bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rearrangement reactions of heterocycles. 12. Rearrangement of 6‐substituted pyrido[1,2‐a]pyrimidines to isomeric 1,8‐naphthyridines and some of their further reactions
Authors: Schober Bernt D. , Kappe Thomas 
Published: April 2009

Abstract2‐Amino‐6‐methylpyridine (4) reacts with active malonates 2a‐d or 3a‐d either in acetone solution with triethylamine as catalyst at room temperature or with active malonates 2a‐d in acetone solution at reflux temperature to yield the pyrido[1,2‐a]pyrimidines 5a‐d. 2,6‐Diaminopyridine (8) already reacts without triethylamine with 2a‐d at room temperature to afford the pyrido[1,2‐a]pyrimidines 9a‐d. At higher temperatures pyrido[1,2‐a]pyrimidines 5 and 9 are rearranged via ketene intermediates [1] to yield the 1,8‐naphthyridines 6a‐d, and 10a‐d, respectively. The naphthyridines 6 and 10 can also be synthesized directly from 4 or 8 using either diethyl malonates 1 or — with better results — the active malonates 2 at 240–250°. Further reaction of 10a‐e with 2c,d leads to the pyridonaphthyridines 12a‐f. Nitration of 6c yields the nitro derivative 16 and chlorination of 6c,d gives 15c,d, while the chlorination of 10c affords the di‐chloro derivative 17.
Photochemistry of ommochrome pigments
Authors: Bolognese Adele , Liberatore Rosa 
Published: April 2009

AbstractThe ommochrome pigment present in the eyes of Loligo Vulgaris was extracted with a butanol‐acetic acid‐hydrochloric acid solution. The extraction mixture was examined before and after irradiation by visible light. A phenoxazinone ring opening together with a photo‐induced solvent addition, causing a yellow‐red batho‐chromic shift, were observed and a plausible explanation of the process has been carried out and is reported on the basis of the isolated products.
Oxidation of 3‐hydroxykynurenine. A reexamination
Authors: Bolognese A. , Liberatore R. , Riente G. , Scherillo G. 
Published: April 2009

AbstractThe oxidation mixture of 3‐hydroxykynurenine (1), treated with aqueous acetic anhydride and, subsequently, with acidic methanol, yields the 1‐hydroxy‐3‐carbomethoxy‐5‐methoxy‐11‐(β‐aspartoyl‐N‐acetyl‐methyl ester)pyrido[3,2‐a]phenoxazine (5), the 1‐hydroxy‐11‐(β‐aspartoyl‐N‐acetyl‐methyl ester)‐5.H‐pyrido[3,2‐a]‐phenoxazin‐5‐one (6), the 1‐methoxy‐11‐(β‐aspartoyl‐N‐acetyl‐methyl ester)‐5H‐pyrido[3,2‐a]phenoxazin‐5‐one (6a), the l,5‐dimethoxy‐11‐(β‐aspartoyl‐N‐acetyl‐methyl ester)pyrido[3,2‐a]phenoxazine (7) and the 1‐methyl‐1(1′‐[11‐(β‐aspartoyl‐methyl esterimino)]ethenyl)ketal‐1H,5H‐pyrido[3,2‐a]phenoxazin‐5‐one (8). A probable scheme, for the compound formation, is reported.
Synthesis of substituted benzo[b]thiophenes by acid‐catalyzed cyclization of thiophenylacetals and ketones
Authors: Pié Patrick A. , Marnett Lawrence J. 
Published: April 2009

AbstractBenzo[b]thiophenes substituted at the 3 position with methyl or carboxymethyl and at the 5 position with methyl, methoxy, chloro, bromo and nitro were prepared by cyclization of thiophenyl‐acetals and ketones using a suspension of polyphosphoric acid in refluxing chlorobenzene. The overall efficiency of this method is superior to literature procedures because of the lower temperature and the limited amount of PPA used.
Synthesis of 3‐bromo and 3‐methoxy‐5‐isoxazolylglycine derivatives. Hypothetic precursors of ibotenic acid
Authors: Chiarino Dario , Napoletano Mauro , Sala Alberto 
Published: April 2009

