bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemical reactions of β‐aminovinyl aryl thioketones
Authors: Nishio Takehiko , Nakajima Naoko , Omote Yoshimori 
Published: March 2009

AbstractIrradiation of β‐aminovinyl aryl thioketones (1a‐b) afforded β‐aminovinyl aryl ketones (2a‐b). 2H‐Thiopyran derivatives (4a‐b) were obtained when β‐aminovinyl phenyl thioketone (1a) was irradiated with methyl acrylate and acrylonitrile. 4H‐Thiopyran derivatives (6,8) were also obtained thermally in the reaction of β‐aminovinyl phenyl thioketone (1a) and methyl propiolate and maleic anhydride.
Chemistry of the phenoxathiins and isosterically related heterocycles. IX.N‐oxidation on the 13C‐nmr chemical shifts and coupling constants of the 1‐azaphenoxathiin system
Authors: Martin Gary E. 
Published: March 2009

AbstractThe synthesis of 1‐azaphenoxathiin N‐oxide is described. Total assignment of the 13C‐nmr spectrum and the effects of the N‐oxide moiety on the chemical shifts and 1H‐13C spin couplings constants are described and compared to the parent 1‐azaphenoxathiin system. The potential for the use of N‐oxidation induced changes in 13C‐nmr chemical shifts and 1H‐13C coupling constants as an assignment criterion is also discussed.
Reissert compound studies. XXXIV. Base‐catalyzed reactions of the phthalazine reissert compound
Authors: Bhattacharjee D. , Popp F. D. 
Published: March 2009

AbstractThe phthalazine Reissert compound has been used to convert phthalazine to 1‐benzylphthalazines, bisbenzylphthalazines, 1,4‐disubstituted phthalazines, 1‐cyanophthalazine, and a number of other phthalazine derivatives including the tricyclic compound 14.
Synthesis and reactivity of a series of [14]azaannulenes
Authors: Place David A. , Ferrara Gerald P. , Harland Joseph J. , Dabrowiak James C. 
Published: March 2009

AbstractUsing a metal template reaction, a series of [14]azaannulenes formed from a β‐diketone and an aromatic diamine in the presence of nickel(II) have been synthesized. Attempted cyclizations with bulky β‐diketones and certain substituted diamines showed that the cyclization is sensitive to steric effects. At least one of the nickel complexes readily reacts with a series of nucleophilic reagents to give methine‐substituted products.
One‐step preparation of 3‐alkoxypyrazine‐2‐carbonitriles from pyrazine‐2,3‐dicarbonitriles and related reactions
Authors: Kojima Takakazu , Nagasaki Fumihiko , Ohtsuka Yozo 
Published: March 2009

AbstractA series of 5,6‐disubstituted 3‐alkoxypyrazine‐2‐carbonitriles (2a‐i) were prepared from 5,6‐disubstituted pyrazine‐2,3‐dicarbonitriles (1a‐d) by direct substitution with alcohols. Treatment of 1 with amines gave either pyrrolopyrazines (3a,b) or substitution products (4,5). In a low temperature range, 1 afforded imidates and related compounds (6–11). The preference among these reactions depended on the 5,6‐substituents and on the reaction conditions.
Studies of spiro‐chlorin formation using porphyrin amides
Authors: Smith Kevin M. , De Almeida José A. P. Baptista , Lewis W. Michael 
Published: March 2009

AbstractSyntheses of 7‐(3‐ethoxycarbonylpropyl)‐2,3,5‐triethyl‐1,4,6,8‐tetramethylporphyrin (8) (via the MacDonald dipyrrylmethane route) and 2‐(2‐chloroethyl)‐4‐ethyl‐6‐methoxycarbonyl‐7‐(3‐methoxy‐carbonylpropyl)‐1,3,5,8‐tetramethylporphyrin (22) (via the tripyrrene route) are described. The corresponding pyrrolidides of these compounds were cyclized in high yield to furnish the spiro imines (20 and 30 respectively), but attempts to hydrolyze these imines to the appropriate spiroketochlorins were largely unsuccessful. A small amount of the spiroketochlorin 9 (from 8) was obtained, and this was successfully hydrogenated to give the dihydro derivative 21. The major problem in imine hydrolysis was observed to be reversion to the parent porphyrin through simple bond migration and spiro ring cleavage. A successful transformation of protoporphyrin‐IX dimethyl ester (31) into mesoporphyrin‐IX dimethyl ester (32) using di‐imide generated from dipotassium azodicarboxylate is described.
(2‐Alkyl‐1,4‐benzodioxan‐2‐yl)carboxylic acids as potential hypolipidemic agents
Authors: Salimbeni Aldo , Manghisi Elso 
Published: March 2009

