bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of α‐carboxy‐γ‐butyrolactones by rearrangement of capto‐dative cyclopropanes on silica surfaces
Authors: Alonso Miguel E. , Gómez Matilde , De Sierraalta Sarah P. , Patricia Jano S. 
Published: March 2009

AbstractThe rearrangement of some cyclopropanes featuring electron‐withdrawing and electron releasing substitu‐ents on vicinal carbons of the trimethylene ring to α‐carboxy‐γ‐lactones upon contact with silica gel at room temperature has been discovered. One or two alkyl ester groups were chosen as electron attractor substitu‐ents while one or two cyclopropyl units were used for the release of electron density. It was observed that the lactone forming process is strongly dependent upon these substituents to the extent that only two ester groups and at least one cyclopropane will confer enough vulnerability to the tetra‐substituted cyclopropane for the rearrangement to take place. A comparative study of the lactonization by means of contact with silica and alkaline hydrolysis was performed and some mechanistic considerations are put forth.
4‐Hydroxycoumarin/2‐hydroxychromone tautomerism: Infrared spectra of 2‐13c and 3‐D labeled 4‐hydroxycoumarin and its anion
Authors: Obaseki Andrew O. , Porter William R. , Trager William F. 
Published: March 2009

AbstractBands with primarily v (C=O) and v (C=O) character in the spectra of 4‐hydroxycoumarin and its anion were identified by isotopic substitution with either 13C or deuterium. Two bands of each type were found for spectra of 4‐hydroxycoumarin in solution in chloroform, dioxane, or dimethylsulfoxide, with v (C=O) at 1704–1733 cm−1 and ∼ 1567 cm−1. Two bands, at 1618 and 1559 cm−1, are associated with v (C=C) in the spectrum of crystalline 4‐hydroxycoumarin monohydrate, but only a single v (C=O) band at ∼ 1655 cm−1 was observed. Anhydrous 4‐hydroxycoumarin has v (C=O) bands at ∼ 1700 cm−1 and a shoulder at ∼ 1670 cm−1. The strong band at 1660 cm−1 in the spectrum of 4‐hydroxycommarin anion in dimethylsulfoxide solution is due to a delocalized v (O = C = O) vibration, whereas the band at 1555 cm−1 has partial v (C=C) character and involves C(3) but not C(2), supporting a fully delocalized char structure for the anion. No evidence for the existence of the 2‐hydroxychromone tautomer was found, except in the case of anhydrous 4‐hydroxycoumarin in the solid state.
Thiophene systems. 7. Pyrido[3,2‐b]thieno[3,4‐e][1,4]diazepine derivatives with potential cns activity
Authors: Press Jeffery B. , Hofmann Corris M. , Wiegand Gretchen E. , Safir Sidney R. 
Published: March 2009

AbstractPyrido[3,2‐b]thieno[3,4‐e][1,4]diazepines (1a‐d) were synthesized to investigate their potential CNS activity. Synthesis of the desired ring system was effected by condensation of 2,3‐diaminopyridine (3) with methyl tetrahydro‐4‐oxo‐3‐thiophenecarboxylate (4). Structural assignment of the major condensation product 5 was determined by comparison of 1H nmr absorptions of 5 with those of related methyl lactam derivatives 11 and 14. A discussion of the possible mechanism leading to 5 in preference to isomeric lactam 6 is presented. Biological evaluation of 1a‐d revealed no interesting properties.
Studies on pyrazines.7. The synthesis of 5‐chloropyrazinecarboxylic acid
Authors: Sato Nobuhiro , Arai Shinji 
Published: March 2009

AbstractThe titled carboxylic acid (1) was prepared by condensation of 2‐furylglyoxal with aminoacetamide followed by chlorination of the resulting 2‐hydroxy‐5‐(2′‐furyl)pyrazine (2) and permanganate oxidation. The acid was further converted into methyl ester and 5‐hydroxypyrazinecarboxylic acid.
Reissert compound studies. XLIII. The pyrido[2,3‐b]pyrazine reissert compound
Authors: Veeraraghavan S. , Popp F. D. 
Published: March 2009

