bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of some novel halogenated 2,4‐diaminoquinazolines
Authors: Tomažič Alenka , Hynes John B. 
Published: March 2009

AbstractThree new 2,4‐diaminoquinazolines, the 5,6‐difluoro, 6,7‐difluoro and 7,8‐difluoro isomers were prepared by the reaction of the requisite trifluorobenzonitrile and guanidine carbonate. Surprisingly, 2,3,6‐trifluorobenzonitriles gave 2,4‐diamino‐5,6‐difluoroquinazoline exclusively as determined by high resolution nuclear magnetic resonance spectroscopy. On the other hand, 3‐amino‐2,6‐difluorobenzonitrile on reaction with guanidine carbonate yielded only 5‐fluoro‐2,4,8‐triaminoquinazoline. This compound was subsequently converted to 8‐chloro‐2,4‐diamino‐5‐fluoroquinazoline using the Sandmeyer procedure. The nitration of 2,4‐diamino‐8‐fluoroquinazoline occurred exclusively at position six yielding 2,4‐diamino‐8‐fluoro‐6‐nitroquinazoline, which upon reduction with stannous chloride afforded 8‐fluoro‐2,4,6‐triaminoquinazoline. In a similar fashion 7‐fluoro‐2,4‐diaminoquinazoline underwent nitration at position six and was then reduced to give 7‐fluoro‐2,4,6‐triaminoquinazoline. Finally, both of these triaminoquinazolines were converted to the 6‐chloro derivatives under Sandmeyer conditions to yield 6‐chloro‐2,4‐diamino‐8‐fluoroquinazoline and 6‐chloro‐2,4‐diamino‐7‐fluoroquinazoline, respectively.
Photochemical induced formation of α‐alkylamino or alkylaminyl radicals from secondary amines: Reaction with 4‐pyridinecarbonitrile
Authors: Caronna Tullio , Morrocchi Sergio 
Published: March 2009

AbstractThe direct photolysis at 254 nm of 4‐pyridinecarbonitrile in the presence of some aliphatic secondary amines brought to the substitution of the CN group and to the formation of 4‐α‐alkylaminopyridines, whereas the irradiation in the presence of benzophenone at 350 nm yields 4‐alkylaminylpyridines and 4‐diphenylketylpyridine. A mechanism is proposed to explain the different course of the reaction under the two different conditions.
Synthesis of 7‐hydroxythioridazine and 7‐hydroxysulforidazine
Authors: Singh Shyam K. , Patrick Kennedy S. 
Published: March 2009

AbstractThe thioridazine metabolites 7‐hydroxythioridazine(2a)and 7‐hydroxysulforidazine(2b)were synthesized. Commercial 4‐chloro‐3‐nitrophenylmethylsulfone was converted to the corresponding 4‐thiol through an intermediate xanthate ester. Subsequent zinc metal reduction provided the 3‐amino thiolate. This salt was condensed with chloroquinone to yield 7‐hydroxy‐2‐methylsulfonylphenothiazine which was then protected as the isopropyl ether.N‐Alkylation with 2‐(2‐chloroethyl)‐1‐methylpiperidine using sodium hydroxide, then ether cleavage, afforded2b. TheN‐alkylation followed by reduction with diisobutylaluminum hydride and deblocking yielded2a. These reference standards will assist in an exploration of the potential role of meta‐bolically formed2aand2bin the neuroleptic response to thioridazine.
Reaction of 6‐chloro‐2‐[1‐methyl‐2‐(N‐methylthiocarbamoyl)]‐hydrazinoquinoxaline 4‐oxide with dimethyl acetylenedicarboxylate
Authors: Kurasawa Yoshihisa , Katoh Ritsuko , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa 
Published: March 2009

