bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteropolycyclic molecules. Part IX. Synthesis of some new benzo[b]thiophene, oxofluoreno[4,3‐b]thiophene, cyclic hydrazides and acridine compounds
Authors: Moussa H. H. , Abdel‐Meguid S. 
Published: March 2009

Abstractp‐Tolyl 2‐thienyl ketone (I) condensed with dimethyl succinate in the presence of potassium t‐butoxide to give the trans (SC4H3/CO2Me) half‐ester (IIIa) whose configuration was deduced by cyclization to the corresponding benzo[b]thiophene derivatives. Carbamates, esters, cyclic hydrazides and substituted phenolic and acetic acids useful as antibacterial and antiinflamatory agents were obtained. The reaction of ketone I with malononitrile to give ylidenemalononitrile II was also considered.
Syntheses of some hydroxylated metabolites of psychotropic trifluoromethyl analogs of chlorpromazine
Authors: Nodiff E. A. , Sharma H. L. , Taunk P. C. , Shukla A. P. , Sadhnani M. D. , Tambi S. B. , Mital R. L. 
Published: March 2009

AbstractThe syntheses of 7‐hydroxy derivatives of trifluoperazine, nor,‐trifluoperazine, fluphenazine, triflupromazine and nor,‐triflupromazine are described. These were prepared as analytical standards for the identification of these metabolites in biological materials.
Ring transformation of condensed dihydro‐as‐triazines
Authors: Berényi E. , Benkó P. , Zólyomi G. , Tamás J. 
Published: March 2009

AbstractThe 2‐amino‐as‐triazino[6,5‐c]quinoline as well as 3‐aminopyrido[4,3‐e]‐as‐triazine had previously been synthetized by Berényi (1) and Benkó et al (2). In this paper, the ring transformation occuring in aqueous media of the dihydro intermediates and their salts, respectively appearing during the synthesis of 2‐substitutedamino‐as‐triazino[6,5‐c]quinolines, are reported.
Crystal and molecular structure of an active carbinolamide: 4‐hydro‐4‐dimethoxymethyl‐6‐isopropyl‐2‐oxo‐2,3‐dihydro(6H)‐1,3‐oxazine
Authors: Baker R. J. , Majeste R. J. , Trefonas L. M. 
Published: March 2009

AbstractThe crystal and molecular structure of the title compound has been determined by single‐crystal x‐ray diffraction techniques. The compound is of interest because of its own intrinsic anti‐tumor activity and because it is also a common moiety of a series of more active anti‐tumor agents, the maytansinoids. The compound crystallizes in the space group PĪ with 2 molecules in a unit‐cell of dimensions a = 6.912 Å,b = 7.219 Å,c = 15.272 Å, α = 119.96°, β = 104.30° and γ = 96.04°. The structure was solved by direct methods and refined to a final value of R = 0.063.
The crystal structure of 5‐amino‐6‐chloro‐4‐nitro‐2‐(β‐D‐ribofuranosyl)‐2H‐pyridazin‐3‐one
Authors: Castle Raymond N. , Thompson Robert Douglas , Dalley N. Kent , Simonsen Stanley H. , Larson Steven B. 
Published: March 2009

AbstractThe nucleoside, 5‐amino‐6‐chloro‐4‐nitro‐2‐β‐D‐ribofuranosyl‐2H‐pyridazin‐3‐one (4), was synthesized as part of a study to prepare potential chemotherapeutic compounds. An X‐ray crystal structure study of the compound was initiated in order to substantiate its formula and to examine its conformation and absolute configuration. The structure was determined using direct methods and refined to an R of 0.020 (Rw = 0.024). The compound has a glycosyl torsion angle of 71.2°. The structure contains three intermolecular hydrogen bonds and one intramolecular hydrogen bond.
Addition reactions of azoesters with 2‐thioquinazolinones
Authors: Giannola Libera Italo , Giammona Gaetano , Carlisi Bianca , Palazzo Salvatore 
Published: March 2009

