bluuebunny/crossref_metadata_2025_split huggingface dataset:
Astrocyte control of the cerebrovasculature
Authors: Gordon Grant R. J. , Mulligan Sean J. , MacVicar Brian A. 
Published: July 2007

AbstractThe control of cerebral vessel diameter is of fundamental importance in maintaining healthy brain function because it is critical to match cerebral blood flow (CBF) to the metabolic demand of active neurons. Recent studies have shown that astrocytes are critical players in the regulation of cerebral blood vessel diameter and that there are several molecular pathways through which astrocytes can elicit these changes. Increased intracellular Ca2+ in astrocytes has demonstrated a dichotomy in vasomotor responses by causing the constriction as well as the dilation of neighboring blood vessels. The production of arachidonic acid (AA) in astrocytes by Ca2+ sensitive phospholipase A2 (PLA2) has been shown to be common to both constriction and dilation mechanisms. Constriction results from the conversion of AA to 20‐hydroxyeicosatetraenoic acid (20‐HETE) and dilation from the production of prostaglandin E2 (PGE2) or epoxyeicosatrienoic acid (EET) and the level of nitric oxide (NO) appears to dictate which of these two pathways is recruited. In addition the activation of Ca2+ activated K+ channels in astrocyte endfeet and the efflux of K+ has also been suggested to modify vascular tone by hyperpolarization and relaxation of smooth muscle cells (SMCs). The wide range of putative pathways indicates that more work is needed to clarify the contributions of astrocytes to vascular dynamics under different cellular conditions. Nonetheless it is clear that astrocytes are important albeit complicated regulators of CBF. © 2007 Wiley‐Liss, Inc.
Increase in nuclease resistance and incorporation of NF‐κB decoy oligodeoxynucleotides by modification of the 3′‐terminus
Authors: Osako Mariana Kiomy , Tomita Naruya , Nakagami Hironori , Kunugiza Yasuo , Yoshino Masafumi , Yuyama Kazuhiko , Tomita Tetsuya , Yoshikawa Hideki , Ogihara Toshio , Morishita Ryuichi 
Published: July 2007

AbstractBackgroundFor the development of molecular therapy based on oligodeoxynucleotides (ODN), ODN have to be stable against nucleases and be specific to the target transcription factor. To decrease non‐specific binding and degradation from the 3′‐terminus of ODN, we designed partially annealed ODN by binding the extremities of two single strands, resulting in a ribbon‐shaped ODN, so called ribbon‐type decoy ODN (R‐ODN).MethodsWe evaluated the efficiency in the process of enzymatic ligation of R‐ODN, the binding activity to nuclear factor‐κB (NF‐κB), and the stability against Exonuclease III and nucleases present in serum. The functional activity of R‐ODN to inhibit NF‐κBin vitrowas evaluated in human aortic smooth muscle cells (VSMC): TNF‐α‐induced proliferation rate and MMP‐9 expression were assessed after R‐ODN transfection.Results and conclusionsAlthough R‐ODN have a phosphodiester backbone, their physical conformation was designed to provide nuclease resistance without interfering with their binding activity. As expected, R‐ODN showed more resistance to exonucleases and stability in 100% serum than non‐modified decoy ODN (N‐ODN). Importantly, the R‐ODN construction did not interfere with its binding activity to NF‐κB, similar to N‐ODN. Transfection of R‐ODN significantly inhibited the expression of MMP‐9 induced by TNF‐α in VSMC as assessed by real‐time polymerase chain reaction (PCR), and R‐ODN also inhibited the proliferation of VSMC induced by TNF‐α (10 ng/ml), similar to phosphorothioate decoy ODN. Overall, the development of ribbon NF‐κB decoy ODN could provide a useful tool for basic and clinical research. Copyright © 2007 John Wiley & Sons, Ltd.
Pseudosugars, 34. Synthesis of 5a‐carba‐β‐D‐glycosylceramide analogs linked by imino, ether and sulfide bridges
Authors: Tsunoda Hidetoshi , Ogawa Seiichiro 
Published: July 2007

