bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quinoline syntheses by reaction of hydrazoic acid with α,β‐disubstituted cis‐chalcones
Authors: Pratt Robert E. , Welstead William J. , Lutz Robert E. 
Published: March 2009

AbstractHydrazoic‐sulfuric acid mixture converted cis‐α‐phenyl‐β‐benzoylchalcone (trans‐dibenzoylstilbene, 4) into 2,3‐diphenyl‐4‐benzoylquinoline (5) the structure of which was proved by debenzoylation to 2,3‐diphenylquinoline. α,β‐Diphenyl and cis‐α,β‐dibromochalcones similarly were converted respectively into 2,3,4‐triphenylquinoline (19) and 2‐phenyl‐3,4‐dibromoquinoline (20). The structure of 19 was shown by difference from the corresponding isoquinoline 21 (synthesized). Smith's mechanism for the analogous conversion of o‐phenylbenzophenone into 9‐phenylphenanthridine through the 9‐fluorenol and the 9‐hydroazide with loss of nitrogen and ring expansion, was supported by methyl label experiments using 2‐(p‐tolyl)benzophenone which gave a 53:47 mixture of 3‐ and 8‐methyl‐6‐phenylphenanthridines. Applicability of the mechanism to the reactions with disubstituted cis‐chalcones was shown by sulfuric acid conversions of two of these into indenol 22 and 2‐bromo‐3‐phenylindenone (24), respectively. trans‐Dibenzoylstilbene underwent resinification in sulfuric acid, giving the quinoline (5) only when hydrazoic acid was present.
Synthesis of 4‐hydroxy‐2‐methylisocarbostyril‐3‐carboxanilides
Authors: Lombardino Joseph G. 
Published: March 2009

AbstractA procedure for preparing the title compounds is reported. These compounds represent the first 2‐substituted‐4‐hydroxyisocarbostyrils, a structural type which could not be obtained by N‐alkylation of the previously known 2H‐4‐hydroxyisocarbostyril. Although 3‐carboxanilides in this series could not be made by aminolysis of the corresponding 3‐ester, they were successfully prepared from 4‐hydroxy‐2‐methylisocarbostyril using aryl isocyanates and sodium hydride in hexamethylphosphoramide as solvent. Evidence is presented for an enolic (“4‐hydroxy”) form of the title compounds and preference for O‐alkylation was observed. Contrary to previous reports, data was obtained to support the enolic structure of the previously known 4‐hydroxyisocarbostyril.
The reactions of 4‐dicyanomethylene‐2‐phenyl‐4H‐1‐benzopyran and some benzologs with nucleophiles
Authors: Reynolds G. A. , Vanallan J. A. , Petropoulos C. C. 
Published: March 2009

Abstract4‐Dicyanomethylene‐2‐phenyl‐4H‐1‐benzopyran (1) reacts with primary amines under mild conditions to give 4‐imino‐3‐alkyl‐5‐alkylimino‐2‐phenyl‐3,4‐dihydro‐5H‐[1]benzopyrano[3,4‐c]‐pyridine derivatives which, in turn, are hydrolyzed with acid to 4‐imino‐3‐alkyl‐2‐phenyl‐3,4‐dihydro‐5H‐[1]benzopyrano[3,4‐c]pyridin‐5‐ones. When more vigorous conditions are employed for the reactions of 1 with primary amines, Dimroth rearrangements take place and the products are derivatives of 4‐alkyl‐ (or aryl)amino‐5‐alkyl‐ (or aryl)imino‐2‐phenyl‐5H‐[1]benzopyrano‐[3,4‐c]pyridine. The latter compounds are hydrolyzed by acid to the corresponding 5‐pyridone derivatives. The reaction of 1 with piperidine gives 2‐phenyl‐4‐piperidyl‐5H‐[1]benzopyrano‐[3,4‐c]pyridin‐5‐one. Sodium methoxide reacts with 1 to give 3‐cyano‐2‐methoxy‐4‐(2‐hydroxyphenyl)‐6‐phenylpyridine. Two benzologs of 1 have been allowed to react with primary and secondary amines and the products are analogous to those obtained from 1.
Synthesis of 3,5‐Disubstituted‐4,5‐dihydroindeno[1,2‐c] [1,2]diazepin‐6(1H)‐ones
Authors: Mosher William A. , Innes John E. 
Published: March 2009