Abstract1,2‐Diphenols reacted with 2‐alkyl‐3‐chloro‐1,2‐epoxypropane to give a mixture of 1,4‐benzodioxane, V, and 1,5‐benzodioxepine, VII, alcohols. From potassium permanganate oxidation of benzodioxane compounds V the corresponding (2‐alkyl‐1,4‐benzodioxan‐2‐yl)carboxylic acids II were obtained. In a preliminary pharmacological evaluation benzodioxane acids II did not show any effect on plasma cholesterol, while producing a moderate lowering of triglycerides.
Synthesis of 6‐(arylthio)‐ and 6‐[(arylmethyl)thio] ‐1,2,4,5‐tetrazin‐3‐amines and n‐phenyl‐ and n‐(phenylmethyl)‐1,2,4,5‐tetrazine‐3,6‐diamines as potential antimalarial agents
Authors: Johnson Judith L. , Whitney Barbara , Werbel Leslie M. 
Published: March 2009

AbstractAlkylation of tetrahydro‐1,2,4,5‐tetrazine‐3,6‐dithione with iodomethane and 1,2‐dichloro‐4‐(chloromethyl)benzene, respectively (Scheme 1, 4) followed by oxidation afforded 3,6‐bis(methylthio)‐ and 3,6‐bis[[(3,4‐dichlorophenyl)methyl]thio]‐1,2,4,5‐tetrazines (6, 15). The reaction of 15 with amines provided the 6‐[(arylmethyl)thio]‐1,2,4,5‐tetrazin‐3‐amines (16) while sequential displacement of both methylthio groups in 6 afforded the tetrazine‐diamines 8 and 10. Hydrolysis of N,N‐dimethyl‐6‐(methylthio)‐1,2,4,5‐tetrazin‐3‐amine (11) with potassium hydroxide afforded the tetrazin‐3‐ol (12) which was chlorinated and then treated with 4‐chlorobenzenethiol to provide 13. The target 6‐substituted‐1,2,4,5‐tetrazin‐3‐amines displayed negligible antimalarial activity.
Reaction of ketenes with N,N‐disubstituted α‐aminomethyleneketones. X. Synthesis of N,N‐disubstituted 6‐alkyl‐4‐amino‐3,3‐dichloro‐3,4‐dihydro‐2H‐pyran‐2‐ones and of 6‐alkyl‐4‐amino‐3‐chloro‐2H‐pyran‐2‐ones
Authors: Bargagna Alberto , Cafaggi Sergio , Schenone Pietro 
Published: March 2009

AbstractCycloaddition of dichloroketene to N,N‐disubstituted 1‐amino‐4‐methyl‐1‐penten‐3‐ones and 1‐amino‐4,4‐dimethyl‐1‐penten‐3‐ones occurred in moderate to fair yield only in the case of aromatic N‐substitution to give N,N‐disubstituted 6‐alkyl‐4‐amino‐3,3‐dichloro‐3,4‐dihydro‐2H‐pyran‐2‐ones, which were dehydrochlorinated with DBN to afford in good yield N,N‐disubstituted 6‐alkyl‐4‐amino‐3‐chloro‐2H‐pyran‐2‐ones. In the case of aliphatic N,N‐disubstitution, cyclo‐addition led directly to 6‐alkyl‐4‐dialkylamino‐3‐chloro‐2H‐pyran‐2‐ones only for N,N‐disubstituted 1‐amino‐4,4‐dimethyl‐1‐penten‐3‐ones. The reaction between 1‐dimethylamino‐4‐methyl‐1‐penten‐3‐one and dichloroketene gave 3‐chloro‐4‐dimethylamino‐3,6‐dihydro‐6‐isopropylidene‐2H‐pyran‐2‐one in low yield.
The synthesis of polycyclic benz‐fused pyrroles
Authors: Anderson Wayne K. , Mcpherson Howard L. , New James S. 
Published: March 2009

