bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and synthesis of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine nucleis through multicomponent reaction under microwave irradiation
Authors: Tu Shujiang , Wang Qian , Zhang Yan , Xu Jianing , Zhang Jinpeng , Zhu Xiaotong , Shi Feng 
Published: March 2009

Abstractmagnified imageA series of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine moieties has been synthesized through a rapid one‐pot three‐component reaction of dialdehyde, 5‐amino‐3‐methyl‐1‐phenylpyrazole and active methylene compounds in glycol under microwave irradiation without catalyst. The method has the advantages of good yield (85‐98%), short route and reaction time (45‐300s), wide reaction scope and easy work‐up procedure.
Mn(III) acetate mediated diasteroselective [3+2] oxidative addition of 1,3‐dicarbonyl compounds with chalcones
Authors: Shanmugam Pachiappa N. , Kumar Kalv I. Hemanth , Perumal Paramasiva N. T. 
Published: March 2009

Abstractmagnified imageA diastereoselective synthesis of 4,5‐dihydrofurans by oxidative addition of 1,3‐dicarbonyl compounds with chalcones mediated by Mn(OAc)3 in moderate to good yields is reported.
Syntheses, electrochemical studies and crystal structures of new unsymmetrical tetrathiafulvalene carboxylate derivatives
Authors: Liu Wei , Guo Yun‐Jun , Zuo Jing‐Lin , You Xiao‐Zeng , Zeng Xi‐Rui 
Published: March 2009

Abstractmagnified imageA series of new unsymmetrical tetrathiafulvalene carboxylate derivatives (7‐11) were synthesized and characterized by NMR, MS, electrochemical studies and X‐ray crystal structural determination. Compound 8 showed obvious changes in redox peak potentials as the concentration of p‐toluenesulfonic acid changes.
The first synthesis of furazano[3,4‐b][1,6]naphthyridines
Authors: Vasilev Leonid S. , Sheremetev Aleksei B. , Dorokhov Vladimir A. , Suponitsky Kyrill Yu. 
Published: March 2009

Abstractmagnified imageReaction of 6‐acetyl‐7‐aminofurazano[3,4‐b]pyridines with DMFDMA afforded N,N‐dimethylformamidines that were cyclized to the novel furazan‐fused [1,6]naphthyridine system by treatment with sodium methylate in good yield. The tricyclic system is characterized by X‐ray crystallography.
A novel photoisomerzation of 1,2‐benzothiazine 1,1‐dioxides to 1,3‐benzothiazine 1,1‐dioxides
Authors: Elghamry Ibrahim , Döpp Dietrich , Henkel Gerald 
Published: March 2009

AbstractA novel facile photoconversion of 4‐hydroxy‐1,2‐bezothiazine 1,1‐dioxides (3a‐e) into 4‐oxo‐1,3‐2H‐benzothiazine 1,1‐dioxides (4a‐e) and 4‐hydroxy‐2‐methyl‐N‐(pyridin‐2‐yl)‐2H‐1,2‐benzothiazine‐3‐carboxamide 1,1‐dioxide (PRX) into N‐methyl saccharin (2) upon 254 nm irradiation in methanol or acetonitrile is reported. The structures of the products have been elucidated by spectroscopic methods and single crystal X‐ray structure determination for 4a and 4d.
Synthesis of thiophene/phenylene co‐oligomers. V. Functionalization at molecular terminals toward optoelectronic device applications
Authors: Katagiri Toshifumi , Ota Satoshi , Ohira Takayuki , Yamao Takeshi , Hotta Shu 
Published: March 2009

