bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation of keto‐s‐phenylthioxime of [23]cyclophane‐1,2‐dione. Re‐visited contraction of 1,2,5‐thiadiazole ring incorporated in a [23]cyclophane bridge by phenylmagnesium bromide
Authors: Hatta Taizo , Mataka Shuntaro , Tashiro Masashi , Numano Katsutoshi , Tanimoto Satoshi , Tori‐I Akiyoshi 
Published: March 2009

Abstract[23]Paracyclophane derivative 3 of keto‐S‐phenylthioxime which is the hydrolyzed product of the hypothetical intermediate in the reaction of 1,2,5‐thiadiazole with organometallic reagents, was obtained, together with diketone 1, in the reaction of 1,2,5‐thiadiazolo[23]paracyclophane 2 with two equivalents of phenylmagnesium bromide. Contrary, [23]metacyclophane 7 gave only diketone 12 in the reaction with phenylmagnesium bromide under the same conditions.
The synthesis and transformations of 2H‐naphtho‐[1,2‐b]pyran‐2‐one derivatives. Naphtho[2′,1′:5,6]‐pyrano[3,4‐d][1,3]oxazines and naphtho[1′,2′:5,6]pyrano[3,4‐d]‐pyrimidines, derivatives of two new heterocyclic systems
Authors: Fajgelj Simona , Stanovnik Branko , Tišler Miha 
Published: March 2009

Abstract1,4‐Naphthoquinone (1) was transformed with alkyl 2‐aminofumarates 2 into 2H‐naphtho[1,2‐b]pyran‐2‐ones 3 and 4, which served as intermediates in the synthesis of 7, 8 and 13, which are derivatives of two new heterocyclic systems: naphtho[2′,1′:5,6]pyrano[3,4‐d][1,3]oxazine and naphtho[1′,2′:5,6]pyrano[3,4‐d]pyrimidine.
Hydroxylation of 5H‐3‐Oxo‐2,3,6,7,8,9‐hexahydroimidazo[1,2‐a]azepine derivatives by molecular oxygen
Authors: Campagna Francesco , Carotti Angelo , Casini Giovanni 
Published: March 2009

AbstractO‐Methylcaprolactim 3 reacts in hot dimethylsulfoxide with α‐amino acids 4 to give 5H‐3‐oxo‐2,3,6,7,8,9‐hexahydroimidazo[1,2‐a]azepines 6 and, unexpectedly, hydroxylated derivatives 7a,c and 8c. The structures of the hydroxylated compounds have been elucidated by spectroscopic means and, when necessary, further confirmed by an independent unequivocal synthesis. The formation of 7 as well as the isomerization of 7c to 8c are discussed in detail.
Protected 2‐indoleacetaldehyde derivatives from 2‐acylindoles
Authors: Bonjoch Josep , Linares Ana , Pérez M.‐Lluïsa , Bosch Joan 
Published: March 2009

AbstractThe conversion of tetracyclic 2‐acylindoles 1 to the protected 2‐indoleacetaldehydes 4 and 6 is reported. 2‐Indoleacetaldehydes 5 undergo oxidation to the corresponding 2‐acylindoles 1.
Pyrrolopyridazine nucleosides. The synthesis of certain 1‐β‐D‐ribofuranosyl‐1H‐pyrrolo[2,3‐d]pyridazin‐4(5H)‐ones
Authors: Girgis Nabih S. , Robins Roland K. , Cottam Howard B. 
Published: March 2009

AbstractNucleosides of pyrrolo[2,3‐d]pyridazin‐4(5H)‐ones were prepared by the single‐phase sodium salt glycosylation of appropriately functionalized pyrrole precursors. The glycosylation of the sodium salt of ethyl 4,5‐dichloro‐2‐formyl‐1H‐pyrrole‐3‐carboxylate (4), or its azomethino derivative 7, with 1‐bromo‐2,3,5‐tri‐O‐benzoyl‐D‐ribofuranose in acetonitrile afforded the corresponding substituted pyrrole nucleosides ethyl 4,5‐dichloro‐2‐formyl‐1‐(2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranosyl)‐1H‐pyrrole‐3‐carboxylate (5) and ethyl 4,5‐dichloro‐2‐phenylazomethino‐1‐(2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranosyl)‐1H‐pyrrole‐3‐carboxylate (8), respectively. The latter, upon treatment with hydrazine, afforded the annulated product 2,3‐dichloro‐1‐β‐D‐ribofuranosyl‐1H‐pyrrolo[2,3‐d]pyridazin‐4(5H)‐one (6), in good yield. The unsubstituted analog 1‐β‐D‐ribofuranosyl‐1H‐pyrrolo[2,3‐d]pyridazin‐4(5H)‐one (9), was obtained upon catalytic dehalogenation of 6. This report represents the first example of the synthesis of nucleosides of pyrrolopyridazines.
On the mechanism of thermal decomposition of 4‐alkyl‐5‐sulfonylimino‐Δ2‐1,2,3,4‐thiatriazolines
Authors: L'abbé Gerrit , Bosman Joris 
Published: March 2009

