bluuebunny/crossref_metadata_2025_split huggingface dataset:
Problems related to the synthesis of 3‐aziridinyl‐6‐chloropyridazine
Authors: Nyberg Wayne H. , Cheng C. C. 
Published: March 2009

AbstractThe correct structure of the reported 3‐aziridinyl‐6‐chloropyridazine was found to be 3‐[β‐(1‐aziridinyl)ethylamino]‐6‐chloropyridazine, which was confirmed by n. m. r. studies. The relative ease of nucleophilic displacement of a methylsulfonyl group versus a chloro group in equivalent positions on a pyridazine or a pyrimidine ring was compared. It was observed that the chloro rather than the methylsulfonyl group was preferentially replaced, as illustrated by substitution studies of 3‐chloro‐6‐methylsulfonylpyridazine and 4‐chloro‐6‐methylsulfonylpyrimidine.
The synthesis of imidazo[4,5‐c]‐, s‐triazolo[4,3‐b]‐, and tetrazolo[1,5‐b]pyridazines
Authors: Kuraishi Tsukasa , Castle Raymond N. 
Published: March 2009

AbstractThe adenine analog, 7‐aminoimidazo[4,5‐c]pyridazine (XII) and three other members of this previously unknown ring system have been prepared. The adenine analog, 8‐amino‐tetrazolo[1,5‐b]pyridazine (I) has also been prepared together with three other compounds in this ring system. The novel displacement of halogen in nitrogen heterocycles with phosphorus pentasulfide has been extended.
Reisert compound studies. VI. The condensation of aldehydes with 2‐benzoyl‐1,2‐dihydroisoquinaldonitrile
Authors: Popp Frank D. , Gibson Harry W. 
Published: March 2009

AbstractIn 1958 McEwan and coworkers (4) reported the condensation of the lithium salts of 1‐benzoyl‐1,2‐dihydroquinaldonitrile and 2‐benzoyl‐1,2‐dihydroiso‐quinaldonitrile (I) with aldehydes to form esters of secondary alcohols containing the 2‐quinoyl or 1‐iso‐quinoyl (II) group bonded to the carbinol carbon atom. This method was used to devise from appropriate Reissert compounds a convenient synthesis of papaverinol (5) and some attractive intermediates for eventual conversion to the ipecac alkaloids (6).
The synthesis of 9‐acridanylmethyl and 9‐acridinylmethyl ketones
Authors: Sheppard Chester S. , Levine Robert 
Published: March 2009

AbstractA series of new 9‐acridanylmethyl ketones has been prepared by the 9, 10‐addition of the sodium derivatives of a number of ketones to acridine. The 9‐acridanylmethyl ketones were dehydrogenated to the corresponding 9‐acridinylmethyl ketones by either acidic ferric chloride or lead tetraacetate. A route of more limited utility for the synthesis of 9‐acridinylmethyl ketones involves the acylation of 9‐acridinylmethyllithium with certain esters. The attempted ketonic cleavage of α‐(9‐acridinyl)‐β‐ketoesters such as ethyl α‐(9‐acridinyl)isonicotinoylacetate and ethyl α‐(9‐acridinyl)benzoylacetate is an unsatisfactory method for obtaining the corresponding 9‐acridinylmethyl ketones since these ketones are cleaved to 9‐methylacridine under mildly acidic or basic conditions.
2,2′‐P‐phenylenebis(4‐methyl‐5‐phenyloxazole) and other solutes for scintillation counting
Authors: Walker Derek , Waugh Thomas D. 
Published: March 2009

AbstractThe advent of large liquid scintillation counters has created a need for a secondary solute which is more soluble in organic solvents than is 2,2′‐p‐phenylenebis(5‐phenyl‐oxazole) (POPOP, I or II, R‐substituents = H), the preferred secondary solute for small‐scale work.
The stereochemistry of some dihydro‐1,3‐oxazine derivatives
Authors: Chylińska J. B. , Urbański T. 
Published: March 2009

AbstractThe conformations of one dihydro‐1,3‐benzoxazine and two dihydro‐1,3‐naphthoxazines were studied by calculating and measuring their dipole moments.A “semi‐chair” form with a quasi‐axial position of the N‐substituent was found to be most probable.
6‐Substituted acridizinium derivatives
Authors: Bradsher C. K. , Parham J. C. 
Published: March 2009

