bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of alkyl substituted 1,3,4‐oxadiazin‐6‐ones by the DCC induced cyclization of 2‐oxoalkanoic acid acylhydrazones
Authors: Padwa Albert , Eisenbarth Philipp 
Published: April 2009

AbstractA series of 2,5‐disubstituted 1,3,4‐oxadiazin‐6‐ones were prepared by treating syn‐2‐oxoalkanoic acid acylhydrazones with dicyclohexylcarbodiimide. The isomeric anti isomers produced acylureas when treated with DCC. The cycloaddition reaction of 5‐methyl‐2‐phenyl‐1,3,4‐oxadiazin‐6‐one with norbornene was studied and found to give a nitrogen deficient 1:1‐cycloadduct. The formation of the product can be rationalized in terms of a Diels‐Alder cycloaddition followed by nitrogen extrusion and cyclization of the resulting γ‐ketoketene intermediate.
Preparation and stereochemistry of 3‐phenacylidenephthalimidines
Authors: Howe Robert K. 
Published: April 2009

AbstractYields of 3‐phenacylidenephthalimidines are maximized and yields of phthalimide byproducts are minimized by use of acetic acid as the solvent in reactions of amines with 3‐phenacylidenephthalides. The 3‐phenacylidenephthalimidines are formed as E, Z mixtures, in which the E isomers predominate. A homonuclear NOE nmr experiment was employed to determined product stereochemistry.
Studies on 1,2,3‐triazoles. Part XI. A new entry to the benzopyrano[2,3‐D]‐1,2,3‐triazole system. Cyclization of 1‐benzyl‐5‐chloro‐4‐(2‐hydroxybenzoyl)‐1H‐1,2,3‐triazoles
Authors: Buckle Derek R. 
Published: April 2009

AbstractThe acylation of simple arenes such as benzene and alkylated benzenes with N‐protected 5‐chloro‐1H‐1,2,3‐triazole‐4‐carboxylic acid chlorides under Friedel‐Crafts conditions results in excellent yields of the corresponding ketones. Resorcinol dimethyl ethers undergo similar acylation reactions in somewhat lower yield with concomitant monodemethylation, and these derivatives undergo a facile base mediated cyclization to 9‐oxo‐3H,9H‐benzopyrano[2,3‐d]‐1,2,3‐triazoles.
Synthesis of spiro[3H‐indole‐3,2′‐tetrahydro‐1,3‐thiazine]‐2,4′(1H)‐diones
Authors: Rajopadhye Milind , Popp Frank D. 
Published: April 2009

AbstractThe title compounds have been prepared by the cyclocondensation of 3‐mercaptopropanoic acid with isat‐in‐3‐imines. The 1‐benzyl derivatives have been synthesized by simultaneously reacting 1‐benzylisatin, substituted anilines and 3‐mercaptopropanoic acid. Mannich condensation of the spiro thiazanones with secondary amines gave the corresponding 1‐aminomethyl derivatives.
Heterocyclic rearrangements. N,N‐diphenylhydrazones, oximes and O‐methyloximes of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole
Authors: Vivona Nicolò , Frenna Vincenzo , Buscemi Silvestre , Ruccia Michele 
Published: April 2009

AbstractThe behaviour of (E)‐ and (Z)‐N,N‐diphenylhydrazones and O‐Methyloximes of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole has been studied. When refluxed in benzene, or in dioxane‐water (1:1), the (Z)‐N,N‐diphenylhydrazone 8Z gave the indazole 11 or the substituted semicarbazide 12, respectively. The O‐methyloxime 14Z did not give any rearrangement. A criticism of the oximation reaction of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole is also reported.
Some intramolecular michael additions of adenine derivatives
Authors: Brahme Nanda M. , Smith Walter T. 
Published: April 2009

AbstractIn our attempts to prepare polymerizable derivatives of nucleic acid bases, we investigated the reaction of adenine (1) and 9‐(cyanoethyl)adenine (4) with acrylic anhydride and acryloyl chloride. Reactions of adenine with methyl acrylate and vinyl acrylate were also examined. The results show that these reactions are solvent dependent and the intermediate acryloyladenine 3 can undergo a facile intramolecular Michael reaction to form 7.
A new synthesis of 5,7‐dicarboxy‐2,1‐benzisoxazolin‐3‐one
Authors: Kim C. K. , Krasavage B. A. , Maggiulli C. A. 
Published: April 2009

