bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of Phosphites with 1,4‐Benzoquinone Monoimines
Authors: Boulos Leila Sadek , Hennawy Ibtisam Tadros , Arsanious Mona Hazkial Nasr 
Published: July 2007

AbstractTrimethyl phosphite (2a) reacts with N‐(phenylsulfonyl)‐1,4‐benzoquinone monoimine (1a) to give the respective phosphonate 3c, phosphates 3d, 3e and the alkylated products 3a and 3b. The reaction of triethyl phosphite (2b) with the same quinone imine 1a yields only the phosphate adduct 3f and the amide 3g. Triisopropyl phosphite (2c) reacts with 1a to form the alkylated product 3h. Trimethyl phosphite (2a) gives the phosphate 4a on reaction with N‐(methylsulfonyl)‐ 1,4‐benzoquinone monoimine (1b). In case of the reaction of triethyl and triisopropyl phosphites (2b, c) with 1b only the respective alkylated products 4b–d are obtained. A mechanism is proposed to explain the formation of the new adducts.
Reactions of Organic Anions, 194. Reactions of Carbanions Generated from 2‐(Dialkylamino)‐2‐phenylacetonitriles with Disubstituted Acetylenes
Authors: Zdrojewski Tadeusz , Jończyk Andrzej 
Published: July 2007

AbstractReactions of aminonitriles 1a–e with disubstituted acetylenes 2, 3, carried out in DMSO in the presence of powdered sodium hydroxide and benzyltriethylammonium chloride (TEBAC) as a catalyst, afford either 4 and 5 or a mixture of 4 and 6; unmasking of the carbonyl group in 5a and 6a gives ketones 7 and 8, respectively.
Unsymmetrically Substituted Furoxans, XIV. Synthesis and Structure of a Trimer of the Furoxan System with High Vasodilator and Platelet Antiaggregatory Activity
Authors: Gasco Andrea Marcello , Di Stilo Antonella , Fruttero Roberta , Sorba Giovanni , Gasco Alberto , Sabatino Piera 
Published: July 2007

AbstractThe synthesis and structure of a trimer 5 of the furoxan system are reported. The probable origin of this derivative is the dimerization of the intermediate 4‐phenyl‐3‐furoxancarbonitrile oxide (4) obtained by decomposition of the corresponding nitrolic acid 3. The title compound shows a high level of activity as vasodilator and inhibitor of platelet aggregation.
Diastereoselektive Synthese von Anthracyclinon‐Vorläufern
Authors: Flock Markus , Nieger Martin , Breitmaier Eberhard 
Published: July 2007

Diastereoselective Synthesis of Anthracyclinone Precursors[4 + 2] Cycloaddition of various dienes such as 1‐acetoxy‐1,3‐butadienes 4a, b or 1‐phenylethyloxy‐1,3‐butadienes 4c–g with 1,4‐anthraquinones 3 affords tetracyclic precursors of anthracyclinone. Using the chiral substituted 1,3‐butadienes 4 cycloadducts with d.e. > 98% are obtained. The high stereoselectivity is explained by π stacking.
Hetarylsulfoniumsalze durch Cyclisierung
Authors: Gewald Karl , Rehwald Matthias , Gruner Margit 
Published: July 2007

Hetarylsulfonium Salts by CyclizationReaction of tetrahydrothiophene with the N‐(iodoacetyl)anthranilic acid derivatives 1a, b and 2‐(iodoacetylamino)acetophenone (1c) yields the 1‐(2‐oxoquinolin‐3‐yl)tetrahydrothiophenium salts 3a–c in two steps. Analogously the heterocondensed 1‐(2‐oxopyridin‐3‐yl)tetrahydrothiophenium salts 6 and 7 can be prepared. The 1‐(3‐oxopyridazin‐4‐yl)‐ and 1‐(2‐oxopyridin‐3‐yl)tetrahydrothiophenium salts 10, 13, 16, 18 are synthesized on the same way. From the tetrahydrothiophenium salt 3a the 3‐(alkylthio)‐4‐aminoquinolin‐2(1H)‐ ones 19 arise.
Total Synthesis of rac‐Silyhermin and Its 2‐Diastereomers of Potential Antihepatotoxic Activity
Authors: Antus Sándor , Baitz‐Gács Eszter , Gottsegen Ágnes , Seligmann Otto , Wagner Hildebert 
Published: July 2007

