bluuebunny/crossref_metadata_2025_split huggingface dataset:
5‐HT 1A and 2A receptor positive cells in the cerebella of mice and human and their decline during aging
Authors: Yew David T. , Yeung Lai‐Yin , Wai Maria Sen‐Mun , Mak Ying T. 
Published: April 2009

AbstractThis study evaluated the 5‐HT1A and 5‐HT2A receptor positive cells in the cerebella of mice and human by immunocytochemistry. Mice were of ages 1, 3, and 12 months whereas the human subjects were divided into two groups, a younger 57–78 years old group and an older 82–91 years old group. Both 5‐HT1A and 5‐HT2A receptor positive cells were observed in the molecular and granular layers of the cerebella of mice and human. Although there was a decline in these positive cells during aging, no regional difference in the positive cells were observed in the anterior, middle, and posterior regions of the cerebella. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.
Maximum directed cuts in digraphs with degree restriction
Authors: Lehel Jenö , Maffray Frédéric , Preissmann Myriam 
Published: April 2009

AbstractFor integers m, k≥1, we investigate the maximum size of a directed cut in directed graphs in which there are m edges and each vertex has either indegree at most k or outdegree at most k. © 2009 Wiley Periodicals, Inc. J Graph Theory
Acyclic edge coloring of graphs with maximum degree 4
Authors: Basavaraju Manu , Chandran L. Sunil 
Published: April 2009

AbstractAn acyclic edge coloring of a graph is a proper edge coloring such that there are no bichromatic cycles. The acyclic chromatic index of a graph is the minimum number k such that there is an acyclic edge coloring using k colors and is denoted by a′(G). It was conjectured by Alon, Sudakov, and Zaks that for any simple and finite graph G, a′(G)⩽Δ + 2, where Δ=Δ(G) denotes the maximum degree of G. We prove the conjecture for connected graphs with Δ(G)⩽4, with the additional restriction that m⩽2n−1, where n is the number of vertices and m is the number of edges in G. Note that for any graph G, m⩽2n, when Δ(G)⩽4. It follows that for any graph G if Δ(G)⩽4, then a′(G)⩽7. © 2009 Wiley Periodicals, Inc. J Graph Theory 61: 192–209, 2009
Generating 5‐regular planar graphs
Authors: Ding Guoli , Kanno Jinko , Su Jianning 
Published: April 2009

AbstractFor k=0, 1, 2, 3, 4, 5, let ${\cal{P}}_{k}$ be the class of k ‐edge‐connected 5‐regular planar graphs. In this paper, graph operations are introduced that generate all graphs in each ${\cal{P}}_{k}$. © 2009 Wiley Periodicals, Inc. J Graph Theory 61: 219–240, 2009
Anti‐Ramsey numbers of doubly edge‐critical graphs
Authors: Jiang Tao , Pikhurko Oleg 
Published: April 2009

AbstractGiven a graph H and a positive integer n, Anti‐Ramsey number AR(n, H) is the maximum number of colors in an edge‐coloring of Kn that contains no polychromatic copy of H. The anti‐Ramsey numbers were introduced in the 1970s by Erdős, Simonovits, and Sós, who among other things, determined this function for cliques. In general, few exact values of AR(n, H) are known. Let us call a graph H doubly edge‐critical if χ(H−e)≥p+ 1 for each edge e∈E(H) and there exist two edges e1, e2 of H for which χ(H−e1−e2)=p. Here, we obtain the exact value of AR(n, H) for any doubly edge‐critical H when n⩾n0(H) is sufficiently large. A main ingredient of our proof is the stability theorem of Erdős and Simonovits for the Turán problem. © 2009 Wiley Periodicals, Inc. J Graph Theory 61: 210–218, 2009
Heterocycles from substituted amides III. 1,2,3‐Oxathiazolidin‐4‐one 2‐oxides from thionyl chloride and α‐hydroxyacylanilides
Authors: Chupp John P. 
Published: April 2009

AbstractA new heterocyclic series was synthesized for the first time, from reaction of thionyl chloride with α‐hydroxyacylanilides (1). Structural features of the resulting 1,2,3‐oxathiazolidin‐4‐one 2‐oxides (2) are discussed with particular reference to their spectral properties, and are compared with the previously reported 1,2,3‐oxathiazolidine 2‐oxides (3).
Some derivatives of indeno[2,1‐g]pteridine
Authors: Saint‐Ruf C. 
Published: April 2009