AbstractPyrrolo[1,2‐f]phenanthridine (2), benzo[f]pyrrolo[2,1‐a]isoquinoline (3), 5,6,7,8,9,10,11‐hexahydrobenzo[g]pyrrolo[2,1‐a]isoquinoline (5), and pyrrolo[2,1‐a]isoquinoline (6) dicarboxylic acid diesters were prepared in 1,3‐dipolar cycloaddition reactions between dimethyl acetylenedicarboxylate and the hydrofluoroborate salt of the appropriate Reissert compound. Several of the different methods to prepare Reissert compounds are compared and the carbon‐13 nmr spectra for the Reissert compounds are reported. Carbon‐13 nmr was used to assign the structures of isomers 10 and 11; the latter compounds arose from a prior reaction in which the cyclization of β‐(5,6,7,8‐tetrahydro‐2‐naphthyl)ethylamine N‐formate which gave a mixture of hexahydroisoquinolines, 8a and 9a. Pyrrolo[1,2‐b]isoquinoline (12) and pyrrolo[2,1‐a]isoquinoline dicarboxylic acid diesters were made in münchnone cycloaddition reactions. The latter compound was made from tetrahydroisoquinoline‐1‐carboxylic acid which was readily prepared from isoquinaldic acid by catalytic reduction. The dehydrogenation of several of the partially saturated compounds is also discussed.
Hydrazinolysis of 4‐acyl and 4‐ethoxycarbonyl‐3H‐imidazo[1,5‐b]‐pyridazine‐5,7‐(6H)diones: 8‐Oxo‐1,4,7,8‐tetrahydropyridazino‐[4,5‐c]pyridazine, 8‐oxo‐7,8‐dihydropyridazino[4,5‐c]pyridazine and 5,8‐dioxo‐1,4,5,6,7,8‐hexahydropyridazino[4,5‐c]pyridazine derivatives
Authors: Migliara Onofrio , Petruso Salvatore , Sprio Vincenzo 
Published: March 2009

AbstractReaction of 4‐acyl‐3H‐imidazo[1,5‐b]pyridazine‐5,7‐(6H)diones with hydrazine hydrate gave 3R‐5R′‐8‐oxo‐1,4,7,8‐tetrahydropyridazino[4,5‐c]pyridazine together with 3R‐5R′‐8‐oxo‐7,8‐dihydropyridazino[4,5‐c]pyridazine derivatives. Their structures were assigned by means of elemental analyses and spectroscopic data (ir, uv, nmr and ms). The conclusive structural elucidation involved the fact that 2R‐4‐ethoxycarbonyl‐3H‐imidazo[1,5‐b]pyridazine‐5,7‐(6H)‐diones treated with hydrazine hydrate afforded 3R‐5,8‐dioxo‐1,4,5,6,7,8‐hexahydropyridazino‐[4,5‐c]pyridazine which, upon dehydrogenation, gave products previously reported in the literature.
Benzo[c]fused isothiazoles. I. synthesis of the angular benzo[c]bisisothiazoles and of the symmetrical benzo[c]trisisothiazole
Authors: Danylec Basil , Davis Michael 
Published: March 2009

AbstractThe synthesis of all the possible angular benzo[c]bisisothiazoles (1, 2 and 3), and of the symmetrical benzo[c]trisisothiazole (4) are described. The pmr properties of these compounds are compared with analogous thiophenes and thiadiazoles
Benzo[c]fused isothiazoles. II. Synthesis of some angular isothiazolo[c]benzothiadiazoles. An anomalous amination reaction
Authors: Danylec Basil , Davis Michael 
Published: March 2009

AbstractThe syntheses and pmr properties of the angular isothiazolo[c]‐2,1,3‐benzothiadiazoles (1 and 2) are described. An unusual electrophilic amination reaction with N‐sulfinylmethanesulfonamide is discussed.
Selenium heterocycles. XXX. Synthesis of 4‐substituted vinyl 2‐thioxo‐1,3‐dithioles and 5‐substituted vinyl 2‐thioxo‐1,3‐thiaselenoles
Authors: Shafiee A. , Vosooghi M. , Lalezari I. 
Published: March 2009