AbstractThrough quaternization of an acetal of picolinaldehyde with suitable α‐haloalkylarenes, a number of acridizinium salts, having a substituent at the meso position adjacent to nitrogen, have been prepared. Similarly, the ketal derived from α‐acetopyridine has been used to prepare the first acridizinium derivatives having methyl groups at both of the meso positions.
Pyrimidines. XIII. 2‐ and 6‐substituted 4‐pyrimidinecarboxylic acids
Authors: Daves G. Doyle , O'Brien Darrell E. , Lewis Leland R. , Cheng C. C. 
Published: March 2009

AbstractThe “abnormal” behavior of 4,6‐dimethyl‐2‐pyrimidinol towards nitrous acid has been clarified. The reaction between 4‐methyl‐2‐pyrimidinol and nitrous acid has been utilized as a new synthetic procedure for the preparation of several 2‐substituted 4‐pyrimidinecarboxylic acids. 2‐Hydroxy‐4‐pyrimidinecarboxylic acid has also been prepared from 4‐chloro‐2‐methylthiopyrimidine via the trimethylammonium intermediate. 6‐Amino‐ and 6‐thio‐4‐pyrimidinecarboxylic acids have been readily prepared from the previously reported 6‐hydroxy‐4‐pyrimidinecarboxylic acid.
The chemistry of triazine derivatives II. The acylation of 2,4,6‐trimethyl‐s‐triazine to triazinyl ketones and their facile isomerization to acetamidopyrimidines
Authors: Osborne David R. , Wieder William T. , Levine Robert 
Published: March 2009

AbstractA series of triazinyl ketones has been prepared by acylating 2,4,6‐trialkyl‐s‐triazines and these ketones have been isomerized to 4‐acylamidopyrimidine derivatives. A possible mechanism for this isomerization is suggested.
A novel ring closure of 1‐acyl‐2,2‐dialkylhydrazines
Authors: Meyer Robert F. , Cummings Betty L. 
Published: March 2009

AbstractA series of 14 new 2; 4‐substituted‐δ2‐1, 3, 4‐oxadiazolin‐5‐ones was prepared by a novel ring closure of the corresponding l‐acyl‐2, 2‐dialkylhydrazines with phosgene, whereby one alkyl group is lost as alkyl chloride. This new cyclization was carried out too with thiophosgene and with p‐chlorothiobenzoic acid, 2, 2‐dimethylhydrazide to give the corresponding 2,4‐disubstituted‐δ2‐1, 3, 4‐oxadiazoline‐5‐thione, ‐thiadiazolin‐5‐one and ‐thiadiazoline‐5‐thione, respectively.
Cinnoline chemistry X. The infrared spectra of halogen substituted 4‐hydroxy‐ and 4‐mercaptocinnolines
Authors: Shoup Regitze R. , Castle Raymond N. 
Published: March 2009

AbstractThe infrared spectra of a series of 4‐hydroxy‐ and 4‐mercaptocinnolines substituted with fluorine, chlorine or bromine in the 5‐, 6‐, 7‐ and 8‐position have been obtained in potassium bromide discs between 4000 and 400 cm−1. Assignments for most of these bands have been made.
Synthesis of 1‐methyl‐3H‐1,4‐benzodiazepline‐2,5 (1H,4H) ‐dione and derivatives
Authors: Lee Cheuk‐Man 
Published: March 2009

AbstractDerivatives of l‐methyl‐3H‐1, 4‐benzodiazepine‐2,5(1H, 4H)‐dione were synthesized by ring closure of substituted 2[(N‐chloroacetyl‐N‐methyl)amino]benzamides with sodium methoxide in methanol.
Indazole‐3‐carboxylic acids and their derivatives
Authors: Buu‐Hoi N. P. , Hoeffinger J. P. , Jacquignon P. 
Published: March 2009

