bluuebunny/crossref_metadata_2025 huggingface dataset:
1‐Cycloundecen‐3‐in
Authors: Bissinger Hans‐Joachim , Detert Heiner , Meier Herbert
Published: July 2007

Es wird ein Syntheseweg für (E)‐1‐Cycloundecen‐3‐in (E‐5) beschrieben (Schema 2). Die extrem gespannte Verbindung isomerisiert sich bei Raumtemperatur mit einer Halbwertszeit von 2.2 h (ΔG≠ = 76 kJ/mol). Durch Rotation um die CC‐Doppelbindung entsteht dabei (Z)‐1‐Cycloundecen‐3‐in (Z‐5), das keine geometrische Ringspannung Eg mehr besitzt.
Determination of the absolute configuration of α‐aminoalkylphosphonic acids from their CD in the presence of [Ru2(O2CC3H7)4]⊕ Cl⊖
Authors: Frelek Jadwiga , Majer‐Decker Zsuzsa , Snatzke Günther
Published: July 2007

(R)‐1‐Aminoalkylphosphonic acids show in acetonitrile/water (4:1) in the presence of the title complex intense Cotton effects around 590 (positive) and 470 nm (negative) as well as a third weaker one around 320 nm (negative).
Bacteriochlorophyll f. – Partialsynthese und Eigenschaften einiger Derivate
Authors: Risch Nikolaus , Köster Bettina , Schormann Anette , Siemens Thomas , Brockmann Hans
Published: July 2007

Wir beschreiben die Partialsynthese des Bacteriophäophorbid‐f‐methylesters 7 ausgehend vom Chlorophyll‐a/b‐Gemisch 5/6 aus grünen Pflanzen. 7 ist ein Derivat des von uns postulierten, in der Natur jedoch noch nicht entdeckten Bacteriochlorophylls f (4). Verfahren zur Epimerentrennung von 7 werden beschrieben.
Naturally occurring thienyl‐substituted spiroacetal enol ethers from Artemisia ludoviciana
Authors: Hofer Otmar , Wallnöfer Bruno , Widhalm Michael , Greger Harald
Published: July 2007

In addition to the already known 2‐(2‐thienylmethylene)‐1,6‐dioxaspiro[4.5]dec‐3‐ene (1), a hitherto unknown thienyl‐substituted spiroacetal enol ether was isolated from the subterranean parts of Artemisia ludoviciana, the structure of which was elucidated as the dimeric derivative 2. Compound 2 is characterized by a hydroxybutyl side chain (instead of the oxane ring of the spiro system) and a direct link between the thienyl ring of one moiety with the oxolene ring of the second moiety. Optical resolution on triacetyl cellulose revealed that 1 is a racemate and that 2 is a diastereomeric mixture of two enantiomeric pairs [(RR), (SS); (RS), (RS)]. These results were confirmed by MS, 1H‐NMR, 1H lanthanide‐induced shifts, and CD.
Biosynthese von Naturstoffen mit einer PC‐Bindung, I. Einbau von D‐[6,6‐D2]Glucose in (2‐Aminoethyl)phosphonsäure in Tetrahymena thermophila
Authors: Hammerschmidt Friedrich
Published: July 2007

Es wird untersucht, ob die Phosphat‐Phosphonat‐Umlagerung als Modellreaktion für die Biosynthese der PC‐Bindung als Alternative zur Umlagerung der Phosphoenolbrenztraubensäure dienen kann. D‐[6,6‐D2]Glucose wurde hergestellt und dem Nährmedium von Tetrahymena thermophila zugefügt. Aus der feuchten Zellmasse wurde durch Hydrolyse mit 6 N HCl und Ionenaustauscherchromatographie (2‐Aminoethyl)phosphonsäure (AEP) (1) gewonnen und in das kristalline 4‐Brombenzamid 26 übergeführt. Der Gehalt an [1,1‐D2]‐AEP beträgt bis zu 43% neben im wesentlichen nichtmarkierter AEP, was mit einer enzymatischen Phosphat‐Phosphonat‐Umlagerung von Dihydroxyacacetonphosphat nicht vereinbar ist, für die monodeuterierte AEP zu erwarten wäre. Für Vergleichszwecke wurde ausgehend vom 2‐Amino‐[1,1‐D2]ethanol durch Umfunktionalisierung [1,1‐D2]‐AEP (31) gewonnen.
Application of trichloroethylene in organic syntheses, IV. Syntheses of 9‐(1,2‐dichlorovinyl)carbazoles
Authors: Pielichowski Jan , Bogdał Dariusz
Published: July 2007

Trichloroethylene reacts stereoselectively with carbazole or its derivatives in the presence of aqueous NaOH and catalytic amounts of benzyltriethylammonium chloride (TEBA) to give high yields (about 80%) of 9‐[(E)‐1,2‐dichlorovinyl] carbazole derivatives 6.
Reaktionen von Chlorpyrimidinen, I Synthese von Thieno[2,3‐d]pyrimidinen und Pyrrolo[2,3,‐d]pyrimidinen
Authors: Ried Walter , Beller Gernfried
Published: July 2007

2‐Chlor‐3,3‐dicyanacrylsäure‐ethylester (1) reagiert mit N,N‐Dialkylcyanamiden 2 zu den Chlorpyrimidinen 4a–e. Mit Thioglycolsäure‐ and Sarkosinderivaten erhält man aus 4 die Thieno‐ bzw. Pyrrolopyrimidine 6a–k. Acetylierung von 6a,e und g führt zu 7a–c und 8a–c, mit Aminen erhält man die Amide 9a–f. Reaktion von 6e,g und 9b,d mit Phenylisocyanat ergibt die Harnstoffe 10a–d, aus denen die Dipyrimidine 11a–d gebildet werden. 12a–d entstehen durch Reaktion von 9 mit Formamid. 6k setzt sich mit Orthoameisensäureester oder salpetriger Säure zu 13a bzw. 13b um.
Synthese von erythro‐Sphingosinen über die Azidoderivate
Authors: Zimmermann Peter , Schmidt Richard R.
Published: July 2007

Aus D‐Galactose und D‐Xylose wurden in zwei Stufen die 2,4‐O‐geschützten D‐Threosen 3a bzw. 3b erhalten, die durch Wittig‐Reaktion in Anwesenheit von überschüssigem Lithiumbromid die Trans‐Entriole 4aA, 4aB und 4bA liefern. Triflat‐Aktivierung der freien 2‐Hydroxygruppe, Azideinführung und Abspaltung der O‐Schutzgruppe führte zu den Azidosphingosinen 6A,B die durch Azidreduktion in die D‐erythro‐Sphingosine 7A,B übergeführt wurden. Für die Glycosphingolipidsynthese durch Azidosphingosin‐Glycosylierung wurden aus Verbindung 6A durch 1‐O‐Tritylierung, 3‐O‐Schutzgruppeneinführung und anschließende 1–O‐Detritylierung die 3‐O‐geschützten Azidosphingosine 11α‐11γ hergestellt.
Pheromone synthesis, CIX. Synthesis of the four stereoisomers of 6,12‐dimethyl‐2‐pentadecanone, the sex pheromone of Diabrotica balteata LeConte
Authors: Mori Kenji , Igarashi Yasuhiro
Published: July 2007