AbstractThe condensation of indantrione monohydrate (ninhydrin) with ortho‐diamines derived from pyridine and pyrimidine led to the synthesis of several new indeno[2,1‐g]pteridine derivatives. The structure of these compounds is discussed and their physical properties described.
Polar cycloaddition reactions of some 2,3‐disubstituted isoquinolinium salts
Authors: Bradsher C. K. , Day F. Howard 
Published: April 2009

AbstractThe addition of four vinyl ethers and of cyclopentadiene to 2,3‐dimethylisoquinolinium salts occurs stereoselectively affording only syn adducts. The attack of nucleophiles on the vinyl ether adducts (4–9) occurs at position 3. Similar stereoselective cycloadditions may be carried out using berberinium chloride as the electrophile.
Heterocyclic derivalives of naphthalene‐1,8‐dicar boxylie anhydride. Part III. Benzo[k,l] thioxanthene‐3,4‐dicarboximides
Authors: Grayshan P. H. , Kadhim A. M. , Perters Arnold T. 
Published: April 2009

AbstractCondensation of 4‐bromo‐ (4) and 4‐nilro‐l,8‐naphthalimides (5) with 2‐aminobenzenethiol gave 4‐(2‐aminoulicnylthio)‐1,8‐naphthalimides (7). Cyclisalion of 7 by the: Pschorr reaction afforded benzo[k,l] thioxanthene‐3,4‐dicarboximides (8), also obtained by reaction ol amities with benzo[k,l] thioxanthene‐3,4‐dicarboxylie anhydride (11).
1,2,4‐Triazines. XII. Syntheses of 5‐carboxarnido‐1,2,4‐triazines via an addition‐oxidation reaction
Authors: Krass Dennis K. , Paudler William W. 
Published: April 2009

Abstract5‐Unsubstituted 1,2,4‐triazines, when treated with potassium cyanide suspended in moist dioxane afford 5‐carhoxamido as well as 5,5′ ‐bi‐1,2,4‐triazinyl derivatives. A probable reaction sequence is described.
Synthesis and reactions of 2‐aryl‐3‐(dimethylamino)acroleins
Authors: Coppola Gary M. , Hardtmann Goetz E. , Huegi Bruno S. 
Published: April 2009

AbstractThe preparation of a number of novel 2‐aryl‐3‐(dimethylamino)acroleins and their hydrolyses to 2‐arylmalondialdehydes is described. Reactions of the acroleins with amines are discussed as well as the conversion of the 2‐arylmalondialdehydes into 3‐chloro and 3‐alkoxyacroleins.
Properties of lipoic acid analogs
Authors: Shih Jason C. H. , Williams Paul B. , Wright Lemuel D. , Mccormick Donald B. 
Published: April 2009

AbstractTwo chain‐shortened analogs of lipoic (1,2‐dithiolane‐3‐pentanoic) acid, viz. bisnor‐lipoic (1,2‐dithiolane‐3‐propanoic) and tetranorlipoic (1,2‐dithiolane‐3‐carboxylic) acids, have been chemically synthesized. The ir, uv, pmr, and mass spectroscopic properties and paper, thin‐layer, and column chromatographic mobilities of lipoic acid and its analogs were investigated and are given.
Pyrolysis of 2‐(2‐azidobenzoyl)pyridine and 3‐(2‐Pyridyl)‐2,1‐ benzisixazoles. Prepration and chemistry of some pyrido[1,2‐b]cinnolin‐6‐ium hydroxide inner salts
Authors: Ning Robert Y. , Chen Wen Yean , Sternbach Leo H. 
Published: April 2009

AbstractThe pyrolysis of 3‐(2‐pyridyl)‐2,1‐benzisoxazoles 5A, 5B, and 5C (A: unsubstituted; B: 5‐bromo; C: 5,7‐dibromo) at about 215° afforded 5,11‐dihydro‐11‐oxopyrido [1,2‐b] cinnolin‐6‐ium hydroxide inner salt 6A, the 2‐bromo (6B) and the 2,4‐dibromo (6C) compounds respectively in high yields. X‐ray crystallographic analysis of 6B unambiguously confirmed the structure. The benzisoxazoles 5A‐5C were obtained from the pyrolysis of the corresponding 2‐(2‐azidobenzoyl) pyridines 2A‐2C at about 112°. While 2A and 2B afforded the corresponding benzisoxazoles 5a and 5B in 82% and 51% yields respectively, 2‐(2‐azido‐3,5‐dibromobenzoyl)pyridine (2C) afforded a mixture of the benzisoxazole 5C and the tricyclic compound 6C, isolated 43% and 41% yields respectively.The properties of the novel mesoionic compounds of type 6, their oxidative and reductive ring cleavage products together with alkylation and catalytic hydrogenation products are described. Electrophilic substitutions, substitutions in position 11 via the 11‐thiones 11 and other miscellaneous trans of 6 are also presented.
Definition of the predominant tautomeric form of 3‐methyl‐1‐phenylpyrazoline‐5‐thione in solution by 1 H and 1 3C NMR spectroscopy
Authors: Bergman Joseph John , Lynch Brian Maurice 
Published: April 2009