AbstractThe kinetics of the thermal decomposition of several sulfonyl substituted thiatriazolinimines 1a‐g were investigated in different solvents both in the presence and in the absence of trapping reagents. The first‐order rate constants observed in all cases, are dependent on the inductive effect of the sulfonyl substituent (R), as well as on solvent polarity, but independent on the nature and concentration of the co‐reagent. These results, and the low activation energy, are rationalized by assuming an anchimeric assistance of the sulfonyl group during thermolysis. This would give the intermediate 7, which collapses to the thiaziridinimine 2 before being trapped by the co‐reagent.
Synthesis of 8‐amino‐4‐methylthio‐6‐methyl‐2‐(β‐D‐ribofuranosyl)‐2,6‐dihydro‐1,2,3,5,6,7‐hexaazaacenaphthylene and an unusual reductive ring‐opening of the 1,2,3,5,6,7‐hexaazaacenaphthylene ring system
Authors: Kawasaki Andrew M. , Townsend Leroy B. 
Published: March 2009

AbstractThe tricyclic nucleoside 8‐amino‐4‐methylthio‐6‐methyl‐2‐(β‐D‐ribofuranosyl)‐1,2,3,5,6,7‐hexaazaacenaphthylene (3) was synthesized from 3‐cyano‐4,6‐bis(methylthio)‐1‐(β‐D‐ribofuranosyl)pyrazolo[3,4‐d]pyrimidine (1). Attempts to synthesize 8‐amino‐6‐methyl‐2‐(β‐D‐ribofuranosyl)‐1H‐2,6‐dihydro‐1,2,3,5,6,7‐hexaazaacenaphthylene (5) ([an aza analog of 6‐amino‐4‐methyl‐8‐(β‐D‐ribofuranosyl)‐1,3,4,5,8‐pentaazaacenaphthylene (TCN)], which is a potent antitumor agent), by the treatment of 3 with Raney nickel did not afford the desired aza analog of TCN. Instead, it was established that a reductive cleavage of the pyridazine moiety of 3 had occurred to give 4‐methylamino‐6‐methylthio‐1‐(β‐D‐ribofuranosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine‐3‐carboxamidine (6). Assuming that solubility was a problem in the reductive step, the isopropylidene derivative of 3, 8‐amino‐6‐methyl‐4‐methylthio‐2‐(2,3‐O‐isopropylidene‐β‐D‐ribofuranosyl)‐2,6‐dihydro‐1,2,3,5,6,7‐hexaazaacenaphthylene (8), was treated with Raney nickel, only to observe that a similar reductive ring cleavage of 8 had occurred to afford 4‐methylamino‐6‐methylthio‐1‐(2,3‐O‐isopropylidene‐β‐D‐ribofuranosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine‐3‐carboxamidine (10) and 4‐methylamino‐1‐(2,3‐O‐isopropylidene‐β‐D‐ribofuranosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine‐3‐carboxamidine (11). Structural assignments for all products were established by physico‐chemical procedures.
A study on m‐chloroperbenzoic acid and lead tetraacetate oxidation of some 1‐aroyl‐4,5‐dihydro‐4,4‐dimethyl‐5‐methylene‐1H‐pyrazoles
Authors: Mitkidou Sophia , Stephanidou‐Stephanatou Julia 
Published: March 2009

Abstract1‐Aroyl‐4,5‐dihydro‐5‐methylene‐1H‐pyrazoles 1 are converted upon oxidation with m‐chloroperbenzoic acid to the pyrazolones 2. The same aroyl enamides 1 are also oxidized with LTA to form the acetoxy derivatives 7 and 8. The reaction mechanisms are discussed.
Chemistry of thienopyridines. XXXIX. Synthesis of benzothieno[2,3‐h]isoquinoline and related studies
Authors: Klemm L. H. , Severns Bryon , Wynberg Hans 
Published: March 2009