AbstractReaction between diethyl azodicarboxylate (I) and 1,2,3,4‐tetrahydro‐2‐thioquinazolin‐4‐one (II), as a cyclic model of thiourea, both in alcoholic medium and in inert solvents has been investigated. By carrying out the reaction in an inert solvent, it was possible to isolate an intermediate. Evidence is presented that the intermediate, in turn, was converted into the final products. Structures were unequivocally assigned by mass spectrometry.
Synthesis and spectra of new 3‐carbethoxypyrazole sulfonylurea derivatives
Authors: Allah Hassan M. Faid , Mokhtar Hassan M. , Soliman R. 
Published: March 2009

AbstractThe reaction of 1‐benzenesulfonyl‐3‐ethoxycarbonyl‐5‐[α‐substituted‐styryl]pyrazoles (1) with isocyanate and thioisocyanate derivatives yield the corresponding benzenesulfonylurea derivatives (2and3). Bromination of1afforded the 4‐bromopyrazoles4which react with isocyanate derivatives giving5that were also obtained by bromination of2. Alkaline hydrolysis of the benzensulfonylurea derivatives2yield the corresponding pyrazole‐3‐carboxylic acids7.
Intramolecular meerwein reactions of the anthraquinone system. Synthesis, X‐ray structural analysis and spectroscopic properties of anthra[9,1‐bc:10,5‐b'c']tetrahydrodipyran derivatives
Authors: Fritz H. , Rihs G. , Sutter P. , Weis C. D. 
Published: March 2009

AbstractMeerwein reactions of 1,5‐anthraquinone bis(diazonium hydrogen sulfate) with sufficiently activated olefins, such as acrylonitrile, acrylic esters, methacrylonitrile and its esters, styrene and α‐methylstyrene yielded derivatives of the new heterocyclic system anthra[9,1‐bc:10,5‐b'c']‐2,3,7,8‐tetrahydrodipyran. Isolation of derivatives was realized and yields enhanced by using dimethyl methylphosphonate as reaction medium. Compounds 5–18 were isolated as mixtures of diastereomers, some of which were separated by crystallization. Proof of structure and stereochemistry was obtained for some of the compounds by X‐ray crystallographic analysis. The 1H‐ and 13C‐nmr data provided further support. Surprisingly large chemical shift differences between some of the proton signals of isomers were observed although the two asymmetric centers are far apart through bonds and through space. The mechanism of formation is explained on the basis of redox modulation of a charge transfer complex in which the aliphatic radical attacks the oxygen atom of the anthraquinone. It is proposed to classify this new type of reaction as an intramolecular Meerwein reaction.
Antiarrhythmika. I. 2,4‐dialkylpyrimido[1,2‐a]benzimidazole
Authors: Kreutzberger Alfred , Leger Manfred 
Published: March 2009

AbstractAus der Umsetzung von 2‐Aminobenzimidazol (1) mit β‐Diketonen (2a‐d) gehen die 2,4‐Dialkylpyrimido[1,2‐a]benzimidazole (3a‐d) hervor.
Naphtho[1′,2′:5,6]pyrano[2,3–6][1,5]benzodiazepine Derivatives
Authors: Roma Giorgio , Ermili Aldo , Balbi Alessandro , Massa Elda , Di Braccio Mario 
Published: March 2009

AbstractThe reaction of 3‐(dimethylamino)‐1‐oxo‐1H‐naphtho[2,1‐b]pyran‐2‐carbaldehyde (Ia) with o‐phenylenediamines or N‐monosubstituted o‐phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho[1′,2′:5,6]pyrano[2,3‐b][1,5]benzodiazepin‐15‐(8H)ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N‐monosubstituted o‐phenylenediamine hydrochlorides. The isolation of a significant intermediate as well as the synthesis through a different univocal pathway confirmed the structure of the compounds V.Moreover the reaction of Ia with N‐monosubstituted o‐phenylenediamines in refluxing pyridine generally afforded only low yields of compounds V, sometimes together with naphtho[1′,2′:5,6]pyrano[2,3‐b][1,5]benzodiazepin‐15‐(13H)ones VII, isomers of V.
Synthesis of new fulvenes containing heterocyclic substituents
Authors: Knight David B. , Hall Randall W. , Cleary Darryl G. 
Published: March 2009