The synthesis of the four stereoisomers of 6,12‐dimethyl‐2‐pentadecanone (1), the sex pheromone of the banded cucumber beetle (Diabrotica balteata LeConte), was achieved employing the enantiomers of citronellol (2) as the starting materials.
Synthesis of pyrimidine analogues of the nucleoside antibiotic ascamycin
Authors: Castro‐Pichel Julia , García‐López M. Teresa , De las Heras Federico G. , Herranz Rosario
Published: July 2007

Four analogues of ascamycin 〈5′‐O‐[N‐(L‐alanyl)sulfamoyl]‐2‐chloroadenosine〉 (1) in which the 2‐chloroadenosine moiety has been replaced by uridine, thymidine, cytidine, and 2′‐deoxy‐5‐methylcytidine have been synthesized by selective aminoacylation of the 5′‐O‐sulfamoyl derivatives 2, 9, 14, and 21 of 2′,3′‐di‐O‐acetyluridine, 3′‐O‐acetylthymidine, 2′,3′‐O‐isopropylidenecytidine, and 3′‐O‐acetyl‐2′‐deoxy‐5‐methylcytidine, respectively, with Boc‐L‐Ala‐OSu in DMF and in the presence of DBU, followed by removal of the protecting groups. Similarly, 5′‐O‐[N‐(D‐alanyl)sulfamoyl]uridine (8) has been prepared from Boc‐D‐Ala‐OSu and 2. Compounds 14 and 21 were directly prepared by sulfamoylation of the 4‐N‐(dimethylamino)methylene derivatives 13 and 20 of 2′,3′‐O‐isopropylidenecytidine and 3′‐O‐acetyl‐2′‐deoxy‐5‐methylcytidine, respectively, via the intermediate 5′‐O‐tributyltin derivatives. Compound 20 was obtained from 5′‐O‐(tert‐butyldimethylsilyl)thymidine (17) by a route involving acetylation, conversion of the thymidine moiety into 5‐methylcytosine through the corresponding triazolylpyrimidinone, and amidine protection.
Enantioselektive Synthese von (−)‐Lycoseron und verwandten Verbindungen
Authors: Kuhnke Joachim , Bohlmann Ferdinand
Published: July 2007

Ausgehend von 4‐Hydroxy‐5‐methylcumarin (1) und (3R,6E)‐(+)‐3,7,11‐Trimethyl‐8,9‐dioxo‐6‐dodecenal (2), das aus (3R)‐(+)‐Citronellal (6) gewonnen wird, erhält man sterisch einheitlich chirales (−)‐Lycoseron (4). Davon ausgehend lassen sich sieben weitere Naturstoffe darstellen, deren Strukturen und absolute Konfigurationen damit endgültig gesichert werden.
Preparative UV‐VIS laser photochemistry: Photocycloadditions of methylenelactones with benzophenone and p‐benzoquinone. Oxygen trapping of paterno‐Büchi triplet 1,4‐diradicals as model reactions for quinghaosu‐type 1,2,4‐trioxanes
Authors: Adam Waldemar , Kliem Ulrike , Lucchini Vittorio
Published: July 2007

The UV‐VIS laser irradiation of 4‐penten‐4‐olide (1) with benzophenone (BP) or with p‐benzoquinone (BQ) under an argon atmosphere afforded the acetal‐type oxetanes 2‐BP and 2‐BQ, respectively. Only for BP was the oxetane regioisomer 3‐BP obtained, actually as major product, while 3‐BQ appears to be photolabile under VIS‐laser photolysis conditions and thus does not accumulate in sufficient amounts for detection. Under an oxygen atmosphere, besides these oxetane products also the 1,2,4‐trioxanes 5‐PB and 5‐BQ, the oxygen trapping products of the intermediary preoxetane triplet diradicals 12, were isolated and fully characterized. These results demonstrate that spirolactone‐type 1,2,4‐trioxanes as quinghaosu analogues are accessible via trapping of Paterno‐Büchi triplet 1,4‐diradicals by molecular oxygen. In the case of diketene as enol‐lactone partner, the Paterno‐Büchi reaction with BQ gave a complex product mixture even under an argon atmosphere, leading to the oxetane 6 as major product, and the spirocyclobutanone 7 and spirobioxetane 8 as minor products. Under an oxygen atmosphere also the spiroacetal 9 was obtained, but no trioxanes (oxygen trapping) could be detected in this VIS‐laser photolysis.
Darstellung von α‐Aminohydrazonen mit Triphenyl(β‐phenylhydrazono)phosphoran
Authors: Gnichtel Horst , Sinell Martin
Published: July 2007

Preparation of α‐Amino Hydrazones with Triphenyl(β‐phenyl‐hydrazono)phosphorane

By reaction of the α‐anilinophenones 1a und 1b with triphenyl (β‐phenylhydrazono)phosphorane, the (Z) hydrazones (Z)‐2 are obtained. However, with phenylhydrazine under proton catalysis, the (E) isomers (E)‐2 are formed.
Constituents of cupuliferae, XII. Minor acylated flavonoids from Quercus cerris L
Authors: Romussi Giovanni , Bignardi Gaetano , Pizza Cosimo
Published: July 2007

From leaves of Quercus cerris L. three acylated flavonoid glycosides have been isolated and identified as 3‐O‐isorhamnetin 6‐O‐galloyl‐β‐D‐glucopyranoside (1), 3‐O‐kaempferol 4‐O‐acetyl‐6‐O‐(p‐coumaroyl)‐β‐D‐glucopyranoside (3), and the already described8) 3‐O‐isorhamnetin 6‐O‐(p‐coumaroyl)‐β‐D‐glucopyranoside (2).
Conversion of polyfunctional nitroalkanes into carbonyl compounds synthesis of the pheromone chalcogran and of key building blocks for the macrolides pyrenophorin and vermiculine
Authors: Zschiesche Ruth , Hafner Thomas , Reißig Hans‐Ulrich
Published: July 2007

Starting from nitroalkane adducts of the general structure 3, several versions of the Nef reaction are performed. The reagent combination H2O2/K2CO3 turned out to be the most useful in liberating the carbonyl group because of toleration of acid‐sensitive functionalities. Other methods provide the acetal 5, diketone 7, γ‐lactones 8 and 9, or the chlorinated nitro compound 13, respectively. Cyclization of the highly functionalized diketone 18 gives cyclopentenone derivative 19. Trifunctional and tetrafunctional intermediates 12 and 17 can be transformed into 20 and 21 by reduction and silylation. These compounds are known or conceivable precursors for the antibiotic macrolides pyrenophorin and vermiculine, respectively. Nitroalkane 22 affords within a few simple steps the aggregation pheromone chalcogran 24. The synthetic paths are discussed with regard to efficiency and flexibility.
Der Phenylacetyl‐(PhAc‐)Rest als enzymatisch ablösbare Schutzgruppe für Peptide und Kohlenhydrate: Selektive Schutzgruppenabspaltungen mit Penicillin‐Acylase
Authors: Waldmann Herbert
Published: July 2007

