bluuebunny/crossref_metadata_2025_split huggingface dataset:
First reactions of dialkoxycarbenium tetrafluoroborates with pyrroles, 5H‐dibenz[b,f]azepines, and electron‐rich arenes
Authors: Pindur U. , Flo C. 
Published: March 2009

AbstractPyrrole (2a) and 2,5‐dimethylpyrrole (2b) react with the dialkoxycarbenium tetrafluoroborates 1a‐1c under kinetic control to yield the corresponding acylpyrrole derivatives. 5H‐Dibenz[b,f]azepine (9a) and the 10,11‐dihydro derivative 9b react only with the most electrophilic of the series of electrophiles tested, namely, diethoxycarbenium tetrafluoroborate (1a), to furnish the corresponding formyl derivatives. Similarly, in arene chemistry, the highly electron‐rich N,N‐dimethylaniline (13a) and 1,3,5‐trimethoxybenzene (13b) are formylated by reaction with 1a.
Synthesis and study of chiral NADH models in the thieno[2,3‐b]pyridine series
Authors: Bench R. , Duflos J. , Dupas G. , Bourguignon J. , Queguiner G. 
Published: March 2009

AbstractThieno[2,3‐b]pyridine derivatives, functionalized on the thiophene ring have been synthesized in two different ways: electrophilic substitution of thieno[2,3‐b]pyridine derivatives or construction of a pyridine ring starting from disubstituted thiophene compounds. The products obtained were used in the synthesis of chiral NADH models.
Approaches to the synthesis of benzo[c]phenanthridines
Authors: Blaskó Gábor , Cordell Geoffrey A. 
Published: March 2009

Abstract6‐Methylbenzo[c]phenanthridine derivatives were synthesized via an established route and their cytotoxic activity determined. Attempts to synthesize benzo[c]phenanthridines lacking the 6‐methyl group via a 2‐ben‐zopyrylium intermediate were unsuccessful.
Tricyclic heteroaromatic systems. 5H‐1,2,3‐triazolo[5,1‐c][1,4]benzodiazepine
Authors: Melani F. , Cecchi L. , Colotta V. , Filacchioni G. 
Published: March 2009

AbstractThe synthesis of the new tricyclic system 5H‐1,2,3‐triazolo[5,1‐c][1,4]benzodiazepine, diaza‐analogue of 5H‐pyrrolo[2,1‐c][1,4]benzodiazepine, which is the common feature of some antitumor antibiotics, is reported. The structure of the new tricyclic system and of some of its key intermediates is assigned by means of a 13C nmr study.
Nitroimidazoles. V. Synthesis of 1‐methyl‐2‐(2‐methyl‐4‐thiazolyl)nitroimidazoles
Authors: Shafiee A. , Shahocini S. 
Published: March 2009

AbstractReaction of readily available 2‐methyl‐4‐formylthiazole (1) with glyoxal and ammonia gave 2‐(2‐methyl‐4‐thiazolyl)imidazole (2). Nitration of 2 with a mixture of nitric acid‐sulfuric acid at 100° yielded 2‐(2‐methyl‐4‐thiazolyl)‐4,5‐dinitroimidazole (3) as the sole reaction product, while nitration at 65° afforded 2‐(2‐methyl‐4‐thiazolyl)‐4‐(or 5)‐nitroimidazole (4). N‐Methylation of compound 4 in the presence of base gave 1‐methyl‐2‐(2‐methyl‐4‐thiazolyl)4‐nitroimidazole (6), whereas N‐methylation with diazomethane afforded 1‐methyl‐2‐(2‐methyl‐4‐thiazolyl)‐5‐nitroimidazole (5). N‐Methylation of compound 3 yielded 1‐methyl‐2‐(2‐methyl‐4‐thiazolyl)‐3,5‐dinitroimidazole (7) in high yield.
Examination of the dipolarophilicity of ethylene and nitrile functions in the cycloaddition of mesitonitrile oxide to isopropylidenemalononitrile
Authors: Lianis P. S. , Rodios N. A. , Alexandrou N. E. 
Published: March 2009