AbstractFour new fulvene derivatives bearing heterocyclic substituents have been prepared. Base‐promoted condensation of cyclopentadiene with tetrahydropyran‐4‐one, tetrahydrothiopyran‐4‐one, and 1‐methyl‐4‐piperidone afforded 4‐(cyclopentadienylidene)tetrahydropyran 1, 4‐(cyclopentadienylidene)tetrahydrothiopyran 2, and N‐methyl‐4‐(cyclopentadienylidene)piperidine 3 in yields ranging from 28% to 75%. Methylation of 3 with methyl iodide gave the corresponding ammonium salt, 4.
Pechmann reaction of 4‐hydroxycoumarins and thiocoumarins with cyclohexanone and ethyl cyclopentanone‐2‐carboxylates
Authors: Merchant J. R. , Koshti N. M. , Bakre K. M. 
Published: March 2009

AbstractThe Pechmann reaction of 4‐hydroxycoumarins with cyclohexanone and ethyl cyclopentanone‐2‐carboxylates affords 1,2,3,4‐tetrahydro[2]benzopyrano[4,3‐c][1]benzopyran‐5,12‐diones and cyclopenta[3′,4′]pyrano‐[3,2‐c][1]benzopyran‐4,11‐diones. Dehydrogenation of the former yields [2]benzopyrano[4,3‐c][1]benzopyran‐5,12‐diones. Alkaline hydrolysis of a typical compound Va affords 2‐hydroxy‐2′‐carboxydeoxybenzoin which on boiling with acetic anhydride gives an isocoumarin derivative.
Monoamine oxidase and succinate dehydrogenase inhibitory properties of substituted 1,3,4‐oxadiazole‐2‐thiones
Authors: Soni Namita , Barthwal J. P. , Saxena A. K. , Bhargava K. P. , Parmar S. S. 
Published: March 2009

AbstractFifteen new 3‐arylaminomethyl‐5‐(2‐hydroxy‐3,5‐dibromophenyl)‐1,3,4‐oxadiazole‐2‐thiones were synthesized and characterized by their sharp melting points, elemental analyses and ir spectra. These substituted oxadiazolylthiones were evaluated for their enzyme inhibitory activity. All compounds inhibited in vitro monoamine oxidase and succinate dehydrogenase activity of rat brain homogenates. The degree of monoamine oxidase inhibition ranged from 59‐93% at a final concentration of 1 × 10−4 M whereas the inhibition of succinate dehydrogenase was 49‐100% at a final concentration of 5 × 10−5 M.
Rearrangement of 3‐arylhydantoins into 3‐aminoglycocyamidines
Authors: Daboun Hamed A. , Ibrahim Yehia A. 
Published: March 2009

AbstractThe action of hydrazine hydrate on 5‐arylidene‐3‐aryl‐2‐methylmercaptohydantoins led to ring opening and rearrangement into 5‐arylidene‐3‐amino‐N2‐aryl‐glycocyamidines (9a‐f). The structure of the products 9a‐f was established and the mechanism of their formation was discussed.
Mass spectral fragmentation pattern of 5‐methyl‐4‐[(phenylamino)methylene]‐2,4‐dihydro‐3h‐pyrazol‐3‐one and its 2‐methyl and 2‐phenyl derivatives
Authors: Keats Neil G. , Rockley Jean E. , Summers Lindsay A. 
Published: March 2009

AbstractThe mass spectral fragmentation patterns of 5‐methyl‐4‐[(phenylamino)methylene]‐2,4‐dihydro‐3H‐pyrazol‐3‐one and its 2‐methyl and 2‐phenyl derivatives have been elucidated. The principal initial fragmentation route involves rupture of the exocyclic CH‐NH bond. Minor routes involve loss of H, OH and C6H5 from the molecular ion and rupture of the pyrazolone ring.
Reaction of diazoindenothiophenes with mono‐ and dibenzoylacetylenes
Authors: Mataka Shuntaro , Ohshima Takeshi , Tashiro Masashi 
Published: March 2009