AbstractA simple synthesis of 3‐bromo and 3‐methoxy analogues of ibotenic acid is reported starting from the corresponding 2‐(3‐substituted‐5‐isoxazolyl)‐2‐oxoacetic acid esters.
Color and constitution. Part 8. Some novel dyestuffs containing indoxyl residues
Authors: Katritzky Alan R. , Li Qiao‐Ling , Fan Wei‐Qiang 
Published: April 2009

AbstractNovel dyes containing C‐likned indoxyl residues are prepared by two routes: (a) by the reaction of C‐electrophiles with N‐acetylindoxyl and (b) by the reaction of active methylene compounds with 2‐chloroindole‐3‐one. The visible absorption spectra are recorded and discussed.
A novel regioselective t‐butylation as applied to the synthesis of 5‐cyano‐1‐(1,1‐dimethylethyl)‐N‐methyl‐1H‐pyrazole‐4‐carboxamide
Authors: Tao E. V. P. , Aikins J. , Rizzo J. , Beck J. R. , Lynch M. P. 
Published: April 2009

AbstractThe title compound was synthesized in a regiocontrolled way from 5‐cyano‐1H‐pyrazole‐4‐carboxylic acid, ethyl ester (5) with isobutylene, p‐toluenesulfonic acid and methylamine.
Crystal structure, dissociation and zwitterion formation in 2,6‐diaryl‐1(3)‐oxo‐3(1)‐hydroxy‐5(7)‐imino‐7(5)‐amino‐1 H,5H‐(3‐H,7H)‐pyrazolo[1,2‐a]pyrazoles
Authors: Zvilichovsky Gury 
Published: April 2009

AbstractSingle crystal X‐ray analysis and quaternization of 2,6‐diphenyl‐1(3)‐oxo‐3(1)‐hydroxy‐5(7)‐imino‐7(5)‐1H,‐5H[3H,7H)‐pyrazolo[1,2‐a]pyrazole is described. The dissociation constants are determined and compared with those of 4‐phenyl‐1,2‐dimethyl‐3(5)‐oxo‐5(3)‐hydroxypyrazole and 4‐phenyl‐3,5‐diaminopyrazole. The quaternization of the latter compound is also described. The influence of electron donating substituents at the cationic moiety on the electronic spectra of such paraionic systems is discussed. The title products exist in the solid state as zwitterions and probably as covalent species in solution.
Acidity and alkylation of 4‐phenyl‐3,5‐dihydroxypyrazole and its derivatives. C versus O and N alkylation
Authors: Zvilichovsky Gury , David Mordechai 
Published: April 2009

Abstract4‐Phenyl‐3,5‐dihydroxypyrazole is a relatively strong acid, with a pKa of 3.70. The effect of substitution, both in the phenyl ring and on the heterocyclic ring, on the acidity was studied. Electron attracting groups on the phenyl group enhance the acidity. Selective replacement by an alkyl group of one or two of the heterocyclic hydrogens lowers the acidity. Meerwein reagent, as well as methyl iodide bring about alkylation on carbon, whereas diazomethane and diethyl sulfate do not. Michael addition proceeds through both carbon and nitrogen.
Bridged cyanine dyes. Part 3. Zwitterionic bis‐4‐pyridyl and cationic bis‐dimethylanilino derivatives
Authors: Katritzky Alan R. , Fan Wei‐Qiang , Jiao Xue‐Shun , Li Qiao‐Ling 
Published: April 2009

AbstractThe preparation is described of two novel classes of bridged cyanines: zwitterionic bis‐4‐pyridyl and cationic bis‐dimethylanilino and bis‐methylcarbazolyl derivatives 5 and 11. In these compounds an uneven number of carbon atoms of the methine chain forms part of a five‐ or six‐membered ring. The visible absorption is discussed.
Synthesis and biodistribution of p‐iodophenyl analogues of a naturally occurring imidazole ribonucleoside
Authors: Suggs Jennifer A. , Srivastava Prem C. 
Published: April 2009

