bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of new fluorescent dyes in the benzoxazinone series: Aminobenzoxazinones with a rigidized structure
Authors: Le Bris Marie‐Thérèse 
Published: March 2009

AbstractThe structure of 7‐aminobenzoxazinones was modified by enclosing their amino nitrogen atom in a julolidyl ring. This rigidization was expected to enhance the fluorescence performances in this series. Several fluorescent dyes and styryl derivatives were prepared and their spectral characteristics were investigated. Comparison with homologous benzoxazinones with a flexible amino group shows that rigidization does not improve the quantum yield and the photochemical stability, in contrast with the results reported for other classes of dyes, like coumarins or rhodamines.
Synthesis and spectral data of pyrido[2,3‐e]‐as‐triazines
Authors: Pié N. , Quéguiner G. 
Published: March 2009

AbstractThe pyrido[2,3‐e]‐as‐triazine and its 3‐phenyl derivatives were prepared via cyclisation with polyphosphoric acid of suitable 3‐substituted 2‐aminopyridines obtained by reduction of the corresponding 2‐nitropyridines. The 3‐substituted 2‐nitropyridines were obtained by action of hydrazine or benzoylhydrazide with the appropriate 3‐halo‐2‐nitropyridines; only 3‐fluoro‐2‐nitropyridine leads to the 3‐substituted 2‐nitropyridines. This experimental results are in agreements with the CNDO and MNDO calculations.
Bruceines D, E and H
Authors: Li Xian , Wu Lijun , Konda Yaeko , Iguchi Mieko , Takahasi Hiroshi , Harigaya Yoshihiro , Onda Masayuki 
Published: March 2009

AbstractThe absolute stereochemistry of bruceines D, E and H has been confirmed to be 1S, 5S, 7R, 8R, 9R, 10S, 11R, 12S, 13R, 14R, 15R and additionally 2S for bruceine E by a combination of 2D nmr [1H‐1H and 1H‐13C (one‐bond and long‐range) COSY] nOe and cd spectroscopic analyses.
Potential antitumor agents. III. Synthesis of pyrazolo[3,4‐e]pyrrolo[3,4‐g]indolizine and 1H‐pyrazolo[3,4‐e]indolizine derivatives
Authors: Artico Marino , Massa Silvio , Stefancich Giorgio , Silvestri Romano , Di Santo Roberto , Corelli Federico 
Published: March 2009

AbstractThe preparation of 5‐dimethylaminoethyl‐4,6‐dioxo‐1‐phenyl‐1,4,5,6‐tetrahydropyrazolo[3,4‐e]pyrrolo‐[3,4‐g]indolizine, a derivative of the still unknown tetracyclic parent ring pyrazolo[3,4‐e]pyrrolo[3,4‐g]indolizine, is reported starting from 1‐phenyl‐5‐(1‐pyrryl)pyrazole‐4‐acetonitrile by PPA catalyzed double cyclization of the related oxalylcyanomethyl derivative and subsequent alkylation. The synthesis of 4,5‐bis(isopro‐pylaminocarbonyloxymethyl) and 4,5‐bis‐(cyclohexylaminocarbonyloxymethyl) derivatives of 1‐phenyl‐1H‐pyrazolo[3,4‐e]indolizine is also described. The new tricyclic and tetracyclic derivatives were tested as potential antitumor agents.
6‐aza‐5,8,10‐trideaza analogues of tetrahydrofolic acid and tetrahydroaminopterin: Synthesis and biological studies
Authors: Rosowsky Andre , Bader Henry , Moran Richard G. , Freisheim James H. 
Published: March 2009