AbstractCondensation of methyl 2‐isoxazolin‐5‐on‐3‐yl acetate (3) and 3‐(N,N‐dimethylamino)‐2‐ethoxycarbonylacrolein (6) gave 5‐ethoxycarbonyl‐7‐methoxycarbonyl‐2,1‐benzisoxazolin‐3‐one (7a). Simple hydrolysis of the diester 7a afforded 5,7‐dicarboxy‐2,1‐benzisoxazolin‐3‐one (7b).
Diels‐alder cycloadditions of diene‐substituted N‐ethoxycarbonyl‐2‐methyl‐1,2‐dihydropyridines with N‐phenylmaleimide
Authors: Krow Grant R. , Cannon Kevin C. , Carey James T. , Lee Yoon B. , Szczepanski Steven W. , Ramjit Harri G. 
Published: April 2009

AbstractThe ten possible substitution patterns for N‐Ethoxycarbonyl‐2‐methyl‐1,2‐dihydropyridines 5 in which one or two olefinic sites are alkyl substituted were synthesized and reacted with N‐phenylmaleimide 2 to provide cycloadducts 6. N‐Ethoxycarbonyl‐5,6‐cyclohexyl‐2‐methyl‐1,2‐dihydropyridine 51 provided the novel spirocycle 61.
Synthesis of some 7‐substituted 3‐chloro‐3,4‐dihydro‐1‐hydroxycarbostyrils by the reduction cyclization of α‐chloro‐β‐(4‐substituted‐2‐nitrophenyl)propionic acids
Authors: Mccord Tommy J. , Warner Michael R. , Shafer Paul L. , Disher Rose M. Davis , Davis Alvie L. 
Published: April 2009

AbstractA new method was developed for the synthesis of some 7‐substituted 3‐chloro‐3,4‐dihydro‐l‐hydroxycarbostyrils 3c‐g in which α‐chloro‐β‐(4‐substituted‐2‐nitrophenyl)propionic acids 2c‐g were reductively cyclized by catalytic hydrogenation over platinum‐on‐carbon sulfided catalyst. In particular, this method was applied to α‐chloro‐β‐(2‐nitrophenyl)propionic acids bearing 4‐methyl 2c, 4‐ethyl 2d, 4‐ethoxy 2e, 4‐(n‐butyl 2f and 4‐phenyl 2g substituents to afford good yields of the corresponding 7‐methyl 3c, 7‐ethyl 3d, 7‐ethoxy 3e, 7‐(n‐butyl) 3f, and 7‐phenyl 3g substituted 3‐chloro‐3,4‐dihydro‐l‐hydroxycarbostyrils. The various 4‐substituted α‐chloro‐β‐(2‐nitrophenyl)propionic acids 2c‐q were synthesized by reacting the in situ diazotized salts of the appropriate 4‐substituted‐2‐nitroanilines in aqueous acetone with acrylic acid in the presence of cuprous chloride and hydrochloric acid. All compounds prepared in this study were characterized by microanalytical and ir and nmr spectral data.
Fluorinated heterocyclic compounds. 4‐fluoro‐2‐pyridone
Authors: Leznoff Clifford C. , Svirskaya Polina I. , Yedidia Varda , Miller Jack M. 
Published: April 2009

AbstractThe uracil analog, 4‐fluoro‐2‐pyridone was synthesized by ether cleavage of 4‐fluoro‐2‐methoxypyridine with trimethylsilyl iodide. Improved procedures for the preparations of 2‐methoxypyridine N‐oxide hydrochloride and 2‐methoxy‐4‐nitropyridine N‐oxide are described.
Fluorinated heterocyclic compounds. 2. 2,4‐difluoro and 4‐amino‐2‐fluoropyrimidines, nucleoside base analogs
Authors: Svirskaya Polina I. , Yedidia Varda , Leznoff Clifford C. , Miller Jack M. 
Published: April 2009