AbstractThe first synthesis of racemic silyhermin (rac‐1a) and its 2‐diastereomers 1b (as a ca. 1:1 mixture) was accomplished by starting from caffeic acid ethyl ester and coniferyl alcohol.
Synthesis of 2′‐Azido‐2′,3′‐didehydro‐2′,3′‐dideoxythymidine
Authors: Mikhailopulo Igor A. , Zaitseva Galina V. , Vaaks Elena V. , Balzarini Jan , De Clercq Eric , Rosemeyer Helmut , Seela Frank 
Published: July 2007

AbstractCompound 15 – the 2′‐azido analog of the anti‐HIV compound 2′,3′‐didehydro‐2′,3′‐dideoxythymidine – was synthesized. Treatment of 5′‐O‐trityl‐β‐D‐ribofuranosylthymine (1) with DAST or MSTF gave the 2,2′‐anhydro derivative 2. The latter and its 3′‐O‐benzoate 3 were used for the synthesis of the 2′‐azido‐2′‐deoxy derivatives 4 and 5. Two routes to the synthesis of 15 from 5 were investigated. (i) Treatment of 5 with DAST gave a mixture of the 5′‐O‐trityl derivatives 12 and 13 as well as 1‐(2‐azido‐2,3‐dideoxy‐3‐fluoro‐β‐D‐xylofuranosyl)thymine (16) along with 2,3′‐anhydro derivative 14 (2%). Detritylation of the mixture yielded 15 (39%) and 16 (12%). (ii) Mesylation of 5 gave 17 which yielded 15 upon saponification and detritylation. Compound 15 showed moderate inhibitory activity against HIV‐1 and HIV‐2 in MT‐4 cells.
Bausteine von Oligosacchariden, CVI. Darstellung synthetischer Antigene von LD‐Heptose‐haltigen Trisacchariden der Core‐Region von Lipopolysacchariden durch Copolymerisation mit Acrylamid
Authors: Paulsen Hans , Höffgen Elisabeth C. 
Published: July 2007

Building Units of Oligosaccharides, CVI. – Preparation of Synthetic Antigens Composed of LD‐Heptose‐Containing Trisaccharides of the Core Region of Lipopolysaccharides by Copolymerization with AcrylamideThe allyl glycosides of the trisaccharide L‐α‐D‐Hep‐(1→3)‐α‐D‐Hep‐(1→5)‐Kdo in the α form 3 and β form 6 and furthermore of L‐α‐D‐Hep‐(1→7)‐L‐α‐D‐Hep‐(1→3)‐L‐α‐D‐Hep in the α form 20 were synthesized. The allyl glycosides were coupled with a cysteamin spacer in a radical‐addition reaction followed by an acylation with acryloyl chloride. The products could be copolymerized with acrylamide to afford the polymers 21, 22 and 23 with the trisaccharide structure as an immunological determinant.
Secondary Metabolites by Chemical Screening, 24. Oasomycins, New Macrolactones of the Desertomycin Family
Authors: Grabley Susanne , Kretzschmar Gerhard , Mayer Marion , Philipps Siegrid , Thiericke Ralf , Wink Joachim , Zeeck Axel 
Published: July 2007

AbstractNew macrolactones, named oasomycin A to D (1 to 4), were discovered by a chemical screening in the culture broth of Streptoverticillium baldacii subsp. netropse (strain FH‐S 1625). The structures were established by detailed spectroscopic analysis. The fundamental 42‐membered lactone moiety of oasomycin A and B (1 and 2) is analogous to that of desertomycin A (5), while the oasomycins C and D (3 and 4) are the first representatives of macrolactones bearing a 44‐membered skeleton. These metabolites can be distinguished by side chain modifications at C‐41 or C‐43 as well as the presence of an α‐linked D‐mannose moiety attached to 22‐OH. Due to the structural similarities the oasomycins are integrated into the desertomycin family. In vitro testing by using the HEP‐G2 cell assay showed oasomycin A (1) to be an inhibitor of de novo cholesterol biosynthesis.
Chemistry of 1,2,4‐triazines, XV. First metalation of 1,2,4‐triazine derivatives
Authors: Plé Nelly , Turck Alain , Quéguiner Guy , Glassl Bernd , Neunhoeffer Hans 
Published: July 2007

Abstract5‐Methoxy‐1,2,4‐triazines 2 were lithiated with lithium 2,2,6,6‐tetramethylpiperidide and the formed 6‐lithio‐5‐methoxy‐1,2,4‐triazines 4 trapped with aldehydes or iodine.
Zur Differenzierung der antennenspezifischen enzymatischen Galaktosylierung durch kernmagnetische Resonanzspektroskopie
Authors: Áts Sándor‐Csaba , Hunkler Dieter , Lehmann Jochen 
Published: July 2007