AbstractCarbocyclic analogs of glycoceramides, (2S,3R,4E)‐1‐(5a‐carba‐β‐D‐glycopyranosyl)‐2‐(hexadecanoylamino)‐4‐octa‐decen‐3‐ols E‐3‐E‐6, linked by imino, ether and sulfide bridges, were synthesized by coupling of aziridines, as the sphingosine precursors, with protected 1‐amino, 1‐hydroxy and 1‐mercapto derivatives of 5a‐carba sugars and subsequent deprotection and N‐acylation. Biological assay of 5a‐carbaglycosylceramides showed that both imino‐linked E‐3 and E‐4 having gluco and galacto configurations are mild immunomodulators and possess a mild inhibitory activity against gluco‐ and galactocerebrosidases. These findings prompted us to prepare the corresponding Z‐isomers Z‐3 and Z‐4, which interestingly show a similar enzyme‐inhibitory activity.
Sannamycin‐type aminoglycoside antibiotics of natural and non‐natural (mirror‐image) configuration — total syntheses and biological activity
Authors: Ludin Christian , Weller Thomas , Seitz Bernhard , Meier Walter , Erbeck Silke , Hoenke Christoph , Krieger Richard , Keller Manfred , Knothe Lothar , Pelz Klaus , Wittmer Annette , Prinzbach Horst 
Published: July 2007

AbstractSets of variously protected purpurosamine/2‐epi‐purpurosamine‐type glycosyl donors (O‐acetates) and sannamine‐type glycosyl acceptors were coupled as racemates and pure enantiomers, according to a modified Koenigs‐Knorr procedure with TMSOTf as promotor. The α anomers isolated from the respective mixtures of glycosides (yields varying between 51% and 91%, α:β anomeric ratios between 1.5:1 and 13:1, α:α′ diastereomeric ratios between 1:1 and 1:1.5) were transformed through standard protection/deprotection and glycidation measures into 6′‐des(N‐methyl)sannamycins A (1, 1′, 2, 2′) and B (37, 37′), 2′‐epi‐6′‐des(N‐methyl)sannamycins (3, 3′), the enantiomeric sannamycins A and B (ent‐4)/ (ent‐40), the diastereomers (ent‐4′)/(ent‐40′), and the enantiomeric 2′‐epi‐sannamycin A (ent‐5)/(ent‐β‐5). For one of the fluorinated glycosides (α‐26′), featuring a somewhat unusual aglycon conformation, an X‐ray structural analysis was performed. In explorative biological tests, the naturally configurated glycosides1and3showed limited,2a rather broad activity against a number of pathogenic microorganisms. Yet, none of the glycosides with non‐natural configuration was found to be active.
Chiral polymethine dyes, IV. Synthesis, absolute configuration, spectroscopic and chiroptical properties of chiral tri‐ and pentamethinium cyanine dyes with 1,2,3,4‐tetrahydro‐6‐methylquinolyl end groups
Authors: Reichardt Christian , Harms Klaus , Kinzel Manuela , Schäfer Gerhard , Stein Jörg , Wočadlo Sigrid 
Published: July 2007

AbstractWe have repeated and significantly improved the syntheses of the symmetrical tri‐ and pentamethinium cyanine dyes 10 and 11 in their monochiral forms (10a, b; 11a, b) and in the meso form (11d) as well as of the unsymmetrical monochiral pentamethinium cyanine dye 14a, first realized by König and Langbein in 1928. Their spectroscopic properties have been studied for the first time. The monochiral starting compounds 4a, b, and hence all related monochiral polymethine dyes, have been obtained with high enantiomeric excess (e.e. >99%) by recrystallization of their diastereomeric 3‐bromocamphor‐8‐sulfonates 6a, b. The absolute configuration of 4a, b, and thus the absolute configuration of all monochiral polymethine dyes derived from 4a, b, has been determined by X‐ray structural analyses of the tetrahydroquinolinium perchlorate 7a and the pentamethinium bromide 11a. Partial hydrolysis of the monochiral pentamethinium dye 11a gave the monochiral pentamethine merocyanine dye 12a, which was allowed to react either with 13 to yield the unsymmetrical monochiral pentamethinium dye 14a or with monochiral 7b to afford the symmetrical achiral meso‐pentamethinium dye 11d. The pentamethinium cyanine dyes 11a, b, d and 14a were used to examine the proposed additivity in calculating the overall molecular optical rotation of 11a, b (Table 1).
Phosphanalkylene, 54. Synthese und Eigenschaften von Bis(trimethylsilyl)keton
Authors: Bestmann Hans Jürgen , Haas Wolfgang , Witzgall Konrad , Ricci Alfredo , Lazzari Dario , Degl'Innocenti Alessandro , Seconi Giancarlo , Dembech Pasquale 
Published: July 2007

