bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Novel N‐[2‐(1H‐Azol‐1‐yl)‐1‐arylethylidene]methanamine N‐Oxides
Authors: Mullen George B. , Bennett Grace A. , Swift Patricia A. , Kuipers William J. , Georgiev Vassil S T.
Published: July 2007

The synthesis and configurational purity of a series of novel N‐[2‐(1H‐azol‐1‐yl)‐1‐arylethylidene]methanamine N‐oxides 9a–q and 10a, b is reported. Directly after the synthesis, ketonitrones 9, 10 were found to exist exclusively in the (E) form, although the C‐methyl analogues 10a and 10b contained a small amount of the corresponding (Z) isomer. The 200‐MHz 1H‐NMR chemical shifts of 9, 10 are also discussed.
Synthese eines mit D‐Glucuronsäure konjugierten Metaboliten von Ciamexon
Authors: Schultz Michael , Zörkler Günter
Published: July 2007

Synthesis of a Metabolite of Ciamexon Conjugated with D‐Glucuronic Acid

Reaction of the alcohol 2 with the glucuronic acid derivative 6 in the presence of Ag triflate yields the protected β‐D‐glucuronide 8 by rearrangement of the orthoester 7. After deacetylation and saponification with pig liver esterase, the deblocked glucuronide 3 can be isolated. Due to the aziridine ring the glucuronic acid derivatives of 2 consist of a mixture of invertomers, as shown by 1H‐NMR spectroscopy.
Die Synthese von Perrottetin F und G, zwei acyclische Bis(bibenzyl)ether aus Radula perrottetii
Authors: Mezey‐Vándor Gabriella , Wiszt A. , Nógrádi M. , Novikov V. P. , Kajtár‐Peredy MÁRia
Published: July 2007

Synthesis of Perrottetin F and G, Two Linear Bis(bibenzyl) Ethers from Radula perrottetii

Perrottetin F and G, two acyclic bis(bibenzyls) with an ether linkage were synthesized using Ullmann and Wittig reactions.
α‐Glucosidasen‐Inhibitoren, 6. Synthese von 1,6‐Anhydro‐D‐glucose‐ und ‐D‐galactose‐Derivaten Herstellung des 1‐Desoxynojirimycins
Authors: Schmidt Richard R. , Michel Josef , Rücker Ernst
Published: July 2007

Methyl‐2,3‐di‐O‐benzyl‐D‐glucopyranosid (2) wird in Anwesenheit von p‐Toluolsulfonsäure und 2,2,2‐Trichlor‐ oder 2,2,2‐Trifluorethanol direkt in die 4‐O‐ungeschützte 1,6‐Anhydropyranose 4 übergeführt. Die als Nebenprodukt gebildete 1,6‐Anhydrofuranose 5 kann durch längere Reaktionszeit angereichert werden. Ebenso werden aus Methyl‐2,3‐di‐O‐benzyl‐D‐galactopyranosid (9) die entsprechenden 1,6‐Anhydro‐Verbindungen 10 und 12 erhalten. Aus der 5‐O‐ungeschützten 1,6‐Anhydroglucofuranose 5 kann in wenigen Stufen 1‐Desoxynojirimycin (31) synthetisiert werden. Dabei erfolgt zur stereoselektiven Einführung von Stickstoff an C‐5 eine Konfigurationsumkehr der 5‐OH‐Gruppe durch Oxidation und Reduktion und Triflat‐Aktivierung für die invertive Azid‐Einführung.
Studies on the Synthesis of Tetrahydrofuran and ‐pyran Derivatives from Terpenes, III. Conversion of cis‐2‐[3‐(2‐Hydroxypropyl)‐2,2‐dimethylcyclopropyl]ethanol to THF and THP Derivatives
Authors: Podlejski Jerzy , Kula JÓSef
Published: July 2007

Sulfuric acid‐catalyzed reaction of cis‐diol 1 leads to a mixture of four heterocyclic alcohols 2–5, which after oxidation yield a mixture of carbonyl compounds 6–9. These compounds were separated and their structures were determined on the basis of spectral data and GC analysis. It was found that THF deriatives (2 and 4) are the main rearrangement products of diol 1, and their high percent ratio in the mixture is discussed as a result of thermodymamic equilibrium between THF (2, 4) and THP (3, 5) derivatives.
Konfigurative Stabilität von S‐Adenosylmethionin – Mutarotation ohne Pseudorotation
Authors: Uzar Horst C.
Published: July 2007

Die Isomerisierung von S‐Adenosylmethionin (1) („SAM”︁) in Anwesenheit verschiedener Anionen und bei verschiedenen Temperaturen wurde durch NMR‐Spektroskopie bestimmt. Die Geschwindigkeit der Epimerisierung am Sulfonium‐Zentrum stimmte dabei gut mit einem von zwei verschiedenen Literatur werten8,9) überein, die auf anderem Weg erhalten worden waren. Die Reaktion erfolgt höchstwahrscheinlich durch pyramidale Inversion und findet sowohl in Lösung als auch im gefriergetrockneten Zustand statt. Konsequenzen für pharmazeutische Anwendungen von 1 und bioorganische Untersuchungen mit 1 werden kurz diskutiert.
Benzenepentamine – Its Easy Accessibility and Use in Syntheses of Pyrazinoquinoxalines
Authors: Praefcke Klaus , Kohne Bernd , Korinth Frank , Psaras Panicos , Nasielski Jaques , Verhoeven Caroline , Nasielski‐Hinkens Raymonde
Published: July 2007

Benzenepentamine (6) has been rediscovered after about 60 years. A simple and very efficient synthetic route is described which yields the very sensitive, colourless 6 in methanolic solution in nearly quantitative yield. Condensations of 6 with two masked forms A and B of glyoxal conveniently lead to two types of amino‐substituted pyrazinoquinoxalines, one with an angular phenanthrene‐type topology (7a), or one with the linear anthracene‐type structure (8a), respectively, with acceptable yields. The α‐diketone benzil also reacts with 6, but less selectively, forming the corresponding tetraphenyl derivatives 7b an 8b of both these heterotricyclic ring systems. The heretofore unknown nitrobenzenepentamine (9), formed in addition to benzenehexamine in reduction reactions of 1,3,5‐trinitrobenzenetriamine, has also been obtained. Based on spectroscopic data, the structures of these two multiamines have been deduced from their condensation products with α‐diketones, in the case of the new pentamine 9 from its first derivatives 7c–e of pyrazino[2,3‐f]quinoxaline.
Bausteine von Oligosacchariden, XCII Synthese von Trisaccharid‐Einheiten der inneren Core‐Region von Lipopolysacchariden
Authors: Paulsen Hans , Heitmann Axel C.
Published: July 2007

Das L‐glycero‐D‐manno‐Heptose‐Derivat 9 läßt sich stereoselektiv mit dem KDO‐Glycosyl‐Akzeptor 6 zu dem α(1→5)‐glycosidisch verknüpften Disaccharid 10 umsetzen. Der hieraus erhältliche Akzeptor 12 wird mit dem KDO‐Glycosyl‐Donator 2 stereoselektiv zu dem verzweigten α(2′→4)‐α(1″→5)‐verknüpften Trisaccharid 21 umgesetzt. Nach der Entblockierung von 10 und 21 ist 3‐Desoxy‐5‐O‐(L‐glycero‐α‐D‐manno‐heptopyransyl)‐D‐manno‐2‐octulopyranosonsäure (18) und 3‐Desoxy‐4‐O‐(3‐desoxy‐α‐D‐manno‐octulopyranosylonsäure)‐5‐O‐(L‐glycero‐α‐D‐manno‐heptopyransyl)‐D‐manno‐2‐octulopyranosonsäure (27) zu erhalten.
Pheromone Synthesis, CXVII Synthesis of Sitophilate, the Aggregation Pheromone of Sitophilus granarius L., and Its Antipode
Authors: Mori Kenji , Ishikura Masaharu
Published: July 2007