Differentiation of the Branch‐Specific Enzymic Galactosylation by Nuclear‐Magnetic Resonance SpectroscopyA spacer‐modified biantennary trisaccharide glycoside (2) carrying two GlcNAc end groups was galactosylated by UDP‐Gal and β‐(1→4)‐D‐galactosyltransferase to yield compounds 3a, 3b and 4. The non‐separable monogalactosylated compounds 3a and 3b were investigated by NMR spectroscopy (COSY, COLOC, RELAY) to determine a potential branch‐specific transgalactosylation found for native acceptor‐oligosaccharides (1). Since the “3‐branch” is galactosylated at the same rate as the “6‐branch” the presence not only of the center‐mannosyl unit but also of the flanking mannosyl residues replaced by spacers in compound 2 are necessary for site specificity. magnified image
Solvent‐dependent reversible rearrangement of 4‐(hydroxyimino)hexahydro‐pyrimidines to 4‐aminotetrahydropyrimidine 3‐oxides
Authors: Korbonits Dezső , Tóbiás‐Héja Erzsébet , Simon Kálmán , Kolonits Pál 
Published: July 2007

Abstract1,2‐Disubstituted 4‐hydroxyiminohexahydropyrimidines (8) isomerize in alcohols to yield 1,2‐disubstituted 4‐aminotetra‐hydropyrimidine 3‐oxides (9). In aprotic solvents the opposite transformation (9→8) takes place, presumably by a different mechanism. The structure of the N‐oxide 9a was confirmed by an X‐ray crystallographic analysis. magnified image
Beschleunigung von Substitutionsreaktionen eines Phosphorsäurediesters durch Bis(guanidinium)‐Verbindungen
Authors: Gross Ralf , Dürner Gerd , Göbel Michael W. 
Published: July 2007

Acceleration of Substitution Reactions of a Phosphoric Acid Diester by Bis(guanidinium) CompoundsIon‐pair coordination of phosphoric acid diesters with positively charged guanidines may cause large rate accelerations in substitution reactions. Here we present a comparative study on the catalytical influence of several mono‐ bis‐ and tris(guanidines) and of other cationic compounds. Large rate effects occur if 1,3‐bis(aminomethyl)benzene or 1,2‐ethylenediamine are used as spacers. Further acceleration can be achieved by exchanging guanidinium groups by 2‐aminoimidazolines. The 4800‐fold rate enhancement seen in the best case demonstrates the importance of the bis(guanidinium) moiety of staphylococcal nuclease and gives good perspectives towards future uses of guanidinium compounds as RNA cleaving agents. magnified image
Synthese von Retinoiden mit Aryltetrahydroanthracenstruktur
Authors: Hanefeld Wolfgang , Jung Manfred 
Published: July 2007

Synthesis of Retinoids with Aryltetrahydroanthracene StructureWe describe the synthesis of analogues of the retinoid Temarotene (Ro 15‐0778) (1a), which shows due to its lack of a polar end group no signs of hypervitaminosis A. A variety of substituted tetrahydroanthracenes 6, 8, 11, 13 is prepared starting from 2‐methoxynaphthalene (5b) using palladiumcatalyzed coupling techniques. magnified image
Marine Bakterien, VII. Enzymatische Bromierung von Pseudilinen und verwandten Heteroarylphenolen mit der Chlorperoxidase aus Streptomyces aureofacens Tü 24
Authors: Laatsch Hartmut , Pudleiner Heinz , Pelizaeus Birgit , van Pée Karl‐Heinz 
Published: July 2007

Marine Bacteria, VII. – Enzymatic Bromination of Pseudilins and Related Heteroarylphenols with a Chloroperoxidase from Streptomyces aureofaciens Tü 24During the bromination of various substituted synthetic phenyl pyrroles with a chloroperoxidase from Streptomyces aureofaciens Tü 24, mixtures of bromopyrroles are obtained which are not easily accessible by chemical methods. According to the structure of the pyrroles and the kinetics of their transformation, the reaction centre of the enzyme is situated in a slitlike cavity of about 4 × 7 × 8 Ä. magnified image
Constituents of holothuroideae, IV. Isolation and structure of three new cerebrosides, CE‐2b, CE‐2c and CE‐2d, from the sea cucumber Cucumaria echinata
Authors: Higuchi Ryuichi , Inagaki Masanori , Togawa Kenichi , Miyamoto Tomofumi , Komori Tetsuya 
Published: July 2007

AbstractThree new sphingosine‐type glucocerebrosides, CE‐2b (1), CE‐2c (2) and CE‐2d (3), were isolated by means of highperformance liquid chromatography (HPLC) from a cerebroside molecular species (CE‐2) which was obtained from the less polar fraction of the methanol extract of the sea cucumber Cucumaria echinata. The structures of these cerebrosides were determined on the basis of chemical and spectroscopic evidences. magnified image
Novel concepts in directed biaryl synthesis, XXXIV. Synthesis, optical resolution, and helimerization of dinaphtho[2,1‐b:1′,2′‐d]‐pyran‐4‐one
Authors: Bringmann Gerhard , Schöner Bernd , Schupp Olaf , Peters Karl , Peters Eva‐Maria , von Schnering Hans Georg 
Published: July 2007

AbstractA rational synthesis of the biaryl lactone 3 is described. This bridged biaryl, which gradually helimerizes at room temperature, could be synthesized in a non‐racemic form, chemically by atropo‐selective ring opening with a chiral O‐nucleophile and subsequent ring closure, and chromatographically by HPLC on a chiral phase. For the enantiomerization process (M)‐3 ⇄ (P)‐3, the activation parameters were determined. magnified image
Reduktone von Tetron‐, Thiotetron‐ und Tetramsäuren, II. Reduktone durch Rhodium‐katalysierte Zersetzung von Diazoverbindungen
Authors: Stachel Hans‐Dietrich , Poschenrieder Hermann , Redlin Jutta , Schachtner Josef , Zeitler Klaus 
Published: July 2007

Reductones of Tetronic, Thiotetronic and Tetramic Acids, II. – Reductones by Rhodium‐Catalyzed Decomposition of Diazo CompoundsThe diazoketones 2 have been synthesized by diazo transfer reaction with 2‐azido‐3‐ethylbenzthiazolium tetrafluoroborate. The rhodium‐catalyzed decomposition of compounds 2 in tert‐butyl alcohol at 130°C furnishes the reductone monoethers 3 and after deprotection the aci‐reductones 4. Methylation of compounds 4 with diazomethane proceeds stepwise leading first to the monoethers 5 and then to the diethers 6. The thiolactone 4b and even more the lactams 4c and 4d are stronger reducing agents than the lactone 4a. magnified image
Synthesis of doubly labeled enantiomerically pure (R)‐mevalonolactone from lactic and malic acid
Authors: Krohn Karsten , Meyer Annegrete 
Published: July 2007

AbstractEnantiomerically pure 13C‐ and 1H‐labeled (R)‐mevalonolactones are prepared from (S)‐malic and/or (S)‐lactic acid by Seebachs methodology of self‐reproduction of chirality. The two reaction pathways are complementary in the possibilities of multiple isotopic labeling. The labeling potential is exemplified by the synthesis of a doubly 13C, 1H‐labeled, one 13C‐, and one 1H‐labeled mevalonolactone. magnified image
1,3‐Dithiole mit anelliertem Cyclopentadienring
Authors: Hartke Klaus , Timpe Carsten 
Published: July 2007

1,3‐Dithiols with an Annulated Cyclopentadiene Ring5‐Chloro‐2‐cyclopenten‐1‐ones 4 react with sodium N, N‐di‐alkyldithiocarbamates to form the dithiocarbamic esters 5. These are cyclized by strong acids to yield either in a Michael addition the iminium salts 6 or in a condensation reaction the iminium salts 7. Sulfhydrolysis of 7 gives rise to the 4H‐cyclopenta‐1,3‐dithiol‐2‐thione 8. By cleavage of dithiuram disulfides 10 with sodium cyclopentadienide the [(dial‐kylamino)thiocarbonylthio]cyclopentadienes 12 and 13 are formed. They condense with acetone/pyrrolidine to give either the pentafulyenes 16 or the dihydropentalenes 17. magnified image
Eine einfache Synthese der enantiomeren (E)‐9‐Hydroxy‐2‐decensäuren
Authors: Schweitzer Stefan , Voß Gundula , Gerlach Hans 
Published: July 2007

