bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the basicity of some 1,2‐diazinium ylids
Authors: Caprosu M. , Roman M. , Olariu I. , Dima S. T. , Mangalagiu I. , Petrovanu M. 
Published: March 2009

AbstractIn this paper we present a study concerning the basicity of some new carbanion monosubstituted pyridazinium, 3‐methyl‐pyridazinium, 3‐(p‐halogenophenyl)‐pyridazinium and phtalazinium ylids. The pka values of the conjugated acids (salts) of ylids have been experimentaly determinated. Consequently, we have evaluated their basicity (kb,) using the titration curves. The basicity depends mainly on the structure of the ylids carbanion itself, however the heterocycle's structures also has some influence on bacisity. Having in view the basicity, we have established certain correlations between basicity, structure and stability of the analised ylids.
Hypervalent iodine in synthesis 50: A novel method of synthesis of selenazoles by cyclocondensation of selenoamides and alkynyl(phenyl)iodonium salts
Authors: Zhang Peng‐Fei , Chen Zhen‐Chu 
Published: March 2009

AbstractA novel method for the synthesis of selenazoles by cyclocondensation of primary selenoamides and alkynyl(phenyl)iodomium salts and the reaction mechanism are reported. The synthetic method is simple, mild and the yields are high.
Diastereoselective synthesis of (2R,4S,5S)‐(+)‐5‐(2,2‐dichloroacetamido)‐ 4‐(4‐nitrophenyl)‐2‐aryl‐1,3‐dioxanes
Authors: Jun Liu , Jun Li , Shaorong Yang , Hua Li , Quanyuan Hu , Hansheng Xu , Xianming Hu 
Published: March 2009

Abstract(2R,4S,5S)‐(+)‐5‐(2,2‐Dichloroacetamido)‐4‐(4‐nitrophenyl)‐2‐aryl‐1,3‐dioxanes 3–8 were synthesized with high diastereoselectivity and good yields. The structures of acetals were determined and the configurations were confirmed by 2D‐NMR (NOESY) and X‐ray crystallographic analysis.
Synthesis of fused pyrimidines with N‐, S‐heterocyclic moieties by double‐annelation reaction
Authors: Chowdhury A. Z. M. Shaifullah , Shibata Yasuyuki 
Published: March 2009

AbstractA variety of tri‐ and tetracyclic hetero systems were obtained by reaction of heteroaromatic ortho‐aminoesters or ortho‐aminonitriles with iminothioether, yielding double‐annelation of a thiazolo[3,2‐a]‐pyrimidine, pyrimido[2,l‐b]thiazine, imidazo[1,2‐a]pyrimidine, and pyrimido[1,2‐a]pyrimidine moieties in a one‐pot process.
Photoinduced molecular rearrangements. Some comments on the ring‐photoisomerization of 1,2,4‐oxadiazoles into 1,3,4‐oxadiazoles
Authors: Buscemi Silvestre , Pace Andrea , Vivona Nicolò , Caronna Tullio 
Published: March 2009

AbstractThe ring‐photoisomerization of 3‐amino‐ and 3‐methylamino‐5‐phenyl‐1,2,4‐oxadiazoles into the corresponding 2‐amino‐ and 2‐methylamino‐5‐phenyl‐1,3,4‐oxadiazoles has been reinvestigated by examining the effect of a base on the photoreaction. On irradiating at λ = 254 nm in methanol, yields of the ring‐photoisomers were found to be significantly enhanced by the addition of triethylamine (TEA) in the photoreaction medium. By contrast, irradiation of the 3‐amino‐5‐phenyloxadiazole in acetonitrile containing TEA gave an almost complete photoreduction into benzoylguanidine, while few percent of the ring photoisomer were detected. Furthermore, the pyrene‐sensitized photolysis of 3‐amino‐5‐phenyloxadiazole in acetonitrile containing triethylamine also gave benzoylguanidine but no traces of the ring photoisomer.
An easy route to 2‐substituted‐2,3‐dihydro‐5(7)H‐oxazolo[3,2‐a]pyrimidin‐5‐ones and 7‐ones starting from the corresponding 2‐amino‐2‐oxazolines
Authors: Forfar I. , Guillon J. , Massip S. , Léger J.‐M. , Jarry C. , Fayet J.‐P. 
Published: March 2009