Abstract6‐Aza‐5,8,10‐trideaza‐5,6,7,8‐tetrahydrofolic acid (3) and 6‐aza‐5,8,10‐trideaza‐5,6,7,8‐tetrahydroamino‐pterin (4) were synthesized from 6‐aza‐5,8,10‐trideaza‐5,6,7,8‐tetrahydropteroic acid (5) and 4‐amino‐6‐aza‐5,8,10‐trideaza‐4‐deoxy‐5,6,7,8‐tetrahydropteroic acid (6), respectively, by mixed carboxylic‐carbonic anhydride condensation with dimethyl L‐glutamate followed by ester hydrolysis. The pteroic acid analogues5and6were prepared in several steps from 1‐benzyl‐3‐carbethoxypiperidin‐4‐onevia2‐amino‐6‐benzyl‐5,6,7,8‐te‐trahydropyrido[4,3‐d]pyrimidin‐4(3H)‐one (7). Compound3did not inhibit the growth of L1210 mouse leukemia cells in culture, and was not an inhibitor of dihydrofolate reductase (DHFR) or thymidylate synthase (TS). It was a very poor substrate for mouse liver folylpolyglutamate synthetase (FPGS). The 2,4‐diamino analogue4was only a marginal substrate for FPGS, yet showed activity comparable to methotrexate as a DHFR inhibitor and as an inhibitor of tumor cell growth. The cytotoxicity of4is noteworthy because this compound is, to our knowledge, the first example of a classical antifolate which forms polyglutamates poorly even though it contains an intactp‐aminobenzoyl‐L‐glutamic acid side‐chain. The inability of3and4to form polyglutamates indicates that a basic nitrogen at position 6 is highly unfavorable for binding to FPGS.
Imidazo[2,1‐b]thiazole carbamates and acylureas as potential insect control agents
Authors: Andreani Aldo , Rambaldi Mirella , Carloni Patricia , Greci Lucedio , Stipa Pierluigi 
Published: March 2009

AbstractImidazo[2,1‐b]thiazole carbamates and acylureas were prepared by reaction of 5‐hydroxymethylimidazo‐[2,1‐b]thiazole and imidazo[2,1‐b]thiazole‐5‐carboxyamide with arylisocyanates. The products formed depend from the substituent bonded at the 6 position of the imidazothiazole moiety, and from the reaction conditions.
An improved synthesis of indazole‐3‐carboxylic acid
Authors: Ferrari Marinella , Ripa Alberto , Ripa Giorgio , Sisti Massimo 
Published: March 2009

AbstractA new and efficient synthesis of indazole‐3‐carboxylic acid is reported. The method consists in reacting β‐acetylphenylhydrazine with chloral hydrate and hydroxylamine hydrochloride in acidic medium to afford N‐acetylaminoisonitrosoacetanilide which, in turn, is converted into the title compound by treatment with sulphuric acid.
Sodium periodate oxidation of tetrahydro‐β‐carboline derivatives
Authors: Gatta Franco , Misiti Domenico 
Published: March 2009

AbstractThe oxidation of some 3‐(methoxy‐ and ethoxycarbonyl)tetrahydro‐β‐carboline derivatives with sodium periodate led to the formation of 1, 4‐benzodiazonine derivatives or fully aromatic β‐carbolines depending on both nature and number of substituents at 1‐position.
Reaction of 1‐(3, 4‐dimethoxybenzylidene)‐6, 7‐dimethoxyisochroman‐3‐one with lithium aluminium hydride: Formation of 1‐(3, 4‐dimethoxybenzylidene)‐6, 7‐dimethoxyisochroman
Authors: Domínguez E. , Iriondo C. , Laborra C. , López P. , Martínez J. , Zamora F. 
Published: March 2009

AbstractEvidence is presented to indicate that the reductive reaction of the isochromanone derivative 1 by means of lithium aluminium hydride (LAH), yielded the isochroman 2 together with small amounts of naphthalene derivatives. All new compounds have been identified from spectroscopic and analytical data.
Syntheis of 2‐aryloxy‐ and 2‐arylalkoxy‐1‐(2‐piperidyl)ethanols
Authors: Mauleón David , Pujol M. Dolors , Minguillón Cristina , Miquel Jaume 
Published: March 2009

AbstractThe preparation and separation of diastereomeric pairs of a series of 2‐aryloxy‐ and 2‐arylalkoxy‐1‐(2‐piperidyl)ethanols is reported. The erythro aminoalcohols were converted into threo isomers by thionyl chloride treatment of their N‐acetyl derivatives and alkaline hydrolysis.
Ring‐degenerate rearrangement of 5‐amino‐4‐iminomethyl‐1, 2, 3‐triazoles
Authors: L'Abbé Gerrit , Vandendriessche Anna 
Published: March 2009