AbstractThe preparation of indazole‐3‐carboxylic acids from the appropriate isatins by von Auwers' method has been investigated; these acids were used for acceding to the corresponding indazoles and for preparing hydrazides and hydrazones in the indazole series.
Hydrogenation of 3‐(2‐nitrobenzoyl) ‐2‐benzoxazolinone to 1‐hydroxy‐3‐ (2‐hydroxyphenyl) quinazoline‐2,4‐dione
Authors: Sam Joseph , Richmond C. W. 
Published: March 2009

AbstractThe preparations of the compounds noted in the title are described. The reduction of l‐hydroxy‐3‐(2‐hydroxyphenyl)quinazoline‐2, 4‐dione (III) catalyzed by Raney nickel provided 3‐(2‐hydroxyphenyl)quinazoline‐2, 4‐dione (VI).
The synthesis of v‐triazolo[4,5‐c]pyridazines, a new heterocyclic ring system as potential purine antagonists
Authors: Gerhardt G. Anne , Castle Raymond N. 
Published: March 2009

AbstractThe free ring system, v‐triazolo[4, 5‐clpyridazine and several derivatives in this ring system such as the adenine analog, 7‐amino‐v‐triazolo[4, 5‐clpyridazine, have been prepared. In addition, the fully aromatic pyrazino[2, 3‐clpyridazine ring system has been prepared for the first time.
Organic fluoronitrogens. I. The direct fluorination of melon
Authors: Erickson John G. , Brown Harvey A. , Husted Donald R. 
Published: March 2009

AbstractThe action of elemental fluorine upon the complex polyheterocycle, melon, yields products which contain 50% or more of fluorine and are solids or liquids of very low volatility. The structure assigned indicates essential retention of the tri‐s‐triazine structure, with addition of fluorine to most of the double bonds, replacement of hydrogen by fluorine, and a minor amount of cleavage of carbon‐nitrogen bonds.
Pyrimidines. XIV. Synthesis of 1‐substituted 5,6‐dihydrocytosines and an improved synthesis of 1‐substituted uracils
Authors: Cheng C. C. , Lewis Leland R. 
Published: March 2009

Abstract1‐Substituted 5, 6‐dihydrouracils (VI) and 1‐substituted 5, 6‐dihydrocytosines (V) were prepared by cyclization of N‐substituted N‐β‐cyanoethyl ureas (IV) in acid and basic medium, respectively. Compounds N were synthesized from cyanic acid and β‐(substituted amino)propionitriles (III), the latter in turn were prepared from primary amines (I) and acrylonitrile (II).Preparations of 1‐substituted uracils (VII) from VI were carried out by known procedures.
Synthesis of 1‐hydroxyxanthines
Authors: Bauer Ludwig , Nambury C. N. V. , Dhawan Devindra 
Published: March 2009

AbstractThe synthesis of 1‐hydroxy‐7‐alkylxanthines from the corresponding diethyl 1‐alkyl‐4,5‐imidazoledicarboxylates by means of a modified Lossen rearrangement is described. The products were characterized by their spectra and identified by hydrolysis with concentrated hydrochloric acid at elevated temperatures to the corresponding N‐alkyl‐substituted glycines.
Nuclear magnetic resonance spectral analyses of isothiazoles
Authors: Anderson Richard C. 
Published: March 2009

AbstractN.m.r. spectral analyses of isothiazole and its methyl homologs permits assignment of chemical shifts and coupling constants for each of the protons in these molecules. The chemical shift values for hydrogens attached to the isothiazole nucleus substantiate electron density values calculated from molecular orbital theory. In 5‐methylisothiazole, the coupling constant for the hydrogen atom at position 3 and those on the methyl group is larger than for hydrogens attached directly to the isothiazole nucleus at positions 3 and 5.
The synthesis of steroidal 16α,17α‐fused isoxazolines and isoxazolidines
Authors: Culbertson T. P. , Moersch G. W. , Neuklis W. A. 
Published: March 2009

