 11–13 were prepared in four steps from 5‐aminoimidazole‐4‐carboxamide (2) and the pyrazolo[3,4‐d]‐1,2,3‐triazines 18–21 were synthesized starting with 5‐amino‐1‐(2‐fluorobenzyl)pyrazole‐4‐carbonitrile (14). The intermediate 1,2,3‐triazin‐4‐ones 6 and 16 were converted to the 4‐substituted targets via the 4‐(4‐dimethylaminopyridinium) salts 10 and 17. Imidazotriazine 11 had potent anticonvulsant activity against maximal electroshock‐induced seizures, but its propensity to cause emesis precluded further development.
Comparison of the reactivity of thiophene, thiophene 1‐oxide, and thiophene 1,1‐dioxide as diene for diels‐alder reactions. An ami semiempirical study
Authors: Jursic Branko S.
Published: March 2009

A semiempirical AMI theoretical study was carried out to examine the very low reactivity of thiophene; for example, the high reactivity of thiophene 1‐oxide as a diene in the Diels Alder reactions. The reactivities of cyclopentadiene, thiophene, thiophene 1‐oxide, and thiophene 1,1‐dioxide were studied as dienes in the reaction with ethylene, cyclopropene, and benzoquinone. Ethylene was chosen as a standard, while cyclopropene, with its high strain energy was released in the course of a reaction making it relatively reactive. The benzoquinone has a lower LUMO energy, making it a very reactive dienophile for the Diels‐Alder reaction. Frontier molecular orbital energy gap between the reactants was considered, and the disadvantage of this approach in studying the reactivity was demonstrated. For all combinations, the corresponding transition structures are generated and the activation energies are estimated. The estimated activation barrier for sulfur dioxide elimination from the adduct was used to explain the failure to accumulate the cycloadduct in the reaction mixture. The obtained results are compared with experimental data when available. An excellent agreement of theory and experiment was obtained.
A novel synthesis of 5‐acylaminooxazoles
Authors: Katritzky Alan R. , Wu Hong , Xie Linghong
Published: March 2009

1,2‐Diacylamino‐1,2‐di(benzotriazol‐1‐yl)ethanes 2, easily prepared from the condensation of 1,2‐di(benzotriazol‐1‐yl)ethane‐1,2‐diol (1) and primary amides, were converted to 5‐acylaminooxazoles in good to moderate yields via intramolecular cyclization upon treatment with sodium hydride.
Acid catalyzed α‐alkylation of β‐aminothiophenes with aldehydes. synthesis of 2‐alkyl 3‐thiophenamines, bis(3‐amino‐2‐thienyl)‐methane derivatives and dithieno[3,2‐b:2′,3′‐e]pyridines
Authors: Berkaoui M'Hamed , Outurquin Francis , Paulmier Claude
Published: March 2009

The acid catalyzed reaction of 3‐thiophenamines with aldehydes in the presence of selenophenol as the reducing agent, gives 2‐alkyl‐3‐miophenamines. Without reduction, bis(3‐amino‐2‐thienyl)methane derivatives have been obtained and transformed into dithieno[3,2‐b:2′,3′‐e]pyridines by thermal and acidic treatment when the substrates are primary amines. These new tricyclic heterocycles can be synthesized in a one‐pot procedure from 3‐thiophenamine.
First asymmetric synthesis of 3‐alkoxycarbonyl‐2‐amino‐4‐aryl‐4H‐naphtho[1,2‐b]pyrans
Authors: Martín Nazario , Martínez‐Grau Angeles , Seoane Carlos , Marco José L. , Albert Armando , Cano Félix H.
Published: March 2009