AbstractWe report the synthesis of various thiophene/phenylene co‐oligomers with a total number of thiophene and benzene (phenylene) rings of 5 and 6 with various terminal groups. Those terminal groups have been chosen from among alkyl groups, methoxy groups, trifluoromethyl groups, and cyano groups. The molecular backbone of these compounds comprises phenyl‐ or biphenylyl‐capped thiophene (or oligothiophene) or an alternating co‐oligomer. The synthesis is based on either the Suzuki coupling reaction or the Negishi coupling reaction. These reaction schemes enabled us to obtain the target compounds in high quality. In particular, the latter coupling method turned out to produce the compounds at a high yield. The terminal groups are expected to produce various functionalities based upon their electron donating character (alkyl groups and methoxy groups) or electron withdrawing character (trifluoromethyl groups and cyano groups). Additionally some of these groups bring about enhanced solubility. This will lead to the production of a diversity of modified compounds of thiophene/phenylene co‐oligomers. To give an example that demonstrates usefulness of the target compounds, we present optoelectronic data that are associated with their device applications.
Microwave assisted synthesis of coumarins via potassium carbonate catalyzed knoevenagel condensation in 1‐n‐butyl‐3‐methylimidazolium bromide ionic liquid
Authors: Valizadeh Hassan , Gholipur H. , Shockravi Abbas 
Published: March 2009

Abstractmagnified imageA variety of substituted coumarins have been prepared via an inexpensive and efficient potassium carbonate catalyzed Knoevenagel condensation of salisylaldehydes with acidic methylene compounds in ionic liquid media. 1‐n‐Butyl‐3‐methylimidazolium bromide has been employed as an alternative reaction medium in this procedure. The reaction proceeds smoothly under mild and solvent‐free conditions and the products are obtained in excellent yields. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method.
Synthesis of 7a‐aryl‐5‐t‐butyl‐3‐methyleneoctahydrobenzofuran possessing partial skelotons of some santonin analogue and furanolignans by intramolecular radical cyclisation reaction
Authors: Periasamy Marappagounder , Ponnuswamy Alagusundaram 
Published: March 2009

Abstractmagnified imageBicyclic octahydrobenzofuran derivatives (1c‐6c) possessing the partial skeletons of santonin (7), 11,13‐dehydroisohyposantonin (8), dihydrosesamin (9) and lariciresinol (10) have been synthesised by intramolecular radical cyclisation in good yield via the precursors viz., the trans diaxial bromopropynyl ethers (1b‐6b) obtained in highly regio/stereoselective manner.
Green chemistry approach to the synthesis of 2‐amino‐4‐aryl‐6‐ferrocenyl‐pyridine derivatives by a one‐pot reaction in aqueous medium
Authors: Zhuang Qiya , Jia Runhong , Tu Shujiang , Zhang Junyong , Jiang Bo , Zhang Yan , Yao Changsheng 
Published: March 2009

Abstractmagnified imageA clean and facile green chemistry method for the synthesis of a series of 2‐amino‐4‐aryl‐6‐ferrocenylpyridine derivatives was afforded. The products were synthesized via the one‐pot reaction of aromatic aldehyde, malononitrile or ethyl cyanoacetate, acetylferrocene and ammonium acetate in aqueous medium under microwave irradiation and conventional heating conditions without catalyst. This method had several advantages such as higher yield, lower cost, reduced environmental impact, and convenient procedure.
Synthesis and NMR analysis of spiranic heterocycles from carbohydrate derivatives
Authors: Alho Miriam A. Martins , D'Accorso Norma B. 
Published: March 2009

Abstractmagnified imageWe report the synthesis of some furanose and pyranose acylhydrazones and their heterocyclization products. The new compounds were characterized physically and spectroscopically and the syn‐anti and (R)‐(S) configuration was determined by NOESY experiments. We discuss the influence of the nucleophile, the temperature and the precursor structure on the heterocyclization products.
Synthesis and antitumor activities of 2‐(substituted)phenyl‐1,2,4‐triazolo[1,5‐a]pyridines
Authors: Zhang Guolin , Hu Yongzhou 
Published: March 2009

