bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies in the claisen rearrangement. Part XII . Synthesis of benzofuro[3,2‐c] [l]‐6a,lla‐dihydro‐lla‐methylbenzopyrans from 1,4‐diaryloxy‐2‐butynes
Authors: Majumdar K. C. , Thyagarajan B. S. , Balasubramanian K. K. 
Published: March 2009

AbstractSuccessful Claisen rearrangement of a number of 1,4‐diaryloxy‐2‐butynes is reported. The products of such a rearrangement are the benzofuro[3,2‐c]benzopyrans. This novel rearrangement offers a facile synthetic route to tetracyclic derivatives resembling the naturally occurring pterocarpans.
The synthesis of optically active 5‐phenylhydantoins
Authors: Dudley Kenneth H. , Bius Daniel L. 
Published: March 2009

AbstractA number of reagents have been examined for effecting the conversion of an optically pure 2‐phenylhydantoic acid to an optically active 5‐phenylhydantoin. Trifluoroacetic anhydride (TFAA method) and dilute hydrochloric acid (acid‐catalysis method) proved to be the reagents of choice. The dependence of the kinetics of racemization of the 5‐phenylhydantoin system on temperature has been studied in dilute hydrochloric acid solution to support the conclusion that 5‐phenylhydantoins prepared by the acid‐catalysis method are nearly, if not entirely, optically uniform.
Synthetic studies in the lsoxazoko[4,5‐b] pyrazine system
Authors: Abushanab E. , Lee D. Y. , Goodman L. 
Published: March 2009

AbstractThe synthesis of 3‐methylisoxazolo[4,5‐b]pyrazine (5) and its 7‐oxide (6) is reported. Nitration of 6 furnished the 6‐nitro derivative (8) while reaction with phosphoryl chloride provided the chloro derivative (7). Efforts to functionalize the methyl group in 5 were not successful.
Nmr spectral characteristics of N‐H protons in purine derivatives
Authors: Twanmoh Li‐Ming , Wood Harry B. , Driscoll John S. 
Published: March 2009

AbstractProton chemical shifts are examined in a series of twelve purine and three 5‐azapurine derivatives. The assignment of N‐H signals in the xanthine and thioxanthine series, as well as the effects of moisture, concentration and temperature on the N‐H and C‐H nmr spectral characteristics are discussed.
Overcrowded molecules. V. 3,10‐dimethyl‐1,12‐bis(2‐pyridyl)benzo[c] phenanthrene‐2,11‐diol
Authors: Fields D. L. , Regan T. H. 
Published: March 2009

AbstractThe bis ketene acetal adduct of 4a,10a‐diazoniaanthra[1,2‐α]anthracene diperchlorate (10) was used to prepare the highly overcrowded benzo[c]phenanthrene 2 by a known procedure. Its oxidation with cupric chloride provided the isoxazolium zwitterion, 3, via an intramolecular cyclization.
On the reactions of β‐ketoesters with 2,3‐diaminopyridine and its derivatives
Authors: Israel Mervyn , Jones Lynne C. 
Published: March 2009

AbstractStudies in these laboratories and elsewhere on the condensation of β‐ketoesters with unsym‐metrical o‐diamines have thus far failed to explain the factors which govern the direction of cyclization in these reactions. Various additional diamine‐ketoester condensations have been studied and the results compared in an attempt to develop generalizations of predictive value regarding the direction of ring closure to form diazepinones. The following condensation reactions are described: 2,3‐diaminopyridine with 2‐ethoxycarbonylcyclohexanone and with ethyl α‐methylacetoacetate, 5‐bromo‐2,3‐diamino‐4‐methylpyridine with ethyl acetoacetate, 3‐amino‐2‐anilinopyridine and 3‐amino‐2‐methylaminopyridine with ethyl acetoacetate, and N‐methyl‐o‐phenylenediamine with ethyl acetoacetate.
Benzo[b] thiophene derivatives. XIX. The sulfur isosteres of psiloein and related isomers
Authors: Campaigns K. , Rogers R. B. 
Published: March 2009