AbstractBenzo[b]thiophene‐2‐carboxaldehyde undergoes condensation with 4‐methylpyridine and with 2‐methylquinoline to produce trans‐diarylethenes (52% and 76%, respectively). The former alkene photocyclizes in cyclohexane to yield [1]benzo[2,3‐h]isoquinoline (35%), while the latter alkene does not give successful, analogous cyclization.
Some fatty acids having an O‐heterocycle in their terminal positions. II. ω‐(3‐Coumarinyl)alkanoic acids and ω‐(2‐chromonyl)alkanoic acids
Authors: Yamaguchi Seiji , Saitoh Miyuki , Kawase Yoshiyuki 
Published: March 2009

AbstractSome ω‐3‐coumarinyl)alkanoic acids 1a, n = 3‐6 were synthesized by cyclization of corresponding ethyl o‐formylphenyl alkanedioate 3 with DBU followed by hydrolysis. By a similar cyclization, some ω‐(2‐chromonyl)alkanoic acids 2a, n = 3‐6 were also obtained from the cyclization of corresponding o‐acetylphenyl ethyl alkanedioate 4.
Nouveaux hétérocycles à partir d'esters cyaniques. Arylimino‐2 et arylamino‐2 4H‐benzoxazin‐1,3 ones‐4, leur tautomérie et étude de leur alkylation régiosélective
Authors: Hedayatullah Mir , Lion Claude , Pailler Jacques 
Published: March 2009

AbstractUne nouvelle série de benzoxazinones substituées en position 2 a été obtenue par action d'amines aromatiques primaires sur les cyanates d'aryle renfermant en position ortho un groupe éthoxycarbonyle. L'étude de leurs spectres ir et de rmn a montré que leur forme tautomère prépondérante correspond à une structure d'arylimino‐2 4H‐benzoxazin‐1,3 one‐4. La synthèse régiosélective de leurs dérivés alkylés sur les azotes cyclique et extracyclique, par alkylation en milieu d'éthanol, de diméthylformamide et en catalyse par transfert de phase solide‐liquide a été réalisée.
Synthesis and 1H NMR characterization of substituted 1‐amino‐9‐imino‐4‐nitro‐9,10‐dihydr oacridines as potential antitumor agents
Authors: Cholody Wieslaw M. , Konopa Jerzy , Antonini Ippolito , Martelli Sante 
Published: March 2009

AbstractA convenient method for the synthesis of unsubstituted and substituted 1‐amino‐9‐imino‐4‐nitro‐9,10‐dihydroacridines, 9 and 10, respectively, is reported. Their 1H nmr data are reported and discussed in order to confirm the imino tautomeric structure.
Polycyclic N‐hetero compounds. XXXIV. Syntheses and evaluation of antidepressive activity of benzofuro‐[2,3‐e]imidazo[1,2‐c]pyrimidines and their precursors
Authors: Hirota Takashi , Sasaki Kenji , Tashima Yohsuke , Nakayama Taiji 
Published: March 2009

AbstractSyntheses of 2,3‐dihydrobenzofuro[2,3‐e]imidazo[1,2‐c]pyrimidine and its 5‐substituted derivatives, corresponding to B‐nor‐6‐oxa‐11,13,15‐triazasteroids, are described. These products and their precursors were screened to evaluate the antidepressive activity.
Acid‐catalysed rearrangement of 1‐oximinoacridine‐1,9‐diones. synthesis of novel 4,5‐dihydro‐3H‐isoxazolo[3,4,5‐kl]acridines
Authors: Venugopalan B. , Bapat C. P. , De Souza E. P. , De Souza N. J. 
Published: March 2009

AbstractA polyphosphoric acid (PPA) catalysed internal cyclization of 1‐oximinoacridine‐1,9‐diones 2 to novel isoxazolo[3,4,5‐kl]acridines 3 is reported. Some of the compounds displayed antimalarial activity in animal models.
Synthesis of α‐(aminomethylene)‐9H‐purine‐6‐acetic acid derivatives
Authors: Hamamichi Norimitsu , Miyasaka Tadashi 
Published: March 2009