The first asymmetric synthesis of 3‐alkoxycarbonyl‐2‐amino‐4‐aryl‐4H‐naphtho[1,2‐b]pyrans, by Michael addition of 1‐naphthol to chirally modified arylidenecyanoacetates 6 and 7, is described. Good yields and low diastereomeric excesses have been obtained in the 1,4‐conjugate additions. The absolute stereochemistry at C‐4 in major isomers of pyrans 8 and 9 has been assigned as 5 by X‐ray analysis of major pyran 8.
C‐5 functionalization of trisubstituted imidazoles with azodicarbonyl compounds
Authors: Yamazaki Chiji , Arima Hideshi , Udagawa Satoru
Published: March 2009

Certain 1,2,4‐trisubstituted imidazoles underwent electrophilic attack of azodicarbonyl compounds on the 5‐position to form 5‐(1,2‐dialkoxycarbonyl)hydrazino‐ and 5‐(4‐phenyl‐3,5‐dioxo‐1,2,4‐triazolidin‐1‐yl)imidazole derivatives in moderate to high yields. The reaction was highly susceptible to the nature and the substitution pattern of the substituents on the imidazole ring. Thus 1,4‐di‐ or 1,2,5‐trisubstitued imidazoles, and 2‐methylsulfinylimidazoles gave no reaction. Reductive cleavage of the tetrasubstituted imidazoles with zinc dust‐acid gave the 1‐ or 1,2‐cleaved product depending upon the reaction temperature, but the hydrazino moiety remained intact.
Novel hexahydrofuro[3,4‐b]‐2(1H)‐pyridones from 4‐aryl substituted 5‐alkoxycarbonyl‐6‐methyl‐3,4‐dihydropyridones
Authors: Morales Alhmed , Ochoa Estael , Suárez Margarita , Verdecia Yamila , González Leandro , Martín Nazario , Quinteiro Margarita , Seoane Carlos , Soto José L.
Published: March 2009

The title compounds 6 have been prepared in a one‐step procedure from the corresponding 4‐aryl substituted 5‐alkoxycarbonyl‐6‐methyl‐3,4‐dihydropyridones 4 in good yields. Quantum chemical calculations reveal a non‐planar molecule with a distorted dihydropyridone ring and two favoured conformations. The 13C nmr data and theoretical calculations support a strong push‐pull effect on the olefinic moiety.
Synthesis and electron impact mass spectra of 3‐substituted 2‐acylaminoindazoles
Authors: Kotali Antigoni , Harris Philip A.
Published: March 2009

3‐Substituted‐2‐acylaminoindazoles 2 were prepared via oxidative cyclization of o‐aminoaryl ketone acylhydrazones 1 with iodosobenzene diacetate. Their electron ionization mass spectra were recorded and in addition to the molecular ions show common fragmentation pathways corresponding to the [M‐N2]+, [M‐NHCOX]+ and [M‐COX]+ ions, with some influence on the skeletal fragmentation by different substituents.
Syntheses of 2‐(2‐arylethyl)‐1‐methylimidazoles
Authors: Shafiee A. , Morteza‐Semnani K. , Foroumadi A.
Published: March 2009

2‐(2‐Arylethyl)‐1‐memylimidazoles 3 could be prepared by different methods. The best method was the Wittig reaction of aryltriphenylphosphonium chloride 8 with 2‐formyl‐1‐methylimidazole to give compound 6. Reduction of compound 6 with Raney nickel gave compound 3.
1,3‐Dipolar cycloaddition reactions of isothiazol‐3(2H)‐ones with nitrile oxides. An unexpected site selectivity of the carbonyl bond of 5‐benzoyl‐isothiazol‐3(2H)‐one
Authors: Coutouli‐Argyropoulou E. , Anastasopoulos C.
Published: March 2009

2,6‐Dichlorobenzonitrile oxide (2a) reacts with isothiazolones 1a and 1b at the ethylenic double bond to give 4 via transformation of the primary cycloadducts 3. Mesitonitrile oxide (2b) adds preferentially to the carbonyl double bond of 1b yielding the monoadduct 5 and the bisadduct 6.
The preparation of 4‐substituted pyrylium salts and their use in dienal synthesis
Authors: Charoenying Patchanee , Hemming Karl , McKerrecher Darren , Taylor Richard J. K.
Published: March 2009