AbstractThe reaction of 6‐chloro‐2‐(1‐methylhydrazino)quinoxaline 4‐oxide 4a with methyl or phenyl isothiocyanate gave 6‐chloro‐2‐[1‐methyl‐2‐(N‐methylthiocarbamoyl)hydrazino]quinoxaline 4‐oxide 7a or 6‐chloro‐2‐[1‐methyl‐2‐(N‐phenylthiocarbamoyl)hydrazino]quinoxaline 4‐oxide 7b, respectively, whose reaction with dimethyl acetylenedicarboxylate afforded 6‐chloro‐2‐[N‐methyl‐N‐(5‐methoxycarbonylmethylene‐3‐methyl‐4‐oxo‐2‐thioxoimidazolidin‐1‐yl)]aminoquinoxaline 4‐oxide 8a or 6‐chloro‐2‐[N‐methyl‐N‐(5‐methoxycarbonylmethylene‐4‐oxo‐3‐phenyl‐2‐thioxoimidazolidin‐1‐yl)]aminoquinoxaline 4‐oxide 8b, respectively.
A convenient synthesis of new heterocycles from benzimidazoles and carbon suboxide
Authors: Bonsignore Leonardo , Loy Giuseppe , Secci Daniela 
Published: March 2009

AbstractThe reaction of carbon suboxide with 2‐substituted benzimidazoles was investigated. By this reaction 1,3‐diazino‐ (pyrimido‐), 1,3‐oxazino‐ and 1,3‐thiazinobenzimidazole‐1,3‐diones are obtained.
Synthesis of indeno[2,1‐b][1,4]benzothiazine derivatives from 2‐bromoinden‐1‐ones
Authors: Bajji Ashok C. , Nan'ya Seiko , Butsugan Yasuo 
Published: March 2009

Abstract2‐Bromoinden‐1‐ones 2 were condensed with 6‐substituted 3‐aminopyridine‐2(1H)‐thiones to produce a new type of 4‐azaindeno[2,1‐b][1,4]benzothiazine derivatives 3. Substituted 6‐phenylindeno[2,1‐b][1,4]benzothiazines 4 were also prepared by reacting 2‐bromo‐5‐methoxy‐ and 2,6‐dibromo‐5‐methoxyinden‐1‐ones with o‐aminobenzenethiol.
Syntheses of 4‐(benzo[b]furan‐2 or 3‐yl)‐ and 4‐(benzo[b]‐thiophen‐3‐yl)piperidines with 5‐HT2 antagonist activity
Authors: Watanabe Yoshifumi , Yoshiwara Hirotaka , Kanao Munefumi 
Published: March 2009

AbstractThe syntheses of 4‐(benzo[b]furan‐3‐yl)piperidines, 4‐(benzo[b]furan‐2‐yl)piperidines and 4‐(benzo[b]thiophen‐3‐yl)piperidines with 5‐HT2 antagonist activity are described. Reaction of 1‐acetyl‐4‐(2,4‐difluorobenzo‐yl)piperidine 2 with methyl glycolate gave methyl 6‐fluoro‐3‐(1‐acetylpiperidin‐4‐yl)benzo[b]furan‐2‐carboxylate 3, which was converted to 2‐[2‐[4‐(benzo[b]furan‐3‐yi)piperidin‐1‐yl]ethyl‐5,6,7,8‐tetrahydro‐1,2,4‐triazolo‐[4,3‐a]pyridin‐3(2H)‐one hydrochloride 9. Analogous benzo[b]furans 17a‐d and benzo[b]thiophenes 10a,b and 18a were prepared by a similar method. Cyclization of 4‐fluoro‐2‐(4‐pyridinylmethoxy)acetophenones 20a,b afforded 4‐(benzo[b]furan‐2‐yl)pyridines 21a,b, which were converted to 2‐[2‐[4‐(benzo[b]furan‐2‐yl)‐piperidin‐1‐yl]ethyl‐5,6,7,8‐tetrahydro‐1,2,4‐triazolo[4,3‐a]pyridin‐3(2H)‐one hydrochlorides 24a,b. Among them, benzo[b]furans 9 and 17a,d and benzo[b]thiophenes 10 and 18a showed potent 5‐HT2 antagonist activity in vitro.
Stereoselective synthesis of cis and trans 2‐substituted 1‐phenyl‐3‐azabicyclo[3.1.0]hexanes
Authors: Bonnaud Bernard , Bigg Dennis C. H. 
Published: March 2009