Abstract3,5‐Disubstituted 4,5‐dihydroindeno[1,2‐c][1,2]diazepin‐6 (1H)‐ones (3a–g) were obtained in 29–72% yields by condensing 2‐(substituted‐2‐acylethyl)‐1,3‐indandiones (1a–n) with hydrazine. The NH group of the indenodiazepinones 3a–g is quite unreactive. Two methods based on the Michael reaction were used for preparing the acylethylindandiones 1a–n: one from 1,3‐indandione and chalcone‐type compounds and the other from 2‐benzylidene‐1,3‐indandione and acetophenones. The latter method was found more practical and of more general application.
Cyanorhodanines
Authors: Allan Frederick J. , Allan G. Graham 
Published: March 2009

AbstractThree types of cyanorhodanines have been synthesized for evaluation as fungicides for the protection of cellulose. The first group comprised five cyanobenzylidenerhodanines prepared by the condensation of 4‐cyanobenzaldehyde with rhodanine and its 3‐allyl, ‐carboxymethyl, ‐ethyl and ‐phenyl congeners. The corresponding carboxy analogs were similarly synthesized from terephthaldehydic acid. The second group consisted of cyanobenzylidenerhodanines containing a β‐cyanovinyl aromatic side‐chain introduced by the condensation of ethyl cyanoacetate with formylbenzylidenerhodanines. The latter are versatile intermediates for the synthesis of substituted rhodanines and a convenient procedure for their preparation is now reported. The third type of cyanorhodanines contained a β,β‐dicyanovinyl aromatic side‐chain correspondingly prepared from the formylbenzylidenerhodanines by condensation with malononitrile.
Bis‐Pyrazolones as azodienophiles
Authors: Gillis Bernard T. , Valentour James C. 
Published: March 2009

AbstractLead tetraacetate oxidations of 2,3,3a,4,6,7,7a,8‐octahydrobenzo[1,2‐c:4,5‐c']dipyrazolo‐3,7‐dione and 2,3,3a,4,5,5a,6,7‐octahydrobenzo[2,1‐c:3,4‐c']dipyrazolo‐3,6‐dione in the presence of 1,3‐cyclopentadiene, 1,3‐cyclohexadiene, 2,3‐dimethyl‐1,3‐butadiene or 1,4‐diphenyl‐1,3‐butadiene have yielded octahydrodipyridazino[1,2‐a:1,2‐a']benzo[1,2‐c:4,5‐c']dipyrazolo‐6,14‐diones and octahydrodipyridazino[1,2‐a:1,2‐a']benzo[2,1‐c:3,4‐c']dipyrazolo‐6,9‐diones. In one of the eight Diels‐Alder reactions two isomeric products were isolated.
The synthesis of 3,4,4a,9a‐tetrahydro‐2(1H)‐carbazolones
Authors: Wittekind Raymond R. , Lazarus Sam 
Published: March 2009

AbstractCyclization of 4‐(1‐methylindol‐3‐yl)‐2‐butanone and the corresponding 1‐benzyl analog in trifluoroacetic acid furnishes 9‐methyl‐ and 9‐benzyl‐3,4,4a,9a‐tetrahydro‐2(1H)‐carbazolone, respectively. Under the same conditions, 4‐(indol‐3‐yl)‐2‐butanone gives the dimer, 3‐(3‐oxo‐butyl)‐2‐[3‐(3‐oxobutyl)‐2‐indolinyl] indole. When boron trifluoride etherate is used instead of trifluoroacetic acid, the desired 3,4,4a,9a‐tetrahydro‐2(1H)‐carbazolone is obtained. The determination of the structure of the tetrahydrocarbazolones is described and the stereochemistry of the ring fusion is discussed.
Nitrene insertion reactions. 1. Dimethyl N‐carbethoxyazepines and their cycloaddition reaction products
Authors: Photis James M. 
Published: March 2009