AbstractReaction of diazoindenothiophenes (1 and 2) with benzoyl acetylene (4) afforded the rearrangement products (6a and b) of the initial adducts. The major product of the reaction of diazo indenothiophene (3) with 4 was butadiene derivative 8a. Reaction of 1 with dibenzoylacetylene (5a) gave the rearranged pyrazole (12), while the reaction of 2 and 3, afforded the butadiene derivatives (8b‐d).
5‐Bromobenzofuran Analog of Chloramphenicol
Authors: Bevinakatti Hanamanthsa S. , Badiger Virupax V. 
Published: March 2009

Abstractdl‐threo‐2‐Dichloroacetamido‐1‐[2‐(5‐bromobenzofuranyl)] propane‐1, 3‐diol (7) was synthesised according to Sorm's method. The fragmentation of 2‐dichloroacetamido‐3‐hydroxy‐1‐[2‐(5‐bromobenzofuranyl)[‐1‐propanone (6) under electron impact is reported. The base peak is due to the rupture of the central bond whereas loss of water and McLafferty rearrangement also lead to important fragmentation pathways.
A one step synthesis of thiadiazolo[2,3‐b]quinazoline derivatives
Authors: Shawali Ahmad S. , Abdelhamid Abdou O. , Hassaneen Hamdi M. , Shetta Abdelfattah 
Published: March 2009

AbstractDiazotized anthranilic acid and its methyl ester react with substituted phenacyl thiocyanates 3 to give in both cases the corresponding thiadiazolo[2,3‐b]quinazolines 7a‐e. A mechanism is proposed and it is substantiated by alternate synthesis of 7a from the hydrazidoyl chlorides 9a,b and potassium thiocyanate.
Ortho effects of a nitro group in 2′,3′ and 4′monosubstituted‐trans‐2,4‐dinitrostilbenes on electron impact. IV
Authors: Zugazagoitia R. , Martínez R. , Cortés E. 
Published: March 2009

AbstractThe mass spectral fragmentation patterns of thirteen 2′,3′ and 4′‐R‐trans‐2,4‐dinitrostilbenes obtained by electron impact have been studied. The main routes of fragmentation involves loss from the molecular ion due to the ortho effects of the 2‐nitro substituents. Substitution on positions 2′,3′ and 4′ of stilbene moiety does not influence the fragmentation patterns.
Studies on the synthesis of heterocyclic compounds. VII. Action of acyl halides on heterocyclic compounds containing the O‐M‐O (M  P, As, Sb) bond in the ring
Authors: Anchisi Carlo , Corda Luciana , Maccioni Antonio , Podda Gianni 
Published: March 2009

AbstractThe action of acyl halides on heterocyclic compounds of five‐membered rings containing an O‐M‐O (M  P, As, Sb) linkage is described. The reactions were either carried out in the presence of a solvent (benzene or toluene) or by direct heating of the reagent with the substrate. In the case of arsole, stibole and stannole derivatives, the cleavage of O‐M bond and the formation of the respective mono‐ and diesters were always obtained, while with the phospholes, no cleavage of the compounds was observed. The products IIa‐c (M = Sb) have been obtained in excellent yields starting from VIa‐c and antimony trichloride. The structure of the compounds which were prepared was determined by analytical and spectroscopic methods and also by comparations with authentic samples where possible.
Purine analogues as potential chemotherapeutic agents. III
Authors: Ram Vishnu J. , Pandey H. K. , Vlietinck Arnold J. 
Published: March 2009