AbstractThe Stereoselective synthesis of cis and trans 2‐methyl‐1‐phenyl‐3‐azabicyclo[3.1.0]hexanes and 1,2‐diphen‐yl‐3‐azabicyclo[3.1.0]hexanes from 2‐oxo‐1‐phenyl‐3‐azabicyclo[3.1.0]hexane is described. The relative stereochemistry of the products was established by nuclear magnetic resonance and molecular modeling studies.
Synthesis of (1R,4R,7S)‐ and (1S,4S,7S)‐2‐(4‐tolylsulfonyl)‐5‐phenyl‐methyl‐7‐methyl‐2,5‐diazabicyclo[2.2.1]heptanes via regioselective opening of 3,4‐epoxy‐d‐proline with lithium dimethyl cuprate
Authors: Remuzon Philippe , Bouzard Daniel , Clemencin Claire , Dussy Christian , Essiz Munir , Jacquet Jean‐Pierre , Saint‐Germain Jean 
Published: March 2009

AbstractThe synthesis of (1S,4S,7S)‐ and (1R,4R,7S)‐2‐(4‐tolylsulfonyl>5‐phenylmethyl‐7‐rnethyl‐2,5‐diazabicyclo‐[2.2.1]heptanes (20) and (22) from trans 4‐hydroxy‐L‐proline is described.
Nitration of dithieno[3,2‐b:3′,2′‐d]pyridine and dithieno[3,2‐b:3′,4′‐d]pyridine
Authors: Szabó Kálmán J. , Gronowitz Salo 
Published: March 2009

AbstractNitration of dithieno[3,2‐b:3′,2′‐d]pyridine (4) and dithieno[3,2‐b:3′,4′‐d]pyridine (5) has been studied. Nitration of 4 occurred in both positions of the C ring, while 5 was predominantly substituted on the 3,4‐fused ring. The structures of the nitro derivatives were proven by extensive use of 1H and 13C nmr spectroscopy.
Preparation of some substituted imidazo[1,2‐a]pyridine derivatives
Authors: Shawcross Andrew P. , Stanforth Stephen P. 
Published: March 2009

Abstract2‐Bromopyridine derivatives 2a‐2c were prepared. Compounds 2b and 2c and ammonia yielded aminopyridines 3b and 3c which were converted to imidazo[1,2‐a]pyridine derivatives 4b and 4c. Compound 4b was nitrated giving the analogue 5b of metronidazole 1.
Convenient synthesis of 5‐azacoumarins
Authors: Billeret D. , Blondeau D. , Sliwa H. 
Published: March 2009

Abstract2‐Formyl‐3‐hydroxypyridine and its 6‐methyl derivative have been condensed with ethoxycarbonylmethyl‐enetriphenylphosphorane and alkyl derivatives to afford 5‐azacoumarins substituted in the second case by an alkyl group at 3‐position by two different ways according to the used phosphorane.
Studies on the chemistry of thieno‐anellated O,N‐ and S,N‐containing heterocycles. 2. Synthesis of thieno[2,3‐b]diazepine derivatives with potential CNS activity
Authors: Erker Thomas 
Published: March 2009

AbstractThieno‐anellated compounds analogous to Clobazam (1) [2] and the nootropic drugs 2 and 3 [3] were synthesized. Thus, nucleophilic substitution on halogenated nitrothiophene derivatives with aniline and reaction with ethyl malonyl chloride gave after cyclisation the thieno[2,3‐b]diazepinedione derivatives 7 and 14. These compounds were methylated to give the thieno‐anellated heterocycles 8 and 9.
The synthesis of a series of 7‐amino‐1‐cyclopropyl‐8‐fluoro‐1,4‐dihydro‐4‐oxo‐1,6‐naphthyridine‐3‐carboxylic acids as potential antibacterial agents
Authors: Sanchez Joseph P. , Gogliotti Rocco D. 
Published: March 2009

AbstractA series of 7‐amino‐1‐cyclopropyl‐1,4‐dihydro‐8‐fluoro‐4‐oxo‐1,6‐naphthyridine‐3‐carboxylic acids has been prepared and evaluated for antibacterial activity. These compounds were prepared by the displacement of the chloro substituent from 7‐chloro‐1‐cyclopropyl‐1,4‐dihydro‐8‐fluoro‐4‐oxo‐1,6‐naphthyridine‐3‐carboxylic acid employing the requisite nitrogen nucleophile to produce the title compounds. The naphthyridine acid was synthesized in ten steps from ethyl 2,4‐dihydroxy‐3‐nitro‐5‐pyridinecarboxylate. The key step in the sequence was a Schiemann reaction carried out using the hexafluorophosphate salt of the diazonium ion derived from ethyl 3‐amino‐2,4‐dichloro‐5‐pyridinecarboxylate.
Synthesis of cyclopentathiophenacetic acid derivatives. Reactivity of methyl 6‐oxo‐4,5‐dihydro‐6H‐cyclopenta[b]thiophen‐4‐acetate
Authors: Jilale Abderrahim , Netchitaïlo Pierre , Decroix Bernard , Vegh Daniel 
Published: March 2009

