bluuebunny/crossref_metadata_2025_split huggingface dataset:
New anti‐tumor agents. 2. Benzopyranylamine compounds
Authors: Jurd Leonard 
Published: March 2009

AbstractPyrrolidine, morpholine and piperidine derived Mannich bases of types 1–3 react with acetone, propionaldehyde and butyraldehyde to form 2‐methyl and 3‐methylbenzopyrans of types 4–8. Hydrolysis of these benzopyrans yields alcoholic benzopyrans which readily condense with a variety of amine, aniline and hydrazine derivatives to form diverse isomeric benzopyrans of types of 9 and 10. The benzopyrans 4–9 which contain a 3,4,5‐trimethoxyphenyl ring are active anti‐tumor agents, particularly against human breast, CNS and colon cancer cell lines, total growth inhibition of these tumors often occurring in vitro at concentrations as low as 10−5‐10−6 moles/1. Because of their in vitro activities and unusual structures a number of these benzopyrans have been selected for in vivo Xenograft testing against breast and other susceptible human cancers.
Syntheses of 1,2,4‐oxadiazole substituted pyrazole, isoxazole and pyrimidine heterocycles
Authors: Neidlein Richard , Li Sheng 
Published: March 2009

AbstractSyntheses of two series of heterocyclic compounds having 1,2,4‐oxadiazole‐, together with pyrazole‐, isoxazole‐ or pyrimidine‐rings which have similar structures are reported. The mechanisms of the reactions are discussed.
Studies on pyrrolidones. Reactivity of β‐enaminoesters derived from pyroglutamic acid. Synthesis of methyl cyano[l‐methyl‐5‐(5‐methyl[1,3,4]oxadiazol‐2‐yl)pyrrolidin‐2‐ylidene]acetate
Authors: Fasseur Dominique , Cauliez Pascal , Couturier Daniel , Rigo Benoît , Defretin Sébastien 
Published: March 2009

AbstractThe 5‐methoxycarbonyl group of β‐enaminoesters derived from methyl pyroglutamate was transformed into acids, amides and 1,3,4‐oxadiazole.
The difference between the reactivities of azomethine bonds in metamitron in electrochemical and chemical reductions
Authors: Riedl František , Ludvík Jiří , Liška František , Zuman Petr 
Published: March 2009

AbstractElectrochemical reduction of a herbicide metamitron (4‐amino‐3‐mefhyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one) in buffered aqueous solutions occurs on the protonated 1,6‐carbon‐nitrogen double bond. The 2,3‐double bond in the resulting 1,6‐dihydrometamitron is electrochemically reduced at considerably more negative potentials. In reaction with borohydride the 2,3‐double bond is reduced first. Reduction of the 1,6‐double bond is very little influenced by replacing the 2,3‐double bond by the ‐NHCH‐ grouping in 2,3‐dihydrometamitron.
Synthesis and central nervous system stimulant activity of camphor‐1,2,4‐benzotriazines fused with five and six‐membered heterocycles
Authors: Nagai Shin‐Ichi , Ueda Taisei , Takamura Masatoshi , Nagatsu Akito , Murakami Nobutoshi , Sakakibara Jinsaku 
Published: March 2009

AbstractNovel camphor‐1,2,4‐triazines fused with imidazole 2–3, thiadiazole 4, 1,2,4‐triazole 7, pyrimidine 9–13 and 1,3,5‐triazine 14, were synthesized starting from (5R,8S)‐3‐amino‐5,9,9‐trimethyl‐5,6,7,8‐tetrahydro‐5,8‐methano‐1,2,4‐benzotriazine 1. Evaluation of central nervous system stimulant activity demonstrated that the presence of a N‐N group at C‐3 position of 1,2,4‐benzotriazine will be essential for the activity.
Synthesis of several deoxy analogues of pancratistatin
Authors: Balázs LÁSzlÓ , Kádas István , Tõke László 
Published: March 2009