N‐Phenylacetyl‐(PhAc‐)‐aminosäuren werden mit Aminosäuremethyl‐, ‐benzyl‐, ‐allyl‐ und ‐tert‐butylestern mit Hilfe des modifizierten Carbodiimidverfahrens oder unter Verwendung von EEDQ in guten Ausbeuten zu vollgeschützten Dipeptiden verknüpft. Der PhAc‐Rest ist bei den Abspaltungen der C‐terminalen Schutzgruppen stabil, kann jedoch aus den Peptiden unter nahezu neutralen Bedingungen selektiv mit Penicillin‐Acylase (EC 3.5.1.11) abgelöst werden. Das Enzym hydrolysiert den PhAc‐Rest auch aus der 2‐Position von acetylgeschützter Glucose, der 3‐Position von Di‐O‐isopropylidenglucose und der primären OH‐Gruppe von Di‐O‐isopropyliden‐L‐sorbose. Bei den enzymatischen Abspaltungsreaktionen bleiben die säure‐, basen‐ und reduktionsempfindlichen Funktionen in den Substraten unangetastet.
Restriction of the C6N6 bond rotation of adenosine compounds investigated by 1H‐ and 15N‐NMR spectra
Authors: Uzawa Jun , Anzai Kentaro
Published: July 2007

If the C6N6. bond of an adenosine compound has a partial double bond character as is the case of the 3,5′‐cycloadenosine compound 2, the C6N6 bond rotation is restricted, as is observed by 1H‐ and 15N‐NMR spectra.
Stereoselektive Acetalisierung von 1,1‐ und 1,2‐disubstituierten Diolen als allgemeines Syntheseprinzip für die Enantiomeren der bicyclischen Acetalpheromone endo‐ und exo‐Brevicomin sowie Frontalin
Authors: Wershofen Stefan , Claßen Arnold , Scharf Hans‐Dieter
Published: July 2007

Die Acetalisierung der 1,1‐ und 1,2‐disubstituierten Diole 14–19 mit den Ketobausteinen 20 und 21 wird untersucht. Großen Einfluß auf die Stereochemie der gebildeten Dioxolane 22–27 (Diastereomerengemische) hat das Substitutionsmuster der eingesetzten Diole, wobei die Diastereoselektivität durch die Reaktionstemperatur determiniert wird (bis zu de ≧ 99%). Basierend auf diesen Untersuchungen wird die Synthese der Enantiomeren der Pheromone endo‐ und exo‐Brevicomin (1 bzw. 2) sowie Frontalin (3) beschrieben.
Photochemische Studien, 54. Photodimerisierung von Testosteronpropionat in kristallinem Zustand und Kristallstruktur von Testosteronpropionat
Authors: Reisch Johannes , Ekiz‐Gücer Nurten , Takács MiháLy , Takács MiháLy , Henkel Gerald
Published: July 2007

Photochemical Studies, 54. ‐ Photodimerization of Testosterone Propionate in Solid State and Crystal Structure of Testosterone Propionate

On UV irradiation, testosterone propionate (1) dimerizes in solid state to give 6ζ‐(3‐oxo‐17β‐propionyloxy‐5ζ‐androstan‐4ζ‐yl)‐17β‐propionyloxyandrost‐4‐en‐3‐one (4). As shown by an X‐ray analysis of 1, the structure of the topophotodimerization product 4 is determined by the molecular packing of 1 in the crystal.
Funktionell substituierte Vinyllithium‐Verbindungen, 35. Kurze Synthese von 3‐Desoxy‐D‐manno‐2‐octulosonsäure (KDO)
Authors: Enhsen Alfons , Schmidt Richard R.
Published: July 2007

Aus β‐Chlormilchsäureester werden α‐tert‐Butoxyacrylsäure (4b) und die Amide 4c – 4f hergestellt. Mit sec‐Butyllithium als Base können daraus direkt und in hoher Ausbeute die dilithiierten Spezies 4b‐A – 4f‐A erzeugt werden. Durch Reaktion von 4c‐A – 4e‐A mit 2,3:4,5‐Di‐O‐isopropyliden‐D‐arabinose (11) als Elektrophil werden bevorzugt die D‐manno‐2‐octulosonsäure‐Derivate 12c‐m – 12e‐m gebildet. Aus 12c‐m wird dann in drei einfachen und in hoher Ausbeute verlaufenden Stufen (Ringschluß zum Butenolid, Säure‐katalysierte Schutzgruppenabspaltung und Überführung ins Pyranosid) KDO erhalten. Aus der als Nebenprodukt entstandenen D‐gluco‐Verbindung 12c‐g wird entsprechend D‐gluco‐KDO synthetisiert.
Novel Rigid Seven‐Membered Heterocycles: Oxygen‐Bridged 1,5‐Benzothiazepine and 1,5‐Benzodiazepine Derivatives
Authors: Svêtlík Jan , Hanuš VladimíR , Bella Juraj
Published: July 2007

Cyclocondensation of 4‐(2‐hydroxyphenyl)‐3‐buten‐2‐one (1) with o‐aminothiophenol yields 10‐methyl‐11‐oxa‐2‐thia‐9‐azatetracyclo[8.7.1.03,8.012,17]octadeca‐3,5,7,12,14,16‐hexane (2). Similar reaction with o‐phenylenediamine affords the 11‐oxa‐2,9‐diaza analogue 3. The 2‐hydroxyphenylbutenone 1 and 2‐hydroxychalcone (5) show a different bridging ability.
Synthese von 14,17‐überbrückten 11β‐Arylsteroiden
Authors: Scholz Stefan , Hofmeister Helmut , Neef Günter , Ottow Eckhard , Scheidges Cornelius , Wiechert Rudolf
Published: July 2007

Auf der Suche nach neuen Progesteron‐Antagonisten wurden 14,17‐überbrückte 11β‐Arylsteroide synthetisiert. Schlüsselschritt des Verfahrens war die stereo‐ und regioselektive [4 + 2]‐Cycloaddition elektronenarmer Olefine an steroidale 14,16‐Diene. Die auf diese Weise zugänglichen neuen Strukturen wurden auf Progesteronrezeptor‐Affinität und antigestagene Wirkung geprüft.
Asymmetrische Hetero‐Diels‐Alder‐Reaktionen in wäßriger Lösung unter Verwendung von Aminosäureestern als chiralen Auxiliaren
Authors: Waldmann Herbert
Published: July 2007

(R)‐ und (S)‐Aminosäure‐methylester‐hydrochloride bilden mit Formaldehyd in THF/Wasser‐Gemischen Iminium‐Ionen, die als elektronenarme Dienophile mit Cyclopentadien, 1,3‐Cyclohexadien und Alkyl‐substituierten Butadienen bereits bei 0°C Hetero‐Diels‐Alder‐Reaktionen eingehen. Die Cycloaddukte werden mit hohen Ausbeuten im Multigrammaßstab und mit Diastereomerenverhältnissen (bis zu 93:7) gebildet, die mit anderen chiralen Aminen bisher nicht erreicht werden konnten. Mit Hilfe von NOE‐Experimenten werden die absoluten Konfigurationen der Hauptdiastereomeren zugeordnet. Aus den Phenylglycin‐ und den Serin‐Derivaten können die chiralen Hilfsgruppen mittels hydrogenolytischer Methoden bzw. unter Anwendung der Mitsunobu‐Reaktion abgespalten werden. So ist ( – )‐2‐Azabicyclo[2.2.1]‐heptan in enantiomerenreiner Form zugänglich.
Thion‐ und Dithioester, 47. α,β‐ungesättigte Thion‐ und Dithioester durch Kondensationsreaktionen
Authors: Hartke Klaus , Kunze Olaf
Published: July 2007