AbstractOxodihydrocyclopentathiophenacetic acids 4, 5 and 6 were synthesized from suitable 2‐ or 3‐formylthiophenes. Reactivity of the carbonyl group or the carboxylic group of these bicyclic systems was investigated. The Beckmann rearrangement of methyl 6‐oximino4,5‐dihydro‐6H‐cyclopenta[b]thiophen‐4‐acetate 12 is an interesting route to methyl 7‐oxo‐4,5,6,7‐tetrahydrothieno[2,3‐c]pyridin‐4‐acetate (13).
A facile method for 2‐thiophenacylidenethiazoline derivatives
Authors: Kim Sung Hoon , Kim Kyongtae , Kim Jaheon , Kim Kimoon , Kim Jung‐Hyup 
Published: March 2009

AbstractThe reactions of 2‐alkyl‐5‐phenylisothiazole‐3‐thiones with 2‐chloro‐1,3‐dicarbonyl compounds in chloroform gave the corresponding isothiazolium chlorides which, upon treatment at room temperature with sodium borohydride in a mixture of chloroform and ethanol, underwent SN bond cleavage to give 3‐alkyl‐4,5‐disubstituted‐2‐thiophenacylidenethiazolines. Similarly, treatment of the isothiazolium chlorides with triphenylphosphite in chloroform at 60° afforded the same thiazoline derivatives.
Research in the azole series. 103. Synthesis and 13C NMR study of pyrazole‐4‐carboxaldehydes
Authors: Echevarría Aurea , Elguero José , Meutermans Wim 
Published: March 2009

AbstractTen new pyrazoles have been prepared and their 13C nmr chemical shifts compared with those of twelve other pyrazoles, some of them prepared purposely for this study. The chemical shifts are discussed statistically assuming that they are additive. A formyl group in the position 4 of the pyrazole ring produces a large effect on carbon C4 (SCS = 17.3 ppm) and medium effects on carbons C3 (SCS = 1.9 ppm) and C5 (SCS = 3.8 ppm). The azines derived from pyrazole‐4‐carboxaldehydes are of the E,E‐configuration.
On triazoles XXX. Synthesis of [1,2,4]triazolo‐[1,5‐d][1,2,4,6]tetrazepine‐5‐thiones
Authors: Barkóczy József , Reiter József 
Published: March 2009

AbstractDifferent 2‐Q‐6,7,8,9‐(bi‐, tri‐ or tetra)substituted[1,2,4]triazolo[1,5‐d][1,2,4,6]tetrazepine‐5‐triione derivatives representing a novel ring system were synthesised. In the case of 8‐aryl‐substituted derivatives ring‐chain tautomerism was observed in DMSO‐d6 or deuteriochloroform solutions. In some cases both ring and chain tautomers could be isolated in crystalline form. The structure of products obtained was proved by nmr using also model compounds prepared for this purpose.
Acid‐catalyzed reaction of pyrazolo[1,5‐a]pyridines with aldehydes: Formation of bis(pyrazolo[1,5‐a]pyrid‐3‐yl)methane
Authors: Miki Yasuyoshi , Yagi Sanae , Hachiken Hiroko , Ikeda Masazumi 
Published: March 2009

AbstractReaction of pyrazolo[1,5‐a]pyridines with aldehydes in the presence of trifluoroacetic acid gave bis[pyrazolo[1,5‐a]pyrid‐3‐yl)methanes in high yields.
Ring chain transformations. XIV. 3‐(ω‐Aminoalkyl)‐1,2,4‐triazoles by reaction of isothiosemicarbazides with lactam acetals or lactim ethers
Authors: Radics Ute , Liebscher Jürgen 
Published: March 2009