AbstractConjoint use of pmr allylic coupling constants and of 1 3C nmr chemical shift patterns defines the predominant tautomeric form of 3‐methyl‐1‐phenylpyrazoline‐5‐thione in solution in aprotic dipolar and in non‐polar solvents as the thiol species, 3‐methyl‐1‐phenylpyrazole‐5‐thiol. The tautomeric preference thus differs from that of the oxygen analog, and is opposite to that noted for thiol‐thione tautomerism in six‐membered heteroaromatic species.
Cation radicals. XXVIII. Isolation and some reactions of dibenzodioxin cation radical perchlorate
Authors: Shine Henry J. , Shade Lewis R. 
Published: April 2009

AbstractPreparation and isolation of dibenzodioxin cation radical perchlorate (2) by oxidation of dibenzodioxin in ethyl acetate‐lithium perchlorate at a platinum anode has been achieved. Reasonably pure 2 in amounts of 150–200 mg. were obtained reliably and reproducibly. Reaction of 2 with both nitrite and nitrate ions gave 2‐nitrodibenzodioxin (3). Reaction of 2 with pyridine gave N‐(2‐dibenzodioxinyl)pyridinium perchlorate (4). Reaction with water gave, as anticipated, the stoichiometric amount of dibenzodioxin. Reaction with ammonia, propylamine, t‐butylamine, and cyanide ion also gave dibenzodioxin with no evidence that nucleophilic substitution had occurred. It is believed that the formation of 3 and 4 represent the first examples of nucleophilic substitution into dibenzodioxin via its cation radical.
1.6‐Naphathyridines II. 2,3‐Distributed derivatives and some new tricyclic ring systems
Authors: Hawes Edwared M. , Gorecki Dennis K. J. 
Published: April 2009

AbstractA number of new 2‐ and/or 3‐substituted 1,6‐naphthyridines were prepared via Friedländer reactiona with 4‐aminonicotinaldehyde and methylene compounds containing α‐ketones, Methylene compounds with two reactive α‐centers were also used. The facile conversion of the 1,6‐naphthyridines into new tricylic ring system is reported.
The synthesis and properties of pyridazino[4,3‐e] ‐as‐triazines and pyridazino[4,5‐e] ‐as‐triazines, two novel condensed pyridazine ring systems
Authors: Chesney Dennis K. , Castle Raymond N. 
Published: April 2009

AbstractThe compounds prepared in the novel pyridazino[4,3‐e]‐as‐triazine ring system are: 8‐chloro‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (21), 8‐chloro‐2,4‐dimethyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (23), 8‐chloro‐2‐ethyl‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐ triazine (24), 4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine‐8‐thione (25), 4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (26), 2,4‐dimethyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (27), and 2‐ethyl‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (28). In the novel pyridazino[4,5‐e]‐as‐triazine ring system the following compounds were prepared: 1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (31), 3‐methyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (32), 3‐ethyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (33), and 1‐methyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (35). The preparation of a number of previously unreported intermediates and compounds for structure proof are also described.
Chemistry of thienopyridines. XVII. Direct halogenation of thieno[2,3‐b]pyridine
Authors: Klemm L. H. , Merrill R. E. , Lee F. H. W. , Klopfenstein C. E. 
Published: April 2009

AbstractThieno [2,3‐b] pyridine (Ia) was converted into its 3‐chloro, 3‐bromo, and 3‐iodo derivatives by means of elemental halogen, silver sulfate, and sulfuric acid. Bromine in a buffered chloroform solution of la also gave the 3‐bromo compound (57% yield). Chlorine plus a refluxing mixture of Ia, chloroform, and water produced both the 3‐chloro and the 2,3‐dichloro derivatives. Various transformation products of these halothienopyridines (including the 2‐nitro‐3‐halo compounds) are described and mass spectral fragmentation patterns are presented.
The use of the wittig reaction in the modification of purine nucleosides
Authors: Montgomery John A. , Laseter Anne G. , Hewson Kathleen 
Published: April 2009