AbstractN‐Acetylated 1,4,7‐ and 3,4,7‐trideoxypancratistatin analogues 10 and 13 were synthesised from partially saturated phenanthridinones, 6 and 7, respectively via epoxidation and trans opening of the epoxides. Compounds 16 and 17, cis analogues of 13 were also synthesised from 7 via cis dihydroxylation with catalytic osmium tetroxide and N‐methylmorpholine N‐oxide. The stereoisomers obtained were separated by column chromatography after protection of the hydroxyl groups. The products synthesised are characterised satisfactorily by ir, nmr, ms and microanalysis data and are expected to possess anticancer or antiviral activity.
Synthesis of pyrido[2,3‐d]pyrimidines from aminopyrimidinecarbaldehydes
Authors: Perandones Francisco , Soto José L. 
Published: March 2009

Abstract2‐Methoxy‐4‐amino‐5‐pyrimidinecarbaldehyde (2a) as well as its 6‐methyl 2b and 6‐phenyl derivatives 2c were prepared by reduction of the corresponding aminopyrimidinecarbonitriles 1. Catalytic hydrogenation of 1a, 1b gives 5‐hydroxymethylpyrimidines 3a, 3b; under the same conditions 1c afforded 5‐aminomethylpyrimidine 4. Condensation of 2 with carbonitriles, ketones and polyfunctional carbonyl compounds bearing the ‐CH2CO‐ moiety afforded the pyrido[2,3‐d]pyrimidines and pyrimido‐[4,5‐b]quinoline derivatives.
A novel synthesis of 14‐(hydroxymethylalkyl) derivatives of dibenzoxanthenes and 3,3‐dimethyl‐4‐(2‐hydroxy‐1‐naphthyl)benzo[f]chroman
Authors: Sirkecioǧlu Okan , Talinli Naciye , Akar Ahmet 
Published: March 2009

AbstractSeveral reactions of 2‐naphthol with 2‐alkyl‐2‐hydroxymethylaldehydes have been investigated. Novel synthesis of 14‐(hydroxymethyl)alkyldibenzo[a,j]xanthenes and 3,3‐dimethyl‐4‐(2‐hydroxy‐1‐naphthyl)benzo[f]chroman has been realized.
The birch reduction of heterocyclic compounds. III. Birch reduction‐elimination reaction of 2‐ and 3‐furancarboxylic acid derivatives
Authors: Ohta Yasuo , Onoshima Man , Tamura Masumi , Tanaka Rika , Morimoto Yoshiki , Kinoshita Takamasa , Yoshihara Kazuo 
Published: March 2009

AbstractThe Birch reduction of 2‐(1‐alkoxyalkyl)furan‐3‐carboxylic acids 1a‐f gave 2‐alkyl‐3‐furancarboxylic acids 2a‐f with loss of the alkoxyl group in excellent isolated yields.
Fused imidazoacridines: Synthesis of 1,3‐dihydroimidazo[4,5‐b]‐acridin‐2‐one and 1,3‐dihydroimidazo[4,5‐a]acridin‐2‐one
Authors: Morel S. , Boyer G. , Galy J.‐P. 
Published: March 2009

AbstractThe synthesis of new 1,3‐dihydroimidazo[4,5‐a]acridin‐2‐one and 1,3‐dihydroimidazo[4,5‐b]acridin‐2‐one derivatives is reported. The yield and the structure of each isomer were determined by nmr spectroscopy.
Synthesis of novel pyrrolidin‐2‐ones: γ‐aminobutyric acid cyclic analogues
Authors: Ebrik S. Al Akoum , Rigo B. , Vaccher C. , Vaccher M‐P. , Flouquet N. , Debaert M. , Berthelot P. 
Published: March 2009

AbstractSome new N‐substituted pyrrolidin‐2‐ones, cyclic analogues of baclofen and of 3‐(5‐methoxybenzo‐[b]furan‐2‐yl)‐γ‐aminobutyric acid, have been prepared and characterized, starting from 4‐(4‐chlorophenyl)‐pyrrolidin‐2‐one and 4‐(5‐methoxybenzo[b]furan‐2‐yl)pyrrolidin‐2‐one.
Synthesis of novel pyridazino[4,5‐b][1,4]oxazine‐3,5‐diones
Authors: Cho Su‐Dong , Kweon Deok‐Heon , Kang Young‐Jin , Chung Hyun‐A , Yoon Yong‐Jin 
Published: March 2009