AbstractDimethyl‐N‐carbethoxyazepines, isolated from the reaction between ethyl azidoformate and o‐, m‐ and p‐xylenes, react with tetracyanoethylene to give [4 + 2] Diels‐Alder adducts. Nitroso‐benzene is inert toward 2‐methylazepines, but reacts with 3,6‐dimethyl‐N‐carbethoxyazepine to give a [6 + 2] cycloadduct. The effect of two methyl substituents on the course of the cycloaddition reactions is discussed.
Synthesis of heterocyclic compounds. II. A simple one‐step synthesis of pyridines from aldehydes and malononitrile
Authors: Alvarez‐Insúa Alberto S. , Lora‐Tamayo M. , Soto José L. 
Published: March 2009

AbstractThe condensation of several aldehydes with malononitrile in the presence of a alcohol‐alkoxide system provides a new simple, one‐step route to 4‐substituted 2‐amino‐3,5‐dieyano‐6‐alkoxy‐pyridines. The best results are obtained with the aromatic aldehydes. The structure of these compounds was established from a study of their infrared, ultraviolet and nuclear magnetic resonance spectra.
Reaction of phenolic mannich bases with enamines. General synthesis of pyran‐containing fused ring systems
Authors: Von Strandtmann Maximilian , Cohen Marvin P. , Shavel John 
Published: March 2009

AbstractThe reaction of o‐phenolic Mannich bases with enamines yields cyclic O,N‐acetals having a 2‐aminodihydropyran or a spiropyranopiperidine structure in common. The 2‐aminodihydro‐pyrans are easily converted to 2‐hydroxydihydropyrans and to pyrans. The preparation of a large variety of pyran‐containing fused ring systems is reported.
Thiophene series. Substituent effect on thiophenoxy debromination of various 2‐nitro‐3‐bromo‐5‐X‐thiophenes
Authors: Guanti Giuseppe , Dell'Erba Carlo , Spinelli Domenico 
Published: March 2009

AbstractThe kinetics of the reaction of a series of 2‐nitro‐3‐bromo‐5‐X‐thiophenes with sodium thiophenoxide in methanol were determined.The plot of log k against σ‐values gave ρ‐value + 4.51 at 20°.Good correlation was observed pointing out the validity of the Hammett relationship for reactions occurring directly on the thiophene ring at the β‐position with respect to the heteroatom.
Rearrangements of the aminoalkylation products of tetrahydro‐2H‐1,3‐oxazine‐2‐thione
Authors: Clapp Richard C. , Long Louis 
Published: March 2009

AbstractThe nature of the compounds afforded by the rearrangement of the aminopropylation and aminoethylation products of tetrahydro‐2H‐1,3‐oxazine‐2‐thione (I) has been investigated. In both instances compounds that can be considered to result from ring opening at either the C‐O or C‐S bond of a hypothetical bicyclic intermediate of structure IV were obtained. The compounds required for identification of the rearrangement products have been prepared by the reaction of the 2‐methylthio derivatives of 2‐thiazoline, 5,6‐dihydro‐4H‐1,3‐thiazine, and 5,6‐dihydro‐4H‐1,3‐oxazine with the appropriate hydroxyalkylamine or mercaptoalkylamine.
Benzothiazolium derivatives. III. Nucleophilic substitution reactions of benzothiazolium salts
Authors: Sohar Paul , Denny George H. , Babson Robert D. 
Published: March 2009

AbstractThe reactions of 2,3‐dihydrothiazolo[2,3‐b]benzothiazolium bromide 1 (A− Br−) with certain nucleophilic reagents have been performed for the purpose of ascertaining the reaction pathways and identifying the group that is displaced from the central carbon atom of the dithiocarbamate system. The nature of complex salt‐like intermediates formed initially from 1 (A− Br−) has been studied and confirmed. For comparison, a number of nucleophilic substitution reactions of 2‐methylthio‐3‐methylbenzothiazolium iodide 17 and 2‐dimethylamino‐3‐methylbenzothiazolium perchlorate 18 have been examined.
Luminescent 2‐(hydroxyaryl)‐1 H‐naphth[2,3‐d] imidazole derivatives
Authors: Orlando C. M. , Wirth J. G. , Heath D. R. 
Published: March 2009