AbstractThe isomeric 2‐substituted‐7(5)‐methyl‐2,3‐dihydro‐5(7)H‐oxazolo[3,2‐a]pyrimidin‐5‐ones 3a‐b and 7‐ones 2a‐b,7a were synthesized by cyclocondensation from the 5‐substituted‐2‐amino‐2‐oxazolines 1a‐b with biselectrophiles. In boiling ethanol, the reaction of 1a‐b with acetylenic esters led to a mixture of 2a‐b,7a with a small amount of (E)‐2‐N‐(2‐ethoxycarbonylethylene)‐5‐substituted‐2‐iminooxazolines 5a‐b. The ring annulation between 1a‐b and diketene gave the 2‐substituted‐7‐hydroxy‐7‐methyl‐2,3,6,7‐tetrahydro‐5H‐oxazolo[3,2‐a]pyrimidin‐5‐ones 4a‐b which can be easily dehydrated to provide the 2‐substituted‐7‐methyl‐2,3‐dihydro‐5H‐oxazolo[3,2‐a]pyrimidin‐5‐ones 3a‐b.
Synthesis and NMR spectroscopic studies of optically active derivatives of γ‐aminobutenoic acids and 2‐amino‐pyrrolin‐4‐ones
Authors: Petroliagi Margarita , Igglessi‐Markopoulou Olga 
Published: March 2009

AbstractAn efficient method for the preparation of optically active derivatives of γ‐amino‐butenoic acids and their cyclic derivatives, 2‐amino‐pyrrolin‐4‐ones, from α‐amino acids is described. Partial racemization accompanies the formation of initial unsaturated γ‐amino‐β‐hydroxy esters 5–8, as determined by chiral HPLC.
An improved synthesis of enantiomerically pure RWJ 69442, a development candidate for the treatment of benign prostatic hyperplasia
Authors: Kuo Gee‐Hong , Prouty Catherine , Murray William V. , Shah Rekha D. 
Published: March 2009

AbstractThis report describes an improved synthesis of enantiomerically pure (S)‐2‐[4‐(Dimethylamino)phenyl]‐2,3‐dihydro‐N‐[2‐hydroxy‐3‐[4‐[2‐(1‐methylethoxy)‐phenyl]‐1‐piperazinyl]propyl]‐1,3‐dioxo‐1H‐isoindole‐5‐carboxamide (RWJ 69442), a potent and selective αla‐adrenergic receptor antagonist for the treatment of benign prostatic hyperplasia. The synthesis highlights less hazardous reagents, easier purification and higher enantiomeric purity. The N‐benzyl‐N—t‐butoxycarbonyl amine 6 could serve as an enantiomerically pure chiral building block for asymmetric synthesis.
On the mechanism and stereochemistry of the formation of β‐lactam derivatives of 2,4‐disubstituted‐2,3‐dihydro‐benzo[1,4]diazepines
Authors: Wang Hong‐Zhong , Zhou Xin , Xu Jia‐Xi , Jin Sheng , Li Yue‐Ming , Chan AlbertS. C. 
Published: March 2009

Abstract2‐Chloro‐4‐phenyl‐2a‐(4′‐methoxyphenyl)‐3,5‐dihydroazatetracyclic [1,2‐d]benzo [ 1,4]diazepin‐1 ‐one (IIIa) and 2‐chloro‐4‐methyl‐2a‐(4′‐methoxyphenyl)‐3,5‐dihydroazatetracyclic[1,2‐d]‐benzo[1,4]diazepin‐1‐one (IIIb) were synthesized. 1‐Benzoyl‐2‐phenyl‐4‐(4′‐methoxyphenyl)[1,4]‐benzodiazepine (IIa) was formed through benzoylation of starting material 2‐phenyl‐4‐(4′‐methoxyphenyl)‐[1,4]benzodiazepine (Ia) with the inversion of seven‐member ring boat conformation. The thus formed β‐lactams should have four pairs of stereoisomers. However, only one pair of enantiomers (2S,2R,4R) and (2R,2aS,4S) was obtained. The mechanism and stereochemistry of the formation of these compounds were studied on the basis of nmr spectroscopy and further confirmed by X‐ray diffraction.
The synthesis of 1‐[(substituted)pyrazol‐5‐yl]‐iminomethyl‐2‐nitroiminoimidazolidine and its derivatives
Authors: Chen Wei‐Qiang , Ji Gui‐Yu 
Published: March 2009