AbstractNovel pyridazino[4,5‐b][1,4]oxazine‐3,5‐diones were synthesized from N‐[2‐(3,4‐dimethoxyphenyl)‐ethyl]‐2‐chloroacetamide (or 2‐chloropropanamide) and 1‐alkyl‐5‐halo‐4‐hydroxypyridazin‐6‐ones in good yield.
Isoquinolinium N‐arylimides and strained cycloalkenes
Authors: Temme Robert , Huisgen Rolf 
Published: March 2009

AbstractIn contrast to common alkenes and enol ethers, the angle‐strained double bonds of norbornene, dimethyl norbornadiene‐2,3‐dicarboxylate, and acenaphthylene undergo [3+2] cycloadditions with isoquinolinium N‐arylimides. The structures of the crystalline adducts have been elucidated from their 1H nmr spectra.
Synthesis and properties of cyclohepta[cd]benzothiophenes
Authors: Horaguchi Takaaki , Kubo Takuji , Tanemura Kiyoshi , Suzuki Tsuneo 
Published: March 2009

AbstractCyclohepta[cd]benzothiophene 3, a new heterocyle, was synthesized starting from benzothiophene via eight steps in 14% total yield. Chemical reactions of 3 were examined on formylation, acetylation, bromination, catalytic hydrogenation and Diels‐Alder reactions. The results show that the benzothiophene moiety of 3 has aromatic character and the carboncarbon double bonds in a seven‐membered ring posseses alkene‐1ike character.
Simple synthetic route to polyhydroxylated pyrrolidines and piperidines
Authors: Lee Sang Gyeong , Yoon Yong‐Jin , Park Ki Hun 
Published: March 2009

AbstractA short and simple synthetic route to polyhydroxylated piperidines and pyrrolidines were described with D‐glucurono‐δ‐lactone as chiral educt. Key reaction steps included selective cleavage of terminal isopropylidene group of compound 12 with Dowex 50W‐X8 resin (H+ form), regioselective ring opening of epoxide 16 and intramolecular nucleophilic amination of compound 14 and 18.
Towards lipophilic derivatives of S‐adenosyl‐L‐methionine
Authors: Juanes Olga , Goya Pilar , Martinez Ana 
Published: March 2009

AbstractTwo different strategies for the synthesis of S‐Adenosyl‐L‐methionine liphophilic derivatives have been attempted. The first chemical direct modification performed on S‐adenosyl‐L‐methionine is described.
Steroidal isoxazoles, isoxazolines and isoxazolidines
Authors: Camoutsis Ch. , Nikolaropoulos S. 
Published: March 2009

AbstractThe present review considers new useful heterocyclosteroids which contain five‐membered heterocyclic systems, namely, isoxazoles, isoxazolines and isoxazolidines, condensed to the cyclopentanoperhy‐drophenanthrene skeleton, in different positions of the molecule, with changes in their physiological activity and the appearance of new interesting biological properties. Literature coverage for the review includes publications up to the end of 1996.
Ring transformations of heterocyclic compounds. XVI. Spiro[cyclohexadiene‐dihydroacridines]. A novel class of spirodihydroacridines by ring transformation of pyrylium salts with 9‐methylacridine and its quaternary salts
Authors: Zimmermann Thomas , Abram Ulrich , Schmidt Klaus 
Published: March 2009

Abstract2,4,6‐Triarylpyrylium salts 1 react with the in situ generated anhydrobase of 9,10‐dimethylacridinium methosulfate (2a) in the presence of anhydrous sodium acetate in ethanol by a 2,5‐[C4+C2] pyrylium ring transformation to give the hitherto unknown 6‐aroyl‐3,5‐diaryl‐10′‐methylspiro[cyclohexa‐2,4‐diene‐1,9′‐9′,10′‐dihydro‐acridines] 3. When the pyrylium perchlorate 1a is treated under the same conditions with the N‐ethyl, N‐allyl or N‐benzyl substituted acridinium salts 2b‐d a dealkylation of these salts occurs and the N‐unsubstituted spiro[cyclohexadiene‐dihydroacridine] 4a is formed. The same compounds 4 can also be obtained by transformation of the pyrylium salts 1 with 9‐methylacridine (7) and triefhylamine/acetic acid in ethanol. Structure elucidation is performed by an X‐ray crystal structure determination of the spiro[cyclohexadiene‐dihydroacridine] 3a. Spectroscopic data of the transformation products and their mode of formation are discussed.
Computational study of ethylene, acetylene, and cyclopropene addition to heterocycles with two heteroatoms in the 1,2 position
Authors: Jursic Branko S. 
Published: March 2009

