bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐dimensional NMR studies of marine natural products. IV. Isolation of the cembranoid diterpene jeunicin from the mollusc planaxis sulcatus: Assignment of the proton and carbon NMR spectra by two‐dimensional techniques
Authors: Sanduja Radhika , Linz Gary S. , Alam Maktoob , Weinheimer Alfred J. , Martin Gary E. , Ezell Edward L.
Published: March 2009

Numerous cembranoic diterpenes have been isolated from marine gorgonians and terrestrial plants. There have, however, been only a few reports of the isolation and identification of these interesting compounds from higher animal sources. The isolation of the oxo‐bridged cembranoid diterpene jeunicin from the mollusc Planaxis sulcatus is reported. A comparative discussion of the utility of COSY, homonuclear RELAY (relayed COSY) and proton double quantum coherence techniques is presented, the latter successfully establishing the identities of all of the proton resonances. Acquisition of a two‐dimensional proton‐carbon chemical shift correlation spectrum provided the means of unequivocally establishing 13C resonance assignments.
Synthesis of 1H‐imidazo[1,2‐a]imidazole
Authors: Compernolle Frans , Toppet Suzanne
Published: March 2009

The synthesis and structure analysis of the unknown 1H‐imidazo[1,2‐a]imidazole (1) is described. The preparation involves alkylation of 2‐aminoimidazole with bromoacetaldehyde diethyl acetal and subsequent hydrolysis and cyclization with hydrochloric acid. The structure was characterized by mass spectrometry and by 1H‐, 15N‐ and 13C‐nmr of 1 and by 1H‐nmr of its 1‐benzyl derivative 8. An independent synthesis of 8 was accomplished via cyclization of 2‐(N‐dichloroethyl‐N‐benzyl)aminoimidazole (11).
Products from furans. VI. Synthesis of dihydro‐2‐disubstituted‐2H‐pyran‐3(4H)‐ones, tetrahydro‐3‐(aminomethyl)‐2‐(p‐methoxyphenyl)‐2‐methyl‐2H‐pyran‐3‐ol derivatives and 6‐(p‐methoxyphenyl ‐6‐methyl‐7‐oxa‐1,3‐diazaspiro[4,5]decane‐2,4‐dione
Authors: Georgiadis Minas P.
Published: March 2009

Hydrogenolysis of 5,6‐dihydro‐6‐(p‐methoxyphenyl)‐6‐methyl‐5‐oxo‐2H‐pyran‐2‐yl ethyl carbonate yielded dihydro‐2‐(p‐methoxyphenyl)‐2‐methyl‐2H‐pyran‐3(4H)‐one, 3. Subsequently cyanohydrin 4, derived from 3, on reduction afforded 3‐(aminomethyl)tetrahydro‐2‐(p‐methoxyphenyl)‐2‐methyl‐2H‐pyran‐3‐ol, 5. The synthesis of N‐dimethyl,N‐isopropyl,N‐imidazolyl as well as N‐oxazolinyl derivatives of 5 is presented. The synthesis of 6‐(p‐methoxyphenyl)‐6‐methyl‐7‐oxa‐1,3‐diazaspiro[4,5]decane‐2,4‐dione 10, a spiro hydantoin prepared from ketone 3 is also reported.
A new synthesis of novel 1‐aryl‐3‐heteroaryl‐1H‐pyrazolo[3,4‐b]quinoxalines via a Key Intermediate
Authors: Kurasawa Yoshihisa , Muramatsu Muneto , Yamazaki Kaoru , Tajima Setsuko , Okamoto Yoshihisa , Takada Atsushi
Published: March 2009

The chlorination of the α‐hydrazonoester 4 with phosphoryl chloride/pyridine gave 3‐[α‐(o‐chlorophenylhydrazono)methoxycarbonylmethyl]‐2‐chloroquinoxaline 5, whose cyclization with 1,8‐diazabicyclo[5,4,0]‐7‐undecene afforded 3‐methoxycarbonyl‐1‐(o‐chlorophenyl)‐1H‐pyrazolo[3,4‐b]quinoxaline 6. The reaction of 6 with hydrazine hydrate provided 3‐hydrazinocarbonyl‐1‐(o‐chlorophenyl)‐1H‐pyrazolo[3,4‐b]quinoxaline 7, whose reactions with methyl and allyl isothiocyanates furnished 3‐(2,3‐dihydro‐4‐methyl‐3‐thioxo‐4H‐1,2,4‐triazol‐5‐yl)‐1‐(o‐chlorophenyl)‐1H‐pyrazolo[3,4‐b]quinoxaline 2 and 3‐(4‐allyl‐2,3‐dihydro‐3‐thioxo‐4H‐1,2,4‐triazol‐5‐yl)‐1‐(o‐chloropheny)‐1H‐pyrazolo[3,4‐b]quinoxaline 8, respectively. Moreover, the reactions of 7 with triethyl orthoformate and orthoacetate gave 1‐(o‐chlorophenyl)‐3‐(1,3,4‐oxadiazol‐5‐yl)‐1H‐pyrazolo‐[3,4‐b]quinoxaline 9a and 1(o‐chlorophenyl)‐3‐(2‐methyl‐1,3,4‐oxadiazol‐5‐yl)‐1H‐pyrazolo[3,4‐b]quinoxaline 9b, respectively.
Synthesis of novel 3‐(α‐arylhydrazono‐1,3,4‐oxadiazol‐2‐ylmethyl)‐2‐oxo‐1,2‐dihydroquinoxalines and their characteristic tautomerism between the hydrazone imine and diazenyl enamine forms
Authors: Kurasawa Yoshihisa , Muramatsu Muneto , Okamoto Yoshihisa , Takada Atsushi
Published: March 2009

The reactions of 3‐(α‐arylhydrazono)hydrazinocarbonylmethyl‐2‐oxo‐1,2‐dihydroquinoxalines 1a,b with triethyl orthoesters resulted in the intramolecular cyclization to give the 3‐(α‐arylhydrazono‐1,3,4‐oxadiazol‐2‐ylmethyl)‐2‐oxo‐1,2‐dihydroquinoxalines 4a–d, but not the 1,2,4,5‐tetrazepinylquinoxalines 5a–d. The cyclization mode into the 1,3,4‐oxadiazole ring was confirmed by the alternate syntheses of 4a,c from the reactions of 3‐(1,3,4‐oxadiazol‐2‐ylmethylene)‐2‐oxo‐1,2,3,4‐tetrahydroquinoxalines 6a,b with o‐chlorophenyl diazonium salts, respectively. Moreover, 4a–d exhibited an interesting tautomerism between the hydrazone imine form A and diazenyl enamine form B.
A comparative study on the synthesis of the 1H[1]benzothieno[2,3‐d]‐imidazole and 1H[1]benzothieno[2,3‐d]‐v‐triazole
Authors: Guerrera Francesco , Siracusa Maria Angela , Santagati Natale Alfredo , Tornetta Benedetto
Published: March 2009

Alternate routes for the synthesis of the new title compounds are described. The experimental procedure for the isolation of the unstable 2,3‐diaminobenzo[b]thiophene as the dichloride salt is presented.
Obtention de dialkylamino‐2 cyano‐3 2H‐chromènes
Authors: Auzou Gilles , René Loïc
Published: March 2009

