bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared study of hydrogen bonds involving N‐heterocyclic bases and phenols
Authors: Goethals Muriel , Zeegers‐Huyskens Thérese , Czarnik‐Matusewicz Boguslawa 
Published: March 2009

AbstractThe hydrogen bond complexes between phenols and N‐heteroaromatic bases 2,4,6‐tri(2‐pyridyl)‐1,3,5‐triazine, 2,2′,2′‐terpyridine, quinoxaline, pyrido[2,3‐b]pyrazine, pyzazino [2,3f]quinoxaline and 5‐nitrozphenanthroline are investigated by infrared spectroscopy in 1,2‐dichloroethane. The stability constants of the complexes involving N‐heteroaromatic bases characterized by tow vicinal nitrogen atoms having lone pairs pointing to each other are higher than predicted from their basicity. Possible differences between protonation and hydrogen bond formation are discussed. Nheteroaromatic bases such as tri(2‐pyridyl)‐1,3,5‐triazine or phenanthrolines cannot be considered as proton sponges but their behaviour is intermediate between that of the classical heteroaromatic bases and the proton sponges.
A convenient synthesis of the novel 5H‐thieno[2,3‐e]‐4,1,2‐oxathiazepine ring systemviaan alkoxycarbenium ion intermediate
Authors: Dantanarayana Anura P. , Dupre Brian , May Jesse A. , Lynch Vincent M. 
Published: March 2009

Abstract3‐(Methoxymethoxymethyl)‐2‐thiophenesulfonamides and 3‐hydroxymethyl‐N‐methoxymethyl‐2‐thiophenesulfonamides have been shown to undergo cyclization when treated under anhydrous acidic conditions to provide the novel 2,3‐dihydro‐5H‐thieno[2,3‐e]‐4,1,2‐oxathiazepine ring system. Incorporation of a primary sulfonamide group into position seven of the molecule provided compounds which inhibit human carbonic anhydrase II.
Haloacetylated enol ethers. 11. Synthesis of 1‐methyl‐ and 1‐phenyl pyrazole‐3(5)‐ethyl esters. A one‐pot procedure
Authors: Martins Marcos A. P. , Freitag Rogério A. , Da Rosa Adriano , Flores Alex F. C. , Zanatta Nilo , Bonacorso Helio G. 
Published: March 2009

AbstractA one‐pot synthesis of 1‐methyl‐ and 1‐phenylpyrazole‐3(5)‐ethyl esters 2,3a‐e by the cyclocondensation of β‐alkoxyvinyl trichloromethyl ketones 1a‐e with methyl and phenyl hydrazine hydrochloride under mild conditions, is reported. A study using compounds 1a‐e with different substituents proved that these are versatile building blocks for the synthesis of pyrazole derivatives, having a 3(5)‐ethoxycarbonyl substituent in good yields (60–89%). The hydrazine and β‐alkoxyvinyl trichloromethyl ketone substituent effects on the reaction regiochemistry on the formation of the 1,3‐ and 1,5‐isomer were observed.
Synthesis of β‐butylsulfanyl α‐oligothiophenes from 3‐butylsulfanyl‐2,2′‐bithiophene
Authors: Iarossi Dario , Mucci Adele , Schenetti Luisa , Sodini Valerio 
Published: March 2009

Abstractβ‐Butylsulfanyl tetra‐, sexa‐, and octathiophenes were synthesized by oxidative coupling with iron(III) chloride from 3‐butylsulfanyl‐2,2′‐bithiophene. Tetrathiophene was also generated through coupling reac tions. The nmr characterization of oligomers is reported and discussed.
Retro‐ene reaction. V. Functionalization of 4,5‐dihalopyridazin‐6‐ones using 1‐hydroxymethyl‐4,5‐dihalopyridazin‐6‐ones as 1–0, 3‐n, 5–0 ene‐adducts
Authors: Chung Hyun‐A , Kang Young‐Jin , Chung Joo‐Wha , Cho Su‐Dong , Yoon Yong‐Jin 
Published: March 2009

