bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on quinones. XII. Cycloketalization of michael adducts from hydroxyquinones
Authors: Cassis Raúl , Tapia Ricardo , Valderrama Jaime A. 
Published: April 2009

AbstractThe reaction of 2‐hydroxy‐3‐(1‐phenyl‐3‐oxobutyl)‐1,4‐naphthoquinone (1) with either acidic methanol or a mixture of trimethyl orthoformate, methanol and ammonium chloride resulted in the formation of the p‐quinonic cycloketals: trans‐ and cis‐4‐phenyl‐2‐methyl‐2‐methoxy‐3,4‐dihydro‐2H‐naphtho[2,3‐b]pyran‐5,10‐dione (2a,2b). Cyclization of the Michael adducts 6, 10 and 11, which are structurally related to 1, with trimethyl orthoformate‐methanol‐ammonium chloride gave the corresponding p‐quinonic cycloketals 7, 12 and 13. The structures of the regioisomers 2a and 2b are proposed based on the spectral properties of compound 7 and by analysis of its proton nmr spectra.
Reduction of the benzoyl group in substituted 5‐benzoyl‐4,5‐dihydro‐1,2,4‐oxadiazoles
Authors: Alcaide Benito , Escobar Gerardo , Pérez‐Ossorio Rafael , Plumet Joaquin 
Published: April 2009

AbstractThe carbonyl group of substituted 5‐benzoyl‐4,5‐dihydro‐1,2,4‐oxadiazoles can be reduced by lithium aluminium hydride at low temperature without ring opening. Mixtures of the two related diastereoisomeric benzylalcohols are obtained. Configurations were assigned by 1H‐nmr.
Facile preparation of symmetric bilirubins IIIα and XIIIα from IXα
Authors: Ma J.‐S. , Lightner D. A. 
Published: April 2009

AbstractImproved, simple precedures for synthesis and isolation of symmetrically substituted bilirubin‐XIIIα and bilirubin‐IIIα from the natural pigment, bilirubin‐IXα, are described.
Reactions of 3‐aminotropolone with acyl halides. Formation of 8H‐cyclohept[d]oxazol‐8‐ones
Authors: Imafuku Kimiaki , Furuya Miki , Jin Zhong‐Tian 
Published: April 2009

Abstract3‐Aminotropolone (1) reacted with acetyl chloride and propionyl chloride to give 2‐methyl‐ and 2‐ethyl‐8H‐cyclohept[d]oxazol‐8‐ones (2a and 2b), respectively. The reactions with benzoyl chloride and phenylacetyl chloride gave N‐acylated and N,O‐diacylated 3‐aminotropolones [(3a and 3b) and (4a and 4b)].
Mechanistic aspects of oxidation ofN‐substituted 5H‐dibenz[c,e]azepines by aldehyde oxidase
Authors: Thomas H. Greg , Ruenitz Peter C. 
Published: April 2009

Abstract5H‐Dibenz[c,e]azepine (2) and itsN‐ethyl andN‐(2‐ethoxyethyl) analogues3and4were prepared and evaluated as substrates for aldehyde oxidase. Quaternization of2with ethyl iodide furnished3, while4was prepared by lithium aluminum hydride reduction ofN‐(2‐ethoxy)ethyldiphenimide followed by mercuric acetate oxidation of the resultant amine6. The rates of oxidation of2and3were similar, suggesting a lack of selectivity by the enzyme for the respective imine and iminium functional groups in these compounds. The rate of oxidation of3decreased with increasingpH while the extent of “hydration” of this substrate increased over a similarpH range, signifying a preference by the enzyme for3over its carbinolamine equilibrium partner. Experiments with deuterium labelled analogues of2and3indicated that azomethine hydrogen loss from these substrates during enzymatic oxidation was not rate determining. Thus 5H‐dibenz[c,e]azepine‐5,5,7‐d3(7), prepared by lithium aluminum deuteride reduction of diphenimide (5), and itsN‐ethyl analogue8, had respective enzymatic oxidation rates which did not differ from those of their non‐deuterated counterparts.
The Thieno[2,3‐c]pyridine Reissert Compound
Authors: Bass R. J. , Popp F. D. , Kant J. 
Published: April 2009