AbstractNucleoside base analogs in which fluoro substituents replace the enolic hydroxy groups of uracil, thymine and cytosine have been prepared. Improved methods for the preparation and isolation of the known 2,4‐di‐fluoropyrimidine, 2,4‐difluoro‐6‐methylpyrimidine and the new 2,4‐difluoro‐5‐methylpyrimidine, 2‐fluoro‐4‐aminopyrimidine, 4‐fluoro‐2‐aminopyrimidine, and other alkylaminofluoropyrimidines are described.
A one‐step synthesis of 2‐methylthio‐6‐oxopyrimidine derivatives: Preparation of fused pyrimidinones
Authors: Hussain S. M. , El‐Barbary A. A. , Mansour S. A. 
Published: April 2009

AbstractCondensation of a ternary mixture of ethyl cyanoacetate, S‐methylisothiourea and aromatic aldehydes in pyridine afforded directly the 4‐aryl‐5‐cyano‐2‐methylthio‐6‐oxopyrimidines IV in good yields. Alkylation of IV with alkyl halides in alkaline medium yielded the 1‐alkyl derivatives V. The methylthio group in IV and V could be eliminated by aniline, hydrazine and phenylhydrazine and the corresponding 2‐anilino, VII, 2‐hydr‐azino, VIIIa,b, and 2‐phenylhydrazino, VIIIc,d, derivatives were obtained. Compounds VIIIa,b could be cyclised with nitrous acid to give the 3‐cyano‐4‐phenyltetrazolo[1,5‐a]pyrimidine‐2‐one (Xa) and the 1‐methyl analogue Xb, respectively. Some derivatives of VIII were prepared to help in elucidating the structures.
Reactions of ethyl 4‐chloro‐5‐pyrimidinecarboxylates with 2‐aminopyridine. Synthesis of 5H‐pyrido[1,2‐A]pyrimido[5,4‐e]pyrimidin‐5‐ones and 5H‐pyrido[1,2‐a]pyrimido[4,5‐d]pyrimidin‐5‐ones and rearrangement of the former to the latter
Authors: Kim Dong Han 
Published: April 2009

Abstract5H‐Pyrido[1,2‐a]pyrimido[5,4‐e]pyrimidin‐5‐ones IVa,b and 5H‐pyrido[1,2‐a]pyrimido[4,5‐d]pyrimidin‐5‐ones Va,b were synthesized from ethyl 4‐chloro‐5‐pyrimidinecarboxylate and 2‐aminopyridine. The former compounds were obtained directly upon heating the reactants in ethanol, and the latter were prepared by the fusion of ethyl 4‐(2‐pyridylamino)‐5‐pyrimidinecarboxylates obtained as minor products from the above reaction. The angular fused cyclic compounds, IVa,b were rearranged to the linear tricycles, Vb‐f upon heating with amines.
Polycyclic N‐hetero compounds. XIX. Synthesis of novel meso‐ionic benz[h]imidazo[1,2‐c]quinazoline and benzo[h]pyrrolo[1′,2′:3,4]imidazo[1,2‐c]quinazoline derivatives
Authors: Hirota Takashi , Katsuta Kimiko , Namba Tetsuto , Sasaki Kenji , Hayakawa Shõhei 
Published: April 2009

AbstractBenz[h]imidazo[1,2‐c]quinazolinium‐l‐olate (5) and benzo[h]pyrrolo[1′,2′:3,4]imidazo[1,2‐c]quinazolinium‐8‐olate (9) having novel meso‐ionic ring systems were synthesized by the reaction of N‐(5,6‐dihydrobenzo[h]‐quinazolin‐4‐yl)amino acids with acetic anhydride.
The chemistry of 3‐azaisotoic anhydrides. Synthesis and reactions of polyaza heterocycles
Authors: Coppola Gary M. , Fraser James D. , Hardtmann Goetz E. , Shapiro Michael J. 
Published: April 2009

AbstractThe preparation of a variety of N‐substituted 3‐azaisatoic anhydrides 3 and 8 is described. These anhydrides reacted with thiopseudoureas to give interesting bicyclic, tricyclic, and tetracyclic heterocycles many of which are new ring systems. One such heterocycle, the imidazo[1,2‐a]pyrido[2,3‐d]pyrimidine ring system, was studied further with respect to alkylation and reduction reactions. Alkylation of 12h occurred on the nitrogen in the central B ring, whereas, in the reduced species 33, alkylation took place in the C ring.The reaction of 3‐azaisatoic anhydrides with carbanions was also investigated. Reactions occur with anions generated from nitromethane, diethylmalonate, ethyl nitroacetate, ethyl isocyanate, and ethyl o‐fluorobenz‐oylacetate.
The 1,3,4‐oxadiazole moiety, a protective synthon for indirect radioiodination
Authors: Heindel Ned D. , Van Dort Marcian , Cahn Maurice , Schneider Richard , Burns H. Donald 
Published: April 2009