Die Kondensation der (Dimethoxyphosphinyl)thionacetate 4 (X = O) und ‐dithioacetate 4 (X = S) mit Aldehyden unter Katalyse von wäßrigem Kaliumcarbonat liefert in einer Horner‐Wittig‐Reaktion die α,β‐ungesättigten Thionester 5a–o und Dithioester 6a, b sowie ihre Diels‐Alder‐Dimeren 7c–e. Mit Aldehyden und dem (Trimethylsilyl)thionacetat 13 sowie dem ‐dithioacetat 18 werden in einer Peterson‐Synthese die Thionester 5c, g, j–m, p–r sowie die Dithioester 6b, f–h erhalten. O,O‐Acetale von Aldehyden und Ketonen reagieren mit dem (Trimethylsilyl)ketendithioacetal 19 unter Tritylperchlorat‐Katalyse in einer Aldoladdition zu den β‐Alkoxy‐dithioestern 22, die sich durch Eliminierung von Alkohol in die α,β‐ungesättigten Dithioester 23 überführen lassen.
Thiazolderivate, VII. Darstellung von Thiazolo[4,5‐d]pyrimidin‐Derivaten
Authors: Wobig Dieter
Published: July 2007

Thiazole Derivatives, VII1). ‐ Synthesis of Thiazolo[4,5‐d]pyrimidine Derivatives

The 2‐alkylthio‐4‐aminothiazoles 1a‐k are converted into thiazolo[4,5‐d]pyrimidines 2a‐f, 3, 5, 7a, and 7b. Compound 1a reacts with formamide to give 2a after two hours at 200°C, but after eight hours at 200°C 3 is the resulting product. Reactions of 1b‐e with formic acid and of 1f with formic acid and water give 2a and 2c‐e, whereas 2b and 2f are obtained from 1b and 1e and acetylacetone. 1f reacts with formamide to yield the expected 5. Heating of 1g, 1h, 1j, and 1k with formamide affords the 2‐aminothiazolo[4,5‐d]pyrimidines 7a and 7b under substitution of the alkylthio by the amino group. 2a and 2b yield with phosphoryl chloride 4a and 4b.
Funktionell substituierte Vinylcarbanionen, 38. C‐Glucoside durch direkte 1‐C‐Lithiierung von 2‐Phenylsulfinyl‐aktiviertem D‐Glucal
Authors: Preuss Rainer , Schmidt Richard R.
Published: July 2007

Die direkte 1‐C‐Lithiierung der bequem erhältlichen 2‐Phenyl‐sulfinyl‐D‐glucale 6h, l liefert reaktive Zwischenstufen, die mit Aldehyden als Elektrophile in hohen Ausbeuten reagieren. Die anschließende Entfernung der Phenylsulfinyl‐Gruppe in den Produkten 7 mit Raney‐Nickel und die diastereospezifische Einführung von Wasserstoff an C‐1 und einer Hydroxy‐Gruppe an C‐2 liefert einen einfachen Zugang zu funktionalisierten C‐β‐D‐Glucopyranosiden 10. Die Strukturen werden an Derivaten mit Hilfe von 1H‐NMR‐Daten gesichert.
5,6‐Diaminocaproic Acid by Bamberger Ring Cleavage of Substituted Imidazoles
Authors: Altman Janina , Wilchek Meir
Published: July 2007

Bamberger ring‐cleavage benzoylation of diethyl [2‐(4‐imidazolyl)ethyl]malonate (2) followed by hydrogenation and hydrolysis leads to 5,6‐diaminocaproic acid (d,l‐δ‐lysine) dihydrochloride 5 which is used for the preparation of a dichloro[(d,l)‐diaminocaproic acid]platinum complex.
Electrophilic Cyclization of Doubly Activated Imines with Lewis Acids and Trialkylsilyl Triflates Synthesis of Pyrrole and Azepine Derivatives
Authors: Tietze Lutz F. , Bratz Matthias
Published: July 2007

The cyclization of the (pentenylimino)malonate 8a gives either the pyrrolidines 11a and 12a or the hexahydro‐1H‐furo[3,4‐b]‐pyrrole 13a as main products depending on the Lewis acid used. The isopropyl ester 8b cyclizes under all reaction conditions preferentially to give the lactone ester 13b. Cyclization of the heptenylimine 9 yields exclusively the epimeric octahydro‐1H‐furo‐[3,4‐b]azepines 17 and 18. The thermodynamically more stable 17 could be obtained in large excess. Saponification and decarboxylation of 17 gives the cyclic nonproteinogenic α‐amino acid derivative 20. The octenylimine 10 could not be cyclized under several conditions tested.
Einfache Synthese von Cβ‐D‐Glucopyranosylaromaten ‐ Synthese des 5,7,4′‐Tri‐O‐methylvitexins
Authors: Frick Wendelin , Schmidt Richard R.
Published: July 2007

Durch Umsetzung der C‐lithiierten Phenol‐ und Flavanonderivate 4a‐, b‐A und 16‐A mit den ringoffenen, O‐Benzyl‐geschützten D‐Glucosen 3 und 11 werden die entsprechenden C‐Glucosylderivate 5a,b, 12 bzw. 19 in guten Ausbeuten erhalten. Hydrogenolytische Debenzylierung in Anwesenheit von Eisessig liefert im Falle elektronenreicher Aromatenteilstrukturen (5a, 19) direkt die thermodynamisch stabilen C‐(β‐D‐Glucopyranosyl)derivate 8a und 20. Rascher verläuft offensichtlich die Bildung der entsprechenden C‐Glucofuranosylderivate. Aus Verbindung 20 wird in zwei Stufen das 5,7,4′‐Tri‐O‐methylvitexin 2 synthetisiert.
Chirale Lactole, IX Vergleichende Untersuchungen zur Reaktivität von Lactolen und α‐Hydroxylactolen
Authors: Noe Christian R. , Knollmüller Max , Jangg Edith , Steinbauer Gerhard
Published: July 2007

Eine Synthese der enantiomerenreinen α‐Hydroxylactole 1a–4a wird beschrieben. Bei gleichzeitiger Anwesenheit eines Lactols und eines α‐Hydroxylactols mit trans‐ständigen Hydroxygruppen im Reaktionsgemisch reagiert letzteres mit beträchtlicher funktioneller Spezifität mit einem Amin, während das Lactol bevorzugt mit einem Alkohol das Acetal bildet. α‐Hydroxylactole mit cis‐ständigen Hydroxygruppen reagieren unter den Versuchsbedingungen praktisch nicht.
Synthese von variierten O‐Glycopeptidsequenzen von Interleukin‐2
Authors: Paulsen Hans , Adermann Knut
Published: July 2007

Es wird eine Serie von Glycopeptiden synthetisiert, die Varianten der Sequenz des N‐Terminus von Interleukin‐2 darstellen. Hierin sind Aminosäuren und Glycosylierungsstellen ausgetauscht, oder es ist eine verstärkte Glycosylierung vorgenommen worden. Die Synthesen werden mit den bewährten glycosylierten Bausteinen von Serin und Threonin 1, 2 und 3 durchgeführt, die einen Peptidaufbau mit dem Schutzgruppenmuster Fmoc/tBu erlauben.
Pilzfarbstoffe, 60 Über Leucomentine, farblose Vorstufen des Atromentins aus dem Samtfußkrempling (Paxillus atrotomentosus)
Authors: Holzapfel Monika , Kilpert Claus , Steglich Wolfgang
Published: July 2007

