bluuebunny/crossref_metadata_2025 huggingface dataset:
The synthesis of condensed 1,3,5‐triazinium perchlorates from diazaiminium intermediates
Authors: Okide George B.
Published: March 2009

The known azaiminium intermediate, 1‐chloro‐1,3‐bis(dimethylamino)‐3‐phenyl‐2‐azaprop‐2‐en‐1‐ylium perchlorate 1[1], reacts with 2‐aminothiazole to yield the fully conjugated condensed 1,3,5‐triazinium salt 7. Various suitably substituted heterocyclic compounds react similarly to afford the corresponding condensed 1,3,5‐triazinium salts. The diazaiminium intermediates 2–5 obtained from several secondary amides give identical products when treated with the same starting compounds. The procedure appears to be of wide application.
Reaction of 3‐nitro‐ and 3‐diethylphosphonocoumarin with phenacyl bromide. X‐ray molecular structure of 3‐nitro‐3,4‐phenacylidenecoumarin
Authors: Rodios Nestor A. , Bojilova Anka , Terzis A. , Raptopoulou C. P.
Published: March 2009

3‐Nitro‐ and 3‐diethylphosphonocoumarins 4a,b react with phenacyl bromide stereoselectively under phase‐transfer conditions, in the presence of a base and of a transfer agent, to give the cyclopropyl derivatives 6 and 7 in good yields. A mechanistic explanation is given for the stereoselectivity of the reaction. The X‐ray molecular structure of compound 6a is also presented.
Intramolecular diels‐alder reactions. 4. Additions to naphthalene
Authors: Ciganek Engelbert , Wuonola Mark A. , Harlow Richard L.
Published: March 2009

N‐Methyl‐N‐2‐propynyl‐1‐naphthalenecarboxamide, N‐methyl‐N‐2‐propynyl‐1‐naphthaleneacetamide, and N‐methyl‐N‐3‐butynyl‐1‐naphthalenecarboxamide undergo intramolecular Diels‐Alder reactions at 190°, 250°, and 270° to give lactams 1,6, and 9, respectively. The cyclization temperatures are higher by 80‐120° as compared to those of the corresponding anthracene derivatives. Elaboration of lactam 6 gave the trans‐4a‐aryldecahydroisoquinoline derivative 7a which, as the (‐) isomer, was shown to have the same absolute stereochemistry as morphine.
Methoxide ion mediated reactions of methyl azidoacetate with 4‐and 2‐cyanobenzaldehyde. An unexpected cyclization of the ortho isomer to a 2(1H)‐benzazepine derivative
Authors: Kiselyov Alexander S. , Van Aken Koen , Gulevich Yuri , Strekowski Lucjan
Published: March 2009

A condensation reaction of 4‐cyanobenzaldehyde (1) with methyl azidoacetate (2) in the presence of sodium methoxide produces a mixture of geometrical isomers of azidocinnamates 3 which undergoes thermolysis to give an indole 4. By contrast, the treatment of 2‐cyanobenzaldehyde (5) with 2 in the presence of sodium methoxide and followed by the usual workup furnishes an azepine derivative 6.
3′‐Keto‐1‐nitro‐2‐phenylspiro[cyclopropane‐3,2′‐quinuclidine]: Synthesis and reactions with nucleophiles
Authors: Besidsky Yevgeny , Luthman Kristina , Hacksell Uli
Published: March 2009

3′‐Keto‐1‐nitro‐2‐phenylspiro[cyclopropane‐3,2′‐quinuclidine] was synthesized by a two‐step procedure from 2‐benzylidenequinuclidin‐3‐one. Ring‐opening reactions of the cyclopropane ring using a variety of N‐, O‐, and C‐nucleophiles (amines, methoxide, nitromethanate, cyanide anions, and lithium diphenylcopper) were studied, and a general mechanism for the transformations is proposed.
The formation of pyrazolo[1,5‐a]pyrimidines by the reaction of 3‐(4‐chlorophenyl)pyrazol‐5‐amine with chalcones
Authors: Quiroga Jairo , Insuasty Braulio , Rincon Ricardo , Larrahondo Marina , Hanold Norbert , Meier Herbert
Published: March 2009

Cyclocondensation reactions of the pyrazol‐5‐amine 1 and the 1‐aryl‐3‐phenyl‐2‐propen‐1‐ones 2a‐d yield the 6,7‐dihydropyrazolo[1,5‐a]pyrimidines 7a‐d. Whereas 7a‐c can be isolated in pure state, 7d is subjected to a spontaneous oxidation.
Electron impact mass spectrometry of new tris(polyoxalkyl)amines (tridents)
Authors: Corda Luciana , Delogu Giovanna , Maccioni Elias , Podda Gianni , Fernandez Josè Manuel Blanco
Published: March 2009

The mass spectrometric behavior of new tris(polyoxalkyl)amines (tridents) 1–5 have been studied and compared with N‐(3,6,9,12‐tetraoxatridecyl)‐16‐aza‐18‐crown‐6 (6) and 1‐morpholino‐3,6,9‐trioxadecane (7). The peculiar fragmentation patterns are emphasized.
Fused lactones as a route to functionalized 1‐substituted indoles
Authors: Schuster Herbert F. , Coppola Gary M.
Published: March 2009

Indole lactones 8 and 14 were synthesized as a means of functionalizing the 1‐isopropyl substituent of the indole nucleus. Lactone 8, upon reduction with diisobutylaluminum hydride, produces lactol 9 which behaves like a masked hydroxy aldehyde and undergoes a Horner‐Emmons reaction with triethyl phosphonoacteate to give α,β‐unsaturated ester 3 which possesses a hydroxyl group on the 1‐isopropyl moiety.
New [g]‐fused [1,2,4]triazolo[1,5‐c]pyrimidines: Synthesis of pyrido[3,2‐e] and [4,3‐e][1,2,4]triazolo[1,5‐c]pyrimidine, pyrimido[5,4‐e][1,2,4]triazolo[1,5‐c]pyrimidine and [1,2,4]triazolo[1,5‐c]pteridine derivatives
Authors: Giudice Maria Rosaria Del , Borioni Anna , Mustazza Carlo , Gatta Franco
Published: March 2009

A number of 2‐aryl‐substituted pyrido[3,2‐e] and [4,3‐e][1,2,4]triazolo[1,5‐c]pyrimidines and [1,2,4]triazolo[1,5‐c]pteridines 11,12a,b,e, their corresponding 5‐carbonyl derivatives 7,8a,b,e and some pyrimido[5,4‐e][1,2,4]triazolo[1,5‐c]pyrimidin‐5‐ones 7,8c,d have been synthesized, according to different pathways. The new tricyclic heterocycles were prepared with the aim of studying their possible benzodiazepine receptors affinity.
Preparation and alkylation of regioisomeric tetrahydrophthalimide‐substituted indolin‐2(3H)‐ones
Authors: Karp Gary M. , Condon Michael E.
Published: March 2009