Abstract4‐Substituted vinyl and 4‐(4‐phenyl‐1,3‐butadienyl)‐1,2,3‐thiadiazoles were prepared through the reaction of 4‐aryl‐3‐buten‐2‐one semicarbazone and 6‐phenyl‐3,5‐hexadien‐2‐one semicarbazone with thionyl chloride, respectively. Decomposition of these 1,2,3‐thiadiazoles as well as the corresponding 1,2,3‐selenadiazoles with base and subsequent addition of carbon disulfide afforded 4‐substituted vinyl 2‐thioxo‐1,3‐dithioles and 5‐substituted vinyl 2‐thioxo‐1,3‐thiaselenoles.
Polycyclic azines. III. Synthesis of 3‐aminoimidazo[1,5‐a]pyridine derivatives by cyclodesulfurization of N′‐Substituted‐N‐(2‐pyridylmethyl)thioureas with dicyclohexylcarbodiimide
Authors: Bourdais J. , Omar A.‐Mohsen M. E. 
Published: March 2009

AbstractA series of 3‐substituted aminoimidazo[1,5‐a]pyridine derivatives have been synthesized by cyclodesulfurization of a variety of N′‐substituted‐N‐(2‐pyridylmethyl)thioureas with dicyclohexylcarbodiimide (DCCD). 1H Nmr spectral analysis of all synthesized compounds is given.
Synthesis of 4,7‐dimethoxyindoles bearing substituents at the c‐5 and c‐6 positions and studies on their demethylation products
Authors: Malesani Giorgio , Galiano Fabio , Ferlin Maria Grazia , Masiero Sergio 
Published: March 2009

AbstractSyntheses of some 4,7‐dimethoxyindoles bearing methyl, amino or acetamido groups at the C‐5 and C‐6 positions were investigated. The presence of these substituents made possible the isolation of the corresponding 4,7‐dihydroxyindole derivatives obtained by long reflux with aluminium chloride in benzene solution.
An infrared study on N‐methyloxazolidine‐2‐thione and ‐2‐selenone
Authors: Devillanova Francesco A. , Verani Gaetano 
Published: March 2009

AbstractAn infrared investigation on N‐methyloxazolidine‐2‐thione and ‐2‐selenone in the range 4000–200 cm−1 is reported. The direct comparison of the ir spectra for these compounds allowed us to identify the vibrations related to CS and CSe, and support the previous assignments of the CS modes in the oxazolidine‐2‐thione; for this compound it has not been possible to synthesize its selenium isologue. On the whole, these experimental assignments are in agreement with those reported for oxazolidine‐2‐thione. The CS and CSe modes, contributing to the bands falling below 600 cm−1, are compared with those of several similar pentaatomic rings.
Novel synthesis of the pharmacologically important 1‐substituted‐6‐phenyl‐4H‐s‐triazolo[4,3‐a][1,4]benzodiazepines
Authors: Hester Jackson B. 
Published: March 2009

AbstractSeveral 6‐phenyl‐4H‐s‐triazolo[4,3‐a][1,4]benzodiazepines have useful biological activity both in experimental animals and in man. This manuscript describes a novel synthesis of these compounds from intermediates that do not have a pre‐formed benzodiazepine ring system.
The behaviour of 3‐methyl‐5‐(o‐r‐styryl)‐4‐nitroisoxazoles under electron impact. I
Authors: Martíanez R. , Cortéas E. 
Published: March 2009

AbstractThe mass spectra of several 3‐methyl‐5‐(o‐R‐styryl)‐4‐nitroisoxazoles have been studied. The fragmentation patterns and mechanisms postulated have been confirmed by the determination of the metastable peaks.
The structure of some methyl and benzyl malonate derivatives of pyrimidine
Authors: Reynolds G. Fredric , Fenwick Marc B. 
Published: March 2009