AbstractFunctionalization of 1‐hydroxymethyl‐4,5‐dihalopyridazin‐6‐ones via a retro‐ene reaction with some nucleophiles gave regioselectively only 5‐halo‐4‐substitutedpyridazin‐6‐ones.
Synthesis of pyrazoles and condensed pyrazoles
Authors: Makino Kenzi , Kim Ho Sik , Kurasawa Yoshihisa 
Published: March 2009

AbstractThis review introduces the synthesis of various pyrazoles reported by us and some other research groups during 1989–1998. Some of papers in this review deal with the development of potent pyrazoles or with the synthesis of potential pyrazoles aiming at agrochemicals and/or drugs.
Complete spectroscopic structural characterization of novobiocin, isonovobiocin, decarbamylnovobiocin, 2″‐(o‐Carbamyl)novobiocin, and novobiocin‐2″,3″‐carbonate
Authors: Crow Frank W. , Duholke Wayne K. , Hadden Chad E. , Smith Richard F. , Thamann Thomas J. , Kaluzny Brian D. , Hahn David A. , Mallory Christopher S. , Farley Kathleen A. , Martin Gary E. 
Published: March 2009

AbstractThe rigorous structural characterization of novobiocin, is reported using mass spectrometric, infrared and nmr spectroscopic analysis. Complete nmr assignments are reported. Previous reports in the literature had left some quaternary carbon resonances unassigned. Isonovobiocin and decarbamylnovobiocin, although known in the literature for a number of years, have never been completely characterized. Mass spectrometric fragmentation pathways and complete 1H and 13C nmr assignments are reported for these congeners for the first time. The mass spectral fragmentation pathway and nmr assignments are also reported for 2″‐(O‐carbamyl)novobiocin although the nmr assignments at lower field were reported previously. The structural characterization of novobiocin‐2″,3″‐carbonate observed in the Test Assay procedure used for Novobiocin is reported for the first time.
Synthesis and structure of novel 4‐arylhexahydro‐1H,3H‐pyrido[1,2‐c]pyrimidine derivatives
Authors: Herold Franciszek , Helbin Ewa , Król Marek , Wolska Irena , Kleps Jerzy 
Published: March 2009

AbstractA series of new 4‐aryl‐hexahydro‐1H,3H‐pyrido[1,2‐c]pyrirnidine‐1,3‐dione derivatives4a‐kwere prepared by catalytic hydrogenation of 4‐aryl‐1H,2H‐pyrido[1,2‐c]pyrirnidine‐1,3‐diones3a‐k.The structures of compounds were determined by1H and13C nmr spectroscopy in solution. Steric hindrance caused twisting of the phenyl ring with respect to the pyridopyrimidine system, the effect was confirmed by X‐ray diffraction.
Cyclization of 2‐ and 3‐indolylthiobenzoic, phenylacetic and nicotinic acids and esters to novel indole‐containing tetracyclic ring systems
Authors: Hamel Pierre , Girard Mario , Tsou Nancy N. 
Published: March 2009

AbstractA series of 2‐ and 3‐indolylthio benzoic, phenylacetic and nicotinic acids or esters were cyclized under dehydrative conditions affording several tetracyclic indole‐containing ketones, several of which constitute the first reported examples of novel ring systems, such as the [1]benzothiepino[2,3‐b] and [3,2‐b]indole and the pyrido[3′2′:5,6] and [3′4′:5,6]thiopyrano[2,3‐b] and [3,2‐b]indole as well as the [3′2′:5,6] and [3′4′:5,6][1,3]thiazino[3,2‐a]indole ring systems.
Synthesis of methyl 3‐amino‐4‐aryl(or methyl)sulfonyl‐2‐thiophenecarboxylates from 3‐alkoxy‐2‐aryl(or methyl)‐sulfonylacrylonitriles
Authors: Stephens Chad E. , Price Matthew B. , Sowell J. Walter 
Published: March 2009