Les dialkylamino‐2 cyano‐3 chromènes‐2H sont obtenus en un seul stade par condensation de β‐cyanoenamines et d'aldéhydes salicyliques substitués ou non, en présence d'acide para toluéne sulfonique.
A new method for the synthesis of novel 1‐aryl‐3‐heteroaryl‐1H‐pyrazolo[3,4‐b]quinoxalines
Authors: Kurasawa Yoshihisa , Muramatsu Muneto , Yamazaki Kaoru , Tajima Setsuko , Okamoto Yoshihisa , Takada Atsushi
Published: March 2009

The reaction of 3‐(2,3‐dihydro‐4‐methyl‐3‐thioxo‐4H‐1,2,4‐triazol‐5‐ylmethylene)‐2‐oxo‐1,2,3,4‐tetrahydroquinoxaline 4 with o‐chlorobenzenediazonium chloride gave 3‐[α‐(o‐chlorophenylhydrazono)‐2,3‐dihydro‐4‐methyl‐3‐thioxo‐4H‐1,2,4‐triazol‐5‐ylmethyl]‐2‐oxo‐1,2‐dihydroquinoxaline 6, whose refluxing in phosphoryl chloride/pyridine afforded 1‐(o‐chlorophenyl)‐3‐(2,3‐dihydro‐4‐methyl‐3‐thioxo‐4H‐1,2,4‐triazol‐5‐yl)‐1H‐pyrazolo[3,4‐b]quinoxaline 7. The reactions of 6 and 7 with nitrous acid resulted in sulfur extrusion to provide 1‐(o‐chlorophenyl)‐3‐(4‐methyl‐4H‐1,2,4‐triazol‐5‐yl)1H‐pyrazolo[3,4‐b]quinoxaline 8 and 3‐[α‐(o‐chlorophenylhydrazono)‐4‐methyl‐4H‐1,2,4‐triazol‐5‐ylraethyl]‐2‐oxo‐1,2‐dihydroquinoxaline 9, respectively.
3‐[(Z)‐2‐t‐Butoxyethenyl]‐4‐hydroxy‐2(5H)‐furanone, an interesting byproduct obtained from reaction of 4‐t‐butoxy‐2‐butenoate with the alkoxide anion of methyl glycolate
Authors: Arora S. K. , Cho B. S. , Chadha V. K. , Bauer A. J. , Venton D. L. , Lim C. T. , Le Breton G. C.
Published: March 2009

Treatment of methyl 4‐t‐butoxy‐2‐butenoate (1) with the alkoxide anion of methyl glycolate gives, in addition to the previously reported (Fried, et al. [2]) 2,3‐disubstítuted‐2,3‐dihydro‐4‐furanone 2, an equivalent amount of the interestingly substituted 3‐[(Z)‐2‐t‐butoxyethenyl]‐4‐hydroxy‐2(5H)furanone 3. Isolation, structure proof and possible mechanism of formation are presented
Formation and molecular structure of the novel acridine substituted uracil derivatiLves
Authors: Kimura Michio , Okabayashi Ichizo
Published: March 2009

The reaction of enamine between 9‐chloroacridines and 6‐aminouracil derivatives gives the novel acridine substituted uracils, the structure of which has been determined by X‐ray crystallography.
Synthesis of imidazo[1,5‐c]pyrimidine derivatives
Authors: Wade James J.
Published: March 2009

Two complementary procedures, each starting from 6‐aminomethyluracil (2), have been used to prepare imidazo[1,5‐c]pyrimidines with a variety of substituents at positions 3, 5, 6, and 7. The starting material,2, can be readily prepared from commercially available 6‐chloromethyluracil by reaction with anhydrous ammonia. In the first procedure,2is acylated and then cyclodehydrated by reaction with phosphorus oxychloride to give a separable mixture of a 3‐substituted 5,7‐dichloroimidazo[1,5‐c]pyrimidine and a 3‐substituted 7‐chloroimidazo[1,5‐c]pyrimidin‐5(6H)‐one. The relative product distribution is subject to some control by the choice of the acyl substituent on the starting uracil. The resulting dichloro compounds were derivatized by reaction at the 5‐position with various nucleophiles, although the 7‐chloro substituent is unreactive. An alternative synthetic method proceeds from2in six efficient steps (protection as the phthalimide, chlorination, nucleophilic substitution, deprotection, acylation, and cyclodehydration) to 3‐substituted‐5,7‐bis(methylthio)imidazo[1,5‐c]pyrimidines. These compounds may also be derivatized by nucleophilic substitution at the 5‐position.
Synthesis and reactions of an open‐chain bis‐reissert salt analog
Authors: Iyer Radhakrishnan P. , Ratnam Rakesh K. , Kulkarni Subodh P. , Sonaseth Mariam S.
Published: March 2009

An open‐chain bis‐Reissert salt analog 5 has been synthesized and fully characterized. The reaction of the salt analog with methyl acrylate yields the pyrrole 7 which exists in solution in the azafulvene form 7a. The reaction of the salt analog with dimethylacetylene dicarboxylate (DMAD) affords the bispyrrole 9.
Reaction of o‐aminophenol and p‐benzoquinone in acetic acid
Authors: Bolognese Adele , Scherillo Giulia , Schäfer Wolfram
Published: March 2009

The reaction of o‐aminophenol and p‐benzoquinone in acetic acid yields phenoxazinones 1, 5 and 6, phenoxazine 7, triphenodioxazine 2, ditriphenodioxazine 3 and the phenoxazinonyltriphenodioxazine 4.
1‐Azadienes in heterocyclic synthesis. Reaction of 1‐N‐alkyl‐1‐azapenta‐1,3‐dienes with mesoionic oxazolones
Authors: Sain B. , Sandhu J. S.
Published: March 2009

1‐N‐Alkyl‐1‐azapenta‐1,3‐dienes 2 smoothly reacted with various mesoionic oxazolones 1 to afford 3,4‐di‐hydro‐2‐pyridones 3 in excellent yields and there was no evidence for the formation of any products arising from the cycloaddition on the carboncarbon double bond or on the azomethine function.
Reaction of N‐(4‐pyridylmethyl)benzamide N‐oxides with ethyl cyanoacetate in the presence of acetic anhydride
Authors: Braña Miguel F. , Rodríguez María L. López , Rodríguez Concepción , Garrido‐Pertierra Amando
Published: March 2009

Reaction of N‐(4‐pyridylmethyl)benzamide N‐oxides 2a‐f with ethyl cyanoacetate in the presence of acetic anhydride yield dimerization compounds 3a‐f and (E)‐ethyl 2‐cyano‐3‐(4‐pyridyl)‐3(benzoylamino)acrylates 4a‐f, which react with hydrazine to give 4‐cyano‐3‐(4‐pyridyl)‐3‐pyrazolin‐5‐one 9 and the corresponding benzamides 10a‐f.
Adamantylazoles. 5. The molecular structure of 1‐(1‐adamantyl)pyrazoles
Authors: Cabildo P. , Claramunt R. M. , Sanz D. , Foces‐Foces M. C. , Cano F. Hernández , Fayet J. P. , Vertut M. C. , Elguero J.
Published: March 2009

The crystal structures of 1‐(1‐adamantyl)‐3,5‐dimethylpyrazole 1 and 1‐(1‐adamantyl)‐3,4,5‐trimethylpyrazole 2 were studied by X‐ray analysis. The space groups and cell parameters are: 1, Cc, 13.4452(4), 14.9407(4), 7.1119(2) Å, 90, 111.944(2), 90°, with Z = 4. 2, P21/c, 6.7466(1), 21.2565(7), 10.1462(2) Å, 90, 106.368(2), 90°, with Z = 4. The final disagreement factors were 0.069 and 0.061, for 721 [2σ(I)] and 1950 [2σ(I)] observed reflexions, respectively. Compound 1 presents the adamantyl residue disordered between the two usual conformations. The experimental dipole moments and the carbon‐13 chemical shifts (both in hexadeuteriodi‐methylsulfoxide and in the solid state) were measured and discussed in connection with the structure of these compounds.
Novel synthesis of pyrido[1,2‐a]benzimidazoles via reaction of N‐acyl arylhydroxylamines with pyridine
Authors: Anderson David J. , Taylor Arlen J.
Published: March 2009