AbstractThe sulfur analog of psilocin, 3‐(β‐dimethylaminoethyl)‐4‐hydroxybenzo[b ]thiophene, and some O‐methylated and N‐demethylated isomers have been synthesized for pharmacological evaluation. Preliminary tests indicate central nervous system (CNS) activity, but weak pressor activity.
3(2H)isoquinolones. 2. Studies on the structure and formation of aminonaphthols obtained in the preparation of 3(2H)isoquinolones
Authors: Kreighbaum W. E. , Kauanaugh W. F. , Comer W. T. 
Published: March 2009

AbstractThe reaction of a 2‐acylphenylacetic acid derivative (I) with primary amines in glacial acetic acid produces novel, colorless aminonaphthols (III) which are isomeric with the brilliant yellow 3(2H)isoquinolones (II) obtained in the same reaction. A combination of chemical and spectral techniques allowed identification of the isomers as derivatives of 4‐amino‐2‐naphthol. A plausible mechanism of formation of aminonaphthols versus 3(2H)isoquinolones is discussed and supported by chemical synthesis of N‐substituted 2‐aeylphenylacetamides (VIII) and a 1,4‐dihydro‐1‐hydroxy‐3(2H)isoquinolone derivative (IX).
Synthesis and characterization of isomeric cis‐ and trans‐pyrrone model compounds
Authors: Young Philip R. 
Published: March 2009

AbstractIsomeric cis‐ and trans‐imidazopyrrolones, obtained from the reaction of pyromellitic di‐anhydride and o‐phenylenediamine, were prepared as models for pyrrone polymers. The characterization of these model compounds, which represent the repeat unit of the completely cyclized polymer, provided information which could not be obtained by studying the polymer itself. Isomerism was proven by the nuclear magnetic resonance spectra of soluble ester‐benzimidazole derivatives. This study indicated that a single band around 1755 cm−1 should appear in the infrared spectrum of the completely cyclized polymer. The high melting points of the model imidazopyrrolones indicate the extreme thermal stability to be anticipated from perfectly formed pyrrone polymers.
Heterocyclic derivatives of naphthalene‐1,8‐dicarboxylic anhydride. Part I. Nitro‐7H‐benzimidazo[2,1‐a]benz[de]isoquinolin‐7‐ones
Authors: Grayshan P. H. , Peters Arnold T. 
Published: March 2009

AbstractCondensation of o‐phenylenediamine with 2‐, 3‐ and 4‐nitronaphthalene‐1,8‐dicarboxylic anhydrides gives, in each case, an isomer mixture. Separation of the mixtures into the six isomeric mononitro‐7H‐benzimidazo[2,1‐a]benz[de]isoquinolin‐7‐ones is described and the isomers characterised in respect of previously reported data on some isomers; ir and mass spectrum data are reported, the latter showing fragmentation ions which may be used in characterising dyes based on this chromophore. Other new derivatives of 7H‐benzimidazo[2,1‐a]benz[de]isoquinolin‐7‐one are also described.
Synthetic studies leading to DE‐ring analogs of camptothecin
Authors: Hansen John F. , Kamata Kazuyuki , Meyers A. I. 
Published: March 2009

AbstractA synthetic scheme leading to an isomeric DE ring (14) of the anti‐tumor alkaloid, camptothecin, has been achieved. However, the method failed to give the correct pyridone lactone (2) found in this alkaloid.
Synthesis of 1,3,5,7‐tetraazacyclooctane derivatives
Authors: Yoshida H. , Sen G. , Thyagarajan B. S. 
Published: March 2009

AbstractTetraazaadamantane was converted under mild conditions into 1,3,5,7‐tetraazabicyclo[3.3.1]nonane derivatives. The latter were transformed selectively into 1,3,5,7‐tetraazacyclooctane derivatives avoiding the formation of 1,3,5‐triazacyclohexane compounds.
3‐Amino‐5‐phenyl‐1‐(2‐pyridyl)pyrrolidines. Synthesis and stereochemistry
Authors: Hanna Patrick E. 
Published: March 2009