A series of novel regioisomeric tetrahydrophthalimide‐substituted indolin‐2‐ones has been prepared via the Sommelet‐Hauser type cyclization of appropriately substituted anilines as potential herbicides. The resultant indolin‐2‐ones were then regioselectively alkylated at N‐1 and C‐3 to give 1,3,3‐trisubstituted indolin‐2‐ones. The most active series was also prepared by the bis‐nitration of m‐fluorophenylacetic acid followed by reduction and cyclization to give 6‐amino‐5‐fluoroindolin‐2‐one. Elaboration to the tetrahydrophthalimide‐substituted indolin‐2‐one was followed by C‐ and N‐alkylation to give the desired compounds.
Tetrazole compounds. 9. A new approach to tetrazolyl‐substituted quinoline derivatives
Authors: Fischer Gerhard W.
Published: March 2009

The acid‐catalyzed reaction of 1‐aryl‐5‐(2‐dimethylaminovinyl)‐1H‐tetrazoles 2 with arylamines suitably functionalized in the ortho‐position resulted in Z‐configurated transamination products which were cyclized to novel 3‐tetrazolylquinolines by the action of sodium ethoxide. Thus, on reacting 2 with 2‐aminoacetophenone or 2‐aminobenzophenone, respectively, the 2‐[2‐(1‐aryl‐1H‐tetrazol‐5‐yl)vinyl‐amino]aryl ketones 3a‐g were obtained, the cyclization of which gave 4‐substituted 3‐(1‐aryl‐1H‐tetrazol‐5‐yl)quinolines 4. In the case of the transamination products 3h‐1, prepared from 2 and methyl anthranilate, the ring closure afforded 3‐(1‐aryl‐1H‐tetrazol‐5‐yl)‐1H‐quinolin‐4‐ones 5. Starting from 2 and anthranilonitrile 4‐amino‐3‐(1‐aryl‐1H‐tetrazol‐5‐yl)quinolines 10 were obtained via the corresponding intermediates 9.
Synthesis of 1,4‐dihydro‐4‐oxopyridazino[1,6‐a]indole‐3‐carboxylic acids and 1,4‐dihydro‐4‐oxopyrido[3′,2′:4,5]pyrrolo[1,2‐b]‐pyridazine‐3‐carboxylic acids as potential antibacterial agents
Authors: Ruxer J. M. , Lachoux C. , Ousset J. B. , Torregrosa J. L. , Mattioda G.
Published: March 2009

A few aza analogues of the quinolones have been prepared in the two families of the 1,4‐dihydro‐4‐oxopyridazino[1,6‐a]indole‐3‐carboxylic acids and the 1,4‐dihydro‐4‐oxopyrido[3′,2′:4,5]pyrrolo[1,2‐b]‐pyridazine‐3‐carboxylic acids to check their antibacterial potential. One compound 6c shows antibacterial activities of the level of nalidixic acid and represents a new lead structure differing from the classical quinolones.
New organic nitrates. I. Synthesis of 1,3‐benzoxazine‐2,4‐dione, 1,3‐benzoxazine‐2‐thion‐4‐one, 1,3‐benzothiazine‐2,4‐dione and quinazoline‐2,4‐dione derivatives
Authors: Benedini Francesca , Bertolini Giorgio , Ferrario Francesco , Guindani Roberto , Sala Alberto
Published: March 2009

The preparation and the physico‐chemical characterization of new heterocyclic organic nitrates containing 1,3‐benzoxazine‐2,4‐dione, 1,3‐benzoxazine‐2‐thion‐4‐one, 1,3‐benzothiazine‐2,4‐dione and quinazo‐line‐2,4‐dione moieties, are reported.
Reactions of activated aryl sydnones with electrophiles
Authors: Turnbull Kenneth , Blackburn Thomas L. , McClure Diane B.
Published: March 2009

Electrophilic substitution on the aryl or sydnone ring of some ortho‐substituted activated N‐aryl‐sydnones is reported.
Substituent effects on the tautomer ratios between the hydra‐zone imine and diazenyl enamine forms in 3‐(arylhydra‐zono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines. Correlation of the hammett constants σp with the tautomeric equilibrium constants KT
Authors: Kurasawa Yoshihisa , Hosaka Tomoyoshi , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa
Published: March 2009

The 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines 1a‐e and 2a‐i showed tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in dimethyl sulfoxide media. The sub‐stituent effects on the tautomer ratios of A to B in compounds 1a‐e and 2a‐i were studied by the nmr spec‐troscopy. The electron‐donating or electron‐withdrawing p‐substituents R1 in compounds 2a‐i represented a tendency to increase the ratios of the tautomer A or the tautomer B, respectively, exhibiting the linear correlation of the Hammett constants σp (‐0.17 to +0.78) with the tautomer ratios of A to B or the tautomeric equilibrium constants KT. However, the presence of the ester group R2 in compounds 1a‐e induced the exclusive existence of the tautomer A regardless of the nature of the p‐substituents R1. In the tautomeric thermodynamic study, the elevating temperature increased the ratios of the hydrazone imine tautomer A in compounds 2a‐i. The tautomeric thermodynamic parameters ΔG°, ΔH° and ΔS° were derived from the van't Hoff plots for compounds 2a,b,h,i, wherein the entropy term dominated the free‐energy difference between the A and B tautomers.
Preparation, structural characterization, and acid‐catalyzed isomerization of 3‐, 7‐, and 9‐benzyl‐6‐benzylthiopurines
Authors: Huang Jim J. , Ragouzeos Aris , Rideout Janet L.
Published: March 2009

Benzylation of 6‐benzylthiopurine was examined. Structural assignments of the products were determined by 1‐D and 2‐D nmr spectroscopy (HMQC, HMBC, and nOe). In the presence of base, the isomeric N3‐, N7‐, and N9‐benzylated products 4, 3, and 2 were isolated; however, only 9‐benzyl‐6‐benzylthio‐purine (2) was obtained in the absence of base. In the latter case, the initially formed N3‐ and N7‐isomers were, in the presence of acid, converted to 9‐benzyl‐6‐benzylthiopurine (2) via a 6‐benzylthiopurine intermediate as evidenced by analysis of the reaction over time using reversed‐phase hplc.
AM1 semiempirical searching for suitable thiophene derivatives that will enable thiophenes to act as a diene in the diels‐alder reactions
Authors: Jursic Branko S. , Coupe Don
Published: March 2009