AbstractThe synthesis of a series of methyl 3‐amino‐4‐aryl(or methyl)sulfonylthiophene‐2‐carboxylates by reaction of 3‐alkoxy‐2‐aryI(or methyl)sulfonylacrylonitriles with methyl thioglycolate in the presence of triethylamine is described. Hydrolysis/decarboxylation of the ester at the 2‐position and acylation of the resulting amine represents a convenient route to 4‐arylsulfonyl‐3‐carboxamidothiophenes. Attempted acylation of a title aminothiophene under standard conditions was unsuccessful.
A quantitative study of substituent effects on oxidative cyclization of some 2‐aryl‐substituted aldehyde thiosemicarbazones induced by ferric chloride and cupric perchlorate
Authors: Noto Renato , Meo Paolo Lo , Gruttadauria Michelangelo , Werber Giuseppe 
Published: March 2009

AbstractAs a development of our previous work, we performed a kinetic study of the oxidative cyclization reaction of some 2,4‐diaryl‐substituted aldehyde thiosemicarbazones 1a‐n induced by ferric chloride and by cupric perchlorate. The results of cyclization of 1a‐n were compared to those of the corresponding 2‐methyl derivatives. The kinetic data were analyzed by means of the Hammett's equation.
Acyliminium ion‐olefin cyclization leading to isoindolo[2,1‐a]quinoline derivatives
Authors: Pigeon Pascal , Othman Mohamed , Netchitaïlo Pierre , Decroix Bernard 
Published: March 2009

AbstractIsoindolo[2,1‐a]quinolines 10, 11, 12 were synthesized from hydroxylactams 8 or 9 via an N‐acyliminium ion‐π‐olefin nucleophile cyclization reaction.
Polycyclic systems: Synthesis of isoindolo[2,1‐b]‐pyrrolo[1,2‐d][2,4]benzodiazocine and isoindolo‐[1,2‐d]pyrrolo[1,2‐a] [1,5]benzodiazocine
Authors: Othman Mohamed , Pigeon Pascal , Decroix Bernard 
Published: March 2009

AbstractThe synthesis of isoindolo[2,1‐b]pyrrolo[1,2‐d][2,4]benzodiazocine 7 and isoindolo[1,2‐d]pyrrolo[1,2‐a]‐[1,5]benzodiazocine 13 are described starting from 2‐(2‐methoxycarbonyl)benzylphthalimide 1a and ethyl α‐bromohomophthalate 9 respectively.
A convenient preparation of 1,3‐disubstituted dihydro‐2,4‐(1H,3H)pyrimidinediones
Authors: Deck L. M. , Papadopoulos E. P. 
Published: March 2009

AbstractThe ureas 3 which are obtained from 3‐(benzylamino)propanenitrile (1) and various isocyanates (2) cyclize readily upon heating in ethanol, in the presence of hydrochloric acid, to form 3‐substituted 1‐benzyldihydro‐2,4‐(1H,3H)pyrimidinediones (11) in good yield.
Syntheses, crystal structures, and metal ion complexation studies of novel diaza‐18‐crown‐6 ligands containing aromatic thiol‐derived side arms
Authors: Su Ning , Bradshaw Jerald S. , Xue Guoping , Dalley N. Kent , Zhang Xian X. , Savage Paul B. , Krakowiak Krzysztof E. , Izatt Reed M. 
Published: March 2009

AbstractThe Mannich aminomethylation reaction of aromatic thiols has been used to produce diaza‐18‐crown‐6 ligands containing thiol‐derived side arms. Thiophenols were attached to the azacrown through N‐CH2‐S linkages even in the presence of hydroxy or acetamido groups. Heteroaromatic thiols containing N=C‐SH (or NH‐C=S) structural fragments were attached to diaza‐18‐crown‐6 by N‐CH2‐N linkages with the thiol becoming a thione function. X‐ray crystal structural analyses show the N‐CH2‐S and N‐CH2‐N linkages for some of the new macrocyclic compounds. Interactions of four of the new diaza‐18‐crown‐6 ligands with Na+, K+, Ba2+, Ag+, Zn2+, Cd2+, Ni2+, and Cu2+ were evaluated by calorimetric titration at 25° in methanol. The results show that these ligands form stable complexes with many of the metal ions studied.
Synthesis and transformations of stereoisomeric ethyl 2‐isothiocyanato‐1‐cyclopentanecarboxylatesm
Authors: Palkó Márta , Fülöp Ferenc , Evanics Ferenc , Bernáth Gábor 
Published: March 2009