AbstractReaction of 2,4,6‐trichloropyrimidine with sodium dibenzylmalonate in p‐dioxane gave 4,6‐dichloro‐2‐(dibenzylmalonyl)pyrimidine, while reaction of 2,4,6‐trichloropyrimidine with sodium dimethylmalonate yielded both 4,6‐dichloro‐2‐(dimethylmalonyl)pyrimidine and 2,2‐bis‐(4,6‐dichloropyrimidin‐2‐yl)dimethylmalonate. Structural studies using nmr, ir and uv spectroscopy indicate that for the former two compounds in basic solvent, an equilibrium exists between the keto forms and resonance‐stabilized enolate ions.
1H Nmr stuctural analysis of N3′‐dialkylaminoethyl derivatives from azabicyclospirohydantoins
Authors: Trigo G. G. , Espada M. , Gáalvez E. 
Published: March 2009

AbstractBased on the data from 1H nmr spectra, the structure and spatial conformation of the N3′‐β‐dimethyl and diethylaminoethyl derivatives from 3‐alkyl‐3‐azabicyclo[3.2.1]octane‐8‐spiro‐5′‐hydantoins and 3‐alkyl‐3‐azabicyclo[3.3.1]nonane‐9‐spiro‐5′‐hydantoins are established. The monosubstitution on the imide nitrogen atom has also been confirmed.
The reaction of alkylpyrazine anions with some electrophiles. Synthesis of 1,2‐bis(2‐pyrazyl)ethanes
Authors: Houminer Yoram , Sanders Edward B. 
Published: March 2009

AbstractThe reaction of alkylpyrazine anions with iodine, 1,2‐dibromoethylene or oxygen gives 1,2‐bis‐(2‐pyrazyl)ethanes.
Proton spin‐lattice relaxation studies. N‐aryl‐1‐isoindolinones
Authors: Khadim Mohammad A. , Colebrook Lawrence D. , Hall Laurance D. 
Published: March 2009

AbstractProton spin‐lattice relaxation rates (R1 values) have been measured, at 270 MHz, for a series of N‐aryl isoindolinones. A normalization procedure has been used to enable comparison of R1 values in different compounds by minimizing the effects on relaxation rates of changes in motional correlation times accompanying changes in substitution patterns. A substantial (4.3‐fold) dynamic range of R1 values has been observed, and individual values have been correlated with the molecular environments of the nuclei. There is evidence for an interring relaxation process.
Some fused‐ring succinimides as potential anticonvulsants
Authors: Campaigne E. , Yodice Richard 
Published: March 2009

AbstractThe syntheses of two compounds, which are fused‐ring succinimides, prepared as potential anticon‐vulsants, are described. The compounds are 3,4,5,6‐tetrahydro‐7‐methyl‐6‐oxoindeno[7,1‐bc]thiepin‐4a,5‐(2H)dicarboximide and 6,7,8,9‐tetrahydro‐2‐oxo‐1H‐benz[cd]azulene‐1,9a‐(2H)dicarboximide. The spirodioxolane of the latter compound was also prepared by ketalization.
Synthesis and photocyclization of some 4‐(5)arylethenylimidazoles
Authors: Lindgren Gerd , Stensiö Karl‐Erland , Wahlberg Kerstin 
Published: March 2009

AbstractThe synthesis of eleven 4‐(5)arylethenylimidazoles and their separation into cis and trans isomers is described. Ir, uv, nmr, and mass spectrometric data of the compounds are given. The photocyclization of the unsubstituted and p‐substituted compounds is reported.
Photoelectron spectroscopy of heterocycles. Azaindenes and azaindolizines
Authors: Kovać B. , Klasinc L. , Stanovnik B. , Tišler M. 
Published: March 2009

AbstractThe HeI photoelectron (PE) spectra of indole (1), benzimidazole (2), indazole (3), 3‐chloro‐indazole (4), imidazo[1,2‐b]pyridazine (5), 6‐chloroimidazo[1,2‐b]pyridazine (6), 2‐phenyl‐imidazo[1,2‐b]pyridazine (7), 2‐phenyl‐6‐chloroimidazo[1,2‐b]pyridazine (8), tetrazolo[1,2‐a]‐pyridine (9) and 8‐cyanotetrazolo[1,5‐a]pyridine (10) have been recorded. The spectra of 2–10 are of special interest for studying lone pair interactions. The assignment of the PE spectra submitted here, conjointly with the electronic structure of the studied compounds is discussed on the basis of molecular orbital calculations.
Photochemical synthesis of heteroatom‐containing polycyclic aromatic compounds
Authors: Maruyama Kazuhiro , Otsuki Tetsuo , Mitsui Kiichiro , Tojo Masahiro 
Published: March 2009