Abstract5‐Amino‐4‐(substituted)iminomethyl‐1‐phenyl‐1, 2, 3‐triazoles 5 rearrange thermally to 4‐amidino‐substituted triazoles 6 instead of undergoing the Dimroth rearrangement to 5‐anilinotriazoles 3.
Diels‐alder reactions of 3, 6‐diphenyl‐1, 2, 4, 5‐tetrazine and 3, 6‐di(2‐pyridyl)‐1, 2, 4, 5‐tetrazine with some 1‐morpholinocycloalkenes
Authors: Atfah M. Adnan 
Published: March 2009

AbstractThe reactions of 3, 6‐diphenyl‐1, 2, 4, 5‐tetrazine 1 and 3, 6‐di(2‐pyridyl)‐1, 2, 4, 5‐tetrazine 2 with the enamines 3a‐d derived from morpholine and the 5‐,6‐,7‐ and 8‐membered cyclic ketones have been investigated. A number of pyridazine derivatives 4–7 most of which are new have been reported. Moreover, a novel procedure for the aromatization of pyridazines 5a‐d to the corresponding pyridazine 7b‐d via oxidative elimination using hydrogen peroxide is described. The structures of products 4–7 were confirmed by spectral methods and elemental analysis.
Studies on pyrazines. 18. A new and convenient synthesis of 2‐amino‐3‐cyanopyrazine
Authors: Sato Nobuhiro 
Published: March 2009

AbstractThe titled compound, 2‐amino‐3‐cyanopyrazine (1), was prepared by reaction of 3‐aminopyrazine 1‐oxide (7) with trimethylsilyl cyanide. Furthermore, conditions of individual steps in synthetic route to 7 starting from 2‐pyrazinecarboxamide were optimized.
Preparation, lithiation and transformation of N‐(benzotriazol‐1‐ylmethyl) heterocycles
Authors: Katritzky Alan R. , Drewniak‐Deyrup Malgorzata , Lan Xiangfu , Brunner Frederic 
Published: March 2009

AbstractIndole, carbazole, pyrrole, imidazole, benzimidazole, 2‐methyl‐ and 2‐phenylbenzimidazole, and 1, 2, 4‐triazole have each been converted into their N‐(benzotriazol‐1‐ylmethyl) derivatives. The pyrrole, indole, and carbazole adducts undergo smooth lithiation at the inter‐ring methylene group and subsequent reaction there with electrophiles. For the imidazole, benzimidazole, and triazole systems, lithiations at other molecular positions competed.
Synthesis and13C‐NMR study of novel pyrazolo[5′,1′:3, 4][1, 2, 4]triazino[5, 6‐d]pyrimidines
Authors: Kurasawa Yoshihisa , Kamigaki Yumiko , Kim Ho Sik , Futatsukawa Rika , Kanoh Megumi , Okiyama Mari , Takada Atsushi , Okamoto Yoshihisa 
Published: March 2009

AbstractThe pyrazolo[5′, 1′:3, 4][1, 2, 4]triazino[5, 6‐d]pyrimidines5a‐c, 6were synthesized from the pyrazolo[5, 1‐c]‐[1, 2, 4]triazines1a, cand the ring carbon signals of5a‐c, 6were assigned by the aid of coupling constant [J(13C‐1H)] data.
ortho effect on the nitrosation of the 2,3‐diphenyl‐5(2‐methoxyphenyl)pyrrole
Authors: Ceraulo Leopoldo , Agozzino Pasquale , Ferrugia Mirella , Sprio Vincenzo 
Published: March 2009

AbstractA comparison of the behaviour on the nitrosation of the isomers 5‐(2‐methoxyphenyl)‐ (1a) 5‐(3‐methoxyphenyl)‐ (1b) and 5‐(4‐methoxyphenyl)2,3‐diphenylpyrroles (1c) carried out in the usual way with iso‐amyl nitrite in a solution of sodium ethoxide in ethanol evidences that 1a is dramatically less reactive with respect to 1b and 1c. The different reactivity was ascribed to the occurrence of a strong hydrogen bond involving pyrrole NH and the ortho‐methoxy group.
Mass spectral study of differently substituted 2‐oxo‐ and 2‐thioxo‐1,3,4‐benzotriazepines
Authors: Vainiotalo P. , Mälkönen P. J. , Richter P. , Morgenstern O. 
Published: March 2009