AbstractBoth pyrido[2,3‐b]pyrazine (5‐azaquinoxaline) and 2,3‐dimethyl‐5‐azaquinoxaline undergo Reissert compound formation across the 5,6‐position.
Unsymmetrically substituted furoxans. VII. A 13C NMR study of a series of isomeric pairs of furoxans and the structure of the two isomeric chloro‐phenyl‐furoxans
Authors: Calvino R. , Fruttero R. , Gasco A. , Mortarini V. , Aime S. 
Published: March 2009

AbstractThe structure of two isomeric chloro(phenyl)furoxans is proposed by comparison of their 13C nmr spectra with those of several unsymmetrically substituted furoxans and related furazans.
Réaction des carbanions maloniques sur le S‐méthyl ϵ‐thiocaprolactime
Authors: Lhommet Gérard , Richaud Marie Geneviève , Maitte Pierre 
Published: March 2009

AbstractLe S‐méthyl ϵ‐thiocaprolactime réagit avec des composés a methylene actif comme les β‐dicétones, β‐cito‐esters ou quelques malonates. Nous montrons que le S‐méthyl ϵ‐thiocaprolactime est une meilleure forme ac‐tivee de la fonction amide que le O‐méthyl ϵ‐caprolactime.
4‐Hydroxycoumarin/2‐hydroxychromone tautomerism: Infrared spectra of 3‐substituted‐2‐13c‐4‐hydroxycoumarins
Authors: Porter William R. , Trager William F. 
Published: March 2009

AbstractBy isotopic replacement of the carbonyl carbon with 13C, the CO stretching frequency was identified as the highest frequency strongly absorbing band in the 1550–1750 cm−1 region of the infrared spectra of several 3‐substituted 4‐hydroxycoumarins and 3‐substituted 4‐alkoxycoumarins. The compounds selected for study were either known to crystallize as the coumarin tautomeric form by x‐ray diffraction studies or were congeners of such compounds. The carbonyl band varied from 1664 cm−1 in inter‐ or intramolecularly hydrogen bonded derivatives to 1718 cm−1.
Intramolecular acylation of 3‐oxo‐2‐piperidine‐propionic acid derivatives. Synthesis of hexahydro‐2‐oxopyrano[3,2‐b]pyridines
Authors: Bosch Joan , Bonjoch Josep , Serret Isabel 
Published: March 2009

AbstractThe intramolecular acylation of some δ‐keto acids derived from 3‐oxo‐2‐piperidinepropionic acid are described. Bicyclic enol lactones coming from an O‐acylation reaction are obtained in all cases. The regioselec‐tivity of these processes is discussed in terms of the acylating agent and the δ‐keto acid structure. The procedure establishes a convenient synthesis of hexahydro‐2‐oxopyrano[3,2‐b)pyridines.
Synthesis of 4‐alkyl‐4H‐benzo[e]‐ and 4H‐pyrido[2,3‐e]‐1,2,4‐triazin‐3‐one 1‐oxides for potential anticancer activity
Authors: Foye William O. , Kauffman Joel M. , Kim Young Ho 
Published: March 2009

AbstractAlkylation of the sodium salt of 4H‐benzo[e]‐1,2,4‐triazin‐3‐one 1‐oxide and its 7‐methyl homolog with benzyl bromide and chloromethoxyethyl acetate gave the 4‐substituted products. Alkylation with aceto‐bromoglucose formed the 3‐ether. Alkylation of 4H‐pyrido[2,3‐e]‐1,2,4‐triazin‐3‐one 1‐oxide gave the 4‐substi‐tuted products with both benzyl bromide and acetobromoglucose. Deacetylation of both the tetra‐O‐acetyl‐glucosyl and acetoxyethoxymethyl derivatives was accompolished was accompolished. Antileukemia tests for several of the 4‐alkyl derivatives showed no activity.
Pyridine N‐sulfides. Benzisothiazolo[2,3‐a]pyridinium tetrafluoroborates and benzothiopheno[3,2‐b]pyridines. Novel heterocyclic systems
Authors: Abramovitch Rudolph A. , Inbasekaran Muthiah N. , Miller Adrian L. , Hanna James M. 
Published: March 2009