The unsubstituted pyrylium nucleus is shown to undergo reaction with cuprate or secondary Grignard organometallic reagents to give intermediate 4‐substituted pyrans which are converted into the corresponding 4‐substituted pyrylium salts (7 examples) in fair to good overall yield. The synthetic utility of the 4‐substituted pyrylium heterocycles is demonstrated by their reaction with organolithium reagents to give 3,5‐disubstituted dienals in a highly stereospecific manner (7 examples) via electrocyclic ring opening of the intermediate 2‐substituted pyrans.
Synthesis of 3‐substituted‐2,3,4,5‐tetrahydro‐1H‐naphth[1,2‐d]‐imidazole‐2,4,5‐triones and 1‐Substituted‐2,3,4,9‐tetrahydro‐1H‐naphth[2,3‐d]imidazole‐2,4,9‐triones
Authors: Bozzini Silvano , Nitti Patrizia , Pitacco Giuliana , Pizzioli Alessandro , Russo Claudio
Published: March 2009

Tricyclic compounds with an imidazolinone ring fused to 1,2‐ and 1,4‐naphtoquinones were synthesized by a reaction of 4‐amino‐1,2‐naphthoquinone and 2‐amino‐1,4‐naphthoquinone with electrophilic symmetric and non symmetric diazenes.
Synthesis and anti‐HIV‐1 activity of a series of 1‐(alkoxymethyl)‐5‐alkyl‐6‐(arylselenenyl)uracils and ‐2‐thiouracils
Authors: Kim Dae‐Kee , Kim Young‐Woo , Gam Jongsik , Kim Ganghyeok , Lim Jinsoo , Lee Namkyu , Kim Hun‐Taek , Kim Key H.
Published: March 2009

A series of 1‐(alkoxymethyl)‐5‐alkyl‐6‐(phenylselenenyl)uracils and ‐2‐thiouracils modified at the 3‐ and/or 5‐position of the C‐6 phenylselenenyl ring with methyl or fluoro substituent has been synthesized and tested for their ability to inhibit HIV‐1 replication. Lithiation of the acyclic uracil and 2‐thiouracil derivatives 11‐14 and 27‐32 with lithium diisopropylamide or lithium bis(trimethylsilyl)amide followed by reaction with an appropriate diaryl diselenide afforded 6‐arylselenenyl compounds 18‐26 after removal of the tert‐butyldimethylsilyl protecting group and 35‐47. Compounds 48‐54 were prepared from compounds 38‐44 by oxidative hydrolysis of the thione function. Of these compounds, 50 inhibited HIV‐1 replication in human T4 lymphoblastoid cells at a 50% effective concentration (EC50) of 0.0047 μM with a selectivity index of >42600.
Syntheses of 4‐(2‐hydroperoxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles, 4‐(2‐hydroxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles and the related compounds
Authors: Ouyang Jie , Nishino Hiroshi , Kurosawa Kazu
Published: March 2009

The reactions of 1,1‐disubstituted ethenes with 2,4‐pentanedione in the presence of manganese(III) acetate and atmospheric oxygen yielded 4‐acetyl‐6,6‐diaryl‐3‐methyl‐1,2‐dioxan‐3‐ols. The latter gave 4‐(2‐hydroperoxy‐2,2‐diarylemyl)‐3,5‐dimethylpyrazoles by the reaction with hydrazines in methanol‐acetic acid (1:1 v/v) at 50° in 15‐77% yields, or 4‐(2‐hydroxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles by the reaction with hydrazines in methanol in 2‐78% yields. The acid‐catalyzed reaction of 4‐(2‐hydroperoxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles yielded 4‐(aroylmethyl)‐3,5‐dimethylpyrazoles (15‐55%) and 4‐(2,2‐diarylethenyl)‐3,5‐dimethylpyrazoles (9‐29%).
Synthesis and reactivity of 2,3‐dihydro‐1H‐pyrrolo[1,2‐a]indole derivatives, analogs of the FR900482 and mitomycin C active intermediates
Authors: Zhang Weihong , Locurcio Michael , Lin Chuan‐Chuan , Jimenez Leslie S.
Published: March 2009