AbstractThieno[2,3‐c]pyridine has been converted to 6‐benzoyl‐ and 6‐carbethoxy‐7‐cyano‐6,7‐dihydrothieno[2,3‐c]‐pyridine. Alkylation, condensation, Michael addition, and cyclo addition reactions of these Reissert type compounds have been carried out.
Synthesis of 5,6‐carbonyldioxyindole, a melanogenic cyclic carbonate ester of 5,6‐dihydroxyindole
Authors: Lutz Wilson B. , Mcnamara Craig R. , Olinger Max R. , Schmidt David F. , Doster Douglas E. , Fiedler Mark D. 
Published: April 2009

Abstract5,6‐Carbonyldioxyindole (4), a melanogenic derivative of 5,6‐dihydroxyindole (1), was synthesized by a procedure starting with 3,4‐methylenedioxycinnamic acid (5). Compound 4 is a stable crystalline solid which is readily hydrolyzed to 1, a key intermediate on the biosynthetic pathway from tyrosine to melanin.
Synthesis of 3‐[(aryl)‐1,2,4‐oxadiazol‐5‐yl]propionic acids
Authors: Srivastava Rajendra Mohan , Viana Maria Benedita De Assunl̂t́o Borges , Bieber Lothar 
Published: April 2009

AbstractSeven 3,5‐disubstituted oxadiazole derivatives, 3a‐g, have been prepared by direct condensation of appropriate benzamidoxime with succinic anhydride. Spectroscopic properties, especially uv, ir and mass spectra confirmed the cyclic 1,2,4‐oxadiazole structure. No ring‐opened intermediate or side product could be observed. The 1H‐nmr assignments of the two CH2 groups were unequivocally made by acid‐ and base‐induced shifts.
A novel rearrangement reaction. A single‐step conversion of tetrahydro‐1‐isoquinolinecarboxylic acids into 1‐isoquinolones
Authors: Vaccher Claude , Berthelot Pascal , Debaert Michel , Barbry Didier 
Published: April 2009

AbstractThe preparation of 2‐acyl‐6,7‐dimethoxy‐1,2,3,4‐tetrahydro‐1‐isoquinolinecarboxamides is described. The mixed anhydride of 2‐acyl‐6,7‐dimethoxy‐1,2,3,4‐tetrahydro‐1‐isoquinolinecarboxylic acid with isobutyl chloroformate was reacted with the corresponding hydrazines at — 10, — 15°. Besides those compounds, isoquinolones occur through a new side reaction. The structure of those products was established by13C and1H nmr and mass spectroscopy. A possible mechanism of the reaction is discussed.
Synthesis and antibacterial activity of 1‐(2,4‐dichlorobenzoyl)‐4‐substituted thiosemicarbazides, 1,2,4‐triazoles and their methyl derivatives
Authors: Goswami Birendra N. , Kataky Jiban C. Sarmah , Baruah Jogendra N. 
Published: April 2009

AbstractA series of 1‐(2,4‐dichlorobenzoyl)thiosemicarbazides, s‐triazoles and their methyl derivatives have been synthesised by condensation of 2,4‐dichlorobenzoyl hydrazine with aryl isothiocyanates. Subsequent ring closure of the substituted thiosemicarbazides yielded the s‐triazoles, and reaction with methyl iodide resulted methyl derivatives. All the compounds were subjected to in vitro testing against two gram‐positive and two gram‐negative bacteria. Antibacterial activity was found to be moderate to good in most of the compounds.
A novel synthesis of precursors to 3‐thienylmalonic acid
Authors: Raynolds Peter W. 
Published: April 2009

AbstractMethyl 2‐cyano‐2‐(3‐thienyl)acetate can be prepared in 95% yield by treating methyl 2‐cyano‐2‐(3‐tetra‐hydrothienylidene)acetate with sulfuryl chloride, followed by dehydrohalogenation with pyridine. The product can be hydrolyzed to 3‐thienylmalonic acid, a pharmaceutical intermediate.
Reaction of benzofurazan N‐Oxide with 1‐aza‐1,3‐butadienes. Synthesis of a novel class of quinoxaline N,N′‐dioxide imines
Authors: Devi Purabi , Sandhu Jagir S. 
Published: April 2009