AbstractThe AM1 semiempirical and B3LYP density functional theory computational studies are undertaken with the target being to explore cycloaddition reactions with heterocycles that have two heteroatoms in the ring's 1 and 2 positions as an initial synthetic step in the preparation of allene's acetylene derivatives. Several qualitative computational approaches were used to evaluate the heterocycle reactivity, including two new approaches using electronic and bond order changes in transformation of the reactant pair into corresponding transition state structures. Finally, the reactivity was evaluated by computing activation barriers, and the feasibility of the proposed synthetic transformations was discussed.
A facile synthesis of cyanophenothiazines
Authors: Marivingt‐Mounir Céacile , Mettey Yvette , Vierfond Jean‐Michel 
Published: March 2009

AbstractA one‐pot synthesis of 1, 3 and 4‐cyanophenothiazines and a two‐step approach to 2‐cyanoisomer have been developed. The condensation of 2‐aminobenzenethiol and 2,3 or 3,4‐dihalogenobenzonitriles followed by Smiles rearrangement or by intramolecular aromatic substitution gave the desired ring systmes.
Pyrolysis and photolysis of 1‐aroylamino‐4,5‐diaryl‐1,2,3‐triazoles: Generation and thermal transformations of 4,5‐diaryl‐1,2,3‐triazolyl radicals
Authors: Hadjiantoniou‐Maroulis C. P. , Charalambopoulos A. Ph. , Maroulis A. J. 
Published: March 2009

AbstractThe pyrolysis of 1‐aroylamino‐4,5‐diphenyl‐1,2,3‐triazoles 1 yields, pressumably via the 4,5‐diphenyl‐1,2,3‐triazolyl radical (2a), 2,3‐diphenyl‐2H‐azirine (11a) and 2‐aryl‐4,5‐diphenylimidazoles 14 as the major products. Upon irradiation 1‐benzoylamino‐4,5‐diphenyl‐1,2,3‐triazole (1a) gives 4,5‐diphenyl‐1 (2)H‐1,2,3‐triazole (4a) via the 1,2,3‐triazolyl radical 2a, together with benzamide (5a) and 1,2‐bisbenzoylhydrazine (6a). Products 5a and 6a result from the benzoylamino radical 3a by hydrogen atom abstraction and dimerization respectively.
Synthesis of hydroxy‐substituted aza‐analogues of antitumor anthrapyrazoles
Authors: Krapcho A. Paul , Gallagher Cynthia E. , Hammach Abdelhakim , Hacker Miles P. , Menta Ernesto , Oliva Ambrogio , Di Domenico Roberto , Da Re Giovanni , Lotto Andrea , Spinelli Silvano 
Published: March 2009

AbstractSynthetic routes have been developed which lead to ring‐hydroxylated aza‐analogues of antitumor anthrapyrazoles, namely, 2,5‐bis[(aminoalkyI)amino] substituted 10‐hydroxymdazolo[3,4‐fg]isoquinolin‐6(2H)‐ones 1 and 7‐hydroxyindazolo[4,3‐gh]isoquinolin‐6(2H)‐ones 2. The regiospecific synthesis of 6,9‐dihalo‐4‐hydroxybenz[g]isoquinolines 3 and 4 has been accomplished. Intermediate 3 was constructed in a multistep process involving Diels‐Alder chemistry of benzoylacrylates whereas 4 was assembled using Ni(II) mediated coupling of methyl 3‐chloro‐5‐methoxyisonicotinate (15b) with the organic zinc reagent 18 derived from 2‐fluoro‐5‐chlorobenzyl bromide (17). After protection of the hydroxy group with a p‐methoxybenzyl moiety, the different nucleofugacities of the leaving groups present in 10 and 20 allowed sequential displacements by substituted hydrazines and amines, respectively, to lead to the desired p‐methoxybenzyl protected analogues 12 and 22. Deprotection led to the side arm modified compounds 1 and 2. The displacements of 21a and 21b with N,N‐dimethylethylenediamine also led to the tri[(aminoalkyl)amino]substituted analogues 23a and 23b, respectively, which arose from further SNAr substitutions of the p‐methoxybenzyloxy group.
Synthesis of a new decahydrohexapyrrin of biosynthetic interest
Authors: Kogan Marcelo J. 
Published: March 2009