AbstractThe reaction of nitrile oxides with Δ16‐steroids substituted at C‐17 by COCH3, OCOCH3, CN, NHCOCH3 and H afforded 16α, 17α‐[3, 1‐(2‐isoxazolino)]‐steroids. From the reaction of C,N‐diphenylnitrone with pregna‐5,16‐diene‐3β‐ol‐20‐one acetate two isomeric products were isolated, 16α, 17α‐(2, 3‐diphenyl‐3,1‐isoxazolidino)‐pregn‐5‐en‐3β‐ol‐20‐one acetate and 16α, 17α ‐ (2, 3 ‐diphenyl ‐ 1, 3 ‐isoxazolidino)‐pregn‐5‐en‐3β‐01‐20‐one acetate.
Pyridazines. II. The synthesis of amino‐, azido‐ and nitraminopyridazines, tetrazolo[1,5‐b] pyridazines and related nitrogen heterocycles
Authors: Guither William D. , Clark Donald G. , Castle Raymond N. 
Published: March 2009

AbstractThe remaining three diaminopyridazines, 3, 4, 5‐triaminopyridazine and several nitraminopyridazines have been prepared. The structure of 3,4, 5‐triaminopyridazine and the 3, 5‐diamino‐4‐nitropyridazine precursor have been established by n.in.r. analysis. In addition 8‐amino‐6‐chloro‐, 8‐amino‐6‐hydrazino‐ and 8‐amino‐6‐azidotetrazolo‐[1, 5‐b]pyridazine has been synthesized along with 4, 6‐dihydrazino‐ and 4, 6‐diazido‐pyrimidine. Several other chemical transformation of these compounds are described.
The alkylation of 6‐aryl‐6,7‐diazaspiro [3.4]octane‐5,8‐diones
Authors: Brabander Herbert J. , Wright William B. 
Published: March 2009

AbstractThe synthesis of 8‐tert‐aminoalkoxy‐6‐aryl‐6,7‐diazaspiro[3.4]oct‐7‐en‐5‐ones (1) and 6‐tert‐aminoalkyl‐7‐aryl‐6,7‐diazaspiro[3.4]octane‐5,8‐diones has been accomplished. Two synthetic methods are described, each of which yields principally one isomer or the other.
Difluorodiazirine. V. difluoromethyl esters and ethers
Authors: Mitsch Ronald A. , Robertson Jerry E. 
Published: March 2009

AbstractThe preparation of difluoromethyl esters and ethers by the photolytic reaction of difluorodiazirine with acids and alcohols, respectively, is described. Difluoromethyl benzoate is converted, under mild conditions, to methyl benzoate, benzamide and benzanilide by reaction with methanol, ammonium hydroxide and aniline, respectively. The difluoromethyl esters are activated to nucleophilic reaction by virtue of the α‐fluorine substitution.
Analogs of tetrahydrofolic acid. XXVI. synthesis of some 5‐aryl and 5‐aralkyl pyrimidine‐6‐carboxylic acids and their effect on dihydrofolic reductase and thymidylate synthetase
Authors: Baker B. R. , Jordaan Johannes H. 
Published: March 2009

Abstract2‐Amino‐4‐hydroxy‐5‐(4‐phenylbutyl)pyrimidine‐6‐carboxylic acid (V) was synthesized from isopropyl 2‐ethoxalyl‐6‐phenylhexanoate (XIII) by conversion to acyl guanide (XV) with guanidine followed by anhydrous acid catalyzed ring closure to ethyl 2‐amino‐α‐(4‐phenylbutyl)‐4‐oxo‐2‐imidazoline‐Δ5,α‐acetate (XXIII) and base catalyzed rearrangement to V; similarly, p‐chlorophenylacetonitrile was converted to 5‐(p‐chlorophenyl)‐2,4‐diaminopyrimidine‐6‐carboxylic acid (VIII). Claisen condensation of isopropyl 6‐phenylhexanoate (XI) or p‐chlorophenylacetonitrile with ethyl trifluoroacetate followed by condensation with guanidine afforded 2‐amino‐5‐(4‐phenylbutyl)‐6‐(trifluoromethyl)‐4‐pyrimidinol (XXVI) and 5 ‐ (p‐chlorophenyl) ‐2,4 ‐diamino‐6‐(trifluoromethyl)pyrimidine (XXXIV). Evaluation of V, VIII, XXVI, and XXXIV as inhibitors of dihydrofolic reductase showed that the 6‐carboxyl, 6‐trifluoromethyl, and 6‐carbethoxy groups greatly reduced the effectiveness as inhibitors of dihydrofolic reductase compared to the corresponding 6‐methyl derivatives. The inhibition data appear to make unlikely the possibility of the pyrimidines binding to the enzyme by four hydrogen bonds as propounded by Zakrzewski (19) or by binding through a charge‐transfer complex, but supports the concept (18) of an anionic‐cationic interaction for the protonated 2,4‐diaminopyrimidines; a weak base ‐weak acid interaction for a non‐protonated pyrimidine that is stronger than a hydrogen bond is also proposed.
Liquid scintillators. XIII. steric inhibition of resonance in liquid scintillators
Authors: Taber Richard L. , Daub Guido H. , Hayes F. Newton , Ott Donald G. 
Published: March 2009