The synthesis of sitophilate [(2S,3R‐1] was achieved starting from (S)‐2. Mitsunobu inversion of 7 to give crystalline 3,5‐dinitrobenzoate 8 was the key step to diastereomerically pure 1. The antipode of the pheromone was also synthesized.
Synthese von (+)‐Taxodion
Authors: Haslinger Ernst , Michl Günter
Published: July 2007

Eine stereoselektive Synthese von (+)‐Taxodion (1) aus (‐)‐Abictinsäure (2) über den Eisencarbonyl‐Komplex 4 wird beschrieben. Die Überführung der Carboxyl‐Funktion von 4 in eine Methyl‐Gruppe ist über 5 und 6 in sehr guter Gesamtausbeute möglich. Anschließend werden Sauerstoff‐Substituenten gezielt in die Positionen 12 und 6 eingeführt. Mit BSA wird im letzten Schritt zum Chinonmethid 1 oxidiert. Die 1H‐ und 13C‐NMR‐Resonanzen aller Verbindungen sind eindeutig zugeordnet worden.
Ein Methanoditetrazolo‐[1,3,6,8]tetrazecin aus 5‐(Chlormethyl)tetrazol und Hexamethylentetramin
Authors: Moderhack Dietrich , Goos Karl‐Heinz , Preu Lutz
Published: July 2007

A Methanoditetrazolo‐[1,3,6,8]tetrazecine from 5‐(Chloro‐methyl)tetrazole and Hexamethylenetetramine

In contrast to N‐substituted 5‐(chloromethyl)tetrazoles (1; Ralkyl, aryl), the parent compound 1 (RH) reacts with hexamethylenetetramine to give the methanoditetrazolo‐[1,3,6,8]tetrazecine 4, a rather unusual system. This compound which is also produced on reaction of 7 with formaldehyde occurs in the (6RS,13RS) form.
Eine neue Synthese von (S)‐(+)‐Glycerin‐tosylat
Authors: Pfaendler Hans Rudolf , Maier Franz Karl
Published: July 2007

A Novel Synthesis of (S)‐(+)‐Glycerol Tosylate

Enantiomerically pure (S)‐(+)‐glycerol tosylate (3) was prepared from D‐(+)‐ribono‐γ‐lactone (4) in 43% overall yield.
Synthesis of Mono‐ and Sesquiterpenoids, XV Synthesis of (‐)‐Warburganal, an Insect Antifeedant
Authors: Mori Kenji , Takaishi Hideo
Published: July 2007

The enantioselective total synthesis of (‐)‐warburganal (1) was achieved in 20 steps (8.1% overall yield) starting from (S)‐3‐hydroxy‐2,2‐dimethylcyclohexanone.
Cyclopropandiamine, 3 Diastereomerenreine 1,2‐Cyclopropandicarbonsäuren und Derivate
Authors: Saal Wolfgang Von Der , Reinhardt Robert , Seidenspinner Hubert‐Matthias , Stawitz Josef , Quast Helmut
Published: July 2007

Durch Umsetzung von α,β‐ungesättigten Estern 7 mit α‐Chlorcarbonsäureestern 8 werden die 1,2‐Cyclopropandicarbonsäureester 2a, b, d, e erhalten. Aus den α,β‐ungesättigten Estern 7c, d und dem Schwefelylid 10 entstehen die 1,2‐Cyclopropandicarbon‐säureester 2c, d. Die Ester werden durch fraktionierende Destillation (2a, b, c, e) oder Kristallisation (2d) in 100‐g‐ bis 1‐kg‐Mengen diastereomerenrein erhalten. Crotonsäure‐methylester (7c) reagiert nur langsam mit 8a zu 2d, vorwiegend aber mit sich selbst zu 12. Aus den Diestern 2 werden einige Disäuren 3, Dichloride 4 und Dihydrazide 5 diasereomerenrein gewonnen. Durch trans→cis‐Isomerisierung von trans‐3f mit Acetanhydrid unter Natriumacetat‐Katalyse wird die 3,3‐Dimethyl‐cis‐1,2‐cyclopropandicarbonsäure (cis‐3f) hergestellt. H‐NMR‐Spektren beweisen die Konfiguration der Verbindungen 2–6 und 12. cis‐1,2‐Dimethyl‐1,2‐cyclopropandicarbonsäure‐Derivate neigen zum Ringschluß. So entsteht aus der Disäure cis‐3e mit Phosphorpentachlorid vorwiegend das cyclische Anhydrid 6e neben wenig Dichlorid cis‐4e. Das Dihydrazid cis‐5e spaltet im festen Zustand langsam, in Lösung rasch Hydrazin ab und cyclisiert zu 13, das durch Erhitzen von cis‐5e auf 60–65°C im Hochvakuum rein erhalten wird.
Octacidomycin, ein neues Oligocarbonsäure‐Antibioticum
Authors: Kerber Karl‐Heinz , Lackner Helmut
Published: July 2007

Die Isolierung und Strukturaufklärung von Octacidomycin (6), einem neuartigen Oligocarbonsäure‐Antibioticum, wird beschrieben. Eingehende NMR‐ und massenspektrometrische Untersuchungen seines Octamethylesters (1) lassen in 6 auf eine Verknüpfung von C7 und C5‐Einheiten zu C47H80O16 schließen. Aus 1 entsteht durch Reduktion das Octaol 2 und daraus dessen Octaacetat 3. Die Umsetzung von 2 mit Iodwasserstoffsäure/Phosphor und Lithiumaluminiumhydrid führt über das Octaiodid 4 zum bislang unbekannten 4,10,16,22,28,34‐Hexamethylhentetracontan (5).
Glycosylimidate, 41 6‐O‐Benzylierte Muraminsäure als Glycosylakzeptor – Synthese des GlcNAc‐β(1→4)‐MurNAc‐Disaccharids
Authors: Termin Andreas , Schmidt Richard R.
Published: July 2007

Die α‐Trichloracetimidate 1 und 2 als Glucosamin‐Donoren liefern mit dem 6‐O‐Benzyl‐geschützten Muraminsäure‐Akzeptor 6a die β‐verknüpften Disaccharide 14 bzw. 15 in sehr guten Ausbeuten. Verbindung 14 ergibt durch Abspalten der TBDMS‐Gruppe, Überführung der Azidgruppen in Acetamidogruppen, O‐Debenzylierung und O‐Acetylierung das GlcNAc‐β(1→4)‐MurNAc‐Disaccharid 18‐β und 18‐α. Aus Verbindung 14 wird außerdem der Disaccharid‐Donor 20‐α und aus Verbindung 15 der 4′‐O‐ungeschützte Muraminsäure‐Akzeptor 21 erhalten.
Addition of the Lithium Derivatives of 4‐Alkyl‐3‐morpholinones to Carbonyl Compounds
Authors: Dobrev Alexander , Nechev Ljubomir , Ivanov Christo
Published: July 2007