Atromentin (1) liegt in Fruchtkörpern des Samtfußkremplings hauptsächlich in Form der farblosen Leucomentine 3–5 vor. Die Leucomentine sind Ester des Leukoatromentins mit (2Z,4S,5S)‐4,5‐Epoxy‐2‐hexensäure, deren absolute Konfiguration durch Überführung in (+)‐O‐Acetylosmundalacton (6a) bestimmt werden konnte. Dabei wurde der Mechanismus der säurekatalysierten Abspaltung der Säurereste durch 18O‐Markierung aufgeklärt.
Pilzfarbstoffe, 61 Flavomentine und Spiromentine, neue Terphenylchinon‐Derivate aus Paxillus atrotomentosus und P. panuoides (Boletales)
Authors: Besl Helmut , Bresinsky Andreas , Geigenmüller Georg , Herrmann Rupert , Kilpert Claus , Steglich Wolfgang
Published: July 2007

Die Kremplinge Paxillus atrotomentosus und P. panuoides produzieren in geringen Mengen orangegelbe Flavomentine und violette Spiromentine. Bei den Flavomentinen 1–3 handelt es sich um Ester des Atromentins (6) mit (2Z,4E)‐2,4‐Hexadiensäure oder (2Z,4S,5S)‐4,5‐Epoxy‐2‐hexensäure, außerdem kommt als weitere Verbindung dieses Typs 3‐O‐Acetylatromentin (4) vor. Die Spiromentine 8, 11, 12 und 13 besitzen eine ungewöhnliche Spirostruktur, in der ein 4,5‐Dihydroxy‐1,2‐benzochinon mit einem Lacton acetalartig verknüpft ist. Die spektroskopisch abgeleiteten Strukturen der Farbstoffe konnten durch die Synthese von Modellverbindungen und die biomimetische Überführung von Flavomentin B (2) in die Spiromentine B (11) und C (12) gesichert werden.
Reactions of 4‐(Dicyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one Towards Amines and Phenols
Authors: Metwally Saoud A. M. , El Naggar Galal M. , Younis Mansour I. , El‐Emary Talaat I. , Elnagdi Mohamed Hilmy
Published: July 2007

3‐Methyl‐1‐phenyl‐2‐pyrazoline‐4,5‐dione (3) condenses readily with malononitrile in refluxing ethanol to yield 4‐(dicyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one (4). Compound 4 readily reacts with aliphatic, aromatic, and heterocyclic amines to yield 4‐substituted (aminocyanomethylene)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐ones (8). o‐Substituted arylamines afford also 4‐substituted (arylcyanomethylene)pyrazolones, which readily cyclize to give the 4‐azolylidene pyrazolones 9a–c. Secondary and tertiary amines and activated phenols condense with 4 by hydrogen cyanide elimination to yield compounds 10a–c and 10a, b, respectively.
The First Condensation Product of Malononitrile with Ribose
Authors: Eger Kurt , Storz Timo , Spätling Sabine
Published: July 2007

For the first time the 2‐amino‐3‐furancarbonitrile 1 could be obtained as condensation product of ribose with malononitrile in the presence of zinc chloride.
Glycosyl Imidates, 42 Selectively Protected Lactose and 2‐Azido Lactose, Building Blocks for Glycolipid Synthesis
Authors: Jung Karl‐Heinz , Hoch Monika , Schmidt Richard R.
Published: July 2007

Performing regioselective alkylation at 3′‐OH of benzyl β‐lactoside 1 by the stannylation method we prepared the 3′‐OH‐ and 4′‐OH‐unprotected lactose derivatives 5 and 10 and the 4′‐OH‐unprotected lactose derivative 9 containing a different protecting group at 3′‐OH, suitable for further transformations. These building blocks are valuable glycosyl acceptors in glycolipid synthesis. For the synthesis of glycosyl donors with Gal(β1 → 4)GlcNAc‐structure we used the 2‐azido lactose derivative 19. By regioselective alkylation of 3′‐OH by the stannylation method and application of other common regioselective protecting procedures we prepared the trichloroacetimidates 17, 24, and 30 containing special protecting groups at 3′‐OH, 4′‐OH, and 6′‐OH which are suitable for further transformations in these positions.
Glycosyl Imidates, 43 Synthesis of Lactoneotetraosyl Ceramide
Authors: Bommer René , Schmidt Richard R.
Published: July 2007

Azidosphingosine glycosylation proved to be a valuable method for the synthesis of lactoneotetraosyl ceramide 15. For this aim the 2‐azido‐2‐deoxylactosyl donor 5 was treated with the lactosederived acceptor 4 to provide the tetrasaccharide derivative 6. Transformation into the corresponding trichloroacetimidate 10 led to an efficient tetraosyl donor for the β‐selective glycosylation of 3‐O‐benzoyl‐azidosphingosine 11. The product 12 was converted into the lysoglycosphingolipid 14; palmitoylation of the free amino group then afforded compound 15.
Synthesis of Nonproteinogenic (R)‐ or (S)‐Amino Acids Analogues of Phenylalanine, Isotopically Labelled and Cyclic Amino Acids from tert‐Butyl 2‐(tert‐Butyl)‐3‐methyl‐4‐oxo‐1‐imidazolidinecarboxylate (Boc‐BMI)
Authors: Seebach Dieter , Dziadulewicz Edward , Behrendt Linda , Cantoreggi Sergio , Fitzi Robert
Published: July 2007

The enantiomerically pure glycine derivatives (R)‐ and (S)‐Boc‐BMI, commercially available on a kg scale, are used as starting materials (Scheme 1) for the preparation of (i) open‐chain amino acids such as α‐deuterio amino acids (4, 5), β‐arylalanines (2), aspartic acid derivatives (6, 7a, 8), or ω‐halo amino acids (7b, c, 12, 13, 16, 17, 19, 22), (ii) of α‐aminocycloalkanecarboxylic acids (9, 11), and (iii) of heterocyclic α‐amino acids (14, 15, 18, 20) containing azetidine, pyrrolidine, piperidine or perhydroazepine rings. Inversion by deprotonation / protonation or deuteration allows to prepare either enantiomer of an amino acid from the same Boc‐BMI enantiomer (Scheme 5). Effects of additives such as the cyclic urea DMPU, lithium salts, or secondary amines upon the reactivity of lithium enolates are discussed and, in part, exploited.
Gloeosporone – A Macrolide Fungal Germination Self‐Inhibitor Total Synthesis and Activity
Authors: Seebach Dieter , Adam Geo , Zibuck Regina , Simona Wilhelm , Rouilly Marizel , Meyer Walter L. , Hinton James F. , Privett Thomas A. , Templeton George E. , Heiny Dana K. , Gisi Ulrich , Binder Heinz
Published: July 2007

Starting with (S)‐ or (R)‐4‐Bromo‐1,2‐epoxybutane [commercially available or readily made from (S)‐ or (R)‐malic acid], both enantiomers of the germination self‐inhibitor gloeosporone were synthesized. The absolute configuration of the natural product was thus proven to be 4S,7R,13R. Microbiological studies showed that both enantiomers of the compound cause inhibition of germination in spores of Colletotrichum gloeosporioides, and that (‐)‐gloeosporone is also active against a variety of other fungi. In order to gain some insight into the mode of action, 23Na NMR measurements and ion‐selectivity studies were undertaken; none of these experiments provided evidence for a gloeosporone–metal ion interaction.
Metabolic products of microorganisms, 256. Pyrrolams, new pyrrolizidinones produced by Streptomyces olivaceus
Authors: Grote Ralph , Zeeck Axel , Stümpfel Joachim , Zähner Hans
Published: July 2007