AbstractThe Pfitzner‐Moffatt oxidation of 6‐chloro‐9‐(2,3‐O‐isopropylidene‐β‐D‐ribofuranosyl)purine, 9‐(2,3‐O‐isopropylidene‐β‐D‐ribofuranosyl)‐6‐(methylthio)purine, and 2′,3′‐O‐isopropylideneadenosine gave the corresponding 5′‐aldehydes (3, 13, and 4), which were allowed to react with a number of Wittig ylids. The resulting olefins, primarilytrans, were reduced either catalytically or with diimide before removal of the 2′,3′‐O‐isopropylidene groups to give the desired 5′‐substituted purine ribonucleosides.
The reaction between 3,3‐bis(methoxyphenyl)‐3H‐naphtho[2,1‐b]pyran and 1,3‐bis(methoxyphenyl)‐1H‐naphtho[2,1‐b]pyran, 2,2‐diphenyl‐2H‐chromen and 2,4‐diphenyl‐4H‐chromen, and related compounds
Authors: Cotterill W. David , Iqbal Muhammad , Livingstone Robert , Walshaw Maurice V. 
Published: April 2009

AbstractThe reaction between 3,3‐bis(methoxyphenyl)‐3H‐naphtho[2,1‐b]pyran and 1,3‐bis(methoxyphenyl)‐1H‐naphtho[2,1‐b]pyran under acid conditions gives a 7a,15a‐dihydro‐7a,15‐bis(methoxyphenyl)‐16‐[2,2‐bis(methoxyphenyl)‐l‐vinyl]dinaphtho‐[2,1‐b:2,1‐g]‐4H,5H‐pyrano[2,3‐b]‐pyran.
Electron impact fragmentation of some tetramethyl derivatives of thiathrene and phenoxathiin
Authors: Saint‐Ruf G. , Servoin‐Sidoine J. , Coic J. P. 
Published: April 2009

AbstractMass spectra of thiathrene and three tetramethylthiathrenes (II), (III) and (IV) are reported and discussed. The principal mode of fragmentation of these compounds consists of the loss of sulphur to give the corresponding dibenzothiophene ion. The general pattern of electronolytic decomposition among the tetramethylthianthrenes is, however, much more complex. The mass spectrum of 2,3,7,8‐tetramethylphenoxathiin (VI) is also reported and compared with the spectrum of the corresponding thianthrene derivatives.
Kinetic studies of nucleophilic substitution of various halothiadiazoles with methoxide ion
Authors: Modarai B. , Ghandehari M. H. , Massoumi H. , Shafiee A. , Lalezari I. , Badali A. 
Published: April 2009

AbstractA number of halo‐substituted 1,2,3 and 1,3,4‐thiadiozoles have been prepared, their reactivity towards methoxide ion have been studied and the kinetic parameters are reported.
Investigation of the grewe codeine method. Attempts to achieve a practical synthesis
Authors: Degraw J. I. , Christensen J. C. , Brown V. H. , Cory M. J. 
Published: April 2009

AbstractThe svnthesis of 1‐(2′‐bromo‐4′‐methoxy‐5‐hydroxybenzyl)‐6‐keto‐Δ4a‐5‐decahydroisoquinoline (IX) is described. Efforts to cyclize this intermediate or its N‐acyl derivatives in acidic media to morphinan products were unsuccessful. The presence of the para‐bromine blocking group apparently exerts a deactivating influence on the phenolic ring. 1‐(3′,5′‐Dihydroxy‐4′‐methoxybenzyl)‐6‐methoxy‐1,2,3,4,5,8‐hexahydroisoquinoline (XVIII) was readily cyclized to 2‐hydroxydihydronorthebainone. However, attempts to remove the 2‐hydroxy group and subsequent conversion to dihydronorcodeine were unrewarding.
Investigation on the isomerization of 2‐amino‐3‐aziridino‐1,4‐naphthoquinones to benzo[g]quinoxalines
Authors: Casini Giovanni , Claudi Francesco , Grifantini Mario , Martelli Sante 
Published: April 2009