By addition of the lithium derivatives of some substituted 4‐alkyl‐3‐morpholinones to carbonyl compounds, a series of racemic 2‐(1‐hydroxyalkyl)‐4‐alkyl‐3‐morpholinones 2 and 3 was obtained. The stereochemical course of the reaction is discussed on the basis of the isomer ratio of 2b (determined by 1H‐NMR spectroscopy).
Glycosylations of Ambident Anions of 2(1H)‐ and 4(1 H)‐Pyridone and Stereoselective Synthesis of 2(1 H)‐Pyrimidinone N‐(2′‐Deoxy‐α‐D‐ribofuranoside)
Authors: Seela Frank , Bindig Uwe
Published: July 2007

Glycosylation of the ambident anions of 2(1H)‐pyridone (6) and 4(1H)‐pyridone (11) in the presence of KOH with 2‐deoxy‐3,5‐di‐O‐(p‐toluoyl)‐α‐D‐erythro ‐pentofuranosyl chloride (7) stereoselectively yielded the β‐D‐O‐glycosides 8 and 12, together with anomeric mixtures of the N‐glycosides (9, 10, 13, 14). Under the same conditions, but replacing KOH by LiOH, 2(1 H)‐pyrimidinone (15) exclusively gave the anomerically pure α‐D‐N‐glycoside 17. Proton‐catalyzed O/N‐transformation was stereoselective in the case of 2(1H)‐pyrimidinone O‐β‐D‐ribofuranoside (16) but not in case of 8 or 12. The anomerically pure N‐(2‐deoxy‐α‐D‐ribofuranoside) 17 was prepared in a stereos elective synthesis.
Attempted Synthesis of 3‐Carboxy‐4‐hydroxy‐4‐(trifluoromethyl)tetralone
Authors: Ukerun Sylvester Ohwevwo
Published: July 2007

The reaction of 3‐carboxy‐5,5,5‐trifluoro‐4‐hydroxy‐4‐phenylpentanoic acid (1) with NaH/Me2SO4 gave 3‐carboxy‐5,5,5‐trifluoro‐4‐methoxy‐4‐phenylpentanoic acid (4) and a defluorinated compound 5. 3‐Chlorocarbonyl‐4‐phenyl‐4‐(trifluoromethyl)butanolide (9) was obtained from the reaction of the corresponding 3‐carboxybutanolide 3 with PCl5 at low temperature; heating yielded the 2,5‐furandione 10. Attempted hydrogenation of 10, followed by hydrolysis gave the defluorinated compound 5.
(S)‐5‐Nitro‐2‐pentanol durch Reduktion mit Bäckerhefe
Authors: Hafner Thomas , Reißig Hans‐Ulrich
Published: July 2007

(S)‐5‐Nitro‐2‐pentanol by Reduction with Baker′s Yeast

The title compound 2 is prepared with 96% enantiomeric excess in reasonable yield employing baker′s yeast under aerobic conditions. The absolute configuration has been established by conversion of 2 into (S)‐4,5‐dihydro‐5‐inethyl‐2(3/)‐furanone (4).
Darstellung neuer säureempfindlicher Harze vom sek.‐Alkohol‐Typ und ihre Anwendung zur Synthese von Peptiden
Authors: Barlos Kleomenis , Gatos Dimitrios , Hondrelis John , Matsoukas John , Sotiriou Petros , Moore Graham J. , Schäfer Wolfram
Published: July 2007

Die substituierten Diphenylmethyl‐Harze 5b–e und das α‐Methylbenzyl‐Harz 6 wurden hergestellt und nach der Methode von Mitsunobu mit Trt‐ und Fmoc‐Aminosäuren verestert. Nach wachsender Stabilität ihrer Esterverknüpfung mit Aminosäuren gegenüber Trifluoressigsäure kann man die untersuchten Harze wie folgt einordnen: 6 ≤ 5b<5a ≤ 5c<5d ≤ 5e<4.
Pheromone Synthesis, CXV Synthesis of (Z)‐2‐Ochtoden‐1‐ol, (E)‐2‐Ochtoden‐1‐al, and (Z)‐2‐Ochtoden‐1‐al, the Pheromone Components of the Boll Weevil (Anthonomus grandis)
Authors: Mori Kenji , Itou Masamichi
Published: July 2007

The synthesis of geometrically pure (Z)‐2‐ochtoden‐1‐ol (1), (E)‐2‐ochtoden‐1‐al (2), and (Z)‐2‐ochtoden‐1‐al (3) was achieved starting from myrcene.
Steroide mit einer 17‐Spiro‐dithiolanon‐Struktur
Authors: Annen Klaus , Hofmeister Helmut , Laurent Henry , Hoyer Georg‐Alexander
Published: July 2007

Mit Hilfe einer neuen Abwandlung in der Pregnan‐Seitenkette von 3 wird die Synthese der Dithiolanone 6 und 7 als potentiell wirksame Diuretica beschrieben. Die corticoidnahen Strukturen 13a – 13c mit einer Dithiolanon‐Seitenkette lassen sich aus den entsprechenden 17‐(Acyloxy)‐21‐(mesyloxy)‐Derivaten 12a – 12c durch Behandlung mit einem 10fachen molaren Überschuß an Kaliumthioacetat darstellen.
Synthese der 6‐Methylencarbonsäure‐Derivate von Testosteron und Progesteron
Authors: Handschuh Dieter , Voelter Wolfgang
Published: July 2007

Die 6β‐(Phenylsulfonyl)essigsäure‐methylester‐Derivate 8 bzw. 9 von Testosteron and Progesteron und die analogen 6β‐(Methylsulfonyl)essigsäure‐methylester‐Derivate 10 bzw. 11 werden durch allylische Alkylierung der entsprechenden π‐Allylpalladiumchloridkomplexe 3 bzw. 4 synthetisiert. Die Reaktionsansätze zur Synthese von 8 und 9 liefern nach chromatographischer Trennung die Hauptprodukte 8a bzw. 9a mit S‐Konfiguration und die Nebenprodukte 8b bzw. 9b mit R‐Konfiguration am neu eingeführten Asymmetrie‐Zentrum. Diese Nebenprodukte können in den Ansätzen zur Synthese von 10 und 11 nicht nachgewiesen werden. Dagegen können aus den entsprechenden Ansätzen die Nebenprodukte 9c und 11c mit α‐Konfiguration an C‐17 (Isoprogesteron‐Derivate) isoliert werden. Alkali‐Behandlung der Hauptprodukte führt über Eliminierung und Verseifung zu den entsprechenden 6‐Methylencarbonsäure‐Derivaten: aus 8a und 11a entstehen 16 bzw. 17. Basenkatalysierte Eliminierung von 9a liefert den α,β‐ungesättigten Methylester 19. NMR‐spektroskopische Untersuchungen (NOE, NOESY) von 19g geben Hinweise auf die erwartete E‐Konfiguration.
Curare‐ähnliche „Dimere”︁ der Indolo[2,3‐a]chinolizin‐Reihe mit Bicyclo[3.3.1]nonadien‐Struktur
Authors: Teuber Hans‐Joachim , Quintanilla‐Licea Ramiro , Bats Jan Willem
Published: July 2007