Pyrrolams A to D (1–4), biosynthetically new pyrrolizidinones produced by Streptomyces olivaceus, have been discovered by chemical screening. Their structures have been determined by spectroscopic methods and by a comparison of (R)‐dihydropyrrolam A (5) with a synthetic sample obtained from (S)‐proline. The pyrrolams differ from the necine bases found in plant‐originating pyrrolizidine alkaloids by their less complicated structures.
Isolation and structure determination of new spiro‐bicyclic triterpenoids from Iris pseudacorus
Authors: Marner Franz‐Josef , Littek André , Arold Rainer , Seferiadis Konstantin , Jaenicke Lothar
Published: July 2007

Four novel types of iridals (compounds 8, 9, 15 and 16) have been isolated from lipid extracts of roots and rhizomes of I. pseudacorus and their structures (except the stereochemistry of 15 at C‐13 and C‐26 and of 16 at C‐13) elucidated by oxidative degradation combined with spectroscopic methods. They are up to now unknown triterpenoids with unusual spiro‐bicyclic structures. The possible biogenesis of these compounds is descussed.
A new route to 2′,3′‐dideoxycytidine
Authors: Motawia Mohammed S. , Pedersen Erik B.
Published: July 2007

2‐Deoxy‐D‐ribose (1) was converted into its methyl glycofuranoside 2, which was treated with 4‐biphenylcarbonyl chloride to give a separable mixture of 3 (26%) and 4 (40%). Compounds 3 and 4 were deoxygenated by Barton deoxygenation to give the corresponding 2,3‐dideoxyribose derivatives 7 and 8 in good yields as crystalline materials. Reaction of 7 and 8 with the silylated N4‐isobutyrylcytosine 9, using trimethylsilyl triflate as catalyst afforded a separable mixture of the protected 2′,3′‐dideoxynucleosides 10 (29%) and 11 (31%) which were deprotected with methanolic ammonia to give 2′,3′‐dideoxycytidine (12) and its α‐anomer 13.
Stereoselective synthesis of 2‐azapurine 2′‐deoxy‐β‐D‐ribonucleosides by nucleobase‐anion glycosylation
Authors: Kazimierczuk Zygmunt , Seela Frank
Published: July 2007

Nucleobase‐anion glycosylation of 6‐(methylthio)‐2‐azapurine (1) with 2‐deoxy‐3,5‐di‐O‐(p‐toluoyl)‐α‐D‐erythro‐pentofuranosyl chloride (2) yields the 2′‐deoxy‐β‐D‐ribofuranosides 3–5 stereoselectively. The distribution of regioisomers is as follows: N‐9 (32%); N‐2 (30%), and N‐7 (7%) together with a minor amount of an unidentified labile glycosylation product. The anomeric configuration and the site of glycosylation have been assigned on the basis of the 1H‐NOE difference spectral data in combination with gated‐decoupled 13C‐NMR and selective INEPT spectroscopy. The regioisomeric 6‐methylthio nucleosides have been converted into 6‐substituted derivatives of biological interest including 2′‐deoxy‐2‐azaadenosine (8). Compound 8 is a substrate of adenosine deaminase.
Steroidal cyclobutanones, I. Synthesis and stereochemistry of steroidal spirocyclobutanones
Authors: Paryzek Zdzislaw , Blaszczyk Krzysztof
Published: July 2007

Cycloaddition of dichloroketene to 3‐, 7‐, and 17‐methylene steroids affords the corresponding spirodichlorocyclobutanones, which can be reduced to monochloro‐ and unsubstituted spirocyclobutanones. Selective cycloaddition to the exo‐double bond is observed in the reaction of 3β‐acetoxy‐17‐methylene‐5‐androstene. The stereochemistry of spiro compounds is assigned on the basis of 1H‐ and 13C‐NMR spectra. Some steroidal spirolactones are obtained and their stereochemistry is assigned.
Thermische Diels‐Alder‐Reaktionen mit N‐(2‐Alkenoyl)‐(S)‐prolinestern als chiralen Dienophilen in organischen und wäßrigen Reaktionsmedien
Authors: Waldmann Herbert , Dräger Martin
Published: July 2007

Thermal Diels‐Alder Reactions with N‐(2‐Alkenoyl)‐(S)‐proline Esters as Chiral Dienophiles

Cyclopentadiene reacts with N‐acryloyl‐(S)‐proline benzyl and allyl ester in toluene at 0°C to give the bicycloheptene‐carboxylic acid amides with a stereoselection of (2S):(2R) = 81:19. In the reactions with the N,N′‐fumaroylbis(proline esters) the cycloadducts are formed in high yields and with isomer ratios of up to 97:3. The absolute configuration of N,N′‐〈(1R,2R,3R,4S)‐bicyclo[2.2.1]hept‐5‐ene‐2,3‐diyldicarbonyl〉bis‐[(S)‐proline benzyl ester] (6 a) has been determined by an X‐ray analysis. In the reactions of the acrylamides with cyclopentadiene and of the fumaramides with cyclopentadiene, isoprene and 2,3‐dimethylbutadiene the use of water/ethanol mixtures as solvent, if indicated in the presence of detergents, doubles the yields. However, a positive influence of the aqueous medium on the diastereomeric ratio can not be observed.
Hydroacridine, XIII. Sterischer Verlauf der N‐Oxidation von N‐Alkyl‐Derivaten des (4aα,8aβ,9aβ,10aα)‐Tetradecahydroacridins (α‐Perhydroacridin)
Authors: Potmischil Francisc , Naiman Marian
Published: July 2007

Hydroacridines, XIII. — Steric Course of the N‐Oxidation of N‐Alkyl Derivatives of ((4aα,8aβ,9aβ,10aα)‐Tetradecahydroacridine (α‐Perhydroacridine)

Diese Arbeit wurde auf der 5. rumänischen Konferenz für allgemeine und angewandte physikalische Chemie, Bukarest, 1. −4. September 1976, mitgeteilt.

The oxidation of N‐methyl‐α‐perhydroacridine (1), with hydrogen peroxide at room temperature occurs approximately with 83% by equatorial, and approximately with 17% by axial attack of the oxygen on the nitrogen atom. The oxidations of N‐ethyl‐ (2) and N‐benzyl‐α‐perhydroacridine (3) yield only the N‐oxides with axial oxygen (2′a and 3′a, respectively).
En route to thromboxane compounds from carbohydrates, I. Synthesis of the unsaturated sugar precursors
Authors: Pelyvás István , Lindhorst Thisbe , Thiem Joachim
Published: July 2007

Allyl 4‐C‐[(carboxamido)‐ and (ethoxycarbonyl)methyl]hex‐2‐enopyranosides 18a–c, representing chiral precursors for the carbohydrate‐based construction of the ring systems of thromboxane A2 and B2 were prepared by means of the Claisen‐type rearrangement of the suitably substituted hex‐3‐enopyranosides 7a, b. The latter sugars were synthesized from allyl α‐D‐glucopyraoside (9) by modification of known procedures, including selective O‐benzoylation with 1‐(benzoyloxy)‐1H‐benzotriazole (11), and Tipson‐Cohen sulfonyl ester elimination of the 3,4‐di‐O‐mesylates 16 and 17. Studies on the corresponding methyl glycosides 8a–c showed a reduced stability of the 6‐O‐(tert‐butyldiphenylsilyl) ether group under the Tipson‐Cohen reaction conditions.
Stereoselektive Synthese des substituierten Morphan‐Gerüstes ausgehend von 4‐Acetamidocyclohexanon
Authors: Teuber Hans‐Joachim , Tsaklakidis Christos , Bats Jan Willem
Published: July 2007