AbstractEthyl vis‐ and trans‐2‐isothiocyanato‐1‐cyclopentanecarboxylates 2 and 7 were prepared by the reaction of the corresponding alicyclic ethyl 2‐amino‐1‐carboxylates and thiophosgene. The cis‐isothiocyanato compound 2 underwent ring closure with amines in one or two steps, resulting in 3‐substituted‐cis‐2‐thioxocyclopenta[d]pyrimidin‐4‐ones 3a‐g. The trans isomer 7 failed to cyclize, but gave carboxamide 8a,b or thiourea ester derivatives 9a,b.
New lipophilic crown ethers with intraannular carboxylic acid groups: Synthesis and alkali metal cation extraction
Authors: Bratton Larry D. , Huh Hwang , Bartsch Richard A. 
Published: March 2009

AbstractA six‐step synthetic route to four lipophilic crown ethers with intraannular carboxylic acid groups and ring sizes of 15‐crown‐4, 18‐crown‐5, 21‐crown‐6 and 24‐crown‐7 is described. Eight new polyether compounds that bear inward‐facing bromo and formate ester substituents are prepared as synthetic intermediates. Selectivities and efficiencies of the four new lipophilic crown ether carboxylic acids in competitive alkali metal cation extraction from aqueous solutions into chloroform are evaluated.
New isomeric N‐substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes and methyl‐3‐pyridylketone
Authors: Wyrzykiewicz Elzbieta , Blaszczyk Alfred 
Published: March 2009

AbstractTwelve compounds unknown in the literature N‐(E)‐2‐stilbenyloxymethylenecarbonyl substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes, as well as methyl‐3‐pyridylketone have been prepared. The stereochemical behavior of these compounds in dimethyl‐d6 sulfoxide solution has been studied by 1H NMR technique. The E geometrical isomers and cis/trans amide conformers have been found for N‐substituted hydrazones 1–12. EI induced mass spectral fragmentation of these compounds were also investigated. The data obtained create the basis for distinguishing isomers.
Synthesis of lariat ether carboxylic acids based on dibenzo‐16‐crown‐5
Authors: Bartsch Richard A. , Cowey Charles L. , Elshani Sadik , Goo Mi‐Ja , Huber Vincent J. , Ivy Sheryl N. , Johnson Russell J. , Kim Jong Seung , Luboch Elzbieta , Mcdonough Joseph A. , Pugia Michael J. , Son Byungki , Zhao Qiang 
Published: March 2009

AbstractSynthetic routes to forty‐seven dibenzo‐16‐crown‐5 compounds with pendant carboxylic acid groups are reported. When taken together with previously described lariat ether carboxylic acids, these new compounds provide several series with systematic structural variations including changes in the identity and attachment site(s) of one or more lipophilic groups and the length of the spacer that connects the carboxylic acid group to the polyether framework.
Synthesis of 4‐(7‐diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO): A highly sensitive fluorescent derivatization reagent for alcohols in high‐performance liquid chromatography
Authors: Takechi Haruko , Goto Yasuo , Takahashi Hajime , Machida Minoru 
Published: March 2009

Abstract4‐(7‐Diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO) was synthesized as a new fluorescent derivatization reagent for alcohols for use in high‐performance liquid chromatography (hplc). Saturated alcohols (C6‐C22) were derivatized in good yields into the corresponding fluorescent DACB‐carbamic esters by treating with DACB‐NCO. The DACB‐carbamic esters of these alcohols were clearly separated on a reversed‐phase hplc column (Inertsil ODS‐2, mobile phase: methanol‐water, excitation wavelength 402 nm; emission wavelength 488 nm). The detection limit (S/N = 3) of cetyl alcohol, as a test compound, was 5 fmol/10 μl.
The chemistry of the highly reactive 2,6‐bis(bromomethyl)‐4‐pyrone
Authors: Löwe Werner , Brätter Stefanie A. , Weber Manuela , Luger Peter , Buddrus Joachim 
Published: March 2009