AbstractA new decahydrohexapyrrin containing a tert‐butoxycarbonylbilane of type III was prepared applying a convergent type synthesis. The order of the side chains of the tert‐butoxycarbonylbilane belonging to this oligopyrrole corresponds to that of a type HI uroporphyrinogen. A symmetric hexapyrrol dilactam was formed as a by product of the synthesis.
Synthesis of thienoimidazothiazoles
Authors: Binder Dieter , Pyerin Michael , Schnait Heinz 
Published: March 2009

AbstractThree isomeric substituted thienoimidazothiazoles were synthesized as thiophene analogs of the immune modulator TILOMISOL, by cyclizing appropriate β‐oxothioethers of thienoimidazoles. In contrast to the benzene analog no intermediates were observed at this step.
Synthesis of novel heterocycles from 2‐amino‐3‐(cyanomethylsulfonyl)thiophene
Authors: Stephens Chad E. , Sowell J. Walter 
Published: March 2009

AbstractThe synthesis and selected reactions of 2‐amino‐3‐(cyanomethylsulfonyl)thiophene is reported. In particular, cyclization reaction of the versatile aminothiophene yielded a number of novel thieno[3,2‐b][1,4]‐thiazine 1,1‐dioxides, as well as the analogous thieno[2,3‐e][1,3,4]thiadiazine 4,4‐dioxide. Reaction of the thienothiazine system with hydrazine was subsequently explored, which resulted in either ring‐opening of the thiazine and formation of an aminopyrazole or solely ring cleavage depending on the thiazine substituent. Additionally, the synthesis of bis(2‐amino‐3‐thienyl)sulfone and the corresponding bis‐acetamide is described.
The synthesis of 3‐[(dimethylamino)(2‐phenyl‐5‐oxo‐2‐oxazolinyl‐idene‐4)methyl]imidazo[1,2‐x]azines and related compounds, intermediates in the formation of azaaplysinopsin derivatives
Authors: Bratušek Urška , Hvala Aleš , Stanovnik Branko 
Published: March 2009

Abstract4‐(2‐Bromo‐1‐dimethylaminoethylidene)‐2‐phenyl‐5(4H)‐oxazolone (5) reacts with N,N‐dimethyl‐N'‐heteroarylformamidines 7 to form imidazoazine derivatives 9 with the oxazolone ring connected through a conjugated double bond to the fused imidazole system at position 3. Compounds 9 were transformed with sodium methoxide in methanol into 2‐benzoylamino‐3‐dimethylamino‐3‐imidazoazinylpropenoates 10, while by treatment with hydrochloric acid in methanol, 3‐(benzoylaminoacetyl)imidazoazines 12 were formed. The synthesis of compounds 9 represents a facile route to intermediates in the synthesis of azaaplysinopsin and related systems.
Synthesis and application of ethyl 2‐arylazo‐4,9‐dioxonaphtho[2,3‐b]thiophene‐3‐carboxylate
Authors: Rangnekar D. W. , Kanetkar V. R. , Shankarling G. S. , Malanker J. V. 
Published: March 2009

AbstractSynthesis of ethyl 2‐arylazo‐4,9‐dioxonaphtho[2,3‐b]thiophene‐3‐carboxylate was achieved by diazotization of ethyl 2‐amino‐4,9‐dioxonaphtho[2,3‐b]thiophene‐3‐carboxylate and coupling with selected N,N‐dialkylanilines. The key intermediate ethyl 2‐amino‐4,9‐dioxonaphtho[2,3‐b]thiophene‐3‐carboxylate was synthesized by the condensation of sodium salt of ethyl cyanoacetate with 2,3‐dichloro‐1,4‐naphthoquinone. Ethyl 2‐arylazo‐4,9‐dioxonaphtho[2,3‐b]thiophene‐3‐carboxylate were applied on polyester fibers as disperse dyes and their dyeing properties were studied.
Knoevenagel reaction of malononitrile with methyl ketone followed by double cyclization catalyzed by potassium fluoride‐coated alumina
Authors: Nakano Yoshiharu , Shi Wei‐Ying , Nishii Yoshiyuki , Igarashi Minoru 
Published: March 2009