Abstract2‐(2‐Mercaptophenyl)pyridines are prepared from the corresponding phenols and oxidized with N‐chloro‐succinimide and silver tetrafluoroborate to benzisothiazolo[2,3‐a]pyridine salts (4). The latter do not rearrange thermally or photochemically to benzothiopheno[3,2‐b)pyridines (19) and are attacked by nucleophiles at sulfur rather than in the pyridine ring, to give the original 2‐(2‐mercaptophenyl)pyridine back in a reaction involving a dismutation. 19 is prepared by rearranging O‐[2‐(3‐bromo‐2‐pyridyl)‐4‐nitrophenyl]dimethylthio‐carbamate to the S‐aryl compound and heating the latter with strong base.
Ring transformation of 6H‐cyclopropa[e]pyrazolo[1,5‐a]pyrimidine. IV (1). Reduction and reaction of 5a‐acetyl‐6a‐ethoxycarbonyl‐5a,6a‐dihydro‐6H‐cyclopropa[e]pyrazolo[1,5‐a]pyrimidine‐3‐carbonitriles with primary amines
Authors: Kurihara Takushi , Nasu Keiko , Tani Tsutomu 
Published: March 2009

AbstractThe reaction of 5a‐acetyl‐6‐ethoxycarbonyl‐5a,6a‐dihydro‐6H‐cyclopropa[e]pyrazolo[1,5‐a]pyrimidine‐3‐carbonitrile (1a) with benzylamine gave ethyl l‐benzyl‐5‐cyano‐8a,9‐dihydro‐2‐methyl‐1H‐pyrrolo[3,4‐e]‐pyrazolo[1,5‐a]pyrimidine‐8a‐carboxylate (2a), in addition to 5‐acetyl‐3‐benzylamino‐1‐(4‐cyanopyrazol‐3‐yl)‐ 2‐pyridone (3). Reaction of 1a with aniline gave ethyl 6‐acetyl‐8‐anilino‐3‐cyano‐7,8‐dihydro‐4H‐pyrazolo‐[1,5‐a][1,3]diazepine‐8‐carboxylate (4), in addition to ethyl 3‐cyano‐7‐methyl‐6‐pyrazolo[1,5‐a]pyrimidine‐acrylate (5). On the other hand, the same reactions of 1b with benzylamine or aniline gave 2b or 8b, respectively.Though catalytic hydrogenation of 1a over 5% palladium‐carbon proceeded by ring fission of cyclopropane ring to give 9, 1a (or 1b) afforded 4,5‐dihydro derivatives (13 or 15) by catalytic hydrogenation over platinum oxide.The reactivity of 5‐methoxy‐4,5,5a,6a‐tetrahydro‐6H‐cyclopropa[e]pyrazolo[1,5‐a]pyrimidine (16), which are related analogs of 1a,b, is also described.
Reactions of 3‐acetyltropolone and its methyl ethers with hydroxylamine. Formation of 8H‐cyclohept[d]isoxazol‐8‐one and 8H‐cyclohept[c]isoxazol‐8‐one
Authors: Sudoh Yasunori , Jin Zhong‐Tian , Imafuku Kimiaki , Matsumura Hisashi 
Published: March 2009

AbstractThe reaction of 3‐acetyltropolone (1) with hydroxylamine under the acidic condition gave 3‐methyl‐8H‐cyclohept[d]isoxazol‐8‐one (4) and its oxime (5), and under the neutral condition gave 4 and 3‐acetyltropolone oxime (6). The reaction of 3‐acetyl‐2‐methoxytropone (2a) with hydroxylamine under the acidic condition gave 4, 5, and 4‐methyl‐1H‐2,3‐benzoxazin‐1‐one (7), and under the neutral condition gave 4, 7, 3‐methyl‐8H‐cyclohept[c]isoxazol‐8‐one (8), and its oxime (9). The reaction of 7‐acetyl‐2‐methoxytropone (2b) with hydroxylamine under the acidic condition gave 4 and 5, and under the neutral condition gave 5, 7, and 9.
Studies on simplified ergoline derivatives. A general six‐step synthesis of phenyl‐substituted 4‐methyl‐3,4,4a,5,6,10b‐hexahydrobenzo[f]quinolin‐1‐(2H)‐one analogs
Authors: Salley John J. , Glennon Richard A. 
Published: March 2009