AbstractUnder basic conditions 2,6‐bis(bromomethyl)‐4‐pyrone 8 reacts with tetraethylene glycol to yield the unexpected macrocycle 9, which is related to the antibiotic Kjellmanianone 10. We propose that this ring transformation proceeds via the cyclopropyl intermediate d (Scheme 2), which undergoes a ring opening reaction comparable to the Favorskii rearrangement. Also, 8 reacts with methanol/sodium methoxide to yield the 3(2H)‐furanone derivative 11, the formation of which is suggested to proceed via the intermediate k with a carbenium‐oxonium‐ion subunit (Scheme 3). The structure of the 3(2H)‐furanone derivative was confirmed by X‐ray analysis.
A new dimerization reaction producing 2‐amino‐9‐oxopyrrolo‐[2,1‐b]quinazoline‐1‐carbonitriles and analogous pyrrolo‐[1,2‐a]thieno[3,2‐d] pyrimidinecar bonitriles
Authors: Gütschow Michael , Powers James C. 
Published: March 2009

AbstractA series of 2‐alkylthio‐4‐oxo‐3‐quinazolineacetonitriles 4 and 2‐alkylthio‐4‐oxothieno[3,2‐d]pyrimidine‐3‐acetonitriles 8 was prepared. Upon treatment with sodium hydride, compounds 4 and 8 react to give 2‐amino‐4,9‐dihydro‐9‐oxopyrrolo[2,1‐b]quinazoline‐1‐carbonitriles 9 and 6‐amino‐4,9‐dihydro‐9‐oxopyrrolo[1,2‐a]thieno[3,2‐d]pyrimidine‐7‐carbonitriles 10, respectively. The transformation of compounds 4 and 8 to the tricyclic aminonitriles 9 and 10 involves a dimerization step followed by a pyrrole cyclization. The tert‐butyl ester derivatives 4d and 8d upon treatment with sodium hydride underwent a Thorpe‐Ziegler cyclization to provide enaminoesters of fused 1,3‐thiazines (16 and 17, respectively) as major products.
A facile synthesis of some thieno/furo‐[2,3‐d]pyrimidine‐2‐yl‐thioacetic acid derivatives
Authors: Demirayak S̨Eref , Mohsen Usama Abu 
Published: March 2009

AbstractThe reaction of 2‐(α‐chloroacetamido)‐3‐cyano‐4,5‐disubstituted thiophenes/furanes with ammonium thiocyanate in methanol or ethanol afforded methyl or ethyl (4‐amino‐5,6‐disubstituted thieno/furo[2,3‐d]‐pyrimidine‐2‐yl)thioacetates in good yields.
Preparation of novel 2‐(benzo[b]furan‐2‐yl)‐1H‐imidazolines for photoaffinity labelling and affinity isolation of imidazoline binding
Authors: Clews Proteins J. , Ramsden Christopher A. , Morgan Noel G. 
Published: March 2009

AbstractThe preparations of 5‐aminoefaroxan 8 and 5‐azidoefaroxan 9, which retain the capacity to stimulate insulin secretion via the putative I3 imidazoline receptor and are useful biological tools for affinity chromatography studies and photoaffinity labelling studies of imidazoline binding proteins, are described
Structure elucidation, conformational analysis and thermal effects on membrane bilayers of an antimicrobial myricetin ether derivative
Authors: Demetzos C. , Angelopoulou D. , Kolocouris A. , Daliani I. , Mavromoustakos T. 
Published: March 2009