A series of 2,3‐dihydro‐1H‐pyrrolo[1,2‐a]indoles were prepared as analogs of the active intermediates of the natural products, mitomycin C and FR900482, and their reactions with various nucleophiles were studied.
Versatile synthesis of 6‐substituted 8‐deazapteridine‐2,4‐diamines. Formal total synthesis of 8,10‐dideazaminopterin
Authors: Troschütz Reinhard , Karger Alexander
Published: March 2009

A new synthesis of 4‐amino‐4‐deoxy‐8,10‐dideazapteroic acid (11d) and 6‐substituted and 5,6‐anellated 8‐deazapteridine‐2,4‐diamines, 10a, 10d, 25, is described. Starting from keteneaminals 1 or 12 and enaminones 4 or β‐aminoketone 17 the title compounds can be prepared via functional group transformation of 2‐amino‐3‐nitropyridines 5 or nicotinate 13a yielding 3‐amino‐α‐picolinonitriles 9 which are cyclocondensed with guanidine.
New 4‐(benzotriazol‐1‐yl)‐1,2,3‐triazole derivatives
Authors: Biagi Gialiana , Giorgi Irene , Livi Oreste , Scartoni Valerio , Velo Silvia , Barili Pier Luigi
Published: March 2009

A new 4‐(benzotriazol‐1‐yl)‐1,2,3‐triazole structure was obtained by the diazotization reaction of either of 1‐(2‐aminophenyl)‐4‐carboxamido‐5‐amino‐1H‐1,2,3‐triazole (1c) or of the corresponding Dimroth isomer 1d. It underwent some common reactions to evaluate its chemical behaviour and structure. An analogous reaction sequence was carried out from the 2‐nitro‐4‐methylphenyl azide, to assign the structure to the nitro derivatives prepared. The structure of the new compounds prepared was confirmed by chemical and spectroscopic methods.
A new synthesis of aryl substituted quinazolin‐4(1H)‐ones
Authors: Roth Gary A. , Tai Jimmy J.
Published: March 2009

Treatment of a variety of substituted 2‐aminobenzonitriles with formic acid under strong acid catalysis provides the corresponding quinazolin‐4(1H)‐ones in good yield. A potential reaction pathway is described.
Syntheses of 2‐spiroindoles and pyrrolof[1,2‐a]indoles
Authors: Malapel‐Andrieu B. , Mérour J.‐Y.
Published: March 2009

C‐alkylated products obtained from methyl 3‐hydroxyindole‐2‐carboxylate afford either spiro compounds, such as an indolic analogue of nitramine, or tricyclic products with a pyrrolo[1,2‐a]indole framework. Di‐C‐alkylated derivatives give access to tetracyclic compounds.
Thermal Cyclization of 2‐Acyl‐1‐azido‐3‐phenalenones to Phenaleno[1,2‐c]isoxazol‐7‐ones
Authors: Stadlbauer Wolfgang , Fischer Michaela
Published: March 2009

1‐Azido‐3‐phenalenones 5 with acyl substituents in position 2, obtained by acylation and azidation of 1‐hydroxy‐3‐phenalenones 1, cyclized by thermolysis to give phenaleno[1,2‐c]isoxazol‐7‐ones 9. The thermolysis conditions were studied by differential scanning calorimetry.
On corrole chemistry. An isomerization study and oxidative cleavage of the corrole macroring to a biliverdin structure
Authors: Tardieux Catherine , Gros Claude P. , Guilard Roger
Published: March 2009