AbstractA model iodophenyl imidazole ribonucleoside has been synthesized to study biodistribution properties in laboratory animals. The key intermediate 5‐amino‐1‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)imidazole‐4‐[N‐(p‐iodophenyl)carboxamide] (5) was synthesized by coupling N‐succinimidyl‐5‐amino‐1‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)imidazole‐4‐carboxylate (4) and p‐iodoaniline. Deacetylation of the intermediate compound gave 5‐amino‐1‐β‐D‐ribofuranosylimidazole‐4‐[N‐(p‐iodophenyl)]carboxamide (6). Ring annulation via diazotization of 5 gave 7‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)imidazo[4,5‐d]‐v‐triazin‐[3‐N‐(p‐iodophenyl)]‐4‐one (7). Subsequent deacetylation of 7 afforded 7‐β‐D‐ribofuranosylimidazo[4,5‐d]‐v‐triazin‐[3‐N‐(p‐iodophenyl)]‐4‐one (8). The radiolabeled compounds, [125I]5 and [125I]6 were prepared in a manner similar to the corresponding unlabeled compounds except that p‐[125I]iodoaniline was used for coupling with 4. Biodistribution studies of iodine‐125‐labeled 5 and 6 were performed in female Fischer rats and tumor bearing nude mice. Compound 6 showed uptake in the brain and proliferating tissues such as tumor and bone‐marrow.
Ring‐opening reaction of 1,3,4‐oxadiazolone and 1,3,4‐oxadiazolinethione: Reaction of 2‐phenyl‐1,3,4‐oxadiazolin‐5‐one and 2‐phenyl‐1,3,4‐oxadiazoline‐5‐thione with amines
Authors: Saegusa Yasuo , Harada Shigeo , Nakamura Shigeo 
Published: April 2009

AbstractThe ring‐opening abilities of amines toward 1,3,4‐oxadiazolines, 2‐phenyl‐1,3,4‐oxadiazolin‐5‐one (1a) and 2‐phenyl‐1,3,4‐oxadiazoline‐5‐thione (1b), were investigated with relation to their basicities or pKb values. Oxadiazolines 1a and 1b were easily reacted with amines such as benzylamine and aniline, but not with p‐nitroaniline, to form the corresponding ring‐opening adducts. The reactions of both 1a and 1b with o‐phenylenediamine produced benzodiazoles with the liberation of benzoylhydrazide, whereas the reactions with o‐aminobenzamide furnished quinazolines with the liberation of ammonia. o‐Aminophenol and o‐aminothiophenol were also reacted with 1a and 1b both of them giving 1,5‐dibenzoylcarbohydrazide from 1a and 1,2‐dibenzoylhydrazine from 1b. From the conditions affording the corresponding ring‐opening adducts or reaction products, the ring‐opening abilities of the amines toward 1a and 1b are in good correlation with the strength of their basicities or pKb values. The ring‐opening of oxadiazolines were proved to occur with anilines. Therefore, the other reactions are also supposed to proceed via the ring‐opening steps.
The study of atropoisomers of meso‐tetrakis[2.2]paracyclophanylporphyrin
Authors: Czuchajowski Leszek , Goszczynski Stefan , Wisor Antoni K. 
Published: April 2009

AbstractTheoretical considerations of atropoisomers of the title compound have revealed the existence of a large number of stable isomeric species. Syntheses, carried out according to two procedures at widely separated temperatures, resulted in the formation of mixtures of atropoisomers in good yield. Two isomeric fractions have been separated and characterized. Some analytical methods have been worked out and have proved useful in separational techniques.
Synthesis of new [[(3‐substituted‐5‐isoxazolyl)‐alkyliden]iminooxy]aminopropanol derivatives
Authors: Chiarino D. , Ferrario F. , Napoletano M. , Sala A. 
Published: April 2009

AbstractThe preparation of new [[(3‐substituted‐5‐isoxazolyl)alkyliden]iminooxy]aminopropanol compounds is reported starting from the corresponding 1‐isoxazolylalkanones. The 1H‐ and 13C‐nmr studies, carried out to establish the Z‐ and E‐configuration of new derivatives, are also described.
Tricyclic heterocyclic systems: Pyrazolo[5′,4′:4,5]‐and pyrazolo‐[3′,4′:4,5]pyrano[2,3‐b]pyridine derivatives
Authors: Melani Fabrizio , Cecchi Lucia , Colotta Vittoria , Palazzino Giovanna , Filacchioni Guido 
Published: April 2009