AbstractThe membrane perturbing 3,7,4′,5′‐tetramethyl ether of myricetin 1 was isolated from Cistus monspelien‐sis L. Its structure was elucidated and its conformational properties were explored using a combination of 2D NMR spectroscopy and computational chemistry. The obtained results showed that compound 1 adopts four enantiomeric pairs of low energy conformers characterized: (a) by an aromatic ring B twisted through rotation about C2‐C1′ bond from the rigid isoflavone ring; (b) a 4′‐O‐CH3 bond oriented out of the plane with equal probability upwards or downwards the phenyl ring B, while all the other O‐CH3 bonds are oriented in the plane of the aryl ring. Two of these enantiomeric pairs are lowest in energy. These possible bioactive con‐formers are possibly stabilized by van Der Waals interactions. The 3′,5‐diacetyl derivative 2 of compound 1 was synthesized and its structure elucidation was achieved based on the chemical shift assignment of the parent compound 1. The Differential Scanning Calorimetry (DSC) results revealed that the degree of the thermal effects exerted by the flavonoids at dipalmitoylphosphatidyl choline (DPPC) bilayers followed the order 1 > 2 > myricetin. Their antimicrobial activity against Gram positive bacteria followed the same order.
2‐Arylethenyl‐2′‐arylethynyl sulfones: A potential source for some spiroheterocycles
Authors: Reddy Dandu Bhaskar , Babu Nalla Reddy Chandrasekhar , Padmavathi Venkatapuram 
Published: March 2009

AbstractThe double Michael addition of dimethyl malonate to 2‐arylethenyl‐2′‐arylethynyl sulfones (3) resulted in 3,5‐diaryl‐5,6‐dihydro‐4,4‐dimethoxycarbonyl‐1‐thiin‐1,1‐dioxides (4). The latter on cyclocondensation with urea / thiourea / hydrazine hydrate / hydroxylamine hydrochloride gave spiroheterocycles.
Bicyclic [b]‐heteroannulated pyridazine derivatives. 9. cyclization reactions of 4,4‐dimethyl‐ and 4‐phenyltetrahydropyridazine‐3,6‐dione 3‐hydrazones with esters of keto dicarboxylic acids
Authors: Wejroch Krystyna , Lange Jerzy , Kielak Anna , Karolak‐Wojciechowska Janina , Sośnicki Jacek , Jagodziński Tadeusz 
Published: March 2009

AbstractBis(ethoxycarbonyl)alkylidene derivatives 4 and 5 of the respective title hydrazones were obtained in the reactions with diethyl oxomalonate, diethyl oxosuccinate, diethyl 2‐oxoglutarate, and diethyl oxalo‐propionate as mixtures of geometric isomers with high predominance of one of them. On heating at 160‐200° without any solvent or on refluxing in ethanol 4 cyclized to yield the corresponding pyri‐dazino[6, 1‐c]triazines 6, whereas heating of 5 gave, depending on the chain length, the corresponding pyra‐zolylpyridazines 8b and 8d or the pyridazinylpyridazine 8c. X‐ray analysis was used to determine the structures of 6 and 8; the unit cell of 6c was found to accommodate 16 molecules representing four conforma‐tional varieties. The different behavior of 4 and 5 in the cyclization reactions was interpreted in terms of the tautomeric equilibrium which was shifted towards the enamine form in 4, and towards the imine form, in 5. Transmission of a long‐range chirality effect in 4d and 5a‐d manifested itself in the 1H nmr spectra as the magnetic non‐equivalence of the CH2 protons in one or both ester ethyl groups.
Synthetic approaches to 4,8‐dimethyl‐5′‐(N‐pyridiniummethyl)‐ 4′,5′‐dihydropsoralens and 4,8‐dimethyl‐5′‐ (N‐aminomethyl)‐ 4′,5′‐dihydropsoralens
Authors: Whittemore Marilyn S. , Heindel Ned D. , Jabin Ivan , Guillon Christophe , Mcneel Thomas E. , Rapp Robert D. , Heck Diane E. , Laskin Jeffrey D. 
Published: March 2009