3‐Acetyl‐7,12‐dihydro‐2‐methyl‐6H‐indolo[2,3‐a]chinoliziniumchlorid (1) reagiert mit Benzaldehyd oder Furfural im Mol‐Verhältnis 2:1 unter Piperidin‐Katalyse zu den „Dimeren”︁ 2a, b bzw. 3 mit Bicyclo[3.3.1]nonan‐Gerüst. Natriumtetrahydroborat reduziert 2a zum Bicyclo[3.3.1]nonadien 7, Chlorwasserstoff in Essigsäure dehydratisiert 2a zum Mono‐ und Diolefin 8 bzw. 9. Der am Brücken‐Kohlenstoff‐Atom befindliche Benzol‐(Furan‐)Ring mit eingeschränkter Drehbarkeit beeinflußt insbesondere C‐9 und bewirkt eine Hochfeldverschiebung der NMR‐Signale der dortigen Substituenten. Die Hydroxy‐Gruppen von 2a und 3 sind endo‐ständig und durch Wasserstoff‐Brücken fixiert. Die Stereochemie der Bildungsreaktion von 2a, b wird auf Grund der Röntgenstrukturanalyse von 7 diskutiert.
Allylation‐Assisted Addition of Nitromethane to 2H‐1‐Benzopyran‐2‐ones Substituted in Position 3
Authors: Bojilova Anka , Kostadinova Todorka , Ivanov Christo
Published: July 2007

The addition of nitromethane to 3‐substituted 2H‐1‐benzopyran‐2‐ones 3 and 5 by the action of 1,8‐diazabicyclo[5.4.0]‐undec‐7‐en was investigated. It was found that the reaction proceeds only in the presence of allyl bromide.
Synthesis of Malonaldehyde Monoacetals
Authors: Shi‐Qi Peng , Winterfeldt Ekkehard
Published: July 2007

The synthesis of a series of malonaldehyde monoacetals is described. Selective hydrolysis or transacetalisation of 1,1,3,3‐tetramethoxypropane and its analogues was proved to be a very general technique.
Convenient Preparation of Dimethyl [(3S)‐3‐Methyl‐2‐oxo‐5‐octynyl]‐phosphonate
Authors: Harre Michael , Trabandt Jörg , Westermann Jürgen
Published: July 2007

The diastereoselective alkylation of the chiral Evans intermediate2with 1‐iodo‐2‐pentyne (3) gives the oxazolidinone4. Titanium alkoxide‐catalysed cleavage yields the ethyl ester5, which is used to acylate dimethyl methanephosphonate to the chiral phosphonate6. The optical purity of phosphonate6is checked by separation on a chiral HPLC column and by conversion into the bromo ketone8, an intermediate for the prostacyclin analogue ZK 96480.
Synthesis of a Renin Inhibitor of the Azapeptide Type
Authors: Gante Joachim , Kahlenberg Harald
Published: July 2007

The azapeptide derivative 12 is obtained in a 7‐step synthesis by coupling the components 5 and 11 in the last step. Whereas the azaamino acid residue in 5 is generated by a hydrazine/isocyanate addition, the other coupling steps are done using the carbodiimide/HOBt method. Compound 12 could be shown to inhibit the enzyme renin.
Über die Inhaltsstoffe der Propolis, I
Authors: Seifert Michael , Haslinger Ernst
Published: July 2007

Aus der Propolis (Bienenwaben‐Kittharz) wurden Alkane, Alkene und Alkadiene isoliert. Die Charakterisierung der Verbindungen erfolgte durch GC/MS‐Analyse. Die Positionen der Doppelbindungen wurden nach Methoxymercurierung und Deuterierung durch Analyse des Massen‐Fragmentierungsmusters und deren Z‐Konfiguration durch NMR‐Analyse bestimmt.
Reactivity of Cyanogen towards N‐Substituted Sulfamides: Synthesis of 1,2,5‐Thiadiazole 1,1‐Dioxide Derivatives
Authors: Alkorta Ibon , Arán Vicente J. , Dávila Elena , Ruiz José R. , Stud Manfred
Published: July 2007

The acid‐catalyzed cycloaddition of N‐substituted sulfamides 1a–f with cyanogen affords 2‐substituted 4‐amino‐2,3‐dihydro‐3‐imino‐1,2,5‐thiadiazole 1,1‐dioxides 5a–f which, in turn, could be easily hydrolyzed to give the corresponding 3‐oxo derivatives 2a–f by acid treatment. Direct spectral evidence of amino – imino tautomerism in aminothiadiazole 1,1‐dioxide derivatives has been observed for the first time in compounds 5.
On the Chemistry of Latrunculins A and B
Authors: Blasberger Dina , Carmely Shmuel , Kashman Yoel , Cojocaru Miriam , Spector Ilan , Shochet Nava R.
Published: July 2007

The chemical behavior of latrunculins A (1) and B (2) (Lat A and B) under a variety of reaction conditions is described. The combination of the macrolide, the THP‐lactol, and the 2‐thiazolidinone rings was found to result in interesting unpredicted chemical transformations. The structures of two new Lats, 6,7‐epoxy‐Lat A (3) and Lat M (4) isolated from Latrunculia magnifica are discussed.
N‐Acylcatecholamine und 3,4‐Dihydro‐6,7‐isochinolindiole aus N‐Acyl‐3,4‐dimethoxyphenethylaminen
Authors: Niederstein Yvonne , Peter Martin G.
Published: July 2007

Die N‐[2‐(3,4‐Dimethoxyphenyl)ethyl]acetamide 2a und 2e liefern mit Bortribromid erwartungsgemäß die Catechole 3a bzw. 3e, während aus den halogenierten Acetamiden 2b, 2c, 2f und 2g Mischungen aus den korrespondierenden Catecholen 3b, 3c, 3f bzw. 3g und den 1‐(Halogenalkyl)dihydroisochinolinen 4b, 4c, 4f, bzw. 4g entstehen. Das Trifluoracetamid 2d liefert ausschließlich das Dihydro‐1‐(trifluormethyl)isochinolin 4d. Da höher halogenierte 1‐(Halogenalkyl)‐3,4‐dihydroisochinoline mit der Bischler‐Napieralski‐Reaktion – wenn überhaupt – nur unter drastischen Reaktionsbedingungen zugänglich sind, bietet die Verwendung von BBr3 eine neue Möglichkeit zur Herstellung dieser Verbindungen.
Bausteine von Oligosacchariden, XCIV Synthese von KDO‐haltigen Tri‐ und Tetrasaccharid‐Sequenzen der inneren Core‐ und Lipoid‐A‐Region von Lipopolysacchariden
Authors: Paulsen Hans , Krogmann Christof
Published: July 2007

Der Glycosyl‐Akzeptor 18, mit zwei β‐(1→6)‐glycosidisch verknüpften 2‐Amino‐2‐desoxy‐D‐glucose‐Resten, dessen beide Amino‐Gruppen mit (R)‐3‐Hydroxytetradecansäure acyliert sind, konnte synthetisiert werden. An der 6′‐OH‐Gruppe von 18 lassen sich selektiv Glycosidierugen durchführen. Die Anknüpfung des KDO‐Bromids 21 an 18 ergibt das Trisaccharid 22, aus dem nach Entblockierung α‐KDO‐(2→6)‐β‐D‐GlcNhm‐(1→6)‐D‐GlcNhm (25) erhältlich ist. Die Kupplung des aus 22 erhältlichen 27 mit dem KDO‐Bromid 21 ergibt ein Tetrasaccharid 29, bei dem die Entblockierung zum α‐KDO‐(2→4)‐α‐KDO‐(2→6)‐β‐D‐Glc‐Nhm‐(1→6)‐D‐GlcNhm (33) führt. Sowohl 25 wie 33 können auf Schafs‐Erythrozyten aufgezogen werden und enthalten die KDO‐Reste dann in immunogener Form.
Iridoids, 24 Biomimetic Synthesis of the Monoterpene Alkaloids Xylostosidine and Loxylostosidine A and of Similar Unnatural Compounds by Transformations of the Monoterpene Glycoside Secologanin
Authors: Tietze Lutz F. , Bärtels Christoph , Fennen Jens
Published: July 2007