AbstractThis communication outlines the development of a novel, general synthetic route to substituted α‐tetralones 5, their subsequent conversion to the α,β‐unsaturated ketones 11, and an improved, one‐step transformation of 11 to the tricyclic title compounds 1. Thus, substituted derivatives of 1 can be prepared in six steps from simple benzaldehydes, or, in three steps from more readily available α‐tetralones.
The synthesis of chiral dimethyl substituted macrocyclic polyether‐diester ligands
Authors: Jones Brian A. , Bradshaw Jerald S. , Izatt Reed M. 
Published: March 2009

AbstractA new series of chiral macrocyclic polyether‐diester ligands has been prepared from four chiral dimethyl substituted tetraethylene glycols (15a,b,16,17) and 2,6‐pyridinedicarbonyl chloride (products 5a‐7), diglycolyl chloride (products 8–10), thiadiglycolyl chloride (product 11), 2,5‐furandicarbonyl chloride (product 12), 4‐chloro‐2,6‐pyridinedicarbonyl chloride (product 13), and 4‐methoxy‐2,6‐pyridinedicarbonyl chloride (product 14). The chiral dimethyl substituted tetraethylene glycols (15a‐17) were prepared from ethyl (S)‐lactate.
Synthesis of imidazole derivatives with potential biological activity
Authors: Belgodere E. , Bossio R. , Parrini V. , Pepino R. 
Published: March 2009

Abstractl‐Alkylaryl‐2‐sulfamoylimidazole‐5‐carboxamides IV, V and VI were prepared starting from methyl l‐alkyl‐aryl‐2‐mercaptoimidazole‐5‐carboxylates I, II and III. Many interesting reaction intermediates such as the l‐alkylaryl‐2‐sulfamoylimidazole‐5‐carboxylic acids (XVII, XX and XXI) were isolated. The structures of all of the compounds were determined by ir and nmr spectroscopy. Diuretic acitivity tests were also carried out on these compounds. In addition, l‐alkylarylimidazole‐5‐carboxamides XXVII, XXVIII and XXIX were also prepared and tested for biological activity.
Potential anticonvulsants. V. The condensation of isatins with C‐acetyl heterocyclic compounds
Authors: Popp F. D. 
Published: March 2009

AbstractA number of C‐acetyl heterocyclic compounds were condensed with isatin and substituted isatins to give a series of 3‐hydroxy‐3‐substituted oxindoles. The products from 2‐acetylfuran and isatin, 2‐acetylthiophene and isatin, and 2‐acetylpyridine and 1‐methylisatin were active at 100 mg/Kg in the maximal electroshock seizure test.
Preparation of compounds in the new dipyrrolo[3,4‐b:3′,4′‐e]‐pyridine series from 1‐benzylidene‐2,3‐dioxopyrrolidines. A variation of the hantzsch synthesis
Authors: Snyder Carroll A. , Thorn Mark A. , Klijanowicz James E. , Southwick Philip L. 
Published: March 2009

AbstractTreatment of easily prepared l‐substituted‐4‐benzylidene‐2,3‐dioxopyrrolidines with ammonium formate produces 1,2,4,6,7,8‐hexahydro‐2,6‐disubstituted‐8‐aryldipyrrolo [3,4‐b:3′,4′‐e]pyridine‐3,5‐diones (II), usually in yields of 50 to 60%. Aromatization of the dihydropyridine ring of the hexahydroderivatives II yields corresponding 1,2,6,7‐tetrahydro‐2,6‐disubstituted‐8‐aryldipyrrolo[3,4‐b:3′,4′‐e]pyridine‐3,5‐diones (III). These compounds appear to be the first to incorporate the dipyrrolo[3,4‐b:3′,4′‐e]pyridine ring system.
Influence de la structure sur l'hydrolyse des N‐pyrrolylmethylene‐2 anilines
Authors: Ali‐Bey Aǐcha , Loukil Hasna Fatiha , Gosselin Gilles , Mathieu André , Mesli Abderrezzak 
Published: March 2009