Abstract1‐Aza‐1,3‐butadienes react with benzofurazan N‐oxide (BFO) to give a new class of N,N'‐dioxide imines.
2H‐[1]‐benzotellurinnone‐2 (telluro‐1 coumarine) et dihydro‐3,4‐chalcogéno‐1 coumarines
Authors: Christiaens Léon , Piette Jean‐Louis , Luxen André , Renson Marcel 
Published: April 2009

AbstractLa 2H[1]‐benzotellurinnone‐2 (telluro‐1 coumarine), et des dihydro‐3,4‐ chalcogéno‐1 coumarines ont été synthétisées par cyclisation intramoléculaire de l'acide ou du chlorure d'acide correspondant. Les nouveaux systèmes hétérocycliques sont caractérisés par différentes méthodes physicochimiques: ir, rmn 1H et 13C et spectrométrie de masse.
Halogenated ketenes. 39. A new synthesis for substituted coumarins
Authors: Brady William T. , Shieh C. H. 
Published: April 2009

AbstractA new general synthesis of substituted coumarins is described. The in situ cycloaddition of chloroketenes with α‐methoxymethylenecyclohexanones yields (4 + 2) cycloaddition products, 3,4‐dihydro‐2‐pyranones. The chlorine atom is reductively removed and methanol is spontaneously eliminated to yield the 5,6,7,8‐tetra‐hydrocoumarins. Dehydrogenation of these compounds results in good yields of the substituted coumarins.
Zur addition von nucleophilen an C(2) heterocyclischer 2‐methylsubstituierter quartärsalze
Authors: Schelz Dieter 
Published: April 2009

Abstract1‐(4‐Chlorophenyl)‐2‐methyl‐3‐phenylquinoxalinium perchlorate (5) obtained by two different routes, on treating with nucleophiles HX or X− yielded 1,3‐diaryl‐2‐methyl‐2X‐1,2‐dihydroquinoxalines 10. Alkylation of 10e yielded 4‐(4‐chlorophenyl)‐1,3‐dimethyl‐3‐nitromethyl‐2‐phenyl‐3,4‐dihydroquinoxalinium perchlorate (11e). The 1H‐nmr and mass spectra are presented. Diastereoisomerism of the products is discussed.
New route to N‐aryl and N‐heteroaryl derivatives of 4‐hydroxy‐3‐quinolinecarboxamides
Authors: Clémence François , Le Martret Odile , Collard Jeannine 
Published: April 2009

AbstractThe synthesis of N‐aryl and N‐heteroaryl substituted 4‐hydroxy‐3‐quinolinecarboxamides 1 is described. The attack of dianions 12 of N‐aryl substituted acetamides on the C‐4 carbonyl of 4H‐3,1‐benzoxazin‐4‐ones 11 gave rise to ketoamides 13, which smoothly cyclised in the presence of bases to afford quinolinecarboxamides 1. By this method, a large number of 2‐substituted 4‐hydroxyquinolinecarboxamides can be prepared.
Stereochemical studies. 81. Saturated heterocycles. 69. Preparation of methylene‐bridged 3,1‐benzoxazines, 3,1‐benzoxazin‐2‐ones and 3,1‐benzoxazine‐2‐thiones
Authors: Stájer Géza , Szabó Angela E. , Fülöp Ferenc , Bernáth Gábor , Sohár Pál 
Published: April 2009

Abstract3‐exo‐Aminobicyclo[2.2.1]hept‐5‐ene‐2‐exo‐carboxylic acid and ethyl 3‐endo‐aminobicyclo[2.2.1]heptane‐2‐endo‐carboxylate (6) were reduced with lithium aluminum hydride to the corresponding bicyclic aminoalcohols 3 and 4. These and the saturated endo‐endo and exo‐exo N‐methylaminoalcohols 16 and 22, respectively, were converted to methylene‐bridged tetrahydro‐ (11) and hexahydro‐3,1‐benzoxazin‐2‐ones 12, 17, 23 and 3,1‐benzoxazin‐2‐thiones 13, 14, 18, 24. The exo‐exo 3 and endo‐endo 4 aminoalcohols were cyclized by means of ethyl arylimidates to tricyclic dihydro‐1,3‐oxazines 7a‐d, 8a‐d. The structures were confirmed by ir, 1H and 13C nmr spectroscopy.
Addition des azidosulfates sur le norbornadiène
Authors: Hedayatullah Mir , Hugueny Jean Claude , Guy Alain 
Published: April 2009