AbstractIn this article 1‐[(substituted)pyrazol‐5‐yl]iminomethyl‐2‐nitroimino imidazolidines (II) and their derivatives were synthesized. All the compounds were verified by elemental analysis, 1H NMR and IR. In the reaction of II with halides, two different results were observed.
Investigation the chemical reactivity of positions N‐3, C‐5 and C6‐methyl group in biginelli type compounds and synthesis of new dihydropyrimidine derivatives
Authors: Mirzaei Y. R. , Azamat H. , Namazi H. 
Published: March 2009

AbstractThe compounds 5‐ethoxycarbonyl‐1,6‐dimethyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(lH)‐one (5) and 5‐ethoxycarbonyl‐1‐phenyl‐6‐methyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(lH)‐one (1) were prepared by the Biginelli condensation method and they converted to eight N‐3 substituted dihydropyrimidines using NaH and various electrophiles (ClCO2Et, TsCl, Ac2O, AcCl and PhCOCl). Compound (1) was mono‐brominated at the C6‐methyl group using bromine solution. Reaction of the bromo derivative with amino nucleophiles such as methyl amine and cyclohexyl amine produced two pyrrolo‐pyrimidine derivatives. All the compounds except 5‐ethoxycarbonyl‐1‐phenyl‐6‐methyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(lH)‐one (4) were purified by recrystallization methods. The structure of all the new compounds was confirmed using FT‐ir,1H nmr,13C nmr spectral and elemental analyses methods.
Synthesis of new heterocondensed pteridines
Authors: Chowdhury A. Z. M. Shaifullah , Shibata Yasuyuki , Morita Masatoshi , Kaya Kunimitsu , Hiratani Kazuhisa 
Published: March 2009

AbstractReaction of 2‐aminopyrazine 1 with isothiocyanate, isocyanate or dithioketal reagent furnished pteridines 3,4 in good yield. Thioxo compound 3a was chlorinated, methylated and subsequently displaced by amines. A simple one‐step synthesis of heterocondensed pteridines 8–13 by reaction of 2‐aminopyrazine with various imino thioacetals was described 8–13.
The reaction of homophthalic acid and some aza analogues with vilsmeier reagent: a reinvestigation
Authors: Deady Leslie W. , Rodemann Thomas 
Published: March 2009

AbstractHomophthalic acid and its pyrido and 8‐methylquinolino analogues with dimethylformamide/phosphoryl chloride at 0° give the appropriate 4‐(dimethylaminomethylene)isochroman‐1,3‐dione (2a, 2b, 2c, respectively). Under the literature conditions for conversion of 2a to 2‐methyl‐1‐oxo‐1,2‐dihydroisoquinoline‐4‐carboxylic acid (3a), the aza analogues give instead 7‐hydroxy‐5‐oxo‐5H‐pyrano[4,3‐b]pyridine‐8‐carbox‐aldehyde (5b) and 3‐hydroxy‐6‐methyl‐1‐oxo‐1H‐pyrano[4,3‐b]quinoline‐4‐carboxaldehyde (5c), respectively. Modified conditions were required to isolate analogues 3b and 3c. Further, while reaction of 2a with hydrogen chloride in methanol gave the known change to methyl 1‐oxo‐1H‐isochromene‐4‐carboxylate (4), 2b and 2c gave only products of oxa‐ring cleavage. Methyl 2‐(cis‐2‐hydroxyvinyl)‐8‐methylquinoline‐3‐carboxylate (8) was the main product from 2c, while a novel quinolizinium species (11) was formed in good yield from 2b.
Synthesis and characterization of some coumarins with two hydroxy or methoxy substituents
Authors: Fall Yagamare , Santana Lourdes , Uriarte Eugenio 
Published: March 2009