AbstractThe synthesis and spectroscopic properties of a new class of luminescent 1H‐naphth[2,3‐d]‐imidazole compounds are described. The ultraviolet spectra of 2‐(hydroxyaryl)‐1H‐naphth[2,3‐d]‐imidazole derivatives are presented and discussed. Significant effects of structure and physical state of the luminescent compounds are observed on the measured emission wave length throughout the visible spectrum. The luminescence quantum efficiency of one of the naphthimidazole derivatives is reported.
Pyridazines. XXXVIII. Pyrrolo[1,2‐b] pyridazines and 4H‐4a,7b‐diazacyclopent[cd] indenes
Authors: Zupan M. , Stanovnik B. , Tišler M. 
Published: March 2009

AbstractPyrrolo[1,2‐b] pyridazines have been prepared and investigated for electrophilic substitutions. Depending on the electrophile and reaction conditions, mono, di, tri or tetrasubstituted derivatives were formed. Some investigations are reported also for the related 4H‐4a,7b‐diazacyclopent[cd]‐indenes.
Azinotriazines. I. Synthesis and spectral data of pyrido[3,2‐e] ‐as‐triazines
Authors: Lewis Arthur , Shepherd Robert G. 
Published: March 2009

AbstractA series of pyrido[3,2‐e]‐as‐triazines (VI) was prepared via acid‐catalyzed cyclization of suitable 2‐substituted 3‐aminopyridines obtained by reduction of the corresponding 3‐nitro‐pyridines. Cyclization of 3‐amino‐2‐hydrazinopyridines (III) with triethyl orthoformate and hydrochloric acid, or cyclodehydration of 2‐(2‐acetylhydrazino)‐3‐aminopyridines (IV) with alcoholic hydrogen chloride gave 1,2‐dihydropyrido[3,2‐e]‐as‐triazine hydrochloride (V). Mild dehydrogenation with alkaline potassium ferricyanide yielded heteroaromatic pyrido[3,2‐e]‐as‐triazines (VI), for which ultraviolet and nmr spectral data are reported.
Azinotriazines. II Cyclizations leading to pyrido[3,4‐e] ‐ and [4,3‐e]‐as‐triazines. Ring interconversion of a pyrido‐as‐triazine 1‐oxide to a pyridotriazole
Authors: Lewis Arthur , Shepherd Robert G. 
Published: March 2009

AbstractTreatment of 4‐chloro‐3‐nitropyridine (I) with hydrazine hydrate followed by catalytic reduction gave 3‐amino‐4‐hydrazinopyridine (III). Acid‐catalyzed cyclizations of III and subsequent dehydrogenation gave pyrido[3,4‐e]‐as‐triazines (V). Treatment of I with guanidine followed by base‐catalyzed cyclization gave 3‐aminopyrido[4,3‐e]‐as‐triazine 1‐oxide (VII). The 1‐oxide function was removed by reduction and subsequent dehydrogenation gave the 3‐amino derivative (IX). On treatment with hot alkali VII rearranged to a triazolo[4,5‐c]pyridine (X). The ultraviolet and nmr spectra of derivatives of the title ring systems are reported.
Nitro derivatives of phenyl‐1,2,3‐triazole
Authors: Neuman Peter N. 
Published: March 2009

AbstractA number of tri‐ and tetranitro‐N‐phenyl‐1,2,3‐triazolyl compounds were synthesized by a combination of condensation, cycloaddition, and nitration reactions, and their crystal densities, impact sensitivities, and thermal stabilities were determined.
Sur la synthèse des furo[3,2‐c] pyridines
Authors: Eloy F. , Deryckere A. 
Published: March 2009