In the present paper, we report the synthesis of free 5‐ and 10‐monophenylcorroles, 4 and 3 respectively as well as the first example of molecular oxygen oxidation of the corrole macrocycle identified as an open chain tetrapyrrole (biliverdin) structure 7. Reaction of 1 and 2 in acetic acid leads to a mixture of two a,c‐biladienes 3b and 4b and therefore to a mixture of two corrole isomers 3 and 4. Reaction of 1 and 2 in trifluoroacetic acid leads only to the symmetrical corrole isomer 3 in 41% yield.
Structural characterization of components of a mixture‐characterization of a facile oxidation product of cryptolepinone in situ
Authors: Hadden Chad E. , Duholke Wayne K. , Guido Jane E. , Robins Russell H. , Martin Gary E. , Sharaf Maged H. M. , Schiff Paul L.
Published: March 2009

The nmr analysis of a mixture of cryptolepinone and it's 5(N)‐oxide in a 1.5:1 ratio is discussed. The differentiation of the resonances of the two similar compounds, and elucidation of the unknown 5(N)‐oxide relied primarily on IDR‐GHSQC‐TOCSY data in conjunction with ROESY, GHSQC, and GHMBC experiments.
Aminopyrazoles and their conjugated acids. An X‐ray study of 3,5‐dimethyl‐4‐aminopyrazole and the Picrate of 3(5)‐aminopyrazole
Authors: Infantes Lourdes , Foces‐Foces Concepción , Claramunt Rosa María , López Concepción , Eiguero José
Published: March 2009

The crystal structure determination of 3,5‐dimethyl‐4‐aminopyrazole (3) and of 3(5)‐aminopyrazolium picrate salt (5a) have been undertaken. The packing in 3 is characterized by the formation of sheets in which the N‐H of the pyrazole and one H atom of the amino group are involved. The remaining HB donor interconnects sheets. In 5a, the anions and the cations are linked by a two‐dimensional network of hydrogen bonds in the ab plane. Each N‐H and C‐H in the cation are involved in hydrogen interactions with the O atoms of the anion. Ab initio molecular orbital methods at the HF and B3LYP levels using a 6–31G** basis set have been carried out to compare the relative stability of the tautomeric forms of the 3(5)‐aminopyrazolium and 4‐aminopyrazolium cations.
Reductive ring cleavage of 1‐alkyl‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinones with raney‐nickel alloy. Synthesis of N‐benzoyl‐3‐alkylamino‐3‐phenylalanine amides from rel‐(4R,5R)‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinone
Authors: Zupančič Silvo , Svete Jurij , Stanovnik Branko
Published: March 2009

rel‐(4R,5R)‐4‐Benzoylamino‐5‐phenyl‐3‐pyrazolidinone (1) was alkylated at position 1 with carbonyl compounds 2a‐g. The corresponding rel‐(4R,5R)‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinone‐1‐azomethine imines 3a‐g, were treated with sodium borohydride to give rel‐(4R,5R)‐1‐alkyl‐4‐benzoylamino‐5‐phenyl‐3‐pyrazolidinones 4a‐g. Reduction of pyrazolidinones 4a‐g with Raney‐nickel alloy in methanolic potassium hydroxide furnished rel‐(4R,5R)‐N‐benzoyl‐3‐alkylamino‐3‐phenylalanine amides 5a‐f.
Chalcogenopyranones from disodium chalcogenide additions to 1,4‐pentadiyn‐3‐ones. The role of enol ethers as intermediates
Authors: Leonard Kristi , Nelen Marina , Raghu Madhavi , Detty Michael R.
Published: March 2009