AbstractMesitonitrile oxide reacts with isopropylidenemalononitrile to give mono‐ and bis‐1,2,4‐oxadiazole derivatives 2 and 3 and Δ2‐soxazolines 4 and 5 in moderate yields. The dipolarophilic character of the ethylene and nitrile functions in these cycloadditions is examined.
Synthese de dihydro‐6,7 benzo‐b [1H] azonines par extension de cycle de dihydro‐4,5 benzo‐b [1H] azepines
Authors: Nisole Christian , Uriac Philippe , Huet Jean 
Published: March 2009

AbstractL'addition, suivie d'électrocyclisation, d'acétyléniques activés sur des dihydro‐4,5 benzo‐b [1H] azépines, ènamines hétérocycliques, permet la synthèse de dihydro‐6,7 benzo‐b [1H] azonines dont la structure est établie par spectrométrie de masse, rmn 1H et rmn 13C.Activated acetylenic reagents add to heterocyclic enamines 4,5‐deihydor‐1H‐beenzo[b]azepines and by electrocyclisation, give 6,7‐deihydor1Hbeenzo[b]azepines. The structure of those new heterocycles is demonstrated by mass, 1H and 13C nmr.
3‐Aryl‐5‐[(aryloxy)methyl]‐3‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐2‐methylisoxazolidine derivatives. Synthesis and antifungal activity
Authors: Bennett Grace A. , Swift Patricia A. , Mullen George B. , Allen Stanley D. , Mitchell Jeffrey T. , Jones Wendy E. , Georgiev Vassil St. 
Published: March 2009

AbstractThe synthesis and antifungal activity of a novel series of 3‐aryl‐5‐[(aryloxy)methyl]‐3‐[(1H‐1,2,4‐triazol‐1‐yl)‐methyl]‐2‐methylisoxazolidines are described. The in vitro activity was evaluated in solid agar cultures against a variety of dermatophytes and yeast fungi, while in vivo activity was measured in an immune‐compromised mouse model of systemic candidiasis. The activity of the title series was compared to that of ketoconazole and one derivative, the cis‐3‐(4‐chlorophenyl)‐5‐(4‐chlorophenyloxy)methyl analogue 5f was found to possess a similar potency in the in vivo assay. Structure‐activity relationship correlations are also discussed.
Preparation of azolopyridazinecarboxylic acids
Authors: Heinisch G. , Lötsch G. , Offenberger S. , Stanovnik B. , Tisler M. 
Published: March 2009

AbstractOxidation reactions of various methyl substituted azolopyridazines 2a‐d, 3a‐h, 4a,b were investigated in order to gain access to the title compounds. This procedure was found to be of limited scope affording only the carboxylic acids 5, 7 and 9. A variety of novel azolopyridazinecarboxylic acid methyl esters bearing one or two methoxycarbonyl groups at the pyridazine core 17,18 and 12,14,16, 20, respectively, however, could be prepared by means of a regioselective radical substitution process.
Synthesis and configuration of 4‐alkyl‐2‐methyl‐3,4‐diphenyl‐1,2‐thiazetidine 1,1‐dioxide
Authors: Grander Evelyne , Leclerc Gérard , Ehrhardt Jean‐Daniel 
Published: March 2009

Abstract4‐Alkyl‐2‐methyl‐3,4‐diphenyl‐1,2‐thiazetidine 1,1‐dioxide 5, 6 and 7 were obtained from 2‐methyl‐3,4‐diphenyl‐1,2‐thiazetidine 1,1‐dioxide 1 by reaction of its anion 4 with alkyl halides. cis‐ and trans‐Configuration of the 4‐alkylated products were determined by 1H‐nmr and NOE difference spectro‐scopy studies.
Synthesis and derivatization of novel 4‐aroylthiophene‐and furan‐2‐sulfonamides
Authors: Hartman George D. , Halczenko Wasyl 
Published: March 2009

AbstractSulfonation of 3‐aroylthiophenes and furans with sulfuric acid in acetic anhydride regioselectively affords the corresponding 2,4‐disubstituted heterocycle. Benzylamine derivatives of the parent sulfonamides are obtained either by Mannich reaction of aryl phenols, orviaa sequence employing free radical bromination followed by selective ammonolysis. This methodology provides ready access to a wide variety of regioselectively‐substituted heterocycles.
Studies in spiroheterocycles. Part XIII. Synthesis of a novel spiro system: Spiro[9H‐acridine‐9,3′‐[3h]indol]‐2′(1′H)‐one and related compounds from new fluorinated spiro[3H‐indole‐3,9′‐[9H]xanthen]‐2(1H)‐ones
Authors: Joshi Krishna C. , Jain Renuka , Dandia Anshu , Garg Saroj , Ahmed Nidhal 
Published: March 2009