AbstractThe first synthesis of the 6‐hydroxy‐4‐methoxycoumarin (5) was carried out in 25 % overall yield from 6‐methoxy‐4‐hydroxycoumarin (1) by hydrolysis of the methoxy group and subsequent selective methylation of the hydroxyl group at position 4. The 1H and 13C NMR data of compounds 1–6 are reported.
Ring transformations of heterocyclic compounds. XXI. Diastereoselective built‐up of an aroylcyclohexadiene moiety as second spiro‐connected ring at spiroindolines by pyrylium ring transformation
Authors: Zimmermann Thomas 
Published: March 2009

Abstract2,4,6‐Triarylpyrylium perchlorates 1 react with methyleneindolines 3 in situ generated from the corresponding methylindolium salts 2, which are spiro‐fused with a cycloalkane, benzanellated cycloalkene or a heterocyclic system. These diastereoselective 2,5‐[C4+C2] pyrylium ring transformations are carried out in the presence of triethylamine/acetic acid in boiling ethanol to give the dispiroindolines 4 with a trans configuration of the more bulky substituents at the cyclohexadiene ring. By the same type of transformation the dispiro compounds 7/10 with an additional fused benzene ring are obtained from the pyrylium salt 1a and 6/9, the benzo‐fused analogues of 3. Spectroscopic data of the transformation products as well as their mode of formation are discussed.
A convenient synthesis of 5‐ and 8‐nitroquinazoline‐2,4‐dione derivatives
Authors: Aziane D. , Soukri M. , El Hakmaoui A. , Lazar S. , Akssira M. , Essassi E. M. , Guillaumet G. 
Published: March 2009

Abstract3‐Nitrophthalic acid 1 was converted selectively to the two regioisomeric monoesters 2 and 3, which were subsequently transformed via Curtius rearrangement to the corresponding 5‐ and 8‐nitroquinazoline‐2,4‐diones 4 and 5, respectively. The reduction of the nitro group produced 5‐ and 8‐aminoquinazoline‐2,4‐diones 6 and 7, respectively, in good yields. The condensation of compounds 7b and 7c with carbon disulfide in pyridine afforded tricyclic derivatives 9, which are analogues of the HIV‐1 reverse transcriptase inhibitor 4,5,6,7‐tetrahydro‐5‐methylimidazo[4,5,1‐jk][1,4]benzodiazepin‐2(1H)‐one(TIBO).
Synthesis of spirolactones by 1,3‐dipolar cycloadditions to methyl (S)‐3‐[(E)‐cyanomethylidene]‐2‐oxotetrahydrofuran‐5‐carboxylate
Authors: Pirc Samo , Rečnik Simon , Škof Marko , Svete Jurij , Golič Ljubo , Meden Anton , Stanovnik Branko 
Published: March 2009

AbstractDedicated to Professor Emeritus Miha Tišler on the occasion of his 75th birthdayTreatment of methyl (S)‐5‐[(E)‐(dimethylamino)methylidene]‐2‐oxotetrahydrofuran‐5‐carboxylate (2) with potassium cyanide in acetic acid gave (S)‐5‐[(E)‐cyanomethylidene]‐2‐oxotetrahydrofuran‐5‐car‐boxylate (3), which was used as chiral dipolarophile in 1,3‐dipolar cycloadditions. Reactions of 3 with diazomethane (4) and nitrile oxides 5a‐c afforded spirolactones 6–8 in 24‐34% diastereomeric excess, while with diazomethane (4) in the presence of triethylamine, methyl 3‐cyanomethyl‐2‐methoxyfuran‐5‐carboxylate (12) was obtained.
A comparative study on the synthesis of 4‐alkyl‐1,3‐diarylpyrazoles using microwave irradiation and conventional thermal methods
Authors: Selvi S. , Perumal P. T. 
Published: March 2009

AbstractA convenient synthesis of 4‐alkyl‐1,3‐diarylpyrazoles (2) under microwave irradiation as well as conventional thermal method using Vilsmeier cyclization is reported. Microwave irradiation has resulted in the reduction of time from hours to seconds.
Study of the heterocyclization of vic‐substituted hydrazides of acetylenylpyrazolecarboxylic acids into N‐amino pyrazolopyridinones
Authors: Vasilevsky Sergei F. , Mshvidobadze Elena V. , Elguero José 
Published: March 2009