Abstractα‐(Aminornethylene)‐9H‐purine‐6‐acetamide (3a) and the corresponding ethyl acetate 9 have been synthesized by catalytic hydrogenation of 6‐cyanomethylenepurine derivatives 2 and 7 which were obtained by the substitution of 6‐chloropurine derivatives with α‐cyanoacetamide and ethyl cyanoacetate, respectively. Substitution of α‐(aminomethylene)‐9‐(tetrahydrofuran)‐9H‐purine‐6‐acetamide (3b) with amines gave the corresponding N‐alkyl‐ and N‐arylamines 5, which were treated with acid to give N‐substituted α‐(aminomethylene)‐9H‐purine‐6‐acetamides 6. Substitution of 9 with amines gave the corresponding N‐alkyl‐ and N‐aryl substituted amines 10.
1,3‐Dipolar cycloaddition reactions of nitrile oxides and nitrile imines with 2‐methoxyvinyl phenyl ketone
Authors: Coutouli‐Argyropoulou E. , Thessalonikeos E. 
Published: March 2009

AbstractNitrile oxides react regioselectively with 2‐methoxyvinyl phenyl ketone 1 to give 4‐benzoylisoxazoles 4 via elimination of methanol from the primary cycloadducts 3. After heating with an excess of nitrile oxide bis‐cycloadducts 5 were also formed. Reactions of nitrile imines with 1 are less regioselective yielding both 4‐benzoylpyrazoles 9 and 5‐benzoytpyrazoles 10, whereas no bis‐cycloadducts were isolated.
Ring transformation of 4‐amino‐1H‐1,5‐benzodiazepine‐3‐carbonitrile and ethyl 4‐amino‐1H‐1,5‐benzodiazepine‐3‐carboxylate into benzimidazole derivatives with amines
Authors: Aotsuka Tomoji , Okamoto Yoshihisa , Takagi Kaname , Hubert‐Habart Michel 
Published: March 2009

AbstractThe ring contraction of 4‐ammo‐1H‐1,5‐benzodiazepine‐3‐carbonitrile hydrochloride 1 and ethyl 4‐amino‐1H‐1,5‐benzodiazepine‐3‐carboxylate hydrochloride 2 with aromatic primary amines into benzimidazole derivatives 3 and 4 was readily accomplished by heating in methanol. Benzodiazepine 1 also reacted with methylamine and ethylamine at about 40° to give ring‐opened amine adducts 7 which were recyclized to 1 with hydrochloric acid.
Condensed heterocyclic lactams. I. Study on the cyclization methods resulting in 4‐aryl‐3,4‐dihydroquinolin‐2(1H)‐ones
Authors: Hazai László , Deák Gyula , Sohár Pál , Tóth Gábor , Tamás József 
Published: March 2009

AbstractCyclization reactions with polyphosphoric acid of 3‐aryl‐3‐hydroxypropionanilides carrying a p‐nitro‐ 7a or p‐amino substituent 10 on the C‐3 phenyl group were investigated. In the case of p‐nitro substitution the preferred reaction is, instead of cyclization, the elimination of water to give the corresponding cinnamic acid derivative. On the other hand, reaction of the p‐amino‐substituted analogue gave the new compound 4‐(4‐aminophenyl)‐3,4‐dihydroquinolin‐2(1H)‐one (2b) in a good yield. The intermediate product of the cyclization was isolated and its structure established.
Stepwise approach to the 2,3‐dihydroimidazo[1,2‐a]pyridine and 5‐oxo‐1,2,3,5‐tetrahydroimidazo[1,2‐a]pyridine ring systems
Authors: Podhorez David E. 
Published: March 2009

AbstractThe syntheses of 2,3‐dihydro‐8‐fluoro‐6‐trifluoromethylimidazo[1,2‐a]pyridine‐3‐carbonitrile (2), 8‐fluoro‐6‐trifluoromethylimidazo[1,2‐a]pyridine‐3‐carbonitrile (9) and 5‐oxo‐8‐trifluoromethyl‐1,2,3,5‐tetrahydroimidazo[1,2‐a]pyridine‐3‐carbonitrile (3) are described. These compounds are constructed in a stepwise approach starting from the properly substituted 2‐halopyridines.
Studies on polycyclic thiaarenes: Part II. An improved synthesis of phenanthro[1,2‐b]thiophene and a synthesis of acenaphtho[1,2‐b]naphtho‐[2,3‐d]thiophene, a novel polynuclear thiaarene
Authors: Kar Gandhi K. , Karmakar Arun C. , Ray Jayanta K. 
Published: March 2009