AbstractAlkylation of 3‐phenyl/benzyl‐8‐mercaptoxanthines and 2‐phenyl‐8‐mercaptoadenine with various alkyl halides under different conditions is studied. The structure of the compounds is confirmed by spectroscopic studies and elemental analyses.
Functionalization at C‐5 and at the C‐6 methyl group of 4‐methoxy‐6‐methyl‐2‐pyrone
Authors: Bacardit R. , Moreno‐Mañas M. , Pleixats R. 
Published: March 2009

AbstractA new entry to C‐5 substituted 4‐hydroxy‐6‐methyl‐2‐pyrones has been achieved. The best conditions to prepare the monobromo and the dibromo derivatives at C‐3 and the C‐6 methyl group of the title pyrone have been defined. The synthetic applicability of the phosphonium salts at CH3‐C‐6 of both 4‐methoxy‐6‐methyl‐2‐pyrone, 5, and dehydroacetic acid, 2, has also been evaluated.
New guaianolides from Berlandiera Pumila and B. Texana, and the X‐ray crystal structure of pumilin
Authors: Korp James D. , Bernal Ivan , Fischer Nikolaus H. , Leonard Charles , Lee Ihl‐Young , LeVan Ngo 
Published: March 2009

AbstractThe isolation and structure determination of two new guaianolides, pumilin and its 2,3‐epoxide, from Berlandiera pumila and B. texana are reported. The structure of pumilin was determined from nmr and mass spectral data, and from an X‐ray single crystal study; the structure of the epoxide was found by comparison of nmr spectra. Pumilin is shown to be a Δ1(10)‐cis‐guaianolide with a cyclopentenone ring attached to C1 and C5, and an α‐methylene‐γ‐lactone ring trans‐fused to C6 and C7. The absolute configuration was inferred from spectral considerations and knowledge of previous structural determinations. The cd spectrum of pumilin exhibits a negative Cotton effect, and the lactone chromophore has left‐handed chirality. The cyclo‐heptene ring is in the chair configuration, with the lactone a half‐chair and the cyclopentenone essentially planar. Crystals are orthorhombic, a = 7.065, b = 13.652, c = 19.586 Å, space group P212121, Z = 4, and the final R value is 3.9%. The crystal structure is strengthened by an O···O hydrogen bond linking the molecules into infinite chains.
Synthesis of some 5H‐benzo[a]phenoxazin‐5‐one derivatives
Authors: Ueno Yoshio , Maeda Keiichi , Koshitani Jinya , Yoshida Takatoshi 
Published: March 2009

AbstractThe substituted 6‐bromo and 6‐chloro‐5H‐benzo[a]phenoxazin‐5‐ones, prepared by condensation of substituted 2‐aminophenols with 2,3‐dibromo or 2,3‐dichloro‐1,4‐naphthoquinone in methanolic potassium hydroxide solution, have been dehalogenated to substituted 5H‐benzo[a]phenoxazin‐5‐ones in the presence of sodium hydrosulfite dissolved in aqueous pyridine under nitrogen atmosphere.
Synthesis and properties of 7‐hydroxy‐8‐phenylxanthine and its derivatives. Disproportionation to derivatives of 8‐phenylxanthine and 6‐amino‐5‐nitrosouracil
Authors: Zvilichovsky Gury , Garbi Herzel , Nemes Eliahu 
Published: March 2009

Abstract8‐Phenyl, 8‐(p‐methoxyphenyl) and 8‐(p‐chlorophenyl)‐7‐hydroxyxanthine were synthesized by ring closure of 6‐amino‐5‐nitrosouracil with benzaldehyde, p‐methoxybenzaldehyde and p‐chlorobenzaldehyde, respectively. The disproportionation of these products to the corresponding 8‐phenylxanthines and 6‐amino‐5‐nitrosouracil was studied. The dependence of the rate of the reaction on the various substituents was studied. The disproportionation reaction is inhibited by the polarophilic ethyl acetylenedicarboxylate and enhanced by phosphate.
New synthesis of 2‐nitroimidazoles
Authors: Davis Dwight P. , Kirk Kenneth L. , Cohen Louis A. 
Published: March 2009