The AM1 semiempirical method was used for theoretical searching of activation of thiophene as a diene for the Diels‐Alder reaction. The reactivity of thiophene, electron‐withdrawing and electron‐donating substituted thiophenes, as well as the S‐methylthiophenium ion were studied as the diene for Diels‐Alder reactions by evaluating their frontier orbital energies and by calculating reaction barriers with activated and deactivated dienophiles. It was demonstrated that slight activation of the thiophene ring can be obtained with both electron‐donating and electron‐withdrawing groups attached to the thiophene ring. It was predicted that the actual transformation of thiophenes into the corresponding S‐methylthiophenium anions is the best means of activating the thiophenes. The calculated activation energies for normal (non‐activated) dienophiles are moderate so mild reaction conditions are predicted. If dienophiles are activated with electron‐donating substituents, AM1 calculations predict a two step cycloaddition reaction with a very small activation barrier.
Ring transformations of heterocyclic compounds. X. A simple method for the conversion of methyl substituted pyridinium salts into 2,4,6‐triarylphenyl derivatives: The first (thio)pyrylium ring transformations with heterocyclic anhydrobases as carbon nucleophiles
Authors: Zimmermann Thomas
Published: March 2009

The synthesis of 2,4,6‐triarylphenylpyridinium perchlorates 3 from methyl substituted derivatives 2 by a 2,6‐[C5+C] ring transformation of 2,4,6‐triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid in ethanol is reported. Spectroscopic data of the pyridinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.
Synthesis of coumarin‐3‐O‐acylisoureas by dicyclohexylcarbodiimide
Authors: Bonsignore Leonardo , Cottiglia Filippo , Maccioni Anna M. , Secci Daniela , Lavagna Silvio M.
Published: March 2009

The synthesis and isolation of some O‐acylisoureas are described. The reaction between dicyclohexyl‐carbodiimide and coumarin‐3‐carboxylic acids leads to coumarin‐dicyclohexylisourea derivatives, isolated as the main products, and to coumarin‐dicyclohexylurea derivatives as byproducts.
Syntheses and photophysical properties of fluorescent dibenzofurans, a dibenzothiophene, and carbazoles substituted with benzoxazole and hydroxyl groups to produce excited state intramolecular proton‐transfer
Authors: Kauffman Joel M. , Litak Peter T. , Boyko Walter J.
Published: March 2009

Dibenzofurans, a dibenzothiophene, and carbazoles, each substituted with a 2‐benzoxazolyl group as well as an ortho‐hydroxyl group, were synthesized to produce fluors with fluorescence due to excited‐state intramolecular proton‐transfer. The orientations for Friedel‐Crafts acylation of 3‐methoxydibenzothio‐phene and of the analogous carbazole were determined. The fluors displayed absorption peaks in the 330–385 nm region with molar extinction coefficients up to 57,000. Fluorescence quantum efficiencies of 0.17–0.44 were obtained at wavelengths that had peak values from 540–600 nm. The fluors are of potential use as wavelength shifters in scintillating polystyrene fibers.
15N chemical shifts and long‐range 1H‐15N coupling pathways of selected strychnos alkaloids
Authors: Martin Gary E. , Crouch Ronald C. , Andrews C. Webster
Published: March 2009

The Strychnos alkaloids have been the focal point of considerable synthetic and spectroscopic effort. We now report the 15N chemical shifts and long‐range 1H‐15N coupling pathways of strychnine, brucine, and holstiine at natural abundance. Long‐range coupling pathways were established using a gradient‐enhanced HMQC sequence optimized for the observation of 1H‐15N long‐range couplings.
Long‐range 1H‐15N couplings and 15N chemical shift assignments of the bis‐indole anticancer drug navelbine®
Authors: Martin Gary E. , Crouch Ronald C.
Published: March 2009

The recently reported application of gradient‐enhanced HMQC for the observation of long‐range 1H‐15N heteronuclear couplings at natural abundance has been extended to the bis‐indole anticancer drug Navelbine®. Responses correlating protons to N16′ (δ 15N 138.2 ppm)in the velbanamine subunit and N1 and N9 (δ 15N 66.0 and 55.3 ppm, respectively) in the vindoline subunit were observable within about 4 hours of data acquisition. The single response to N6′ (δ I5N 43.0 ppm), in contrast, was very weak requiring a weekend data acquisition to even be observed. The difficulty in observing correlations to N6′ is presumably a function of molecular mobility in the eight‐membered azocine ring.
Synthesis of thieno[2′,3′(3′,4′ or 3′,2′):5,6]azepino[2,1‐a]isoindolediones from N‐Thienyl‐2(3)‐ylmethylphthalimides
Authors: Pigeon Pascal , Decroix Bernard
Published: March 2009

Reduction of N‐thienybnethylphthalimides 5a‐e followed by the Wittig reaction gave the substituted acetic acids 8a‐e. Their corresponding acyl chlorides where cyclized in the presence of aluminium trichloride to furnish the cyclic ketones 9a‐e. Treatment of these ketones with bromine followed by triethylamine, or with selenium dioxide led to the thienoazepinoisoindolediones 1a‐e.
Preparation and regiochemical assignments of new pyrazolo[3,4‐c] [2,1]benzodiazepines
Authors: Arranz Esther , Díaz Juan A. , Morante Esther , Pérez Carmen , Vega Salvador
Published: March 2009

The preparation of new pyrazolo[3,4‐c][2,1]benzothiazepines substituted at the nitrogen atoms of the pyrazole moiety is described. It was carried out by reaction of the 4,9‐dihydro‐9‐methyl‐4,10,10‐trioxo‐1(2)H‐pyrazolo[3,4‐c][2,1]benzothiazepine (1) with several alkylating agents under both classical and phase‐transfer catalysis (PTC) conditions. Assignments of theN‐alkyl regioisomers obtained were performed by study of their1H nmr spectra and NOE experiments.
Steroidal oxazoles, oxazolines, and oxazolidines
Authors: Camoutsis Charalambos
Published: March 2009

In recent years the interest of this investigator has been attracted to a series of new compounds in which a cyclopentanoperhydrophenanthrene system is condensed with various heterocyclic rings. As was to be expected, the addition of heterocycles to steroids often leads to a change of their physiological activity and the appearance of new interesting biological properties. Since the numerous data on the synthesis and properties of the steroidal oxazoles, oxazolines, and oxazolidines are scattered, this stimulated us to write the present review, in which the literature published up to the end of 1994 is systematized.
Synthesis of substituted furo[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidines and furo[3,2‐e]tetrazolo[1,5‐c]pyrimidines
Authors: Lockhart Christopher C. , Sowell J. Walter
Published: March 2009

A series of substituted furo[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidines and furo[3,2‐e]tetrazolo[1,5‐c]pyrimidines were obtained from reactions of substituted 2‐dimemylamino‐4‐hydrazmofuro[2,3‐d]pyrimidines with orthoesters or sodium nitrite in acetic acid, respectively.
Ring closure reactions of cyclic 2‐arylaminomethylene‐1,3‐diones
Authors: Van Tinh Dang , Fischer Michaela , Stadlbauer Wolfgang
Published: March 2009