AbstractL'hydrolyse de la fonction imine d'une famille de bases de Schiff, dérivees du pyrrole aldéhyde‐2 et d'anilines substitutées (X = H, p‐OCH3, p‐OC2H5, p‐CH3, p‐Cl, p‐Br, m‐CN, m‐NO2, p‐NO2), est étudiee dans tout le domaine de pH. Les courbes d'hydrolyse log kobs (mn−1) = f (pH) sont établies, en milieu hydro‐méthanolique tamponné, par polarographie ou ampéiometrie. L'allure des courbes obtenues aux pH > 5 in‐dique que les N‐pyrrolylméthylène‐2 anilines s'hydrotysent selon le mécanisme setenu pour les N‐benzyli‐denes anilines. La stabilité particuliere des produits étudies aux pH < 5 a permis d'obtenir des courbes d'hydrolyse completes en milieu acide. Une excellente corrélation de Hammett (ϱp′ = + 1,73) a pu ětre ainsi établie sur les paliers ou maximums qui apparaissent aux fortes acidités. Cette stabilité est interprétee en considérant l'effet électrodonneur spécifique du noyau pyrrole. L'influence du paramètre structural X sur la morphologie des courbes log kobs = f (pH) et sur le mecanisme de l'hydrolyse de la fonction imine a pu ětre discutée dans tout le domaine de pH.
Synthesis and demethylation of new 5,6,7,8‐tetrahydro‐4,9‐dimethoxy‐1H‐benz[f]indole
Authors: Malesani Giorgio , Ferlin Maria Grazia , Masiero Sergio 
Published: March 2009

AbstractThe title compound 17 was prepared in good yield starting from 5,6,7,8‐tetrahydro‐l‐naphthol (9) by an advantageous synthesis route consisting of eight steps, as indicated in Scheme 2. Demethylation by reflux heating with anhydrous aluminium chloride in dry benzene furnished 4,9‐dihydroxy‐ and 4,9‐dioxo‐5,6,7,8‐tetrahydro‐1H‐benz[f]indoles (compounds 18 and 19, respectively). All new products were identified on the basis of spectral and analytical data.
Studies on the synthesis of heterocyclic compounds. VIII. Action of acyl halides on 2,2‐di‐n‐butyl‐1,3,2‐benzoxathiastannole, 2‐chloro‐1,3,2‐benzoxathiaarsole and ‐stibole
Authors: Anchisi Carlo , Corda Luciana , Fadda Anna , Maccioni Antonio , Podda Gianni 
Published: March 2009

AbstractThe cleavage reaction of some 1,3,2‐benzoxathiastannole, ‐arsole and ‐stibole derivatives with acetyl and benzoyl chloride is described. The reactions were carried out refluxing in benzene or at room temperature. In all cases, the reaction occurs through the initial cleavage of the S‐M linkage with formation of the respective o‐acylthio derivatives. The structure of the prepared compounds was assigned on the basis of their analytical, physical and spectral data.
On the amination of 1,2,4‐triazines by potassium amide in liquid ammonia and by phenyl phosphorodiamidate. A 15n‐study
Authors: Rykowski A. , Van Der Plas H. C. 
Published: March 2009

AbstractThe amination of 5‐R‐ and 6‐R‐3‐X‐1,2,4‐triazines (R = C6H5, t‐C4H9, X = SCH3, SO2CH3, N+ (CH3)3, Cl) by potassium amide in liquid ammonia has been studied. In all reactions the formation of the corresponding 3‐amino‐1,2,4‐triazines takes place; in some reactions by‐products were found: from 5‐phenyl‐ and 5‐t‐butyl‐3‐(methylthio)‐1,2,4‐triazine a ring contracted product i.e. 5‐phenyl and 5‐t‐butyl‐3‐(methylthio)‐1,2,4‐triazole, from 6‐phenyl‐3‐(methylthio)‐1,2,4‐triazine the dimer 3,3′‐bis‐(methylthio)‐6,6′‐bisphenyl‐5,5′‐bi‐1,2,4‐triazine and from 5‐t‐butyl‐3‐(trimethylammonio)‐1,2,4‐triazine chloride compound bis‐(5‐t‐butyl‐1,2,4‐triazin‐3‐yl)‐ amine. Furthermore the conversion of 5‐phenyl‐ and 5‐t‐butyl‐1,2,4‐triazin‐3‐one into the corresponding 3‐amino compound by treatment with phenyl phosphorodiamidate (PPDA) was studied. A 15N study of these aminations showed that nearly all compounds undergo substitution according to both SN(AE) and SN(ANRORC) processes. The contribution of each of the competitive mechanisms to the amination is strongly influenced by the character of the leaving group.
Preparation of 1‐hydroxyethyl‐2‐trideuteriomethyl‐5‐nitroimidazole
Authors: Miyano Masateru , Smith Jeffrey N. 
Published: March 2009