AbstractNew synthetic approaches to 4,8‐dimethyl‐5′‐(N‐pyridiniummethyl)‐4′,5′‐dihydropsoralens and 4,8‐dimemyl‐5′‐(N‐aminomethyl)‐4′,5′‐dihydropsoralens are described. The 5′‐halomethyl‐4′,5′‐dihydro‐psoralen precursors are formed by electrophilic ring closures of 4,8‐dimethyl‐6‐allyl‐7‐hydroxycoumarin. The ring‐closure reactions may also be applied to the synthesis of 5′‐halomethyl‐4‐methyl‐4′,5′‐dihydroangelicins. The compounds are potential therapeutic agents for improved psoralen ultraviolet A radiation treatment.
Synthesis and characterization of 7, 16‐bis(phenylazo)tetraaza[14]annulenes
Authors: Sakata Kazunori , Yamashita Junichi , Hashimoto Mamoru , Tsuge Akihiko , Tanoue Yasuhiro 
Published: March 2009

AbstractThe diazo coupling reaction between a tetraaza[14]annulene (1) and a series of 4‐substituted phenyl‐diazonium tetrafluoroborates yielded the corresponding 7, 16‐disubstituted products. Mass spectra indicate the presence of molecular ion peaks that substantiate the 7,16‐disubstituted products (4); the lack of olefinic proton signals corresponding to the 7,16‐ position in the 1H nmr spectra of 4 also show that diazo coupling has taken place. Analysis of signals corresponding to the methyl groups of 4 in their 1H and 13C nmr spectra indicate that the imine‐bis‐hydrazone form is present for compounds that do not contain p‐methoxyphenyl groups. However, analysis of methyl signals in the nmr specta of compounds 4 containing p‐methoxyphenyl groups show that the bis‐azo form and the imine‐bis‐hydrazone form are present through tautomerism. Complexation with nickel(II) ion induces the formation of the bis‐ azo structure.
A new synthesis of 4‐cyano‐1,3‐dihydro‐2‐oxo‐2H‐imidazole‐5‐(N1‐tosy1)carboxamide : reactive precursor for thiopurine analogues
Authors: Hamad Abdel‐Sattar S. , Derbala Hamed D. A. Y. 
Published: March 2009

AbstractN‐[(5‐Cyano‐2‐oxoimidazolidin‐4‐yl)‐iminomethyl]‐p‐toluensulfonamide 3 was prepared in fairly good yield by the base catalyzed cyclisation of N‐[(Z)‐2‐amino‐1,2‐dicycanovinylcarbamoyl]‐p‐toluenesulfon‐amide 2. The N‐[(Z)‐2‐amino‐1,2‐dicycanovinyl carbamoyl]‐p‐toluenesulfonamide 2 was reacted readily with two molar amount of p‐nitrobenzaldehyde at room temperature in the presence of base to give 7,8‐dihy‐dro‐2‐(4‐nitrophenyl)‐8‐oxo‐9‐tosylpurine‐6‐carboxamide 8. Thiation of compounds 3 and 8 using Lawesson's reagent in tetrahydrofuran gave novel thioimidazoles 4, 5, and 6 and thiopurines 9, 10, and 11, which have been characterized spectroscopically.
A kinetic study of the high temperature rearrangement of 4‐ethyl‐3,5‐diphenyl‐4H‐1,2,4‐triazole
Authors: Gautun Odd R. , Carlsen Per H. J. 
Published: March 2009

AbstractThe kinetics of the thermal rearrangement 4‐ethyl‐3,5‐diphenyl‐4H‐1,2,4‐triazoles, 1, to the corresponding 1‐ethyl‐3,5‐diphenyl‐1‐alkyl‐1H‐1,2,4‐triazoles, 2, was studied in 15‐Crown‐5 and octadecane at 330 °C. The reaction was very slow in octadecane but proceed well in 15‐Crown‐5. The reaction order for the reaction was not constant but changed from an initial second order rate law towards a first order rate law as the reaction progressed. This was confirmed by the concentration dependent reaction order, nc, which was larger than the time dependent rate law, nt. The rationale for the observation was, that at high substrate concentrations the reaction order was second order while at lower concentrations a competing solvent assisted reaction plays an increasing important role. The data were in agreement with a mechanism in which the neutral 4‐alkyl‐triazoles in an intermolecular nucleophilic displacement reaction form a triazolium triazolate, which in a subsequent nucleophilic reaction gives the observed product.