5‐Arylaminomethylene compounds such as 5‐arylaminomethylenepyrimidine‐2,4,6‐triones 2 or 2‐phenylaminomethylenephenalene‐1,3‐dione 13 cyclize by thermolysis via migration of the arylamino group to pyrimido[4,5‐b]quinoline‐2,4‐diones 6 or 7‐oxo‐7H‐naphtho[1,8‐bc]acridine 15, respectively. 2‐Phenylaminomethylenecyclohexane‐1,3‐dione 8 cyclizes to 9,9‐dimethyl‐9,10‐dihydrophenanthridin‐7(8H)‐one 11 without rearrangement.
The synthesis of novel polycyclic heterocyclic ring system via photocyclization. 18. Benzo[h]naphtho‐[1′,2′:4,5]thieno[2,3‐c]quinoline and benzo[h]naphtho‐[1′,2′:4,5]thieno[2,3‐c] [1,2,4]triazolo[4,3‐a]quinoline
Authors: Luo Jiann‐Kuan , Federspiel Ronald F. , Castle Raymond N.
Published: March 2009

The synthesis of two previously unknown polycyclic ring systems, benzo[h]naphtho[1′2′:4,5]‐thieno[2,3‐c]quinoline (1) and benzo[h]naphtho[1′,2′:4,5]thieno[2,3‐c][1,2,4]triazolo[4,3‐a]quinoline (2), was achieved via oxidative photocyclization of 1‐chloro‐N‐(1‐naphthyl)naphtho[2,1‐b]thiophene‐2‐carboxamide (5). The total assignment of their 1H and 13C nmr spectra was determined by the concerted use of two‐dimensional nmr methods.
Ring closure reactions of azidouracils to oxazolo‐ and isoxazolopyrimidines
Authors: Van Tinh Dang , Stadlbauer Wolfgang
Published: March 2009

Thermolysis of 6‐azidouracils 1 in the presence of polyphosphoric acid leads either to oxazolo[5,4‐d]pyrimidine‐5,7‐diones 5 (by reaction with benzoic acid 2a) or to isoxazolo[3,4‐d]pyrimidine‐4,6‐diones 7 (by reaction with aliphatic carboxylic acids 2b,c). 5‐Benzoylpyrimidinetriones 12 could be shown to cyclize to isoxazolo[5,4‐d]pyrimidine‐4,6‐diones 15 by chlorination with phosphorus pentachloride and subsequent reaction with sodium azide.
The estimation of the aromaticity of five‐membered and benzo fused five‐membered rings by the hybrid DFT computed magnetic properties
Authors: Jursic Branko S.
Published: March 2009

The structures of thiophene, pyrrole, furan, and their benzo derivatives were generated with the hybrid B3LYP density functional theory (DFT) methods employing a 6‐31G* basis set. Their magnetic susceptibility anisotropics were calculated on these geometries with a continuous set of gauge transformations. The aromaticity of the heterocycles was discussed in light of their structural uniformity and magnetic susceptibility. The computed structural parameters, order of aromaticity, stability, and reactivity is in excellent agreement with the experimental results. The usefulness of this approach to determine the reactivity is discussed.
The synthesis and reactions of 4‐(2‐ and 3‐thienyl)‐tetrahydroisoquinolines
Authors: Tupper David E. , Hotten Terrence M. , Prowse William G.
Published: March 2009

Tetrahydroisoquinoline derivatives substituted in the 4‐position by either a 2‐ or 3‐substituted thiophene ring have been synthesised. Simple electrophilic substitution reactions of these systems take place as expected in the α‐position of the thiophene ring. Metalation reactions are more complex and take place at the benzylic 4‐position of the tetrahydroisoquinoline nucleus in the case of the 2‐substituted thiophene derivatives or at either the thiophene α‐positions or the benzylic 4‐position depending on the nature of the attacking electrophile in the case of the 3‐substituted thiophene system.
Synthesis of 2‐imino‐4‐thiazolines, 2‐imino‐4‐alkoxythiazolidines, thiazoles and 4‐imidazolin‐2‐ones from α‐halomethyl ketimines
Authors: De Kimpe Norbert , De Cock Wim , Keppens Marian , De Smaele Dirk , Mészáros Andrea
Published: March 2009

A variety of heterocycles, including 3,4‐disubstituted‐2‐imino‐4‐thiazolines, 3,4‐disubstituted‐4‐methoxy‐2‐iminothiazolidines, 2,4‐disubstituted‐thiazoles, 2‐amino‐4‐substituted‐thiazoles and 1,5‐disubstituted‐4‐imidazolin‐2‐ones, were synthesized from α‐chloromethyl and α‐bromomethyl ketimines by condensation with potassium thiocyanate, thiourea, ammonium thiocyanate and potassium cyanate.
The reaction of phenylglyoxal with 2‐aminoalcohols. Rearrangement of 2‐acyloxazolidines to 2‐hydroxy‐5,6‐dihydro‐1,4‐oxazines
Authors: Sheradsky Tuvia , Silcoff Elliad R.
Published: March 2009

The reactions of phenylglyoxal hydrate with (R)‐phenylglycinol and with (1S,2R)‐norephedrine were investigated. The expected 2‐benzoyloxazolidines 3 and 2a, respectively are initially formed, and undergo a fast, spontaneous stereospecific rearrangement to the corresponding 2‐hydroxy‐3‐phenyl‐5,6‐dihydro‐1,4‐oxazines 4 and 5 respectively. The mechanism of this new rearrangement is discussed. The structures and stereochemistry of 4 and 5 were established by X‐ray diffraction analysis.
Concurrent alkylation‐methoxylation of 4,5‐dihalopyridazin‐6‐ones and synthesis of 5‐halo‐4‐hydroxypyridazin‐6‐ones
Authors: Cho Su‐Dong , Choi Woo‐Yong , Yoon Yong‐Jin
Published: March 2009

1‐Alkyl‐5‐halo‐4‐methoxypyridazin‐6‐ones were synthesized from 1‐alkyl‐4,5‐dihalopyridazin‐6‐ones by the concurrent alkylation‐methoxylation. 1‐Alkyl‐5‐halo‐4‐hydroxypyridazin‐6‐ones were also prepared.
Functionalization of near‐infrared cyanine dyes
Authors: Strekowski Lucjan , Lipowska Malgorzata , Górecki Tadeusz , Mason J. Christian , Patonay Gabor
Published: March 2009

An indolium heptamethine cyanine dye 11 containing an isothiocyanate function for selective coupling of the dye chromophore with a primary amino group of proteins has been synthesized. Functionalization of a benzothiazolium heptamethine cyanine 12 is discussed.
Cyclization of 2‐ and 3‐indolythioalkanoic acids to novel indole‐containing tricyclic ring systems
Authors: Hamel Pierre , Girard Mario
Published: March 2009

A series of 2‐ and 3‐indolylthioalkanoic acids of various chain lengths were cyclized under dehydrative conditions affording tricyclic indole‐containing ring systems wherein the third ring contains a sulfur atom attached to the 2‐ or 3‐position of the indole ring. This methodology affords entry into the novel thiepino[3,2‐b]indole, thiocino[2,3‐b]indole and thiocino[3,2‐b]indole ring systems.
Application of the hurd‐mori‐reaction for the synthesis of tricyclic annelated 1,2,3‐thiadiazoles
Authors: Stanetty Peter , Kremslehner Manfred , Müllner Martin
Published: March 2009