AbstractA new spiroheterocyclic system spiro[9H‐acridine‐9,3′‐[3H]indol]‐2′(1′H)‐one and related compounds have been prepared by the reaction of spiro[3H‐indole‐3,9′‐[9H]xanthen]‐2(1H)‐ones with aromatic amine or ammonium acetate. The latter were prepared by heating fluorinated indole‐2,3‐diones with m‐/p‐cresols or α‐naphthol in the presence of sulphuric acid at 230‐240°. The synthesized compounds have been characterized on the basis of their elemental analyses, ir, nmr (1H, 13C, 19F) and mass spectral data.
Ring closure reactions of methyl N‐(haloacetyl)anthranilates with ammonia
Authors: Cho Nam Sook , Song Ki Youn , Párkányi Cyril 
Published: March 2009

AbstractIn the presence of ammonia, methyl N‐(bromoacetyl)anthranilate (4) is cyclized into 3H‐1,4‐benzodiaze‐pine‐2,5(1H,4H)‐dione (1). However, when 4 is replaced with methyl N‐(chloroacetyl)anthranilate (6), the only heterocyclic product formed in the reaction is 2‐(chloromethyl)quinazoline‐4(3H)‐one (7). Under analogous conditions, 3‐haloacetamidocrotonates (9, 10) do not yield any heterocyclic products and no 1,4‐diazepines can be obtained.
Synthetic approaches to hexahydropyrrolo[1,2‐b]isoquinolones
Authors: Smith Forrest T. , Deruiter Jack , Carter Deborah Ann 
Published: March 2009

AbstractSynthetic routes to 1,2,3,5,10,10a‐hexahydropyrrolo[1,2,‐b]isoquinolin‐5‐ones functionalized at C‐10 were investigated. Attempts to prepare the ketone 2, and subsequently introduce the desired C‐10 hydroxymethylene group were unsuccessful due to the failure of 6 to cyclize and the unreactivity of 9 to relevant nucleophiles. Compound 1 was prepared by the condensation of 1‐pyrroline with 7‐methoxyisobenzopyran‐1,3,‐(4H)‐dione to give 12 in quantitative yield. Acyl halide formation and subsequent reduction gave the desired compound 1.
Synthesis of 6‐amino and 6‐ethoxy‐2(1H)‐pyridone derivatives
Authors: Cocco Maria Teresa , Congiu Cenzo , Maccioni Antonio , Plumitallo Antonio 
Published: March 2009

AbstractAn efficient route allowing the synthesis of 6‐amino and 6‐ethoxy‐2(1H)‐pyridone derivatives by reaction of ethyl cyanoacetimidate, ethyl ethoxycarbonylacetimidate and related acetamidines with diethyl ethoxymeth‐ylenemalonate (EMME) is reported. The formation of dienamino derivatives as intermediates and their heterocyclization to the 2(1H)‐pyridone derivatives is described.
A novel synthesis of 2‐vinylindoles and their utilization in the diels‐alder reaction for the formation of new [c] annellated carbazole derivatives
Authors: Akgün Eyup , Tunali Mustafa , Erdönmez Giray 
Published: March 2009

AbstractA facile synthesis of 2‐vinylindoles is detailed, starting from the corresponding indolecarbinols. The utility of the newly synthesized 2‐vinylindoles in the preparation of novel [c] annellated carbazoles is demonstrated. 1‐(1‐Methyl‐2‐indolyl)‐1‐(N‐methyl‐2′‐pyrrolyl)ethene (3c) has also a 2‐vinylpyrrole partial structure. However, in the Diels‐Alder reaction of 3c, the exclusive formation of [c] annellated indoles was observed.
Epoxidation of 2‐azabicyclo[2.2.1]hept‐5‐en‐3‐one
Authors: Legraverend Michel , Bisagni Emile , Huel Christiane 
Published: March 2009

