bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectral studies of some substituted arylthiobenzo[f]quinolines
Authors: Bahuguna R. P. , Joshi Y. C. , Dobhal M. P. , Pande R. K. , Joshi B. C. 
Published: March 2009

AbstractSynthesis and spectral studies (ir, 1H nmr, ms) of 1‐ and 3‐substituted arylthiobenzo[f]quinolines (IIIa‐IIIc, IVa‐IVc) obtained through nucleophilic displacement of the corresponding halobenzo[f]quinoline by various thiols (a‐c) were done.
Reactions of 3‐acetyltropolone and its methyl ethers with aminoguanidine
Authors: Jin Zhong‐Tian , Imafuku Kimiaki 
Published: March 2009

Abstract3‐Acetyltropolone (1) reacted with aminoguanidine to afford its guanylhydrazone (3). The reaction of 3‐acetyl‐2‐methoxytropone (2a) gave 4‐methyl‐1(2H)‐phthalazinone (5), while the reaction of 7‐acetyl‐2‐methoxytropone (2b) gave its guanylhydrazone (6) and 3‐methyl‐1,8‐dihydrocycloheptapyrazol‐8‐one (4). The guanylhydrazones (3 and 6) were easily cyclized to 4 by heating in acetic acid.
Synthesis and evaluation of AChE inhibitory activity of 5,6‐diaryl‐1,2,4‐triazinyloxyacetyl‐4‐substituted thiosemicarbazides, triazoles and N‐benzylidene derivatives
Authors: Sen Gupta Anil K. , Hajela Kanchan , Bhattacharya Tapas , Ahmad Shakeel , Shanker Kripa 
Published: March 2009

AbstractA series of 1,2,4‐triazinyl thiosemicarbazides, triazoles and N‐benzylidene derivatives have been synthesized by condensation of 5,6‐diphenyl‐1,2,4‐triazin‐3‐yloxyacetyl hydrazine with aromatic aldehydes and aryl isothiocyanates. Subsequent ring closure of thiosemicarbazides yielded the triazoles. All the compounds were subjected to in vitro testing of cholinesterase inhibitory action. Percentage inhibition was found to be moderate to good in a few of the compounds.
Interpretation of the 13C NMR spectrum of physostigmine
Authors: Nieminen Antti O. K. , Haataja Helena , Rautio Marjatta , Rahkamaa Erkki 
Published: March 2009

AbstractThe 25.1 MHz 13C nmr spectrum of physostigmine in deuteriochloroform has been reanalysed with the aid of high resolution proton coupled spectrum and selective proton irradiation experiments. In addition to unambiguous assignment the analysis yielded values for carbon‐proton coupling constants.
Quinazolines and 1,4‐benzodiazepines. XCIII. Synthesis of imidazo[1,5‐a][1,4]benzodiazepines from nitrooximes
Authors: Walser A. , Fryer R. Ian 
Published: March 2009

AbstractThe displacement of the nitro group in nitrooximes by other nucleophiles was used to prepare various 2‐(hydroxyimino)methyl‐ and 2‐(methoxyimino)methyl‐1,4‐benzodiazepines. These compounds were converted to imidazo[1,5‐a][1,4]benzodiazepines bearing a tertiary amine, methoxy or thiomethyl group in the 3‐position.
Synthesis of (1‐substituted piperidin‐4‐yl)‐1H‐benzimidazoles and (1‐substituted piperidin‐4‐yl)‐3,4‐dihydroquinazolines as possible antihypertensive agents
Authors: Obase Hiroyuki , Takai Haruki , Teranishi Masayuki , Nakamizo Nobuhiro 
Published: March 2009

AbstractStructural modifications of 4‐piperidylbenzimidazolinones (I) by replacing the benzimidazolinone group with other heterocycles (2‐cyanoamino, 2‐ethoxy, and 2‐methylbenzimidazole and 2‐cyanoamino‐3,4‐dihydroquinazoline) has been made and a number of new piperidines (II) were synthesized as potential antihypertensive agents.
Reactions of α‐ketohydrazidoyl halides with some heterocyclic amines. Facile synthesis of arylazo derivatives of fused heterocycles with a bridgehead nitrogen atom
Authors: Abdelhamid Abdou O. , Hassaneen Hamdi M. , Shawali Ahmad S. , Párkányi Cyril 
Published: March 2009