AbstractAn improved synthesis of phenanthro[1,2‐b]thiophene (6) from 1‐chloro‐3,4‐dihydrophenanthrene‐2‐aldehyde (2) by condensation with thioglycolate followed by hydrolysis, decarboxylation and dehydrogenation is described. A new polycyclic thiophene derivative 14 has also been prepared from acenaphthothiophene (7) by Friedel‐Craft's reaction with phthalic anhydride followed by lactonisation of the keto carboxylic acid 9 and then reduction and finally cyclisation of the resultant aldehyde 13.
Deoxydative substitution of pyridine 1‐oxides by thiols. Part XX. Reactions of (2, 3, and 4‐phenyl)‐, 3‐acetamido‐, 3‐bromo‐, 3‐acetoxy‐, 3‐ethoxypyridine 1‐oxides with 1‐adamantanethiol in acetic anhydride
Authors: Prachayasittikul Supaluk , Doss George , Bauer Ludwig 
Published: March 2009

AbstractSubstitutions of 2, 3, and 4‐substituted pyridine 1‐oxides by 1‐adamantanethiol in acetic anhydride takes place at available α‐, to a lesser degree at β‐, and rarely at γ‐ring carbons. It was found that 2‐phenylpyridine 1‐oxide produces a mixture of 5‐ and 6‐(1‐adamantylthio)‐2‐phenylpyridines, and 4‐phenylpyridine 1‐oxide a mixture of 2‐ and 3‐isomeric sulfides. Substitutions of the 1‐oxides of 3‐phenyl‐, 3‐acetamido‐, 3‐acetoxy‐, 3‐bromo‐, and 3‐ethoxypyridine by 1‐adamantanethiol in acetic anhydride led to mixtures consisting predominantly of 2‐ and 6‐sulfide, and to a lesser extent, the 5‐sulfide. When triethylamine is present in otherwise identical reaction mixtures, the ratio of α to β‐sulfides increases. From the reactions of 3‐ and 4‐phenylpyridine 1‐oxides, there were isolated some N‐acetyl hydroxy (or acetoxy) 1‐adamantylthio substituted 1,2,3,4‐and 1,2,3,6‐tetrahydropyridines, whose structures are discussed.
Intramolecular photocyclization of N‐[(2‐haloaryl)methyl]pyridinium and n‐(arylmethyl)‐2‐halopyridinium salts
Authors: Park Y.‐T. , Joo C.‐H. , Choi C.‐D. , Park K.‐S. 
Published: March 2009

AbstractVarious N‐[(2‐haloaryl)methyl]pyridinium, N‐(arylmethyl)‐2‐halopyridinium and N‐(2‐halobenzyl)iso‐quinolinium salts have been synthesized and their intramolecular photocyclization reactions studied. Upon irradiation the aqueous solution of N‐[(2‐haloaryl)methyl]pyridinium, and N‐arylmethyl‐2‐halopyridinium salts 1, 2 were cyclized to give isoindolium salts. In contrast to the pyridinium salts 1, 2, the aqueous solution of N‐(2‐halobenzyl)isoquinolinium salts 3 appear not to undergo photocyclization. N‐Benzyl‐2‐chloropyridinium salts 1c is more reactive than N‐(2‐chlorobenzyl)pyridinium salt 1a in the photocyclization. N‐(2‐Chlorobenzyl)‐2‐chloropyridinium salt 1d is three times more reactive than 1c. A mechanism of π‐complex formation of the halogen moiety of the pyridinium ring with the phenyl ring is suggested for the reactive pyridinium salt. The triplet energy of the isoquinolinium salts 3 is tool low to photocyclize.
6‐Substituted‐9‐(3‐formamidobenzyl)‐9H‐purines. Benzodiazepine receptor binding activity
Authors: Kelley James L. , Mclean Ed W. , Ferris Robert M. , Howard James L. 
Published: March 2009