AbstractThe title compound was prepared by two different procedures. The first route starts with acetonitrile‐d3 and goes through 2‐trideuteriomethyl‐5‐nitroimidazole (6) (Scheme I). The second and more convenient process is direct labeling of metronidazole (1) with alkaline ethanol‐d1.
The synthesis of 8‐azidoadenine, a photoaffinity labeling agent
Authors: Marburg S. , Jorn D. , Tolman R. L. 
Published: March 2009

AbstractThe photoaffinity labeling agent, 8‐azidoadenine, was prepared in good yield by hydrolytic cleavage of 8‐azidoadenosine and characterized as a homogeneous compound. Previously reported physical data for this compound was shown to be in accord with mixtures of 8‐azido‐ and 8‐bromoadenine.
1‐Phenyl‐6,7‐disubstituted‐aminopropyl)‐1,2,3,4‐tetrahydroisoquinolines as possible antituberculer agents
Authors: Kumar P. , Dhawan K. N. , Kishor K. , Bhargava K. P. , Satsangi R. K. 
Published: March 2009

AbstractThe Condensation of 3,4‐disubstituted phenylethylamine and benzaldehyde furnished l‐phenyl‐6,7‐disubstituted‐1,2,3,4‐tetrahydroisoquinolines l. which on reaction with 1,3‐dibromopropane gave l‐phenyl‐6,7‐disubstituted‐2‐(3‐bromoprophyl)‐1,2,3,4‐tetrahydroisoquinolines 2. The reaction of 2 with different secondary amines resulted in the synthesis of 3. The compounds 3 were screened for their in vitro antituberculer activity against Mycobacterium smegmatis, and some of them have been found to be total inhibitors of M. Smegmatis
The synthesis of a potential bisintercalating ethidium bromide analog
Authors: Lopp Irene G. , Wilson W. David , Boykin David W. 
Published: March 2009

AbstractThe synthesis of diethyl‐1,3,4,13b‐tetrahydro‐13b‐phenyl‐2H‐pyrimido[1,2‐f]phenanthridine‐7,12‐dicarba‐mate and N,N′‐3,3′[5,5′‐Bis(3,8‐biscarbethoxyamino‐6‐phenyl)phenanthridinium]propylglutarylamide dichloride are reported starting from 3,8‐biscarbethoxyamino‐5‐(3′‐bromopropyl)‐6‐phenylphenanthridinium bromide.
Bromothiophene reactions. II. A novel rearrangement in the zinc and acetic acid reduction
Authors: Alvarez‐Insúa A. S. , Conde S. , Corral C. 
Published: March 2009

AbstractThe elimination of the α‐bromine atoms of the bromothienylethanolamine derivatives 2a,b,c,d with zinc and acetic acid unexpectedly involved a migration of the ethanolamine side chain from the 3 to the 2 position in the thiophene ring. Experiments carried out with simpler analogous compounds 3, 4 and 6 seem to indicate that this rearrangement takes place only in those cases in which the carbon atom of the side chain next to the ring supports an oxygen atom capable of being protonated in the reaction medium. A tentative mechanism is proposed to explain the experimental results.
Sur l'orientation de la nitration des dérivés Bz‐méthoxylés de l'acétyl‐2 benzofuranne
Authors: Bachelet Jean‐Pierre , Clavel Jean‐Marc , Demerseman Pierre , Royer René 
Published: March 2009