AbstractLe principe de la cyclisation des isocyanates de vinyle, substitués par un groupement vinylidène appartenant à un hétérocycle, a été appliqué à la synthèse de furo[3,2‐c] pyridines. La cyclisation thermique de furyl‐2 isocyanato‐1 éthylénes a conduit à des furo[3,2‐c]pyridones qui furent utilisées comme intermédiates pour l'obtention d'autres dérivés furopyridiniques.
Derivatives of 10,11‐dihydro‐5H‐dibenzo[a,d] cycloheptene and related compounds. III. Azaketones
Authors: Villani Frank J. , Daniels Peter J. L. , Ellis Claire A. , Mann Thomas A. , Wang Kai‐Chih 
Published: March 2009

AbstractThe preparation and properties of four isomeric azadibenzoeycloheptenones 3 and their 10,11‐dihydro derivatives 2 are described. The ketones 2 were prepared by cyclization of appropriately substituted phenethylpyridine carboxylic acids and dehydrogenated to 3. Four monochloro derivatives 24 of the 4‐azaketone 2d are also described.
Hydrogen bonded complexes of ϵ‐caprolactam
Authors: Wigler Paul W. , Vercellotti Sharon V. 
Published: March 2009

AbstractThe ultraviolet absorption band of a complex between 9‐ethyladenine and ∈‐caprolactam has been observed at a wavelength longer than that of the absorption band for the 9‐ethyladenine monomer. Absorbance values (at 277.5 mμ) of solutions that contained 9‐ethyladenine and different concentrations of ∈‐caprolactam in cyclohexane were determined at different temperatures. Linear plots were utilized to determine the apparent association constant (K′ ) of the 9‐ethyladenine‐caprolactam complex over the range of 25° to 60°. The K′ values for the complex of 4‐aminopyrimidine and ∈‐caprolactam were determined for the same temperature range from the absorbance of cyclohexane solutions at 282.5 mμ. The K' values of the two complexes are the same at 25°, but ∈‐caprolactam is more strongly bonded to 9‐ethyladenine than to 4‐aminopyrimidine at elevated temperatures. The synthesis of 4‐amino‐1‐ethylbenzimidazole hydro‐chloride was performed. An attempt to detect a complex between ∈‐caprolactam and 4‐amino‐1‐ethylbenzimidazole in a cyclohexane solution was not successful.
An unusual arylation of 4‐oxo‐3,4‐dihydropyrimido[4,5‐b]quinoline
Authors: Campaigne E. , Randau G. 
Published: March 2009

AbstractTreatment of 4‐oxo‐3,4‐dihydropyrimido[4,5‐6 ]quinoline (II) with phosphorus oxychloride and a dialkylaniline resulted in the introduction of a p‐dialkylaminophenyl group at position‐5, and reduction of the central (pyridine) ring, as well as substitution of oxygen by chlorine at po‐sition‐4, forming compounds considered to be 4‐chloro‐5‐(p‐dialkylaminophenyl)‐5, 10‐dihydro‐pyrimido[4,5‐6 ]quinolines (XV). Several 4‐oxo‐3,4‐dihydropyrimido[4,5‐b ]quinolines having phenyl substituents at position‐5 were synthesized unequivocally, and could be readily reduced to the corresponding 4‐oxo‐5‐phenyl‐3,4,5,10‐tetrahydropyrimido[4,5‐6]quinolines, and the 4‐oxo group replaced by chlorine, in the usual manner, leading to compounds related structurally to XV. Comparison of the chemical and physical properties of these compounds established the structure of XV, and a mechanism which rationalizes the formation of XV from II is presented.
The synthesis of oxazolo‐ and oxazino[3,2‐d] [1,4]benzodiazepinones
Authors: Lemke Thomas L. , Hanze Arthur R. 
Published: March 2009

AbstractCyclization of 2′‐benzoyl‐4′‐chloro‐2‐[(2‐hydroxypropyl)amino]acetanilide (8) and 2′‐bcnzoyl‐4‐ehloro‐2‐[(3‐hydroxypropyl)amino]acetanilide (7) led to the respective oxazolo (3) and oxazino (5) analogs of 7‐chloro‐1,3‐dihydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐one. Cyclization of 2′‐benzoyl‐4′‐chloro‐2‐[2,3‐dihydroxypropyl)amino]acetanilide (9) could produce either the oxazolo (4) or oxazino (10) analog. Data is presented to show that cyclization occurred to give the oxazolo (4) analog.
Novel buron heterocycles. I. 2,3‐dihydro‐1,3,2‐benzodiazaborin‐4(III)‐ones and 1,2‐dihydro‐ 1,3,2‐benzodiazaborines
Authors: Yale Harry L. 
Published: March 2009

