bluuebunny/crossref_metadata_2025 huggingface dataset:
A facile one‐pot synthesis of 2,5‐disubstituted oxazoles using iodobenzene diacetate
Authors: Varma Rajender S. , Kumar Dalip
Published: March 2009

A facile one‐pot synthesis of oxazoles 1a‐h is described that utilizes readily available aromatic α‐methyl ketones and a safe hypervalent iodine reagent, iodobenzene diacetate.
Manganese triacetate oxidation of phenolic schiffs bases: Synthesis of 2‐arylbenzoxazoles
Authors: Varma Rajender S. , Kumar Dalip
Published: March 2009

A concise synthesis of 2‐arylbenzoxazoles, 5a‐f, is described that occurs via the oxidative cyclization of Schiff's bases, 1a‐f, using relatively benign reagent, manganese triacetate.
Structure and properties of ethyl (2‐benzimidazolyl)cyanoacetimidate
Authors: Yamaguchi Yoshimi , Okamoto Yoshihisa , Harada Kazuho
Published: March 2009

The revision of the structure of hydrolytic product from 4‐cyano‐1‐ethoxypyrirnido[1,6‐a]benzimidazole (1) and the properties of ethyl (2‐benzimidazolyl)cyanoacetimidate (3a) are described.
Successive electron transfer reaction of the lithium salt of 5‐methyl‐5,10‐dihydrophenazine anion with 4‐nitrophenethyl bromide via 4‐nitrostyrene
Authors: Sugimoto Akira , Maruyama Hideyuki , Takahashi Wataru , Mizuno Kazuhiko , Uehara Kaku , Adachi Tomohiro
Published: March 2009

The reaction of lithium salt of 5‐methyl‐5,10‐dihydrophenazine anion with 4‐nitrophenethyl bromide in 1,2‐dimethoxyethane gave unexpected compounds, 1,2‐bis[5‐(10‐methyl‐5,10‐dihydrophenazinyl)]‐1‐(4‐nitrophenyl)ethane and 1,4‐bis(4‐nitrophenyl)‐1,4‐bis[5‐(10‐methyl‐5,10‐dihydrophenazinyl)]butane, while the reaction in dimethyl sulfoxide brought about the formation of 5‐methyl‐10‐(4‐nitrophenethyl)‐5,10‐dihydrophenazine. The successive electron transfer mechanism is proposed for the former reaction via 4‐nitrostyrene.
Reactions of arylglyoxals with tetrasulfur tetranitrides (S4N4): Formation of 2‐aroyl‐5‐arylimidazoles and 2‐aroyl‐5‐aryloxazoles
Authors: Kong Yung Cheol , Kim Kyongtae
Published: March 2009

Treatment of arylglyoxal monohydrates with tetrasulfur tetranitride in p‐dioxane at reflux afforded 2‐aroyl‐5‐arylimidizoles and 2‐aroyl‐5‐aryloxazoles in 10 to 31% and 17 to 32% yields, respectively. With non‐hydrate of arylglyoxals, yields of the latter increase somewhat, whereas essentially no changes in yields of the former were observed. A mechanism is proposed for the formation of the products.
Synthesis and conformational analysis of a chiral fluorinated bilirubin analog lacking carboxyl groups
Authors: Boiadjiev Stefan E. , Lightner David A.
Published: March 2009

An optically active analog 1 of etiobilirubin‐IVγ with a single fluorine on each of the C(8) and C(12) alkyl groups has been synthesized in order to examine its potential for hydrogen bonding with fluorine. Circular dichroism spectroscopy reveals an unusually strong influence of 2,2,2‐trifluoroethanol solvent on diastereo‐selection of the M‐helical conformation of (81S,121S)‐1.
1,6‐ and 1,7‐naphthyridines. II. Synthesis from acyclic precursors
Authors: Blanco M. Mercedes , Perillo Isabel A. , Schapira Celia B.
Published: March 2009

A number of 8‐hydroxy‐6‐methyl‐1,6‐naphthyridin‐5(6H)‐one‐7‐carboxylic acid alkyl esters 3 and the isomeric 5‐hydroxy‐7‐methyl‐1,7‐naphthyridin‐8(7H)‐one‐6‐carboxylic acid alkyl esters 4 were synthesized from acyclic precursors obtained starting from quinolinic anhydride 5. Thus, methanolysis of 5 afforded the hemiester 6 which treated with oxalyl chloride and sarcosine ethyl ester gave 3‐(N‐ethoxycarbonylmethyl‐N‐methylcarbamoyl)pyridine‐2‐carboxylic acid methyl ester 8. Compound 8 was cyclized to naphthyridines 3a‐e with sodium alkoxides. The isomeric naphthyridines 4a‐c were obtained by cyclization of the open intermediary 2‐(N‐ethoxycarbonylmethyl‐N‐methylcarbamoyl)pyridine‐3‐carboxylic acid methyl ester 9 obtained by a route that involves treatment of 5 with sarcosine ethyl ester and esterification with diazomethane. Spectroscopic properties (1H nmr, uv, ir) of compounds 3 and 4 are discussed and confirmed the proposed structures.
Pyridazine derivatives. XIX: Functionalization studies at the 5 position in the 6‐phenyl‐3(2H)‐pyridazinone system
Authors: Sotelo Eddy , Raviña Enrique , Estevez Isabel
Published: March 2009

A series of 6‐phenyl‐3(2H)‐pyridazinones bearing different substitution at the 5 position of the pyridazinone ring were prepared in the search for new platelet aggregation inhibitors. The structure of the final compounds was determined on the basis of spectroscopics methods.
Intramolecular oxidative cyclizations in heteroarylthioureas: A versatile pathway to bridgehead heterocyclic systems
Authors: Castro Ana , Martinez Ana
Published: March 2009

Intramolecular oxidations in N‐alkyl‐N'‐heteroarylthioureas represent a facile and versatile synthetic pathway to fused heterocyclic systems including the bridgehead ones. This kind of heterocycles are the main feature in commom biologically active compounds.
Synthesis of 3‐phenoxy‐1,3‐dihydro‐1‐isobenzofuranones by palladium‐catalyzed carbonylative cyclization of 2‐bromobenzaldehyde with phenols
Authors: Cho Chan Sik , Baek Dong Yeol , Shim Sang Chul
Published: March 2009

2‐Bromobenzaldehyde reacts with phenols in acetonitrile under carbon monoxide pressure in the presence of a catalytic amount of bis(triphenylphosphine)palladium(II) chloride to afford the corresponding 3‐phenoxy‐1,3‐dihydro‐1‐isobenzofuranones in high yields.
The directed ortho metalation — Cross‐coupling symbiosis in heteroaromatic synthesis
Authors: Green Laine , Chauder Brian , Snieckus Victor
Published: March 2009

Thirty years after its discovery by Gilman and Wittig, the Directed ortho Metalation (DoM) reaction continues to march in synthetically useful paths. To offer evidence for this statement, this lecture review describes a new and general cumyl Directed Metalation Group (DMG) (Schemes 2–6) and a phosphine oxide DMG (Schemes 7 and 8). Aryl‐aryl cross‐coupling chemistry is highlighted by polymer support Suzuki‐Miyaura (Schemes 10 and 11) and an aryl O‐carbamate‐Grignard of value in the construction of naphthalenes (Scheme 12) and indoles (Scheme 13) and, for the latter class of compounds, in the generation of 4,5‐quinodimethane intermediates (Scheme 14) for the synthesis of corresponding annelated derivatives (Scheme 15). The marriage of DoM with the Negishi cross‐coupling reaction is demonstrated in general (Scheme 16). The concept of Directed remote Metalation (DreM) (Schemes 17 and 19) is applied to the synthesis of dibenzopyranones (Scheme 18), xanthones (Scheme 21), acridones, dibenzoazepinones, and oxindoles (Scheme 20). In this context, a carbanionic N‐to‐ortho‐C t‐Boc migration leading to anthranilate esters is also achieved (Scheme 20). For provision of diaryl ethers, diaryl sulfides, and diaryl amines, a new copper catalyst is introduced into the venerable Ullmann reaction (Scheme 22) and its extension by DoM, and cross‐coupling chemistry is indicated (Scheme 23). A recently evolving link to DoM, the Grubbs metathesis process is manifested in the total synthesis of two natural products (Schemes 25 and 26) and has anticipated use more broadly in heterocyclic synthesis. (Scheme 27).
Metal promoted synthesis of heterocycles from heteroacyclic compounds
Authors: Yamamoto Yoshinori
Published: March 2009

New synthetic methods, based upon metal mediated or catalyzed C‐C/C‐O/C‐N bond formation, for heterocycles and their application to natural product syntheis are described.
Synthesis of two 1,3‐2,4‐calix[4]bis‐crown ethers containing two 1,2‐phenylene and one pyridine or anisole units in each crown ether moiety
Authors: Xue Guo‐Ping , Bradshaw Jerald S. , Su Ning , Krakowiak Krzysztof E. , Savage Paul B. , Izatt Reed M.
Published: March 2009

Syntheses of 1,3–2,4‐calix[4]bis‐crown ethers (1 and 2) fixed in the 1,3‐alternate conformation by 1,3‐ and 2,4‐bridges made of two modified polyether chains each containing two 1,2‐phenylene residues and one pyridine or anisyl unit are reported. The structures of compounds 1 and 2 were established by 1H nmr, 13C nmr, hrms and elemental analyses.
Isolation and structural data of the opened ring derivative of a 1,2,4‐triazolothieno‐1,4‐diazepine
Authors: Legouin Béatrice , Burgot Jean‐Louis
Published: March 2009

The preparation of the trihydrochloride form of 2‐[3‐(aminomethyl)‐5‐methyl‐1,2,4‐triazol‐4‐yl]‐3‐(2‐chlorobenzoyl) thieno[2,3‐c]‐4,5,6,7‐tetrahydropyridine (2) the ring opened derivative of a 1,2,4‐triazolo‐thieno‐1,4‐diazepine is described. Its structural properties are given, and are compared with those of the corresponding closed form 4H‐6‐(2‐chlorophenyl)‐1‐methyl‐7,8,9,10‐tetrahydropyrido[4′,3′:4,5]thieno[3,2‐f]‐[1,2,4]triazolo[4,3‐a][1,4]diazepine (1).
Syntheses of some new coumarin‐quinolone carboxylic acids
Authors: Trkovnik Mladen , Ivezić Zrinka
Published: March 2009

Aminocoumarin derivatives 3‐10 were condensed with diethyl ethoxymethylenemalonate to give intermediates 11‐18. Thermal cyclizations of intermediates give benzopyranopyridinecarboxylates 19‐26. These esters were hydrolyzed to the corresponding benzopyranopyridine carboxylic acids 27‐34.
Synthesis of some novel derivatives of 1,10‐phenanthroline
Authors: Garas Adel M. S. , Vagg Robert S.
Published: March 2009

The synthesis is described of a set of new N‐heterocyclic compounds which are derivatives of 1,10‐phenanthroline. The compounds are designed to be general purpose chelating agents which could function as tri‐, tetra‐ or hexadentate ligands with transition metal ions. Fused‐ring molecular components have been included in the design of the compounds so that they may function as binding agents to DNA through intercalation. This includes the synthesis of substituted derivatives of pyrazino[2,3‐f][1,10]phenanthroline and dipyrido[3,2‐a:2′3′‐c]phenazine.
New routes to 1‐functionally substituted arylbenzotriazoles: 3‐Benzotriazol‐1‐yl‐pyridazine‐4‐ones, 5‐benzotriazol‐1‐yl‐pyridazine‐6‐ones and 5‐benzotriazol‐1‐yl‐pyridazine‐6‐imines
Authors: Al‐Omran Fatima , Al‐Awadl Nouria , Yousef Osama , Elnagdi Mohamed Hilmy
Published: March 2009

Condensation of 1‐arylhydrazono‐1‐benzotriazol‐1‐yl 2‐propanones (5a‐c) with DMF DMA afforded 1‐aryl‐3‐benzotriazol‐1‐yl‐1,4‐dihydropyridazine‐4‐ones (8a‐c). While condensation of 1‐functionally substituted methylbenzotriazoles 3b,c with 2‐arylhydrazono‐3‐oxoarylpropanal 13a,b give 3‐aroyl‐5‐(benzo‐triazolyl‐1‐yl)‐1,6‐dihydro‐1‐phenylpyridazine‐6‐ones and 6‐imines 14a‐d.
The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 21. Naphtho[2′,1′:4,5]thieno[2,3‐c]naphtho[1,2‐f]‐quinoline, naphtho[2′,1′:4,5]thieno[2,3‐c]naphtho[1,2‐f][1,2,4]‐triazolo[4,3‐a]quinoline and naphtho[2′,1′:4,5]thieno[2,3‐c]naphtho[1,2‐f]‐tetrazolo[1,5‐a]quinoline
Authors: Luo Jiann‐Kuan , Federspiel Ronald F. , Castle Raymond N.
Published: March 2009

Photocyclization of 3‐chloro‐N‐(3‐phenanthryl)naphtho[1,2‐b]thiophene‐2‐carboxamide (12) furnished only one of the two possible isomers, i.e., naphtho[2′,1′:4,5]thieno[2,3‐c]naphtho[1,2‐f]quinolin‐6(5H)‐one (13), which was further elaborated to yield the unsubstituted ring system 7, its triazole 8 and tetrazole 9. The structural confirmation of 7 was accomplished by the total assignment of its 1H and 13C nmr spectra utilizing the concerted two‐dimensional nmr spectroscopic experiments.
An improved synthesis of 2‐amino‐5‐[(4‐chlorophenyl)thio]‐4‐morpholinopyrimidine (BW 394U) — A potential antisenility agent
Authors: Samano Vicente , Styles Virgil L. , Chan Joseph H.
Published: March 2009

This paper describes the synthesis of 2‐amino‐5‐[(4‐chlorophenyl)thio]‐4‐morpholinopyrimidine (BW 394U, compound 4), a potential antisenility agent. The key intermediates 3a/3b were obtained from an in situ‐generated Vilsmeier‐Haack reagent that simultaneously protected the 2‐amino group prior to further manipulations. Displacement of the chloro group in 3a gave 4 in 40% yield and 4‐dimethylamino analogue 5. However, displacement of 3b with morpholine followed by treatment with aqueous base gave 4 in 74% yield.
Biologically active 1‐arylpiperazines. Synthesis of N‐[3‐(4‐aryl‐1‐piperazinyl)propyl] derivatives of benzoxazinone and benzoxazolinone
Authors: Kowalski Piotr , Majka Zbigniew , Kowalska Teresa , Mokrosz Maria J. , Duszynska Beata
Published: March 2009

The synthesis of new N‐[3‐(4‐aryl‐1‐piperazinyl)propyl] derivatives of 1H‐2,4‐benzoxazin‐3(4H)‐one (1a‐b), 2H‐1,4‐benzoxazin‐3(4H)‐one (2a‐b, 3a‐b and 4b), and benzoxazolin‐2‐one (5a‐b), as biologically active agents, is described.
The reaction of 2,4,5,6‐tetraaminopyrimidine with chalcones
Authors: Insuasty Braulio , Pérez Alfredo , González Diego , Quiroga Jairo , Meier Herbert
Published: March 2009

The reaction of the tetraaminopyrimidine 1 with the chalcones 2a‐f yields, in the presence of catalytic amounts of acetic acid, the 1H‐pyrimido[4,5‐b][1,4]diazepine derivatives 3a‐f. The cyclization process consists of a condensation reaction and a Michael type addition.
Studies on pyrrolidinones. Synthesis and cyclization of N‐[α‐naphthyl‐(3,4,5‐trimethoxyphenyl)‐methyl]pyroglutamic acid
Authors: Legrand Anne , Rigo Benoît , Hénichart Jean‐Pierre , Norberg Bernadette , Camus Fabrice , Durant FranÇOis , Couturier Daniel
Published: March 2009

Condensation of trimethoxyphenyl naphthylcarbinol trimethylsilyl ether with methyl N‐trimethylsilyl‐pyroglutamate yields two separable esters. The Friedel‐Crafts cyclization of the acids obtained after saponification gives analogs of azapodophylloxin. Reduction and treatment of the obtained products with hydrobromic acid yields analogs of azatoxin.
Synthesis of vinca alkaloids and related compounds part 94. Epimerization of compounds with aspidospermane and D‐secoaspidospermane skeleton
Authors: Kalaus György , Szabó Lajos , Éles János , Szántay Csaba , Juhász Imre , Greiner IstvÁn , Brlik János , Kajtár‐Peredy Mária
Published: March 2009

The individual epimerization steps of vincadifformine (1), deethylvincadifformine isomers (2,3), their synthetic intermediates (4–13) as well as that of simpler compounds with D‐secoaspidospermane skeleton (15–17) were studied a) in protic medium (boiling deuteroacetic acidic) and b) under reductive (with sodium borodeuteride in boiling acetic acid, or with sodium borohydride in boiling deuteroacetic acid) conditions.
The photochemistry of 6‐phenanthridinecarbonitrile I. Product analysis
Authors: Vittimberga Bruno M. , Sears Donald F.
Published: March 2009

When 6‐phenanthridinecarbonitrile (3) is irradiated at 2537 Å in neutral 9:1 2‐propanol/water, three major products are formed. These are dimethyl‐(6‐phenanthridinyl)methanol (4), phenanthridine (5) and 6,6′‐biphenanthridine (6). When benzophenone is present in the reaction mixture, diphenyl‐(6‐phenanthridinyl)‐methanol is also formed. 6‐Phenanthridinyl radical which is common to the formation of all these products, is formed by a monophotonic process involving hydrogen atom abstraction from an alcohol molecule by an excited state of 3. Unlike what is generally found with other nitrogen‐heterocycles, the photochemistry of 3 appears to involve only a π,π* singlet state. The fluorescence of 3 is quenched with the triplet quencher cis/trans‐piperylene as a function of the concentration of the diene without the accompaniment of an exci‐plex emission.
New 1,8‐peri‐annelated tricyclic quinolone antibacterials
Authors: Miao H. , Cecchetti V. , Tabarrini O. , Fravolini A.
Published: March 2009

The synthesis of new tricyclic quinolones, resulting from peri‐annelation of 1,2,4‐oxadiazine moiety at the N‐1/C‐8 position of the pharmacophoric quinolone nucleus, are described. None of the synthesized compounds showed interesting antibacterial activity in vitro against the tested strains, with the exception of Klebsiella pneumoniae which was susceptible to all the compounds at MIC values of 8 μg/ml.
Reactions of 3‐methylamino‐5‐phenylthiophene with α,β‐unsaturated esters and α,β‐unsaturated nitriles
Authors: Lee Jong Seok , Kim Kyongtae
Published: March 2009

Treatment of 3‐methylamino‐5‐phenylthiophene with α,β‐unsaturated esters, i.e., methyl acrylate, (E)‐methyl crotonate, diethyl fumarate, diethyl maleate and ethyl propiolate, in tetrahydrofuran for several days at reflux gave 1‐methyl‐3,4‐dihydrothieno[2,3‐e]pyridin‐2‐ones 4 and/or 1‐methylthieno[2,3‐e]pyridin‐2‐ones 5, depending on the structure of the esters. On the other hand, the same reactions with α,β‐unsaturated nitriles such as acrylonitrile and tetracyanoethene, gave the corresponding thiophenes 7 and 10 bearing 2‐cyanoethyl and 1,2,2‐tricyanoethenyl groups at C‐2, respectively. The reaction with (Z)‐1,2‐dicyanoethene under the same conditions produced the corresponding thiophene 9 bearing the 1,2‐dicyanoethenyl group and 1,2‐dicyano‐5‐methylaminobiphenyl.
Synthesis of a novel purine‐containing heterocyclic ring system: 8,10‐Dimethylindolo[2′,3′:5,6][1,2,4]triazino[4,3‐f]purine‐9,11(8H, 10H, 13H)‐dione
Authors: Da Settimo Antonio , Primofiore Giampaolo , Da Settimo Federico , Simorini Francesca , Marini Anna Maria , La Motta Concettina , Taliani Sabrina
Published: March 2009

The preparation of a novel purine containing heterocyclic ring system, indolotriazinopurine, by the condensation of 8‐hydrazinotheophylline with 5‐substituted isatins via the intermediate hemiaminal and hydrazone derivatives, is described.
Activated carbonyl species for the preparation of ortho‐acylarylsydnones
Authors: Turnbull Kenneth , Beladakere Ravindra N. , Mccall Neal D.
Published: March 2009

ortho‐Acylarylsydnones can be prepared in moderate to good yield by the action of nucleophiles upon suitable activated carbonyl species.
Synthesis of 2,5‐bis‐arylpyridines by [4 + 2] cycloaddition of 1,4‐bis aryl‐2‐aza‐1,3‐butadienes with electron‐poor dienophiles
Authors: Paparin Jean‐Laurent , Crévisy Christophe , Grée René , Toupet Loïc
Published: March 2009

Tetrahydropyridines 4a, 4b, 4c and pyridines 7a, 7b, 7c, 9a, 9b, 9c were synthesized by a [4 + 2] cycloaddition between 1,4‐bis aryl‐2‐aza‐1,3‐butadienes and electron‐poor dienophiles. Dimeric cycloadducts 6a, 6b, 6c, were also isolated indicating a competition between the expected Hetero Diels‐Alder and a dimerization process.
Studies on pyrazines. 36. A novel synthesis of 6‐(2‐hydroxyethyl)‐1,3‐dimethyllumazine
Authors: Sato Nobuhiro , Ono Masahiro
Published: March 2009

The titled compound was synthesized by cycloaddition of 5,6,7,8‐tetrahydro‐5,7‐dimethyl‐3,6,8‐trioxo‐3H‐pyrimido[5,4‐c][1,2,5]oxadiazine (1) with 2,3‐dihydrofuran (2a).
Synthesis of heterocycles from molecular nitrogen as a nitrogen source
Authors: Mori Miwako
Published: March 2009

Nitrogen fixation is a very attractive process. We succeeded in nitrogen fixation using a TiCl4‐ or Ti(O‐i‐Pr)4‐Li‐TMSCl system. Nitrogen fixation proceeds at room temperature under 1 atmosphere pressure of nitrogen to give a mixture of titanium nitride complex 12, titanium nitrogen complex 13, and N(TMS)4. Using the titanium nitrogen complexes 1, various heterocycles were synthesized from the corresponding ketocarbonyl compounds. Nitrogen in air could be fixed using this method. The total syntheses of lycopodine and monomolin I were achieved from nitrogen in air as the nitrogen source. On the other hand, transmetalation of the nitrogen moiety of titanium nitrogen complexes 1 to a palladium complex was realized, and the non‐substituted anilines could be synthesized from ArX and N2 in the presence of the palladium catalyst. Furthermore, amide could be synthesized from ArX, CO, and N2 using the palladium catalyst.
Finding drug candidates in virtual and lost/emerging chemistry
Authors: de Laet Andy , Hehenkamp Jurriaan J. J. , Wife Richard L.
Published: March 2009

There are many opportunities for chemists to help make the drug discovery process more efficient. The virtual world of chemistry contains many challenges to the heterocyclic chemist but this world is very large and attention must be focused on the best candidates for synthesis and testing. The algorithm set SORT&gen makes it possible to form an opinion about the constitution of large compound collections. It also generates the ring scaffolds of the molecules that are missing in these collections. Its application in the drug discovery process is discussed and the smallest missing molecular scaffolds are presented.
2‐Triazolylpyrimido[1,2,3‐cd]purine‐8,10‐diones via 1,3‐dipolar cycloadditions to 2‐ethynylpyrimido[1,2,3‐cd]purine‐8,10‐dione
Authors: Simo Ondrej , Rybár Alfonz , Alföldi Juraj
Published: March 2009

This paper presents the synthesis of a series of 5,6‐dihydro‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ring system derivatives with a [1,2,3]triazole ring bonded in position 2. The procedure is based on cycloaddition of substituted alkyl azides to the terminal triple bond of 5,6‐dihydro‐2‐ethynyl‐9‐methyl‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione (4). This cycloaddition produced two regioisomers −5,6‐dihydro‐9‐methyl‐2‐(1‐substituted‐1H‐[1,2,3]triazol‐5‐yl)‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione (7) and 2‐(1‐substituted‐1H‐[1,2,3]triazol‐4‐yl) derivative 8. The required 2‐ethynyl deriva tive 4 was obtained from the starting 2‐unsubstituted compound 1 by bromination to yield the 2‐bromo derivative 2, which was converted by Sonogashira reaction to trimethylsilylethyne 3 and finally, the protective trimethylsilyl group was removed by hydrolysis.
A comparative study of the epoxidation of 2‐substituted isoflavones by dimethyldioxirane, sodium hypochlorite, and alkaline hydrogen peroxide (weitz‐scheffer reaction)
Authors: Lévai Albert , Patonay Tamás , Székely Andrea , Vass Erzsébet B. , Adam Waldemar , Jekö József
Published: March 2009

The comparative epoxidation of 2‐substituted isoflavones 9–16 has been conducted by the utilization of three different protocols, viz. epoxidation with isolated dimethyldioxirane (Method A), with sodium hypochlorite (Method B), and with alkaline hydrogen peroxide (Method C), to afford epoxides 17–24. Best results have been obtained with Method C (Weitz‐Scheffer epoxidation). The structures of epoxides have been assigned on the basis of nmr spectral and mass spectral data.
Addition reactions of allyl stannanes to an indolo[2′,3′:3,4]pyrido[1,2‐b]isoquinoline imminium salt
Authors: Unangst Paul C. , Bratton Larry D. , Connor David T. , Roth Bruce D. , Rubin J. Ronald , Trivedi Bharat K.
Published: March 2009

The addition of organometallic reagents to the 13b‐position of the indolo[2′,3′:3,4]pyrido[1,2‐b]isoquinoline imminium salt 4 is described. Reaction of 4 with tetraallyl tin in 2‐methoxyethanol gave the allyl adduct 7 in moderate yield. Further elaboration of 7 yielded the pentacyclic benzylidene alcohols 13 and 14. Structure elucidation of the compounds prepared was achieved by a combination of 1H nmr spec troscopy and X‐ray crystallography.
Synthesis of new tricyclic mesoionic amides via photochemical conversion of a 5‐azido‐1‐mesityl‐3‐phenyltetrazolium salt
Authors: Araki Shuki , Hattori Hiromi , Yamamura Hatsuo , Kawai Masao
Published: March 2009

New mesoionic amides 4 and 5 with novel tricyclic ring systems have been synthesized by the photolysis of a 5‐azido‐1‐mesityl‐3‐phenyltetrazolium salt 1c via the corresponding triplet nitrene inter mediate. The structure of 5 has been determined by X‐ray crystallography.
A kinetic study of the thermolysis of N‐crotyl substituted 1,2,4‐triazoles
Authors: Carlsen Per H. J. , Jørgensen Kåre B.
Published: March 2009

A kinetic study of the thermolysis of 4‐crotyl‐3,5‐diphenyl‐4H‐1,2,4‐triazole (1) in a melt of the neat compound was performed at temperatures in the range of 260–350 °C. The main products formed were 1‐crotyl‐3,5‐diphenyl‐1H‐1,2,4‐triazole (3) and 1‐(1‐methylallyl)‐3,5‐diphenyl‐1H‐1,2,4‐triazole (4) together with 3‐methyl‐2,6‐diphenylpyridine (2) and 3,5‐diphenyl‐1,2,4‐triazole (5). Products 2 and 5 were both formed preferentially from 3 and 4. In the melt was observed first order kinetics. Activation parameters for formation of 3 and 4 were determined. Product 3: Ea = 95 kJ/mole. Product 4: Ea= 145 kJ/mole.
New syntheses and spectral properties of pteridine‐related heterocycles from 2,5‐diamino‐3,6‐dicyanopyrazine
Authors: Shirai Kazuko , Fukunishi Koushi , Yanagisawa Atsushi , Takahashi Hiroshi , Matsuoka Masaru
Published: March 2009

The reaction of 2,5‐diamino‐3,6‐dicyanopyrazine (1) as a new pyrazine raw material with alkyl isocyanate in the presence of sodium hydride gave novel heptahydroirnidazo[4,5‐g]pteridine‐2,6,8‐trione (2), but with tertiary butyl isocyanate gave trihydroimidazo[4,5‐b]pyrazine‐2‐ones (3). Similar reaction of 1 with alkyl thioisocyanate followed by alkyl iodide gave tetrahydropyrimido[4,5‐g]pteridines (4). The reac tion of 1 with alkylamine gave the amine‐adduct of the cyano groups which was further reacted with arylaldehyde to give the pyrimido[4,5‐g]pteridine (10). The products prepared are all of interest as potential pesticides and fluorescent chromophores.
1‐(1,2,3‐triazol‐4‐yl)‐benzimidazolones, a new series of heterocyclic derivatives
Authors: Bertelli Lucia , Biagi Giuliana , Calderone Vincenzo , Giorgi Irene , Livi Oreste , Scartoni Valerio , Barili Pier Luigi
Published: March 2009

New 1‐(1,2,3‐triazol‐4‐yl)‐benzimidazolone derivatives were obtained on pursuing research about new tricyclic derivatives of medicinal interest, bearing a 1,2,3‐triazole ring fused with another heterocyclic ring. 1‐[(5‐Carboxamido)‐1,2,3‐triazol‐4‐yl]‐benzimidazolone was prepared by four different chemical routes and it was unequivocally confirmed by spectroscopic methods. Its chemical behaviour, was evaluated by some common chemical reactions such as hydrolysis, esterification, decarboxylation, nitration and N‐methylation.
Synthesis of pyrrolo[3′,4′:2,3]azepino[4,5,6‐cd]indole‐8,10‐diones
Authors: Mahboobi Siavosh , Eluwa Stella , Koller Markus , Popp Alfred , Schollmeyer Dieter
Published: March 2009

3‐Amino‐4‐(3‐indolyl)pyrrolin‐2,5‐diones are condensed with various aldehydes and ketones to the cor responding imines. Under Pictet‐Spengler conditions, the latter do not cyclize to pyrrolo‐β‐carbolines, but readily yield pyrrolo[3′,4′:2,3]azepino[4,5,6‐cd]indole‐8,10‐diones.
Haloacetylated enol ethers: 15. Study of the regiochemistry of the cyclo‐condensation of β‐alkoxyvinyl trihalomethyl ketones with N‐methyl thiourea
Authors: Zanatta Nilo , Madruga Claudia Da C. , Marisco Patricia Da C. , Flores Darlene C. , Bonacorso Helio G. , Martins Marcos A. P.
Published: March 2009

A study of the regiochemistry of the cyclo‐condensation reaction of ß‐alkoxyvinyl trihalomethyl ketones with an unsymmetric dinucleophile N‐methyl thiourea to afford a series of 1‐methyl‐3‐(4,4,4‐trifluoro[chloro]‐3‐oxo‐1‐butenyl)thioureas and the corresponding N‐methyl pyrimidinethione derivatives is reported. The absolute assignment of the position of the N‐methyl group in the pyrimidine ring was obtained through a nmr study based on two dimensional HMBC and NOESY experiments.
Studies with 1‐functionally substituted alkylbenzotriazoles: An efficient route for the synthesis of 1‐azolylbenzotriazoles, benzotriazolylazines and benzotriazolylazoloazines
Authors: Al‐Omran Fatima
Published: March 2009

A new approach to the synthesis of pyrazole, isoxazole, pyridine and pyrazolo[1,5‐α]pyrimidine deriva tives is reported. The structure of the newly synthesized compounds was elucidated by elemental analyses, ir and 1H nmr spectra, and in some cases by 13C nmr investigation.
Synthesis and characterization of new substituted terdentate 2,6‐bis(2′‐quinolinyl)pyridine and 1,3‐bis(2′‐quinolinyl)‐benzene ligands for transition metals
Authors: Mamo Antonino
Published: March 2009

A series of N‐N‐N terdendate polypyridine type ligands and their N‐C‐N cyclometalating homologues were synthetized and fully characterized (L1‐L12). Complete assignments of the 1H spectra of the various compounds, accomplished by using a combination of one‐ and two‐dimensional nmr techniques, and 13C data are also reported.
Thermal cyclization of 4‐azido‐3‐nitropyridines to furoxanes
Authors: Stadlbauer Wolfgang , Fiala Werner , Fischer Michaela , Hojas Gerhard
Published: March 2009

4‐Chloro‐3‐nitro‐2‐pyridines 3 and 10, obtained from 4‐hydroxy‐2‐pyridones 1 and 8 after nitration and chlorination, gave with sodium azide 4‐azido‐3‐nitropyridines 4 and 11, which cyclized on thermolysis to furoxans 6 and 12. Desoxygenation of the furoxan 6 with triphenylphosphane gave the furazan 7. Thermal decomposition conditions of the azide 4 and the desoxygenation reaction of 6 to 7 were studied by differ ential scanning calorimetry (DSC).
Synthesis of [1,2,5]selena(or thia)diazolo[3,4‐e][1,4]diazepines, [1,2,5]selena(or thia)diazolo[3,4‐e][1,4]oxazepines and [1,2,5]selena(or thia)diazolo[3,4‐c] [1,2,6]thiadiazines
Authors: Ueda Taisei , Doi Wataru , Nagai Shin‐Ichi , Sakakibara Jinsaku
Published: March 2009

Novel heterocycles [1,2,5]selenadiazolo[3,4‐e][1,4]diazepines 3a‐c, [1,2,5]thiadiazolo[3,4‐e]‐[1,4]diazepines 7a‐c, [1,2,5]selenadiazolo[3,4‐e][1,4]oxaepines 4a,b, [1,2,5]thiadiazolo[3,4‐e]‐[1,4]oxazepines 9a‐c and [1,2,5]selena(or thia)diazolo[3,4‐c][1,2,6]thiadiazines 10a,b were synthesized starting form 4,6‐dimethyl[1,2,5]se]enadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)‐dione 1 or 4,6‐dimethyl‐[1,2,5]thiadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)‐dione 5.
Synthesis and properties of some 2,3‐disubstituted 6‐fluoro‐7‐(4‐methyl‐1‐piperazinyl)quinoxalines
Authors: Abdel‐Jalil Raid J. , Al‐Qawasmeh Raed A. , Voelter Wolfgang , Heeg Peter , El‐Abadelah Mustafa M. , Sabri Salim S.
Published: March 2009

The 2,3‐disubstituted 6‐fluoro‐7‐(4‐methyl‐1‐piperazinyl)‐quinoxalines (3–11) were synthesized for bioassay via reaction of 1.2‐diamino‐4‐fluoro‐5‐(4‐methyl‐1‐piperazinyl)benzene (2) with the appropriate 1,2‐dicarbonyl compounds. However, none of the tested compounds 3–11 showed significant in vitro activ ity against E. coli ATCC11229, S. aureus ATCC6538 and C.albicans SATCC10231.
Synthesis of indole‐4‐carboxaldehydes and 4‐acetylindole from N‐alkyl‐5‐aminoisoquinolinium salts
Authors: Muchowski Joseph M.
Published: March 2009

N‐Alkyl‐5‐aminoisoquinolinium salts (8a‐d) are converted into indole‐4‐carboxaldehydes (1a‐c) on heating in a two phase alkyl acetate‐water system containing an excess of a 2:1 sodium bisulfite‐sodium sulfite mixture. 4‐Acetylindole 1e is prepared in the same way from 1‐methyl‐2‐cyanomethylisoquinolinium bromide 8f.
Nucleophilic addition to 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide
Authors: Xia Chizhong , Tang Yiqing , Zhou Peiwen
Published: March 2009

Reactions of the 1,2‐diaryl 4,5‐dihydroimidazolium, represented by 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide 1, with ethylenediamine afforded a benzylidyne unit transferred product, 2‐phenyl‐2‐imidazoline 2; a ring‐opened adduct 4 was produced when excess ethylenediamine was used. Reactions of 1 with hydroxylamine, malononitrile, and nitromethane anions produced ring‐opened products, 5, 7, and 8 respectively.
Preparation and structure elucidation of 1,6,9,13‐tetraoxadispiro(4.2.4.2)tetradecane
Authors: Gaede Bruce , Henry Rodger , Chamberlin Steven A.
Published: March 2009

The tricyclic title compound, a symmetrical dispiro oxygen heterocycle, was isolated as a byproduct in the hydrogenation of furfuryl alcohol in the presence of hydrochloric acid. NMR studies and single crystal X‐ray analysis have established the relative stereochemistry of the two ketal carbons. Formation of the observed trans stereoisomer under equilibrating conditions is attributed to the anomeric effect.
Lariat ether alcohols based on dibenzo‐16‐crown‐5
Authors: Bartsch Richard A. , Bitalac Leah P. , Cowey Charles L. , Elshani Sadik , Goo Mi‐Ja , Huber Vincent J. , Ivy Sheryl N. , Jang Youngchan , Johnson Russell J. , Kim Jong Seung , Luboch Elzbieta , Mcdonough Joseph A. , Pugia Michael J. , Son Byungki , Zhao Qiang
Published: March 2009

Synthetic routes to forty‐four dibenzocrown ether alcohols are reported. The new crown ether com pounds are based on a sym‐dibenzo‐16‐crown‐5 platform. Most have a hydroxy group and an alkyl, aryl, aralkyl, alkenyl, alkynyl, or perfluoroalkyl group on the central carbon of the three‐carbon bridge. Others have substituted benzene rings and either a hydroxy or ‐O(CH2)nOH group attached to the central carbon of the three‐carbon bridge.
Ring opening of cyclic ethers by sulfuric acid ‐ acetic anhydride
Authors: Tanoue Yasuhiro , Hamada Moritsugu , Kai Norihisa , Nagai Takeshi , Sakata Kazunori , Hashimoto Mamoru , Morishita Shin‐Ichi
Published: March 2009

Cyclic ethers such as tetrahydrofuran or tetrahydropyran were easily cleaved at room temperature by sulfuric acid ‐ acetic anhydride providing the corresponding diacetoxyalkanes in good yield. The ring opening was applicable to saturated cyclic ethers, regardless of the presence of substituent groups.
Synthesis of novel spiroazetidinones by selective lactam‐carbonyl cleavage in 1‐aryl/cyclohexyl‐3,3‐diphenyl‐1′‐(diphenylacetyl)spiro[azetidin‐2,3′‐indoline]‐2′,4‐diones
Authors: Singh Girija S.
Published: March 2009

Titled compounds undergo selective N‐C cleavage on treatment with sodium hydroxide in ethanol affording a series of novel isatin‐based spiroazetidinones.
The synthesis and crystal structure of 2,6,9‐trimethyl‐4,8‐dinitro‐2,6,9‐triazabicyclo[3.3.1]nona‐3,7‐diene
Authors: Ostercamp Daryl L. , Wiles Sarah
Published: March 2009

The first preparation of title compound 1 is accomplished. Its heterocyclic structure was characterized spectroscopically and by X‐ray structure analysis.
A facile synthesis of 3‐Substituted 5‐Oxo‐1,2,4‐thiadiazoles from amidoximes
Authors: Kohara Yasuhisa , Kubo Keiji , Imamiya Eiko , Naka Takehiko
Published: March 2009

The reaction of amidoximes 1 with 1,1′‐thiocarbonyldiimidazole (TCDI) followed by treatment with silica gel or boron trifluoride diethyl etherate (BF3·OEt2) provided 3‐substituted 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2 in moderate yields. The Lewis acids are considered to promote the rearrangement of the thioxocarbamate intermediates 5 to the thiol carbarn ate intermediates 7, which cyclize to afford 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2.
Synthesis of 1‐[(pyrazol‐3‐yl)methyl]pyridazin‐6‐ones
Authors: Chung Hyun‐A , Kang Young‐Jin , Kweon D. H. , Lee Woo Song , Yoon Yong‐Jin
Published: March 2009

This paper presents the synthesis of 1‐[(pyrazol‐3‐yl)methyl]pyridazin‐6‐ones from ethyl 4‐(4,5‐dichloro‐6‐oxopyridazin‐1‐yl)‐3‐oxobutanoate.
Synthesis and fluorescence properties of substituted 7‐aminocoumarin‐3‐carboxylate derivatives
Authors: Corrie John E. T. , Munasinghe V. Ranjit N. , Rettig Wolfgang
Published: March 2009

4‐Trifluoromethyl‐ or 6‐bromo‐substituted 7‐diethylaminocoumarin‐3‐carboxamide derivatives 2 and 3, each containing a maleimide have been synthesized as potential fluorescent labeling reagents for thiol groups in proteins and their fluorescence properties have been determined. The 4‐trifluoromethyl substituted compound 2 has a significantly greater Stokes shift than the comparable compound lacking this group, but both the new coumarins have low fluorescence quantum yields (ϕf). When a 4‐trifluoromethyl substituent is present, the 3‐carboxamide is unusually labile to hydrolysis. Bromination of ethyl 7‐diethylaminocoumarin‐3‐carboxylate 17 gave the 6‐ and 8‐bromo derivatives 18 and 19 respectively, and also the 8‐bromo‐7‐monoethylamino compound 20. ϕf for the latter compound is 100‐fold greater than for its diethylamino analogue 19. Fluorescence lifetime measurements support an interpretation based on the twisted intramolecular charge transfer (TICT) model to explain these large differences in ϕf.
Synthesis of 2,4‐diaminopyrrolo[2,3‐d]pyrimidines via thermal fischer indolization. Pyrazole formation with ytterbium triflate catalysis
Authors: Bundy Gordon L. , Schwartz Theresa M. , Palmer John R. , Banitt Lee S. , Watt William
Published: March 2009

The high‐yield synthesis of the 2,4‐diaminopyrrolo[2,3‐d] pyrimidine 4 (PNU‐87663) via a Bischler‐like alkylation‐cyclization sequence was reported earlier. We describe herein an alternative synthesis of this potent antioxidant and several analogs based on the thermal Fischer indolization, starting from hydrazino substituted pyrimidines 5 and 13. In several cases where the thermal Fischer indolization failed, attempts to catalyze the reaction with Lewis acids, especially ytterbium triflate, led to the surprising and unprecedented formation of pyrazolo[3,4‐d]pyrimidines, e.g. 1‐methyl‐3‐phenyl‐4,6‐di‐1‐pyrrolidinyl‐1H‐pyrazolo[3,4‐d]pyrimidine (24), with the loss of the elements of methane. Mechanistic details of this transformation remain to be investigated.
Conformationally constrained dipeptides. Obtention of enantiomerically pure 6‐acetamido‐5‐oxo‐1,2,3,5,6,7‐hexahydro‐3‐indolizine carboxylic acid
Authors: Millet Régis , Meulon Emmanuelle , Goossens Laurence , Houssin Raymond , Hénichart Jean‐Pierre , Rigo Benoît
Published: March 2009

The separation of a stereoisomeric mixture of esters 6, and the synthesis of the new enantiomerically pure unsaturated 6,5‐fused bicyclic lactam 2 are described. The key‐step involves trimethylsilyl iodide cleavage, without racemization, of a vinylogous carbamate. The cis N‐ acetylamino acid 2 is a new scaffold for the synthesis of rigid β‐turn mimetics.
Efficient synthesis of 3,5‐functionalized isoxazoles and isoxazolines via 1,3‐dipolar cycloaddition reactions of 1‐propargyl‐ and 1‐allylbenzotriazoles
Authors: Katritzky Alan R. , Button Martin A. C. , Denisenko Sergey N.
Published: March 2009

3‐Aryl‐5‐(benzotriazol‐1‐ylmethyl)‐ 10a‐f and 3‐p‐methoxyphenyl‐5‐(α‐benzotriazol‐1‐yl‐α‐ethoxymethyl)‐isoxazole (13) were prepared in high yields by 1,3‐dipolar cycloadditions of 1‐propargyl‐benzotriazole (5) and (α‐ethoxypropargyl)benzotriazole (8), respectively, with nitrite oxides 3a‐f (prepared in situ from benzohydroximoyl chlorides 2a‐f). The benzotriazol‐1‐ylmethyl moiety was further elaborated by sequential lithiation and reaction with aldehydes, alkyl halides and Michael acceptors. Similar 1,3‐cycloadditions using 1‐allylbenzotriazole (6) and 1‐(α‐ethoxyallyl)benzotriazole (7) afforded 3,5‐substituted isoxazolines 11b, f and 12 in excellent yields.
New fused pyrazines. Synthesis of pyrido[3′,2′:4,5]‐thieno[2,3‐e]pyrrolo[1,2‐a]pyrazine derivatives
Authors: El‐Kashef H. S. , El‐Dean A. M. Kamal , Geies A. A. , Lancelot J. C. , Dallemagne P. , Rault S.
Published: March 2009

The synthesis of the title compounds was achieved using the key intermediate ethyl 4,6‐dimethyl‐3‐(pyrrol‐1‐yl)thieno[2,3‐b]pyridine‐2‐ carboxylate 2. This latter compound was obtained via the interaction of the thienopyridine amino ester 1 with 2,5 dimethoxytetrahydrofuran in acidic medium.
Reactivity of N‐benzyl‐3‐nitrophthalimide: A facile access to isoindolo[1,2‐d][3,5]benzothiazocine derivatives
Authors: Chihab‐Eddine Abderrahim , Jilale Abderrahim , Daïch Adam , Decroix Bernard
Published: March 2009

A functionalized isoindolo[1,2‐d][3,5]benzothiazocine 2B has been synthesized in three steps from the nitro‐imide derivative 5. The key step of this sequence was the cyclization of the thioglycolic acid derivative 9 under acidic conditions. An evaluation of the reactivity of the imide 5 and the corresponding N‐acyliminium ion toward borohydride reduction, organometallic addition, Meyer‐Schuster rearrangement and intermolecular alkoxylation and thioalkoxylation reactions was reported.
The synthesis and first full structural elucidation of a benzotriazole azo dye
Authors: Graham Duncan , Kennedy Alan R. , Teat Simon J.
Published: March 2009

Although azo dyes containing benzotriazole are of interest as substrates for surface enhanced resonance Raman scattering, SERRS, little is known of their molecular structure due to their poor crystal growth properties. We recently synthesised a highly crystalline dihydroquinoline via an unusual condensation reaction and we report herein that the azo‐benzotriazole dye subsequently formed was sufficiently crystalline to allow structural elucidation using synchroton radiation. It was found that this benzotriazole dye exists as the unexpected 6‐isomer and the structure of the dihydroquinoline moiety changes markedly on coupling due to increased delocalisation.
Synthesis of novel aminothiopyran dicarboxylates
Authors: Finkelstein Bruce L. , Sethuraman Maya R.
Published: March 2009

A one step synthesis of previously unknown aminothiopyran dicarboxylates from readily available starting materials is described. The yields range from 33–74%.
Synthesis of 1‐substituted [1,2,3]triazolo[4,5‐d]pyridazines as precursors for novel tetraazapentalene derivatives
Authors: Ramanaiah K. C. V. , Stevens Edwin D. , Trudell Mark L. , Pagoria Philip F.
Published: March 2009

A series of 1‐substituted 4,5‐diformyl‐[1,2,3]triazole derivatives were prepared by 1,3‐dipolar cyclo‐addition of aryl azides with acetylene dicarboxaldehyde mono‐diethylacetal. The triazoles were readily converted into 1‐substituted [1,2,3]triazolo[4,5‐d]pyridazines in good yields. The 1‐(2‐nitrophenyl)‐[1,2,3]triazolo[4,5‐d]pyridazine was found to be a useful intermediate for the generation of the novel 5H‐benzo[1,2,3]triazolo[1′,2′:1,2]triazolo[4,5‐d]pyridazin‐6‐ium inner salt ring system.
New routes to the synthesis of pyridazinone, ethoxypyridine, pyrazole and pyrazolo[1,5‐a]pyrimidine derivatives incorporating a benzotriazole moiety
Authors: Al‐Omran Fatima , Abd El‐Hay Osama Yousef , Abou El‐Khair Adel
Published: March 2009

A new approach to the synthesis of pyridazinone, ethoxypyridine, pyrazole and 7‐aminopyrazolo‐[1,5‐a]pyrimidine derivatives. The structure of the newly synthesized compounds was elucidated by elemental analyses, ir, 1H nmr spectra and in some cases by 13C nmr investigations.
A new diaza‐18‐crown‐6 ligand containing two quinolin‐8‐ylmethyl side arms: Crystal structures and characterization of the ligand, the protonated ligand and its mononuclear barium(II) and dinuclear copper(II) complexes
Authors: Dalley N. Kent , Xue Guoping , Bradshaw Jerald S. , Zhang Xian Xin , Harrison Roger G. , Savage Paul B. , Krakowiak Krzysztof E. , Izatt Reed M.
Published: March 2009

A new 7,16‐bis(quinolin‐8‐ylmethyl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane ligand, L, has been prepared and its crystal structure reported. In addition, the structure of the protonated ligand H2L has been determined. H2L is of interest because of interatomic interactions between the ligand and perchlorate ions. The mononuclear Ba(II) (BaL), and dinuclear Cu(II) (Cu2L) complexes of L have been prepared and their crystal structures determined. Stability constants and other thermodynamic data valid in methanol at 23 or 25° for these and several other complexes of L have been obtained. Among the metal ions studied, L forms the most stable complex with Ba2+. In addition, L selectively binds Cu2+ over Ni2+ by about 3 orders of magnitude. Some of the complexes have been studied using nmr and uv‐vis spectroscopic techniques. Crystal data are given for L, space group, P21c, a = 8.8325(14) Å, b = 13.808(3) Å, c = 13.310(3) Å; β = 94.72(2)° Z=2, R = 0.0727; for H2L, space group, P21/c, a = 14.685(3) Å, b = 15.035(6) Å, c = 17.369(4) Å, β = 90.366(12)°, Z = 4, R = 0.0781; for BaL, space group, Pbcn, a = 17.314(3) Å, b = 9.539(2) Å, c = 22.081(3) Å, Z = 4, R = 0.0354; and for Cu2L, space group, Cc, a = 19.762(2) Å, b = 14.413(2) Å, c = 14.935(2) Å, β = 98.753(12)°, Z = 4, R = 0.0564. Cu2+ forms a hydroxo‐bridged dinuclear complex with L while Ba2+ forms a mononuclear complex with L in which its two side arms are not involved in complexation.
Synthesis of functionalized cyclic enamines from lithium alkylphenyl sulfones and N‐carbo‐tert‐butoxy lactams
Authors: Arias Luis A. , Arbelo David , Alzérreca Arnaldo , Prieto José A.
Published: March 2009

Alkylphenyl sulfones 3 are appropriate synthons for the synthesis of 2‐phenylsulfonyl alkylidene pyrro‐lidine or piperidine derivatives 1 in good to moderate yields. The lithium alkyl sulfones 4 are first reacted with the desired protected lactams and then subjected to acidic methanolysis to afford the unusual enam‐ines 1a‐e. NMR studies (COSY 1H‐1H, COSY 1H‐13C, NOE) showed the Z enamines to exist in a dynamic equilibrium with the corresponding imines 2. The stereochemistry of the described compounds was confirmed by molecular calculations.
Synthesis and structural analysis of 5‐cyanodihydropyrazolo[3,4‐b]pyridines
Authors: Quiroga Jairo , Cruz Silvia , Insuasty Braulio , Abonia Rodrigo , Cobo Justo , Sánchez Adolfo , Nogueras Manuel , Low John N.
Published: March 2009

Several new 3‐aryl‐5‐cyanopyrazolo[3,4‐b]pyridines were easily prepared from 3‐amino‐5‐arylpyrazoles and α‐cyanochalcones. Structural analysis using NMR solution studies revealed the 2H‐tautomers as the preferred tautomer in solution (DMSO‐d6). X‐ray diffraction confirmed the 2H‐tautomers as the unique tau‐tomer species in the crystalline state as well. Geometry optimization of 1H and 2H‐tautomers at semi‐empirical levels (AM1, MINDO/3) were performed, indicating that in all cases the 2H‐tautomers are more stable than the corresponding 1H‐tautomers.
Pyridazines 92. Synthesis of dialkyldipyridazinodiazepinones as potential HIV‐1 reverse transcriptase inhibitors
Authors: Heinisch Gottfried , Matuszczak Barbara , Spielmann Elisabeth , Witvrouw Myriam , Pannecouque Christophe , De Clercq Erik
Published: March 2009

Two methods for the preparation of dialkylsubstituted dipyridazino[4,3‐b:3′,4′‐e][1,4]diazepinones and dipyridazino[3,4‐b:3′,4′‐e][1,4]diazepinones are reported. The new compounds were evaluated for their inhibitory effects against the replication of human immunodeficiency virus [HIV‐1(IIIB) and HIV‐2(ROD)] in MT‐4 cells.
Oxidation of 7,8‐diaminotheophylline with lead tetraacetate and reaction of the oxidation product, 6‐cyanoimino‐5‐diazo‐1,3‐dimethylpyrimidine‐2,4‐dione with alcohols or amines
Authors: Ueda Taisei , Yatsuzuka Naoyoshi , Nagai Shin‐Ichi , Okada Kumiko , Takeichi Emi , Segi Hiromi , Sakakibara Jinsaku
Published: March 2009

Oxidation of 7,8‐diaminotheophylline (1) with lead tetraacetate in refluxing toluene gave a mixture of 3‐amino‐5,7‐dimethylpyrimido[4,5‐e][1,2,4]triazine‐6,8‐dione (2) and 6‐cyanoimino‐5‐diazo‐1,3‐dimethylpyrimidine‐2,4‐dione (4). The latter was transformed to 2 by the reaction with 1‐propanethiol in quantitative yield. The reaction of 4 with methanol, ethanol and 1‐propanol in the presence of rhodium (II) acetate gave 5‐alkoxy‐6‐(2‐alkyl‐3‐isoureido)‐1,3‐dimethylpyrimidine‐2,4‐diones (7a‐c). A similar reaction of 4 with alkylamines such as n‐propylamine, n‐butylamine, isobutylamine and n‐hexylamine gave a mixture of 7‐alkyl‐8‐aminotheophyllines (8a‐d) and (5‐alkylamino‐1,3‐dimethyl‐2,4‐dioxopyrimidin‐6‐yl)cyanamides (9a‐d).
Design and synthesis of some new pyranoxanthenones with cytotoxic activity
Authors: Ghirtis Konstantinos , Pouli Nicole , Marakos Panagiotis , Skaltsounis Alexios‐Leandros , Leonce Stephane , Atassi Ghanem , Caignard Daniel H.
Published: March 2009

As part of a research program directed towards the design and synthesis of pyranoxanthones structurally related to acronycine, we present here the synthesis and cytotoxic activity of the pyranoxanthones 3 and 4 (X= H, Br; R= H, OMe; R'= H, Ac). Some of these compounds inhibit L1210 cell proliferation.
Bifunctional coumarin derivatives in solution and solid phase synthesis of fluorogenic enzyme substrates
Authors: Charitos Christos , Kokotos George , Tzougraki Chryssa
Published: March 2009

The use of the fluorescent bifunctional compounds 7‐amino‐4‐coumarinyl‐acetic acid 1, 7‐hydroxy‐4‐coumarinyl‐acetic acid 2 and ethyl 7‐amino‐4‐coumarinyl‐acetate 3 in solution and solid phase synthesis of fluorogenic enzyme substrates was examined. The intramolecularly quenched fluorogenic substrate N‐(7‐amino‐4‐coumarinyl‐acetyl)‐L‐phenylalanyl‐p‐nitroanilide 5, and the fluorogenic one ethyl 7‐(glutaryl‐L‐phenylalanilamido)‐4‐coumarinyl‐acetate 8, both suitable for chymotrypsin and/or chymotrypsin like enzymes determination, were prepared in solution. The substrates 7‐oleyloxy‐4‐coumarinyl‐acetic acid 13 and 7‐palmitoyloxy‐4‐coumarinyl‐acetic acid 14, suitable for the enzymatic study of lipases, were prepared by solid phase technique using 2‐chloro‐chlorotrityl‐resin. The study of the fluorescence properties of the fluorophores 1, 2, 3, and substrates 5, 8,13,14 showed that the examined bifunctional coumarin derivatives are suitable markers for solution and solid phase synthesis of fluorogenic enzyme substrates.