The reduction of 4‐chloro‐3,5‐dinitrobenzonitrile via catalytic hydrogenation and/or titanium trichloride produced three successive hydroxylamines 6,7, and 8 that were fully characterized during complete reduction to the diamine 9. The nitrohydroxylamine 6 was acetylated to the mono‐N‐acetyl and bis‐acetyl derivatives 10 and 11 which reacted with pyridine to afford the pyrido[1,2‐a]benzimidazole 13. An analoguous series of reactions was executed with 4‐chloro‐3,5‐dinitrobenzotrifluoride to afford the pyrido[1,2‐a]benzimidazole 21. Structure confirmation of 21 was established via an x‐ray determination. The mechanism of the transformation is discussed.
Synthesis of 2‐substituted benzimidazole‐5‐carbamates as potential antifilarial agents
Authors: Ram Siya , Wise Dean S. , Townsend LeRoy B.
Published: March 2009

A number of 2,5‐disubstituted benzimidazoles have been prepared from 2‐benzyl‐5‐nitrobenzimidazole (5) and 2‐p‐fluorobenzyl‐5‐nitrobenzimidazole (6), and evaluated as potential antifilarial agents. None of the compounds prepared in this study have demonstrated any significant antifilarial activity.
The crystal and molecular structure of 9‐methylphenanthro[4,3‐a]dibenzothiophene
Authors: Quast Michael J. , Martin Gary E. , Lynch Vincent M. , Simonsen Stanley H. , Stuart John G. , Tedjamulia Marvin L. , Castle Raymond N. , Lee Milton L.
Published: March 2009

The crystal structure of 9‐methylphenanthro[4,3‐a]dibenzothiophene, C25H16S, Mr = 348.47, has been determined. Monoclinic, P21/c, a = 11.364(3), b, = 14.257(3), c = 11.575(2)Å, β = 116.26(2)°, V = 1681.9(7)Å3, Z = 4, Dx = 1.38 g/cc, MoKα radiation λ = .71069 Å, F(000) = 728, T = 163K, R = .0458 for 2330 reflections. The structure compares favorably with that of hexahelicene and methylated derivatives. The thiophene moiety increases the helical core radius and decreases the pitch with respect to hexahelicene and its derivatives.
Mass spectral fragmentation pattern of 3‐methyl‐ and 3‐phenyl‐4‐(N‐methylarylhydrazono)isoxazol‐5‐ones
Authors: Keats Neil G. , Singh Shyam K. , Summers Lindsay A.
Published: March 2009

3‐Methyl‐4‐(N‐methylarylhydrazono)isoxazol‐5‐ones and 3‐phenyl‐4‐(N‐methylarylhydrazono)isoxazol‐5‐ones undergo considerable fragmentation on electron impact involving rupture of the isoxazolone ring and bonds in the N‐methylarylhydrazono side chain.
Studies on furan derivatives. XIV. Nucleophilic substitution of methyl 5‐nitro‐2‐furancarboxylate and 5‐Nitrofuran‐2‐nitrile
Authors: Shimadzu Masaji , Ishikawa Nobuko , Yamamoto Katsumi , Tanaka Akira
Published: March 2009

Methyl 5‐alkoxy‐2‐furancarboxylates, methyl 5‐alkylthio‐2‐furancarboxylates and methyl 5‐phenylthio‐2‐furancarboxylate were prepared by nucleophilic substitution of methyl 5‐nitro‐2‐furancarboxylates. Also, 5‐phenoxyfuran‐2‐nitriles and 5‐phenylthiofuran‐2‐nitriles were prepared.
Preparation and some spectral properties of benzo‐fused 1,4‐dimethyl‐2(1H)‐quinolinones
Authors: Ito Keiichi , Maruyama Junko , Shimamori Takako
Published: March 2009

The preparation of the angular and linear isomers of benzo‐fused 1,4‐dimethyl‐2(1H)‐quinolinones 3a–5a and their spectral data including 13C‐nmr data are reported. Structural difference among 3a–5a is confirmed from the proximity effect in 1H‐ and 13C‐nmr data and from the uv spectral pattern.
Triazole phosphonates. Electrophilic substitution of 1‐substituted‐1H‐1,2,4‐triazoles via lithiated triazole intermediates
Authors: Anderson D. Keith , Sikorski James A. , Reitz David B. , Pilla Linda T.
Published: March 2009

The metalation chemistry of several 1‐substituted‐1H‐1,2,4‐triazoles has been investigated. When various alkyl groups were incorporated in the 1‐position, lithiation proceeded exclusively at C‐5. The 1‐trityl‐, 1‐methyl‐, and 1‐benzyl‐5‐lithio‐1,2,4‐triazoles were stable at −78° and reacted cleanly with a variety of electrophiles. The 1‐benzyl and 1‐methyl derivatives were synthetically more versatile and could be successfully utilized to prepare several examples of the previously unknown 1,2,4‐triazol‐5‐yl phosphonates.
The syntheses of pteridin‐2‐one derivatives from diaminomaleonitrile (DAMN)
Authors: Tsuzuki Koichi , Tada Masaru
Published: March 2009

1,3‐Dimethyl‐4‐iminopteridin‐2‐one, 1,3‐dimethylpteridine‐2,4‐dione, 1‐methylpteridine‐2,4‐dione, 4‐alkoxy‐1‐methylpteridin‐2‐one, and 4‐alkylamino‐1‐methylpteridin‐2‐one were synthesized from diaminomaleonitrile (DAMN) through pyrazine‐2,3‐dicarbonitrile. The synthetic procedures consist of the condensation of DAMN with glyoxal, the nucleophilic substitution of pyrazine‐2,3‐dicarbonitrile with methylamine, the reaction of 3‐methylaminopyrazine‐2‐carbonitrile with electrophiles such as methyl isocyanate and methyl chloroformate in the presence of sodium hydride, and the transformation of 3‐(methoxycarbonylmethyl)aminopyrazine‐2‐carbonitrile into the pteridine derivatives.
Imino‐bridged heterocycles. VII.N‐aminobenzocycloheptapyridinimines
Authors: Brenner Daniel G. , Pitzenberger Steven M. , Shepard Kenneth L. , Varga Sandor L.
Published: March 2009

Condensation of anhydrous hydrazine with a variety of benzocycloheptapyridinones led to N‐aminobenzocycloheptapyridinimines. Regiospecific ring closures occurred in all the systems investigated.
Synthesis and in vitro antimicrobial and antifungal properties of some novel 1,3,4‐thiadiazole and s‐triazolo[3,4‐b][1,3,4]thiadiazole derivatives
Authors: Omar A.‐Mohsen M. E. , Aboulwafa Omaima M.
Published: March 2009

A novel series of 2‐arylthiocarbamoylhydrazino‐5‐phenyl‐1,3,4‐thiadiazoles III‐VII was synthesized and cyclodesulfurized into the corresponding 3‐arylamino‐6‐phenyl‐s‐triazolo[3,4‐b][1,3,4]thiadiazoles VIII‐XII with DCCD. Some of the products were found to be only moderately active against Staphylococcus aureus and Candida albicans.
Nitriles in heterocyclic synthesis. A novel synthesis of spiropyran‐4‐ylindolidene derivatives
Authors: Hafez Ebtisam Abdel Aziz , Abdul Galil Fathy M. , Sherif Sherif M. , Elnagdi Mohamed H.
Published: March 2009

The structure of the products of reaction of 2‐oxo‐3‐dicyanomethylidene‐2,3‐dihydroindole (1a) and 2‐oxo‐3‐cyanoethoxycarbonylmethylidene‐2,3‐dihydroindole (1b) with the pyrazolin‐5‐one derivatives 2a,b could be established via 13C nmr and high resolution 1H nmr to be the spiropyranylindolone derivatives 5a‐d.
Synthesis of pyrido[1′,2′:1,2]imidazo[4,5‐b]pyrazines from 2,3‐dichloro‐5,6‐dicyanopyrazine with 2‐aminopyridines
Authors: Suzuki Toshinobu , Nagae Yasushi , Mitsuhashi Keiryo
Published: March 2009

Novel synthesis of the title compounds by the facile cyclization between 2,3‐dichloro‐5,6‐dicyanopyrazine and various 2‐aminopyridines under relatively mild conditions is described. The reactivity depended on the basicity of 2‐aminopyridines.
Synthesis and spectral behavior of 5‐methyl‐3‐phenyl‐1,3‐oxazolidin‐2‐ones using NMR
Authors: Nishiyama Tomihiro , Matsui Shigeki , Yamada Fukiko
Published: March 2009

Heterocyclic compounds of four 5‐methyl‐3‐phenyl‐1,3‐oxazolidin‐2‐ones have been synthesized by the reaction of N‐2‐hydroxyethyl‐ or N‐2‐hydroxypropylanilines with phosgene in the presence of pyridine. From the spectral behavior, the title compounds are found to exist in the trans and cis forms.
Novel eight‐membered heterocycles. Synthesis of dithiazolo[4,5‐d:5′,4′‐g][1,3]diazocine derivatives
Authors: Rahman Loay K. A.
Published: March 2009

A number of derivatives of dithiazolo[4,5‐d:5′,4′‐g][1,3]diazocine have been prepared by the ring closure of the diaminodithiazole derivatives 7–8 or by replacement of the corresponding alkylthio‐function of 9–10.
Synthesis of pyrimidino[4,5‐b][1,5]benzodiazepin‐2‐ones and pyrimidino[1,6‐a]benzimidazol‐1‐ones from 4‐ethoxycarbonylamino‐1H‐1,5‐benzodiazpine‐3‐carbonitrile via 4‐(2‐aminoanilino)pyrimidin‐2(1H)‐one‐5‐carbonitriles
Authors: Takagi Kaname , Aotsuka Tomoji , Morita And Hikari , Okamoto Yoshihisa
Published: March 2009

Reactions of 4‐ethoxycarbonylamino‐1H‐1,5‐benzodiazepine‐3‐carbonitrile (2) with aliphatic primary amines gave 1‐substituted 4‐(2‐aminoanilino)pyrimidin‐2(1H)‐one‐5‐carbonitriles 3. Analogous reactions of 2 with aromatic primary amines afforded 2‐(2′‐anilino‐1′‐cyanovinyl)benzimidazoles 5 and 6. Upon treatment with triethylamine, 3 underwent intramolecular cyclization to give 3‐substituted 5‐aminopyrimidino[4,5‐b]‐[1,5]benzodiazepin‐2(3H,11H)‐ones 8. Heating of 3 with p‐toluenesulfonic acid in ethanol gave 2‐substituted pyrimidino[1,6‐a]benzimidazol‐1(2H)one‐4‐carbonitriles 9. Reactions of 2 with hydrazines were also described. Mechanistic pathways are proposed to account for the products.
Synthesis of heterocycles. Part VI. Synthesis and antimicrobial activity of some 4‐amino‐5‐aryl‐1,2,4‐triazole‐3‐thiones and their derivatives
Authors: Eweiss N. F. , Bahajaj A. A. , Elsherbini E. A.
Published: March 2009

4‐Amino‐5‐aryi‐1,2,4‐triazole‐3‐thiones I react with acid chlorides to yield 4‐acylamino‐5‐aryl‐1,2,4‐triazole‐3‐thiones II. Compounds I also react with methylene iodide, chloroacetonitrile and methyl bromoacetate to give bis‐(4‐amino‐5‐aryl‐1,2,4‐triazol‐3‐ylthio)methanes III, 4‐amino‐5‐aryl‐3‐cyanomethylthio‐1,2,4‐triazoles IV and 4‐amino‐5‐aryl‐3‐carbomethoxymethylthio‐1,2,4‐triazoles V, respectively. Compounds V react with hydrazine hydrate to give the corresponding acid hydrazides VI which in turn condenses with acid chlorides and aldehydes to afford respectively 1‐[(4‐amino‐5‐aryl‐1,2,4‐triazol‐3‐ylthio)acetyl]‐2‐aroylhydrazines VII and aryl methylene (4‐amino‐5‐aryl‐1,2,4‐triazol‐3‐ylthio)acethydrazones VIII. The antimicrobial activities of the above compounds were screened against different strains of bacteria and fungi.
Rearrangements of 4‐(2‐Aminophenyl)‐1,4‐dihydro‐2,6‐dimethyl‐3,5‐pyridinedicarboxylic acid diethyl ester
Authors: Kim Dong H.
Published: March 2009

The treatment of 4‐(2‐aminophenyl)‐1,4‐dihydro‐2,6‐dimethyl‐3,5‐pyridinecarboxylic acid diethyl ester (III) with refluxing toluene or pyridine afforded 1,2,3,6‐tetrahydro‐2,4‐dimethyl‐2,6‐methano‐1,3‐benzodiazocine‐5,11‐dicarboxylic acid diethyl ester (IV) as the major product. In addition, the following minor products were isolated: 2‐methyl‐3‐quinolinecarboxylic acid ethyl ester (V), 3‐(2‐aminophenyl)‐5‐methyl‐6‐azabicyclo[3,3,1]‐hept‐1‐ene‐2,4‐dicarboxylic acid diethyl ester (VI), and 5,6‐dihydro‐2,4‐dimethyl‐5‐oxobenzo[c][2,7]naphthyridine‐1‐carboxylic acid ethyl ester (VII). In contrast, acidic conditions caused the conversion of III into V in a 95% yield. The formation of the latter appears to involve IV as an intermediate, since IV degraded rapidly in acid to give V in a quantitative yield.
13C NMR spectra of 1,3‐oxathiolane, 1,3‐oxathiolane 3‐oxide and 1,3‐oxathiolane 3,3‐dioxide derivatives
Authors: Teodori E. , Melani F. , Gualtieri F.
Published: March 2009

Carbon‐13 nmr spectra of several 1,3‐oxathiolane, 1,3‐oxathiolane‐3‐oxide and 1,3‐oxathiolane‐3,3‐dioxide derivatives are reported. Relationships between some stereochemical features and chemical shift are discussed.
Reactions of triacetic acid lactone with carbonyl compounds. X‐Ray structure determination of 3‐acetoacetyl‐2‐chromenone and 3,6,9,12‐tetramethyl‐1H,6H,7H,12H‐6,12‐methanodipyrano[4,3‐b:4,3‐f]‐dioxocin‐1,7‐dione
Authors: De March P. , Moreno‐Mañas M. , Roca J. L. , Germain G. , Piniella J. F. , Dideberg O.
Published: March 2009