Phosphane Alkylenes, 54, – Synthesis and Properties of Bis(trimethylsilyl) KetoneThe synthesis of the bis(trimethylsilyl) ketone (1b) by oxydation of [bis(trimethylsilyl)methylene]triphenylphosphorane (3) is described. The IR, UV, NMR, and PE spectra as well as the cyclovoltagram of this compound are discussed and compared with those of di‐tert‐butyl ketone (13) and tert‐butyl‐trimethylsilyl ketone (10).
Electrophile‐induced cyclizations of silyl‐substituted 4‐alken‐1‐ols
Authors: Adiwidjaja Gunadi , Flörke H. , Kirschning A. , Schauman Ernst 
Published: July 2007

AbstractSilyl‐substituted 4‐alken‐1‐ols cyclize in the presence of a wide range of electrophilic reagents to give substituted tetra‐hydrofurans. The silyl group accelerates ring closure by its β‐effect and its position determines the efficiency of stereo‐control. Thus, a vinylic silyl group as in 1, 3‐9 gives mixtures of 2,5‐disubstituted tetrahydrofurans 2, 10‐21, favoring formation of the trans isomer. In contrast, an allylic silyl group as in 28‐30 exerts a high degree of stereocontrol, generally affording 2,3‐trans‐disubstituted tetrahydrofurans 31‐36.
Synthesis of bridgehead polycyclic 1,2‐diamines and 2‐amino alcohol derivatives as Rigid acetylcholine analogs
Authors: Camps Pelayo , Font‐Bardia Mercè , Muñoz‐Torrero Diego , Solans Xavier 
Published: July 2007

AbstractOxidation of dioxime 2a with NBS gave 3 and 4. A chair‐boat conformation has been established for 3 by X‐ray diffraction analysis, while 4 seems to exist in a chair‐chair conformation on the basis of NMR data. m‐Chloroperbenzoic acid oxidation of dioximes 2 gave polycyclic dinitro compounds 7. In some oxidations of 2a, nitroso dimer 8 was isolated, its structure being established by X‐ray diffraction analysis. Reduction of 7 with aluminium amalgam gave in good yields diamines 6, that were also obtained by reductive coupling from dioximes 2. Amino alcohols 14 were obtained by reductive coupling from monooximes 11. While 11a could be obtained in pure form from diketone 1a via 9a and 10a; hydrolysis of 10b to 11b failed. Azapolycyclic compounds 12 were obtained by hydrolysis of 10. Amino alcohol 14b was more appropriately prepared by reduction of nitro alcohol 15 obtained together with 7b by m‐chloroperbenzoic acid oxidation of a mixture containing monooxime 11b and dioxime 2b. From the oxidation of a mixture containing 11a, nitro ketone 16 was isolated in low yield. Amino alcohols 14 and diamines 6 were also characterized as cyclic carbamates 13 or ureas 5. Rigid analogs of acetylcholine 20 and 21 were obtained from 14 by standard procedures, compounds 17 and 18 being detected as intermediates. Neither muscarinic nor antiacetyl‐cholinesterase activity has been observed for compounds 20 and 21.
Synthese und Konformation von Hexahydro‐isochino[3,2‐a][2]benzazepinen des B‐Homoberbin‐Typs
Authors: Meise Werner , Zlotos Darius , Jansen Martin , Zoche Nicola 
Published: July 2007

Synthesis and Conformation of Hexahydro‐isoquino[3,2‐a][2]benzazepines of the B‐Homoberbine TypeThe two‐step synthesis of the hexahydro‐isoquino[3,2‐a][2]‐benzazepines („B‐homoberbines”︁) 4b‐e is described. The main and some further products of the Bischler‐Napieralski reaction of hydroxyamide 3c were isolated and identified. The conformation of the B‐homoberbines was investigated by X‐ray analysis, spectroscopic methods and dehydrogenation with mercury(II) acetate.
Maravuic acid, a new seco‐labdane diterpene from Croton matourensis
Authors: Schneider Christiane , Breitmaier Eberhard , de C. Bayma Joaquim , de Franca Luiz F. , Kneifel Helmut , Krebs Hans‐Christoph 
Published: July 2007

AbstractA new seco‐labdane diterpene, maravuic acid, has been isolated by supercritical fluid extraction using CO2 from the bark of Croton matourensis Aubl. (Euphorbiaceae). Its structure was elucidated by one and two dimensional NMR methods as (12E)‐3,4‐seco‐labda‐4(18),8(20),12,14‐tetraen‐3‐oic acid 2.
Syntheses and structures of 3,7‐substituted barbaralanes
Authors: Quast Helmut , Witzel Martina , Peters Eva‐Maria , Peters Karl , von Schnering Hans Georg 
Published: July 2007

AbstractShort and efficient syntheses of the barbaralanes 2e‐h are reported. Meerwein's diketone 9 is converted into the bis(vinyl sulphide) 10 by the action of 4‐chlorothiophenol in the presence of titanium(IV) chloride and triethylamine. Oxidation of 10 with sodium perborate in acetic acid affords the bis(vinyl sulphone) 11 which is treated with potassium cyanide supported on aluminium oxide to yield the unsaturated dinitrile 8. Bromination of 8 with N‐bromosuccinimide and subsequent reductive cyclisation of the resulting exo,exo dibromodinitrile 13 with the zinc‐copper couple furnish 3,7‐dicyanobarbaralane (2e) in 53% overall yield based on 9. – Treatment of dinitrile 8 with hydrochloric acid in boiling methanol followed by hydrolysis of the intermediate Pinner salt yields the dimethyl dicarboxylate 14 which is brominated to afford the exo,exo dibromo diester 15. Reductive cyclisation of 15 gives rise to the formation of dimethyl 3,7‐barbaralanedicarboxylate (2f) in 49% overall yield based on 9. – Bicyclo[3.3.1]nonane‐3,7‐dione (7) is converted into a mixture of the bis(vinyl sulphones) C2‐ and Cs‐17 (1:1) as described for 9 → 11. Bromination of this mixture yields a single exo,exo dibromo compound 18 which is cyclised by the zinccopper couple to afford 3,7‐bis(phenylsulphonyl)barbaralane (2g) in 56% overall yield based on 7. – The known phenyl‐2‐oxaadamantanol 21a is cleaved by the action of boron trifluoride and acetic anhydride to yield the bicyclo[3.3.1]none‐none 22. The difluoroboron complex 23 is obtained under more rigorous conditions. Addition of phenylcerium(III) chloride to 22 followed by dehydration of the endo alcohol 24 yields the diphenyldiene 25. Bromination of 25 and subsequent reductive cyclisation of the exo,exo dibromodiphenyldiene 26 furnish 3,7‐diphenylbarbaralane (2h) which is isolated by preparative reversed‐phase chromatography in 50% overall yield based on 7. – The configurations and conformations in the crystals are elucidated by X‐ray diffraction analyses for the bicyclo[3.3.1]nonane derivatives 7, 13, 15, 18, 22–24, and 26 and the barbaralanes 2e‐g. In the solid state, 2e and f exist as pairs of rapidly rearranging nonequivalent valence tautomers while the atomic distances observed for 2g indicate the presence of a single nonrearranging valence tautomer.
Antibiotics from gliding bacteria, LXV. Synthesis of soraphen analogues by substitution of the phenyl‐C‐17 ring segment of soraphen A1α
Authors: Schummer Dietmar , Jahn Thorsten , Höfle Gerhard 
Published: July 2007

AbstractThe partial synthesis of 11 analogues of soraphen A1α (1) is described. Reductive lactone ring cleavage, transformation into (17R,S)‐soraphenic acid 10 and cyclization provided unnatural 17‐epi‐soraphen A1α (12). Removal of the phenyl‐C‐17 ring segment of 1 by cleavage of the lactone moiety and the C‐16/C‐17 bond gave the aldehyde 16 as central intermediate. After homologation of 16, introduction of a new C‐17 substituent R or H, and cyclization of the lactone ring, the soraphen analogues butyl‐, thienyl‐, and tolylsoraphen 2b, d, e and 22b, d, e and the desphenylsoraphen 2a were obtained. The ring‐contracted soraphen analogues norsoraphen 29 and 30 and desphenylnorsoraphen 31 were synthesized by introduction of a phenyl group or reduction of the intermediate aldehyde 23 followed by cyclization to the lactone. The biological activity of the soraphen analogues against Candida albicans was determined. Compared to the natural product, all analogues exhibit reduced activity. The activity of the analogues strongly depends upon the nature of the substituent R, the configuration at C‐17, and the ring size.
Halogenated indocyanines: Synthesis, conformational behavior, and light absorption
Authors: Grahn Walter , Johannes Hans‐Hermann , Rheinheimer Joachim , Knieriem Burkhard , Würthwein Ernst‐Ulrich 
Published: July 2007