The synthesis of methyl naphtho[1,2‐d][1,2,3]thiadiazole‐4‐carboxylate 1a as well as the corresponding thienobenzo[1,2,3]thiadiazoles 1b and 1c is reported using the Hurd‐Mori reaction in the key step. Treatment of the readily available tosylhydrazones 10a‐c with thionyl chloride surprisingly affords the fully aromatic products 1a‐c, instead of the expected annelated 4,5‐dihydro[1,2,3]thiadiazoles 2a‐c. Based on these results a mechanism for the aromatization step with thionyl chloride is proposed.
A convenient synthesis of 4‐amino‐3,5‐dialkyl‐4H‐1,2,4‐triazoles
Authors: Lkizler Aysun , Demirbas Neslihan , Lkizler Aykut A.
Published: March 2009

Ester tert‐butoxycarbonylhydrazones 2 were reacted with some carboxylic acid hydrazides to give 4‐terrtutoxycarbonylamino‐3,5‐dialkyl‐4H‐1,2,4‐triazoles 3–6. Treatment of 3–5 with 6 N hydrochloric acid under mild conditions resulted in the formation of 4‐ammo‐3,5‐dialkyl‐4H‐1,2,4‐triazole hydrochlorides 7–9 in good yields. Compound 7a was converted to the free 4‐amino compound 10a upon treatment with ethanolic sodium ethoxide solution.
Substitution reactions of phenanthro[9,10‐d]triazole with benzyl chlorides
Authors: Yasuda Goro , Kimoto Hiroshi
Published: March 2009

The reaction of the potassium salt of phenanthro[9,10‐d]triazole and benzyl chloride gave 2‐(benzyl)‐2H‐phenanthro[9,10‐d]triazole (2a) in 15% yield. The other regio‐isomer, 1‐(benzyl)‐1H‐phenanthro[9,10‐d]‐triazole (1a), was obtained as a by‐product in 3.9% yield. Similar reactions with benzyl chlorides having a methyl, a chloro or a nitro group on the aromatic ring gave the corresponding two products, 1b‐j and 2b‐j. In all cases, 2b‐j were major products in yields of 14–62%, 1b‐j were minor ones in yields of 1.4–7.6%. The structures of the isomers were confirmed by X‐ray crystal analyses.
Cyclization reactions of 2‐(2‐chloro‐4‐nitrophenylsulfonyl)‐1‐(2‐thienyl)ethanone
Authors: Fan Ai‐Long , Cao Song , Xu Jing‐Hua , Zhang Zheng
Published: March 2009

A new sulfonyl group‐containing heterocyclic compound 2‐(2‐chloro‐4‐nitrophenylsulfonyl)‐1‐(2‐thienyl)ethanone2was prepared from the corresponding sulfide 2‐(2‐chloro‐4‐nitrophenylthio)‐1‐(2‐thienyl)ethanone1. Two different cyclization reactions of the compound2were discussed. In contrast to the tandem alkylation‐cyclization process [1], another cyclic procedure was described. In the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as a base and dimethylformamide as a solvent, compound2was treated with ethyl acrylate or methyl methacrylate at 50–55° to give the 1,4‐benzoxathiin 4,4‐dioxide5or6respectivelyviaa tandem Michael conjugate addition‐cyclization process.
Conjugate addition of grignard reagents to N‐(α,β‐unsaturated)acylpyrazoles. Diastereoselective β‐alkylation using 3‐phenyl‐l‐menthopyrazole
Authors: Kashima Choji , Takahashi Katsumi , Fukusaka Kiyoshi , Hosomi Akira
Published: March 2009

The conjugate additions of N‐(α,β‐unsaturated)acylpyrazoles were carried out by the treatment with Grignard reagents in the presence of cuprous halides. The reaction of 2‐(α,β‐unsaturated)acyl‐3‐phenyl‐l‐menthopyrazoles 3a‐h occurred in higher chemical yields and with asymmetric inductions on β‐position, where the addition of magnesium bromide as a Lewis acid influenced to the yields and the diastereoselectivities. In the case of α‐methylated 2‐(α,β‐unsaturated)acyl‐3‐phenyl‐l‐menthopyrazoles 3i‐n, the excellent asymmetric induction on the α‐position was also observed through the diastereofacial protonation.
Synthesis of 4‐ and 5‐(s‐triazolo[4,3‐b]pyridazinyl‐3)‐substituted cyclic polyols
Authors: Turk Cvetka , Svete Jury , Golobič Amalija , Golič Ljubo , Stanovnik Branko
Published: March 2009

4(R)‐(6‐Chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐1,4‐furanoses 10 and 11, 5(R)‐(6‐chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐1,5‐pyranose 13, and 2(S),3(R)‐dihydro‐5‐(6‐chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐2,3‐O‐isopropylidenefuran (12) were prepared by cyclization of hydrazones 6–9 obtained from 6‐chloro‐3‐hydrazinopyridazine (1) and aldofuranoses 2, 3 and 4, and aldopyranose 5.
Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins
Authors: Rodighiero P. , Pastorini G. , Chilin A. , Marotto A.
Published: March 2009

New linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7‐mercaptocoumarin, which were condensed with chloro‐ketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins 15, 16, 17, 18, 22, 23, 24, 27 and thiopyranocoumarins 28 and 29.
Heterocyclic and acyclic azadiene diels‐alder reactions: Total synthesis of nothapodytine B
Authors: Boger Dale L.
Published: March 2009

A summary of the applications of the inverse electron demand Diels‐Alder reactions of heterocyclic and acyclic azadienes in the total synthesis of natural products is provided and a recent application in the total synthesis of nothapodytine B (mappicine ketone) is presented in detail.
Retro‐Ene reaction. VI. Functionalization of 4,5‐dihalopyridazin‐6‐ones using 1‐acetyloxymethyl‐4,5‐dihalopyridazin‐6‐ones as the 1‐O, 3‐N, 5‐O ene‐adduct
Authors: Chung Hyun‐A , Kang Young‐Jin , Kweon Deok‐Heon , Yoon Yong‐Jin
Published: March 2009

Functionalization of 1‐acetyloxymethyl‐4,5‐dihalopyridazin‐6‐ones via retro‐ene reaction with some nucleophiles gave regioselectively only 5‐halo‐4‐substitutedpyridazin‐6‐ones.
Synthesis and reactions of 4‐Hydroxy‐2(1H)‐pyridones with thienyl and pyridyl substituents in position 6 starting with azomethines and malonates
Authors: Schnell Barbara
Published: March 2009

The reaction of 4 with substituted diethyl malonates 5a, or “magic malonates” (bis‐2,4,6‐trichlorophenylmalonates 5b) leads to 4‐hydroxy‐2(1H)‐pyridones 6. The azomethines 4 are prepared via the Strecker compounds 3 starting with methyl ketones 1, anilines, and potassium cyanide. Chlorination of pyridones 6 with sulfuryl chloride leads to compounds 7 while nitration gives 9.
An improved synthetic approach to thieno[2,3‐d]‐1,2,3‐thiadiazolecarboxylates via diazotization of aminothiophene derivatives
Authors: Stanetty Peter , Görner Erwin , Mihovilovic Marko D.
Published: March 2009

The common synthetic method for the synthesis of fused 1,2,3‐thiadiazoles via diazotization is not generally applicable to aminothiophenes. A substantially improved experimental protocol for the preparation of the title compounds as a potential inducer of systemic acquired resistance in plants is reported based on a novel cyclization mechanism via a Huisgen‐White type rearrangement.
Ring transformations of heterocyclic compounds. XVII, 2‐(2,4,6‐Triarylphenyl) substituted dihydro‐1H‐imidazolium, dihydrothiazolium and thiazolium salts from 2‐methyl derivatives by pyrylium and thiopyrylium ring transformations
Authors: Zimmermann Thomas
Published: March 2009

The synthesis of hitherto unknown 2‐(2,4,6‐triarylphenyl) substituted 4,5‐dihydro‐1H‐imidazolium perchlorates 6, 4,5‐dihydrothiazolium perchlorates 8 and thiazolium perchlorates 9 from their 2‐methyl derivatives 2, 4 and 5, respectively, by a 2,6‐[C5+C] ring transformation of 2,4,6‐triarylpyrylium and ‐thiopyrylium salts 1/10 in ethanol in the presence of an appropriate base (6: sodium ethanolate; 8,9: anhydrous sodium acetate) is reported. Spectroscopic data of the transformation products and structural influences on their formation via anhydrobases of the salts 2, 4 and 5 are discussed.
Facile synthesis of furobenzothiazepines
Authors: Ogawa Masayuki , Koyanagi Jyunichi , Sakuma Katsuya , Tanaka Akira , Yamamoto Katsumi
Published: March 2009

The reaction of methyl 5‐(2‐isocyanatophenylthio)‐2‐furancarboxylate 2 with N‐methylpiperazine gave 5‐(2‐N‐piperazinocarbamoylphenylthio)‐2‐furancarboxylate 3a. Furthermore, 4‐N‐methylpiperazinyl‐2‐methoxycarbonylfuro[2,3‐b][1,5]benzothiazepine 4a was obtained by the Bischler‐Napieralski reaction of 3a with phosphorus oxychloride in the present of phosphorus pentoxide. Three furobenzothiazepines could be obtained using the same method. Based on the pharmacological studies of these compounds, it was found that 4‐morpholinyl‐2‐methoxycarbonylfuro[2,3‐b][1,5]benzothiazepine 4b had anti‐inflammatory activity similar to flufenamic acid.
Synthesis and X‐ray structure of a novel 1,2,4‐trithiolane
Authors: Bryce Martin R. , Lay Alexander K. , Batsanov Andrei S. , Howard Judith A. K.
Published: March 2009

Photolysis of 1,2‐dithiole‐3‐thione derivative 1 results in the formation of the 1,2,4‐trithiolane derivative 2, the structure of which was established by single crystal X‐ray analysis. Interesting bond delocalisation is observed in the molecular structure. A mechanism involving dimerisation of 1 followed by loss of sulfur is proposed.
Synthesis of 5‐chloro‐2‐methyl‐3‐(5‐methylthiazol‐2‐yl)‐4(3H)‐quinazolinone and related compounds with potential biological activity
Authors: Párkányi Cyril , Schmidt Duran S.
Published: March 2009

Eight new 2‐methyl‐4(3H)‐quinazolinones (8a‐8d, 9c, 9d, 10c, 10d) with one or two chlorine atoms in the benzene ring and a 5‐methyl‐1,3‐thiazol‐2‐yl, 4‐methyl‐1,3‐thiazol‐2‐yl, and 5‐ethyl‐1,3,4‐thiadiazol‐2‐yl substituent in position 3 of the heterocyclic ring were synthesized and characterized. The two step procedure (Scheme 1) utilizes chlorosubstituted anthranilic acids (3a‐3d) and acetic anhydride as the starting materials, with the respective chlorosubstituted 2‐methyl‐4H‐3,1‐benzoxazin‐4‐ones (4a‐4d) as the intermediates. The quinazoline derivatives were characterized by their melting points, elemental analyses and the mass, ultraviolet, infrared, and 1H and 13C nmr spectra. The new compounds are expected to be biologically active.
Ring enlargement reactions of tetramic acid derivatives
Authors: Poschenrieder Hermann , Eckl Eduard , Stachel Hans‐Dietrich , Windt Andreas , Polborn Kurt
Published: March 2009

The 4‐hydroxypyridones7and 3‐hydroxypyridones8/9(azagrevellins) were prepared by reaction of the pyrrolidinetrione4and diazoalkanes. The ring enlargement proceeded by anionotropic [1,2]‐rearrangement introducing carbon between C‐3 and C‐4 or, to a lesser extent, between C‐2 and C‐3 due to the different migration aptitudes of the two acyl groups involved. In a cognate manner ring expansion between C‐2 and C‐3 occured by the interaction of diazomethane and the pyrrolidinetrione hydrazone15, to give the spiroe‐poxide16as the final product. From the reaction of trione4and diazomethane, however, the diepoxide14was obtained. In this case ring homologation must have taken place by insertion of carbon between C‐4 and C‐5. In a two step ring expansion the pyridones21and22were obtained from the maleineimides17.
Conformational properties of thiophene oligomers
Authors: Millefiori Salvatore , Alparone Andrea , Millefiori Arcangelo
Published: March 2009

The molecular geometries and the torsional potentials about the inter‐ring C‐C bond in α‐oligothiophenes (α‐nTh, n=2–4) have been calculated by means of conventional ab initio and density functional theory (DFT) calculations employing the hybrid B3LYP and BH&HLYP functionals. The position and the energetics of the critical points in the potential energy curve generated by rotation about the inter‐ring CC bond are shown to be dependent on the computational method. DFT calculations, in comparison with MP2 calculations, favour conjugative interactions, while steric and coulombic interactions are equally treated by both methods. On oligomerization the electron delocalisation increases slightly, the p‐charge being preferentially confined within the rings, although it is sufficient to move the molecular structure towards co‐planarization and to increase the barrier through the perpendicular conformation. The IR and Raman spectra on the relevant rotamers of α‐2Th have been computed at HF/6–31G* and B3LYP/6–31G* levels. The comparison with the experiment is excellent. It has been found that small twisting from the planar conformation has no apparent effects, while 90° twisting and isomerization to the syn‐gauche form produce significant frequency and intensity variations which could be useful probes in conformational studies. The simulated IR and Raman spectra of the α‐2Th rotamers are consistent with a smallπ‐electron delocalisation between the rings.
Ab initio study of azolides: Energetic and spectroscopic properties
Authors: Claramunt Rosa MarÍA , Sanz Dionisia , Alkorta Ibon , Elguero JosÉ , Foces‐Foces ConceptiÓN , Llamas‐Saiz Antonio L.
Published: March 2009