Condensation of secologanim (1) with cysteamine (5a) affords diastereoselectively 71% of xylostosidine (2), which was transformed into loxylostosidine A (3) by treatment with m‐chloroperbenzoic acid in 70% yield. Similarly, reaction of the functionalized amines 5b, c, 6a–c, and 7 with 1 yields the unnatural monoterpene alkaloids 8–13. The condensation of 1 with 5a was followed by time‐resolved NMR spectroscopy to reveal the stereoselectivity in this transformation.
Synthesis of a protected C‐11/C‐17 segment of mycinolide‐V
Authors: Ditrich Klaus , Hoffmann Reinhard W.
Published: July 2007

Starting from D‐ribonolactone, the cyclopentylidene‐protected dihydroxy ester 12 was prepared in five steps. Reaction of its enolate 13 with benzyloxymethyl iodide gave the esters 15 and 16 with modest selectivity. Each of these was converted into the desired mycinolide building block 32 in seven and six steps, respectively.
Total synthesis of mycinolide‐V
Authors: Hoffmann Reinhard W. , Ditrich Klaus
Published: July 2007

The first synthesis of mycinolide‐V (1) is reported. 1 is the aglycon of mycinamycin‐V, a 16‐membered macrolide antibiotic. The synthesis starts from a C‐3/C‐9 segment, which has been extended to a C‐1/C‐10 building block, and subsequently condensed with a C‐11/C‐17 segment.
Biologically active glycosides from asteroidea, XIX. Glycosphingolipids from the starfish Acanthaster planci 4. Isolation and structure of five new gangliosides
Authors: Kawano Yasuhiro , Higuchi Ryuichi , Komori Tetsuya
Published: July 2007

Five new gangliosides — acanthaganglioside A (1), B (2), C (3), D (4) and E (5) — were purified from the water‐soluble lipid fraction of the chloroform/methanol extract of the starfish Acanthaster planci. Based on chemical and spectroscopic data, the structures of 1–5 were elucidated. The gangliosides consist of one homogeneous long‐chain base, five or six sugars and different fatty acids. Reversed‐phase HPLC using methanol/ammonia/water as solvent was effective in isolating these gangliosides, showing the very close similarity in their structures. Negative FAB mass spectrometry provided important information both on the structure of the sugar moiety and on the molecular mass of the gangliosides. Partial hydrolysis by hot pyridine/water or hot water was useful for structure elucidation of the complex oligosaccharide moieties.
Synthese von (±)‐2‐Oxo‐seychellen und (±)‐2‐Oxo‐4‐epi‐seychellen
Authors: Spitzner Dietrich , Klein Iris
Published: July 2007

Synthesis of (±)‐2‐Oxo‐seychellene and (±)‐2‐Oxo‐4‐epi‐seychellene

Aprotic Michael additions, which generate the functionalized bicyclo[2.2.2]octane 8 from ethyl 2‐methyl‐2,3‐butadienoate (10) and the lithium cyclohexadienolate 9a, are the key steps in the synthesis of 6 (and its 4‐epimer). 6 was made from 8 in 10 steps. The alternative Diels‐Alder reaction of 10 with the trimethylsiloxycyclohexadiene 9b gave exclusively the [2+2] adduct 14 as a 1:1 mixture of diastereomers.
Palladium‐katalysierte Ringschlußreaktionen zu Benzofuranen: ein neuer und effektiver Zugang zu Azacumöstrolderivaten
Authors: Stadlbauer Wolfgang , Laschober Rita , Kappe Thomas
Published: July 2007

Palladium‐Catalyzed Ring Closure Reactions to Benzofuranes: A New and Effective Approach to Azacoumestrols

Azacoumestans (benzofuro[3,2‐c]quinolinones) 4 have been synthesized using the following three methods: ring closure of 3‐aryl‐4‐hydroxy‐2‐quinolones 3a–e by Pd‐catalyzed cyclodehydrogenation, ring closure of 3‐hydroxy‐3‐aryl‐2,4‐quinolinediones 5 by acid‐catalyzed cyclodehydratation, or ring closure of 4‐aryloxy‐3‐iodo‐quinolones 8, which are obtained by rearrangement of iodonium ylides 7, by palladium‐mediated cyclodehydrohalogenation. Only the latter reaction yielded the coumestrol analog dimethoxy derivatives 4c, d, which have been transformed into the hydroxy and acetoxy derivatives 9, 10.
New eudesmane derivatives from Artemisia tournefortiana
Authors: Sanz Juan Francisco , Marco Juan Alberto
Published: July 2007

Extraction of the aerial parts of Artemisia tournefortiana Reichb. yields a new cis‐eudesmanolide 4 and three new eudesmane acids 7, 8, and 10, together with several known compounds. Their structures were deduced by spectroscopic and chemical methods.
Solvolysis of N‐(Chlorosulfinyl)diarylketimines
Authors: Al‐Talib Mahmoud , Tashtoush Hasan
Published: July 2007

N‐(Chlorosulfinyl)diarylketimines 1a–c readily react with alcohols, phenols and thiophenol to give good yields of dialkyl sulfites, diaryl sulfites and dithiosulfites, respectively, besides (diarylmethylene)ammonium chlorides 3a–c. The reactions of 1a with water and carboxylic acids have also been studied.
Transesterification during glycosylation promoted by silver trifluoromethanesulfonate
Authors: Ziegler Thomas , Kováč Pavol , Glaudemans Cornelis P. J.
Published: July 2007

2‐O‐[2,2,2‐D3]Acetyl‐3,4,6‐tri‐O‐acetyl‐α‐D‐galactopyranosyl bromide (3) was prepared and used as the glycosyl donor in studying the silver trifluoromethanesulfonate‐promoted reaction with methyl 2,3,4‐tri‐O‐benzoyl‐β‐D‐galactopyranoside (4) and methyl 2,4,6‐tri‐O‐benzoyl‐β‐D‐galactopyranoside (7). In addition to the expected β‐linked disaccharides, methyl 6‐O‐[2,2,2‐D3]acetyl‐2,3,4‐tri‐O‐benzoyl‐β‐D‐galactopyranoside (6) and methyl 3‐O‐[2,2,2‐D3]acetyl‐2,4,6‐tri‐O‐benzoyl‐β‐D‐galactopyranoside (9), respectively, were formed. The latter compounds were isolated from the reaction mixture and their structures were confirmed based on spectral data. Thus, it has been proven that, with fully acetylated glycosyl halides as glycosyl donors, in silver trifluoromethanesulfonate‐promoted couplings, O‐acetylation of the nucleophile occurs as a side reaction, the acetyl group involved originating from position 2 of the glycosyl halide.
Reactions of organic anions, 173. Oxidative cross‐coupling of enolates with nitronate anions promoted by chloride anions
Authors: Wróbel Zbigniew , Ma̧kosza Mieczysław
Published: July 2007