Stereoselective Synthesis of the Substituted Morphane Framework Starting with 4‐Acetamidocyclohexanone

4‐Acetamidocyclohexanone (2), prepared from 4‐acetamido‐cyclohexanol (1), has been transformed into the ethyleneacetal 3b which was amidated with pyruvic and 2‐oxobutyric acid to give 3c and d, respectively. After removal of the protecting group (4a, b) the amide is treated with sodium hydride in tetrahydrofuran or with sodium ethylate in ethanol. Depending on the reaction conditions 4b is transformed into the aldol 6 or the cyclised aldol 5b (5a from 4a, respectively) with 2‐azabicyclo[3.3.1]nonane structure and endo‐positioned hydroxy group. Constitution and stereochemistry has been proved by X‐ray structure analysis of 7a. The stereochemistry of the ring closure reaction corresponds to the transition state postulated.
Tetra‐O‐acetyl‐β‐D‐glucopyranosyl chloride: Occurrence of gg and gt rotamers in the crystal and correlation between conformation at C‐6 and anomeric stabilization
Authors: Lichtenthaler Frieder W. , Rönninger Stephan , Kreis Uwe
Published: July 2007

An X‐ray structural analysis of 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl chloride (5β) shows the crystal lattice to contain consecutive layers of two forms, each in the 4C1 conformation, but differing in the orientation of the 6‐acetoxy group relative to the pyranoid ring: the gauche‐gauche (gg) rotamer, exhibiting standard bond lengths and torsional angles, and the gauche‐trans (gt) form, in which an unusually long C‐5—O‐5 bond distance of 1.536 Å is observed, though without major distortion of the chair conformation. In solution, only the gg form prevails. The similarity of conformational features of 5β in its gg form and of its β‐methoxy analog 7β is so close that the anomeric effects for equatorial Cl and OCH3 on a pyranoid ring must be grossly identical. — Force‐field calculations on the anomeric 1‐chloro‐ and 1‐methoxy derivatives of tetra‐acetyl‐D‐glucopyranose allow a realistic estimation of the magnitude of the anomeric effect and a surprisingly accurate assessment of the degree of anomeric stabilization in the individual C‐6 rotameric forms, the gg conformer invariably being the energetically most favored.
Chemoenzymatische „Chiral‐Pool”︁‐Synthese von (+)‐exo‐Brevicomin aus Kohlenhydraten mit Fructose‐1,6‐diphosphat‐Aldolase
Authors: Schultz Michael , Waldmann Herbert , Kunz Horst , Vogt Walter
Published: July 2007

Chemoenzymatic “Chiral‐Pool” Synthesis of (+)‐exo‐Brevicomin from Carbohydrates Using Fructose 1,6‐Diphosphate Aldolase

Fructose‐1,6‐diphosphate aldolase (EC 4.1.2.13) catalyzes the stereospecific aldol reaction between 1,3‐dihydroxyacetone phosphate (4) and 5‐oxohexanal (3) or its 5‐dithiane‐protected analog 8. The products of the aldol reactions are dephosphorylated with acid phosphatase (EC 3.1.3.2). Whereas the aldol adduct of 3 cyclizes spontaneously to give the bicyclic brevicomin precursor 3, the adduct of 8 first has to be deprotected with sulfuryl chloride and wet silica gel. The resulting bicyclic α‐hydroxy ketone 3 is reduced with LiAlH4 to form the 1,2‐diol 14 which is then deoxygenated to give the vinyl compound 17 by treatment of the corresponding dixanthate 15 with tributyltin hydride or by treatment of the corresponding mesylate 16 with sodium naphthalenide. The olefin 17 is finally converted to (+)‐exo‐brevicomin (1) by hydrogenation with diimide.
Structure — Odor correlation, X. Synthesis and olfactive properties of 7‐oxanorbornanes
Authors: Weyerstahl Peter , Brendel Joachim
Published: July 2007

The 7‐oxanorbornanes 17–19 are prepared by Diels‐Alder reaction of 2,5‐dimethylfuran (1) and 2‐isopropyl‐5‐methylfuran (2) with 2‐chloro‐ (3) or 2‐acetoxyacrylonitrile (4). The adducts 5–10a,b are hydrogenated (→ 11–16a, b) and subsequently hydrolyzed. From 1 and acrylonitrile (21) the stereoisomers 25a, b can be obtained via 23a, b in various ratios, depending on the reaction conditions. The Grignard reaction of the exo nitrile 25a with MeMgI or iPrMgI gives the exo ketones 27a and 28a. In the case of the endo nitrile 25b the same reaction favors the formation of side products. LiAlH4 reduction of 17, 26b, 27b, and 28a yields the 7‐oxanorbornanyl alcohols 29b–31b and 32a. — The fragrance of the ketones 18 and 19 is very similar to that of the substructures 1,4‐cineol and menthone. The smell of ketones 27 and 28 as well as of the alcohols 29b–31b is weak. Odor quality and strength of the alcohols 32a′, a″ are determined by their ability to form more or less easily an intramolecular hydrogen bond leading to a rigid conformation which is responsible for the typical minty‐camphoraceous odor.
Darstellung 2‐methoxysubstituierter Pyrrole durch intramolekulare Aza‐Wittig‐Reaktionen
Authors: Montforts Franz‐Peter , Schwartz Ulrich Manfred , Maib Piotr , Mai Gerhard
Published: July 2007

Preparation of 2‐Methoxy‐Substituted Pyrroles by Aza‐Wittig Reactions

α‐Halo ketones and dimethyl malonate can be transformed by Knoevenagel condensation and nucleophilic displacement of halogen with sodium azide into the azide esters 10. These azides undergo ring closure to 2‐methoxy‐substituted pyrroles 11 by intramolecular Aza‐Wittig reaction.
Biologically active glycosides from asteroidea, XXIV. Stereochemistry of the four diastereomers of phytosphingosine
Authors: Sugiyama Shigeo , Honda Masanori , Komori Tetsuya
Published: July 2007

Diastereomeric D‐ribo‐(2S,3S,4R)‐, D‐lyxo‐(2S,3S,4S)‐, D‐arabino‐(2S,3R,4S)‐, and D‐xylo‐(2S,3R,4R)‐C16‐phytosphingosine tetraacetates 2–5 were synthesized from the oxazoline 11 derived from (S)‐serine. Detailed physical data were obtained and the stereochemistry can be readily identified, regardless of any new phytosphingosine moiety of the glucosphingolipids which may be detected in nature.
Preparation of some fully chloroacetylated glycopyranosyl bromides: Useful intermediates for the synthesis of base‐ and hydrogenolysis‐sensitive glycosides
Authors: Ziegler Thomas
Published: July 2007