AbstractStereoselective syntheses of trans‐ and cis‐3‐amino‐5‐phenyl‐1‐(2‐pyridyl)pyrrolidine (21 and 24) are reported. Evidence for the relative stereochemistries of 21 and 24 was obtained by preparation of the bicyclic lactams exo‐ and endo‐7‐phenyl‐1,4‐diazabicyclo[3.2.1.]octan‐3‐one (16 and 19) from precursors of 21 and 24.
Intermediaires dans le rearrangement de dimroth d'imidazo[1,2‐a]pyridines
Authors: Jacquier Robert , Lopez Hélène , Maury Georges 
Published: March 2009

AbstractLes imidazo [1,2‐a] pyridines subissent le réarrangement de Dimroth en milieu aqueux basique si le noyau est active par des groupements nitro en position 6 ou 8. La réaction peut ětre limitée à la formation de composés intermédiaires de ce réarrangement qui ont été étudiés en RMN notamment.
Sur une prétendue forme NH stable d'une pyrazoline‐3
Authors: Baumes Raymond , Elguero José , Jacquier Robert , Tarrago Georges 
Published: March 2009

AbstractSelon Wittig et Hutchison (1) la reduction d'un pyrazole N‐substitue par l'hydrure d'aluminum lithium conduit a une pyrazoline‐3 N(H)1 stable.Nous montrons, en fait, que cette reaction s'effectue par reduction d'un isopyrazole en pyrazoline‐2; il est alors necessaire de reconsiderer la transposition des pyrazolènines qui, dans certains cas, conduit aux isopyrazoles et non aux pyrazoles.
The synthesis of some 4H‐pyrimido[2,1‐b]benzothiazol‐4‐ones
Authors: Alaimo Robert J. 
Published: March 2009

AbstractA series of 8‐substituted and 7,8‐disubstituted‐4‐oxo‐3‐(4H‐pyrimido[2,1‐b]benzothiazole)carboxylic acids and esters including a 9‐aza analog were synthesized from substituted 2‐aminobenzothiazoles and diethyl ethoxymethylenemalonate. The 9‐aza analog, ethyl 8‐methoxy‐4‐oxo‐3‐(4H‐pyrido[3′,2′:4,5]thiazolo[3,2‐a]pyrimidine)carboxylate (56), represents the first preparation of this new heterocyclic ring. These compounds were examined for antiparasitic activity, however, no significant activity was detected.
The polar nature of 2,1,3‐benzoxadiazole, ‐benzothiadiazole, ‐benzoselenadiazole and derivatives as determined by their electric dipole moments
Authors: Tobiason F. L. , Huestis Laurence , Chandler Chris , Pedersen Svend E. , Peters Phillip 
Published: March 2009

AbstractPermanent electric dipole moments have been determined in benzene solutions at 25° for the oxygen, sulfur, and selenium series of 2,1,3‐benzodiazoles. The derivatives studied contained 4, 5, and 6 substituted methyl, chloro, nitro, and amino groups. The dipole moment data of the derivatives were analyzed relative to that of the parent species which allowed deductions to be made about the mesomeric structures operating in the compounds. The mesomeric charge transfer increases regularly from the oxygen to the selenium structures, being nearly undetected in 2,1,3‐benzoxadiazole derivatives and very pronounced in the 2,1,3‐benzoselenadiazoles.
A 5‐methylthiopenicillin analog and its transformation to novel bicyclic β‐lactams
Authors: Bose Ajay K. , Fahey John L. , Manhas M. S. 
Published: March 2009

AbstractReaction of methoxyacetyl chloride with 2‐methylthio‐2‐thiazoline resulted in the stereoselective production of one isomer of 6‐methoxy‐5‐methylthiopenam which underwent rearrangement to 6‐methoxy‐7‐methylthio‐5‐oxo‐2,3,4,5‐tetrahydro‐1,4‐thiazepine when treated with trifluoroacetic acid. Subsequent thioamidation and alkylation with methyl iodide provided 5,7‐bismethylthio‐6‐methoxy‐2,3‐dihydro‐1,4‐thiazepine which reacted with methoxyacetyl chloride and triethylamine to give a novel 1,4‐thiazabicyclo[5.2.0]non‐5‐ene. Other substituted bicyclic β‐lactams of similar structure have also been synthesized.
The photo cycloaddition of alkenes to s‐triazolo[4,3‐b] and [2,3‐b]pyridazines
Authors: Bradshaw J. S. , Stanovnik B. , Tišler M. 
Published: March 2009

Abstracts‐Triazolo[4,3‐b]pyridazine (I) reacted with cyclohexene under the influence of ultraviolet light to yield 4a,5,7,8,8a,9‐hexahydro‐9‐methylene‐6H‐s‐triazolo[1,5‐a]indole (IV) and 9‐cyanomethyl‐4a,5,7,8,8a,9‐hexahydro‐6H‐s‐triazolo[1,5‐a]indole (V). These products were formed by the addition of the alkene to the 1,8 positions of I with a concurrent cleavage of the N4N5 bond. Similar additions were observed with cyclopentene and 2,3‐dimethyl‐1,3‐butadiene. The isomeric s‐triazolo[2,3‐b]pyridazine (III) reacted with cyclohexene to form an isomer of IV, 4a,5,7,8,8a,9‐hexahydro‐9‐methylene‐6H‐s‐triazolo[4,3‐a]indole (XV) and two [2 + 2] cycloadducts (XVI and XVII).
The preparation of 5‐(2‐bromoethyl)‐2‐iminooxazolidines via the von braun cyanogen bromide reaction
Authors: Fielden Marvel L. 
Published: March 2009

AbstractThe reaction of certain 1‐alkyl‐3‐pyrrolidinols with cyanogen bromide in ether solution produced 3‐alkyl‐5‐(2‐bromoethyl)‐2‐iminooxazolidines. 5‐(2‐Bromoethyl)‐2‐ethyl‐2‐imino‐5‐phenyloxazolidine was tested for and found devoid of anorectic activity.
Heterocyclic compounds from 3,3‐dimercapto‐1‐aryl‐2‐propen‐1‐ones. Note 1. 4‐Ary1‐1,3‐dihydro‐2H‐1,5‐benzodiazepine‐2‐thiones
Authors: Nardi D. , Tajana A. , Rossi S. 
Published: March 2009

AbstractA series of new 4‐aryl‐1,3‐dihydro‐2H‐1,5‐benzodiazepine‐2‐thiones (3) has been synthesized by condensing the 3,3‐dimercapto‐1‐aryl‐2‐propen‐1‐ones with o‐phenylenediamine. The structure was established by the results of acid cleavage and by nmr spectra. The alkylation of compounds 3 gave 2‐alkylthio‐4‐aryl‐3H‐1,5 benzodiazepines (10).
Heterocyclic studies: New heterocyclic ring systems from isomeric dimethyl diaminophthalates
Authors: Williams R. L. , Shalaby S. W. 
Published: March 2009

AbstractThe synthesis and reactions of dimethyl 3, 4‐ and 4, 5‐diaminophthalate 7 and 9 were investigated. The condensation of these isomeric diaminophthalates and their respective nitroacetamido precursors have been shown to give rise to a variety of five, six and seven membered heterocyclic ring system. Several new tetraazanthracenes have also been prepared in this sequence.
Reactions of 1,2‐Dimethyl‐5‐nitroimidazole, novel methods of conversion of the 2‐Methyl group to a nitrile
Authors: Albright J. Donald , Shepherd Robert G. 
Published: March 2009