AbstractEpoxidation of 2‐azabicyclo[2.2.1]hept‐5‐en‐3‐one has been performed in high yield with potassium hydrogen persulfate at pH 6, 1H nmr data indicate an exo stereoconfiguration of the epoxide.
A New synthesis of 4,5,6,7‐tetrahydrofuro[2,3‐c]pyridines and furo[2,3‐c]pyrrolidines
Authors: Arnoldi Anna , Bregante Giovanna , Caldirola Patrizia , Merlini Lucio , Tamburini Bruno 
Published: March 2009

AbstractNew syntheses of 4,5,6,7‐tetrahydrofuro[2,3‐c]pyridines and furo[2,3‐c]pyrrolidine derivatives, starting from furan‐3‐carboxaldehyde, are reported.
The acid‐catalyzed rearrangement of 1‐N‐allylindolines
Authors: Izumi Taeko , Kasahara Akira 
Published: March 2009

AbstractZinc chloride‐catalyzed rearrangement of 1‐N‐allylindoline and 1‐N‐(2‐methylallyl)indoline proceeds readily in refluxing xylene to give 7‐allylindoline and 7‐(2‐methylallyl)indoline in 73% and 86% yields, respectively. The reaction of 1‐N‐2‐butenylindoline and zinc chloride give rise to the mixture of 7‐(1‐methylallyl)indoline, 7‐(cis‐ and trans‐1‐methyl‐1‐propenyl)indoline, and 7‐(trans‐2‐butenyl)indoline. On the other hand, the similar reaction of 1‐N‐(3‐methyl‐2‐butenyl)indoline with zinc chloride led to the formation of a mixture of 1,2,5,6‐tetrahydro‐4,4‐dimethyl‐4H‐pyrrolo[3,2,1‐ij]quinoline and 7‐(3‐methyl‐2‐butenyl)indoline.
Synthesis of benzimidazo‐substituted 3‐quinolinecarboxylic acids as antibacterial agents
Authors: Bran̂a Miguel F. , Castellano José M. , Yunta María J. R. 
Published: March 2009

AbstractThe 6‐ and 7‐(1‐ethylbenzimidazolyl)‐substituted 1‐ethyl‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acids were synthesized. Antibacterial activity was tested in vitro. Only one of the new compounds prepared showed slight antibacterial activity against one of the strains tested. So, they are of no interest as antibacterial agents.
Synthesis of isochroman‐fused pyrazolone and pyrimidine derivatives
Authors: Wang Jin‐Jun , Yin Bing‐Zhu , Jiang Gui‐Ji , Imafuku Kimiaki 
Published: March 2009

AbstractUnsubstituted 5, and 2‐aryl‐ 6a‐c, or 2‐(2‐benzothiazolyl)‐substituted 1,3‐dihydroisochromano[4,3‐c]pyrazol‐3(2H)‐ones 7a‐f were prepared by the reactions of 3‐ethoxyoxalyl‐ 2, or 3‐ethoxycarbonylisochroman‐4‐one 3 with hydrazine derivatives. The reactions with amidines gave 2‐substituted 4‐hydroxyisochromano[4,3‐d]‐pyrimidines 8a‐c.
Arene imine derivatives of nitrogen heterocycles: 1a,9b‐dihydrobenz[h]‐azirino[f]quinoline, 1a,9b‐dihydrobenz[f]azirino[h]quinoline and 1a,9b‐dihydroazirino[f][1,10]phenanthroline
Authors: Abu‐Shqara Elias , Blum Jochanan 
Published: March 2009