AbstractA series of 2,3‐dihydro‐1,3,2‐benzodiazaborin‐4(IH)‐ones have been prepared and their ir spectra compared with those of their carbon isosteres. Solvolysis of these boron compounds in ethanol has been followed by uv and reveals a relationship between structure and rates of ethanol‐ysis. Unexpectedly, these boron heterocycles, in contrast to their carbon isosteres, dissolve in aqueous alkali to form stable anions and the significance of this is discussed. The 1 :1 adducts of 1 and phosphorus oxychloride has been utilized to prepare two derivatives of the very stable 1,2‐dihydro‐2‐phenyl‐1,3,2‐benzodiazaborin heterocycle.
Investigation of routes to indeno[2,1‐f] ‐2H‐1,2,4‐triazepinediones
Authors: Mosher William A. , Foothill Richard H. 
Published: March 2009

AbstractThe synthesis of a number of 3‐(substituted thiosemiearbazido)‐2‐(a]koxycarbonyl)indones (1) from 2‐alkoxycarbonyl‐1, 3‐indandiones and substituted thiosemicarbazides is described. Cyeliza‐tion of compounds 1 in the presence of a variety of catalysts gave substituted Δ2‐1,2,4‐triazoline‐5‐thiones (3) and (4), instead of the expected substituted 3(4H)‐thioxoindeno[2,1‐f]‐2H‐1,2,4‐triazepine‐5(5aH),6‐diones (2). The preparation of 4‐(2‐methyl‐1,3‐dioxo‐2‐indanylmethyl)semi‐carbazide (9) is reported. Cyelization of 9 gave 5,5a‐dihydro‐5a‐methylindeno[2,1‐f]‐2H‐1,2,4‐triazepine‐3(4H),6‐dione (10). Structure assignments of these compounds are discussed.
Small charged rings. XIV. Dimer formation through 2‐arylaziridinium salts
Authors: Leonard Nelson J. , Klainer Jeremy A. 
Published: March 2009

Abstract2,5‐Diary 1‐substituted N,N,.N',N' ‐lelramethylpiperazinium diperchlorates have been synthesized in two steps: condensation of an aromatic aldehyde with dimethylamine perchlorate to give the corresponding N,N‐dimelhylaralkylideneiminium perehlorate, followed by reaction with diazo‐methane. Nmr evidence was obtained for the intermediate in the second step being the corresponding 2‐aryl‐1, 1‐dimethylaziridinium perchlorate.
The synthesis of 3‐deazaorotidine and related nucleoside derivatives of 4‐hydroxy‐2‐pyridone
Authors: Currie Bruce L. , Robins Morris J. , Robins Roland K. 
Published: March 2009

AbstractCondensation of 6‐earbethoxy‐4‐hydroxy‐2‐pyridone or a silyl derivative of 5‐earbomethoxy‐4‐hydroxy‐2‐pyridone with 2′,3′,5′‐tri‐O‐benzoyl‐D‐ribofuranosyl halide has provided the 3‐deaza analogs of orotidine and uridine‐5‐carboxylic acid. The corresponding amides have also been prepared in view of their possible structural relationship to l‐β‐D‐ribohiranosyl nicotinamide. Tri‐O‐benzoyl‐3‐deazauridine was treated with N‐bromosuccinimide to give, after deblocking, 3‐bromo‐4‐hydroxy‐1‐(β‐D‐ribofuranosyl)‐2‐pyridone. The anomeric configuration of these nuclcosides was confirmed by pmr spectroscopy.
Substitution and addition reactions of aziridine with perfluorinated hydrocarbons. Nuclear magnetic resonance spectra of N‐perfluoroalkyl aziridines
Authors: Lautenschlaeger F. , Myhre M. , Hopton F. 
Published: March 2009