Enol ethers 9 are formed as a mixture of E‐ and Z‐isomers from the addition of ethanol to 1,4‐pentadiyn‐3‐ones 2 in sodium ethoxide/ethanol. The enol ethers react with disodium chalcogenides to give the corresponding 2,6‐disubstituted chalcogenopyranones 1 bearing alkyl, aryl, or heteroaryl substituents in high yield as the only heterocyclic product of reaction. Diynones 2 react with disodium chalcogenides to give mixtures of products in which the chalcogenopyranones 1 are minor components and the dihydrochalcogenophenes 3 are the major products. The addition of hydrogen sulfide to diynone 2b in ethanol gives a product mixture nearly identical to that observed for the addition of disodium sulfide in sodium ethoxide in ethanol to 2b. Intermediates for the addition of hydrogen chalcogenides and disodium chalcogenides to both 2 and 9 are described, which lead to the heterocyclic products.
EIMS study of new isomeric N‐substituted hydrazones of 2‐(3‐ and 4‐)‐pyridinecarboxaldehydes
Authors: Wyrzykiewicz E. , Prukała D.
Published: March 2009

EI induced mass spectral fragmentations of twelve new hydrazones of 2‐(3‐ and 4‐)‐pyridinecarboxaldehydes and hydrazides of (E)‐stilbenyloxyacetic acid as well as N‐(E)‐stilbenyloxyalkylcarbonyl substituted amino acids were investigated. Fragmentations pathways are proposed on the basis of accurate mass and B/E linked scan spectra measurements. The correlation between the intensities of M+. and the selected fragment ions of these compounds is discussed. The data obtained create the basis for distinguishing isomers.
Synthesis of 3‐(4‐Oxo‐4H‐quinolizinyl‐3) and 3‐(4‐Oxo‐4H‐pyridino[1,2‐a]pyrimidinyl‐3) substituted lactic acid derivatives
Authors: Škof Marko , Svete Jurij , Stanovnik Branko
Published: March 2009

A one‐step ‘ring switching’ transformation of (S)‐3‐[(dimethylamino)methylidene]‐5‐(methoxycarbonyl)tetrahydrofuran‐2‐one (4) with 2‐pyridineacetic acid derivatives (5–7) and 2‐aminopyridines (8, 9) afforded the corresponding 3‐(4‐oxo‐4H‐quinolizinyl‐3)‐ (15–17) and 3‐(4‐oxo‐4H‐pyridino[1,2‐a]pyrimidinyl‐3)‐2‐hydroxypropanoates (18, 19), respectively.
Transformation of 6‐methylthiopyrimidines. Preparation of new pyrimidine derivatives and fused azolopyrimidines
Authors: Cocco Maria Teresa , Congiu Cenzo , Onnis Valentina
Published: March 2009

2,4‐Diamino‐6‐methylthiopyrimidines 1 reacted with sodium methoxyde and benzylamine to give the corresponding 6‐methoxypyrimidine and 6‐benzylaminopyrimidine derivatives 2 and 4 respectively. The reaction of 1 with hydrazine hydrate, in ethanol, gave 6‐hydrazino derivatives 6. However, by treating pyrimidines 1 in boiling hydrazine hydrate 3,6‐diamino‐4‐hydrazino‐1H‐pyrazolo[3,4‐d]pyrimidine 5 was obtained. The 6‐hydrazinopyrimidines 6 could be converted into the pyrazolo[3,4‐d], triazolo[4,3‐c] and tetrazolo‐[1,5‐c]pyrimidines 7, 8 and 9 by the action of heating, trimethyl orthoformate and nitrous acid, respectively.
A comparison of crystallographic and NMR data for thieno[2,3‐b:4,5‐b′]dipyridine and its monohydroperchlorate salt
Authors: Klemm Leroy H. , Weakley Timothy J. R. , Yoon Myungok , Clegg Robert S.
Published: March 2009

X‐ray crystallographic studies of thieno[2,3‐b:4,5‐b′]dipyridine (1) and its monohydroperchlorate salt (1a) show that 1 is protonated at N1 in ring A and not at N6 in ring C. In each compound individual rings are planar, but there is a small dihedral angle‐of‐twist between the A and C rings. On going from 1 to 1a the largest changes in bond angles and bond lengths occur in ring A. 1H and l3C nmr spectra of 1 plus the 13C nmr spectrum of 1a are reported.
Synthesis and characterization of some heterocyclic derivatives by cyclization of carbohydrate thiosemicarbazone — part II
Authors: Alho M. A. Martins , D'Accorso N. B.
Published: March 2009