Abstract1‐Triphenylmethylimidazoles are treated with n‐butyllithium in tetrahydrofuran at 0° to form the 2‐lithio derivatives. The latter species react with n‐propyl nitrate to give l‐trityl‐2‐nitroimidazoles which, after acid hydrolysis, provide the corresponding 2‐nitroimidazoles. 2‐Nitroimidazole was obtained from imidazole in overall yields of 27–35% 4‐methyl‐2‐nitroimidazole was obtained in 40% overall yield from 4‐methyl‐imidazole. Imidazole‐4,5‐dicarboxylic acid was converted, in several steps, to l‐tritylimidazole‐4‐methanol, and the latter compound was transformed into 2‐nitroimidazole‐4‐methanol in an overall yield of 18%. Protection of the hydroxymethyl function was found to be unnecessary during carbanion formation and nitration. Attempts to nitrate 1‐methylimidazole or 1‐methoxymethylimidazole by the same procedure failed.
Reaction of ketenes with N,N‐disubstituted α‐aminomethyleneketones. XII. Synthesis of N,N‐disubstituted 4‐amino‐3‐chloro‐6‐(2‐methyl‐l‐propenyl) (2‐phenylethenyl)‐2H‐pyran‐2‐ones
Authors: Bargagna Alberto , Schenone Pietro , Bondavalli Francesco , Longobardi Mario 
Published: March 2009

AbstractCycloaddition of dichloroketene to N,N‐disubstituted (E)‐amino‐5‐methyl‐1,4‐hexadien‐3‐ones IV and (E,E)‐1‐amino‐5‐phenyl‐1,4‐pentadien‐3‐ones V occurred in moderate to good yield only in the case of aromatic N‐substitution to give N,N‐disubstituted 4‐amino‐3,3‐dichloro‐3,4‐dihydro‐6‐(2‐methyl‐l‐propenyl) (2‐phenylethenyl)‐2H‐pyran‐2‐ones, which were dehydrochlorinated with DBN to afford in good yield N,N‐disubstituted 4‐amino‐3‐chloro‐6‐(2‐methyl‐propenyl)(2‐phenylethenyl)‐2H‐pyran‐2‐ones. In the case of aliphatic N,N‐disubstitution (dimethylamino group) of enaminones IV and V, the Cycloaddition led directly in low yield to 3‐chloro‐4‐dimethylamino‐6‐(2‐methyl‐l‐propenyl)(2‐phenylethenyl)‐2H‐pyran‐2‐ones.
Convenient preparation of N‐substituted 2‐amino‐4H‐3,l‐benzoxazin‐4‐ones and 3‐substituted 2,4(1H,3H)‐quinazolinediones
Authors: Papadopoulos E. P. , Torres C. D. 
Published: March 2009

AbstractRoom temperature treatment of 2‐(3‐arylureido)benzoic acids (1) and methyl 2‐(3‐alkyl‐, or 3‐arylureido)‐ benzoates (2) with concentrated sulfuric acid leads to N‐substituted 2‐amino‐4H‐3,l‐benzoxazin‐4‐ones (3) in generally very good yields. The isomeric 3‐substituted 2,4(1H,3H)‐quinazolinediones (4) are conveniently made in high yield by the action of aqueous‐ethanolic sodium hydoxide on 2.
A synthesis of 5‐amino‐ and 5‐hydroxy‐l‐ethyl‐1,4‐dihydrio‐4‐oxo‐3‐quinolinecarboxylic acids and their derivatives
Authors: Tamura Yasumitsu , Fujita Masanobu , Chen Ling Ching , Ueno Kyoji , Kita Yasuyuki 
Published: March 2009

AbstractThe synthesis and antimicrobial activity of 5‐Hydroxy‐l‐ethyl‐1,4‐dihydrio‐4‐oxo‐3‐quinolinecarboxylic acids and their derivatives have been investigated. The 5‐hydroxy‐3‐quinolinecarboxylic acids were prepared by thermal cyclization of 3‐oxocyclohexenylaminomethylenemalonates followed by aromatiza‐tion with iodine‐ethanol, ethylation and hydrolysis of products. The 5‐amino derivatives were prepared by several steps involving novel aromatization of isoxazole intermediates.
Synthesis of as‐triazino[5,6‐b]quinoline, a new heterocyclic ring system
Authors: Hajpál István , Berényi Edit 
Published: March 2009