Abstract2″,3′ ‐ Dimethyl ‐ p ‐ quaterphenyl (I), 2″, 3′, 5′, 6″ ‐tetramethyl ‐ p ‐ quaterphenyl (II), 6,7 ‐ dihydro ‐ 6 ‐ methyl ‐ 3, 9 ‐ diphenyl ‐ 5H ‐ dibenz[c,e]azepine (III), 5,7 ‐ dihydro ‐ 3, 9 ‐ diphenyl ‐ dibenzo[c,e]thiepin (IV), 5,7 ‐ dihydro ‐ 3,9 ‐ diphenyldibenzo[c,e]selenepin (V), and 6, 6 ‐ dicarbethoxy ‐ 6,7 ‐ dihydro ‐ 3,9 ‐ diphenyl ‐ 5H ‐ dibenzo[a,c]cycloheptene (VI) have been synthesized and screened as potential primary liquid scintillation solutes. The scintil‐ lation properties of I, II, III, IV, V, and VI have been compared with 2,7‐diphenyl‐ fluorene (VII) (4), 9,10‐dihydro‐2,7‐diphenylphenanthrene (VIII) (5), and 5,7‐dihydro‐ 3, 9‐diphenyldibenz[c,e]oxepin (IX) (5). The relative pulse‐heights of I, VI, VII, VIII, and IX at 3 mM in toluene gave a linear relationship when plotted against the cos2 of the respective estimated angles of torsion about the 1″. 4′‐bond in the p‐quaterphenyl system. The azepine III, thiepin IV, selenepin V, and tetramethyl‐p‐quaterphenyl II were very poor scintillators in toluene solution.
Pyrazolo [3,4‐b]pyridines and pyrazolo[3′,4′:6,5]pyrido[2,3‐d]pyrimidines
Authors: Cottis Steve G. , Clarke Priscilla B. , Tieckelmann Howard 
Published: March 2009

Abstract3,6‐Diamino‐5‐cyanopyrazolo[3,4‐b]pyridine (III) and 1‐methyl‐3, 6‐diamino‐5‐cyanopyrazolo[3,4‐b]pyridine (IV) were formed by treatment of 2‐amino‐6‐chloro‐3, 5‐dicyanopyridine with hydrazine and methylhydrazine. Pyrazolo[3′,4′:6,5]pyrido[2,3‐d]pyrimidines were formed from IV and from a number of its derivatives.
Acridizinium betaines
Authors: Bradsher C. K. , Parham J. C. , Turner J. D. 
Published: March 2009

AbstractThe quaternary salts formed by reaction of tolyl sultone (2, 1, 3H‐benzoxathiole‐1, 1‐dioxide) with 2‐(1,3‐dioxolan‐2‐yl)‐ or 2‐(2‐methyl[1, 3]dioxolan‐2‐yl)pyridine may be cyclized in acid to afford the betaines derived from 7‐sulfo‐ and 7‐sulfo‐11‐methylacridizinium hydroxides. Similarly 1‐(1,3‐dioxolan‐2‐yl)isoquinoline may be converted to the betaine of 9‐sulfobenzo[a]acridizinium hydroxide.The sodium salt of 2‐(3′‐sulfobenzoyl)pyridine may be quaternized with benzyl bromide and the resulting betaine cgclized to afford the betaine of 11‐(3′‐sulfophenyl)acridizinium hydroxide.
Benzo[b]thiophene derivatives. VII. An abnormal substitution product from 3‐chloromethylbenzo[b]thiophene
Authors: Campaigne E. , Neiss E. S. 
Published: March 2009