AbstractAnthra[2,1‐b]furan, anthra[2,1‐b]benzo[d]furan, anthra[2,1‐b]thiophene, anthra[1,2‐b]thiophene, anthra[2,1‐b]benzo[d]thiophene, anthra[2,1‐b]pyrrole and naphtho[2,3‐c]carbazole derivatives were synthesized in fairly good yields by a one‐pot photocycloaddition reaction of 2,3‐disubstituted 1,4‐naphthoquinone with 1,1‐diarylethylene. This is the first reported synthesis of these aromatic compounds.
New macrocyclic polyethers with remote binding sites
Authors: Rebek J. , Wattley R. V. 
Published: March 2009

AbstractThe synthesis and binding properties of new macrocyclic polyethers are described. These systems incorporate 2,2′‐bipyridyl functions in such a fashion that binding of metal nuclei can occur at either the macro‐cycle or the bipyridyl function. Evidence is presented that binding of alkali metals occurs at the crown ether cavity while binding of transition metals occurs at the bipyridyl function. Simultaneous binding of two different metals is interpreted in terms of electronic and allosteric effects.
Selenium‐containing pancreatic imaging agents. Synthesis of β‐2‐ and β‐3‐selenienylalanine
Authors: Frejd T. , Gronowitz S. , Davis M. A. , Sadeh T. 
Published: March 2009

AbstractSelenophene‐alanines, labelled with γ‐emitting selenium‐75, are potential diagnostic agents for disorders of the pancreas. Two of the positional isomers of selenienyl‐alanine were synthesized, namely 2‐selenienylalanine [2‐amino‐3‐(2‐selenienyl)propanoic acid] (88% yield) and 3‐selenienylalanine [2‐amino‐3‐(3‐selenienyl)propanoic acid] (65% yield). Both amino acids were prepared from the known chloromethyl selenophenes (2‐ and 3‐) by reaction with diethyl acetamidomalonate and subsequent hydrolysis. The method employed was found to be more productive than others which were tried.
Oxidation of 3,4‐disubstituted isoxazolin‐5‐ones
Authors: Beccalli Egle M. , Marchesini Alessandro , Gioia B. 
Published: March 2009

AbstractThe oxidation of 3,4‐disubstituted isoxazolin‐5‐ones with active manganese dioxide leads to the formation of C‐C and/or C‐N linked coupling products.
Heteroatomic chains and their products of cyclisation. IV. t‐butyl‐2‐phthalimido‐2‐(3,6‐dihydro‐1,3‐2H‐thiazine‐2‐yliden)‐acetates substituted in position 5 by a functional group
Authors: Duguay Guy , Guémas Jean‐Pierre , Meslin Jean‐Claude , Pradère Jean‐Paul , Reliquet Françoise , Reliquet Alain , Tea‐Gokou Célestin , Quiniou Hervé , Rabiller Claude 
Published: March 2009

AbstractSubstituted N′‐thioacetylformamidines, readily enthiolized, exist in fact in the form of zwitterions 8 with the transfer of the mobile hydrogen on the nitrogen N′. These zwitterions under (4 + 2) cyclocondensation with dienophiles. The dihydrothiazines formed (10) are possible interesting intermediates in the synthesis of cephems and cephalosporin analogs.
The insertion and extrusion of heterosulfur bridges. XI. Desulfurizations of condensed thiophenes by means of methanol and a molybdena catalyst
Authors: Klemm L. H. , Karchesy Joseph J. , Lawrence Ross F. , Wang Pih 
Published: March 2009