Abstract2‐(4‐Hydroxyphenyl)‐1,3,4‐oxadiazole can readily be iodinated/radioiodinated to 2‐(3,5‐diiodo‐4‐hydroxy‐phenyl)‐1,3,4‐oxadiazole which in a one‐step hydrolysis‐condensation serves as an indirect prosthetic moiety for iodination of carbonyl compounds.
Synthesis of the isomeric monomethyl derivatives of the novel naphtho[2′,1′:4,5]thieno[2,3‐c]quinoline ring system
Authors: Kudo Hirotaka , Castle Raymond N. , Lee Milton L. 
Published: April 2009

AbstractThe synthesis of the novel naphtho[2′,1′:4,5]thieno[2,3‐c]quinoline (11) ring system and four of the isomeric monomethyl derivatives is described.
Assignment of the 13C‐NMR spectrum of phenanthro[4,3‐A]dibenzothiophene through the utilization of two‐dimensional relayed coherence transfer and double quantum coherence spectroscopy
Authors: Musmar M. J. , Martin Gary E. , Gampe Robert T. , Lee Milton L. , Hurd Ralph E. , Tedjamulia Marvin L. , Kudo Hirotaka , Castle Raymond N. 
Published: April 2009

AbstractTotal assignment of the 13C‐nmr spectrum of the helical molecule phenanthro[4,3‐a]dibenzothiophene at 125.762 MHz is reported. Assignments were made by the combined application of 13C‐13C autocorrelated double quantum coherence and heteronuclear relayed coherence transfer (RELAY) experiments.
Synthesis of substituted, 2,2,5,5‐tetramethylpyrrolidin‐l‐oxyl spin labels–PH sensitivity studies
Authors: Mathew Abraham E. , Dodd John R. 
Published: April 2009

AbstractThe synthesis of derivatives of 2,2,5,5‐tetramethylpyrrolidine nitroxide spin labels aspH sensitive probes is reported. The data on thepH sensitivity studies of these compounds indicate that the amino group increases thepH sensitivity of a nitroxide to a greater degree than a cyano, carboxyl or amido group.
Benzofurano derivatives of coumarins as possible antifertility agents
Authors: Sinha Sunil , Tyagi Anil , Pandey R. K. , Joshi B. C. 
Published: April 2009

AbstractSynthesis and medicinal importance of 4‐methyl‐6‐nitro‐8,9,10,11‐tetrahydro‐2H‐benzofuro[2,3‐b]‐1‐benzo‐pyran‐2‐one (I), 4‐ethyl‐11‐nitro‐6,7,8,9‐tetrahydro‐2H‐benzofuro[3,2‐g]‐1‐benzopyran‐2‐one (II), and 6,7‐di‐hydro‐4,13‐dimethylbis‐1‐benzopyrano[6,7‐d:7′,6′‐d']‐2H,11H‐benzo[1,2‐b:3,4‐b']difuran‐2,11‐dione (III) is presented. The structures of these compounds were confirmed by elemental analysis and spectral studies.
Polycondensed heterocycles. I. Synthesis of 11‐oxo‐5H, 11H‐pyrrolo[2,1‐c][1,4]benzothiazepine, Derivative of a novel ring system
Authors: Nacci V. , Garofalo A. , Fiorini I. 
Published: April 2009