We report the ab initio study of twenty‐four azolides derived from pyrrole, imidazole, pyrazole, both triazoles, tetrazole, pentazole, indole and carbazole bearing at the nitrogen atom the groups COMe, CHO, COCF3 and CO2Me. Theoretical values (isomerism, barriers, dipole moments, C=O stretching) are compared with experimental ones, when available, and also internally compared. A special effort has been devoted to the calculation of the absolute shieldings for the different nuclei present in azolides. At the level of calculation used (RHF/6‐311G**) the results are satisfactory. To complete the nmr data from the literature, some 1H, 13C, 15N, 17O and 19F chemical shifts have been determined.
The synthesis and nucleophilic substitution of haloxanthones
Authors: Sharghi Hashem , Tamaddon Fatemeh
Published: March 2009

Acylation reaction of m‐cresol with 2,6‐dihalobenzoic acid in the presence of methansulfonic acid and subsequently, cyclization of the obtained o‐hydroxybenzophenones with K2CO3/dimethyl formamide, afforded haloxanthones 4 and 5 in high yields. Aromatic nucleophilic substitution of the resulted haloxanthones with O‐, N‐ and S‐nucleophiles are studied in a comparative manner, and various new O‐, N‐ and S‐substituted xanthones have obtained.
Studies with enaminones: synthesis of new coumarin‐3‐yl azoles, coumarin‐3‐yl azines, coumarin‐3‐yl azoloazines, coumarin‐3‐yl pyrone and coumarin‐2‐yl benzo[b]Furans
Authors: El‐Taweel Fathy Mohamed Abel Aziz , Elnagdi Mohamed Hilmy
Published: March 2009

3‐Acetylcoumarine was condensed with dimethylformamide dimethylacetal (DMFDMA) to yield the enaminone, which reacts readily with hydroxylamine and with hydrazines to yield coumarin‐3‐ylisoxazoles and coumarin‐3‐ylpyrazoles respectively. Reaction of the enaminone with benzamidine hydrochloride and 3‐amino‐1,2,4‐1H‐triazole affords the pyrimidine and triazolo[3,4‐b]pyrimidine. The enaminone reacts with hippuric acid and with the dithiocarboxylic acid to yield pyranones. The reaction of the enaminone with 3‐amino‐1H‐1,2,4‐triazole gives the triazolo[3,4‐b]pyrimidine. The enaminone underwent self dimerization on reflux in acetic acid ammonium acetate to yield the coumarinyl pyridines and reacted with ketone under the same conditions to yield the pyridine. The reaction of the enaminone with 1,4‐benzoquinone and 1,4‐naphthoquinone gives benzofuryl coumarine derivatives.
Synthesis of polycyclic nitrogen‐containing heterocyclic: One pot formation of 1,6‐naphthyridine ring system by reaction of amino‐cyano‐methylthio‐heterocycles with dialkyl acetyeledicarboxylates
Authors: Tominaga Yoshinori , Nomoto Kenichi , Yoshioka Noriko
Published: March 2009

Reaction of 3‐amino‐3‐methylthio‐2‐cyanoacrylonitrile (1) with excess dimethyl acetylenedi‐carboxylate(DMAD) in the presence of potassium carbonate in dimethyl sulfoxide gave a novel tricyclic heterocycle, hexamethyl lH‐1,4,7‐triazaphenalene‐2,3,5,6,8,9‐hexacarboxylate (5a). When one equivalent of DMAD was used in this reaction, dimethyl 4‐amino‐3‐cyano‐2‐methylthiopyridine‐5,6‐dicarboxylate (3a), a key intermediate of5a, was obtained.
A short synthesis of 5,7‐bis(dialkylamino)‐2‐methyl‐ 8 ‐hydroxyquinolines
Authors: Okide George B.
Published: March 2009

The bromine atoms of the title compound were replaced by the requisite amino compound to afford the desired derivatives in high yields. Thus, six target compounds viz‐ bis(diethylamino)‐, bis(dibutylamino)‐, bis(dicyclohexylamino)‐, dipyrrolidino‐, dipiperidino‐, and dipiperazino‐derivatives were obtained and characterized by spectral and elemental analyses.
Synthesis and application of 2‐styryl‐6,7‐dichlorothiazolo[4,5‐b]‐quinoxaline based fluorescent dyes: Part 3
Authors: Sonawane N. D. , Rangnekar D. W.
Published: March 2009

A new efficient synthesis of 2‐styryl‐6,7‐dichlorothiazolo[4,5‐b]quinoxaline based fluorescent dyes was achieved by the condensation of 2‐methyl‐6,7‐dichlorothiazolo[4,5‐b]quinoxaline with selected 4‐N,N‐dialkylaminoarylaldehydes and heteroarylaldehydes in the presence of piperidine. The coloristic, fluo‐rophoric, and dyeing properties of these dyes were studied.
Synthesis of imidazoles as novel emivirine and S‐DABO analogues
Authors: Loksha Yasser M. , Jørgensen Per T. , Pedersen Erik B. , El‐Badawi Mahmoud A. , El‐Barbary Ahmed A. , Nielsen Claus
Published: March 2009

5‐Alkyl‐4‐benzyl‐1,3‐dihydroimidazol‐2‐ones (3a‐d) and 5‐alkyl‐4‐benzyl‐1,3‐dihydroimidazole‐2‐thiones (7a‐d) were prepared via Dakin West reaction on DL‐phenylalanine with the appropriate aliphatic acid anhydrides followed by hydrolysis and reaction with potassium cyanate or potassium thiocyanate. Compounds 3a‐d were alkylated with ethoxymethyl chloride to give the alkylated imidazoles 5a‐d which were considered analogues of Emivirine with deletion of carbonyl group at the 4‐position. Alkylation of 7a‐d afforded the corresponding S‐alkylated derivatives 8a‐p which in a similar way were considered analogues of S‐DABO. However all the imidazole derivatives were devoid of activity against HIV.
Research on heterocyclic compounds. XLIII. Synthetic studies on 1,4‐dihydropyridine derivatives
Authors: Rimoli Maria Grazia , Avallone Lucia , Zanarone Serena , Abignente Enrico , Mangoni Alfonso
Published: March 2009

In order to obtain N‐benzyl‐3,5‐dicarbethoxy‐2,6‐dimethyl‐4‐phenyl‐1,4‐dihydropyridine 1 as a lead compound of pharmacological interest, the classical Hantzsch synthetic method and the modified Collie procedure were used. However, only a very low yield of 1 was obtained in a mixture with larger amounts of some by‐products (2, 3, 4). Compound 1 was then synthesized in satisfactory yield via a different method, together with another by‐product (9). The structures of all by‐products were elucidated and possible mechanisms leading to the formation of such compounds are described.
A convenient synthesis of 2‐Arylidene‐5H‐thiazolo[2,3‐b]quinazo‐line‐3,5[2H]‐diones and their benzoquinazoline derivatives
Authors: Khodair Ahmed I.
Published: March 2009