AbstractWe report a new and efficient methodology to prepare N‐amino pyrazolo[4,3‐c]pyridin‐4‐ones 4 and N‐amino pyrazolo[3,4‐c]pyridin‐4‐ones 8 from vic‐acetylenyl/hydrazido pyrazoles. The procedure involves the intermediate synthesis of methyl esters of acetylenyl‐pyrazole carboxylic acids and the subsequent cyclization under a variety of conditions.
Tautomerism of diazepines fused with pyrimidine rings
Authors: Chebanov Valentin A. , Desenko Sergey M. , Shishkin Oleg V. , Kolos Nadezhda N. , Komykhov Sergey A. , Orlov Valery D. , Meier Herbert 
Published: March 2009

AbstractThe tautomerism of 1,4‐diazepines fused with pyrimidine rings was studied by means of nmr spec‐troscopy, X‐ray analysis and quantum chemical calculations. It was found that in the case of 6,8‐diphenyl‐pyrimido[4,5‐b][1,4]diazepin‐4‐ols (7a ‐ e) the enamine form is more stable than the diimine form. This result is rationalized with the electron‐withdrawing effect of the 4‐hydroxypyrimidine ring and with the formation of intermolecular hydrogen bonds. In contrast to 7a ‐ e, the 6,8‐diaryl‐2,3,4,7‐tetrahydro‐1,3‐dimethyl‐1H‐pyrimido[4,5‐b][1,4]diazepine‐2,4‐diones (9a, c, f) exist in the diimine form.
Synthesis and 1,3‐dipolar cycloaddition reactions of N‐Aryl‐C, C‐dimethoxycarbonylnitrones
Authors: Tomioka Yukihiko , Nagahiro Chie , Nomura Yumiko , Maruoka Hiroshi 
Published: March 2009

AbstractArylnitroso compounds 1–3 easily reacted with dimethyl bromomalonate to give the corresponding N‐aryl‐C,C‐dimethoxycarbonylnitrones (4–6). Treatment of C,C‐dimethoxycarbonyl‐N‐( 1‐naphthyl)nitrone (4) with acetylene compounds (dimethyl acetylenedicarboxylate, methyl 2‐butynoate or ethyl phenylpropiolate) caused 1,3‐dipolar cycloaddition to furnish the corresponding 1H‐benz[g]indolines (7a‐c). In a similar manner, the reactions of nitrones 5 and 6 with acetylene compounds afforded the corresponding indolines 9a‐c and 11a‐c together with 4‐oxazolines 13a‐c and 14a‐c.
Structural Aspects of 5‐methylthio‐1‐oxa‐6,6a δIV‐dithia‐2‐azapentalenes
Authors: Chollet‐Krugler Marylégne , Burgot Jean‐Louis , Finner E. , Christen Marie‐Odile 
Published: March 2009

AbstractAlkylation of 5‐[1‐hydroxyiminoalkyl]‐1,2‐dithiole‐3‐thiones using methyl iodide in the presence of sodium hydroxide gives derivatives which may be considered as being 5‐methylthio‐1‐oxa‐6,6a δIV‐dithia‐2‐azapentalenes with quantitative yields. The structure of oxadithiazapentalene attributed to the alkylation products is founded on X‐ray analysis and NMR and IR data.
Synthesis of new uracil non‐nucleoside derivatives as potential inhibitors of HIV‐1
Authors: El‐Essawy Farag A. , El‐Brollosy Nasser R. , Pedersen Erik B. , Nielsen Claus 
Published: March 2009

Abstract6‐(2‐Phenylethyl) and 6‐cyclohexyl 5‐cyanouracils (1a,b) were synthesized and reacted with chloromethyl ethyl ether, benzyl chloromethyl ether, chloromethyl methyl sulfide and (2‐acetoxyethoxy)methyl bromide. New uracil analogues of (S)‐DHPA were synthesized by reaction of compounds (1a,b) with ((S)‐2,2‐dimethyl‐1,3‐dioxolane‐4‐yl) alkylp‐toluenesulfonate.
Structural study of highly halogenated dihydropyridine derivatives as potential calcium channel modulators
Authors: Suárez Margarita , Salfrán Esperanza , Ochoa Estael , Verdecia Yamila , Alba Livan , Martín Nazario , Seoane Carlos , Martínez‐Alvarez Roberto , De Armas Hector Novoa , Blaton Norbert M. , Peeters Oswald M. , De Ranter Camiel J. 
Published: March 2009