AbstractThe mass spectra of seven 2‐thioxo‐ and four 2‐oxo‐1,3,4‐benzotriazepines were recorded under electron ionization, and the fragmentation patterns were elucidated by exact mass measurement and metastable ion analysis. Some variations in the nature and position of the substituents greatly affected the mass spectra, allowing easy differentiation of isomeric compounds. The most characteristic feature of the mass spectral behavior of the compounds was the large number of ring contraction and complicated rearrangement reactions.
2‐(o‐Hydroxyanilido)alkylnitriles vs. 2‐[1‐(o‐hydroxyanilido)alkyl]‐benzoxazoles as products from o‐aminophenol and cyanohydrins
Authors: Huang Jamin , Haigh Dianne S. 
Published: March 2009

AbstractThe reaction of o‐aminophenol with cyanohydrins leads to the formation of novel benzoxazoles 2 or the expected 2‐(o‐hydroxyanilido)alkylnitriles 3 or mixtures of these two, depending on the alkyl substituents on the cyanohydrin. The formation of benzoxazoles 2 was found to be due to the intrinsic instability of the corresponding 2‐(o‐hydroxyanilido)alkylnitriles, such as 4.
Chemistry of 5(2H)‐isoxazolones: Novel conversion of positional isomers
Authors: Batra Sanjay , Akhtar Mohammad Shamim , Seth Manju , Bhaduri Amiya Prasad 
Published: March 2009

AbstractReactions of 4‐arylidene‐3‐methyl‐5(4H)‐isoxazolones with nucleophiles lead to 4‐substituted‐benzyl‐3‐methyl‐5(2H)‐isoxazolones. Formation of 5(4H)‐ and 5(2H)‐isoxazolone derivatives have been observed when 4‐substituted‐arylidene‐3‐rriethyl‐5(4H)‐isoxazolones are reacted with methyl magnesium iodide. Oxidation of 4‐substituted‐benzyl‐3‐methyl‐5(2H)‐isoxazolones with manganic acetate and pyridinium chlorochromate, gives 4,4′‐bis[4‐substituted‐benzyl‐3‐methyl‐5(4H)‐isoxazolone]. Oxidation of 4‐substituted‐benzyl‐3‐methyl‐5(2H)‐isoxazolones with metachloroperbenzoic acid gives 4‐hydroxy‐4‐substituted‐benzyl‐3‐methyl‐5(4H)‐isoxazolones and reactions of the same substrates with N‐bromosuccinimide furnish 4‐bromo‐4‐substitutedbenzyl‐3‐methyl‐5(4H)isoxazolones.
Opioid conformations: The remarkable effect of C‐14 substituents on ring c conformations of 6α and 6β epimers of 6‐substituted epoxymorphinan opioid ligands
Authors: Crouch Ronald C. , Bhatia Ashok V. , Lever O. William 
Published: March 2009

AbstractHigh field1H nmr studies have shown that the nature of theC‐14 substituents has a remarkable influence on ringCconformation of epoxymorphinan opioids which have a 6α‐hydroxyl group. In sharp contrast to the ringCtwist‐boat conformation observed in those 6α‐hydroxy compounds which also have a 14‐hydroxyl group (α‐naltrexol; α‐oxymorphol), ringCexists predominantly as a chair conformer in 6α‐hydroxy compounds which have a proton bound toC‐14 (dihydromorphine; dihydrocodeine). The 6β‐hydroxy compounds (β‐naltrexol; β‐oxymorphol) have a ringCchair conformation in agreement with earlier studies.
Reaction of N‐[(α‐acetoxy)‐4‐pyridylmethyl]‐3,5‐dimethylbenzamide with alkyl isocyanates
Authors: Braña Miguel F. , Castellano José M. , Donoso Rosa , López Rodríguez María L. , Yunta María J. R. , Walker Nigel P. C. 
Published: March 2009

AbstractReaction of N‐(α‐acetoxy)4‐pyridylmethyl]‐3,5‐dimethylbenzamide 3 with methyl and ethyl isocyanates afforded 1,3‐dimethyl and 1,3‐diethyl‐4‐(3,5‐dimethylbenzoylamino)‐2‐oxoimidazolidine‐5‐spiro‐4′‐[1′,4′‐dihydro‐1′‐acetyl]pyridine 6a,b, respectively. However, the reaction of 3 with isopropyl, t‐butyl and phenyl isocyanates gave the corresponding N,N′‐diurea and the dimerization compound 8. The structure of 6a was confirmed by crystal X‐ray diffraction analysis.
A novel synthetic route to 1,2‐dimethyl‐5‐phenyl‐1H‐imidazo[4,5‐b]pyridin‐7‐ol
Authors: Lis Randall , Traina Joseph A. , Huffman John C. 
Published: March 2009