AbstractThe synthesis of the title compound 4 by cyclization of 1‐(2‐ethoxycarbonylthiobenzyl)pyrrole 9, prepared by treating with ethyl chloroformate the 1‐(2‐mercaptobenzyl)pyrrole 7 previously obtained by debenzylation of 1‐(2‐benzylthiobenzyl)pyrrrole 6, failed. On the other hand 4 was successfully synthesized by intramolecular cyclization of 1‐(2‐mercaptobenzyl)pyrrole‐2‐carboxylic acid 15 by DMAP‐catalyzed DCC method. The pyrrole 6 and 1‐(2‐benzylthiobenzyl)pyrrole‐2‐carboxaldehyde 11 were useful as starting materials to obtain 1‐(2‐benzylthiobenzyl)pyrrole‐2‐carbonitrile 13, which was hydrolyzed to corresponding amide 16. Debenzylation of 16 afforded 1‐(2‐mercaptobenzyl)pyrrole‐2‐carboxyamide 17, whose hydrolysis led to required acid 15.
Diazapolycyclic compounds. XXVI. Reactivity of epoxy‐ and dihydroxy derivatives of diazaquinone adducts
Authors: Alarcón P. , Pardo M. , Soto J. L. 
Published: April 2009

AbstractTreatment of epoxy and dihydroxy derivatives of diazaquinone adducts with concentrated sulfuric acid yields the respective oxo derivatives, while the reaction of the epoxides with boron trifluoride etherate affords trans‐fluorohydrines.
3‐(1‐imidazoyl)‐6‐methoxy‐2‐benzoxazolinone. A byproduct of the synthesis of 6‐MBOA With 1,1′‐carbonyldiimidazole
Authors: Nachman Ronald J. 
Published: April 2009

AbstractPreviously unknown 3‐(1‐imidazolyl)‐6‐methoxy‐2‐benzoxazolinone was isolated as a byproduct of the synthesis of reproductive‐stimulant 6‐methoxybenzoxazolinone (6‐MBOA) with 1,1′‐carbonyldiimidazole. Concomitant with byproduct formation was a 34% reduction in the yield of the desired 6‐MBOA. A brief discussion of the formation of this byproduct and maximization of the yield of 6‐MBOA is included.
Synthesis of 4‐substituted 5,6‐diphenylmorpholine‐2,3‐diones with two or three chiral centers
Authors: Alcaide Benito , López‐Mardomingo Carmen , López‐Sáez Berta , Pérez‐Ossorio Rafael , Plumet Joaquín 
Published: April 2009

AbstractChiral α‐aminoalcohols obtained by stereoselective reduction of α‐iminoketones have been condensed with oxalyl chloride to afford 4‐substituted 5,6‐diphenylmorpholine‐2,3‐diones having two or three chiral centers.
Synthesis of novel imidazo[1,2‐a]pyrrolo[2,1‐c][1,4]benzodiazepines and pyrimido[1,2‐a]pyrrolo[2,1‐c][1,4]benzodiazepines
Authors: Duceppe Jean‐Simon , Gauthier Jean 
Published: April 2009

AbstractSeveral 1 1‐amino‐5H‐pyrrolo[2,1‐c][1,4]benzodiazepines have been used as starting material to prepare a number of derivatives of 9H‐imidazo[1,2‐a]pyrrolo[2,1‐c][1,4]benzodiazepines and 10H‐pyrimido[1,2‐a]pyrrolo[2,1‐c][1,4]benzodiazepines. The imidazole nucleus was built by reaction of amidines with ethyl bromopyruvate or aminoacetaldehyde dimethylacetal. Several derivatives of imidazo[1,2‐a]pyrrolo[2,1‐c][1,4]benzodiazepine have been prepared by formylation of the pyrrole ring followed by formation of thioamides. Condensation of 11‐amino‐5H‐pyrrolo[2,1‐c][1,4]benzodiazepines with diethyl ethoxymethylenemalonate afforded intermediate diesters which were transformed into the corresponding 10H‐pyrimido[1,2‐a]pyrrolo[2,1‐c]‐benzodiazepines.
The reaction of cycloalkanonhydrazones with mercaptoacetic acid. Synthesis of novel N‐aminospirothiazolidinones
Authors: Reddy R. Raji , Iyengar D. S. , Bhalerao U. T. 
Published: April 2009

AbstractCycloalkanone hydrazones undergo condensation with mercaptoacetic acid to give predominantly the spirothiazolidinones. The structures of the products have been established on the basis of physico‐chemical data. These compounds have shown promising antibacterial and antifungal activity.
Reactions of indoles with ortho esters, N,N‐dimethylformamide and N,N‐dimethylacetamide dialkyl acetals
Authors: Bergman Jan 
Published: April 2009