AbstractThe syntheses of the K‐imine derivatives of benzo[h]quinoline (1), benzo[f]quinoline (2) and 1,10‐phenanthroline (3) are described. The parent nitrogen heterocycles were oxidized with sodium hypochlorite to the corresponding K‐oxides, 4, 6 and 8, which in turn were reacted with sodium azide. The resulting azido alcohols were then cyclized with triethyl phosphite to the title compounds 5, 7 and 9. The oxirane ring cleavage in benzo[h]quinoline 5,6‐oxide (4) and in benzo[f]quinoline 5,6‐oxide (6) by sodium azide proceeded by the predicted regioselectivity: 4 gave trans‐5‐azido‐5,6‐dihydro‐6‐benzo[h]quinolinol (11) and trans‐6‐azido‐5,6‐dihydro‐5‐benzo[h]quinolinol (10) as the major and minor products respectively, and 6 yielded solely trans‐6‐azido‐5,6‐dihydro‐5‐benzo[f]quinolinol (12). The latter compound proved by X‐ray analysis to crystallize as a hydrogen bonded dimer.
Reaction of biguanides and related compounds. XVI. Synthesis of s‐triazinones and fused s‐triazinones by carbonylation of biguanides and related compounds with diethyl azodicarboxylate
Authors: Kihara Yoshito , Kabashima Shigeru , Yamasaki Tetsuo , Ohkawara Tadashi , Furukawa Mitsuru 
Published: March 2009

AbstractBiguanides and the related compounds, in which a moiety of biguanide is involved in the structure as a part of the ring, were allowed to react with diethyl azodicarboxylate to afford triazinones and fused heterocycles including a triazinone ring, respectively. The mechanism of the reaction was elucidated to proceed through the initial formation of the amide intermediate, followed by cyclization to triazinone ring systems with elimination of nitrogen.
Synthesis of some novel polyoxygenated quinolines
Authors: Jaroszewski Jerzy W. 
Published: March 2009

AbstractPolyfunctional quinolines were obtained via thermal cyclization of phenylaminocrotonates and malonanilides and characterized by uv, ir, and 1H and 13C nmr spectra. Dehydration of a derivative of 5‐hydroxymethyl‐4(1H)‐quinolone yielded a derivative of 5H‐furo[2,3,4‐de]quinoline, representing a novel tricyclic system.
Reaction of β‐arylidennaphthylamines with 4‐hydroxycoumarin. A correction in structural assignment of the product. III
Authors: Martínez Roberto , Cortés Eduardo , Toscano Rubén A. , Alfaro L. Josué 
Published: March 2009

AbstractThe reaction of 4‐hydroxycoumarin with β‐arylidennaphthylamines constitutes a convenient synthetic route to the hitherto unknown 2H‐benzo[f][1]benzopyrano[4,3‐b]quinolin‐2‐one, VI. The X‐ray crystallography data conform with the present benzopyrano[4,3‐b]quinolin‐2‐one ring system and disprove the benzopyrano[3,4‐c]quinolin‐2‐one structure previously assigned for such reaction products.
A convenient synthesis of 3‐aryl‐3,4‐dihydroisoquinolinium salts
Authors: Badía D. , Carrillo L. , Domínguez E. , Cameno A. G. , Martínez De Marigorta E. , Vicente T. 
Published: March 2009

AbstractA convenient synthesis of the title compounds proceeding via direct Bischler‐Napieralski cyclization reaction of the appropriate N,N‐dialkylformamides obtained from the adequate imines is described. The reported procedure implies synthetically useful yields and mild reaction conditions.
A series of novel acyclic nucleosides. II. Synthesis of acyclic nucleosides bearing an imidazo[4,5‐d] [1,3]oxazine ring
Authors: Matsumoto Hiroatsu , Kaneko Chisato , Mori Takeo , Mizuno Yoshihisa 
Published: March 2009

AbstractNovel acyclic nucleosides 3a,b,c where N‐1 of acyclovir is replaced by oxygen atom were prepared. Thus, 1‐[(2‐acetoxyethoxy)methyl]‐5‐amino‐4‐ethoxycarbonylimidazole (9) was treated with ethoxycarbonyl isothiocyanate or benzoyl isothiocyanate to give 11e,f. Methylation of the latter with methyl iodide afforded S‐methylisothiourea derivative 12f which was treated with alkali and subsequently the mixture was neutralized to give 5‐amino‐3‐[(2‐hydroxyethoxy)methyl]‐3H‐imidazo[4,5‐d][1,3]oxazin‐7‐one (3a). Compounds 3b,c were obtained by treatment of acetic anhydride or propionic anhydride with sodium 5‐amino‐1‐[(2‐hydroxyethoxy)methyl]imidazole‐4‐carboxylate (7) which was prepared via 5‐amino‐[(2‐acetoxyethoxy)methyl]‐imidazole‐4‐carboxamide (5). Evaluation of acyclic oxanosine analogs for cytotoxicity and activity against herpes simplex virus type 1 (HSV‐1) revealed that all the derivatives tested were inactive, but cytotoxicity were similar or less as compared to that of acyclovir.
Diheterocyclic compounds from dithiocarbamates and derivatives thereof. III. 3,3′‐arylenebis(2,4‐dioxo‐1,2,3,4‐tetrahydroquinazolines)
Authors: Garín Javier , Meléndez Enrique , Merchán Francisco L. , Merino Pedro , Orduna Jesús , Tejero Tomás 
Published: March 2009