AbstractHeating a mixture of 4‐amino‐1,2‐dimethyl‐1H‐imidazole‐5‐carboxylic acid ethyl ester with ethyl benzoyl acetate resulted in the formation of 8‐ethoxycarbonyl‐6,7‐dimethyl‐4‐oxo‐2‐phenylimidazo[1,5‐a]pyrimidin‐5‐ium, hydroxide, inner salt. This compound was then transformed into 1,2‐dimethyl‐5‐phenyl‐1H‐imidazo‐[4,5‐b]pyridin‐7‐ol via several intermediates. A number of structurally interesting compounds were also isolated during the course of this work. Thus, the target ring system was formed by a circuitous series of ring‐chain tautomerizations/rearrangements.
Réductions chimique et électrochimique de 5H‐benzopyranno[4,3‐d]pyrimidines
Authors: Bellec Christian , Bellassoued‐Fargeau Marie‐Claude , Graffe Bernadette , Sacquet Marie‐Claude , Maitte Pierre 
Published: March 2009

AbstractThe chemical reduction of 5H‐[1]benzopyranno[4,3‐d]pyrimidines with lithium aluminum hydrrde leads to 3,4‐dihydro derivations. The electro‐chemical reducation in acidic medium shows two monoelectronic cathodic waves. In netural or basic medium, substituted compounds in 2 position show a single bielectronic wave while two bielectronic waves are observed for unsubstituted compounds In all cases, preparative electrolysis lead to a hydrodimer in the 4,4′‐positiom.
A novel preparation of thiazolo[5,4‐c]pyridines and the synthesis of some imidazo[4,5‐c]pyridines and oxazolo[4,5‐c]pyridines
Authors: Katner Allen S. , Brown Raymond F. 
Published: March 2009

AbstractDiethoxymethyl acetate was used to cyclize o‐disubstituted aminopyridines to oxazolo[4,5‐c]pyridines and imidazo[4,5‐c]pyridines. All the possible imidazole‐methylated imidazo[4,5‐c]pyridines were prepared. A novel synthesis of 2‐substituted thiazolo[5,4‐c]pyridines and 4‐amino‐3‐pyridinethiol was discovered.
Synthesis of thiocarbonyl and heterocyclic compounds from 2‐methylene‐1,3‐dithietanes
Authors: Okajima Nobuyuki , Okada Yoshiyuki 
Published: March 2009

Abstract2‐Methyl‐1,3‐dithietanes bearing electron withdrawing groups on the methylene carbon atom were synthesized and their reactivities were studied. These compounds readily underwent a ring‐opening reaction with a variety of nucleophic reagents such as amines, alcoholate and thiolate anions to yield thioamides, thionoesters and dithioesters, respectively. The products were applied for synthesis of heterocycles such as thiadiazoles, isothiazolones and pyrazoles.
Picryl derivatives of 5‐nitro‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one
Authors: Coburn Michael D. , Lee Kien‐Yin 
Published: March 2009

AbstractTreatment of 5‐nitro‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (1) with picryl fluoride (PkF) in 1‐methyl‐2‐pyrrolidinone (NMP) gave a mixture of a monopicryl and a dipicryl derivative of 1 in a ratio of 2:1, respectively, regardless of the initial concentrations of 1 and PkF. The products were identified as 5‐nitro‐2‐picryl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (2) by X‐ray crystallography and 5‐nitro‐2,4‐dipicryl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (4) by 15N labeling experiments.
A new alkaline rearrangement of the benzofuran skeleton. One step transformation of 2‐(2‐benzofuranyl)benzonitriles into (Z)‐phenylmethyleneisoindolinones
Authors: Guillaumel J. , Boccara N. , Demerseman P. , Royer R. , Bideau J. P. , Cotrait M. , Platzer N. 
Published: March 2009