AbstractThe alkylation of cyanide ion with 3‐chloromethylbenzo[b]thiophene gave a higher yield of benzo[b]thiophene‐3‐acetonitrile in dimethyl sulfoxide than in alcohol, and in addition 2‐cyano‐3‐methylbenzo[b]thiophene was obtained as a by‐product in this solvent. The abnormal product was prepared by an alternative, unequivocal synthesis. The isomers were hydrolyzed to their respective acids, which were reduced to 3+(β‐hydroxyethyl)benzo[b]thiophene and 2‐hydroxymethyl‐3‐methylbenzo[b]thiophene. The ultraviolet and nuclear magnetic resonance spectra of these compounds are reported.
Imidazo[4,5‐d]pyridazines. IV. Synthesis of 4,7 disubstituted derivatives and 1‐benzyl‐2‐substituted thio derivatives
Authors: Gerhardt G. Anne , Aldous Duane L. , Castle Raymond N. 
Published: March 2009

AbstractSeventy‐five new imidazo[4,5‐d]pyridazines and three new imidazoles have been prepared for antitumor testing. Antitumor screening results are reported for thirty‐five of these compounds. No significant activity was observed.
The mass spectra of oxygen heterocycles I. The 4‐hydroxy‐3‐phenylcoumarins (isoflavonols)
Authors: Pelter A. , Stainton P. , Johnson A. P. , Barber M. 
Published: March 2009

AbstractThe unique breakdown patterns of the 4‐hydroxy‐3‐phenylcoumarins (isoflavonols) in the mass spectrometer have been examined. Explanations of the fragmentations found have been confirmed by deuteration studies and by an examination of the mass spectra of 4‐methoxy‐3 ‐phenylcoumarins. The scheme has been extended 4 to 7‐dihydroxycoumarin, which is contrasted with 4‐methyl.‐7‐hydroxycoumarin.
The mass spectra of oxygen heterocycles. II. The mass spectra of some flavonoids
Authors: Pelter Andrew , Stainton P. , Barber M. 
Published: March 2009

AbstractThe mass spectra of the flavones apigenin and acacetin have been reported by Wilson and Reed (1) whilst the mass spectrum of flavone itself has been described by Barnes and Occolowitz (2). A discrepancy between the results obtained lies in the importance assumed by breakdown via a Diels‐Alder reaction (described as mode A in paper I (3) of this series) in the natural products as compared with the parent compound.
Morphanthridines I. 11‐aminoalkylidene‐and ll‐(4‐Piperidylene)‐5,6‐dihydromorphanthridines
Authors: Drukker Alexander E. , Judd Claude I. , Spoerl Joan M. , Kaminski Frank E. 
Published: March 2009

AbstractNew methods are described for the preparation of 5,6‐dihydro‐11‐morphanthridone, 5‐substituted 5,6‐dihydro‐11‐morphanthridones and nuclear halogenated derivatives. Basic Grignard reagents convert these ketones to carbinols, which through dehydration affords a convenient route to straight chain and cyclic 11‐aminoalkylidene derivatives.
Synthesis of fused imidazo‐heterocyclic systems
Authors: Werbel Leslie M. , Zamora Maria L. 
Published: March 2009

AbstractThe reaction of phenylacyl bromide and a variety of α‐aminoheterocycles was investigated to determine its applicability to the preparation of fused imidazo‐heterocyclic systems. The imidazo[1, 2‐a]pyrazine, imidazo[1, 2‐b]pyridazine, and imidazo[1,2‐a]‐benzimidazole systems and some variations of the imidazo[1,2‐a]pyridine, imidazo[2,1‐b]‐thiazole, imidazotriazine, imidazo[2,1‐b]‐1,3,4‐thiadiazole systems are described.
Cyclizations of 3,4,5‐triamino‐s‐triazole (guanazine) and 3,4‐diamino‐5‐mercapto‐s‐triazole with acetic anhydride
Authors: Child Ralph G. , Tomcufcik Andrew S. 
Published: March 2009