AbstractThe first representatives of a new ring system, 3‐oxo‐2,3,4,10‐tetrahydro‐as‐triazino[5,6‐b]quinoline and some of its derivatives were synthesized by cyclization of the appropriate (2‐aminobenzyl)‐triazines. These substances are in equilibrium with the tautomer 1,2,3,4‐tetrahydro form.
Etude de l'acylation de l'acétyl‐3 acétoxy‐8 indolizine par action de chlorures d'acide en présence de chlorure d'aluminium
Authors: Sliwa Henri , Blondeau Dominique 
Published: March 2009

AbstractL'etude de l'acylation de l'acétyl‐3 acétoxy‐8 indolizine par action de chlorures d'acide divers en présence de chlorure d'aluminium montre que la réaction peut soit se limiter à une transestérification (cas du chlorure de benzoyle) soil se traduire par l'introduction d'un groupe acyle en ‐1 avec libération concomitante de la fonction phénol en ‐8; au cours de cette acylation en ‐1, le chlorure d'acétyle libere par clivage du groupe acétoxyle entre en compétition avec le chlorure d'acide mis en jeu. Ce dernier l'emporte dans le cas du chlorure d'éthoxalyle et des chlorures d'alcanoyle non ramifies; par contre on observe uniquement l'acétyla‐tion lorsqu'on met en oeuvre le chlorure de pivaloyle ou de phenylacetyle.Une interprétation des resuitats mettant en jeu un processus analogue à la transposition de Fries est propose. L'hypothese d'un transfert intramoleculaire d'un groupe acyle de la fonction ester en ‐8 sur la position ‐1 est écartée au vu des résultats observés.
Dérives de l'imidazo[2,1‐b]thiazole. V. Transposition allylique observée au cours de la synthése d'(imino‐2 alkyl‐3 thiazolinyl‐4) acetates d'ethyle et de (dihydro‐5,6 imidazo[2,1‐b]thiazolyl‐3) acetates d'éthyle
Authors: Robert Jean‐Francois , Panouse Jacques J. 
Published: March 2009

AbstractLe bromhydrate de (phényl‐6 dihydro‐5,6 imidazo[2,1‐b]thiazolyl‐3) acétate d'éthyle subit une transposition allylique en milieu alcalin pour donner le (phényl‐6 tétrahydro‐2,3,5,6 imidazo[2,1‐b]thiazolylidene‐3) acétate d'éthyle. Celui‐ci présente une double liaison juxtanucléaire qui persiste apres acidification. Les differents (imino‐2 alkyl‐3 thiazolinyl‐4) acetates d'ethyle utilises comme intermidiaires de synthese subissent une transposition analogue sous forme de base. Mais apres acidification il y a retour a une structure thiazolique. Les donnees rmn protoniques sont utilisees pour expliquer ces transpositions sous l'influence du pH, qui font egalement intervenir les contraintes stériques et l'existence de conjugaison π p π.
Unusual formation of an oxetane ring. Molecular and crystal structure of 2a‐acetyl‐3‐(1‐methoxyethylidene)‐5a‐methylcyclopenta[b]oxetan‐4‐one
Authors: Adembri Giorgio , Donati Donato , Lampariello Lucia R. , Scotton Mirella 
Published: March 2009

AbstractThe reaction between 2,3‐diacetyl‐4‐hydroxy‐4‐methylcyclopent‐2‐en‐1‐one, 2, and diazomethane gave a mixture of four compounds, two of which, 5 and 6, resulted to be cyclopenta[b]oxetane derivatives. The structure of 5 was determined by X‐ray analysis. Some aspects of the mechanism are discussed.