The syntheses of 2,3‐dihydro‐1,3,4‐thiadiazoles and 1,3,4‐thiadiazoles from 1,2‐O‐isopropylidene‐α‐D‐xylo‐1,5‐pentadialdo‐1,4‐furanose thiosemicarbazone are described. The new compounds as well as the intermediate products are physically and spectroscopically characterized. We discuss a possible mechanistic pathway for heterocyclization in this particular substrate, using computational calculation.
Diastereoselective alkylation of acetoacetates of chiral inductors. Synthetic applications
Authors: Gálvez N. , Moreno‐Mañas M. , Sebastián R. M. , Serra N. , Trepat E. , Vallribera A. , Molins E.
Published: March 2009

Diastereoselective alkylations of acetoacetates of chiral inductors are reviewed. The formed products are starting materials for the preparation of enantiomerically pure amino acids, 4,4‐disub‐stituted 2‐pyrazolin‐5‐ones, and of oxazoles and pyrazoles incorporating the chiral inductors.
Preparation of substituted 1,2‐Dihydro‐3H‐pyrazol‐3‐ones from polylithiated 2′‐phenylphenylacetohydrazides and aromatic esters
Authors: Downs Jennifer R. , Pastine Stefan J. , Townsend Jessica D. , Greer Heather A. , Kelley Wayne , Schady Deborah A. , Mcconaughy Teresa Lentz , Metz Clyde R. , Beam Charles F. , Almquist Catharine D. , Pennington William T. , Walsch Rosa D. Bailey
Published: March 2009

Several 2′‐phenylphenylacetohydrazides were polylithiated with excess lithium diisopropylamide, and the resulting intermediates were condensed with several aromatic esters to afford C‐acylated intermediates that were not usually isolated, but acid cyclized directly to 1,4,5‐trisubstituted, 1,2‐dihydro‐3H‐pyrazol‐3‐ones.
Synthesis and biological study of 6‐polyhydroxyalkylpteridines
Authors: López M. Dolores , Quijano M. Luisa , Sánchez Adolfo , Nogueras Manuel , Low John N.
Published: March 2009

6‐Polyhydroxyalkylpteridines are synthesised by oxidation of the corresponding pyrano[3,2‐g]pteridines, the latter ones having been obtained by condensation between 5,6‐diaminopyrimidines 1a,b and phenylhydra‐zones 2a‐e. The relative configuration at the chiral centers of the pyrano[3,2‐g]pteridines has been determined by nmr study and X‐ray analysis. The anti‐AIDS activity of several of these compounds has been tested.
A synthesis of new pyrrolo[3,2‐c]quinolines
Authors: Dudouit Fabienne , Houssin Raymond , Hénichart Jean‐Pierre
Published: March 2009

A synthesis of pyrrolo[3,2‐c]quinolines substituted in the 7‐ and 8‐ positions by methoxy groups and in the 3‐ position by an amido group is described. The structures were designed to have a crescent shape, a planar fused cyclic moiety with two ortho methoxy groups and ionisable amino or amidinic group at pH 7.
Synthesis of 4‐amino‐3,5‐dinitro‐1H‐pyrazole using vicarious nucleophilic substitution of hydrogen
Authors: Schmidt Robert D. , Lee Gregory S. , Pagoria Philip F. , Mitchell Alexander R. , Gilardi Richard
Published: March 2009

A novel synthesis of the title compound was achieved by direct animation using Vicarious Nucleophilic Substitution (VNS) methodology. Reaction of 1,1,1‐trimethylhydrazinium iodide with 3,5‐dinitropyrazole in DMSO produces 4‐amino‐3,5‐dinitro‐1H‐pyrazole as a 1:1 crystal solvate with DMSO. Recrystallization from water yields the monohydrated crystal. Recrystallization of the monohydrate from butyl acetate yields the compound in pure form.