AbstractA series of 6‐substituted‐9‐(3‐formamidobenzyl)purines were synthesized and studied for benzodiazepine receptor (BZR) binding activity. Most of the target compounds were prepared by reaction of 6‐chloro‐9‐(3‐formamidobenzyl)‐9H‐purine (17) with the appropriate amine, alcohol or other nucleophilic reagent. Alternatively, the 6‐cyclopropylaminopurine 5 was synthesized via the nitrobenzyl precursor 22, and the 6‐alkyl‐thiopurines 14 and 15 were prepared by alkylation of the appropriate purine with 3‐formamidobenzyl bromide. Purines with a variety of 6‐substituents retained potent BZR binding properties, although certain bulky 6‐substituents led to compounds with diminished activity. None of the compounds exhibited significant activity on a modified Geller‐Seifter Conflict schedule.
Carbazoledioxazines having long alkyl groups. 2. Synthesis of carbazoledioxazines with angular type structure
Authors: Ikeda Masaaki , Kitahara Kiyoshi , Nishi Hisao 
Published: March 2009

AbstractCarbazoledioxazines with an angular type structure (5,15‐dialkyl‐7,17‐dialkyloxy‐9,19‐dichloro‐5,15‐dihydrodiindolo[2,3‐c:2′,3′‐n]triphenodioxazines) were selectively synthesized by electrochemical oxidative ring closure of precursors (2,5‐bis(9‐alkyl‐2‐alkyloxy‐3‐carbazolylamino)‐3,6‐dichloro‐1,4‐benzoquinones). The structure was confirmed by 1H‐nmr and other instrumental analyses. Their thermal properties and solubilities were investigated and were compared with those of carbazoledioxazines with a linear type structure.
Reaction of enaminones with carbon disulfide: Synthesis of heterocycles using enamino dithiocarboxylates
Authors: Tominaga Yoshinori , Okuda Hiroto , Kohra Shinya , Mazume Hisako 
Published: March 2009

AbstractReaction of various types of enaminones, which are prepared by the condensation of 1,3‐dicarbonyl compounds with aromatic amines, with carbon disulfide in the presence of sodium hydroxide as the base in dimethyl sulfoxide to give the corresponding enamino dithiocarboxylates, 1,3‐thiazines and trithiones. Enamino dithiocarboxylates are cyclized under refluxing in diphenyl ether to give the fused quinoline derivatives. The reaction of 6‐arylamino‐1,3‐dimethyluracils with excess carbon disulfide in the presence of sodium hydroxide and subsequent methylation with dimethyl sulfate gave directly the corresponding 1,3‐dimethyl‐5‐methylthiopyrimido[4,5‐b]quinoline‐2,4(1H,3H)‐diones.
Photocyclization reactions. Part 2 Synthesis of dihydrobenzofuranols using photocyclization of ethyl 2‐formylphenoxyacetates and ethyl 2‐acetylphenoxyacetates
Authors: Horaguchi Takaaki , Tsukada Chikara , Hasegawa Eietsu , Shimizu Takahachi , Suzuki Tsuneo , Tanemura Kiyoshi 
Published: March 2009

AbstractPhotocyclization reactions were carried out on ethyl 2‐formylphenoxyacetates 1a‐e and ethyl 2‐acetylphenoxyacetates 2a‐e in acetonitrile. Irradiation of 1a‐e gave dihydrobenzofuranols 3 in 20–46% yields. Similarly, irradiation of 2a‐e afforded dihydrobenzofuranols 6 and their derivatives 7, 8 in 40–86% yields. Substituent effects on photocyclization and reaction pathways are discussed.
The wolff‐kishner reduction of 2‐acetonyl pyrazines and pyridines. A novel rearrangement
Authors: Paine John B. 
Published: March 2009

AbstractWolff‐Kishner reduction of 1‐(6‐methylpyrazin‐2‐yl)‐2‐propanone leads to the formation of 2‐isopropyl‐6‐methylpyrazine (2a), in addition to the expected 6‐methyl‐2‐n‐propylpyrazine. The by‐product 2a is suggested to arise via a spirocyclopropylidene aza‐anion, which serves as a conduit between the initial less‐stable secondary 1‐(2‐pyrazinyl)‐2‐propyl carbanion and the more stable primary 2‐(2‐pyrazinyl)‐1‐propyl carbanion. Similar results were observed for the 1‐(3‐methylpyrazin‐2‐yl) and 1‐(6‐methylpyridin‐2‐yl)‐2‐propanones. The extent of by‐product formation diminished in the pyridine ring system. Electrophilic activation of the ring appears essential since the benzene analog phenylacetone gave no detectable cumene under identical reaction conditions.
Medium‐sized heterocycles: Synthesis of a 2,10‐Bis(alkoxycarbonyl)‐substituted 6‐Oxo‐12H‐dibenzo[d,g][1,3,2]dioxaphosphocin
Authors: Pastor Stephen D. , Spivack John D. 
Published: March 2009