AbstractArylazo derivatives of imidazo[2,1‐b]thiazoles, imidazo[1,2‐b]pyrazoles, imidazo[1,2‐b]‐s‐triazoles, imidazo[1,2‐a]pyrimidines, and imidazo[1,2‐a]pyridines were obtained in good yields from α‐keto hydrazidoyl halides and 2‐aminothiazole, 5‐aminopyrazole, 5‐aminotriazole, 2‐aminopyrimidine, and 2‐aminopyridine, respectively (cf. Tables I and II). The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectra, and alternate synthesis wherever possible.
Carbocyclic analogs of anhydrothymidines
Authors: Shealy Y. Fulmer , O'Dell C. Allen , Thorpe Martha C. , Coburn William C. 
Published: March 2009

AbstractThe carbocyclic analog of thymidine (C‐Thymidine, 2) was converted to the analog of 3′‐(O‐methanesulfonyl)‐5′‐O‐tritylthymidine, which was cyclized in alkaline solution or with 1,5‐diazabicyclo[5.4.0]undec‐5‐ene (DBU) to the carbocyclic analog of 5′‐O‐trityl‐2,3′‐anhydrothymidine (6). Hydrolysis of the latter compound produced the carbocyclic analog of all‐cis‐thymidine. C‐Thymidine was also converted to the carbocyclic analog of 3′‐O‐acetyl‐2,5′‐anhydrothymidine (12) by treating the 5′‐O‐methanesulfonyl analog with DBU. Hydrolysis of the anhydro derivative gave back C‐Thymidine. The carbocyclic analog (3) of 3′‐deoxy‐2′‐hydroxythymidine was converted similarly to the corresponding 2,2′‐anhydrothymidine (15) and 2,5′‐anhydrothymidine (21) analogs. As expected, C‐5′‐O‐trityl‐2,2′‐anhydrothymidine formed more readily than did the 2,3′‐anhydrothymidine analog. Hydrolysis of these 2,2′‐ and 2,5′‐anhydrothymidine analogs gave, respectively, the carbocyclic analog of all‐cis‐3′‐deoxy‐2′‐hydroxythymidine and 3.
Synthesis of 7‐phenylpyrimido[5,4‐d][1]benzazepin‐2‐ones
Authors: Chen Wen‐Yean , Gilman Norman W. 
Published: March 2009

AbstractThe syntheses of the 7‐phenylpyrimido[5,4‐d][1]benzazepin‐2‐ones 3, 4, and 5 are described. The 7‐phenyl group was introduced by phenylation of the lactam nitrogen in 10, 13 and 16 respectively. One of these compounds, 5, showed moderate activity as a CNS agent.
Pyrido[2,1‐d][1,5]benzoxazepin — ein neues tricyclisches heteroringsystem
Authors: Bartsch Herbert , Schwarz Otto , Völlenkle Horst 
Published: March 2009

AbstractDie Synthese and Strukturauflärung eines neuen tricylischen Heteroringsystems werden beschrieben. Die Struktur wurde durch Röntgenstrukturanalyse aufgeklärt.
Synthesis of substituted 2H[1]benzopyrans from coumarins and chromones
Authors: Alberola A. , Ortega A. González , Pedrosa R. , Bragado J. L. Pérez , Rodríguez Amo J. F. 
Published: March 2009

AbstractA convenient route to substituted 2H[1]benzopyrans is described in which trialkylaluminium compounds are added to coumarins or chromones and the resultant Z‐2‐(3‐hydroxy‐1‐propenyl)phenols are converted by thermal cyclization in the presence of silica gel to 2H[l]benzopyrans.
A new synthesis of 3‐amino‐1‐aryl‐2‐pyrazolin‐5‐ones
Authors: Hyatt John A. , Maggiulli Cataldo A. , French Stephen E. 
Published: March 2009