AbstractTwo dihydropyridines endowed with fluorine atoms (3) and fluorine and chlorine atoms (4) have been synthesized and structurally characterized by experimental X‐ray analyses and theoretical calculations at the semiempirical (AMI) and ab initio (HF/6–31G*) levels. The results show that these compounds meet the required criteria to act as potential calcium channel modulators.
Synthesis of pyrazole‐fused heterocycles by thermal rearrangement ofN‐aziridinylimino ketenimines
Authors: Lee Kee‐Jung , Kim Dong‐Wook , Kim Boo‐Geun 
Published: March 2009

AbstractThe reaction ofN‐aziridinylimino carboxamides 11 with a mixture of triphenylphosphine, carbon tetrachloride, and triethylamine in dichloromethane (Appel's condition) provides a new route to pyrazole‐fused heterocycles such as 2,3‐dihydro‐lH‐imidazo[1,2‐b]pyrazoles 15 and 9,10‐dihydro‐47H‐pyrazolo[5,l‐b]‐[1,3]benzodiazepines 17viathe thermal rearrangement of the expectedN‐aziridinylimino ketenimines12.
Evaluation of N‐hydroxymethylphthalimide in alkaline medium: Novel entry to the tricyclic [1,3]oxazepine core via an intramolecular π and O‐cationic cyclization
Authors: Cul Armelle , Pesquet Anthony , Daïch Adam , Chihab‐Eddine Abderrahim , Marchalín Štefan 
Published: March 2009

AbstractFused isoindolo[1,3]benzo(or thieno)oxazepines 8a,b and one of their positional isomers aromatic tricyclic N,O‐acetals 13b are reported to occur efficiently in a three‐step sequence from N‐hydroxy‐methylphthalimide (6). The key step of this methodology is the intramolecular arylation of an endocyclic and/or exocyclic N‐acyliminium cation. The mechanism leading to these species, in particular to a tricyclic lactam 13b, is discussed.
Oxazoline chemistry part III. Synthesis and characterisation of [2‐(2′‐anilinyl)‐2‐oxazolines] and some related compounds
Authors: Button Karen M. , Gossage Robert A. 
Published: March 2009

AbstractThe syntheses and characterisation of a series of chiral and achiral 2‐(aminophenyl)‐2‐oxazolines and some related compounds is reported. All of the derivatives have been produced by a one‐step procedure involving the treatment of isatoic anhydride (i.e.[2H]‐3, 1‐benzoxazine‐[1H‐2,4‐dione:1) or its 5‐chloro analogue with a slight excess of appropriate amino‐alcohols. In most cases, anhydrous ZnCl2is shown to be an effective Lewis acid catalyst for this reaction at reflux temperature in high boiling aromatic solvents (PhCl or PhMe). Oxazolines have been readily formed usingrac‐2‐amino‐1‐butanol, (S)‐phenylglycinol, 2‐methyl‐2‐amino‐1‐propanol and(1S,2R)or(IR,2S)‐cis‐1‐amino‐2‐indanol; yields range from 85% to 22%. The use of aminoalcohols such as 2‐ethanolamine, (±)‐2‐amino‐1‐phenyl‐1‐propanol or 3‐amino‐1‐propanol (to give the corresponding 4,5‐dihydro‐1,3‐oxazine) results in poor yields. The use of other Lewis acid catalysts (silicic acid, Cd(acac)2·2H2O, CuCl2·2H2O, InCl3) or higher temperatures did not improve the yields with these latter two substrates. Benzoxazoles and N‐substituted benzoxazoles can also be obtained in reasonable yields from1using 2‐aminophenol (36%) or 2‐amino‐3‐hydroxypyridine (45%).
Preparation of 3‐(10′‐halo‐9′‐anthracenyl) isoxazolecarboxylic esters
Authors: Han Xiaochun , Twamley Brendan , Natale Nicholas R. 
Published: March 2009