AbstractThe reactions of the indocyanine 1a and its corresponding 1,3‐diaminoallene 2a with N‐halodiorganosulfonimides 3 or molecular halogen result in the formation of the four chain‐halogenated monomethine cyanines 5a‐d. With an excess of the halogenating agent not only the chain but also the end groups are halogenated affording the monomethines 6 and 7. The preferred conformations, UV/Vis absorptions, and electron densities of the cyanines were calculated by AM1 and PPP methods and experimentally investigated using NMR (DNMR, NOE) as well as UV/Vis spectroscopy.
Marine bacteria, VIII. Maremycin A and B, new diketopiperazines from a marine Streptomyces sp.
Authors: Balk‐Bindseil Wiebke , Helmke Elisabeth , Weyland Horst , Laatsch Hartmut 
Published: July 2007

AbstractIn the culture broth of the marine Streptomyces sp. B 9173 the two novel diketopiperazines maremycin A (1) and B (2) were detected by chemical screening. Their structures were elucidated and confirmed by the synthesis of the oxindole derivative 4.
Spiro units as building blocks in thermotropic liquid crystals: Synthesis and physical properties of terminally substituted spiro[5.5]undecanes
Authors: Schmidt Wolfgang , Vögtle Fritz , Poetsch Eike 
Published: July 2007

AbstractA number of terminally substituted spiranes were prepared from 9‐pentyl‐3‐spiro[5.5]undecanone (7), which was obtained in a five‐step synthesis starting from 4‐pentylcyclohexanone (1), using an intramolecular cyclisation with 4‐toluenesulfonylmethyl isocyanide (TosMIC) as a key step. By a comparison of the physical data of the new spiro[5.5]undecane derivatives I with those of several well‐known, analogous substituted compounds – solely differing in their central building unit – conclusions regarding the effects of the spiro ring system on its mesogenic potential are drawn.
Synthesis of some naturally occurring drimane and dinorlabdane derivatives
Authors: Weyerstahl Peter , Schwieger Ralf , Schwope Ina , Hashem Md. Abul 
Published: July 2007

AbstractThe naturally occurring (ex Hedychium acuminatum) compounds drim‐8(12)‐ene (1), albicanal (4), (E)‐15,16‐dinorlabda‐8(17), 11‐dien‐13‐one (5), and (E)‐15, 16‐dinorlabda‐8(17), 12‐dien‐14‐al (9), were prepared as racemates by starting from the synthetically available rac‐albicanol (2). – The Nozaki reaction of the trimethyldecalone 10 yields 11‐nordrim‐8‐en‐12‐al (11) and its Δ7 regioisomer 12.
Tetra(2,6‐dichlorophenyl)porphyrin — a superior sensitiser for the singlet‐oxygen ene reaction (Schenck reaction)
Authors: Quast Helmut , Dietz Thomas , Witzel Alexander 
Published: July 2007

AbstractThe very useful singlet‐oxygen ene reaction of reluctant alkenes, e.g.1, 5, 7, 8, and, in particular, the mono(allyl hydroperoxides)10and11, is handicapped by the instability of the sensitiser TPP. A comparative study of TPP, TPFPP, and TDCPP in the singlet‐oxygen ene reaction of these alkenes shows that 1) the persistence increases in the order TPP < TPFPP < TDCPP, rendering TDCPP the sensitiser of choice for the generation of singlet‐oxygen in non‐polar solvents, 2) the persistence of the tetraarylporphyrins decreases in the presence of an alkene, 3) this decrease strongly depends on the nature of the alkene, being most pronounced in the case of cyclohexene. These results are interpreted in terms of unknown substrate‐derived species which induce oxidative destruction of the tetraarylporphyrins. Alternatively, abstraction of allylic hydrogen atoms from the alkenes by the excited sensitisers may give rise to the observed substrate‐dependent photobleaching. – Because the singlet‐oxygen ene reaction is the key step of a 1,2‐carbonyl transposition with concomitant dehydrogenation, the scope and usefulness of this sequence are distinctly improved.
Enzymes in organic synthesis, 25. Lipase‐catalyzed sequential esterification of (±)‐2‐methylbutanedioic anhydride — a biocatalytical access to an enantiomerically pure 1‐monoester of (S)‐2‐methylbutanedioic acid
Authors: Ozegowski Rüdiger , Kunath Annamarie , Schick Hans 
Published: July 2007