AbstractThe title compounds 3 were synthesized from dimethyl N,N′‐arylenebisdithiocarbamates 1. An alternative synthesis for 3 and their 3,3′‐(6,6′‐dibenzothiazole‐2,2′‐diyl) analogues 7 is also described.
Synthesis, structural and conformational study of 6‐hydroxy (or acyloxy) derivatives of the 1,3‐dimethyl‐1,3‐diazoniatricyclo[3.3.1.13–7]decane system
Authors: Fernández M. J. , Gálvez E. , Lorente A. , Camuñas J. A. , Sanz J. , Fonseca I. 
Published: March 2009

Abstract1,3‐Dimethyl‐1,3‐diazoniatricyclo[3.3.1.13–7]decan‐6‐ol, and his p‐chlorobenzoxy and diphenylacetoxy derivatives have been synthesized and studied by 1H and 13C nmr spectroscopy. The crystal structure of the alcohol 2a has been determined by X‐ray diffraction. Each ring of the adamantane cage system is a nearly perfect chair. From the 1H and 13C nmr data, several stereoelectronic effects have been deduced.
Metallation of diazines II. First metallation of pyridazine, metallation of 2,4‐dichloropyrimidine
Authors: Turck A. , Plé N. , Mojovic L. , Quéguiner G. 
Published: March 2009

Abstract3,6‐Dichloropyridazine was ortho‐lithiated by lithium 2,2,6,6‐tetramethylpiperidide. The resulting lithio compound was reacted with carbonyl derivatives iodine and trimethylchlorosilane. An azaxanthone was synthesised. An unusual regioselectivity for the lithiation of 2,4‐dichloropyrimidine was studied.
New dehydration in the pyrrolo[1,2–6‐b]isoquinoline series. Preparation and structural identification of 3,5‐dihydrobenz[f]indolizin‐3‐one
Authors: Rigo Benoít , Tullier Etienne , Barbry Didier , Couturier Daniel , Warin Vincent , Lamiot Jocelyne , Baert François 
Published: March 2009

Abstract3,5‐Dihydrobenz[f]indolizin‐3‐one was prepared by a novel dehydration reaction involving the heating of 1,2,3,5,10,10a‐hexahydro[f]indolizine‐3,10‐dione with polyphosphoric acid. The structure of this new compound was established by X‐ray crystallography, by nmr spectroscopy and by reduction to the known products 1,2,3,5‐tetrahydrobenz[f]indolizin‐3‐one and 1,2,3,5,10,10a‐hexahydrobenz[f]indolizin‐3‐one.
Stereoselective synthesis and stereochemical determination of 2,5‐dialkylpyrrolidines and 2,6‐dialkylpiperidines
Authors: Bacos D. , Célérier J. P. , Marx E. , Rosset S. , Lhommet G. 
Published: March 2009

Abstractω‐Alkyllactams 3 can be transformed into ω‐alkyl cyclic β‐enaminoesters 7 which are good precursors of insects venom alkaloids. A stereoselective synthesis of dialkylpyrrolidines and Solenopsine A is described followed by an easy stereochemical determination by 13C nmr.
Synthesis of 2‐chloro‐4,6‐di(heteroaryl)pyrimidines
Authors: Strekowski Lucjan , Harden Donald B. , Grubb William B. , Patterson Steven E. , Czarny Agnieszka , Mokrosz Maria J. , Cegla Marek T. , Wydra Roman L. 
Published: March 2009