AbstractIsothiosemicarbazide hydrohalides 1 react with lactam acetals 2 or lactim ethers 3 by the formation of lactamisothiosemicarbazones 4 or ring transformed 3‐(ω‐aminoalkyl)‐1,2,4‐triazoles 6. The latter can independently by synthesized by alkylation of lactamthiosemicarbazones 9. Condensation of primary 3‐(ω‐aminoalkyl)‐1,2,4‐triazoles 6 with lactim ethers 7 can lead to 3‐lactamiminoalkyl‐1,2,4‐triazoles 8.
Alkylation of quinazoline‐2,4(1H,3H)‐diones with 1,4‐dibromo‐2‐methylbut‐2‐ene under phase‐transfer‐catalysis
Authors: Reisch Johannes , Iding Marlies , Usifoh Cyril Odianose 
Published: March 2009

AbstractQuinazoline‐2,4(1H,3H)‐dione (1) was reacted with 1,4‐dibromo‐2‐methylbut‐2‐ene (2) to give two dialkylated products and two monoalkylated products. The reaction of 6,7‐dimethoxyquinazoline‐2,4(1H,3H)‐dione (8) with 1,4‐dibromo‐2‐methylbut‐2‐ene (2) resulted in the formation of three dialkylated products.
4H‐1‐benzothiopyran‐4‐one‐3‐carboxylic acids and 3,4‐dihydro‐2H‐isothiazolo[5,4‐bbenzothiopyran‐3,4‐diones as quinolone antibacterial analogs
Authors: Cecchetti Violetta , Fravolini Arnaldo , Fringuelli Renata , Schiaffella Fausto , Lorenzini Maria Cristina , Tabarrini Oriana 
Published: March 2009

AbstractThe endocyclic replacement of a nitrogen atom at the 1‐position of quinolone antibacterial nucleus with a sulfur atom was investigated. A series of 1‐benzothiopyran‐4‐one‐3‐carboxylic acids 14–16 and isothiazolo‐[5,4‐b][1]benzothiopyran‐3,4‐diones 22–24, suitably functionalized with a fluorine atom at C‐6 and heterocyclic base at C‐7, were prepared. The antibacterial evaluation of the target compounds showed an activity comparable to that of nalidixic acid for compounds 14–16, while an increased activity against gram‐positive bacteria was observed for compounds 22–24.
Reaction of enol type acyl cyanide with o‐aminophenol
Authors: Kurasawa Yoshihisa , Yoshishiba Noriko , Kureyama Tomomi , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa 
Published: March 2009

AbstractThe reaction of 7‐chloro‐4‐(2‐cyano‐2‐hydroxyvinyl)tetrazolo[1,5‐a]quinoxaline 2a with o‐aminophenol gave 7‐chloro‐4‐(b‐hydroxyphenylcarbamoylmethylene)4,5‐dihydrotetrazolo[1,5‐a]quinoxaline 4, while the reaction of compound 2a with o‐aminophenol hydrochloride afforded 4‐[2‐(2‐benzoxazolyl)‐2‐hydroxyvinyl]‐7‐chlorotetrazolo[1,5‐a]quinoxaline 5, whose acetylation provided 4‐[2‐acetoxy‐2‐(2‐benzoxazolyl)vinyl]‐7‐chlorotetrazolo[1,5‐a]quinoxaline 6. The behavior in a deuteriodimethyl sulfoxide or deuteriotrifluoroacetic acid solution is described for compounds 4–6.
Reaction of β‐keto ethyleneacetals with hydroxylamine: A correction
Authors: Paradkar Vidyadhar M. , Latham Tamara B. , Krishnaswami Ashok 
Published: March 2009

AbstractA reaction of 2‐(2‐nitrobenzoylmethyl)‐1,3‐dioxolane (3) with hydroxylamine, followed by acid catalyzed cyclization, produced 5‐(2‐nitrophenyl)isoxazole (5) as the only isolable product, whereas 2‐(benzoylmethyl)‐1,3‐dioxolane (9) under identical conditions produced a 2.5:1 mixture of 3‐phenyl and 5‐phenylisoxazoles 10 and 11. These findings contradict the literature report that β‐keto ethyleneacetals on treatment with hydroxylamine produce exclusively 3‐substituted isoxazoles. As an additional proof, 3‐(2‐nitrophenyl)isoxazole (8) was prepared by an unambiguous method via the nitrile oxide route for comparison. The intermediate obtained on treatment of 2‐(2‐nitrobenzoylmethyl)‐1,3‐dioxolane (3) with hydroxylamine was found to be an isomeric mixture of 5‐hydroxy‐5‐(2‐nitrophenyl)‐2‐isoxazoline (4) and the syn and anti mono‐oximes 19 (at least in solution), either of which could give 5‐(2‐nitrophenyl)isoxazole (5) on acid treatment. A mechanistic rationale is provided to explain the anomalous results.
Syntheses and photophysical properties of fluorescent 2‐aryl‐3‐hydroxy‐4‐chromenones
Authors: Kauffman Joel M. , Aziz Mohammed A. 
Published: March 2009