AbstractThe preparation of enantiomerically pure 1‐(2‐methylpropyl) 4‐hydrogen (S)‐2‐methylbutanedioate (ent‐3) by an enzyme‐catalyzed sequential esterification of (±)‐2‐methylbutanedioic anhydride (rac‐1) demands two different enzymes. Lipozyme, a lipase from Mucor miehei, was used for the alcoholysis of rac‐1 to a mixture of the isomeric monoesters 2/ent‐2 and 3/ent‐3, whereas Novozym 435, a lipase from Candida antarctica, was required for the enantioselective conversion of a mixture of 3 and ent‐3 into the easily separable neutral diester 4 and the acidic monoester ent‐3, which thus was obtained in a yield of 26% with an enantiomeric excess of 99%. ent‐3 was reduced by LiBH4 to (S)‐3‐methylbutan‐4‐olide (ent‐10), a versatile chiral intermediate.
Ethyl N‐(diphenylmethylene)glycinate as anionic glycine equivalent transition metal mediated preparation of bicyclic and tricyclic α,α‐disubstituted α‐amino acids and derivatives
Authors: Moreno‐Mañas Marcial , Pleixats Roser , Roglans Anna 
Published: July 2007

AbstractSynthetic approaches to bicyclic and tricyclic α,α‐disubstituted α‐amino acids and derivatives 6, 8, 10, 12, 13, 21, 22, 23, 24, 28, 30, and 31 are presented. Methyl acetoacetate, ethyl nitroacetate, and ethyl N‐(diphenylmethylene)glycinate are compared as anionic glycine equivalents. Palladium‐induced reductive couplings, Diels‐Alder and Pauson‐Khand reactions are used in the cyclisation steps.
Electron‐transfer‐catalyzed reactions, 7. Aminium salt‐initiated oxygenation of ketenes — formation of succinic anhydrides
Authors: Schmittel Michael , von Seggern Heinke 
Published: July 2007

AbstractThe aminium salt‐initiated oxygenation of ketenes 1a and 1b with molecular oxygen afforded in an unprecedented reaction mode the succinic anhydrides 2 and 3 within a few minutes at 0°C. From mechanistic investigations it is inferred, that the regioselective 1,3‐dipolar cycloaddition of an intermediate α‐lactone, independently trapped by cycloaddition to hexafluoroacetone, to the ketene constitutes the final step of the reaction sequence. Surprisingly, the oxygenation reaction occurred even when the reaction was carried out with rigorous exclusion of atmospheric oxygen. Evidence is presented that aminium salts are capable of both storing and activating molecular oxygen with remarkable efficiency, and that the reaction does not proceed via free ketene cation radicals.
Structure‐odor correlation, XXI. Olfactory properties and convenient synthesis of furans and thiophenes related to rose furan and perillene and their isomers
Authors: Weyerstahl Peter , Schenk Anja , Marschall Helga 
Published: July 2007

AbstractStarting from 3‐bromofuran (1) or 3‐bromothiophene (2) via alkylation in 2‐position (→ 3–8) followed by the corresponding second alkylation in 3‐position, we obtained rose furan (9), rose thiophene (10), and their analogs 11–16. From the α,β‐unsaturated esters 17–20 by hydrogenation (→ 21–24), DIBAH reduction (→ 25–28), and Wittig reaction, perillene (29), thioperillene (30), and their analogs 29–36 were obtained. Olfactory evaluation showed that the difference between the furans and thiophene derivatives is remarkably small, particularly for perillene (29) compared with thioperillene (30), and their analogs. Also the influence of position and structure of the side chain is lower than expected within the compared compounds 9–36.
Synthesis of 5,8‐dimethoxy‐2(1H)‐quinolinones by intramolecular Wittig reaction
Authors: Ferrer Pedro , Avendaño Carmen , Söllhuber Mónica 
Published: July 2007

AbstractThe title compounds 12, which are key intermediates for antitumoral diazaquinomycin A analogues, are obtained by intramolecular Wittig reaction of 1‐[3′,6′‐dimethoxy‐2′‐(α‐oxoacylamino)phenyl]alkyltriphenylphosphonium salts 11, which are prepared via lithiation of 2′,5′‐dimethoxy‐N‐pivaloylaniline 6. The applicability of this route to polysubstituted 2(1H)‐quinolinones 12 and 17 is examined.