Nitronate anions derived from primary and secondary nitroal‐kanes undergo cross‐coupling reactions with diethyl alkylmalonate anions in alcohol/DMF solution when treated with silver nitrate. A catalytic amount of chloride ions is necessary to promote selective reaction.
Structural variations of N‐acetylneuraminic acid, 14. Synthesis of the β‐methyl ketosides of 4‐oxo‐, 7‐oxo‐, and 8‐oxo‐N‐acetylneuraminic acid and the corresponding 7,7‐ and 8,8‐dimethoxy derivatives their behaviour towards CMP‐sialate synthase
Authors: Hartmann Michael , Christian Rudolf , Zbiral Erich
Published: July 2007

The 4‐, 7‐, and 8‐oxo‐sialic acid β‐methyl ketosides 7, 10a, and 11a were obtained by transformation of easily available derivatives of N‐acetylneuraminic acid (1a). The carbonyl migration from C‐7 to C‐8 can be carried out under well‐defined conditions with formation of the ketone 11b. Starting from 7‐ and 8‐ketones 17 and 20 the corresponding dimethyl acetals are prepared. The 4‐ketone 7 behaves as a moderate competitive inhibitor of CMP‐sialate synthase [EC 2.7.7.43], whereas the 8‐ketone 11a, the 8,8‐dimethyl acetal 19, and the 7,7‐dimethyl acetal 23 prove not to be inhibitors of this enzyme. The 7‐ketone 10a was not tested because of instability under test conditions at pH 8.5.
Regioselectivity of the amination of some nitroisoquinolines by liquid ammonia/potassium permanganate
Authors: Woźniak Marian , Barański Andrzej , Nowak Krystyna , Poradowska Henryka
Published: July 2007

5‐ and 8‐Nitroisoquinoline and some of their derivatives are aminated in a liquid ammonia solution of potassium permanganate to yield the corresponding 6‐ and 7‐amino compounds. From 5,7‐dinitroisoquinoline the 6,8‐diamino derivative is obtained; 1‐nitroisoquinoline has been found to be unreactive. FMO calculations made for a few nitroisoquinolines confirm the experimentally observed regioselectivity of the amination.
Structural variations of N‐acetylneuraminic acid, 15. Synthesis of 9‐deoxy‐, 7,9‐dideoxy‐, and 4,7,9‐trideoxy‐N‐acetylneuraminic acid and their behaviour towards CMP‐sialate synthase
Authors: Schreiner Erwin , Christian Rudolf , Zbiral Erich
Published: July 2007

The methyl ester of N‐acetylneuraminic acid β‐methyl ketoside (Neu5Ac1Me‐2β‐Me) (1) is used as common starting material for the synthesis of the title compounds. Combined derivatization reactions with reagents thiophosgene, p‐cresol, benzoyl chloride, and acetic anhydride/pyridine lead to the thiocarbonate derivatives 2, 6–8, and 12. Further transformation with iodomethane yields the 9‐iodo compounds 3, 9, and 13, which are reduced by tributyltin hydride to the deoxy derivatives 4, 10, and 14. Hydrolysis of 14, 10, and 4 affords the desired 9‐deoxy, 7,9‐dideoxy‐, and 4,7,9‐trideoxy‐N‐acetylneuraminic acids 15 (9‐d‐Neu5Ac), 11 (7,9‐d2‐Neu5Ac), and 5 (4,7,9‐d3‐Neu5Ac), respectively. — The sialic acid analogues 11 and 5 were activated by CMP‐sialate synthase [E,C.2.7.7.43] to an extent of 30–40 and 50–60%, respectively, relative to N‐acetylneuraminic acid.
Unusual amination by cleavage of an exocyclic C  N linkage with formamide
Authors: Ram Vishnu J. , Kushwaha Dinesh S.
Published: July 2007

Synthesis of various 3‐alkyl‐2‐(1‐pyrazolyl)‐4(3H)‐quinazolinones (1a‐g) and their amination with formamide under different reaction conditions are described.
Synthesis of angular annulated heteroaromatic quinazolino‐[3,2‐a] quinazolines
Authors: Ram Vishnu J. , Kushwaha Dinesh S.
Published: July 2007

A facile synthesis of various 6‐alkyl‐5H‐quinazolino[3,2‐α]‐quinazoline‐5,12(6H)‐diones 7–14 is described, by thermal cyclization of 3‐alkyl‐2‐(methylthio)quinazoline‐4(3H)‐ones 2 with 2‐aminobenzoic acid or 3‐aminonaphthoic acid at 180–190°C.
Reduktive Cyclisierungen mit Ketylen von Bicyclo[2.2.2]octanonen
Authors: Spreitzer Helmut , Kalchhauser Hermann
Published: July 2007

Reductive Cyclizations of Ketyls of Bicyclo[2.2.2]octanones

Depending on the reaction conditions the ketyls 2a/b of bicyclo[2.2.2]octanones 1a/b cyclize to the alcohols 3a/b and 4a/b, respectively.
A simple high‐yielding synthesis of spiro[cyclopropane‐1,2′‐steroids]
Authors: Desai Umesh R. , Trivedi Girish K.
Published: July 2007

A high‐yielding synthesis of biologically active spiro‐[cyclopropane‐1,2′‐steroids] with a Δ4′‐3′‐one moiety by using the Simmons Smith reaction is described. 2‐Methylene‐4‐en‐3‐one steroids are treated with methylene iodide (ratio 1:1).
Sequential analysis of oligosaccharide structures by modern NMR techniques
Authors: Haslinger Ernst , Korhammer Siegfried , Schubert‐Zsilavecz Manfred
Published: July 2007

Sequential analysis of oligosaccharide structures can be achieved by semiselective NMR‐pulse techniques. Gaussianshaped pulses combined with multistep‐relayed coherence transfer and NOE have been used to determine the sequence and assign the carbohydrate resonances of lanatoside C.
Chiral building blocks for the synthesis of nitrogen‐containing natural products, 5. The enantioselective synthesis of optically active, benzene nucleus‐substituted 1‐phenylethylamines from the corresponding acetophenones
Authors: Bringmann Gerhard , Geisler Joerg‐Peter , Geuder Torsten , Künkel Georg , Kinzinger Lioba
Published: July 2007

An efficient two‐step procedure for the synthesis of enantiomerically pure, benzene nucleus‐substituted 1‐phenylethylamines 1 is described, with predictable absolute configuration at the stereogenic center: Imine formation from the substituted acetophenones 6 with (S)‐ or (R)‐1‐phenylethylamine [(S)‐7 or (R)‐7] and subsequent hydrogenation of the resulting Schiff bases 8 over Raney nickel leads to the secondary amines 9 and 10 in high diastereoselectivities. These dibenzylamines are cleaved regioselectively, usually next to the less substituted aromatic ring, giving the desired chiral 1‐phenylethylamines 1 in high yields and enantiomeric purities. Scope and limitations of this new and facile approach to the versatile building blocks 1 are reported.
Organoboron monosaccharides, XVI. Selective syntheses of the methyl α‐D‐furanosides of Lyxose and Mannose using ethyl(dimethoxy)borane
Authors: Dahlhoff Wilhelm V. , Fenzl Wolfgang , Köster Roland
Published: July 2007