AbstractBy reacting 2‐chloronicotinoyl chloride with acetyl or benzoyl acetate, ethyl 2‐methyl‐ or 2‐phenyl‐4‐oxopyrano[2,3‐b]pyridine‐3‐carboxylates were prepared. The nucleophilic rearrangement of the latter with hydrazines gave rise to the title compounds.
Derivatives of 2‐oxo‐3(2H)‐benzothiazolineacetonitrile and related compounds. I. Synthesis of N‐hydroxy‐2‐oxo or thioxo‐3(2H)‐benzothiazolineethanimidamide and related products
Authors: D'Amico John J. , Marvel John T. , Bollinger Frederic G. 
Published: April 2009

AbstractThe following methods afforded the titled acetonitriles 1–5 in excellent yields: (1) the reaction of the appropriate 2‐benzothiazolinones with chloroacetonitrile under basic conditions and (2) the dehydration of the appropriate 2‐oxo‐3(2H)‐benzothiazolineacetamides with phosphorus oxychloride or pentoxide. The reaction of the acetonitriles 1–5 and 2‐thioxo‐3(2H)‐benzothiazolmeacetonitrile with hydroxylamine afforded the titled compounds 6–11. Supporting nmr and mass spectral data are discussed.
Some reactions of 1‐alkyl‐1,2,3,4‐tetrahydropyridines with organic azides. Synthesis of 1‐alkylpiperidylidene‐2‐sulfonamides
Authors: Warren Brent K. , Knaus Edward E. 
Published: April 2009

AbstractThe 1,3‐dipolar cycloaddition reaction of 1‐substituted‐1,2,3,4‐tetrahydropyridines4a‐dwith organic azides5afforded the respective 1‐substituted‐piperidylidene‐2‐sulfonamides6. In contrast, the reaction of (E)‐1‐(1‐propenyl)‐1,2,3,4‐tetrahydropyridine (4e) with 4‐chlorobenzenesulfonyl azide yielded6mas well as 1‐(4‐chlorophenyl)sulfonimine‐1,2,3,4‐tetrahydropyridine (7) arising from addition of the azide to the (E)‐1‐(1‐propenyl) substituent of4e.
A new and convenient synthesis of N‐substituted perhydroazepines from adipaldehyde and primary amines with tetracarbonylhydridoferrate, HFe(CO), as a selective reducing agent
Authors: Shim Sang Chul , Doh Chil Hoon , Kim Tae Jeong , Lee Hak Ki , Kim Ki Doo 
Published: April 2009

AbstractEthanolic tetracarbonylhydridoferrate combined with adipaldehyde is very efficient for the selective transformation of an amino group into perhydroazepine. A large variety of both aliphatic and aromatic amines react with adipaldehyde in the presence of tetracarbonylhydridoferrate at room temperature and carbon monoxide to give the corresponding N‐alkyl‐ and N‐arylperhydroazepines in good to excellent yields.
Synthesis of cis‐4‐methyl‐3‐phenylpyrrolidines as potential dopaminergic agonists
Authors: Crider A. Michael , Sylvestri Susan C. , Tschappat Kathryn D. , Dick Ronald M. , Leader W. Greg 
Published: April 2009

Abstractcis‐3‐(3,4‐Dihydroxyprienyl)4‐methyl‐1‐(n‐propyl)pyrrolidine (23) was synthesized and evaluated for dopaminergic activity. The synthesis of 23 involved selective 4‐acylation of the 3‐phenylpyrrolidine‐2,5‐dione 15 and cis‐addition of hydrogen to a 4‐methyl‐3‐phenyl‐3‐pyrroline 4. Pharmacological evaluation of 23 showed that introduction of a cis‐4‐methyl group into the 3‐phenylpyrrolidine nucleus decreases dopaminergic activity.
Chemistry of Peri‐condensed pyrroles. Synthesis of 4H‐naphtho[1,4‐def]carbazole. A new route to nitrotriphenylenes
Authors: Klemm L. H. , Hall Eliot , Sur Sandip K. 
Published: April 2009