Abstract1, 2‐Dimethyl‐5‐nitroimidazole(1)and N,N‐dimethylformamide dicyclohexylacetal gave the 2‐(β‐dimethylaminovinyl) analog 2 and with iodine and pyridine gave the 2‐(1‐pyridinium)methyl compound 3. Benzoyl chloride‐triethylamine and 1 led to benzoylation of the 2‐methyl group to give ketone 9 as the enol benzoate. Nitrous acid or nitrosylsulfuric acid with 9 or its enol ester afforded the oximinoketone 10 which was cleaved with thionyl chloride to give 2‐cyano‐1‐methyl‐5‐nitroimidazole (11) in high overall yield. 1‐Ethyl‐2‐methylbenzimidazole (22) was converted to 2‐cyano‐1‐ethylbenzimidazole (25) similarly. Reaction of 1 with ethyl oxalyl chloride and triethylamine afforded ethyl 1‐methyl‐5‐nitro‐2‐imidazolepyruvate (19) as the enol oxalate. Nitrous acid and 19 gave the oximino pyruvate 20 which effervesced on mild heating to give 2‐cyano‐1‐methyl‐5‐nitroimidazole (11). The preparation of 1‐methyl‐5‐nitro‐2‐imidazoleacetonitrile (39) is reported.
Minor prodiginine pigments from actinomadura madurae and actinomadura pelletieri
Authors: Gerber Nancy N. 
Published: March 2009

AbstractFive minor prodiginine pigments were isolated from Actinomadura madurae and A. pelletieri fermentations. Two of the pigments were shown to be methylcyclooctylprodiginine (7) and ethylcyclononylprodiginine (8). For the others, structures containing oxygen functions in the aliphatic chains (11, 12 and 13) were suggested.
Antituberculous compounds. XXVIII. Synthesis of pyrazolopyridines
Authors: Sekikawa Isao , Nishie Jan , Tono‐Oka Shuichi , Tanaka Yorie , Kakimoto Shichiro 
Published: March 2009

AbstractIn a previous paper it was reported that N′‐alkyl derivative of isonicotinic acid hydrazide (INH) was more active against tuberele bacilli than the acyl derivative containing the same number of carbon atoms. The authors subsequently reported that the pyrido[2, 3‐d]pyridazine was closely related to the acyl derivative of INH except that the terminal carbonyl group was cyclized to the pyridine nucleus, therefore these derivatives were not effective against tubercle bacilli; however, pyridopyridazine, which is similar to the alkyl derivatives of INH, will be more effective against tubercle bacilli. According to the similar expectation, some pyrazolopyridines were prepared.
Interconversion of 3‐Acylaminobenzisoxazoles and 3‐(2‐Hydroxyphenyl)‐1,2,4‐oxadiazoles
Authors: Harsányi Kálmán 
Published: March 2009

AbstractInterconversion of 3‐(2‐hydroxyphenyl)‐1,2,4‐oxadiazoles (1) and 3‐acylaminobenzisoxazoles (2) was observed in the presence of base carboxylate anion, triethylamine, alkali hydroxide, alcoholate. With proton transferring reagents (carboxylate, triethylamine) the equilibrium 1⇌2 is dependent on the substituent R; with anionic reagents (hydroxy anion, ethoxyl anion) the less basic anion of 1 is preferred. Alcohol effects further transformation of this anion and the alcohol adduct anion (6) is subject both to hydrolysis and alcoholysis (7) to yield 3‐amino‐benzisoxazole (3).
Benzo[b]thiophene derivatives. XXI. On the proof of structure of the sulfur isostere of psilocin
Authors: Campaigne E. , Rogers R. B. 
Published: March 2009

AbstractDifferences in the characteristics of several common compounds reported in two independent syntheses of the sulfur analog of psilocin required re‐examination of our products. Additional evidence supporting the structures previously reported by us is presented. This includes proof of 3‐substitution in 4‐methoxy‐3‐β‐dimethylaminoethylbenzo[b]thiophene by deuterium exchange of the 2‐proton, demonstration that the intermediate 4‐methoxy‐N, N‐dimethyl‐3‐benzo[b]thienylglyoxamide is different from the 2‐isomer, and confirmation of the structure of 4‐methoxy‐3‐methylhenzo[b]thiophene, an intermediate in one of the reported syntheses, by three different synthetic methods.
Chemistry of isoindolines. The synthesis of 1,2,3,5,6,7‐Hexahydrobenzo[1,2‐c: 4,5‐c′]dipyrrole and 1,2,3,4,5,6‐Hexahydrobenzo[1,2‐c: 3,4‐c′]dipyrrole
Authors: Slapler John T. , Bornstein Joseph 
Published: March 2009

AbstractThe preparation and properties of 1,2,3,5,6,7‐hexahydrobenzo[1,2‐c: 4,5‐c′]dipyrrole (I) and its isomer, 1,2,3,4,5,6‐hexahydrobenzo[1,2‐c:3,4‐c′]dipyrrole (II), are described. Contrary to the claims of earlier investigators, compound I and its 2,6‐diacetyl and 2,6‐dicarboxarnide derivatives VI and IX are easily preparable, readily isolable, stable substances.
Syntheses and properties of 4,6‐dimelhyl[1,2,5]oxadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)dione 1‐oxide
Authors: Yoneda Fumio , Sakuma Yoshiharu 
Published: March 2009

AbstractNew convenient syntheses of 4,6‐dimethyl[1,2,5]oxadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)‐dione 1‐oxide (I) from 1,3‐dimethyl‐6‐hydroxylaminouracil by means of nitrosative and nitrative cyclizations are described. Compound I was converted into 4,6‐dimethyl[1,2,5]oxadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)dione [4,6‐dimethyl‐5,7(4H,6H)furazano[3,4‐d]pyrimidinedione] by refluxing in dimethylformamide. Transformation of I to 1,3,7,9‐tetramethyl‐2,4,6,8(1H,3H,7H,9H)pyrimido[5,4‐g]pteridinetetrone and/or 1,3,6,8‐tetramethyl‐2,4,7,9(1H,3H,6H,8H)pyrimido[4,5‐g]pteridinetetrone is described.
Studies on the syntheses of analgesics. Part XXXIX . Synthesis of 1,2,3,4,5,6‐ Hexahydro‐8‐hydroxy ‐2,6‐methane‐3,6,1 1‐trimethyl‐2,3‐benzo|g| diazocine and 1,2,3,4,5,10,11,12‐Octahydro‐7‐hydroxy‐1,5‐dimethylpyridazino|2,3‐b| isoquinoline |studies on the syntheses of heterocyclic compounds. Part LXI |
Authors: Kametani Tetsuji , Kigasawa Kazuo , Hiiragi Mincharu , Wakisaka Kikuo , Wagatsuma Nagatoshi , Kusama Osamu , Urya Tsunco 
Published: March 2009

Abstract1,2,3,4,5,6‐Hexahydro‐8‐hydroxy‐2,6‐methano‐3,6,1 1‐trimethyl‐2,3‐benzo |g| diazocine (IV) and 1,2,3,4,5,10,11,12‐octahydro‐7‐hydroxy‐1,5‐dimethylpyridazino |2,3‐b| isoquinoline (VI) were synthesized from a common intermediate, 3‐(3‐methoxyphenyl)‐2‐butanone (VII), through several steps. Reaction of VII with ethyl bromoacetate gave the mixture of ethyl 4‐keto‐3‐(3‐methoxyphenyl)‐3‐methylpentanoate (XIV) and ethyl 4‐keto‐5‐(3‐methoxyphenyl)hexanoate (XV) which were hydrolyzed and condensed with methylhydrazine to give the 4,5‐dihydro‐5‐(3‐methoxyphenyl)‐2,5,6‐trimethyl‐ (XVIII) and 4,5‐dihydro‐6‐(3‐methoxy‐α‐methylbenzyl)‐2‐methylpyridazine‐3(2H)one (XIX). Reduction of XVIII and XIX followed hy cyclization afforded the 2,3‐benzo |g| diazocine (XXII) and the pyridazino |2,3‐b| isoquinoline (XXIII) which on treatment with 47% hydrobromine acid afforded the phenolic bases (IV and VI), respectively. The mass spectrum of IV, VI, XXII and XXIII was also discussed.
Synthèse de l'oxo‐7 7H cyclohepta[b] pyridine et de quelques dérivés
Authors: Letouzé MM. D. , Duflos J. , Queguiner G. , Pastour P. 
Published: March 2009