AbstractL'action des azidosulfates d'aryle sur le norbornadiène fournit sélectivement et avec de hauts rendements, les N‐(aroxysulfonyl) aza‐2 bicyclo[3,2,1]octadiènes‐3,6 résultant de l'insertion de l'azote dans le cycle. La structure des nouveaux produits d'expansion du cycle ainsi formés a été établie par dégradation hydrolytique, synthèse indépendante et données spectrales (ir, rmn).
Reactions and rearrangement of 2,4‐quinazolinediones. An efficient simple synthesis of 3‐amino‐1H,3H‐quinazolinedione
Authors: Badawy M. A. , Ibrahim Yehia A. , Kadry Azza M. 
Published: April 2009

AbstractAn efficient synthesis of 3‐amino‐1H,3H‐quinazolinedione by the action of hydrazine on the readily accessible 3‐phenyl‐2,4(1H,3H)‐quinazolinedione and 2‐anilino‐4H‐3,1‐benzoxazin‐4‐one are described.
Le polyphosphate d'éthyle, un réactif de choix pour la synthèse de dérivés du benzo[b]furanne dicarboxylate‐2,3 de méthyle
Authors: Belleney Joël , Vebrel Joël , Cerutti Ernest 
Published: April 2009

AbstractCe travail a pour objectif la mise au point d'une méthode rapide et efficace de synthèse de dérivés méthylés du benzo[b]furanne dicarboxylate‐2,3 de méthyle. Nous apportons pour cela des améliorations significatives à la méthode de Koelsch et Whitney [1], notamment grǎce à l'emploi du polyphosphate d'éthyle. Ce réactif se révèle en effet particulièrement bien adapté à la cyclodéshydratation des aryloxy‐2 hydroxy‐3 maléates de méthyle intermédiaires en dérivés benzofuranniques, puisque les rendements dépassent le plus souvent 80%.
Pyrimidines. 21. Novel reactions of 5‐cyano‐1,3‐dimethyluracil with carbon nucleophiles. A facile preparation of certain pyrido[2,3‐d]pyrimidines
Authors: Su Tsann‐Long , Watanabe Kyoichi A. 
Published: April 2009

AbstractTreatment of 5‐cyano‐1,3‐dimethyluracil (8) with an activated acetonitrile, such as malononitrile, ethyl cyanoacetate or cyanoacetamide, in base afforded 7‐amino‐6‐cyano‐, 7‐amino‐6‐ethoxycarbonyl‐, and 7‐amino‐6‐aminocarbonyl‐1,3‐dimethylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione (18b, 18c and 18d, respectively) in high yields. On the other hand, reaction of 8 with acetonitrile in base gave the Michael adduct, 5‐cyano‐6‐cyanomethyl‐5,6‐dihydrouracil (15, R = H), and the hydrated product, 1,3‐dimethyluracil‐5‐carboxamide (9) as the major products, and 7‐amino‐1,3‐dimethylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione (18a) in only very low yield. Similar reaction with butanone gave 7‐ethyl‐1,3‐dimethyl‐ and 1,3,6,7‐tetramethylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione (10b and 10c) in low yields.When 8 was treated with diethylmalonate in base, only a small amount of 6‐ethoxycarbonyl‐1,3‐dimethylpyrido[2,3‐d]pyrimidine‐2,4,7(1H,3H,8H)‐trione (19) was obtained together with 1,3‐dimethylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione (20) and 18c (also in low yields). Treatment of 8 in ethanolic sodium ethoxide without added carbon nucleophile gave significant amounts (14%) of 20 and a small amount of 18c.
Synthesis of 1H‐pyrazolo[3,4‐e]‐s‐triazolo[3,4‐c]‐as‐triazines, 8H‐pyrazolo[3,4‐e]tetrazolo[5,1‐c]‐as‐triazine and 1,7‐dihydro‐8H‐pyrazolo[3,4‐e]‐as‐triazine derivatives
Authors: Youssef M. S. K. , Hassan Kh. M. , Atta F. M. , Abbady M. S. 
Published: April 2009