Ethyl(dimethoxy)borane is prepared by a two‐step method involving reaction of triethylboroxin with 1,4‐butanediol in a molar ratio of 1:3 to give oligomeric 1,4‐butanediyldioxy‐ethylboranes which are then treated with methanol. D‐Lyxose (1) reacts selectively with ethyl(dimethoxy)borane in the presence of acidic ion exchange resin to form methyl 2,3‐O‐ethylboranediyl‐α‐D‐lyxofuranoside (2) which is deboronated to give methyl α‐D‐lyxofuranoside (4). Similarly, D‐mannose (6) reacts to give methyl 2,3:5,6‐bis‐O‐ethylboranediyl‐α‐D‐mannofuranoside (7), the deprotection of which yields methyl α‐D‐mannofuranoside (8).
On the cyclization to the elusive amino‐4H‐pyran ring some new facts
Authors: Martín‐León Nazario , Quinteiro Margarita , Seoane Carlos , Soto José L.
Published: July 2007

The reaction of 2‐indolinone (1) with arylidenemalononitriles (2) or benzylidenecyanoacetamide (9) yields the Michael adducts 3, 10 and the spiro compound 4a. No cyclization to a 4H‐pyran ring is achieved. Similar results are obtained from the unsaturated lactone 11 and the carbonyl compound 13. In contrast, 1,3‐cyclohexanedione (15) leads to the fused 2‐amino‐4H‐pyran 16 upon reaction with benzylidenemalononitrile (2).
Organic azides in heterocyclic synthesis, 11. Ring closure of 3‐acetyl‐4‐azido‐2‐quinolones to isoxazolo[4,3‐c]quinolones
Authors: Roschger Peter , Stadlbauer Wolfgang
Published: July 2007

Thermolysis of the 3‐acetyl‐4‐azido‐2‐quinolone 6, which was obtained from the corresponding 4‐tosyloxy derivative 5, afforded the ring closed isoxazoloquinolone 7 in good yield.
The complex reaction of acetohydrazides with unsaturated diketones: Alternative cyclizations to 1,2‐diazepin‐3‐ones and pyrazolo[3,4‐b]pyridines
Authors: Alonso Paloma , Martín‐León Nazario , Quinteiro Margarita , Seoane Carlos , Soto José L.
Published: July 2007

The reaction of 2‐cyanoacetohydrazide (1) and 2‐(ethoxycarbonyl)acetohydrazide (26) with unsaturated 1,3‐diketones leading with moderate yields to 1,2‐diazepinones (3, 23, 24) and pyrazolo[3,4‐b]pyridines (5, 15, 20, 25) together with the corresponding acetohydrazones have been studied. The reaction course depends on the temperature and the relative reactivity of the carbonyl groups of the starting materials. When one of these carbonyl groups is less reactive (benzoyl or ethoxycarbonyl groups), the reaction does not yield diazepinones but only pyrazolo[3,4‐b]pyridines and/or acetohydrazones.
Oxime ethers as potential juvenoids: Synthesis of optical isomers
Authors: Wimmer Zdenêk , Vašíčková Soňa , Šaman David , Romaňuk Miroslav
Published: July 2007

Two racemic juvenoids 5 and 6 and their optical isomers 10, 11, 17 and 18 having chiral centres in the aliphatic side chain were synthetized. The second chiral centre in the molecules remained racemic in all derivatives prepared. The absolute configurations of the optically active centres of the enantiomers were determined on the basis of the 1H‐NMR spectral evaluation of the diastereoisomeric MTPA esters 12, 13, 19 and 20 derived from the intermediate alcohols 8 and 15. The optical purity was established by an HPLC analysis of the corresponding MTPA esters. The 1H‐NMR spectra of all compounds as well as the CD spectra of all chiral isomers were measured and discussed.
Glycosylation of 2,3‐diphenylindole and derivatives — Synthesis of O‐, N‐, and C‐glycopyranosides
Authors: El‐Desoky El‐Sayed I. , Abdel‐Rahman Hassan A. R. , Schmidt Richard R.
Published: July 2007

Reaction of different glycosyl donors with 5‐hydroxy‐N‐methyl‐2,3‐diphenylindole (1C) led only to O‐glycosylation (compounds 6a–c and 8c‐α,β). Depending on the O‐protection of the glycosyl donors (2a–c, 3b, 4c), the β‐products were obtained mainly or exclusively. The corresponding N‐unsubstituted indole 1B and donors 2b and 5a, respectively, also yielded only O‐glycosylated products (compounds 11b and 13a). Depending on the glycosyl donor (2a or 2c), the N‐unsubstituted 5‐methoxy‐2,3‐diphenylindole (1A) led to N‐ and/or C‐glycosides (compounds 16a, 14a‐α,β, and 14c‐α,β). The structures were assigned with the help of 1H‐NMR data of these products or their derivatives.
Verbesserte Synthese von N1‐Pyridylthiaminpyrophosphat, einem coenzymatisch aktiven Analogon des Thiaminpyrophosphates
Authors: Neef Holger , Golbik Ralph , Fahlbusch Barbel , Schellenberger Alfred
Published: July 2007

Improved Synthesis of N1‐Pyridylthiamine Pyrophosphate, a Coenzymatically Active Analog of Thiamine Pyrophosphate

Our previously published synthesis of the N1‐pyridyl analog 1b of thiamine pyrophosphate6) is improved resulting in a remarkably higher yield. Key reaction of this new synthetic pathway is the oxidative degradation of 5‐acetylpyridine 8 to the 5‐carboxylic acid 11 via the pyridinium compound 10. Improved preparations of other intermediates are also described. The N1‐pyridylthiamine pyrophosphate analog 1b has been separated and purified by ion exchange chromatography on Sephadex A‐25.
Neue Synthesewege zu Thiophosphatidylcholin mit CSP‐Bindung
Authors: Mlotkowska Barbara , Markowska Anna
Published: July 2007

New Synthetic Routes to Thiophosphatidylcholine with C  S  P Bond

A simple and effective synthesis of thiophosphatidylcholine (4) based on phosphorylation of 2,3‐di(stearoyloxy)‐1‐propa‐nethiol (1a) or 2,3‐di(stearoyloxy)‐1‐(trimethylsilyl)‐1‐propane‐thiol (1b) with 2‐chloro‐2‐oxo‐1,3,2‐dioxaphospholane (2) followed by ring opening of the resultant product 3 is described.
Natural product chemistry, 139. Synthesis of the natural coumarins (E)‐suberenol, cyclobisuberodiene and two other related new coumarins
Authors: Reisch Johannes , Herath H. M. T. Bandara , Kumar N. Savitri
Published: July 2007

The total synthesis of (E)‐Suberenol (1) was carried out under the conditions of palladium‐catalysed Heck condensation. Two other new coumarins, (E)‐7‐methoxy‐6‐(3‐methyl‐1,3‐butadienyl)coumarin [(E)‐suberodiene] (3) and (E)‐7‐methoxy‐6‐(3‐methyl‐1‐butenyl)coumarin [(E)‐suberenene] (4) and cyclobisuberodiene (2) were synthesised from (E)‐suberenol.
Vergleichende Untersuchung zur Diastereoselektivität der O‐Methylierung von sterisch behinderten β‐Ketocarbonsäureestern und ihren Enolen
Authors: Buß Monika , Meier Herbert
Published: July 2007