AbstractReaction of ethyl 3‐nitropropionate with aryldiazonium chlorides in basic medium yields ethyl 3‐nitro‐3‐(arylhydrazono)propionates. These α‐nitrohydrazones are converted by catalytic hydrogenation to 3‐amino‐1‐aryl‐2‐pyrazolin‐5‐ones, probably via cyclization of intermediate amidrazones produced in situ. This appears to be the first route to the title compounds that does not use a substituted phenyl hydrazine intermediate and offers advantages in the preparation of pyrazolinones bearing electron‐rich aryl rings.
New reactions of deoxyvasicinone
Authors: Dunn A. D. , Guy E. L. M. , Kinnear K. I. 
Published: March 2009

AbstractDeoxyvasicinone 1 was shown to react at the 3 position of the pyrrolidine ring with chloroformate esters and benzoyl choloride. Deuterium exchange at this site is also reported.
Unsymmetrically substituted furoxans. VIII. Chloromethylfuroxans
Authors: Calvino R. , Gasco A. , Menziani E. , Serafino A. 
Published: March 2009

AbstractThe two isomeric chloromethylfuroxans have been prepared. Their structures, thermal equilibration and reaction toward thiophenoxide ion are discussed. Kinetics of the 4‐methyl — 3‐methyl isomer thermal conversion are also reported.
Condensation of 2,4(3H,5H)‐furandione with heteroaromatic aldehydes
Authors: Schmidt Diane Grob , Zimmer Hans 
Published: March 2009

Abstract2,4(3H,5H)‐Furaridione, 1, condenses with heteroaromatic aldehydes in the presence of concentrated hydrochloric acid to yield 3‐(heteroarylmethylene)‐2,4(3H,5H)‐furandiones, 4. The condensation of 1 with acid sensitive aldehydes, including 2‐furanacroleine and N‐methylpyrrole‐2‐carboxaldehyde proceeded well with 1 as the sole proton source. The E/Z ratio of type 4 compounds was determined by 1H‐nmr spectroscopy.
Reissert compounds and their open‐chain analogs in organic synthesis
Authors: Cooney John V. 
Published: March 2009

AbstractReactions of major synthetic interest employing Reissert compounds (1, 2‐dihydro‐1‐acyl‐2‐cyanoquinolines and 1, 2‐dihydro‐2‐aqyl‐1‐cyanoisoquinolines) and related heterocyclic species are surveyed. The chemistry of open‐chain analogs of Reissert compounds (i.e., derivatives of N‐acyl‐α‐aminoacetonitriles) is described and compared with conventional Reissert compounds.
Investigation of the structure and 13C NMR spectrum of 5‐phenylbarbituric acid
Authors: De Meester Patrice , Chu Shirley S. C. , Jovanovic Misa V. , Biehl Edward R. 
Published: March 2009

AbstractCrystals of 5‐phenylbarbituric acid, 2, are monoclinic, space group C2/c. There are 8 molecules in the unit cell of dimensions a = 20.218(3), b = 7.477(1), c, = 12.443(2), β = 111.54° and V = 1749.6(4) Å3. Full‐matrix least‐squares refinement has reached R = 0.039. This is the first barbiturate reported to exist in the enol form in the solid state. There is extensive hydrogen bonding between adjacent molecules which gives rise to very dense crystals. The 13C‐nmr spectroscopy shows that 2 exists in both enol and keto forms in DMSO solution.
Proton‐ionizable crown compounds. 3. Synthesis and structural studies of macrocyclic polyether ligands containing a 4‐pyridone subcyclic unit
Authors: Bradshaw Jerald S. , Nakatsuji Yohji , Huszthy Peter , Wilson Bruce E. , Dalley N. Kent , Izatt Reed M. 
Published: March 2009

AbstractNew proton‐ionizable macrocyclic polyether ligands containing the 4‐pyridone subcyclic unit have been prepared by reacting 4‐THP blocked‐2,6‐pyridinedimethanol with various oligoethylene glycol ditosylates. The 18‐crown‐6 ligand containing the 4‐pyridone subcyclic unit, 4, forms stable complexes with alkali metal and organic ammonium cations. The crystal structure of 4 proves the 4‐pyridone structural unit. The crystal structure of the potassium thiocyanate complex of 4 is also reported and shows the complex to contain the 4‐hydroxypyridine unit.
Fused s‐triazino heterocycles. XIII. 1,3,7,10,11c‐Pentaazabenz[de]‐anthracene and 1,3,7,10,11,13,13d‐heptaazabenz[de]cyclopenta[H]‐anthracene, two new ring systems
Authors: Shaw John T. , Acciai Guy F. , Babin James E. , Sensenig Lori A. 
Published: March 2009

AbstractThe synthesis of the title compounds 5a‐c and 6a‐c is described using, 2,6‐diaminopyridine as starting material. The key intermediates are 2‐t‐butyl‐4‐cyano‐5(2‐dimethylaminoethenyl)‐1,3,6,9b‐tetraazaphenalene 4 and 10‐amino‐2‐t‐butyl‐10,11‐dihydro‐11‐imino‐1,3,7,10,11c‐pentaazabenz[de]anthracene 5c.
Aminosäuren als synthesebausteine von pyrrolo[1,2‐a]‐ und [2,3‐d]anellierten heterobicyclen
Authors: Sinambela James M. , Zimmermann Werner , Roth Hermann J. , Eger Kurt 
Published: March 2009

AbstractEs wird über die Möglichkeit berichtet, natürlich vorkommende Aminosäuren als bifunktionelle Bausteine zur Heterocyclensynthese einzusetzen.
Mutagenic heterocyclic nitrogen compounds related to protein pyrolysates. V. Electron impact fragmentation of L‐glutamic acid and related dipyrido[1,2‐a:3′,2′‐d]imidazoles
Authors: Saint‐Ruf Germain , Loukakou Bernard , Hebert Eric , Keravis GÉRard 
Published: March 2009

AbstractSix dipyrido[1,2‐a:3′,2′d]imidazole derivatives related to glutamic acid pyrolysates have been studied by mass spectrometry. The data indicate that there are certain ions which are characteristic of the fragmentation of this family of compounds under electron impact. These compounds should thus be amenable to analysis if they were produced during the combustion of foods. In addition, electronolysis of L‐glutamic acid was also studied: the fragmentation pattern of the latter has shown the formation of some known dipyridoimidazoles for temperatures higher than 100°. Similarities between pyrolysis and electronolysis of this acid are discussed.
Synthesis of halogenated hydrazone derivatives and their applicability in the preparation of 4‐chloropyrazoles
Authors: Barluenga José , Iglesias M. José , Muñiz Laudina , Gotor Vicente 
Published: March 2009

AbstractReaction of hydrazonic derivatives 1 with N‐chlorosuccinimide affords monohalogenated hydrazones 3 with nearly quantitative yields. When 3 is treated with mineral acids or trifluoroacetic acid 4‐chloropyrazoles are isolated.
Synthesis of lipophilic crown ethers with pendant carboxylic acid groups
Authors: Czech Bronislaw P. , Czech Anna , Son Byungki , Lee Han Koo , Bartsch Richard A. 
Published: March 2009

AbstractSynthetic routes to thirteen highly lipophilic crown ether carboxylic acids are described. Seven contain 12–15‐membered crown ether units with four ring oxygens and are designed for lithium ion complexation. Three others possess large ring 24‐crown‐8, 27‐crown‐9, and 30‐crown‐10 units. Six new hydroxymethyl crown ethers are prepared as synthetic intermediates.
Amination of 3,6‐dinitro‐1,8‐naphthyridines
Authors: Wozniak M. , Plas C. Van Der 
Published: March 2009

AbstractTreatment of 2‐amino‐3,6‐dinitro‐1,8‐naphthyridines with liquid ammonia/potassium permanganate gives 2,4‐diamino‐3,6‐dinitro‐1,8‐naphthyridine. From 2‐ethoxy‐3,6‐dinitro‐1,8‐naphthyridine a mixture of 4‐amino‐and 5‐amino‐3,6‐dinitro‐1,8‐naphthyridine was obtained. 2‐Chloro‐3,6‐dinitro‐1,8‐naphthyridine afforded a mixture of four compounds i. e. 2,4‐ and 2,5‐diamino‐3,6‐dinitro‐1,8‐naphthyridine and 2‐chloro‐5‐amino‐3,6‐dinitro‐1,8‐naphthyridine and 2‐amino‐3,6‐dinitro‐1,8‐naphthyridine. A study on covalent amination has shown that 4‐amino‐2‐ethoxy‐3,6‐dinitro‐1,8‐naphthyridine undergoes covalent amination at C‐5, whereupon in this adduct amino‐deethoxylation takes place. In a similar way, 2‐chloro‐ and 2‐ethoxy‐5‐amino‐3,6‐dinitro‐1,8‐naphthyridine give covalent amination at C‐4.
Furopyridines. V. A simple synthesis of furo[2,3‐c]pyridine and its 2‐and 3‐methyl derivatives
Authors: Morita Hiroyuki , Shiotani Shunsaku 
Published: March 2009

AbstractA simple synthesis of furo[2,3‐c]pyridine and its 2‐ and 3‐methyl derivatives from ethyl 3‐hydroxyisonicotinate (2) is described. The hydroxy ester 2 was O‐alkylated with ethyl bromoacetate or ethyl 2‐bromopropionate to give the diester 3a or 3b. Cyclization of compound 3a afforded ethyl 3‐hydroxyfuro [2,3‐c]pyridine‐2‐carboxylate (4) which was hydrolyzed and decarboxylated to give furo[2,3‐c]pyridin‐3(2H)‐one (5a). Cyclization of 3b gave the 2‐methyl derivative 5b. Reduction of 5a and 5b with sodium borohydride yielded the corresponding hydroxy derivative 6a and 6b, respectively, which were dehydrated with phosphoric acid to give furo[2,3‐c]pyridine (7a) and its 2‐methyl derivative 7b. 4‐Acetylpyridin‐3‐ol (8) was O‐alkylated with ethyl bromoacetate to give ethyl 2‐(4‐acetyl‐3‐pyridyloxy) acetate (9). Saponification of compound 9, and the subsequent intramolecular Perkin reaction gave 3‐methylfuro[2,3‐c]pyridine (10). Cyclization of 9 with sodium ethoxide gave 3‐methylfuro[2,3‐c]pyridine‐2‐carboxylic acid, which in turn was decarboxylated to give compound 10.
The synthesis and proton nuclear magnetic resonance study of some nitro‐ and amino‐unsymmetrically meta‐substituted tetraphenylporphyrins
Authors: Sun Yizhen , Martell Arthur E. , Tsutsui Minoru 
Published: March 2009

AbstractProcedures for the synthesis of new partially‐substituted mesotetraphenylporphyrins (TPP's) are described. The 5‐(3‐nitrophenyl)‐10,15,20‐triphenylporphyrin is the primary product from a 1:2:3 molar ratio of m‐nitrobenzaldehyde, benzaldehyde and pyrrole. The crude reaction product also contained TPP, 5,10‐bis‐(3‐nitrophenyl)‐15,20‐diphenylporphyrin, 5,15‐bis(3‐nitrophenyl)‐10,20‐diphenylporphyrin, and 5,10,15‐tris‐(3‐nitrophenyl)‐20‐phenylporphyrin. The crude mixture of m‐nitrophenylporphyrins was reduced to a mixture of the corresponding amino derivatives, which was separated into TPP, 5‐(3‐aminophenyl)‐10,15,20‐triphenylporphyrin, 5,10‐bis(3‐aminophenyl)‐15,20‐diphenylporphyrin, and 5,15‐bis(3‐aminophenyl)‐10,20‐diphenylporphyrin. The products were characterized by uv‐visible and ir spectrophotometry, and by high resolution nmr spectroscopy and mass spectroscopy.
A modified synthesis of 4‐chloromethylthiazoles
Authors: Marzoni Gifford 
Published: March 2009