AbstractReaction of 1‐nitrotriphenylene (7a) with triethylphosphite (Cadogan reaction) produces 4H‐naphtho[1,4‐def]carbazole, a likely component of fossil fuels. Surprisingly 7a and its 2‐isomer are obtained from treatment of triphenylene with sulfuric acid/trifluoroacetic anhydride in nitromethane. Correlation between ultraviolet spectra and substitution reactions in peri‐condensed pyrroles and thiophenes is presented.
A facile route to 4,5,6,7‐tetrahydrothiophenes and benzothiophenes
Authors: Nishio Takehiko , Okuda Norikazu , Kashima Choji 
Published: April 2009

Abstract2‐Substituted tetrahydro‐ and cyclopentathiophenes 2 were produced in high yields by treatment of the semi‐cyclic trisubstituted 1,4‐diketones 1 such as 2‐phenacylcyclohexan‐1‐one, 2‐acetonylcyclohexan‐1‐one, and 2‐phenacylcyclopentan‐1‐one, with Lawesson's reagent.
Reactions of pyridinium or isoquinolinium ketene dithioacetals with aromatic N‐imines and S‐imines
Authors: Tominaga Yoshinori , Hosomi Akira 
Published: April 2009

AbstractReactions of ketene dithioacetals, 1‐[1‐substituted 2,2‐bis(methylthio)ethenyl]pyridinium 1a‐i or ‐isoquinolinium 2a,b iodides with aromatic N‐imines, 1‐aminopyridinium 3a‐1,1‐aminoquinolinium (4), and 2‐amino‐isoquinolinium (5) mesitylene sulfonates gave the corresponding 2‐methylthioimidazo[1,2‐a]pyridines 9a‐k, 2‐methylthiopyrazolo[1,5‐a]pyridines 11a‐q, 2‐methylthioimidazo[2,1‐a]isoquinoline derivatives 10a,b and 2‐methylthiopyrazolo[1,5‐a]quinoline (12). The benzoyl compounds, 1‐[1‐benzoyl‐2,2‐bis(methylthio)ethenyl]‐pyridinium iodides 1g,h,i reacted with N‐imine 3a to give the 3‐benzoyl‐2‐methylthioimidazo[1,2‐a]pyridines 9h‐k. The reaction of pyridinium ketene dithioacetals 1a,f,g (R1 = COOEt, COPh, and CN) with substituted pyridinium N‐imines having an electron‐withdrawing group on the pyridine ring afforded only the corresponding pyrazolo[1,5‐a]pyridine derivatives 11j‐r in good yields. Reactions of ketene dithioacetals with various S‐imines are also described. Possible mechanisms for the formation of 9 and 11 are described.
A rare case of three rearrangements during the cycloaddition‐elimination reaction of 4‐methyl‐5‐phenylimino‐Δ2‐1,2,3,4‐thiatriazoline with 2‐pyridyl isothiocyanate
Authors: L'abbé Gerrit , Allewaert Kathy , Toppet Suzanne 
Published: April 2009

Abstract2‐Pyridyl isothiocyanate (7), with its electrophilic and basic properties, gives a series of ring‐transformation reactions with 4‐methyl‐5‐phenylimino‐1,2,3,4‐thiatriazoline (1) at 60°. Two dithiazolidines, 8 and 10, are formed as major products at an early stage of the reaction, whereas two thiadiazolidines, 9 and 11, predominate at the end. The mechanism (Schemes II and III) has been elucidated by following the reaction course under a variety of conditions and by analyzing the products by 13C nmr spectroscopy.
The reactions of thiosemicarbazides and 5‐halovalerophenones
Authors: Kane John M. , Stewart Kenneth T. 
Published: April 2009