Various 5H‐thiazolo[2,3‐b]quinazoline‐3,5[2H]‐diones (7a,b), 2‐arylidene‐5H‐thiazolo[2,3–b]quin‐azoline‐3,5[2H]‐diones (9a‐o) and 2‐arylidene‐5H‐thiazolo[2,3‐b]benzoquinazoline‐3,5[2H]‐diones (12a,b) have been synthesized via simple and efficient methods.
Synthesis and reactions of 11H‐benzo[b]pyrano[3,2‐f]indolizines an pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolines
Authors: Kappe Thomas , Roschger Peter , Schuiki Birgit , Stadlbauer Wolfgang
Published: March 2009

2‐Methyl‐3H‐indoles 1 cyclize with two equivalents of ethyl malonate 2 to form 4‐hydroxy‐11H‐benzo[b]pyrano[3,2‐f]indolizin‐2,5‐diones 3, whereas 2‐mefhyl‐2,3‐dihydro‐1H‐indoles 9 give under similar conditions regioisomer 8‐hydroxy‐5‐methyl‐4,5‐dihydro‐pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolin‐7,10‐diones 10. The pyrone rings of 3 and 9 can be cleaved either by alkaline hydrolysis to give 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 4 or 5‐acetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo‐[3,2,1‐ij]quinolin‐4‐ones 11, respectively. Chlorination of 3 and 9 with sulfurylchloride gives under subsequent ring opening 7‐dichloroacetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 5 or 5‐dichloracetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 12. The dichloroacetyl group of 5 can be reduced with zinc to 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 7. Treatment of the acetyl compounds 4, 7 and 11 with 90% sulfuric acid cleaves the acetyl group and yields 8‐hydroxy‐10H‐pyrido[1,2‐a]‐indol‐6‐ones 6 and 8, and 6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 13. Reaction of dichloroacetyl compounds 12 with sodium azide yields 6‐hydroxy‐2‐methyl‐5‐(1H‐tetrazol‐5‐ylcarbonyl)‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 14 via intermediate geminal diazides.
An efficient synthesis of 3,5‐dimethoxyhomophthalic acid, a key intermediate for synthesis of natural isocoumarins
Authors: Saeed Aamer , Rama Nasim H. , Arfan M.
Published: March 2009

3,5‐Dimethoxyhomophthalic acid was prepared efficiently in three steps, from 3,5‐dimethoxybenzyl bromideviarhodium‐catalyzed direct carbonylation to 3,5‐dimethoxyphenylacetic acid followed by successiveo‐formylation and oxidation. Isocoumarins related to agrimonolide and achlisocoumarin 1 were prepared in single step by condensation of the homophthalic acid with appropriate acid chlorides.
Synthesis of acrimarins from 1,3,5‐trioxygenated‐9‐acridone derivatives
Authors: Herath H. M. T. B. , Müller K. , Diyabalanage H. V. K.
Published: March 2009

1,3,5‐Trihydroxy‐9(10H)‐acridinone (1) was prepared from 3‐hydroxyanthranillic acid with phloroglucinol. 1,3‐Dihydroxy‐5‐methoxy‐9(10H)‐acridinone (2) was prepared from 3‐methoxyanthranillic acid and phloroglucinol. Methylation of 1 under different conditions gave 1‐hydroxy‐3,5‐dimethoxy (3), 1‐hydroxy‐3,5‐dimethoxy‐10‐methyl (4), 1‐hydroxy‐3,5‐dimethoxy‐4‐methyl (5), 1,3,5‐trimethoxy‐10‐methyl (6) and 1,3,5‐trimethoxy‐4,10‐dimethyl (7) analogues. Demethylation of 4 afforded the 1,3,5‐trihydroxy‐10‐methyl analogue 8. Condensation of acridones 1, 2, 3 and 4 individually with E‐suberenol (9) gave four novel acrimarins (acridone‐coumarin dimers) 10, 11, 12 and 13 respectively, while the acridone 8 gave previously reported acrimarin‐G (14).
Synthesis of original benzo[g]quinoxaline‐5,10‐diones by bis‐SRN1 methodology
Authors: Remusat Vincent , Terme Thierry , Gellis Armand , Rathelot Pascal , Vanelle Patrice
Published: March 2009

A new heterocyclic bioreductive bis‐alkylating agent, 2,3‐bis(chloromethyl)benzo[g]quinoxaline‐5,10‐dione, was prepared in a four‐steps synthesis. It was shown to react under electron transfer conditions with 2‐nitropropane anion by an bis‐SRN1 mechanism to give three C‐alkylation products in excellent yields. Extension of this bis‐SRN1 reaction to various nitronate or malonate anions and S‐centered anions led to a new class of potentially active benzo[g]quinoxaline‐5,10‐dione derivatives.
Water‐soluble pH‐sensitive 2,6‐bis(substituted ethylidene)‐cyclohexanone/hydroxy cyanine dyes that absorb in the visible/near‐infrared regions
Authors: Strekowski Lucjan , Mason J. Christian , Lee Hyeran , Say Martial , Patonay Gabor
Published: March 2009

Three methods were used to synthesize a series of the title compounds. The ketones absorb in the visible region, and upon protonation (pH<6) they are converted to hydroxy‐substituted heptamethine cyanines that show an intense absorption in the near‐infrared region (>700 nm). The conversion is reversible and depends solely on pH conditions.
Synthesis and fluorescent properties of 2‐(1H‐benzimidazol‐2‐yl)‐phenol derivatives
Authors: Ouyang Jie , Ouyang Chenguang , Fujii Yuki , Nakano Yoshiharu , Shoda Takuji , Nagano Tetsuo
Published: March 2009

A high yield one pot synthesis of 2‐(2‐hydroxyaryl)‐1H‐benzirrndazole derivatives by 2‐hydroxy aromatic aldehydes with aromatic 1,2‐diamines in the presence of manganese(III) acetate at room temperature was developed. Nine fluorescencers 2‐(2‐hydroxyaryl)‐1H‐benzirrndazoles with substituent(s) X (X = H, CH3, CH3O, Cl) and two fluorescencers 2‐(2‐hydroxyaryl)‐1H‐naphth[2,3‐d]imidazoles with substituent of H or Cl were prepared in 38–87% yield and the ultraviolet absorption and fluorescent spectra of the eleven compounds synthesized were measured in methanol. The fluorescent characteristics of the 2‐(2‐hydroxyaryl)benzimidazole derivatives prepared were investigated on the basis of excited‐state intramolecular proton transfer mechanism, Stokes' shift, quantum yield, and the relationship between fluorescent intensity and the substituents were derived.