The structure of 3‐acetoacetyl‐2‐chromenone has been definitely assigned to the product resulting from the reaction of 4‐hydroxy‐6‐methyl‐2‐pyrone, 1, with 2‐hydroxybenzaldehyde. Also, the reaction of the pyrone 1 with pentane‐2,4‐dione in a 2:1 molar ratio gives 3,6,9,12‐tetramethyl‐1H,6H,7H,12H‐6,12‐methanodypirano[4,3‐b:4,3‐f]dioxocin‐1,7‐dione. X‐Ray analyses of both products are presented.
The reaction of pyridazinones with nucleophiles. An unusual reaction with cyanide
Authors: Badger Edward W. , Moos Walter H.
Published: March 2009

Studies on the synthesis of pyridazinone analogues of pyridone cardiotonics are reported. The synthetic scheme involves the reaction of pyridazinones and chloropyridazinones with nucleophiles. Addition occurred twice with cyanide as the nucleophile, thus providing a novel dicyanopyridazinone.
Synthesis of new spirobenzazolines including a furo[3,4‐b]pyran ring system
Authors: Coudert P. , Couquelet J. M. , Tronche P.
Published: March 2009

A series of 4,5‐dihydrofuro[3,4‐b]pyran‐6‐spiro‐2′‐benzazolines 3 were prepared by reaction of 4,4‐dimethyl‐2,6‐dioxo‐4,5‐dihydrofuro[3,4‐b]pyran 1 with o‐phenylenediamine, o‐aminophenol, o‐aminothiophenol or their derivatives. Most of these compounds exhibited a significant analgesic activity.
Nitrations of 4′,5′‐dihydropsoralens: A route to radiopharmaceutical precursors
Authors: Heindel Ned D. , Foster Natalie , Varkey Thankamma
Published: March 2009

Unlike the nitration of the fully‐aromatic furocoumarin, methoxsalen, which yields a single nitration product, the nitration of the 4′,5′‐dihydro compound generates a condition‐variant mixture of three nitro products. Reduction, diazotization, and pyrrolidine‐trapping of one of these, the 4′,5′‐dihydro‐5‐nitro‐8‐ methoxypsoralen, provides a pyrrolidine triazene precursor for radioiodination of the dihydropsoralen system.
Assignment of the 1H‐ and 13C‐NMR spectra of congested helicenes using two‐dimensional NMR methods: Phenanthro[3′,4′:3,4]phenanthro[2,1‐b]thiophene
Authors: Zektzer Andrew S. , Stuart John G. , Martin Gary E. , Castle Raymond N.
Published: March 2009

Phenanthro[3′,4′:3,4]phenanthro[2,1‐b]thiophene has been prepared and its highly congested proton and carbon nmr spectra assigned. The nmr assignments required concerted utilization of two‐dimensional nmr techniques which included: COSY, direct and long range optimized heteronuclear chemical shift correlation and heteronuclear relayed coherence transfer.
New heterocycles derived from a simultaneous substitution and reductive acetylation of 2,5‐dihydroxy‐1,4‐benzoquinone by N‐containing heterocycles
Authors: Farfán N. , Ortega E. , Contreras R.
Published: March 2009

Reaction of 2,5‐dihydroxy‐1,4‐benzoquinone with pyridine, 3‐picoline and acridine in acetic anhydride lead to the preparation of 3‐(4‐pyridyl)‐1,2,4,5‐benzenetetrol tetraacetate, 3‐[4‐(3‐methylpyridyl)]‐1,2,4,5‐benzenetetrol tetraacetate and 3‐(9‐acridyl)‐1,2,4,5‐benzenetetrol tetraacetate, respectively. Moreover, it was possible to isolate the complex derived from the corresponding amines and the quinone. The reaction conditions and the 1H, 13C, ir and mass spectra of the new compounds are discussed.
Synthesis of 4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine
Authors: Moron Jacqueline , Bisagni Emile
Published: March 2009

4‐Methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine (3) was synthetized from 2‐acetylfuro[3,2‐f]benzo[b]furan (4) or from 2‐acetyl‐5,6‐dihydrofuro[3,2‐f]benzo[b]furan (10). The key step involves a rearrangement‐cyclization of azides 6 and 12 to form 4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridin‐1(2H) one (7) and 8,9‐dihydro‐4‐methylfuro[3′,2′:5,6]benzofuro[3,2c]pyridin‐1(2H)‐one (13). Introduction of an aminoalkyl chain on carbon 1 was effected by substitution of 1‐chloro‐4‐methylfuro[3′,2′:5,6]benzofuro[3,2‐c]pyridine (8).
Proton‐Ionizable crown compounds. 7. Synthesis of new crown compounds containing the dialkylhydrogenphosphate moiety
Authors: Bradshaw Jerald S. , Huszthy Peter , Izatt Reed M.
Published: March 2009

A new series of macrocyclic ligands containing the dialkylhydrogenphosphate moiety is reported. These compounds were prepared by reacting phosphorus oxychloride with the appropriate oligoethylene glycol followed by a hydrolysis step. One of these new macrocyclic compounds transported the alkali metal cations as well as lead, zinc and silver ions.
Studies on pyrazines. 15. A convenient synthesis of 2,5‐dihydroxypyrazines
Authors: Sato Nobuhiro , Kato Yukihiro
Published: March 2009

The reaction of 2,5‐dimethoxypyrazines with iodotrimethylsilane followed by hydrolysis was investigated to prepare the title compounds.
Synthesis of heterocyclic propellanes via 1,3‐dipolar cycloaddition reactions to bicyclo[5.3.0]dec‐1(7)‐en‐2‐onea
Authors: Coutouli‐Argyropoulou E. , Malamidou‐Xenikaki E.
Published: March 2009

The synthesis of several heterocyclic propellanes via 1,3‐dipolar cycloaddition reactions of arylnitrile oxides, diarylnitrilimines and arylazides with bicyclo[5.3.0]dec‐1(7)‐en‐2‐one is described and the spectral properties of the obtained propellanes are discussed. The cycloadditions are also examined on the basis of frontier molecular orbitals (FMO) of the reacting species.
Synthesis of 11‐aza‐5H‐benzophenoxazin‐5‐one and 11‐Aza‐5H‐pyridophenoxazin‐5‐one derivatives
Authors: Nan'ya Seiko , Maekawa Eturô , Kang Wen‐Bing , Ueno Yoshio
Published: March 2009

The 1,6‐disubstituted‐ and 4,6‐disubstituted‐11‐aza‐5H‐benzo[a]phenoxazin‐5‐one as well as 6‐substituted‐11‐aza‐5H‐pyrido[a]phenoxazin‐5‐one derivatives were prepared by the condensation of 2‐amino‐3‐hydroxypyridine with 5‐substituted‐2,3‐dihalogeno‐1,4‐naphthoquinones and 6,7‐dibromo‐5,8‐quinolinequinone respectively. The resulting compounds were subjected to reduction, acetylation, dehalogenation and reaction with aniline.
A novel synthesis of benzofuran and related compounds. III. The vilsmeier reaction of phenoxyacetaldehyde diethyl acetals
Authors: Hirota Takashi , Fujita Hiroko , Sasaki Kenji , Namba Tetsuto
Published: March 2009

A novel synthesis of 2‐benzofurancarbaldehydes by the Vilsmeier reaction of phenoxyacetaldehyde diethyl acetals is described.
Réactivité des cinnamoyl‐3 pyrones‐2 vis à vis des amines primaires
Authors: Chergui Djamel , Hamdi Maâmar , Baboulène Michel , Spéziale Vincent , Lattes Armand
Published: March 2009

L'action d'amines primaires (méthylamine, isopropylamine, benzylamine) en milieu neutre, sur des cinnamoyl‐3 pyrones‐2 s'effectue avec ouverture du cycle suivie d'une décarboxylation. La structure des amino‐7 dioxo‐3,5 octadiènes‐1,6 (2) ainsi obtenus a été déterminée par différentes méthodes: analyse élémentaire, spectrométrie de masse, rmn1H et 13C.
Synthesis of 1‐ and 4‐substituted‐5H‐benzo[a]phenoxazin‐5‐ones
Authors: Hayakawa Hitoshi , Nan'ya Seiko , Yamamoto Tetsuo , Maekawa Eturô , Ueno Yoshio
Published: March 2009

The 1‐ and 4‐substituted‐5H‐benzo[a]phenoxazin‐5‐ones (substitutents: nitro, amino and acetylamino) were prepared by the condensation of o‐aminophenol with 5‐substituted‐2,3‐dichloro‐1,4‐naphthoquinones. The resulting compounds were subjected to reduction, acetylation and dehalogenation.
1H‐NMR, Ultraviolet and infrared spectra of some (Z)‐α‐(phenyl)‐β‐(2‐furyl), ‐(2‐pyrrolyl) and ‐(N‐methyl‐2‐pyrrolyl)acrylonitriles
Authors: Alberghina Gaetano , Amato Maria Emanuela , Bottino Francesco Agatino , Corsaro Antonino , Fisichella Salvatore
Published: March 2009

The 1H‐nmr data of some (Z)‐α‐(p‐substituted‐phenyl)‐β‐(2‐furyl), ‐(2‐pyrrolyl), and ‐(N‐methyl‐2‐pyrrolyl)‐acrylonitriles have been investigated to indicate the preferred conformation and to establish the conformational preferences of the β‐heterocyclic ring. The ultraviolet spectra have been discussed in order to obtain information about the chromophores responsible for the absorption. The infrared spectra have been analyzed for the identification of the main absorption frequencies of cyano and ethylenic groups and to assign the characteristic absorption bands to specific normal vibrations of the heteroaromatic nuclei.
Studies on pyrrolidinones. Michael reaction of glutamic acid and diethylglutamate
Authors: Rigo Benoît , Couturier Daniel , Kolocouris Nicolas
Published: March 2009

Starting from glutamic acid or diethyl glutamate, some derivatives of N‐(2‐carboxyethyl), N‐(3‐oxobutyl) and N‐(2‐cyanoethyl)pyroglutamic acid were synthesized.
Heterocyclic compound studies. II. Synthesis of 1,4‐benzodioxin, 1,4‐benzoxathiin, 1,4‐benzoxazine and 1,4‐benzothiazine derivatives
Authors: Cabiddu Salvatore , Floris Costantino , Melis Stefana , Sotgiu Francesca , Cerioni Giovanni
Published: March 2009

Benzocondensed six‐membered heterocyclic rings containing two heteroatoms have been synthesized by a generally applicable method starting from disubstituted benzene compounds and methyl 4‐chlorobutynoate (1) or methyl 4‐bromobutenoate (2). The reactions with 1 yield a mixture of endo and exo (E or Z) isomers. The 13C nmr spectroscopy was used to assign the structure of the synthesized compounds.
Proton‐Ionizable crown compounds. 8. Synthesis and structural studies of macrocyclic polyether ligands containing a 4‐thiopyridone subcyclic unit
Authors: Bradshaw Jerald S. , Huszthy Peter , Koyama Hiroyuki , Wood Steven G. , Strobel Scott A. , Davidson Richard B. , Izatt Reed M. , Dalley N. Kent , Lamb John D. , Christensen James J.
Published: March 2009

Three new proton‐ionizable macrocyclic polyether ligands containing the 4‐pyridone subcyclic group have been prepared. Two of these ligands contain lipophilic n‐octyl substituents, the other ligand contains a phenyl substituent. The 15‐crown‐5 ligand containing both a 4‐pyridone subcyclic unit and an n‐octyl substituent selectively transported lithium cations in a water‐methylene chloride‐water bulk liquid membrane system. Five crown compounds containing the 4‐pyridone subcyclic unit were converted to the 4‐thiopyridono‐crown compounds when treated with Lawesson's Reagent. The crystal structure of 4‐thiopyridono‐18‐crown‐6 shows a carbon‐sulfur double bond and a molecule of water hydrogen bonded inside the macrocycle cavity.
Synthesis of certain 3‐alkoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidines structurally related to adenosine, inosine and guanosine
Authors: Anderson Jack D. , Dalley N. Kent , Revankar Ganapathi R. , Robins Roland K.
Published: March 2009

Several 3‐alkoxysubstituted pyrazolo[3,4‐d]pyrimidine ribonucleosides structurally related to adenosine, inosine and guanosine have been prepared by the direct glycosylation of preformed aglycon precursor containing a 3‐alkoxy substituent. Ring closure of 5(3)‐amino‐3(5)‐ethoxypyrazole‐4‐carboxamide (6b) with either formamide or potassium ethyl xanthate gave 3‐ethoxyallopurinol (7b) and 3‐ethoxy‐6‐thioxopyrazolo[3,4‐d]‐pyrimidin‐4(5H,7H)‐one (10), respectively. Methylation of 10 gave the corresponding 6‐methylthio derivative 15. Similar ring annulation of 5(3)‐methoxypyrazole‐4‐carboxamide (6a) with formamide afforded 3‐methoxyallopurinol (7a). Treatment of 5(3)‐amino‐3(5)‐methoxypyrazole‐4‐carbonitrile (5a) with formamidine acetate furnished 4‐amino‐3‐methoxypyrazolo[3,4‐d]pyrimidine (4). High‐temperature glycosylation of 7b with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐D‐ribofuranose in the presence of boron trifluoride etherate gave a 2:1 mixture of N‐1 and N‐2 glycosyl blocked nucleosides 11b and 13b. Deprotection of 11b and 13b with sodium methoxide gave 3‐ethoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (12b) and the corresponding N‐2 glycosyl isomer 14b, respectively. Similar glycosylation of either 4 or 7a, and subsequent debenzoylation gave exclusively 4‐amino‐3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidine (9) and 3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4‐(5H)‐one (12a), respectively. The structural assignment of 12a was made on the basis of single‐crystal X‐ray analysis. Application of this general glycosylation procedure to 15 gave the corresponding N‐1 glycosyl derivative 16 as the sole product, which on debenzoylation afforded 3‐ethoxy‐6‐(methylthio)‐1‐(3‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (17). Oxidation of 16 and subsequent ammonolysis furnished the guanosine analog 6‐arnino‐3‐ethoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]‐pyrimidin‐4(5H)‐one (19). Similarly, starting from 3‐methoxy‐4,6‐bis(methylthio)pyrazolo[3,4‐d]pyrimidine (20), 6‐amino‐3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (23) was prepared.
Desulfation and rearrangement of tigemonam to an isoxazolidin‐5‐one and the synthesis of the rearrangement product
Authors: Singh Janak , Kissick Thomas P. , Fox Rita , Kocy Octavian , Mueller Richard H.
Published: March 2009

The β‐lactam antibiotic Tigemonam 2 undergoes desulfation to the N‐hydroxyazetidinone 4, which rearranges to the isoxazolidin‐5‐one 6. The structure of the rearrangement product 6 was confirmed by synthesis.
Reactions of 2‐, 3‐, and 4‐(N‐nitroso)methylaminopyridine with esters containing active methylene groups
Authors: Kiriazis L. , Kalatzis E. , Alexandrou N. E.
Published: March 2009

2‐N‐Nitrosomethylaminopyridine but not 2‐methylaminopyridine, 3‐N‐nitrosomethylamino‐ or 3‐methyl‐aminopyridine and 4‐N‐nitrosomethylamino‐ or 4‐methylaminopyridine react with malonate esters to form the corresponding derivatives of carbamates, amides and dihydropyridines respectively. In the reaction of the 4‐isomers with diisopropyl malonate small amounts of the corresponding carbamates was also formed.
Synthèse de dioxinocoumarines angulaires
Authors: Guillaumet Gérald , Hretani Mohamed , Coudert Gérard
Published: March 2009

Les synthèses des dioxinocoumarines angulaires 1 et 2 apparentées aux angélicines sont décrites. Elles sont réalisées respectivement en huit et dix étapes à partir de l'amino‐6 benzodioxanne‐1,4 et du méthoxy‐3 catéchol.
Novel crown ethers with pendant, proton‐ionizable, chromogenic groups
Authors: Czech Bronislaw P. , Babb David A. , Czech Anna , Bartsch Richard A.
Published: March 2009

Synthesis of fifteen new chromogenic crown ethers is described in which one phenyl group of diphenylamine has been substituted at the 2‐, 4‐, and 6‐positions with strongly electron‐withdrawing groups and the other phenyl group bears an oxymethyl crown ether substituent. Structural variations include the crown ether ring size, identity of the electron‐withdrawing groups, acidity of the amine function, and positioning of the oxymethyl crown ether substituent ortho, meta, and para to the amine nitrogen. Preparation of a structurally‐related chromogenic bis(crown ether) is also reported.
Heterocycles. Part XVII. Synthesis of new substituted 2,3,3a,4,5,6‐hexahydrobenzo[6,7]cyclohepta[1,2‐c]pyrazoles and related compounds
Authors: El‐Rayyes N. R. , Bahtiti N. H.
Published: March 2009

Aryl aldehydes I reacted with 1‐benzosuberone to yield the corresponding 2‐arylidene‐1‐benzosuberones II. Condensation of II with hydrazine and its derivatives provided the substituted 2,3,3a,4,5,6‐hexahydro‐benzo[6,7]cyclohepta[1,2‐c]pyrazoles III‐VI respectively. The structures of all products were assigned by chemical and spectroscopic methods.
Reaction of 2,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole with primary amines. Synthesis of 4‐substituted‐3,5‐bis(trifluoromethyl)‐4H‐1,2,4‐triazoles
Authors: Reitz David B. , Finkes Michael J.
Published: March 2009

Reaction of 3,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole (1a) with primary amines under a variety of conditions conveniently produced 4‐substituted‐3,5‐bis(trifluoromethyl)‐4H‐1.2,4‐triazoles 4a in 26‐85% yield. Alkyl amines reacted with 1a in methanol at −42° to provide hydrogen‐bonded monoadduct‐methanol complexes 5a, as determined by X‐ray. The reaction of 1a with sterically hindered or strongly electron deficient anilines required high temperatures in the absence of solvent.
The synthesis and properties of 2‐substituted dihydropyrimidines
Authors: Kashima Choji , Shimizu Masao , Omote Yoshimori
Published: March 2009

Various 2‐substituted 1,4‐dihydro‐4,4,6‐trimethyl‐1‐phenylpyrimidines and 1,6‐dihydro‐4,6,6‐trimethylpyrimidines were synthesized independently. For these dihydropyrimidines, the physical data such as the uv, ir, and nmr spectra and the oxidation potential were compared. 2‐Dimethylamino substituted dihydropyrimidine showed the lowest oxidation potential, which expected the similar reducing ability as dihydropyridines.
Constantes d'acidité de quelques bihétérocycles
Authors: Tjiou El Mostafa , Fruchier Alain , Pllegrin Valdo , Tarrago Georges
Published: March 2009

Les pKa1 et pKa2 de 19 bihétérocycles de formule générate A‐(CH2)n‐B (où A et B représentent un pyrazole, un imidazole ou une pyridine, et n = 0 ou 1) sont déterminés dans l'eau à 25° par potentiométrie et par spectrométrie uv.
Synthesis and 1H‐, 13C‐NMR analysis of some substituted 1,2,3,4‐tetrahydroisoquinolines
Authors: Ibañez A. F. , Yaculiano G. B. , Iglesias G. Y. Moltrasio
Published: March 2009

Synthesis and 1H‐, 13C‐nmr analysis of some substituted 3‐phenyl‐1,2,3,4‐tetrahydroisoquinolines are reported. Spectroscopy assignments of hydrogen and carbon resonances were made on the basis of standard chemical shift theory, comparison with reference compounds, attached proton test and fully coupled 13C‐nmr spectra. Data showed that at room temperature two conformers predominated for the 1,3‐disubstituted and 1,2,3‐trisubstituted isoquinolines.
Synthesis of N‐heterocycles via chalcone epoxides. 1. Amino and hydrazinopyrimidines
Authors: Osisanya Rasaki Abayomi , Oluwadiya James Olabisi
Published: March 2009

Chalcone epoxides have been used as precursors in the synthesis of 2‐amino‐ and 2‐hydrazinopyrimidines.
On triazoles XVIII. . an unexpected rearrangement observed during the reaction of 5‐amino‐1,2,4‐triazoles with N‐heterocyclic β‐oxo‐esters
Authors: Reiter JóZsef , Rivó Endre
Published: March 2009

In the course of the synthesis of pyrido[4,3‐d]‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives 3c representing a novel ring system an unexpected rearrangement of the intermediate enamines to yield 5 was observed. A mechanism of the formation of 5 was suggested. The isomeric pyrido[4,3‐e]‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives 4c containing also a new ring system were obtained, too. The structure of products obtained was proved with the help of their uv, cmr and X‐ray spectra.
Synthèse de C‐nucléosides dérivés de l'hydroxy‐8 (1,2,4)triazolo[1,5‐c] et [4,3‐c]pyrimidines
Authors: Dennin F. , Rousseaux O. , Blondeau D. , Sliwa Et H.
Published: March 2009

Les ethers et esters correspondant aux nouveaux C‐nucléosides β‐D‐ribofuranosyl‐2‐hydroxy‐8(1,2,4)triazolo[1,5‐c]pyrimidine et (hydroxy‐2 ethoxymethyl)‐2 hydroxy‐8 (1,2,4)triazolo[1,5‐c]pyrimidine ont été obtenus par condensation de la benzyloxy‐5 hydrazino‐4 pyrimidine avec le chlorhydrate de benzoyloxy‐5 β‐D‐ribofuranosyl formimidate de thiobenzyle pour les premières et avec les chlorhydrates de (benzoyloxy‐2 éthoxy)‐2 acétimidate d'éthyle ou de thiobenzyle pour les seconds. L'action du méthanol ammoniacal suivie d'hydrogénolyse permet d'accéder à ces nouveaux C‐nucléosides, dérivés de phénols hétérocycliques dont les structures ont été établies par uv, ir et rmn.
Pyridazines. XLV . on the mechanism of an unusual 1,2‐diazine → 1,2‐diazole ring contraction
Authors: Heinisch Gottfried , Huber Thierry , Langer Christina , Gössler Walter , Kollenz Gert
Published: March 2009

Starting with succinic acid‐2,3‐13C, phenyl(4‐pyridazinyl)methanol‐4,5‐13C was prepared in order to gain insight into the mechanism of an unusual pyridazine into pyrazole rearrangement reported previously. According to the 13C‐nmr spectrum of labeled 1‐phenyl‐2(4‐pyrazolyl)ethanone obtained upon p‐toluenesulfonic acid mediated ring contraction, the methylene and the pyrazole C‐4 carbon atoms of the reaction product originate from the pyridazine carbon atoms 4 and 5 of the educt. Thus, a mechanism for this ring‐transformation is proposed involving well stabilized carbocations as intermediates.
Nitrogen bridgehead compounds. Part 76 Synthesis and stereochemistry of ethyl 9‐benzylidene‐6,7,8,9‐tetrahydro‐2‐oxo‐2H‐ and 4‐oxo‐4H‐pyrido[1,2‐a]pyrimidine‐3‐carboxylates and their homologues
Authors: Sipos Judit , Podányi Benjamin , Hermecz István , Pusztay Levente , Tóth Gábor , Szilágyi László
Published: March 2009

Ethyl 4‐oxo‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyrimidine‐3‐carboxylates 1–4, their piperidine ring homologues 5–6 and their 2‐oxo isomers 7–9 were reacted with benzaldehyde. At low temperature, kinetically stable addition products were formed. Thermodynamically stable condensation products were obtained at higher temperature, which were also formed when the addition products were refluxed in benzene. The 9‐benzyl derivatives were prepared by the hydrogenation of the condensation products over Pd/C. The stereochemical features of the new compounds were determined via 1H and 13C nmr chemical shift and coupling constant analysis and NOE measurements.
Reaction of 6‐aminopyrimidin‐4‐ones with diethyl ethoxymethylenemalonate in several media: Synthesis of pyrido[2,3‐d]pyrimidines
Authors: García José A. , Sánchez Adolfo , Nogueras Manuel
Published: March 2009

Reactions of 6‐amino‐3,4‐dihydro‐2‐methoxy‐4‐oxopyrimidine 1 and its 3‐methyl derivative 2, with diethyl ethoxymethylenemalonate (EMME) are discussed in this paper. These reactions have been carried out in the following media: under fusion, ethanol, sodium methoxide/methanol, sodium ethoxide:ethanol and acetic acid media. In acetic medium, mixtures of products proceeding from C‐alkylation and N‐alkylation were obtained, while in the remaining conditions only products of N‐alkylation were obtained.
Synthèse de pyrimidines et purines adamantylées par alkylation régiosélective directe, en catalyse par transfert de phase
Authors: Hedayatullah Mir , Roger Annie
Published: March 2009

La monoalkylation régiosélective de l'uracile, de la thymine, de l'adénine, de l'aza‐8 adénine et de la théophylline est réalisee par l'emploi d'un alkylant dérivé de l'adamantane, en catalyse par transfert de phase. Dans les měmes conditions, le barbital et le phénobarbital ont fourni les dérivés N1,H3‐dialkyles correspondants. L'influence de la nature de l'agent alkylant sur la sélectivité observée est discutée.
1H and 13C NMR and x‐ray diffraction studies on pyrazolo[1,5‐b][1,2,4]triazine — A new heterocyclic system
Authors: Sliskovic D. Robert , Ashcroft Joseph , Morton George O. , James John C. , Lin Yang‐I.
Published: March 2009

The 1H and 13C nmr resonances of pyrazolo[1,5‐b][1,2,4]triazine (1) were assigned and the structure of its 2,3‐dimethyl derivative 2 was determined using X‐ray crystallography.
A selective synthesis of 1‐aryl‐3‐quinoxalinyl‐1,2,4‐triazole and furo[2,3‐b]quinoxaline
Authors: Kim Ho Sik , Kurasawa Yoshihisa , Takada Atsushi
Published: March 2009

The reaction of the ester 1 with ethyl benzoate‐2‐diazonium chloride gave the α‐arylhydrazonoester 2b, whose reaction with hydrazine hydrate afforded the α‐arylhydrazonoacylhydrazide 3b. The reaction of 3b with sodium nitrite in water/acetic acid under heating on a boiling water bath provided the 1‐aryl‐3‐quin‐oxalinyl‐1,2,4‐triazole 5b, presumably via the α‐arylhydrazonoacylazide 4b, while the isolation of 4b and then its refluxing in dioxane/water furnished the furo[2,3‐b]quinoxaline 6. The tautomeric behavior of 2b and 3b between the hydrazone imine and diazenyl enamine forms was described together with the tautomer ratio determined by the nmr spectral data.
Tautomeric structure of dihydropyrazolo[1,5‐a]‐pyrimidin‐7‐one in a solution. A facile synthesis of novel 6‐quinoxalinyldihydropyrazolo[1,5‐a]pyrimidin‐7‐ones by ring transformation
Authors: Kurasawa Yoshihisa , Kim Ho Sik , Futatsukawa Rika , Watanabe Chisako , Takada Atsushi , Okamoto Yoshihisa
Published: March 2009

6‐Quinoxalinyldihydropyrazolo[1,5‐a]pyrimidin‐7‐ones 4a‐d were synthesized by the ring transformation of 3‐(N,N‐dimethylcarbamoyl)furo[2,3‐b]quinoxaline hydrochloride 5. Compounds 4a‐d were found to exist as the 4,7‐dihydro‐7‐oxo form E in dimethyl sulfoxide based on the nmr spectral data.
A new synthesis of 2′,3′‐dideoxycytidine
Authors: Kaskar Bashir , Markovac Anica
Published: March 2009

A new synthesis of 2′,3′‐dideoxycytidine is described and the utility of this synthesis to prepare larger quantities of said nucleoside is shown.
Preparation and alkylation of 1,5‐dihydro‐3H‐1,2,4‐thiadiazolo[3,4‐b]quinazolin‐5‐one 2,2‐dioxides
Authors: Demers James P. , Sulsky Richard , Klaubert Dieter H.
Published: March 2009

1,5‐Dihydro‐3H‐1,2,4‐thiadiazolo[3,4‐b]quinazolin‐5‐one 2,2‐dioxides (3) are prepared by reaction of isatoic anhydrides with methyl N‐(chloromethanesulfonyl)carbamimidothioate (6). The sodium salt of 3a, generated with sodium hydride in N,N‐dimethylformamide, is alkylated excusively on N‐10. An improved preparation of 6 is described, utilizing a two‐phase sulfonylation.
Quinolizines and indolizines. Part 16. Synthesis of pyrrolo[3,2,1‐ij]quinolin‐4‐ones with potential fungicidal activity
Authors: Kappe C. Oliver , Kappe Thomas
Published: March 2009

The synthesis of some derivatives of 1,2,5,6‐tetrahydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐one (pyroquilon) having potential fungicidal activity has been accomplished starting with readily available 6‐hydroxy‐1,2‐dihydro‐4‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 3, 7. Functionalization in 6‐ or 5‐position gave rise to the corresponding 6‐and 5‐substituted derivatives 8‐12, 17 and 13‐16, 20, 21 respectively. The formation of pyrrolo[3,2,1‐ij]‐pyrano[3,2‐c]quinolines (5, 22, 23) and their degradation to acyl‐substituted derivatives of 7 was studied.