Abstractmagnified imageTwenty‐three 2‐(substituted)phenyl‐1,2,4‐triazolo[1,5‐a]pyridines have been synthesized by cycloadditison reaction between N‐amino methylpyridinium mesitylenesulfonates and substituted benzonitriles under the presence of potassium hydroxide at room temperature. The structures of all products were confirmed by 1H NMR, MS and elemental analyses. The antitumor activities of these compounds were evaluated against human ovary cancer cell line (HO‐8910) in vitro by MTT method. The preliminary results showed that compound 1e (IC50 28μM) and compound 1w (IC50 31μM) exhibited stronger antitumor activities than cisplatin (IC50 35μM) in vitro. Hence, 1e and 1w have potential antitumor activities and are worth further investigation.
Syntheses of acyclic C‐glycosidic derivatives of 1,2,4‐triazoles by cycloadditions of 1‐aza‐2‐azoniaallene salts to D‐glucononitrile‐2,3,4,5,6‐pentaacetate
Authors: Hassan N. A. 
Published: March 2009

Abstractmagnified imageReported are preparations of acyclic derivatives of 1,2,4‐triazole‐5‐glycosidies 9 by cycloadditions of 1‐aza‐2‐azonia‐allene salts 3 to the nitrile group of D‐glucononitrile‐2,3,4,5,6‐pentaacetate 5 affording triazolium salts 8, which with aqueous sodium hydogencarbonate are hydrolyzed to 9. Deacetylation of compounds 9 produced the C‐glycosides 10.
Studies with enamines and azaenamines: Synthesis and reactivity of 3‐dimethylamino‐2‐[(3‐indolyl) carbonyl]propenonitrile
Authors: Abdallah Tayseer A. 
Published: March 2009

Abstractmagnified image2‐Oxo‐3‐(indol‐3‐yl)propanonitrile 2 condensed with dimethylformamide dimethylacetal to yield the enaminonitrile 3. The latter reacted with 4‐chloroaniline to yield the 4‐chlorophenylaminoacrylonitrile 5. Reaction of 3 with hydrazine hydrate led to formation of pyrazole‐4‐carbonitrile 6. Compound 3 reacted with ethyl acetoacetate in refluxing acetic acid and in presence of ammonium acetate to yield the indolylpyridine 10. Enamine 3 reacted with 5(1H)‐aminotriazole 13 and 3(5)‐aminopyrazole 17 to yield the pyrimidine derivatives 15 and 19, respectively.
Microwave‐induced perchloric acid catalyzed novel solvent‐free synthesis of 4‐aryl‐3,4‐dihydropyrimidones via biginelli condensation
Authors: Mukhopadhyay Chhanda , Datta Arup , Banik Bimal K. 
Published: March 2009

Abstractmagnified imageWe report here domestic microwave‐induced perchloric acid‐catalyzed solvent‐free synthesis of various 4‐aryl‐3,4‐dihydropyrimidones for the first time. In all the cases the yields are excellent and the mechanism follows a simple Biginelli condensation to produce the dihydropyrimidones in a few seconds. This procedure has been successfully employed to synthesize the mitotic kinesin EG5 inhibitor Monastrol (Figure I).
Pyrolytic behavior of substituted N‐aminoheteroaromatics: Synthesis of pyrazolo[1,5‐a]pyridine and 3‐substituted 3‐oxopropionitrile derivatives
Authors: Al‐Awadi Nouria A. , Patel Mehul , Dib Hicham H. , Abdelkhalik Mervat 
Published: March 2009

Abstractmagnified imageFlash vacuum pyrolysis (FVP) of 1,7‐bis‐(3‐aroylideneamino)‐4,6,10,12‐tetramethyl‐2,8‐dioxo‐1,7‐diazacyclododeca‐3,5,9,11‐tetraene‐3,9‐dicarbonitriles 11a‐c at 650°C and 0.02 Torr yielded 5,7‐dimethyl‐3‐(4‐methylbenzoyl)‐pyrazolo[1,5‐a]pyridine‐4‐carbonitrile 14, 4,6‐dimethyl‐2‐oxo‐1,2‐dihydropyridine‐3‐carbonitrile 16 and 3‐aryl‐3‐oxo‐propionitriles 17a,b. A plausible mechanism is suggested to account for the formation of the products.
A convenient route to synthesize 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives and their one and two‐photon absorption spectral properties
Authors: Wang Hongli , Xu Wenyuan , Dai Yi , Zhang Bin , Wu Qiongyou , Zhang Mingzhi , Tian Min , Wu Hong , Wang Dingli 
Published: March 2009

Abstractmagnified imageA convenient method for synthesizing α‐(1,2,4‐triazolo[1,5‐a]pyrimidine‐2‐sulfonyl)methane derivatives, 3 and 4, by the well known Knoevenagel reaction, in one step, is described. The two chromophores are stilbene‐type chromophores containing the same D‐π‐A structures and end‐capped with aromatic group as their donors. Measured with femtosecond multipass Ti:sapphire amplifier as irradiation source (pumped by the laser at 800 nm), the two chromophores show efficient two‐photon induced orange red fluorescence emission. The experimental results indicate that the numbers of branches of the two chromophores affect their one‐photon properties and two‐photon up‐conversion emission behaviors, and with the increasing numbers of branches, their wavelengths of λabsmax, λspfmax and λtpfmax exhibit bathochromic shifts.
A novel synthesis of cyclopropyl lactam and amide from cis‐2‐aryl‐3‐benzoyl‐1,1‐dicynocyclopropane with H2O2 in the presence of NaHCO3
Authors: Ren Zhongjiao , Chen Jie , Lu Yeying , Wu Danyi , Cao Weiguo 
Published: March 2009

Abstractmagnified imageThe process for preparation of cyclopropyl lactam and amide from cis‐2‐aryl‐3‐benzoyl‐1,1‐dicynocyclopropane with H2O2 in the Presence of NaHCO3 is described. The highly stereoselective conversion of monocyano group to amide has been carried out in the present method.
Transformations of phenylhydrazones of 5‐acyl‐1,2,4‐triazines to pyrazolo[4,3‐e][1,2,4]triazines or 4‐cyanopyrazole
Authors: Mojzych Mariusz , Rykowski Andrzej 
Published: March 2009

Abstractmagnified imageA simple and high yielding preparation of pyrazolo[4,3‐e][1,2,4]triazines and 4‐cyano‐3‐methyl‐1‐phenylpyrazole derivatives from corresponding phenylhydrazones of 5‐acyl‐1,2,4‐triazines by melt under acidic medium and by thermal heating, respectively.
Synthesis and crystal structure of novel schiff bases derived from 3‐(2‐ethoxyphenyl)‐4‐amino‐5‐mercapto‐4H‐1,2,4‐triazole
Authors: Zhou San‐nu , Zhang Li‐xue , Zhang An‐jiang , Sheng Ji‐shun , Zhang Hai‐le 
Published: March 2009

Abstractmagnified imageA series of novel 4‐(arylmethylidene)amino‐5‐(2‐ethoxyphenyl)‐3‐mercapto‐4H‐1,2,4‐triazoles (2a‐f) were easily synthesized in high yields by means of the reactions of 3‐(2‐ethoxyphenyl)‐4‐amino‐5‐mercapto‐4H‐1,2,4‐triazole (1) with various aromatic aldehydes. The compound, 4‐(4‐methylbenzylidene)‐amino‐5‐(2‐ethoxyphenyl)‐3‐mercapto‐4H‐1,2,4‐triazole was investigated with X‐ray crystallography.
Synthesis and antifungal activity of novel 3,6‐diaryl‐5H‐[1,2,4]triazolo[4,3‐b][1,2,4]triazepines
Authors: Gupta Monika 
Published: March 2009

Abstractmagnified image5‐Aryl‐3,4‐diamino‐1,2,4‐triazoles 5 on treatment with β‐chlorocinnamaldehydes 7 in the presence of catalytic amount of p‐TsOH and N,N‐dimethylformamide as an energy transfer medium under microwave irradiation and as solvent with oil‐bath heating at 80 °C affords novel 3,6‐diaryl‐5H‐[1,2,4]triazolo[4,3‐b]‐1,2,4]triazepines 8. The structures of the synthesized compounds were established on the basis of 1H NMR, IR, mass spectral data and elemental analysis.
Ring transformations of heterocyclic compounds. XXV. Phenanthrene aldehyde imines via ring transformation of pyrylium salts with methylenedihydroisoquinolines—A novel access to the phenanthrene skeleton
Authors: Zimmermann Thomas , Krautscheid Harald 
Published: March 2009

Abstractmagnified imageThe ring transformation of 2,4,6‐triarylpyrylium salts 1 with 2‐methylenedihydroisoquinolines 6, generated in situ from the related 2‐methylisoquinolinium salts 2, in the presence of bases is reported. Whereas the transformation of 1 with 2(6) and sodium methoxide in methanol leads to 2‐(2,4,6‐triarylphenyl)isoquinolinium salts, with sodium ethoxide in ethanol the aryl substituted phenanthrene‐9‐carbaldehyde imines 4 are obtained, the structure of which was confirmed by an X‐ray structure determination of the 1‐(4‐methylphenyl) substituted derivative. Acid catalyzed hydrolysis of the imines 4 gives rise to the parent phenanthrene aldehydes. The transformation 1 + 2(6) → 4 represents a novel access to the phenanthrene skeleton.
Synthesis of new chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines
Authors: Martínez‐Viturro Carlos M. , Domínguez Domingo 
Published: March 2009

Abstractmagnified imageThe total synthesis of chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines from easily prepared 4‐methoxy‐1‐nitro‐9H‐xanthen‐9‐one is reported. These compounds, in which a 1,3‐diazine ring is fused to the xanthene scaffold, were obtained with good overall yields in very few steps.
1,3‐dipolar cycloadditions. Part XII ‐ selective cycloaddition route to 4‐nitroisoxazolidine ring systems
Authors: Banerji Avijit , Gupta Maya , Biswas Pizush Kanti , Prangé Thierry , Neuman Alain 
Published: March 2009

Abstractmagnified imageCycloadditions of C,N‐diarylnitrones to β‐nitrostyrenes occurred to yield two diastereoisomeric cycloadducts, the 3,4‐trans‐4,5‐trans substituted isoxazolidine derivatives being formed selectively as the major products. These were characterised by spectroscopic and X‐ray data. Conformational studies were carried out by X‐ray crystallography and Molecular Modelling.
Reactions of some pyrrole‐2,3‐diones with hydrazine hydrate and o‐phenylenediamine
Authors: Sarıpınar Emin , Karataş Süleyman , İlhan İlhan Özer 
Published: March 2009

Abstractmagnified image2,3‐Dihydro‐1H‐pyrrole‐2,3‐diones 1a‐d react with hydrazine hydrate 2 and o‐phenylenediamine 4 under different conditions to yield the pyrazole‐3‐carboxamide derivatives 3a‐d, the pyrrol‐2‐ones 5a‐d and the quinoxaline‐2‐one derivatives 6a‐d, respectively. Hydrolysis of the quinoxaline‐2‐one derivatives 6a‐d gave a substituted furo[2,3‐b]quinoxaline 7. The structures of the synthesized compounds were assigned on the basis of analytical results as well as spectroscopic data.
A rapid synthesis of new benzene‐centered porphyrin trimers
Authors: Papamicaël Cyril A. , Mongin Olivier , Gossauer Albert 
Published: March 2009

Abstractmagnified imageIn connection with our study of the capability of forming ordered self‐assembled monolayers on gold substrates, we described the full details concerning the rapid synthesis of two rigid, star‐shaped D3‐symmetric arrays with a benzene core attached to three identical metalloporphyrins containing either ethyldisulfide functions or thienyl groups.
Chemo, stereo, and regioselective addition of α‐(2‐methoxyaryl)‐N‐aryl nitrones to diarylidineacetone: Synthesis of novel isoxazolidines
Authors: Jayapradha Sadaiyan Ramadass , Sridharan Vellaisamy , Muthusubramanian Shanmugam , Polborn Kurt 
Published: March 2009

Abstractmagnified imageA new set of 2,3,4,5‐tetrasubstituted isoxazolidines with an α,β‐unsaturated carbonyl function at position 4 has been synthesized. The multicomponent approach and microwave irradiation protocol have also been investigated for the above synthesis.
Regioselective synthesis of polyheterocyclic scaffolds by sequential [3,3] sigmatropic rearrangements and pyridine hydrotribromide mediated heterocyclization
Authors: Majumdar K. C. , Muhuri S. 
Published: March 2009

Abstractmagnified imageA number of tetracyclic polyhetero scaffolds have been regioselectively synthesised in 70‐75% yield from 4‐[(3‐aryloxy‐2‐propynyl)oxy]‐6‐methyl‐pyran‐2‐ones via thionation of the lactone carbonyl, sequential Claisen rearrangements and pyridine hydrotribromide mediated heterocyclization.
Base‐promoted rearrangements of ester groups in 3a,7a‐dihydroindole‐2,3,3a,4‐tetraester
Authors: Jeon Kyu Ok , Yu Ji Sook , Lee Chang Kiu 
Published: March 2009

Abstractmagnified imageTetramethyl 3a,7a‐dihydro‐1‐methyl‐1H‐indole‐2,3,3a,4‐tetracarboxylate which is an 1:2 adduct of 1‐methylpyrrole and dimethyl acetylenedicarboxylate underwent isomerization catalyzed by sodium methoxide to form a 5,7a‐dihydro‐1‐methyl‐1H‐indole‐2,3,4,5‐tetracarboxylate, its 5,6‐dihydro isomer, and a ring opening product which is an azonine derivative. Fully aromatized esters such as 1‐methylindole‐2,3,4‐triester, 1‐methylindole‐2,3,4,5‐tetraester and 1‐methyl‐2,3,4,6‐tetraester were also isolated. An indole compound which could be formed by conjugative addition of the methoxide ion was also isolated.
Synthesis of 2‐formyl‐1‐aza‐dibenzo[e,h]azulenes
Authors: Pešić Dijana , Landek Ivana Ozimec , Čikoš Ana , Metelko Biserka , Gabelica Vesna , Stanić Barbara , Merćep Mladen , Mesić Milan 
Published: March 2009

Abstractmagnified imageSynthesis of a novel heterocyclic class of compounds, 1‐aza‐dibenzo[e,h]azulenes [1] (6a‐c and 7a‐c), derived from dibenzo[b,f]oxepin, its 8‐chloro analogue and dibenzo[b,f]thiepin, respectively, is described. Aldol condensation of the starting ketones 4a‐c with (dimethyl‐hydrazono)‐acetaldehyde affords hydrazonoethylidene derivatives 5a‐c, which on reduction with sodium dithionite and subsequent cyclization provide the target tetracyclic 1‐aza‐dibenzo[e,h]azulenes 6a‐c. Regiospecific formylation of 6a‐c with Vilsmeier reagent leads to 2‐formyl derivatives 7a‐c. A series of derivatives 6a‐c and 7a‐c was tested for antiinflammatory activity as potential inhibitors of tumor necrosis factor alpha (TNF‐α) production in vitro.
A revised synthetic scheme of 6,6′‐dibromoindirubin
Authors: Tanoue Yasuhiro , Hara Akari , Kai Norihisa , Sakata Kazunori , Hashimoto Mamoru , Nagai Takeshi 
Published: March 2009

Abstractmagnified imageThe synthetic scheme of 6,6′‐dibromoindirubin (2) was investigated in detail. The reaction of 6‐fluoro‐3‐acetoxyindole (7) with isatin (8) in methanol with Na2CO3 produced 6′‐fluoroindirubin in moderate yields. Its structure determination was mainly undertaken using 1H NMR spectroscopy. On the basis of this result, the synthetic scheme of 2 reported by Cooksey was revised.
Pyrazolo[4′,3′:5,6]pyrano[2,3‐b]quinoxalin‐4(1H)‐one: Synthesis and characterization of a novel tetracyclic ring system
Authors: Eller Gernot A. , Datterl Barbara , Holzer Wolfgang 
Published: March 2009

Abstractmagnified imageDerivatives of the hitherto unknown ring system, pyrazolo[4′,3′:5,6]pyrano[2,3‐b]quinoxalin‐4(1H)‐one, are synthesized in one step from the corresponding 1‐substuituted or 1,3‐disubstituted 2‐pyrazolin‐5‐ones and 3‐chloroquinoxaline‐2‐carbonyl chloride using calcium hydroxide in boiling 1,4‐dioxane. The parent system carrying no substituent in positions 1 and 3 is obtained upon treatment of the 1‐PMB (p‐methoxybenzyl) protected congener with trifluoroacetic acid. Detailed NMR spectroscopic investigations including unambiguous chemical shift assignments of all 1H, 13C, and 15N resonances of the obtained tetracycles are reported.
Synthesis and physicochemical properties of new 1N o‐(m‐ and p‐) bromobenzyl substituted derivatives of 5‐(aminodialkyl)methylcytosine
Authors: Prukala Dorota 
Published: March 2009

Abstractmagnified imageSimple alkylation of 5‐(aminodialkyl)methylcytosine a‐d gives twelve new, potentially biologically active 1N o‐(m‐ or p‐) bromobenzyl derivatives of 5‐substituted cytosine 1‐12 with high regioselectivity. The structures of all compounds have been confirmed by elemental analysis, IR, 1H NMR and 13C NMR spectroscopic measurements.
Oxidation of N‐heterocyclics: A green approach
Authors: Sivasubramanian Ganarajan , Parameswaran Veembil Ramachandran 
Published: March 2009

Abstractmagnified imageEnvironmentally benign oxidation methods satisfy the postulates of green chemistry. Heterocyclic Noxides have applications in synthetic organic chemistry, chemotherapy and agrochemicals. Synthesis of Noxides using green oxidants will be attractive over the conventional methods. The presence of the N‐oxide group in the azine ring makes it more subject to electrophilic and nucleophilic attack and substantially expands the synthetic approaches for the modification of nitrogen‐containing heterocyclics. That is the reason for the increasing interest in the chemistry of heterocyclic N‐oxides. Some reactions adopted for oxidation of N‐heterocyclics have been discussed. Stereochemical and spectroscopic aspects have been mentioned. It will be advantageous if anchored catalysts are employed for industrial exploitation. Several physiochemical aspects of various methods have been discussed.
Synthesis, oxidation and dehydrogenation of cyclicN,O‐ andN,S‐acetals. Part III. Transformation ofN,O‐acetals: 3‐acyl‐1,3,4‐oxadiazolines
Authors: Somogyi László 
Published: March 2009

Abstractmagnified imageVarious aldehyde and ketone acylhydrazones are synthesized and, under acylating conditions, cyclized into 3‐acyl‐1,3,4‐oxadiazolines. The scope and limitations of these cyclizations and the possible side reactions (e.g. formation of the open‐chainN,O‐acylhydrazinocarbinols) are dissected. For the first time, simple, convenient and efficient dehydrogenations of 3‐acyl‐1,3,4‐oxadiazolines to oxadiazoles by treatment with potassium permanganate, or more conveniently, with ammonium cerium(IV) nitrate (CAN) are presented. CAN oxidation of 2,2‐disubstituted 3‐acyl‐1,3,4‐oxadiazolines, as well as that of aldehyde diacylhydrazones (open‐chain isomers of 2,5‐disubstituted 3‐acyl‐1,3,4‐oxadiazolines) regenerates the parent carbonyl compounds.