AbstractQualitative limitations were presented for a formation reaction of a series of bridged compounds from ketones and malononitrile catalyzed with potassium fluoride‐alumina in acetonitrile [1]. The bridged com pounds were obtained from only unhindered alkyl methyl ketones. The compounds released hydrocarbon to give pyridine derivatives.
Controlling substitution patterns on the 1,2,4‐triazolo[1,5‐α]‐pyrimidine ring. Selective removal of chlorine at the 7‐position
Authors: Monte William T. , Kleschick William A. , Bordner Jon 
Published: March 2009

AbstractA highly effective method for the selective removal of chlorine from the 7‐position of the 1,2,4‐triazolo[1,5‐α]pyrimidine ring in the presence of chlorine at the 5‐ or 6‐positions is reported. The method involves treatment of the appropriate substrate with zinc‐copper couple in the presence of acetic acid in methanol‐tetrahydrofuran. The method enables the construction of a variety of substitution patterns in key intermediates for the 1,2,4‐triazolo[1,5‐α]pyrimidine sulfonanilide herbicides.
Thermal and photochemical reaction of isoxazolone with indole‐2,3‐dione derivatives
Authors: Pardasani R. T. , Pardasani P. , Muktawat S. , Ghosh R. , Mukherjee T. 
Published: March 2009

AbstractThe reaction of indole‐2,3‐dione derivatives with five membered heterocycle, viz isoxazolone under ther mal as well as photochemical conditions is described. While under refluxing ethanol these conditions afforded 2,3‐dihydro‐3‐(5′‐oxo‐3′‐phenylisoxazolidyl)indol‐2‐one 3 and a spiro product 2′,3′‐dihydro‐3,7‐diphenylspiro[diisoxazolo[4,5‐e:4,5‐b]pyran‐8,3′‐indol]‐2′‐one 4, the uv light induced irradiation mainly produced 4,5‐dioxo‐3‐phenylisoxazolo[5,4‐b][1]benzazepine 5 and 3‐phenylisoxazolo[5,4‐b]quinoline‐4‐carboxylic acid 6. The products have been characterised on the basis of spectral data and elemental analyses.
Synthesis and mechanism of formation of novel 2,5‐dihydro‐2,5‐diimino‐3,4‐di[(N,N‐dimethylamino)methylideneamino]pyrroles and 5‐amino‐3,4‐di[(N,N‐dimethylamino)methylideneamino]‐2H‐2‐iminopyrroles
Authors: Alves M. José , Carvalho M. Alice , Fernanda M. , Proença J. R. P. , Booth Brian L. , Pritchard Robin G. 
Published: March 2009

AbstractFormation of 5‐amino‐3,4‐di[(N,N‐dimethylarnino)methylidenearnino]‐2H‐2‐iminopyrroles 3 from the reaction of (Z)‐N1‐(2‐amino‐1,2‐dicyanovinyl)‐N2‐substituted‐formamidines 1 with dimethylformamide diethyl acetal has been shown to occur by initial formation of (Z)‐N1‐{l,2‐dicyano‐2‐[N,N‐dimethylamino)methylideneamino]vinyl}formamidines 8 (isolated), followed by base catalysed cyclisation and imi dazole ring opening by dimethyl amine. The kinetic product of the ring opening reaction is the 2,5‐diimino2,5‐dihydropyrrole derivatives 11, which have been isolated and characterized spectroscopically and by a single crystal X‐ray analysis on the R = Ph derivative. In solution at room temperature the N‐aryl derivatives undergo a rapid Dimroth rearrangement to give the thermodynamic ally more stable isomer 3, but compound 11 (R = Me) is much more stable in solution.
Conformationally locked heterocycles. Structure of a doubly bridged pyrimido[1,2‐a]pyrimidine from the hantzsch synthesis with 4‐(2‐hydroxyphenyl)but‐3‐en‐2‐one
Authors: Světlík Jan , Liptaj Tibor , Tureček FrantiŠEk 
Published: March 2009