AbstractThe alkaline hydrolysis of 2‐(2‐benzofuranyl)benzonitriles 2 by potassium hydroxide under reflux in ethanol stops at the corresponding amides 5. Using other solvents (ethylene glycol or methoxyethanol) at higher temperatures, one can obtain either the amides 5, the acids 1 or rearrangement products depending on the experimental conditions. The rearrangement products were identified as (Z)phenylmethylenedihydroisoindolinones 6 resulting from opening of the furan ring. The structures of the compounds 6 were established by 1H nmr spectroscopy (nOe) and X‐ray crystallography.
Curtius rearrangement in the 5‐phenyl‐1,4‐benzodiazepine series. Unprecedented participation by an imine nitrogen
Authors: Bock Mark G. , Dipardo Robert M. , Carson Kenneth G. , Freidinger Roger M. 
Published: March 2009

AbstractThe previously unknown 3‐aminomethyl‐1,3‐dihydro‐5‐(2′‐fluorophenyl)‐2H,4‐benzodiazepin‐2‐one, 3a, was synthesized in two steps as a racemate. In the chiral series, 3(S)‐azidocarbonylmethyl‐1,3‐dihydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐one, 12b, was prepared from Nα‐Cbz‐β‐methylaspartate in five synthetic operations and subjected to Curtius rearrangement. The intermediate isocyanate was trapped intramolecularly by the 5‐imine nitrogen of the benzodiazepine ring in 12b. This unanticipated result runs counter to the generally held dictum that the isocyanate group has a strictly linear shape.
The synthesis and transformations of 3‐ethoxycarbonyl‐2‐isothiocyanatopyridine. Pyrido[2,3‐d]pyrimidines and some azolopyrido[2,3‐d]pyrimidines
Authors: Urleb Uroš , Stanovnik Branko , Tišler Miha 
Published: March 2009

Abstract3‐Ethoxycarbonyl‐2‐isothiocyanatopyridine (2), prepared from 2‐amino‐3‐ethoxycarbonylpyridine (1) by the thiophosgene method, was converted into thiouretanes 3 and 4, 1,4‐disubstituted thiosemicarbazide 6, thioamide 8, and thioureas 15 and 18. The compounds 2 and 3 were converted into bicyclic pyrido[2,3‐d]pyrimidines 5, 9, 10, 11, 12, 16, and 17, and tricyclic azolopyrido[2,3‐d]pyrimidines 13 and 14.
Pyrolysis of azidopyrazines
Authors: Watanabe Tokuhiro , Ueda Ikuko , Hayakawa Naomi , Kondo Yasuo , Adachi Hiroko , Iwasaki Akiko , Kawamata Shizuko , Mentori Fumiko , Ichikawa Miyuki , Yuasa Kayo , Ohta Akihiro , Kurihara Teruo , Miyamae Hiroshi 
Published: March 2009

Abstract2,3‐Dichloro‐ and 2,5‐dichloropyrazines were treated with sodium azide. The former gave diazidopyrazines and the latter, monoazidomonochloropyrazines. Pyrolysis of 2,3‐diazidopyrazines resulted the production of 1,2‐dicyanoiminoethanes and that of 2‐azido‐5‐chloropyrazines, chloroimidazoles.
The reaction of 1‐(N‐phenacylidene)amino‐1,2,3‐triazoles with diphenylnitrilimine
Authors: Bojilova A. , Rodios N. A. , Tsoleridis C. A. , Alexandrou N. E. 
Published: March 2009

AbstractDiphenylnitrilimine reacts with 1‐(N‐phenacylidene)amino‐1,2,3‐triazoles 1 to give mainly 1,2,4‐ and 2H‐1,2,3‐triazoles 2 and 3. CNDO/2 calculations were made on the compounds 1 and the cycloaddition was also examined on the basis of the interacting frontier molecular orbitals.
Synthesis of certain 6‐alkylthio‐2,2′‐anhydro‐5‐azauridines
Authors: Purkayastha Subhasish , Panzica Raymond P. 
Published: March 2009