AbstractThis communication describes the synthesis of 7‐one (7H) cyclohepta[b]pyridine and some derivatives (6,8‐dimethyl; 8‐methyl; 8‐ethyl….). These compounds have been obtained by condensation of ketones with 2,3‐diformylpyridine.
Synthèse du mèthyl‐1 diformyl‐2,3 pyrrole, de la méthyl‐1 pyrrolo[2,3‐d] pyridazine et de la méthyl‐1 oxo‐6 (6h)cycloheptatrieno[b] pyrrole
Authors: Duflos MM. J. , Letouzé D. , Queguiner G. , Pastour P. 
Published: March 2009

AbstractThis communication describes the synthesis of l‐methyl‐2,3‐diformylpyrrole. This new compound is used to prepare a new heterocycle, l‐methylcyclohepta[b]pyrrol‐6‐one and thus allows a new synthesis of l‐methylpyrrolo[2,3‐d]pyridazine.
Thermal reaction of ethynylphthalimides and hydration of N‐(4‐ethynylphenyl)phthalimide
Authors: Hergenrother P. M. 
Published: March 2009

AbstractThree ethynyl substituted phenylphthalimides were prepared and characterized by high pressure liquid chromatography, differential scanning calorimetry, and mass spectroscopy. When the preparation of N‐(4‐ethynylphenyl)phthalimide was attempted by the thermal cyclodehydration of N‐(4‐ethynylphenyl)‐2‐carboxybenzamide, N‐(4‐acetylphenyl)phthalimide was obtained as the major component. This unusual hydration of an ethynyl group was investigated and a mechanism was proposed to explain it.
The preparation of 2,6‐diaminopyrazine, 2,6‐diazidopyrazine and some of their derivatives
Authors: Shaw John T. , Brotherton Christine E. , Moon Robert W. , Winland Mark D. , Anderson Mark D. , Kyler Keith S. 
Published: March 2009

AbstractA much improved synthesis of the heretofore difficultly obtainable 2,6‐diaminopyrazine (4) was afforded by the low‐pressure catalytic hydrogenation (palladium on carbon) of 2,6‐diazido‐pyrazine (2); reaction of 2,6‐dichloropyrazine (1) and sodium azide gave 2 in 84% yield. The outcome of the reduction was found to be solvent dependent: 1,2‐dimethoxyethane containing aqueous ammonia gave 4 in 83% yield; 1,2‐dimethoxyethane alone gave 5‐aminotetrazolo[1,5‐a]‐pyrazine (3) in 26% yield. Additional alternative syntheses of 3 and 4 are described. A number of acyl and azo derivatives of 4 were prepared. Reactions of 2 with dimethyl acetylenedicarboxylate and ethyl acetate (base catalyzed) leading to vic‐triazole derivatives are also described.
The addition of hydroxylamine to the halogenated uracils
Authors: Priest John H. , Scheffler Julie E. , Sander Eugene G. 
Published: March 2009

AbstractHydroxylamine adds reversibly to C‐6 of uracil bases via a multistep mechanism. Equilibrium constants measured at several pH values, 25°, μ = 3.0 M are: uracil, 0.25 M−1; 5‐iodouracil, 0.30 M−1, 5‐bromouracil, 0.24 M−1, 5‐chlorouracil, 0.06 M−1 and 5‐fluorouracil, 5.11 M−1. The kinetics of hydroxylamine addition to both 5‐bromo‐and 5‐iodouracil are complex. At low hydroxylamine buffer concentrations, the rate constants are second‐order with respect to hydroxylamine buffer but at higher concentration a first‐order dependence is approached. Hydroxylamine elimination from 5‐iodo‐6‐hydroxylamino‐5,6‐dihydrouracil is subject to general base catalysis by tris(hydroxy‐methyl)aminomethane but at higher concentrations the rate constants are not proportional to the concentration of general base. This reaction is subject to solvent effects where increasing ethanol concentration depresses the rate when measured at constant pH. These kinetics can be rationalized in terms of a multistep reaction pathway in which hydroxylamine addition to C‐6 of the halogenated uracil precedes general acid catalyzed proton transfer to C‐5 yielding the final 6‐hydroxylaminodihydropyrimidine product.