Abstract1D and 2D nmr spectroscopy was used to assign the structure to the minor product from cyclocondensation of 4‐(2‐hydroxyphenyl)but‐3‐en‐2‐one with cyanamide, which was identified as (6R*, 9R*, 15R*, 17R*)‐6,9‐dimethyl‐6,17:9,15‐dimemano‐6H,15H,17H‐[1,3,5]benzoxadiazocino[4,5‐d][1,3,5]benzoxadiazocine‐7(9H)‐carbonitrile, a doubly oxygen‐bridged pyrimido[1,2‐a]pyrimidine derivative. The observed stereose lectivity and reaction mechanisms are discussed with the help of molecular mechanics and semi‐empirical PM3 calculations.
The synthesis of methyl 2‐(benzyloxycarbonyl)amino‐3‐dimethylaminopropenoate. The synthesis of trisubstituted pyrroles, 3‐amino‐2H‐pyran‐2‐ones, fused 2H‐pyran‐2‐ones and 4H‐pyridin‐4‐ones
Authors: Toplak Renata , Svete Jurij , Stanovnik Branko , Grdadolnik Simona GoliČ 
Published: March 2009

AbstractMethyl 2‐(benzyloxycarbonyl)aimno‐3‐dimemylaminopropenoate (2) was prepared from methyl N‐(benzyloxycarbonyl)glycinate (1) and t‐butoxybis(dimethylamino)methane, and used as a reagent for preparation of substituted 3‐(benzyloxycarbonyl)amino‐4H‐quinolizin‐4‐ones 5 and 6, −2H‐pyran‐2‐ones 17–19, −2H‐1‐benzopyran‐2‐ones 28–31, and ‐naphthopyrans 32–35, −2H‐pyrano[3,2‐c]pyridine‐2,5‐dione 46, ‐pyrano‐[4,3‐b]pyran‐2,5‐dione 47, ‐pyrano[3,2‐c]benzopyran‐2,5‐dione 48, ‐pyrano[2,3‐c]pyrazol‐6‐ones 49 and 50, ‐pyrano[2,3‐d]pyrirnidin‐7‐ones 51 and 52 derivatives. In the reaction of 2 with 1,3‐diketones trisubsti tuted pyrroles 14–16 were formed. Selective removal of benzyloxycarbonyl group was achieved by cat alytic transfer hydrogenation with Pd/C in the presence of cyclohexene to afford free 3‐amino compounds 7, 8, 20, 36–38 and 53–57 in yields better than 80%.
Thermal rearrangement of 1,3‐thiazolidine sulfoxides: Thiolsulfinate and thioaldehyde intermediates
Authors: Hahn Hoh‐Gyu , Nam Kee Dal , Mah Heduck 
Published: March 2009

AbstractStereospecific ring opening of the sulfoxides cis‐13 and trans‐14 in refluxing toluene gave the corre sponding sulfenic acids 9, 10 intermediates respectively. The sulfenic acid 9 dimerized to the thiolsulfinate 17 by dual function of the sulfenic acid as S‐nucleophile/S‐electrophile with loss of water while the sulfenic acid 10 was unchanged. The stereospecific recyclization of 10 to the parent sulfoxide 14 increases the higher pi‐electron density of the double. The thermolysis of the thiolsulfinate 17 gave the transient sulfenic acid 9, which dimerized again to repeat the process and unisolable thioaldehyde 21. The thioaldehyde 21 was con verted to either pyrrole 15 by the action of a sulfinic acid 20 catalyst formed inevitably by hydrolysis of 17 under the reaction conditions, or thiazole 18 under neutral conditions. In these rearrangements, the amide carbonyl group facilitated the elimination of a neighboring hydrogen.
Rearrangement of 2‐amino‐4‐(trifluoromethyl)oxazoles to hydantoins
Authors: Lawson Jon P. , VanSant Karey A. 
Published: March 2009

AbstractReaction of 2‐amino‐4‐trifluoromethyloxazoles with excess bromine in acetic acid/sodium acetate gives 5‐acetoxyhydantoins. The 5‐bromooxazoles are intermediates in the reaction.