Abstractβ‐D‐Arabinofurano[1′,2′:4,5]oxazolo‐s‐triazin‐4‐one‐6‐thione (7b) and its t‐butyldimethylsilyl protected counterpart 7a were synthesized by treating the appropriate 2‐amino‐β‐D‐arabinofurano[1′,2′:4,5]‐2‐oxazoline with ethoxycarbonyl isothiocyanate. These 2,2′‐anhydro‐s‐triazine nucleosides were then subjected to alkylation under similar reaction conditions. Alkylation of 3′,5′‐bis(O‐t‐butyldimethylsilyl)‐β‐D‐arabinofurano[1′,2′:‐4,5]oxazolo‐s‐triazin‐4‐one‐6‐thione (7a) provided the targeted S‐alkylated nucleosides, i.e., the C6‐SCH3 (9a), C6‐SCH2‐CH = CH2 (10a), and C6‐S‐CH2‐C = CH (11a), in reasonable yields. Attempted deprotection of these nucleosides failed. In order to circumvent this problem, 7b was alkylated with the same reagents. In each case, instead of the expected S‐alkylated anhydronucleosides, a mixture of the 5‐N‐alkylanhydro‐s‐triazine‐4,6‐dione and 5‐N‐alkylanhydro‐s‐triazin‐4‐one‐6‐thione derivatives were obtained. The 2,2′‐anhydro linkage of 7a was also found to be more stable than the s‐triazine ring to mild base. Basic conditions displaced the C6‐sulfur substituent and eventually caused ring opening of the s‐triazine aglycone.
Synthesis of fluoromethyl, difluoromethyl and trifluoromethyl analogues of pyrazosulfuron‐ethyl as herbicides
Authors: Morimoto Katsushi , Makino Kenzi , Yamamoto Susumu , Sakata Gozyo 
Published: March 2009

AbstractEthyl 1‐fluoromethyl‐5‐(4,6‐dimethoxypyrimidin‐2‐ylcarbamoylsulfamoyl)pyrazole‐4‐carboxylate 1b, a new fluoromethyl analogue of the herbicide pyrazosulfuron‐ethyl la, was prepared from ethyl 1‐fluoromethylpyrazole‐4‐carboxylate 4b. The difluoromethyl and trifluoromethyl analogues 1c,d were also synthesized from ethyl pyrazole‐4‐carboxylate 2 via difluorocarbene reaction.
A facile synthesis of novel 1,2‐diazepino[3,4‐b]quinoxalines by a 1,3‐dipolar cycloaddition reaction
Authors: Kim Ho Sik , Kurasawa Yoshihisa , Yoshii Chiemi , Masuyama Minako , Takada Atsushi , Okamoto Yoshihisa 
Published: March 2009

AbstractThe 1,3‐dipolar cycloaddition reaction of the quinoxaline 4‐oxides 4a,b with 2‐chloroacrylonitrile gave the 2,3‐dihydro‐1H‐1,2‐diazepino[3,4‐b]quinoxalines 5a,b, respectively, which were converted into the 2,3,4,6‐tetrahydro‐1H‐1,2‐diazepino[3,4‐b]quinoxalines 7a,b and 8a,b, respectively.
The synthesis of 6‐C‐substituted 9‐methoxymethylpurine derivatives
Authors: Hamamichi Norimitsu , Miyasaka Tadashi 
Published: March 2009

Abstract6‐Cyanomethylene (2), which was prepared via 1 by substitution with malononitrile, has been catalytically hydrogenated to the α‐(aminomethylene)‐9‐(methoxymethyl)‐9H‐purine‐6‐acetonitrile (3) in good yield using N,N‐dimethylformamide‐benzene as solvent over Pd‐C under medium pressure. Intermediate 3 was derived to aldehyde 5 by hydrolysis with acid or base. Substitution of 3 with amines gave the corresponding alkylamines 6 and 7. Reaction of 3 with hydrazine and acetamidine hydrochloride gave pyrazole derivative 8 and pyrimidine derivative 9, respectively.
Reaction of 3‐methylindole and 2,3‐dimethylindole with dimethyl acetylenedicarboxylate using boron trifluoride‐diethyl ether catalysis
Authors: Rodrigues J.Augusto R. , Verardo L. I. 
Published: March 2009

AbstractReactions of dimethyl acetylenedicarboxylate with 3‐methylindole and 2,3‐dimethylindole under boron trifluoride‐diethyl ether catalysis were carried out at low temperature (0–25°). Thermally unstable cyclobutenes were isolated, mainly in apolar solvents, which isomerized to benzazepines. The other compounds isolated were Michael adducts and dihydro‐2‐oxocarbazoles.