AbstractIndole and N‐methylindole react with oxa stabilized carbocations generated in situ from orthoformates to yield tris(3‐indolyl)methane. The unsymmetrical isomers, e.g. 2‐(N‐methyl‐3‐indolyl)di(N‐methyl‐3‐indolyl)‐methane (4), were not formed as established by an independent synthesis. N,N‐Dimethylacetamide dimethyl‐acetal reacted with 2‐alkyl substituted indoles to produce 1,1‐bis(3‐indolyl)ethanes (3).
On the chichibabin amination of quinoline and some nitroquinolines
Authors: Tondys Hanna , van der Plas Henk C. , Woźniak Marian 
Published: April 2009

AbstractQuinoline is aminated into 2‐aminoquinoline (55‐60%) when treated with potassium amide/liquid ammonia/potassium permanganate at −65°. When the amination is carried out by allowing the solution of quinoline in potassium amide/liquid ammonia to raise from −60° to + 15° before addition of potassium permanganate, the main product is 4‐aminoquinoline. Using as reagent liquid ammonia/potassium permanganate (thus without the presence of potassium amide) 3‐nitroquinoline is exclusively aminated at −40° into 4‐amino‐3‐nitroquinoline. Using the same conditions, from 4‐nitroquinoline 3‐amino‐4‐nitroquinoline is obtained. The mechanism of these amination reactions is discussed.
Cycloadditions of ketenes with cyclic carbodiimides
Authors: Brady William T. , Shieh C. H. 
Published: April 2009

AbstractThe cycloaddition of ketenes with cyclic carbodiimides yields β‐lactams in good to excellent yields. The cycloaddition of equal molar amounts of diphenyl‐, phenylethyl‐ and phenylketenes with cyclic carbodiimides produced a 1:1 cycloaddition product, the expected β‐lactams. However, the cycloaddition of a 2:1 molar ratio of diphenyl‐ and phenylketenes with 1,3‐diazacycloocta‐1,2‐diene respectively, gave the 2:1 cycloadducts, the tricyclodi‐β‐lactams. The cycloaddition of methylchloro‐ and dichloroketenes yielded β‐lactams that were very susceptible to hydrolysis to the N‐substituted cycloureas. A trapping experiment suggests that these reactions proceed through a stabilized dipolar intermediate.
Triazoles. III. The alkylation of 3‐R′‐thio‐5‐amino‐1,2,4‐triazoles
Authors: Reiter J. , Somorai T. , Dvortsák P. , Bujtás Gy. 
Published: April 2009

AbstractThe alkylation of 3‐R′‐thio‐5‐amino‐1H‐1,2,4‐triazoles 1 or their sodium salt with alkyl and aralkyl halides 2, respectively, to yield all the four possible monoalkylated derivatives 3, 4, 5 and 6 was studied. The comparison of the spectral data of different type isomers 3, 4, 5 and 6 isolated and their Schiff bases 8, 9 and 10, respectively, was unequivocal evidence in support of their structure which was then further supported by independent synthesis and ring closure reactions. According to an hplc study the main product of the alkylation is derivative 3, the by‐product is derivative 4, while derivatives 5 and 6 are formed only in insignificant amounts.
Synthesis and reactions of N‐Aryl‐C‐arylsulfonylformohydrazidoyl bromides
Authors: Hassaneen Hamdi M. , Abdelhamid Abdou O. , Fahmi Abdelgawad A. , Shawali Ahmad S. 
Published: April 2009

AbstractBromination of 1‐arylsulfonyl‐1,2‐propanedione‐1‐aryl‐hydrazones 7 in a mixture of acetic acid and acetic anhydride in the presence of sodium acetate gave N‐aryl‐C‐arylsulfonylformohydrazidoyl bromides 5. Treatment of 5 with dibenzoylmethane, acetylacetone, ethyl acetoacetate and ethyl benzoylacetate in ethanol in the presence of sodium ethoxide yielded the pyrazole derivatives 8‐11, respectively. Reaction of 5 with potassium thiocyanate afforded the thiadiazoline derivative 14. The bromides 5 also react with nucleophiles such as morpholine, piperidine, phenoxide, thiophenoxide and benzenesulfinate anions to give the corresponding substitution products 19‐23, respectively. The structures of the products 8‐23 were assigned and confirmed on the basis of their spectral and elemental analyses, their chemical behaviour and alternate synthesis wherever possible.
Imidazolyl derivatives of the chroman ring. 2
Authors: Cozzi Paolo , Pillan Antonio 
Published: April 2009