Abstract3‐Hydrazino‐7‐methyl‐5‐phenyl‐5H‐pyrazolo[3,4‐c]‐as‐triazine 1 underwent ring closure and/or condensation reaction with formic acid, acetic acid, acetic anhydride and benzoyl chloride to afford 1H‐pyrazolo‐[3,4‐d]‐s‐triazolo[3,4‐c]‐as‐triazines 2, 5 and 7a and/or N‐acyl derivatives 3, 4 and 6. N‐Acyl derivatives 3 and 6 underwent cyclisation reaction on treatment with phosphoryl chloride to give 5 and 7a. 3‐Methyl‐1‐phenyl‐8‐aryl‐1H‐pyrazolo[3,4‐e]‐s‐triazolo[34,‐c]‐as‐triazines 7 were also prepared by the reaction of the hydrazono derivatives 8 wit thionyl chloride. On treatment of 1 with nitrous acid gave the 8H‐pyrazolo[3,4‐e]tetrazolo‐[5,1‐c]‐as‐triazine 9. Compound 1 underwent ring closure with carbon disulphide or ethyl chloroformate to 1,7‐dihydro‐8H‐pyrazolo[3,4‐e]‐s‐triazolo[3,4‐c]‐as‐triazine derivatives 10 and 12. Reaction of 1 with ethyl acetoacetate or acetylacetone gave 3‐pyrazolo derivatives 13 and 14.
Synthesis of bridgehead nitrogen heterocycles from pyrylium salts and β‐functionalized amines
Authors: Molina P. , Alajarin M. , Lorenzo‐Peña M. , Tárraga A. , Vilaplana M. J. 
Published: April 2009

Abstractβ‐Functionalized primary amines are converted by the 2‐ethoxycarbonyl‐4,6‐diphenylpyrylium cation into the corresponding bicyclic salts 2. The N‐substituted 4,6‐diphenylpyridine‐2‐thiones 6 undergo cyclization to the byciclic compounds 8 by action of methyl iodide.
The reaction of 2‐(3‐sydnonyl)phenylmethanol with sulfonyl chlorides. A one pot conversion to the chloro congener
Authors: Turnbull Kenneth 
Published: April 2009

AbstractThe interesting transformation of 2‐(3‐sydnonylphenylmethanol (1) to its chloro congener 2, in moderate to good yield using sulfonyl chlorides, is described. A mechanism for the transformation is suggested.
Novel 2′‐substituted amino‐3‐methoxy‐16α‐bromo‐17‐oxoestra‐3,5(10)‐dieno[1,2‐b]thiazoles
Authors: Omar A.‐Mohsen M. E. , Aboulwafa Omaima M. 
Published: April 2009

AbstractA novel series of steroidal[1,2‐b]thiazoles was synthesized by cyclization of several thiourea derivatives with bromine according to Hugerschoff synthesis. The H‐nmr spectral analyses elucidating the structure of the products and the orientation of ring closure are reported.
Synthesis of 6‐halogenated 4H‐1,4‐benzothiazines
Authors: Gupta R. R. , Kumar Rakesh , Gautam R. K. 
Published: April 2009

AbstractThe synthesis of 6‐halogenated 4H‐1,4‐benzothiazines is reported by the condensation and oxidative cyclization of 4‐substituted 2‐aminobenzenethiols (I, R = Cl, Br) with β‐diketones in presence of DMSO. The ir, nmr and mass spectral studies are included. 4‐Substituted 2‐aminobenzenethiols were also prepared by an improved and direct method.
Synthesis and determination of maximum rotatory power of (+)‐(S)‐5‐s‐butyl‐2(1H)‐pyridinone
Authors: Chelucci G. , Marchetti M. , Soccolini F. , Botteghi C. 
Published: April 2009