Chloroacetylation of alkyl glycopyranosides of β‐D‐galactose, β‐D‐glucose and α‐D‐mannose as well as of free D‐glucose, D‐galactose, D‐mannose and D‐xylose, using chloroacetic anhydride as acylating reagent, gave the corresponding fully chloroacetylated pyranose derivatives in excellent yields. From D‐glucose, 1,2,3,6‐tetra‐O‐chloroacetyl‐α‐D‐glucopyranose (9) was also obtained. Subsequent treatment of the fully chloroacetylated α‐D‐glycopyranoses 3, 8, 13 and 15 of galactose, glucose, mannose, and xylose, respectively, with HBr resulted in 2,3,4,6‐tetra‐O‐chloroacetyl‐α‐D‐galactopyranosyl bromide (4, 98%), ‐glucopyranosyl bromide (10, 92%), ‐mannopyranosyl bromide (14, 72%) and 2,3,4‐tri‐O‐chloroacetyl‐α‐D‐xylopyranosyl bromide (16, 68%). 10 reacted with D‐pantholactone (17) and silver trifluoromethanesulfonate under acidic conditions to give the corresponding α‐linked (18, 45%) and β‐linked (20, 38%) glucopyranosides. Under basic conditions the corresponding ortho ester product 21 was formed (92%) which upon treatment with BF3 gave the glucosides 18 and 20. Silver silicate as the catalyst gave only traces of 18. Thus, 20 was isolated in 80% yield. Reaction of 10 with silver crotonate and silver laurate gave 1‐O‐crotonoyl‐ (22) and 1‐O‐lauroyl‐2,3,4,6‐tetra‐O‐chloroacetyl‐β‐D‐glucopyranose (24), respectively. 18 and 22 were dechloroacetylated with thiourea, affording the corresponding deblocked glucose derivatives 19 and 23, respectively.
One‐pot synthesis of polyfunctionally substituted 2,3‐dihydrothiazoles and thiazolidinones
Authors: Mohareb Rafat M. , Sherif Sherif M. , Abdel‐Aal Fatma A. M. , Sayed Nadia I. A.
Published: July 2007

The reaction of phenyl isothiocyanate with the active methylene reagents 1a–e gives the nonisolable 1:1 adducts 2a–e. The latter react with α‐halogenated compounds, e.g. phenacyl bromide, bromoacetyl bromide, chloroacetone, chloroacetonitrile and some hydrazonoyl halides to give the corresponding polyfunctionally substituted 2,3‐dihydrothiazoles or thiazolidinone ring systems.
Neue 21,22‐Dioxaporphyrin‐5(23H)‐one, Sauerstoff‐Analoga der Oxophlorine
Authors: Rusch Roland , Gast Achim , Breitmaier Eberhard
Published: July 2007

New 21,22‐Dioxaporphyrin‐5(23H)‐ones, Oxygen Analogues of Oxophlorins

12,13,17,18‐Tetraalkyl‐21,22‐dioxaporphyrin‐5(23H)‐ones 10 (21,22‐dioxa‐5‐oxophlorins) have been synthesized by MacDonald cyclization from Bis(5‐formyl‐2‐furyl)methanone (4) and 3,3′,4,4′‐tetraalkyl‐2,2′‐dipyrrylmethanes 8 in dichloromethane with acetic anhydride. IR, UV and NMR spectroscopic data have been compared with those of 3,7,13,17‐tetraethyl‐2,8,12,18‐tetramethyl‐21H,23H‐porphyrin‐5(22H)‐one (12) which has also been newly synthesized. NMR shifts did not provide evidence for the diaza[18]annulene tautomers 11 of the 21,22‐dioxaphlorin‐5‐ones 10.
Studies on alkyl‐substituted, heteroaromatic carbonitriles: Novel synthesis of thienoazines and benzoazines
Authors: Elnagdi Mohamed Hilmy , Erian Ayman Wahba
Published: July 2007

The alkyl‐substituted heterocyclic carbonitriles 1–3 react with elemental sulphur to yield the thienoazines 7, 11 and 13, respectively. Whereas 7 reacts with acrylonitrile to afford a [4+2] cycloaddition product with elimination of hydrogen sulphide, compounds 11 and 13 are not converted into cycloadducts. The quinoline 9a and the quinazoline 14 are obtained by reaction of 1 and 3, respectively, with formaldehyde and malononitrile. The thienopyridines 16 are produced by reaction of 6a, c with benzylidinemalonitrile. Furo[3,4‐f]indazole 19 is prepared by [4 + 2] cycloaddition of the thienopyrazole 18 with maleic anhydride. The effect of the substituent of the thienyl moiety of the thienopyridazine ring system on its reactivity toward electron‐poor olefins has been investigated.
P(III)‐Acridinderivate als Synthesebausteine für die Festphasensynthese nichtradioaktiv markierter Oligonucleotide
Authors: Möller Uwe , Cech Dieter , Schubert Frank
Published: July 2007

P(III)‐Acridine Derivatives as Building Blocks for the Solid‐Phase Synthesis of Non‐Radioactively Labelled Oligonucleotides

In contrast to 9‐(2‐hydroxyethyl)‐10‐methylacridinium salts 5 9‐(2‐hydroxyethyl)acridine (2) proved to be a useful intermediate for the synthesis of 2‐(9‐acridinyl)ethyl phosphoramidites 8 or 2‐(9‐acridinyl)ethyl H‐phosphonates 9 suitable for the introduction of acridine into oligonucleotides. The phosphorous compounds 8 and 9 were synthesized by modified standard procedures. The phosphoramidites and H‐phosphonates of 2 are attached to the 5′ end of different oligonucleotides in the last cycle of the solid‐phase synthesis.
The synthesis of 3‐deoxy‐L‐fucose (3,6‐dideoxy‐L‐xylo‐hexose)
Authors: Lindhorst Thisbe K. , Thiem Joachim
Published: July 2007

The synthesis of 3‐deoxy‐L‐fucose (19) could not be achieved by an inversion procedure, starting from the 3‐O‐triflate‐activated derivatives 8 or 9, respectively. Also the Mitsunobu reaction with the 3‐OH‐unblocked sugars 6 or 7 did not lead to the desired compounds. Instead, the formation of the unexpected side products 10, 11 and 12 was observed and interpreted. However, an equilibrium mixture of 3‐deoxy‐L‐fucose 19 and 21 was successfully synthesized by utilizing a Barton‐type deoxygenation of methyl 2,4‐di‐O‐benzoyl‐α‐L‐fucoside (7). The latter compound could be obtained from methyl α‐L‐fucoside (1) in a one‐pot reaction and crystallization in approximately 70% yield.
Novel, diastereoselective synthesis of 3‐amino‐1‐alkanols
Authors: Oszbach György , Neszmélyi András
Published: July 2007

Benzaldehyde adds to 1‐pyrrolidinylcyclohexene under mild conditions giving the amino ketone 3a. The unstable ketone was reduced to the epimeric alcohols 4 and 5, the stereochemistry of which was determined by 2D‐NMR correlation spectroscopy.
Synthesis and biological activities of new analogues of thymopoietin II (32–36)
Authors: Nawrocka‐Bolewska Eleonora , Siemion Ignacy Z. , Mihelić Mirna , Voelter Wolfgang
Published: July 2007

The pentapeptide fragment of thymopoietin II (32–36) (TP5) shows similar biological activities as the parent molecule, also induces E‐rosette formation, and enhances phagocytosis. In order to elucidate further structural and functional requirements for its activity we decided to replace each amino acid residue of the pentapeptide by proline moieties.