AbstractThe course of the hydriodic acid‐catalysed and iodide‐catalysed isomerization of various 2‐amino‐3‐substituted‐aziridino‐1,4‐naphthoquinones (I) to 1,2,3,4,5,10‐hexahydrobenzo[g]‐quinoxaline‐5,10‐diones (III) is investigated, and steric aspects of the reaction are also considered. Only in the case of the phenylaziridino derivative (Ie) does hydriodic acid afford direct cyclization to the corresponding benzoquinoxalinedione (IIIe); in all other cases the hydriodides (V) of the cleavage products (II) are obtained, and liberation of the free bases (II) results in cyclization to the corresponding benzoquinoxalinediones (III) when the aziridine ring is monosubstituted or trans disubstituted, with retention of configuration in the latter case. In contrast, the free bases (II) obtained from cis disubstituted (I) are relatively stable and cyclize with excess iodide yielding trans disubstituted (III). Correspondingly, monosubstituted and trans disubstituted I undergo iodide‐catalysed isomerization to III whereas cis disubstituted I do not react.
Some 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐i,j]quinolines
Authors: Steak Edgar A. , Fletcher Lynn T. , Carabateas Clarissa D. 
Published: April 2009

AbstractOn the basis of structural features which relate 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐i,j]quinolines to indoles, several representative groups of derivatives were synthesized.
Elude de la réaction du β‐aminocrotonitrile et du α‐formyl phénylacétonitrile avec l'hydrazine: Synthèse d'amino‐7 pyrazolo[1,5‐a]pyrimidines
Authors: Alcalde Ermilas , De Mendoza Javier , Elguero José , Marino Juan , Garcia‐Marquina  , Almera Consuelo 
Published: April 2009

AbstractThe three compounds C8 H10N4 which arise from reaction of hydrazine and β‐aminocrotonitrile have been identified: the formation of anazine, a 3(5)‐amino 5(3)‐methyl pyrazole derivative and a 7‐amino pyrazolo [1,5‐a] pyrimidine has been demonstrated. The relationships among these compounds and with the methyl‐aminopyrazole have been studied.
Thiazolo [3,2‐b]‐s‐triazole
Authors: Tamur Yasumitsu , Hayashi Hironori , Sacki Eiko , Kim Joong‐Hyup , Ikeda Masazumi 
Published: April 2009

Abstract2‐Formamidothiazole and O‐mesitylenesulfonylhydroxylamine readily gave 3‐umino‐2‐form‐amidothiazolium mesitylenesulfonate that with polyphosphoric acid gave thiazolo [3,2‐b]‐s‐triazole. triazole. In its nmr spectrum, a long‐range coupling of 1.4 Hz between H‐2 and H‐6 is observed.
The. Synthesis and chelation properties of N‐substituted amidrazones and related azines containing the 2‐pyridyl group
Authors: Case Francis H. , Schitt A. A. , Fang T. A. 
Published: April 2009

AbstractThe. preparation and properties of certain N‐substituted amidrazones from thioamides containing the 2‐pyridyl group and the azines derived from them by reaction with benzaldehyde and 2‐pyridinecarboxaldehyde is described.
Pyridazines. LXV. Reactions of some I‐phenacylazolopyridazinium halides with 2,3‐diphenylcyclopropenone, ‐thione, or hydrazine
Authors: Koren B. , Stanovnik B. , Tišler M. 
Published: April 2009

AbstractI‐Phenacylazolopyridazinium bromides reacted with 2,3‐diphenylcyclopropenone or ‐thione in the presence of triethylaminc to give 3,4,6‐triphenyl‐2‐pyrone or ‐2‐thiopyrone and the corresponding azolopyridazine. Quaternized azolopyridazines reacted with hydrazine to give either 3,6‐diphenylpyridazine and the corresponding azoloazine or hy ring opening of the azine part to give 1‐methyl‐2‐(pyrazolyl‐5′)imidazole.
Reaction of ω‐cyanoacetophenone and some of its derivatives with secondary amines. New synthesis of aminopyridine derivatives
Authors: Purrello G. , Vullo A. Lo 
Published: April 2009

Abstractω‐Cyanoacetophenone (1a) and its derivatives 1b‐c react with morpholine (or piperidine) to give mainly 2,4‐diaryl‐3‐eyano‐6‐morpholino‐ (or piperidino‐) pyridine derivatives (5); relative β‐aminoeinnamonitriles 6 and very small amounts of amidines 4 are also obtained. When pyrrolidine is used compounds 5 cannot be detected and enamines 6 are the main product.A mechanism involving the intermediate formation of enamines 6 (as electrophiles) and of carbanions 11 (as nucleophiles) is proposed to explain this new synthesis of aminopyridine derivatives.
Action of amines and carbonyl reagents on 3,5‐diphenyl‐4‐pyrone and its thio analogue
Authors: El‐Kholy Ibrahim El‐Sayed , Mishrikey Marcos Michael , Atmeh Ragheb Fuad 
Published: April 2009