Abstract5‐Halovalerophenones reacted with substituted thiosemicarbazides affording two different heterocyclic ring systems. Reactions with 4‐substituted thiosemicarbazides gave 3‐aryl‐4,5,6,7‐tetrahydro‐1H‐1,2‐diazepine‐1‐carbothioamides whereas reactions with 2,4‐dimethylthiosemicarbazide gave hexahydro‐1,3‐dimethyl‐8a‐aryl[1,2,4]triazolo[1,5‐a]pyridine‐2(3H)‐thiones.
Synthesis and aldose reductase inhibitory activity of N‐1,N‐4‐disubstituted 3,4‐dihydro‐2(1H)‐quinoxalinone derivatives
Authors: Sarges Reinhard , Lyga John W. 
Published: April 2009

AbstractSynthetic routes have been developed for the preparation of 4‐acylated, 4‐benzenesulfonylated, and 4‐methylated 3,4‐dihydro‐2(1H)‐quinoxalinone‐1‐acetic acids. One example of the corresponding propionic acid has also been made. These compounds have been evaluated for their ability to inhibit bovine lens aldose reductase in vitro. Some members from this series also show weak activity in vivo, inhibiting sorbitol formation in sciatic nerves of streptozotocin‐diabetic rats.
Syntheses d'aryltetrahydropyrannyl ethers
Authors: Cottet Françoise , Cottier Louis , Descotes Gérard , Srivastava Rajendra Mohan 
Published: April 2009

AbstractL'addition de méthoxyphénols1sur le dihydropyranne en milieu acide donne des produitsC‐ et/ouO‐tétrahydropyrannylés3et4dont le pourcentage est fonction du nombre de substituants méthoxy et de la force du catalyseur acide. Les aryl tétrahydropyrannyléthers, orthocarbonylés9sont obtenus selon une réaction de Mitsunobu. Les rendements dependent de la nature des substituants sur les composés aromatiques et hétérocycliques.
On triazoles. XVII. The reaction of 5‐amino‐1,2,4‐triazoles with N‐heterocyclic β‐oxo‐esters
Authors: Reiter József , Rivó Endre 
Published: April 2009

AbstractPyrrolo[3,4‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidinone (3d), pyrido[3,4‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidinone (3e) and pyrido[4,3‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidinone (4e) derivatives representing three new ring systems were synthesised. Their structure was proved by comparing their uv and cmr spectra with those of the known benzo‐ and thieno‐1,2,4‐triazolo[1,5‐a]pyrimidinones used as model compounds.
Structural studies of bicyclomycin
Authors: Kohn Harold , Abuzar Syed , Korp James D. , Zektzer Andrew S. , Martin Gary E. 
Published: April 2009

AbstractThe complete 1H and 13C nmr assignments for both bicyclomycin (1) and bicyclomycin‐3′‐ethyl carbamate (2) were achieved through the combined use of a series of nmr techniques. Extensive use of the long range heteronuclear multiple quantum chemical shift correlation experiment (HMBC) permitted the assignments of all the exchangeable protons as well as the 2,5‐piperazinedione carbonyl carbons in both compounds. The X‐ray crystallographic structure of 2 was determined and compared to the reported structure of bicyclomycin. Compound 2 crystallizes in the orthorhombic space group P212121 with four molecules in a unit cell having dimensions a = 7.931(2), b = 10.834(4), and c = 24.468(7) Å. The structure refined to a final R value of 6.2%.
Synthesis and studies of piperidinone, the major metabolite of a new antidepressant drug S 3344
Authors: Berthelot Pascal , Vaccher Claude , Devergnies Monique , Flouquet Nathalie , Debaert Michel 
Published: April 2009

AbstractThe synthesis of 1‐(4‐fluorobenzyl)‐6‐isopropyl‐2‐piperidinone 7a, a major metabolite of a new antidepressant S 3344, is described and then substituted with various substituents. The 1H and 13C nmr provide information on their structure.
Synthesis and in vitro biological activity of some 7‐[hydrazino], ‐[hydrazonyl] and ‐[pyrazolyl]quinolone‐3‐carboxylic acids
Authors: Ziegler Carl B. , Kuck Nydia A. , Harris Sonja M. , Lin Yang‐I 
Published: April 2009