AbstractThe synthesis and characterization of a 2,10‐bis(alkoxycarbonyl)‐substituted 6‐oxo‐12H‐dibenzo[d,g][1,3,2]‐dioxaphosphocin, 6, is described. The lack of an observable 5JHP coupling of phosphorus to the downfield C‐12 methylene proton and the observation of a 2JHCH geminal coupling constant of 14 Hz suggest that the conformation of 6 in solution is not solely a boat‐chair conformation, but may involve a rapid equilibrium of the boat‐chair with either a boat or twist‐boat conformation.
Bond‐switch rearrangement of 3‐oxo‐Δ4‐1,2,4‐thiadiazolin‐5‐yl ureas
Authors: L'Abbé Gerrit , Albrecht Ernestine , Toppet Suzanne 
Published: March 2009

Abstract5‐Amino‐3‐oxo‐Δ4‐1,2,4‐thiadiazolines 5a,b react with isocyanates to yield 1,2,4‐thiadiazolidine derivatives 9a‐d via bond switching of the corresponding isomers 7. The same type of products 9e‐m was obtained by treatment of 5‐amino‐1,2,3,4‐thiatriazoles 6a‐d with two equivalents of isocyanate.
Novel reaction of carbon suboxide. Synthesis of 6‐amino‐4‐hydroxy‐2(1H)‐pyridone derivatives
Authors: Bonsignore Leonardo , Cocco Maria Teresa , Loy Giuseppe , Onnis Valentina 
Published: March 2009

AbstractThe reaction of 2‐cyanoacetamidines 1 with carbon suboxide 2 afforded 6‐amino‐4‐hydroxy‐2(1H)‐pyri‐dones 4. Compounds 4 were also obtained by reaction of amidines 1 and 2,4,6‐trichlorophenylmalonates 3.
Chemistry of coumarins. Thermal reactions of 4‐chloro‐3‐coumarinyl N,N‐dialkyldithiocarbamates and 3‐nitro‐4‐coumarinyl N‐phenyldithiocarbamate
Authors: Tabaković K. , Tabaković I. 
Published: March 2009

AbstractThe thermal reactions of 4‐chloro‐3‐coumarinyl N,N‐dialkyldithiocarbamates 2–4 and 3‐nitro‐4‐coumarinyl N‐phenyldithiocarbamate, 9, afforded the novel heterocyclic systems, e.g. bis‐6H‐1‐benzopyrano[4,3‐b]1,4]dithiin, 7, and bis‐6H‐1‐benzopyrano[4,3‐b][1,4]thiazine, 14. A possible mechanism of the formation of the reaction products is discussed.
Synthesis of 1‐aryl‐5‐arylazo‐3‐phenylsulfonylpyrazol‐4‐ols from 1‐chloro‐3‐phenylsulfonyl‐2‐propanone
Authors: Takahashi Masahiko , Oshida Takeshi 
Published: March 2009

AbstractTreatment of 1‐chloro‐3‐phenylsulfonyl‐2‐propanone (2) with arenediazonium chlorides gave 1‐arylhydrazono‐3‐chloro‐1‐phenylsulfonyl‐2‐propanones 4, which were cyclized in the presence of sodium acetate to 1‐aryl‐3‐phenylsulfonylpyrazol‐4‐ols 5B. Further treatment of 5B with arenediazonium chlorides yielded 1‐aryl‐5‐arylazo‐3‐phenylsulfonylpyrazol‐4‐ols.
Reduction of 1,3,4,6‐tetrakis(alkylthio)thieno‐[3,4‐c]thiophenes with sodium or sodium anthracenide leading to the cleavage of the alkyl‐sulfur bond
Authors: Tsubouchi Akira , Matsumura Noboru , Inoue Hiroo 
Published: March 2009

AbstractThe reaction of 1,3,4,6‐tetrakis(alkylthio)thieno[3,4‐c]thiophenes 1 with sodium or sodium anthracenide in hexamethylphosphoric triamide (HMPA) gave thieno[3,4‐c]thiophene‐1(3H)‐thiones 2 by the cleavage of the alkyl‐sulfur bond through the intermediary formation of their radical anions.