AbstractThe reaction of aziridine with chlorotrifluoroethylene, perfluorobenzene, cyclic perfluoroole‐fins and tetracyanoethylene was investigated. The degree of substitution was affected by the ring size of the perfluoroolefin.The temperature dependence of the nuclear magnetic resonance spectra, particularly with respect to the temperature of coalescence of the aziridinyl protons, was investigated.
The crystal and molecular structure of |2‐keto‐|7‐deoxo‐8‐azacstrone methyl ether hydrohromide
Authors: Brown J. N. , Towns R. L. R. , Trefonas L. M. 
Published: March 2009

AbstractThe crystal and molecular structure of 12‐keto‐17‐deoxo‐8‐azaeslrone methyl ether hydro‐bromide (C18H24BrNO2) has been determined by a single crystal, x‐ray diffraction study. The compound crystallizes in the monoclinie space group P21/n with unit cell constants a = 12.024 (2), b = 10.340 (1), c = 14.269 Å (2), β = 104.12° (1). The structure was solved by the heavy atom method and refined by block‐diagonal least‐squares to a final R‐value = 0.036 for the 8.35 independently measured, statistically significant reflections. All hydrogen atoms, including methyl hydrogens, were located.
Total synthesis of camptotheein. I. Synthesis of ethyl 8‐(α‐chlorobutyryloxymethyl)‐7,9‐dioxo‐7,8,9,11 ‐tetrahydroindolizino[ 1,2‐a]quinoline‐8‐carboxylate and related tetracyclic compounds
Authors: Liao T. K. , Nyberg Wayne H. , Cheng C. C. 
Published: March 2009

AbstractA practical synthesis of the 8‐ethoxycarlbonyl‐8‐hydroxymethyl‐7,9‐dioxo‐7,8,9,11‐tetrahydro‐indolizino[ 1,2‐a]quinoline ester of α‐chlorohutyric acid, a tetracyclic intermediate for the total synthesis of the alkaloid camptothecin, was prepared from the anil of o‐aminohenzaldehyde in six steps. Preparative procedures of other related tetracyclic compounds are also reported.
Mass spectra of pyridazines and their N‐oxides
Authors: Ogura Haruo , Sugimoto Shingo , Igeta Hiroshi , Tsuchiya Takashi 
Published: March 2009

AbstractThe mass spectra of pyridazines and their N‐oxides is reported. Previous electron impact studies on aromatic amine N‐oxides reported the appearance of M‐16 and/or M‐17 ion peaks as the usual feature of the fragmentations. In our experiments, the representative fragmentation of the pyridazine N‐oxides involves formation of a M‐30 (M‐NO) ion. The fragmentation patterns substantiated by extensive high resolution studies and the analysis of the appropriate metastable ions.
Synthesis of new s‐triazolo[4,3‐b] pyridazines
Authors: Francavilla P. , Lauria F. 
Published: March 2009

AbstractA new synthesis of s‐triazolo[4,3‐b]pyridazine derivatives has been achieved starting from 3,6‐dichloropyridazine. The method opens the way to substitutions in the 2‐ or 3‐ positions. A tri‐cycloderivative, a bis‐s‐triazolopyridazine, has also been synthesized.
Conformational isomerism of 2‐carboazetidines
Authors: Rodebaugh Richard M. , Cromwell Norman H. 
Published: March 2009

AbstractA number of 1‐alkyl‐2‐carboazetidines have been prepared from the reaction of primary amines with α,γ‐dibromocarbonyl compounds. Several of these new azetidines exhibit doublet carbonyl stretching absorptions in their infrared spectra. A possible explanation of this phenomenon is offered in terms of three rotational conformers which represent various degrees of dipole‐dipole and steric interactions. The cis and trans forms of 1‐t‐butyl‐2‐carbomethoxy‐4‐methylazetidine have been obtained from the reaction of t‐butylamine with methyl α,γ‐dibromovalerate. A detailed examination indicates that the ir and nmr spectra of these epimers are in agreement with the foregoing conformational postulates.