AbstractA two‐reaction synthesis of 2‐substituted‐4‐chloromethylthiazoles from thioamides and 1,3‐dichloroacetone is reported. The first step, cyclization to a 2‐substituted‐4‐chloromethyl‐4‐hydroxythiazoline is carried out in the presence of bicarbonate in an aprotic solvent. Dehydration of this intermediate to a 2‐substituted‐4‐chloromethylthiazole is accomplished by reaction with thionyl chloride, sulfuryl chloride, phosphoryl chloride, phosphorus trichloride or phosphorus pentachloride. Substituents on the thioamide, such as amino, alkyl, or aryl, are shown not to affect the success of the reaction. As a trend, alkylthioamides give slightly better yields of 4‐chloromethylthiazoles than do arylthioamides. The yields of 4‐chloromethylthiazoles prepared using this procedure are comparable to the yields obtained using acid catalyzed procedures.
Some novel halogenated phenazine derivatives
Authors: Twomey Dermot 
Published: March 2009

Abstract3‐Amino‐10‐aryl‐2‐arylimino‐2,10‐dihydrophenazines 1 undergo iodination in the 4‐position of the phenazine nucleus yielding compounds which are identical with those obtained by oxidation of appropriate N‐aryl‐o‐phenylenediamines with sodium iodate in the presence of acid. Bromination also takes place in this position but a second bromine atom enters the para‐position of the arylimino moiety. The isomeric 10‐aryl‐3‐aryl‐amino‐2,10‐dihydro‐2‐iminophenazines 2 yield unstable iodo‐derivatives but undergo bromination in the 1‐and 4‐position of the phenazine nucléus and in the ortho‐ and para‐positions of the arylamino substituent. Preliminary chlorination experiments indicate that the substitution pattern is analogous to that established for the brominated products. The removal of bromine and iodine from the phenazine ring by reaction with a primary or secondary amine and their replacement by hydrogen rather than by the amine residue is also recorded.
A galactoside derivative of a nitrosoisocytosine inhibitor of dihydropteroate synthase: Synthesis and biological evaluation
Authors: Lever O. William , Hyman Clifton , Ray Paul H. , Ferone Robert , Kelsey John E. 
Published: March 2009

AbstractThe synthesis of the O‐β‐D‐galactosyl derivative 3 of the dihydropteroate synthase inhibitor 6‐(3‐(4‐hydroxyphenoxy)propylamino)‐5‐nitrosoisocytosine (2) was accomplished through coupling of N‐(3‐(4‐hydroxyphenoxy)propyl)phthalimide (4) with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐galactopyranosyl bromide followed by complete deblocking of the resulting β‐glycoside 9 with hydrazine and then methanolic ammonia to provide amine 10, and subsequent condensation of 10 with 6‐methylthio‐5‐nitrosoisocytosine (11). Glycoside 3 inhibited the synthase with moderate potency (I50 = 11 μM) but did not exhibit antibacterial activity.
Reaction of 3‐amino‐5,6‐dimethyl‐1,2,4‐triazine with electrophiles
Authors: Suzuki Toshinobu , Okazaki Masahiko , Mitsuhashi Keiryo 
Published: March 2009

AbstractThe title compound was reacted with four types of electrophiles and the respective reaction sites were investigated. The reaction with aryl isocyanates in the conventional way yielded the corresponding ureas. In the presence of triethylamine, the 3‐amino group was diacylated with acyl chlorides. On the other hand, in the cases with arylsulfonyl chlorides and p‐nitrobenzaldehyde under similar conditions, the methyl group at 5‐position was preferentially attacked to give arylsulfonylmethyl and p‐nitrostyryl derivatives, respectively.
Preparation of benzo[c][2,7]naphthyridin‐5(1H)‐ones as analogs of benzopyrano[3,4‐c]pyridin‐5‐one bronchodilators
Authors: Unangst Paul C. , Connor David T. , Carethers Mary E. , Schwender Charles S. , Brown Richard E. , Puchalski Chester 
Published: March 2009