AbstractThe synthesis of 3‐(1H‐imidazol‐1‐yl)‐4H‐1‐benzopyran‐4‐ones 2 and of 2‐(1H‐imidazol‐1‐yl)‐4H‐1‐benzopyr‐an‐4‐ones 11 are described. The former proceeds through chroman ring closure from 2‐(1H‐imidazol‐1‐yl)‐2′‐hydroxyacetophenones, the latter occurs reacting 3‐bromo‐4H‐1‐benzopyran‐4‐ones with imidazole and represents an example of a new synthesis of 2‐heteroarylchromones. Compounds 2 can be easily reduced to the corresponding chromanones and chromanols previously described in Part 1.
Synthesis of 1,2‐disubstituted isoindoles from o‐phthalaldehyde and primary amines
Authors: Nan'ya Seiko , Tange Toshiaki , Maekawa Eturô 
Published: April 2009

Abstract2‐Alkyl‐1(2‐formylphenyl‐N‐alkyliminomethyl)isoindoles were prepared by the reaction of o‐phthaldehyde with primary amines in 99% ethanol at 0°. 2‐Alkyl‐3‐alkyliminoisoindolinones were isolated from the reaction mixture as by‐products. Their formation mechanism is proposed.
Methylation of 3‐methyl‐ and 3‐phenyl‐4‐arylhydrazonoisoxazol‐5‐ones with methyl iodide and dimethyl sulfate
Authors: Singh Shyam K. , Summers Lindsay A. 
Published: April 2009

AbstractMethylation of 3‐methyl‐4‐arylhydrazonoisoxazol‐5‐ones with methyl iodide affords both 2,3‐dimethyl‐4‐arylazoisoxazol‐5‐ones and 3‐methyl‐4‐(N‐methylarylhydrazono)isoxazol‐5‐ones but with dimethyl sulfate only the former products are formed. 3‐Phenyl‐4‐arylhydrazonoisoxazol‐5‐ones behave in a similar way on methylation with methyl iodide and dimethyl sulfate.
Studies of amine‐induced ring opening of some mesoionic xanthines
Authors: Mbagwu Godwin O. , Bass R. Gerald , Glennon Richard A. 
Published: April 2009

AbstractThe ring‐opening reactions of seven mesoionic thiazolo[3,2‐a]pyrimidine‐5,7‐diones by a series of primary and secondary amines have been investigated. The rates of the ring fission of five N(8)‐substituted mesoionic xanthines with benzylamine were measured and found to follow second order kinetics. The Hammett relationship is followed with ϱ value of + 0.48 in p‐dioxane as solvent. The dependence of rates on temperatures has been studied for the N(8)‐ethyl derivative; the energy of activation (ΔE*) is 25.3 kcals mol−1, the enthalpy of activation (ΔH*) is 24.7 kcals mol−1 and the entropy of activation (ΔS*) is — 4.9 e.u. A slight increase in rate of reaction was observed when the solvent was changed from p‐dioxane to dimethyl sulfoxide. In p‐dioxane at constant mesoionic xanthine concentration, the rate constant for ring opening decreased with increasing benzylamine concentration. These results are consistent with a bimolecular nucleophilic mechanism proceeding by the rate‐determining formation of a charged tetrahedral transition state.
A facile synthesis and structure determination from 13c‐nmr spectroscopy of a novel heterocycle 1,1′‐ethylenebis[2,3,8,8a‐tetrahydro‐5,8a‐dimethyl‐1H‐imidazo[2,1‐c][1,4]thiazine], a case of transannular stabilization
Authors: Tandon Santokh S. , Larkworthy Leslie F. 
Published: April 2009

AbstractThe condensation of 4‐thiaheptane‐2,6‐dione with triethylenetetramine does not produce the macrocycle 1‐thia‐3,14‐dimethyl‐4,7,10‐13‐tetrazacyclopentadeca‐3,13‐diene; instead two molecules of the dione condense with one of the amine to give the title compound.