AbstractDesulfurizations of 2‐methyl‐ (1b), 4‐methyl‐ (1c), and 4,6‐dimethyldibenzothiophenes (1d), benzo[b]thiophene (2), and benzo[b]naphtho[2,1‐d]thiophene (5) were effected by means of methanol and a sulfided CMA catalyst [a mixed oxide of Co(II), Mo(VI), and Al(III)] at 450°. Desulfurization was accompanied by processes of demethylation and ring hydrogenation in the case of 1d and by both methylation and demethylation in the cases of 1b and 1c. Compound 2 gave ethylbenzene (80%), while 5 produced 2‐phenylnaphthalene (69%).
Chemical behaviour of 1,4‐benzoxazine
Authors: Chioccara Francesco , Prota Giuseppe , Novellino Ettore 
Published: March 2009

AbstractThe attempted synthesis of 2H‐1,4‐benzoxazine, which is unreported in the literature, gives a mixture of polymeric aldolization products. The major product, isolated in crystalline form, is formulated as the cyclic trimer 5.
Studies on reactive intermediates. Part I. An approach to the synthesis of 2‐phenyl‐7‐carbethoxy‐5H‐1,3,4‐thiadiazolo[2,3‐a]pyrimidin‐5‐one
Authors: Daneshtalab M. , Motamedi K. 
Published: March 2009

Abstract2‐Phenyltetrazolo[4,5‐a]‐1,3,4‐thiadiazole (4), in its azido form, reacted with diethyl fumarate and diethyl maleate to give 2‐phenyl‐7‐carbethoxy‐5H‐1,3,4‐thiadiazolo[2,3‐a]pyrimidin‐5‐one (5). To assign the structure of compound 5, 2‐phenyl‐5‐carbethoxy‐7H‐1,3,4‐thiadiazolo[2,3‐a]pyrimidin‐7‐one (6) was prepared from the reaction of 2‐amino‐5‐phenyl‐1,3,4‐thiadiazole (7) with diethylacetylene dicarboxylate. Physical properties and spectral data of compound 6 were different from compound 5. Theoretical and experimental aspects are discussed.
An improved synthesis of 3,5‐disubstituted isoxazoles and pyrazoles from C(α),O‐dilithiooximes and C(α),N‐dilithiophenylhydrazones
Authors: Fulmer Tammy D. , Dasher Lisette P. , Bobb Bonni L. , Wilson Jana D. , Sides Kimberly L. , Beam Charles F. 
Published: March 2009

AbstractC(α),O‐Dilithiooximes and C(α),N‐dilithiophenylhydrazones were prepared using an excess of lithium diisopropylamide (1:3). Condensation with esters followed by acid cyclization gave isoxazoles and pyrazoles.
Discrimination of the geometrical isomers of 2,3‐, 2,5‐, and 2,6‐dimethylpiperazines based on 1 HNmr spectral data
Authors: Tsutsui Mayumi , Watanabe Tokuhiro , Ohta Akihiro , Takizawa Kayoko 
Published: March 2009

Abstract1 H‐Nmr spectra of cis and trans isomers of 2,3‐, 2,5‐, and 2,6‐dimethylpiperazines were taken at various temperatures. The spectra of geometrical isomers bearing the ae or ea dimethyl groups showed broadening at lower temperatures. It was clarified that the measurement of the spectra at lower temperatures is useful for the discrimination of the geometrical isomers of dimethylpiperazines.
The photolysis of the l‐cycloalkoxy‐5‐chloro‐1,2,3‐benzotriazole system
Authors: Feld W. A. , Servé M. P. 
Published: March 2009

AbstractThree l‐cycloalkoxy‐5‐chloro‐1,2,3‐benzotriazoles were photolyzed at 254 nm. The major photolytic pathway yielded the corresponding cyclic ketone and 4,4′‐dichloroazobenzene.
Mononuclear heterocyclic rearrangements 5. Kinetic Investigation of the behaviour of (e)‐ and (z)‐phenylhydrazones of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole in benzene. Isomerization and rearrangement
Authors: Frenna Vincenzo , Vivona NicolÓ , Spinelli Domenico , Consiglio Giovanni 
Published: March 2009

AbstractThe kinetic behaviour of the geometrical isomers I‐E and I‐Z of the title compound in the presence of piperidine in benzene has been investigated. The kinetic results suggest that I‐Z rearranges directly into 2,5‐diphenyl‐4‐benzoylamino‐1,2,3‐triazole (II), whereas I‐E probably rearranges only through the intermediate I‐Z formed by isomerization. All the reactions studied are piperidine‐catalyzed.