AbstractCyclizations of either guanazine (I) or 3,4‐diamino‐5‐mercapto‐s‐triazole (VI) with acetic anhydride leads to 3‐amino‐6‐methyl‐s‐triazolo[4,3‐b]‐s‐triazole and 5‐amino‐2‐methyl‐s‐triazolo[3,4‐b]‐1, 3,4‐thiadiazole, respectively, as well as their acetyl derivatives.
Imidazo [1,2‐a] pyridinium salts
Authors: Bradsher C. K. , Litzinger E. F. , Zinn M. F. 
Published: March 2009

Abstract2‐Alkylamino‐ or arylaminopyridines react directly with α‐bromoketones to afford 1‐alkyl‐ or 1‐arylimidazo[1,2‐a]pyridinium salts with substituents at position 2. Use of chloroacetaldoxime as the quaternizing agent yields (after hydrolysis) the imidazo‐[1,2‐a]pyridinium ion with no substituent at position 2. The earlier supposition that alkylation of imidazo[1,2‐a]pyridines occurs in position 1 has been shown to be correct.It has been pointed out that the 1‐substituted imidazo[1, 2‐a]pyridinium system is but one of a group of aromatic heterocyclic systems isoelectronic with the quinolizinium system.
Synthesis of cis,cis‐4,8‐dimethyl‐cis‐2,6‐dioxadecahydroazulene
Authors: Krapcho A. Paul , Mundy Bradford P. 
Published: March 2009

AbstractIn the course of investigating the preparation of a cis‐decahydroazulene (bicyclo‐[5.3.0]decane) ring system, a dioxa analog was synthesized as a model compound. This paper describes the preparation of the hitherto unknown heterocyclic system cis,cis‐4, 8‐dimethyl‐cis‐2, 6‐dioxadecahydroazulene (IX).
Azasteroids II. Approaches to the 13‐azaequilenin system
Authors: Schleigh William R. , Catala Adria , Popp Frank D. 
Published: March 2009

AbstractThe synthesis of N‐[2‐(1‐naphthyl)ethyl]succinimide, N‐[2‐(1‐naphthyl)ethyl]pyrrolidone and the corresponding 3,4‐dihydro compounds is described. The pyrrolidones have been converted into 11,12,16,17‐tetrahydro‐13‐azacyclopenta[a]phenanthrene and 6,7,11‐12,16,17‐hexahydro‐13‐azacyclopenta[a]phenanthrene. These two compounds were then converted to XIX and XXII. The former compound is a salt of (+) 3‐desoxy‐17‐desoxo‐13‐azaequilenin.
The syntheses of 5,6‐dihydroxyindole and some of its derivatives
Authors: Benigni Joseph D. , Minnis R. L. 
Published: March 2009

Abstract5,6‐Dihydroxyindole (VIa) and its two mono O‐methyl analogs (VIb,c), and their 2‐carboxylic acids (XII), tryptamines (XV), and N‐acetyltryptamines (XVII) have been synthesized. An improved syntheses of the 5,6‐dihydroxyindoles has been developed.
Ten π‐electron nitrogen heterocyclic compounds III: The synthesis and NMR spectra of some 1,6‐naphthyridines
Authors: Paudler William W. , Kress Thomas J. 
Published: March 2009

AbstractThe synthesis of 1,6‐naphthyridine and of some 4‐substituted 1,6‐naphthyridines are described. The analysis of the NMR spectra and a correlation between the chemical shifts of H2, H5, H7, H8, and Brown's σp+ values are reported.
Correlation of NMR chemical shifts of 2‐methyl protons of substituted benzazoles with hammett's substituents constants
Authors: Di Modica Gaetano , Barni Ermanno , Gasco Alberto 
Published: March 2009

AbstractThe chemical shifts of 2‐methyl protons of twenty one 5‐ and 6‐ substituted benzazoles determined in carbon tetrachloride solution, were plotted against the Hammett substituent constants using δm for groups in the 5‐ position and δp for groups in the 6‐ position, obtaining satisfactory linear correlations. These results are taken to indicate that electronic effects are transmitted to the 2‐position predominantly through the nitrogen atom and that virtually no transmission occurs through the hetero atom. The deshielding effect of the hetero atom is opposite to the electronegativity and this may be qualitatively explained in terms of different aromaticity of these heterocycles.