AbstractThe particle detectors proposed for the Super‐conducting Super Collider contain polystyrene scintillation fibers as a component. Scintillation fluors soluble in styrene are required which have improved light output and response time. New 2‐aryl‐3‐hydroxy‐4‐chromenones related to 3‐hydroxyflavone were prepared which displayed these improved properties. Improved solvent systems for chromenone formation were essential in the synthesis of two of the chromenones. One chromenone produced fluorescence emission at 560 nm with a quantum yield of 0.53 and a scintillation decay time of 5 nsec.
Reaction of 2,3‐dichloro‐5,6‐dicyanopyrazine with enamines and some tertiary amines
Authors: Hou Dongfeng , Oshida Atsushi , Matsuoka Masaru 
Published: March 2009

AbstractThe reaction of 2,3‐dichloro‐5,6‐dicyanopyrazine (1) with enamines as well as a few tertiary amines as enamine precursors was investigated. Both reactions gave aminovinyl‐substituted pyrazine derivatives. During the attempted purification of 3c or 3d by column chromatography on silica gel, 2‐chloro‐5,6‐dicyano‐3‐(1′‐oxocyclopent‐2′‐yl)pyrazine (4) was obtained, apparently by hydrolytic cleavage. The products prepared are all of interest as potential pesticides.
Heterocycles. 13. synthesis of [1,2‐d]triazolo steroids
Authors: Weintraub Philip M. 
Published: March 2009

AbstractReaction of 1,2‐epoxy‐5α‐3‐ketosteroids with sodium azide produces a mixture of expected 2‐azido‐5α‐δ1‐3‐ketosteroids and novel [1,2‐d]triazolosteroids. A possible pathway for formation of the latter involving 1,3‐dipolar cycloaddition of sodium azide is discussed.
Synthesis of novel 1‐aryl[1]benzoxepino[5,4‐c]pyrazole and [1]benzoxepino[5,4‐d]pyrimidine derivatives
Authors: Chetoni Fabio , Da Settimo Federico , La Motta Concettina , Primofiore Giampaolo 
Published: March 2009

AbstractSeveral 1‐aryl[1]benzoxepinopyrazoles were prepared by reaction of 4‐hydroxymethylene[1]benzoxepin‐ones with appropriate phenylhydrazine hydrochlorides. The direct condensation of hydroxymethylenebenz‐oxepinones with variously substituted amidines failed to give benzoxepinopyrimidines. These compounds were obtained via the key intermediates morpholine enaminobenzoxepinones.
An improved synthesis of cyclohexenothioxanthenones
Authors: Ran Ruicheng , Pittman Charles U. 
Published: March 2009

AbstractAn improved synthesis of cyclohexanothioxanthenones in high yield (70‐90%) by treatment of thiosalicylic acid (4) or 2,2′‐dithiosalicylic acid with 1,2,3,4‐tetrahydronaphthalene (5) in the presence of concentrated sulfuric acid or a mixture of 95% sulfuric acid with 27‐30% fuming sulfuric acid (in 5:1 to 2:1 v/v ratio) was described. The crude product consisted of three isomers which were isolated and identified. These isomers are 1,2‐, 2,3‐ and 3,4‐cyclohexanothioxantenone (1, 2, and 3).
Synthesis and nmr spectra of the six isomeric thieno[c]‐fused 1,7‐ and 1,8‐naphthyridines
Authors: Malm Johan , Rehn Bengt , Hörnfeldt Anna‐Britta , Gronowitz Salo 
Published: March 2009