AbstractLes nitrations directes des acétyl‐2 Bz‐méthoxy benzofurannes par l'acide nitrique dans l'anhydride acétique donnent toujours deux dérivés nitrés sur l'homocycle en ortho ou, éventuellement, en para du méthoxyle, en proportions différentes selon les cas. Les éthers obtenus sont aisément déméthylables par le chlorure de pyridinium. On forme ainsi, en particulier, un analogue nitré de l'Euparone.
Synthesis of thiazolotriazepinones
Authors: Peet Norton P. , Sunder Shyam , Barbuch Robert J. 
Published: March 2009

AbstractThe synthesis of 4,5‐dihydro‐7‐phenylthiazolo[2,3‐c][1,2,4]triazepin‐3(2H)‐one (4) from 2‐propenoic acid 2‐(4‐phenyl‐2‐thiazolyl)hydrazide (14), is reported. A synthesis of 4 which was reported earlier by Mahajan, Sondhi and Ralhan (9), from 3‐chloropropanoic acid 2‐(4‐phenyl‐2‐thiazolyl)hydrazide (3), is erroneous. We were able to cyclize 3 to 1‐(4‐phenyl‐2‐thiazolyl)‐3‐pyrazolidinone (5). The cyclizations of 14 to 4 and 3 to 5 are consistent with the Baldwin Rules for Ring Closure.
Reactions of halogenoquinolizinium bromides with diethylamine
Authors: Sanders Georgine M. , van Dijk M. , van der Plas H. C. 
Published: March 2009

AbstractThe reactions of quinolizinium bromide (QB) and its four monobromo derivatives with diethylamine have been investigated. For Br in position 2 or 4, substitution is the main process, whereas for Br in positions 1 and 3 quantitative ring opening is found. The substituted pyridylbutadienes formed by ring opening, are cis‐trans‐butadienes, which isomerize into the all‐trans forms. The steric cours of the ring opening is explained.
Tetracyclic phenothiazines. VII. Electron impact promoted mass spectral fragmentation of some pyrido[3,2,1‐kl]phenothiazines
Authors: Vishwakarma L. C. , Martin A. R. 
Published: March 2009

AbstractThe mass spectral fragmentation pattern of a series of pyrido[3,2,1‐kl]phenothiazines is reported. The major fragments are derived from the breakdown of the pyrido ring and substituents thereon. The 1,2‐/2,3‐unsaturated, unsubstituted and most of the 3‐substituted compounds show the molecular ion as the base peak indicative of their relative stability toward electron impact. The genesis of the base peaks from the molecular ions of the 2,2‐dithiophenyl substituted compounds probably involves a concerted expulsion of a neutral diphenyldisulfide molecule and hydrogen atom transfer from the 1‐position to the 2‐position in the pyrido ring. On the other hand, 2‐thiophenyl substituted molecular ions lead to base peaks involving simultaneous ring opening of the pyrido ring, cleavage of phenylthiomethylene moiety as a radical and contractive ring closure to the pyrrole system. These two mechanisms appear to be diagnostic for distinguishing 2,3‐ versus 2,2‐positional isomers. The McLafferty rearrangement takes place in the 2‐thiophenyl and 2,2‐dithiophenyl substituted compounds. The retro‐Diels‐Alder fragmentation of the pyrido ring occurs in varying degrees depending on the nature of the 2‐ and 3‐ substituents and also the presence or absence of unsaturation in the pyrido ring. In the 2‐thiophenyl‐3‐keto compounds, thiophenyl group participation with 3‐carbonyl carbon and oxygen atoms is observed in the genesis of some interesting ion fragments. The detection of metastable ions in the spectra of 1,2‐dihydro‐2‐thiophenyl‐, 1,2‐dihydro‐2,2‐dithiophenyl‐3‐hydroxy‐, and 1,2‐dihydro‐2,2‐dithiophenyl‐3‐keto‐3H‐pyrido[3,2,1‐kl]phenothiazines; and spectra of 1,2‐dihydro‐3‐methyl‐, 1,2‐dihydro‐2‐carbethoxy‐3‐keto‐ and 1,2‐dihydro‐2‐thiophenyl‐3‐keto‐3H‐pyrido[3,2,1‐kl]pheno‐thiazines at low voltage support major fragmentation pathways.