Diastereoselectivity of the O‐Methylation of Sterically Hindered β‐Ketocarboxylates and Their Enols

The enols 1a, b, and 1c, which exists almost completely in the keto form, have been methylated at the oxygen atom with diazomethane. The regioselective reaction can be catalyzed by methanol, but may loose in that case the diastereoselectivity. A comparison with the methylation of the enolates by iodomethane is discussed.
Thermal degradation of glycosides, III. Degradation of cardenolide glycosides
Authors: Kim Youn Chul , Higuchi Ryuichi , Komori Tetsuya , Abe Fumiko , Yamauchi Tatsuo
Published: July 2007

The thermal degradation of cardenolide glycosides consisting of different sugar moieties and aglycones was examined. On simple heating, the sugar—aglycone linkage of cardenolide glycosides having 2,6‐dideoxy sugar moieties in readily cleaved, to afford their genuine aglycones. On the contrary, cardenolide glycosides possessing 6‐deoxy sugar moieties are resistant to the degradative reaction. Besides the fission of the glycosidic linkages, some interesting reactions also took place. The pyrolyzed products were isolated by chromatography, and the structures were elucidated by spectroscopic evidence.
Transformations starting from biotechnologically available materials, I. A convenient preparative route to 1‐oxa‐5‐azaspiro[2.4]heptane Systems
Authors: Svêtlík Jan , Veverka Miroslav
Published: July 2007

A simple, efficient procedure for the conversion of N‐arylitaconimides 3a—f into novel 5‐aryl‐1‐oxa‐5‐azaspiro[2.4]‐heptane‐4,6‐diones 4a–f using peroxytrifluoroacetic acid is described.
Prolin‐benzylester als chirale Hilfsgruppen in asymmetrischen 1,3‐dipolaren Cycloadditionen mit Nitriloxiden
Authors: Waldmann Herbert
Published: July 2007

Proline Benzyl Esters as Chiral Auxiliaries in Asymmetric 1,3‐Dipolar Cycloadditions

N‐Acryloylproline benzyl ester (1b) reacts with nitrile oxides at temperatures from −78 to 0°C to give isoxazolines 4/5 with diastereomeric ratios of ca. 3:1 and with the (5S) isomer as the predominating. The corresponding N‐methacryloylproline benzyl ester (1c) gives inferior results. The diastereoselectivity is not influenced by the temperature and the substituents of the nitrile oxides. To prove the absolute configuration of the predominating stereoisomer, a reaction sequence is developed which makes use of an enantioselective hydrolysis with pig liver esterase as the key step to generate an optically active isoxazoline with known stereochemistry. In the reactions of the N,N′‐fumaroylbis(proline benzyl ester) (11) with the nitrile oxides the chiral auxiliaries display synergistic stereodirecting influences and, as a consequence, the cycloadducts 12/13 are formed at −78°C with ratios of ca. 9:1.
Biosynthese von Naturstoffen mit einer P  C‐Bindung, V. Das Oxiran‐Sauerstoff‐Atom des Fosfomycins entstammt nicht dem Luft‐Sauerstoff
Authors: Hammerschmidt Friedrich , Bovermann Günter , Bayer Karl
Published: July 2007

Biosynthesis of Natural Products with a P  C Bond, V. — The Oxirane Oxygen Atom of Fosfomycin Is not Derived from Atmospheric Oxygen

Fosfomycin (1) in the culture broth of Streptomyces fradiae was transformed into (amino hydroxypropyl)phosphonic acids 12 and 13. The main product 12 was isolated by ion‐exchange chromatography. Streptomyces fradiae grown in an 18O2‐enriched atmosphere produced unlabelled fosfomycin. For comparison 18O‐labelled diastereomeric (2‐amino‐1‐hydroxypropyl)phosphonic acids 16 and 17 showing an α shift of 0.025 ppm in the 13CC‐NMR spectrum were prepared starting from Boc‐L‐alaninal. (Z)‐1‐[2,3‐2H2]Propenylphosphonic acid was not incorporated into 1. D‐[6,6‐2H2]Glucose afforded 12 with 16% deuterium at C‐1.
Reactions of nitrile oxides and nitrile imines with 4‐arylidene‐2‐phenyl‐5(4H)‐thiazolones
Authors: Coutouli‐Argyropoulou Evdoxia , Thessalonikeos Elisavet
Published: July 2007

Nitrile oxides 2a, b and nitrile imines 2c–e are added to the C  C bond of 4‐arylidene‐2‐phenyl‐5(4H)‐thiazolones 1 to afford spiro‐isoxazolines 3a–d and spiro‐pyrazolines 3e–j, respectively. The cycloaddition reactions are regioselective and only one of the two possible regioisomers is isolated. Reactions of the cycloadducts with nucleophiles lead to isoxazole and pyrazole derivatives 8 and 10 by opening of the thiazolone ring.
Preparative‐enzymatic formation of cytidine 5′‐monophosphosialate by integrated cytidine 5′‐triphosphate regeneration
Authors: Thiem Joachim , Stangier Peter
Published: July 2007

The preparative formation of cytidine 5′‐triphosphate by an enzymatic process with adenylate kinase and pyruvate kinase is described. The enzymes may either be used free, in the “MEEC” technique, or immobilized on a synthetic copolymer of vinyl acetate and N,N′‐divinylethyleneurea (“VA‐Epoxy”). Cytidine 5′‐monophosphosialate synthase (preferably isolated from calf brain) and inorganic pyrophosphatase were used to prepare the activated neuraminic acid cytidine 5′‐monophosphosialate (CMP‐Neu5Ac) from CTP and neuraminic acid in good yield. Finally, both processes could be integrated and led to an in situ approach which, owing to moderate yields, requires further development.
Synthesis and properties of the enantiomers of the two artificial fragrances lilial and methylundecanal
Authors: Enders Dieter , Dyker Hubert
Published: July 2007

The enantiomers of the two artificial fragrances 3‐(4‐tert‐butylphenyl)‐2‐methylpropanal (lilial) and 2‐methylundecanal are synthesized with high enantiomeric purity using the SAMP/RAMP hydrazone method. The enantiomeric excesses are determined by HPLC via the corresponding SASP hydrazones. The olfactorial qualities of the enantiomers are described.
Synthesis of functionalized pyridines by michael addition of benzoyl(thioacetanilides) to arylmethylenemalononitriles and ethyl α‐cyanocinnamates
Authors: Bogdanowicz‐Szwed Krystyna , Lipowska Malgorzata , Rys Barbara
Published: July 2007

The synthesis of substituted 2‐thioxopyridines from benzoyl(thioacetanilides) 1 and arylmethylenemalononitriles or ethyl α‐cyanocinnamates 2 is described. The reaction of 1 with 2b, c gives rise to derivatives of tetrahydro‐ 5 and dihydro‐6‐thioxopyridines 6. A 4,5‐cis configuration of 5 is proposed on the basis of the analysis of the vicinal coupling constants.
A novel diaza‐crown ether and cryptands from glucopyranose and their complex‐forming properties
Authors: Bakó Péter , Fenichel László , Tőke László
Published: July 2007

Chiral diaza‐crown ether 6 and cryptands of type [2.2.2] (9), containing one glucopyranoside unit, have been prepared. Two methods are described for the synthesis of 9. The new cryptand 12 containing two glucopyranoside units has also been prepared. The association constants (Ka) of these compounds with Li, Na, K and NH4 cations have been measured.