AbstractSeveral N‐substituted, 3,5‐diphenyl‐4‐pyridones and 4‐thiopyridones were obtained by the action of amines on 3,5,‐diphenyl‐4‐pyrone and its thio analogue. With hydrazine hydrate, the products were 1‐amino‐3,5‐diphenyl‐4‐pyridone and the corresponding thione. The spectral characteristics ol these pyridones were studied.
Novel polycyclic heterocycles. XII. Reactions of 1,2‐dihydro‐11‐(trifluoromethyl)‐3H‐7H‐quino[8, 1‐cd] [1,5]‐benzoxazepin‐3‐one with aromatic aldehydes
Authors: Yale Harry L. , Petigara Ramesh B. 
Published: April 2009

AbstractThe Claisen‐Schmidt condensation between 1,2‐dihydro‐11‐(trifluoromethyl)‐3H,7H‐quino‐[8,1 ‐cd][1,5]benzoxazepin‐3‐one, 1, and aromatic aldehydes has been investigated. The acid catalyzed reactions yielded the trans‐2‐benzylidene derivatives, 4; the structures and configurations of the group of compounds represented by 4 have been confirmed by pmr in conjunction with the Eu(fod)3 shift reagent. In contrast, catalysis with sodium hydroxide gave the isomeric 2‐benzyl‐endocyclic α,β‐unsaturated ketones, 3. Finally, the 4 could be isomerized to the corresponding 3 by means of sodium hydroxide. The ir, uv, and pmr spectra of these compounds are discussed.
New 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinones and 1,2,3,4‐tetrahydro derivatives
Authors: Wan Yieh‐Ping , Porter Thomas H. , Folkers Karl 
Published: April 2009

AbstractThe syntheses of six new 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinones, three 1,2,3,4‐tetrahydro‐5,8‐quinolinequinones, and 7‐(2′,6′,10′‐trimethylundecyl)‐6‐hydroxy‐5,8‐quinolinequinone are described as potential antimetabolites of coenzyme Q and as potential antimalarial agents. The six 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinones were prepared by a six‐step synthesis. 2‐Methyl‐6‐methoxy‐8‐nitroquinoline was prepared from 2‐nitro‐4‐methoxyaniline and crotonaldehyde by a Skraup reaction. Raney nickel reduction gave 2‐methyl‐6‐metboxy‐8‐aminoquinoline, which upon diazotization followed by dithionite reduction yielded 2‐methyl‐6‐methoxy‐5,8‐diaminoquinoline. Subsequent dichromate oxidation gave 2‐methyl‐6‐methoxy‐5,8‐quinolinequinone, which yielded the corresponding 2‐methyl‐6‐alkylamino‐5,8‐quinolinequinone in good yield when treated with the appropriate alkylamine. The telrahydro‐5,8‐quinolinequinones were prepared by catalytic hydrogenation of the appropriate 5,8‐quinolinequinones at elevated H2 pressure followed by air oxidation of the reduction product. 7‐(2′,6′,10′‐Trimethylundecyl)‐6‐hydroxy‐5,8‐quinolinequinone was synthesized by radical alkylation of 6‐hydroxy‐5,8‐quinolinequinone by thermal decomposition of di‐3,7,11‐trimethyldodecanoyl peroxide, which was prepared by a multistep procedure from farnesol. Of the five new 2‐methyl‐6‐alkylamino‐5,8‐quinoline‐quinones tested against P. berghei in mice (blood schizonticidal test), only 2‐methyl‐6‐cycloheptylamino‐5,8‐quinolinequinone was active (T‐C = 6.1 at 320 mg./kg.). Both 7‐(2′,6′,10′‐trimelhytundecyl)‐6‐hydroxy‐5,8‐quinolinequinone and the tetrahydro derivatives were inactive in this same test system.
Heterocycles. CII. Barriers to rotation in some N′‐Heteroaryl N,N‐dimethylformamidines
Authors: Zupan M. , Pirc V. , Pollak A. , Stanovnik B. , Tišer M. 
Published: April 2009

AbstractThe free energies of activation about the =CHNMe2 bond in N′‐heteroaryl N,N‐dimethylformamidines have been found in the range from 15.6 kcal/mole to 23 kcal/mole.