AbstractOptically active (S)‐5‐s‐butyl‐2(1H)‐pyridinone (6) is obtained by reaction of 2‐s‐butylacrolein (1) and N‐(carbamylmethyl)pyridinium chloride. The relationship between optical activity and minimum optical purity is determined.
Stereoselective addition of carbamates to unsaturated systems by means of mercury(II) nitrate. Synthesis of saturated nitrogen‐containing heterocycles
Authors: Barluenga J. , Jiménez C. , Nájera C. , Yus M. 
Published: April 2009

AbstractThe aminomercuration of dienes with carbamates and mercury(II) nitrate affords, after in situ demercuration with sodium borohydride, stereoselectively saturated nitrogen‐containing heterocycles. Thus, the corresponding amidomercuration‐demercuration of 1,4‐ or 1,5‐hexadiene, and diallyl ether gives respectively N‐alkoxycarbonyl cis‐2,5‐dimethylpyrrolidines and trans‐3,5‐dimethylmorpholines. From 1,5‐cyclooctadiene 9‐alkoxycarbonyl‐9‐azabicyclo[3.3.1]‐ and [4.2.1]‐nonanes (molar ratio ca. 1:1) are obtained. By amidomercuration‐demercuration of N‐allylurethane cis‐N,N'‐bis(ethoxycarbonyl)‐2,5‐dimethylpiperazine is obtained. The intermolecular amidomercuration of unsaturated systems results stereochemically opposite to the same aminomercuration process.
Reactions of ethyl β‐methoxycrotonate with some α,β‐unsaturated carbonyl compounds. Synthesis of 6‐aroyl‐5‐aryl‐3‐methoxycyclohex‐2‐enones
Authors: Shandala Mowafak Y. , Ayoub Mikdad T. , Kareem Ahmad A. 
Published: April 2009

Abstract3‐Aryl‐1‐phenyl‐2‐propen‐1‐ones Ia‐h and 1‐aryl‐3‐phenyl‐2‐propen‐1‐ones Ii‐ℓreacted with ethyl β‐methoxy‐crotonate (II) in the presence of sodium hydride in dry THF at 0° for 10 hours to give the corresponding 6‐aroyl‐5‐aryl‐3‐methoxy‐2‐cyclohexen‐1‐ones III. The structures of the products were confirmed by ir, pmr, 13C nmr and uv spectroscopy.
Synthesis of the monomethyl isomers of naphtho[1′,2′:4,5]thieno[2,3‐c]quinoline
Authors: Kudo Hirotaka , Castle Raymond N. , Lee Milton L. 
Published: April 2009

AbstractThe synthesis of naphtho[1′,2′:4,5]thieno[2,3‐c]quinoline (11) and four monomethyl isomers is described.
The structural effects of fluorine substitution in pyridine, pyrimidine, and s‐triazine: An ab initio study
Authors: Boggs James E. , Pang Frank 
Published: April 2009

AbstractThe structures of 2‐fluoropyridine, 3‐fluoropyridine, 4‐fluoropyridine, pentafluoropyridine, 2‐fluoropyrimidine, 5‐fluoropyrimidine, and fluoro‐s‐triazine have been evaluated by the ab initio gradient method with a 4‐21 basis set augmented as needed with polarization functions on nitrogen. The structural effects of fluorination on the parent heterocycle are very similar to the effects of fluorination on benzene studied earlier. The ring angle is enlarged by about 2° at the point of fluorination and the adjacent ring bonds are shortened, much more for an adjacent C‐N than for C‐C. Fluorination of pyridine at the C2 position causes an in‐crease of bond localization in the ring. Rotational constants calculated from the structural parameters corrected with standard offset values are in exceptionally close agreement with experimental constants where these are known.
The synthesis of phenanthrodibenzothiophenes
Authors: Kudo Hirotaka , Tedjamulia Marvin L. , Castle Raymond N. , Lee Milton L. 
Published: April 2009

AbstractThe synthesis of phenanthro[1,2‐c]dibenzothiophene (6), phenanthro[4,3‐c]dibenzothiophene (10), phenanthro[2,1‐a]dibenzothiophene (14), phenanthro[3,4‐a]dibenzothiophene (16), phenanthro[1,2‐a]dibenzothiophene (19), phenanthro[2,1‐b]dibenzothiophene (20), 8‐methylphenanthro[3,2‐a]dibenzothiophene (24), 7‐methylphenanthro[1,2‐a]dibenzothiophene (25), phenanthro[3,4‐a]dibenzothiophene (27), phenanthro[4,3‐a]‐dibenzothiophene (28), 6‐methylphenanthro[2,3‐a]dibenzothiophene (31), and 5‐methylphenanthro[4,3‐a]dibenzothiophene (32) is described.
A simple oxidation of formycin to oxoformycin and oxoformycin B. Synthesis of 6‐methyloxoformycin, AC‐nucleoside analog of doridosine
Authors: Ugarkar Bheemarao G. , Revankar Ganapathi R. , Robins Roland K. 
Published: April 2009

AbstractA simple, high‐yield procedure has now been developed for the direct oxidation of formycin to oxoformycin and oxoformycin B. Treatment of formycin(1)with bromine/water provided oxoformycin(8). A similar treatment of formycin B(4)gave oxoformycin B(6). Upon prolonged exposure of either1or8to bromine/water at reflux temperature, conversion to6occurred in good yield. Application of this procedure to 1‐methylformycin(2), 1‐methylformycin B(5)and 2‐methylformycin(17)gave 1‐methyloxoformycin(9), 1‐methyloxoformycin B(7)and 2‐methyloxoformycin(18), respectively. Deamination of8and9with nitrosyl chloride also gave6and7, respectively. This selective oxidation of 6‐methylformycin gave 7‐amino‐6‐methyl‐3‐β‐D‐ribofuranosylpyrazolo[4,3‐d]pyrimidin‐5(4H)‐one(10), aC‐nucleoside analog of doridosine. A similar oxidation of 1,6‐dimethylformycin B(11)gave 1,6‐dimethyloxoformycin B(12). This direct introduction of the 5‐oxo function into the pyrazolo[4,3‐d]pyrimidine ring appears to be due to the attack of Br+at N(4), followed by the addition of water to C(5) and subsequent elimination of hydrogen bromide from the transient intermediate3.
Research on nitrogen heterocyclic compounds. XV. Synthesis of 1H,4H‐pyrazolo[4,3f]pyrrolo[1,2‐a][1,4]diazepine derivatives
Authors: Massa Silvio , Stefancich Giorgio , Artico Marino , Corelli Federico 
Published: April 2009

AbstractThe synthesis of derivatives of 1H,4H‐pyrazolo[4,3‐f]pyrrolo[1,2‐a][1,4]diazepine, a new tricyclic nitrogen‐containing nucleus is reported. Condensation of arylaldehydes with 4‐aminomethyl‐1‐phenyl‐5‐(1‐pyrryl)pyrazole afforded the title compounds. Bischler‐Napieralski intramolecular cyclization of 4‐acetamidomethyl‐1‐phenyl‐5‐(1‐pyrryl)pyrazole was also studied. The reaction led to 6‐methyl‐1‐phenyl‐1H,4H‐pyrazolo[4,3‐f]pyrrolo[1,2‐a][1,4]diazepine or alternatively to 4‐chloromethyl‐1‐phenyl‐5‐(1‐pyrryl)pyrazole depending on the solvent used.
A new mesoionic thia‐sydnone‐arylimine system. Synthesis and molecular structure
Authors: Kozinskij V. A. , Zelenskaja O. V. , Brückner S. , Malpezzi L. 
Published: April 2009

AbstractMethylation of 5‐phenylamino‐1,2,3‐thiadiazole led regiospecifically to mesoionic 3‐methyl‐5‐phenylimino‐1,2,3‐thiadiazole, its molecular structure was determined by X‐ray diffraction analysis. 3‐Aryl‐5‐arylimino‐1,2,3‐thiadiazoles were obtained by replacement of chlorine in 3‐aryl‐4,5‐dichloro‐1,2,3‐thiadiazolium perchlorates with excess arylamine.