AbstractA practical method for the preparation of 2‐chloro‐4,6‐di(heteroaryl)pyrimidines and their 5‐methyl homologues from readily available 2‐chloropyrimidine and 2‐chloro‐5‐methylpyrimidine, respectively, is described. The method is based on the addition reactions of heteroaryllithium reagents with chloropyrimidines followed by dehydrogenation of the resultant substituted dihydropyrimidines. The use of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone as the dehydrogenation agent gives the best results. Side reactions in the addition step are discussed.
Studies on quinazolinones. 2. Synthesis of 2‐(4‐benzylpiperazin‐1‐ylmethyl)‐2,3‐dihydro‐5H‐oxazolo[2,3–6]quinazolin‐5‐one and ‐2,3‐dihydro‐5H‐thiazolo[2,3‐b]quinazolin‐5‐one
Authors: Shiau Chia‐Yang , Chern Ji‐Wang , Liu Kang‐Chien , Chan Chao‐Han , Yen Mou‐Hsiung , Cheng Ming‐Chu , Wang Yu 
Published: March 2009

AbstractTo search for novel antihypertensive heterocycles in the condensed quinazoline series, two representative compounds were synthesized via a suitable reaction sequences. Treating anthranilonitrile with allyl isocyanate gave 2‐(allylureido)benzonitrile (10) in a quantitative yield. Compound 10 was cyclized to 3‐allylquinazoline‐2(1H, 4(3H)‐dione (11). Bromination of 11 in carbon tetrachloride converted it into the corresponding 3‐(2,3‐dibromopropyl) derivative (12) in 92% yield. Ring closure of 12 was effected by the action of alkali to afford 2‐bromomethyl‐2,3‐dihydro‐5H‐oxazolo[2,3‐b]quinazolin‐5‐one (13). The title compound, 2‐(4‐benzylpiperazin‐1‐ylmethyl)‐2,3‐dihydro‐5H‐oxazolo[2,3‐b]quinazolin‐5‐one (7) could be obtained by a reaction of either 12 or 13 with 1‐benzylpiperazine respectively. Starting from the readily available 3‐allyl‐2H‐thioxoquinazolin‐4(3H)‐one (16) via the analogous reactions gave the 2‐bromomethyl‐2,3‐dihydro‐5H‐thiazolo[2,3‐b]‐quinazolin‐5‐one (19) in good yield. However, the reaction of 19 with 1‐benzylpiperazine provided another target compound, 2‐(4‐benzylpiperazin‐1‐ylmethyl)‐2,3‐dihydro‐5H‐thiazolo[2,3‐b]quinazolin‐5‐one (8) only in poor yield (8%). As major product, the dehydrobrominated compound, 2‐methylene‐2,3‐dihydro‐5H‐thiazolo[2,3‐b]quinazolin‐5‐one (22) was isolated. A preliminary pharmacological evaluation revealed that both compounds 7 and 8 are devoid of the antihypertensive activity.
Proton‐ionizable crown compounds. 19. The synthesis of chiral dialkyl‐substituted triazolo‐18‐crown‐6 macrocycles
Authors: Bradshaw Jerald S. , Mcdaniel Christopher W. , Krakowiak Krzysztof E. , Izatt Reed M. 
Published: March 2009

AbstractFour new chiral macrocyclic polyether ligands containing the proton‐ionizable triazole subcyclic unit have been prepared. The triazolo‐crowns contain two isopropyl, two isobutyl, two (S)‐sec‐butyl or two benzyl substituents on chiral macro ring carbon atoms. A racemic triazolo‐18‐crown‐6 containing two (1‐naphthoxy)methyl substituents was also prepared.
A synthetic entry to isoxazolo[5,4‐d]pyrimidine‐4(5H)thione and isothiazolo[4,3‐d]isoxazole
Authors: Vicentini C. B. , Veronese A. C. , Poli T. , Guarneri M. , Giori P. , Ferretti V. 
Published: March 2009

Abstract4‐Thiocarbamoyl‐5‐aminoisoxazole 4 was used as a convenient starting material for preparing both isoxazolo[5,4‐d]pyrimidine‐4(5H)thiones 5 and 4‐aminoisothiazolo[4,3‐d]isoxazole 6. The structure of the latter compound was definitively assigned by X‐ray analysis.