Abstract1‐Ethyl‐6‐fluoro‐7‐hydrazino‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acid (8) has been prepared and served as a versatile intermediate from which a number of hydrazone, pyrazole and dihydropyridazine derivatives were synthesized. The in vitro biological activity of some of these derivatives is reported.
Synthesis of 8,9‐difluoro‐2‐methyl‐6‐oxo‐1,2‐dihydropyrrolo[3,2,1‐ij]quinoline‐5‐carboxylic acid
Authors: Parikh Vinod D. , Fray Andrew H. , Kleinman Edward F. 
Published: April 2009

AbstractA new and efficient seven‐step synthesis of 8,9‐difluoro‐2‐methyl‐6‐oxo‐1,2‐dihydropyrrolo[3,2,1‐ij]‐quinoline‐5‐carboxylic acid (9), an important intermediate used in the synthesis of quinolone antibacterials, has been developed beginning with commercially available 2,3,4‐trifluoronitrobenzene. Selective displacement of the 2‐fluorine of the starting material with the anion of ethyl acetoacetate and subsequent hydrolysis and decarboxylation affords the arylacetone derivative 11. Reduction of the ketone and nitro groups of 11 followed by condensation with diethyl ethoxymethylenemalonate gives 14, which is cyclized to the indole derivative 15 by the Mitsunobu procedure. Friedel‐Crafts cyclization of 15 and acid hydrolysis gives the title compound 9.
Asymmetric reaction. XV. Structure and relative configuration of a reductive dimerization product of ethyl phenylglyoxylate, diethyl diphenyltartrate
Authors: Ohgo Yoshiaki , Kimura Michio , Takeuchi Seiji 
Published: April 2009

AbstractThe hydrogenation of ethyl phenylglyoxylate catalyzed by bis(dimethylglyoximato)cobalt(II)‐quinine gave a novel reductive dimerization product, diethyl diphenyltartrate, with a slight optical activity. The crystals obtained from its benzene‐hexane solution were investigated by X‐ray diffraction method. The crystal is triclinic, space group p1, a = 10.078(3), b = 10.283(2), c = 9.781(3) Å, α = 109.80(2), β = 102.35(3), γ = 78.50(2)°, Z = 2, V = 922.7 Å3, Dc = 1.29 g cm−3,μ = 7.46 cm−1 for Cu Kα. The structure was solved by the direct method, and refined by a block‐diagonal least‐squares procedure: R = 0.059 for 2568 reflections with | Fo | >3σ(| Fo | ). The relative configuration around the two chiral carbons indicated that the molecule is in the threo‐form, and the Newman projection showed that the molecule has the staggered conformation. There were two relatively strong intramolecular hydrogen bonds between the two hydroxyl groups and the two carbonyl oxygen atoms of ethoxycarbonyl groups.
Total assignment of the proton NMR spectrum of dinaphtho[1,2‐B:2′,3′‐d]thiophene
Authors: Johnston Milton D. , Martin Gary E. , Castle Raymond N. 
Published: April 2009

AbstractRecently, there has been some question regarding the 1H‐nmr spectrum of dinaphtho[1,2‐b‐2′,3′‐d]‐thiophene. A recent study has reported differences in some of the proton resonance positions from results of earlier work. We report the total assignment of the 1H‐nmr spectrum of the title compound using a combination of 1H‐COSY and one dimensional NOE‐difference spectroscopy (NOEDS).
Synthesis of a pyrrolo annulated pyrido[2,3‐D]pyrimidine as a potential nonclassical antifolate
Authors: Gangjee Aleem , Patel Jasmin , Lin Fu‐Tyan 
Published: April 2009

AbstractCyclocondensation of 2,4,6‐triaminopyrimidine (4) with ethyl N‐benzyl‐4‐oxo‐3‐pyrrolidine carboxylate (5) in diphenyl ether regiospecifically afforded a new tricyclic, angular 1,3,8‐trisubstituted pyrrolo[3′,4′:4,5]‐pyrido[2,3‐d]pyrimidine‐6‐one 1 in excellent yield. The ketoester 5 was prepared by a literature method. Compound 1 in addition to being a new heterocyclic system is an important key precursor to a variety of classical and nonclassical tricyclic, 5‐deaza analogues of the folate cofactor 5,10‐methylenetetrahydrofolate 3.