AbstractThe 10‐halo (Cl or Br) anthracene‐9‐nitrile oxides (1a,b) were obtained directly from the treatment of 9‐anthracenylaldoxime with N‐halosuccinimide (NCS or NBS) in DMF. The 3‐(10′‐halo‐9′‐anthracenyl)‐5‐isoxazolecarboxylic esters (5a,b and 6a,b) were prepared via 1,3‐dipolar cycloaddition between the obtained nitrile oxides 1a (or 1b) and two different dipolarophiles: ethyl β‐pyrrolidinocrotonate (an enamine of ethyl acetoacetate) or dimethyl acetylenedicarbox‐ylate (DMAD) respectively. The 10 (or 10′)‐ position of the anthracene in either anthracene‐9‐nitrile oxide or 3‐(9′‐anthracenyl) isoxazole molecules (3,4) is readily halogenated by N‐halosuc‐cinimide in DMF. X‐ray studies showed that 5a possesses two aromatic ring systems that lie at 74.4° from coplanarity. The bond linking the two ring systems is 1.4893(18) Å, indicating only partial conjugation between the two ring systems. The crystal lattice showed unique head‐to‐tail intermolecular stacking of anthracene rings.
Synthesis, characterization and biological activity of bis(3‐Aryl‐1‐hexahydropyrimidinyl)methanes. Novel heterocyclic polyamine derivatives
Authors: Bisceglia Juan Á , García María B. , Massa Rosana , Magri María L. , Zani Mariana , Gutkind Gabriel O. , Orelli Liliana R. 
Published: March 2009

AbstractA method is described for the synthesis of bis(3‐aryl‐1‐hexahydropyrimidinyl)methanes 1, by condensation of N‐aryl‐1,3‐propanediarnines 2 with formaldehyde. The reaction mechanism involves N‐arylhexahydropyrimidines 3 as intermediates. Such compounds can also be prepared efficiently by a methylene exchange reaction between bis‐hexahydropyrimidines 1 and the corresponding diamines 2. The antimicrobial activity of compounds 1 was evaluated by the disk diffusion method and some of them showed moderate to good growth inhibition activity.
The synthesis of 8‐hydroxyquinazoline derivatives and their acid‐base interactions
Authors: Kudelko Agnieszka , Zieliński Wojciech 
Published: March 2009

AbstractThe reaction of N‐(2‐R1‐oxyphenyl)benzimidoyl chlorides with cyanamide derivatives in the presence of titanium tetrachloride as a catalyst has yielded some new 4‐amino‐8‐R1‐oxy‐2‐phenylquinazolines. pKa values have been determined for these compounds and the influence of substituents at the basicity of the parent system has been discussed. Some investigations on the methyl‐quinazolinyl ether cleavage in different medium have been done yielding the appropriate hydroxyquinazoline derivatives. In those cases when the deprotection of 4‐amino‐8‐methoxy‐2‐phenylquinazoline was carried in aqueous acidic solutions, the formation of the hydrolysis products 3,4‐dihydro‐2‐phenyl‐4‐quinazolone derivatives was observed as well.
Tandem Michael‐addition/cyclization synthesis and EGFR kinase inhibition activity of pyrido[2,3‐d]pyrimidin‐7(8H)‐ones
Authors: Boros Eric E. , Thompson James B. , Wood Edgar R. , McDonald O. Bradley , Spitzer Timothy D. , Sefler Andrea M. , Reep Bryan R. 
Published: March 2009

Abstract5‐Methoxy and 5‐anilinopyrido[2,3‐d]pyrimidin‐7(8H)‐ones 2a‐2f were obtained by a tandem Michael addition‐cyclization reaction of methanol and anilines with pyrimidinylpropynoate 5. Methoxy derivative 2a was obtained in 62% yield by treatment of 5 with methanol and potassium carbonate. Anilino derivatives 2b‐2f were prepared in 31–71% yields by reacting 5 with the corresponding anilines in refluxing methanol. This methodology accomplishes Michael‐addition and pyridopyrimidinone ring formation in one‐pot and affords the desired products in reasonable yield without chromatography. Propynoate 5 did not react with 4‐cyanoaniline under these conditions. Reaction of 5 with 2‐aminopyridine gave the unexpected arylpyrido[2,3‐d]pyrimidinone 8 in 58% yield and reaction of 5 with imidazole afforded Michael‐adduct 9 in 69% yield. Compounds 2a and 5 were submicromolar inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase.