bluuebunny/crossref_metadata_2025_split huggingface dataset:
The 1H and 13C nmr spectra of the “onium” salts of dithiacyclophanes
Authors: Ricci Alfredo , Danieli Roberto , Boicelli Andrea , Ridd John H. 
Published: April 2009

AbstractThe 1H and 13C nmr spectra of three cyclic sulphonium salts ol dithiacyclophanes have been recorded and compared with those of the open‐chain analogue. The 1H spectra indicate that methylation of the dithiacyclophanes gives a mixture of eonformational isorners with slightly different chemical shifts for the benzylic protons. The 13C spectra indicate that the smaller rings adopt an unsymmetrical conformation with respect to the aromatic ring but that in the larger ring studied, the aromatic carbon atoms are magnetically equivalent. The relevance of these results to the reactivity of the aromatic ring is discussed.
2,1‐benzisothiazoles. X. Acylation of 2,1‐benzisothiazolin‐3‐one. A remarkable sulfur extrusion with ring expansion
Authors: Davis Michael , Pogany Stephen P. 
Published: April 2009

AbstractAcylation of 2,1‐benzisothiazolin‐3‐ones (1) in pyridine gives O‐acyl derivatives initially; these rapidly extrude sulfur and form substituted 3,1‐benzoxazinones (4).
Inverted reactivity of aryllithium derivatives V. On the syntheses of thiocyano‐, phenylsulfinyl‐, and phenoxy derivatives of thiophenes and furans
Authors: Gronowitz Salo , Holm Boris 
Published: April 2009

AbstractThe reaction of some diheterocyclic iodonium salts with a variety of nucleophiles has been studied. The reaction was of preparative use for the syntheses of thiocyano, phenylsulfinyl and phenoxy derivatives of thiophenes and furans.
Acetylenic ketones. Part IV. Reaction of p‐nitrobenzoylphenylacetylene with nucleophilic nitrogen compounds
Authors: El‐Rayyes N. R. , Al‐Hajjar F. H. 
Published: April 2009

Abstractp‐Nitrobenzoylphenylacetylene (I) reacted with acylhydrazines (IIa‐d) to give the corresponding hydrazones (VIa‐d), which when treated with acetic anhydride, gave the same substituted pyrazole (VII). Hydrolysis of the latter with methanolic potassium hydroxide gave the pyrazole derivative (IX).The reaction of I with ethyl and phenyl hydrazinecarboxylates (IIe,f) led to the formation of the hydrazones (VIe) and (VIf), respectively, whereas with methyl‐ and phenylhydrazines it produced the pyrazoles (X) and (XI), respectively. However, guanidine hydrochloride gave with acetylenic ketone (I), the pyrimidine (XV).
Recherches en série azabenzodiazépine VII. Synthése de pyrazolo[3,4‐b]diazépines‐1,4
Authors: Affane‐Nguema J.‐P. , Lavergne J.‐P. , Viallefont Ph. 
Published: April 2009

AbstractPar action de l'acétylacétate d'éthyle ou de l'acétylacétone, sur des diamino‐4,5 pyrazoles, les pyrazolo[3,4‐b]diazépines‐1,4 sont synthétisées, soit directement, soit aprés cyclisation d'inter‐médiaires crotoniques ou cétoniques. Le sens de cyclisation et les structures des cycles diazépines sont démontrés. IIs correspondent á l'attaque initiale du carbonyle cétonique sur la fonction amine en position 4.
The photochemical synthesis of novel heterocyclic compounds from s‐triazolo [4,3‐b] pyridazine, III
Authors: Bradshaw Jerald S. , Tueller John E. , Baxter Steven L. , Maas Garren E. , Carlock John T. 
Published: April 2009

Abstracts‐Triazolo[4,3‐b]pyridazine (I) reacted photochemieally with bieyélo[2.2.1] hepla‐2,5‐diene, 1,5‐cyclooctadiene, 1,3‐cyclooctadiene, methylene cyclohexane, diethyl cis‐1,2,3,6‐tetrahydro‐phthalate and ethyl 2‐cyclopentene‐1‐acetate to givt: the following products: the endo and exo isomers of 4a, 5, 8a, 9‐tetrahydro‐9‐rnethylene‐5,8‐rnethano‐8H‐s‐triuzolo[1, 5‐a]indole (II) and the endo and exo‐9‐cyanometliyl products (III and IV) from bicyclo[2.2.1] hepta‐2,5‐diene; 4a,5,‐9, 10, 10a, 11‐huxahydro‐11‐methylene‐6H‐cycloocta[4,5]pyrrolo[1,2‐b]‐s‐triazole (V) and the 11‐cyanomethyl product VI from 1,5‐cyclooctadiene: 4a,7,8,9,10,10a‐hexahydro‐11 ‐inethylene‐11H‐cycloocta[4,5]pyrrolo[1,2‐b]‐s‐triazole(VII),4a, 5, 7, 8, 10a, 11‐hexahydro‐11‐methylene‐6H‐cycloocta[4,5]pyrroIo[1,2‐b]‐s‐triazole (VIII) and their respective 9‐cyanomethyl products (X and 1X) from 1,3‐cyclooctadiene; 6′, 7′ ‐dihydro‐7′ ‐methylenespiro[cyclohexane‐1, 5′‐[5H] pyr‐rolo[1,2‐b]‐s‐triazole] (XI), 6′, 7′‐dihydro‐7′‐meth) lene. spiro cyclohexane‐1, 6′‐[5H]pyrrolo[1,2‐b]‐s‐triazole] (XII) and their respective 7 ‐eyanomethyl products (XIII and XIV) from melhylene cyclohexane; 6,7‐dicarbethoxy‐9‐cyanomelhyl‐4a, 5, 7, 8, 8a, 9‐hexahydro‐6H‐s‐triazolo[1,5‐a]indole (XV) from diethyl cis‐1, 2, 3, 6‐tetrahydrophlhalate: and 5‐earl)elhoxymethyl‐8‐eyanomethyl‐4a, 5, 6, 7, 7a, 8‐hexahydrocyclopenta[4,5]pyrrolo( 1, 2‐b]‐s‐triazole (XVI) from ethyl 2, 2‐cyclo‐pentene‐1‐acetate. Many other alkenes, particularly the phenyl ethylenes, did not react with compound 1. In general, more than one product was isolated for each reaction except in the case of the two ester alkenes where a single eyanomethyl product was observed.
Synthesis, photooxidation and Z ⇌ E photoisomerization of benzalpyrrolinones
Authors: Lightner D. A. , Park Y‐T. 
Published: April 2009

AbstractIn contrast to oxodipyrromethenes and bilirubin, benzalpyrrolinones (H, P‐OCH3, p‐Cl, p‐N(CH3)2 and o‐CH3) and α‐pyridalpyrrolinones appear not to undergo dye‐sensitized photo‐oxygenation. They do, however, undergo an unsensitized E ⇌ Z photoisomerization reminiscent of stilbene photoisomerization, and the photostationary state varies with substituent. Intramolecular H‐bonding is implicated in the α‐pyridalpyrrolinone isomerization. In each case, the Z isomers are the therrnodynamically more stable ones, but the corresponding E isomers have been isolated and characterized following photoirradialion.
Action de l'anhydride acétique sur les (aziridinyl‐1)‐2 tétra‐hydropyrannes et sur les dialkylamino‐2 tétrahydropyrannes: Influence des substituants de l'azote sur l'orientation de la réaction
Authors: Ricart Guy , Clacet Charles , Couturier Daniel 
Published: April 2009

AbstractLes (aziridinyl‐1)‐2 tétrahydropyrannes sont obtenus par réaction d'Hofmann entre les α‐chlorotétrahydropyrannes et les aziridines; l'anhydride acétique les transforme en N‐(tétra‐hydropyrannyl‐2) N‐(β‐acétoxyéthyl) acélamides: il y a ouverture de l'hétérocycle azoté. Les dialkylamino‐2 tétrahydropyrannes avec le měme anhydride, réagissent ditféremment selon la nature des substituants alkyles de Tatome d'azote: les dérivés N‐diméthylés subissent la coupure carbone alpha‐azote pour donner un mélange d'acétoxy‐2 tétrahydropyrannes et de dimćthylacétamide; les composés N‐diéthylé's et autres fournissent des produits poly condensés, ayant vraisemblablement pour origine un clivage de la liaison carbone alpha‐oxygéne, et les dialkylacétamides correspondants. Une frontiére trés nette existe done entre les α‐aminotetra‐hydropyrannes N‐dimćthylés et N‐dialkylés.
Intramolecular cyclizations leading to bridgehead bicyclics 2. 5,5‐dialkylhydantoin derivatives
Authors: Okada Katsuhide , Kelley James A. , Driscoll John. S. 
Published: April 2009

AbstractThe effect of substituenls in the 5‐position on the course of hydantoin intramolecular alkylation reactions was studied. Dialkyl and diaryl substituted intermediates resulted in the same type product, 2,3‐dihydro‐6,6‐disubstituted imidazo[2,1‐b]oxazole‐5(6H)ones, indicating alkylation on oxygen rather than nitrogen. The mass spectral and nmr characteristics of these bicyclic compounds are discussed.
Pyrimidines. XIII. Novel pyrimidine to pyrimidine transformation reactions
Authors: Hirota Kosaku , Watanabe Kyoichi A. , Fox Jack J. 
Published: April 2009

AbstractNovel pyrimidine to pyrimidine transformation reactions are described. 1,3‐Dimethyl‐(or diethyl)‐uracil(1) are converted into isocytosine, 2‐thiouracil or uracil derivatives by treatment with guanidine, thiourea or urea, respectively. The latter two cases require base catalysis. The effects of some substituents at C‐5 and C‐6 of 1,3‐dialkylated uracils (1a → 1e) on this transformation were examined and a plausible mechanism is offered for their reaction. The utility of this reaction is exemplified by the facile two‐step conversion of pseudouridine into the anlileukemic agent, pseudoisocytidine, in good overall yield.
Preparation of azapyrylocyanine dyes
Authors: Reynolds G. A. , Vanallan J. A. 
Published: April 2009

AbstractAzapyrylocyanine and thiopyrylocyanine dyes were prepared from a 4‐aminopyrylium or 4‐aminothiopyrylium perchlorate and a 4‐methoxypyrylium or thiopyrylium perchlorate in the presence of a tertiary amine. The Absorption spectra of these dyes was shifted 107–125 mm to shorter wavelength compared to the corresponding methine dyes.
Mass spectral fragmentation pattern of 2,2′‐bipyridyls. Part VIII. 2,2′‐Bipyridyl‐5‐carboxylic Acid and 2,2′‐bipyridyl‐5‐sulphonic acid
Authors: Keats N. G. , Summers L. A. 
Published: April 2009

AbstractThe mass spectra of 2,2′‐bipyridyl‐5‐carboxylic acid and 2,2′‐bipyridyl‐5‐sulphonic acid obtained by electron impact are described. The principal initial fragmentation routes from the molecular ion of the carboxylic acid involve loss of CO, CN˙, HCN, CO2, OH˙ and H2O. From the molecular ion of the sulphonic acid the principal fragmentations are accompanied by loss of HCN, O3, SO2 and SO3.
Addition von aldehyden an aktivierte doppelbindungen, XV . Synthese von γ‐diketonen mit heterocyclischen substituenten und deren umsetzung zu N‐methylpyrrolen und chinolizidin bzw. Indolizidin systemen
Authors: Stetter Hermann , Krasselt Joachim 
Published: April 2009

AbstractAliphatische, aromatische und heterocyclische Aldehyde können unter Cyanid‐ bzw. Thiazoliumsalz‐Katalyse erfolgreich an α,β‐ungesattigte Ketone addiert werden. Die erhaltenen γ‐Diketone lassen sich leicht zu Pyrrol‐, Chinolizidin‐ bzw. Indolizidin‐Systemen umsetzen.
Studies on the chemistry of 2,3,5,6‐Tetrahydro‐6‐phenylimidazo[2,1‐b]‐thiazole. I. The reaction of N‐Alkyl derivatives with nucleophiles
Authors: Bigg D. C. H. , Faull A. W. , Purvis S. R. 
Published: April 2009

Abstract7‐Alkyl‐2,3,5,6‐tetrahydro‐6‐pheriylimidazo[2,1‐b]thiazoliurn salts behave as arnbident electro‐philes, which give ring‐opened products on reaction with a variety of nucleophiles. The results are rationalised in terms of thermodynamic or kinetic control.
Streptonigrin and related compounds III. Synthesis and microbiological activity of destrioxyphenylstreptonigrin and analogues
Authors: Rao Koppaka V. 
Published: April 2009

AbstractSynthesis of three tricyclic analogues of streptonigrin, based on the 2‐(2′‐pyridyl)quinoline‐5,8‐dione system and with the characteristic substitution pattern of rings A and C of streptonigrin is described. The C‐ring precursor, in the form of a substituted 2‐acetylpyridine was condensed with either 3‐hydroxy‐5‐methoxy‐2‐nitrobenzaldehyde or 3‐hydroxy‐4‐methoxy‐2‐nitrobenzaldehyde, followed by reductive cyclization and oxidation to the corresponding quinones 12 and 29. The 7‐amino substitution was introduced in 12 via bromination and azidation. The 6‐amino substitution was introduced through direct reaction of 29 with sodium azide. Destrioxyphenylstreptonigrin 2 was twice as active and the 6‐amino‐7‐inethoxy analogue 4 was as active as streptonigrin in a microbiological assay. A 4′‐bromo analogue of 2 was 60% as active as streptonigrin.
Abnormal behavior of nitropyridines in substitution reactions with anions
Authors: Kurita Keisuke , Williams R. L. 
Published: April 2009

AbstractThe reactions of the anions of isonicotinamide and 2‐amino‐5‐nitropyridine with 2‐chloro‐5‐nitropyridine and 3‐nitropyridine were observed to give rise to unexpected substitution products presumably via a radical anion mechanism.
Reaction of carbonyl compounds with dimethyl 3‐ketoglutarate. Synthesis of bicyclic furan derivatives
Authors: Campos Olivia , Cook James M. 
Published: April 2009

AbstractAcid catalyzed reaction of cyelododecane‐1,2‐dione VI with dimethyl,3‐ketoglutarate II led to the formation of methyl (E)‐6,7,8,9,10,11,12,13‐octahydro‐3‐(methoxycarbonyl)cyclododeca‐[b]furan‐2‐aeetate IX, presumably formed through the dihydrodihydroxy furan VIII. This dihydrofuran intermediate VIII was shown to be characteristic of the reaction of 2‐substituted carbonyl‐compounds with 11 for both α‐chlorocyclohexanone and α‐chlorocyclopentanone furnished furans XVIa and XX, respectively, when treated with 11. The effect of dihydrodihydroxy‐furan intermediates on the course of such reactions is discussed.
Analogues azotés de dérivés de l'acide orotique
Authors: Daunis Jacques , Follet Michel 
Published: April 2009

AbstractLes synthéses de deux nouveaux types de composés de structures oxo‐3 thioxo‐5 et dithioxo‐3,5 éthoxycarl)onyl‐6 tétrahydro‐2,3,4,5 triazines‐1,2,4 sont décrites; leur réactivite vis á vis d'agents alkylants et de I'hydrazine est examinée.
Studies on the furan series. Part VII. A preparation of 2,3‐Di(2‐furyl and thienyl)furans
Authors: Pennanen Seppo I. 
Published: April 2009

AbstractFuroin reacts smoothly with dimethyl acetylenedicarboxylate via a Michael addition, which is followed by a dihydrofuran ring formation. After elimination of water the previously unknown 2,3‐di(2‐furyl)furan structure is produced. Thenoin gives a side reaction to yield a fumaric acid derivative in addition to the expected 2,3‐di(2‐thienyl)furan. A mechanism for the side reaction is suggested. The reactivities of the prepared new furan structures towards some oxidation, hydrogenation and electrophilic reagents were determined.
Hétérocycles contenant du phosphore. XXXII. Etude de l'action des phosphorhydrazides sur les orthoesters, l'anhydride acétique et l'acide formique
Authors: Majoral Jean Pierre , Revel Monique , Kraemer Raymond , Germa Héléne , Navech Jacques 
Published: April 2009

AbstractL'action des phosphodi‐ ou trihydrazides sur les orthoesters permet, en général, d'obtenir des tétrahydro‐2,3,4,5 tétrazaphosphorines‐1,2,4,5,3. Cependant, dans certains cas, il y a formation de amino‐4 triazaphospholidines‐1,2,4,3. Les tétrazaphosphorines‐1,2,4,5,3 obtenues présentent parfois une prototropie. La présence de cette prototropie se traduit par une orientation de la réaction de certains de ces composés avec le formaldéhyde ou l'acétone. La structure des différents hétérocycles obtenus est établie par rmn.
Etude de la configuration d'oximes a activité cardiotrope
Authors: Laforest Jacqueline , Thuillier Germaine 
Published: April 2009

AbstractLa configuration des 2 isoméres de thiényl‐2, et furyl‐2, (dichloro‐2,3 methoxy‐4)phényl cétone oxime est déterminée, d'une part en étudiant les déplacements chimiques induits sur les spectres de résonance magnétique nucléaire par la formation d'un complexe avec un chélate de lanthanide et d'autre part par voie chimique. Les résultats obtenus permettent de définir la configuration des 2 isoméres de thiényl‐2, et furyl‐2, (dichloro‐2,3 méthoxy‐4)phényl O‐di‐éthylamino éthyl cétone oxime, composés dont l'activité cardiotrope est remarquable.
Ind‐N‐alkylation of rutaecarpine and synthesis of two novel related heterocyclic ring systems: Indolo[1′,2′:3,4]pyrazo[1,2‐α]quinazoline and indolo[1′,2′:3,4] [1,4] diazepino[ 1,2‐α]quinazoline
Authors: Danieli Bruno , Palrnisano Giovanni 
Published: April 2009

AbstractThe failure to obtain the N‐(13)alkylrutaecarpines (1d,e,f) by heating rutaecarpine (1a) with neat alkyl halides at 120° is discussed in comparison with the facile reaction with methyl iodide. In contrast, with alkyl halide‐potassium carbonate in acetone, the corresponding N‐(13)alkyl‐rutaeearpines (1d‐l) are obtained in good yield. By use of 1,3‐diiodopropane and 1,2‐dibromo‐ethane, this reaction provides a facile route to 12a and 13 which are derivatives of the heretofore unknown indolo[1,2′:3,4]pyrazo[1,2‐α]quinazoline and indolo[1,2 :3,4][1,4]diazepino[1,2‐α]quinazoline ring systems.
Reactivity of the A‐CH=N=NR‐CX‐B System. 1,3,4‐thiadiazoles and Δ2 ‐thiadiazolines
Authors: Werber Giuseppe , Buccheri Francesco , Gentile Manlio , Librici Luigi 
Published: April 2009

AbstractThe reactivity of the magnified image‐ system towards ferric chloride has been investigated. The cyclo‐oxidation reaction led to the formation of 2‐amino‐5‐thenoyl‐1,3,4‐thiadiazoles and 4‐methyl‐5‐imino‐2‐thenoyl‐Δ2‐1,3,4‐thiadiazolines. Their structures were proven spectro‐scopically and chemically (nucleophilic attack and formation of the related 2‐amino‐1,3,4‐thiadiazoles and 4‐methyl‐5‐imino‐Δ2‐1,3,4‐thiadiazolines).
Conversion of the carboxyl group to the corresponding trichloromethyl group in the quinoline series
Authors: Takahashi Kazuyuki , Mitsuhashi Keiryo 
Published: April 2009

AbstractVarious substituted quinaldinic acids were treated with phosphorus pentachloride in an excess of thionyl chloride. Carboxyl groups of quinaldinic acid, 6‐methyl‐, 6‐chloro‐, 4‐phenyl‐ and 4‐(p‐chlorophenyl)quinaldinic acids and benzo[f]quinoline‐3‐carboxylic acid were converted to the trichloromethyl group, while those of 8‐methyl‐, 4‐(3,4‐dichlorophenyl)‐, 4‐(p‐nitrophenyl)‐quinaldinic acids and benzo[h]quinoline‐2‐carboxylic acid were not. The difference is discussed on the basis of the effects of the basicity of ring nitrogen and steric factors.
Methylation and amination of folic acid
Authors: Temple Carroll , Kussner Conrad L. , Montgomery John A. 
Published: April 2009

AbstractThe methylation of folic acid (2) with excess methyl iodide resulted in the formation of dimethyl 1,3‐dimethylfolate (4), whereas, methylation of dimethyl folate (3) with an equimolar amount of methyl iodide gave mainly dimethyl 3‐methylfolate (6). Both 4 and 6 underwent the Dimroth rearrangement in base to give the corresponding 2‐deamino‐2‐methyiamino folic acids 5 and 7, respectively. Amination of 2 with hydroxylamine‐O‐sulfonic acid in dilute base gave a low yield of 3‐amino folic acid (8), which underwent Dimroth rearrangement to give 2‐deamino‐2‐hydrazino folic acid (9) in an acidic, but not a basic, medium.
Synthesis and 270 MHz Nmr structural studies of the isomers of 2,3,5‐trimethyl‐ and 2,3,6‐trimethylmorpholine
Authors: Hernestam Sven , Nilsson Bertil , Stenvall Gillis 
Published: April 2009

AbstractThe four isomers of 2,3,5‐trimethylmorpholine and those of 2,3,6‐trimethylmorpholine have been synthesized from appropriately substituted ethanolamines and separated by means of preparative gas‐liquid chromatography. The configuration of each isomer was determined from 270 MHz FT‐nmr studies of the magnitudes of the methine‐methine and methine‐methylene proton coupling constants. The evaluated chemical shifts of axial methyl groups are discussed.
Synthesis, phosphodiesterase inhibition and antiinflammatory activity of 2‐aryl‐3‐hydroxythieno[2,3‐b]quinoline 1,1‐dioxides. Application of sodium chlorite as a novel reagent for the (Stepwise) oxidation of sulfides to sulfones
Authors: Harrison Ernest A. , Rice Kenner C. , Rogers Michael E. 
Published: April 2009

AbstractSynthesis of five 2‐aryl‐3‐hydroxythieno[2,3‐b]quinoline 1,1‐dioxides (38‐42) from 3‐formylquinoline‐2‐thiol (3) via a facile oxidation‐cyclization sequence is reported. Reaction of appropriate benzyl chlorides with the thiol (3) in the presence of sodium methoxide gave excellent yields of the corresponding benzyl 2‐(3‐formylquinolyl) sulfides (4‐8). Direct oxidation of these sulfides to the corresponding sulfones (23‐27) was effected with excess sodium chlorite in aqueous pyridine. Esterification of these sulfone‐acids followed by brief treatment of the resulting esters 28‐32 with sodium methoxide gave the desired compounds 38‐42 after acidification. The benzyl 2‐(3‐formylquinolyl) sulfides were also selectively oxidized to the corresponding sulfoxides (13‐17). Thus sodium chlorite has proved to be an effective reagent for the stepwise oxidation of sulfides to sulfones. The title compounds were potent inhibitors of cyclic AMP phosphodiesterase, but failed to display significant antiinflammatory effects in the carrageenan rat paw edema test or significant activity in the phenylquinone induced writhing test for analgesia.
A method for nitration of thiazoles
Authors: Grehn Leif 
Published: April 2009

AbstractNitrations of some sensitive thiazole derivatives with trifluoromethanesulfonic acid‐trifluoro‐methanesulfonic anhydride.‐potassium nitrate in 1,2‐dichloroethane gave significantly higher yields of the nitro compounds in comparison with nitrations in sulfuric acid‐nitric acid mixtures.
Condensation of o‐aminophenol and α‐dicarbonyl compounds. Part 1. Benzoxazines
Authors: Belgodere E. , Bossio R. , Parrini V. , Pepino R. 
Published: April 2009

AbstractBy condensation with o‐aminophenol of a series of phenylglyoxal derivatives two species of products were obtained, namely 2‐hydroxy‐(2H)‐1,4‐benzoxazines (I) and 2′ ‐aryl‐2,2′ ‐dibenzoxa‐zolines (II). The structure of compounds I was investigated by ir, uv and pmr spectroscopy and a reaction mechanism was proposed. J. Chem. Soc., 14, 997 (1977)
Reaction of dichloroketene and sulfene with N,N‐disubstituted 6‐amino‐methylene‐b,7,8,9 ‐tetrahydro‐5H‐benzocyclohepten‐5‐ones. Synthesis of 6‐(2,2‐Dichloroethylidene)‐b,7,8,9‐tetrahydro‐5H‐benzocyclohepten‐5‐one and of 5H‐benzo[3,4]cyclohepta[2,l‐b]pyran and 5H‐Benzo[3,4]cyclo‐hepta[1,2‐e]‐1,2‐oxathiin derivatives
Authors: Bignardi Gaetano , Mosti Luisa , Schenone Pietro , Menozzi Giulia 
Published: April 2009

AbstractThe 1,4‐cycloaddition of dichloroketene to N,N‐disubstituted 6‐aminomethylene‐b,7,8,9‐tetra‐hydro‐5H‐benzocyclohepten‐5‐ones afforded N,N‐disubstituted 4‐amino‐3,3‐dichloro‐3,4,6,7‐tetrahydro‐5H‐benzo[3,4]cyclohepta[2,l‐b]pyran‐2‐ones only in the case of aromatic or strong hindering aliphatic N‐substitution. The adducts gave N,N‐disubstituted 4‐amino‐3‐chloro‐b,7‐dihydro‐5H‐benzo[3,4]cyclohepta[2,l‐b]pyran‐2‐ones by dehydrochlorination with collidine. Upon chromatography on neutral alumina, two products were instead isolated in the case of usual aliphatic N‐substitution (diethylamine, piperidine), namely 6‐(2,2‐dichloroethylidene)‐6,7,8,9‐tetrahydro‐5H‐benzocyclohepten‐5‐one and the dehydrochlorinated 2‐pyrone; this latter was the sole product in the case of pyrrolidine substitution. The 1,4‐cycloaddition of sulfene occurred readily to give N,N‐disubstituted 4‐amino‐3,4,6,7‐tetrahydro‐5H‐benzo[3,4]cyclohepta‐[1,2‐e]‐1,2‐oxathiin 2,2‐dioxidesin the case of both aliphatic and partially aromatic N‐substitution.
1,3‐Dioxolan‐4‐ones and 1,3‐oxathiolan‐5‐ones. Configuration of cis and trans isomers
Authors: Pilgram Kurt , Zupan Mike 
Published: April 2009

AbstractThe attempted acid‐catalyzed azeotropic removal of water from a mixture containing lactamide and chloral in refluxing toluene lead to the elimination of ammonia; both cis‐ and trans‐5‐methyi‐2‐(trichloromethyl)‐1,3‐dioxolan‐4‐one were isolated. A number of 1,3‐dioxolan‐4‐ones and 1,3‐oxathiolan‐5‐ones were obtained by cyclodehydration of aldehydes with α‐hydroxy‐ and α‐mercapto‐carboxylic acids in the presence of boron trifluoride etherate. Geometric isomers were separated, and their configurations were determined by nuclear magnetic resonance.
Azido‐tetrazolo isomerizations of some thiazolopyridines
Authors: Petrič A. , Stanovnik B. , Tišler M. 
Published: April 2009

Abstract2‐Azidothiazolo[5,4‐b]pyridine and 2‐azidothiazolo[4,5‐c]pyridine were synthesized. Azido‐tetrazolo isomerizations of these compounds were investigated and in both cases also the tetrazolo form could be obtained. In solution, equilibria at different temperatures were determined.