AbstractThrough the use of Pd(0)‐catalyzed coupling between 2‐ and 4‐formyl‐3‐thiopheneboronic acid and 4‐iodo‐3‐aminopyridine (1) and 3‐bromo‐2‐aminopyridine, convenient one‐pot procedures for the preparation of thieno[2,3‐c]‐1,7‐naphthyridine (2), thieno[3,4‐c]‐1,7‐naphthyridine (3), thieno[2,3‐c]‐1,8‐naphthyridine (6) and thieno[3,4‐c]‐1,8‐naphthyridine (7) have been developed. Thieno[3,2‐c]‐1,7‐naphthyridine (4) and thieno[3,2‐c]‐1,8‐naphthyridine (8) were obtained through the coupling of 2‐tri‐n‐butylstannyl‐3‐thiophenaldehyde with 2,2‐dimethyl‐N‐(4‐iodo‐3‐pyridinyl)propanamide and 3‐bromo‐2‐acetamidopyridine (1). The yield of 8 was further increased when copper(II) oxide was used as the co‐reagent. The 13C nmr spectra of the six isomeric thieno[c]‐fused 1,7‐ and 1,6‐naphthyridines are discussed.
On the mechanism of the reduction of 1‐phenyl‐3‐(4‐pyridinylmethylene)‐2‐oxindole with sodium borohydride in methanol
Authors: Pierce Michael E. , Huhn George F. , Jensen James H. , Sigvardson Ken W. , Islam Qamrul , Xing Yide 
Published: March 2009

AbstractSodium borohydride reduction of 1‐phenyl‐3‐(4‐pyridinylmethylene)‐2‐oxindole1in methanol gives a high yield of the oxindole2, a precursor to linopirdine. The reduction is accelerated by methanol and the major by‐products during this reduction are the diastereomeric Michael adducts between1and2and the overreduced products,9and11. Surprisingly, indole9is not derived from further reduction of2but is formed concurrently, whereas the ring opened product11is the unexpected reduction product derived from2.
New [f]‐fused xanthines: Synthesis of 1,3‐dipropyl‐1H,3H‐pyrazino, pyrido, pyrimido and pyrrolo[2, 1‐f]purine‐2,4‐diones
Authors: Gatta Franco , Giudice Maria Rosaria Del , Borioni Anna , Mustazza Carlo 
Published: March 2009

AbstractSynthesis of 1,3‐dipropyl‐1H,3H‐pyrazino, pyrido, pyrimido and pyrrolo[2,1‐f]purine‐2,4‐diones, starting from 5,6‐diamino‐1,3‐dipropylpyrimidine‐2,4‐dione1and 6‐chloro‐1,3‐dipropylpyrimidine‐2,4‐dione14is described. A new synthetic approach to 1,3‐dipropyl‐1H,3H‐pyrido(or pyrazino)[1′,2′‐1,2]pyrimido[4,5‐d]pyrimidine‐2,4,5‐triones19 e, f, hhas been also developed.
Synthesis and characterization of ruthenium(ii) complexes of 5‐hydroxyflavones
Authors: Silva Artur M. S. , Cavaleiro José A. S. , Tarrago Georges , Marzin Claude 
Published: March 2009

AbstractBis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL2(DMSO)2, were synthesized by the reaction of dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) with the sodium salts of 5‐hydroxyflavone, 5‐hydroxy‐4′‐methoxyflavone and 5‐hydroxy‐3′,4′,5′,7‐tetramethoxyflavone, (L). The complexation was followed by 1H nmr spectroscopy. The 1:1 kinetically favoured tris(dimethyl sulfoxide)chloroflavonatoruthenium(II) complexes, RuLCl(DMSO)3, were initially formed and then transformed into the thermodynamically more stable ones. Each one of these complexes, by reacting with another equivalent of lig‐and L, also gave rise to a mixture of 1:2 kinetic species, from which the 1:2 thermodynamically more stable bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL2(DMSO)2, were formed. The complexes were characterized by extensive studies involving 1H, 13C nuclear magnetic resonance, infrared and ultraviolet‐visible spectroscopy, mass spectrometry, cyclic voltammetry and elemental analysis. Such 1:2 complexes exhibited properties of two nonequivalent flavonate ligands and also of two non‐equivalent dimethyl sulfoxide ligands; one of these dimethyl sulfoxide ligands is considered to be S‐bonded and the other O‐bonded. Also two quasireversible one‐electron redox steps were observed at 0.53 to 0.57 and 0.44 to 0.41 V (vs Saturated Calomel Electrode). The spectroscopic results obtained allow for the discussion of stereochemistry of each bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complex and to postulate its possible structure as one corresponding to the more anisochronous species.