AbstractA series of 2,3,4,6‐tetrahydro‐8,9‐dimethoxybenzo[c][2,7]naphthyridin‐5(1H)‐ones was prepared as potential anticholinergic bronchodilators. The naphthyridine ring system was constructed by cyclization of a 3‐amido‐4‐piperidone. Alkylation with alkylaminoethyl chlorides or reductive amination of an intermediate methyl ketone yielded the final target compounds.
Synthesis of 2‐aminomethyl‐1,10‐phenanthroline. A new chelating agent and versatile synthon for other chelating compounds
Authors: Engbersen J. F. J. , Koudijs A. , Joosten M. H. A. , van der Plas H. C. 
Published: March 2009

AbstractThe synthesis of 2‐aminomethyl‐1,10‐phenanthroline (4) from 1,10‐phenanthroline (1) is described. The reduction of 2‐cyano‐1,10‐phenanthroline (3) to 4 in the presence of 10% palladium on carbon in acetic acid under mild reaction conditions also proved to be a very efficient method for conversion of cyanopyridines to methylaminopyridines.
The photochemistry of α,β‐acetylenic ketones. II. Formation of furan derivatives
Authors: Nishio Takehiko , Nakata Hiroyuki , Omote Yoshimori 
Published: March 2009

AbstractThe photochemical reactions of α,β‐acetylenic ketones have been examined. Irradiation of 1‐p‐substituted phenyl‐2‐propyn‐1‐ones 2–4 in primary alcohols gave 2,5‐disubstituted furans 2a–4c. The formation of furans can be explained in terms of cyclization, followed by dehydration of the 1:1‐adduct of acetylenic ketone and alcohol, which was formed initially by hydrogen atom abstraction from alcohol by the excited acetylenic ketone. Irradiation of 1‐p‐tolyl‐2‐propyn‐1‐one (2) in ethanol‐d1 yielded 2‐methyl‐5‐p‐tolylfuran (2b) containing no deuterium. This result was consistent with a mechanism that involves hydrogen atom abstraction from alcohol by the carbon of triple bond rather than abstraction by carbonyl oxygen.
Structural effects on the rates of the ion molecule reactions of organic heterocycles
Authors: Scala A. A. , Caputo M. G. , Billings D. 
Published: March 2009

AbstractRate constants for proton transfer reactions of seven heterocyclic amines, eight heterocyclic ethers and propylene sulfide have been measured by photoionization mass specrometry. Rate constants for dimerization of four sulfides have also been measured. The measured rate constants have also been compared to the theoretical (ADO) rate constants. In all cases the ADO rate constants show only small variations with structure. In fact for the mono‐heterocycles all but one of the ADO rate constants are between 2.0 and 1.5 × 10−9 cc molec−1 sec−1. The observed rate constants show considerable dependence on chemical structure. The amines react faster than the oxides which in turn react faster than the sulfides. N‐Methyl substitution on pyrrolidine and piperidine lowers their rate constants by about a factor of two while, propylene oxide reacts eighteen percent faster than ethylene oxide. Examination of the variation in the observed rate constants as a function of ring size for each group of heterocycles indicates a distinct structure‐reactivity correlation although we have not attempted to rationalize this correlation. There is also a structure‐reactivity dependence observed in the six‐membered oxygen heterocycles having a second heteroatom O, NH, or S in the 4‐position. The rate constants increase with the electronegativity of the second heteroatom.
Base‐induced ring cleavage of 4‐functionalized‐3‐unsubstituted isoxazoles. Synthesis of 5‐aminoazoles and 4‐cyanoazoles
Authors: Alberola A. , Antolin L. F. , Gonzalez A. M. , Laguna M. A. , Pulido F. J. 
Published: March 2009

AbstractThe base‐induced ring cleavage of 4‐nitro‐(Ia), 4‐ethoxycarbonyl‐ (Ib) and 4‐acetyl‐5‐methylisoxazole (Ic) and the conversion of the resulting β‐cyanoenolates and β‐enaminonitriles into 5‐aminoazoles and 4‐cyanoazoles was studied.