Simple Synthesis of the Enantiomeric (E)‐9‐Hydroxy‐2‐decenoic AcidsThe enantiomeric (E)‐9‐Hydroxy‐2‐decenoic acids (1), components of the swarm settling pheromone in Apis mellifica L. (honey bee) have been synthesized. The lithium derivative of 1‐hexyne was treated with (R)‐(+)‐methyloxirane (2), (S)‐(−)‐2 or (±)‐2 to give the alkynols (R)‐(−)‐3, (S)‐(+)‐3 or (±)‐3, which could be isomerized with the sodium salt of 1,3‐propanediamine to give (R)‐(−)‐8‐nonyn‐2‐ol (4) and (±)‐4. These were methoxycarbonylated to produce the esters (R)‐(−)‐5, (S)‐(+)‐5 or (±)‐5. Selective hydrogenation in pyridine with Pd/BaSO4 as catalyst gave the (Z)‐esters (R)‐(−)‐6, (S)‐(+)‐6 or (±)‐6 which could be isomerized with photochemically generated phenylthio radicals to produce the (E)‐esters (R)‐(–)‐7, (S)‐(+)‐7 or (±)‐7. The acids present in the pheromone (R)‐(−)‐1, (S)‐(+)‐1 and (±)‐1 could be obtained by basic hydrolysis of the esters. The minor but important component 8 of the swarm settling pheromone has been synthesized by treating the Grignard reagent obtained from 5‐bromo‐guaiacol benzyl ether with ethylene oxide to give 9 in high yield. Hydrogenolytic removal of the benzyl group in 9 produced 8 directly. magnified image
Enzymes in organic synthesis, 19. The enzyme‐catalyzed sequential esterification of (±)‐anti‐2,4‐dimethylglutaric anhydride. – An efficient route to enantiomerically enriched mono‐ and diesters of anti‐2,4‐dimethylglutaric acid
Authors: Ozegowski Rüdiger , Kunath Annamarie , Schick Hans 
Published: July 2007

Abstract(±)‐anti‐2,4‐Dimethylpentanedioic anhydride (rac‐1) was converted in good yields and with high enantiomeric excess by an enzyme‐catalyzed sequential esterification into the (2R,4R)‐monoester 2 and the (2S,4S)‐diester ent‐3. Best results were obtained with Novozym 435, a lipase from Candida antarctica. magnified image
Electroorganic synthesis, 56. Synthesis of advanced prostaglandin precursors by Kolbe electrolysis, I. – Preparation of (1′R,4′S,3RS)‐3‐(cis‐4‐acetoxycyclopent‐2‐enyloxy)‐3‐ethoxypropionic acid
Authors: Weiguny Jens , Schäfer Hans J. 
Published: July 2007

AbstractThe key intermediate of a novel synthesis of prostaglandin precursors, (1′R,4′S,3R/S)‐3‐(cis‐4‐acetoxycyclopent‐2‐enyl oxy)‐3‐ethoxypropionic acid (3), is prepared by two different synthetic sequences: In a first strategy transacetalization of ethyl 3,3‐diethoxypropionate (6) with (1R, 4S)‐4‐acetoxy‐1‐hydroxy‐2‐cyclopentene (7) leads to the formation of the mixed acetal 8. By subsequent hydrolysis and acylation 8 could be converted into acid 3 in six steps in 6% overall yield. However, the generation of acid 3 by bromoalkoxidation of 3‐ethoxyacrylates 13d, e and subsequent electrochemical reduction proved to be more efficient. In this reduction it is possible to debrominate the α‐bromo esters 14d, e and to remove the 2‐haloethyl ester group in one step. Using this reaction sequence, we could synthesize acid 3 in five steps in 38% overall yield. magnified image
Synthese isomerer ϵ‐hydroxycarbonsäure‐methylester
Authors: Arth Christoph , Clemens Martina , Meise Werner 
Published: July 2007

Synthesis of Isomeric Methyl ϵ‐HydroxycarboxylatesThe synthesis of the three isomeric methyl ϵ‐hydroxycarboxylates 3, 6 and 10a in good overall yields is described. magnified image
Synthesis of 1‐Azabicyclo[3.3.1]nona‐3,6‐diene Derivatives by a Modified Prins Reaction
Authors: Csuzdi Emese , Ling István , Ábrahám Gizella , Pallagi István , Sólyom Sándor 
Published: July 2007

AbstractIntramolecular electrophilic cyclization reactions were performed with 1‐(3‐oxo‐3‐phenylpropyl)‐1,2,5,6‐tetrahydropyridine derivatives 1a–p in strong acids to give 4,6‐diphenylsubstituted 1‐azabicyclo[3.3.1]nonadienes 2a–p. Some qualitative observations were made on substituents and reaction conditions influencing the ring closure reaction. Naphthylsubstituted starting compounds 3a, b were converted into pentacyclic compounds 4a, b which represent a new ring system, suggesting the occurrence of a carbenium ion intermediate in the ring closure reaction. Some of the compounds 2a–p show remarkable antifungal and antibacterial effects. magnified image
Fluorogenic Substrates Containing 7‐Amino‐4‐methyl‐2‐quinolinone for Aminopeptidase M, Chymotrypsin, Elastase and Trypsin, Determination of Enzyme Activity
Authors: Tzougraki Chryssa , Noula Catherine , Geiger Reinhard , Kokotos George 
Published: July 2007

AbstractSeveral new fluorogenic substrates for four proteases were synthesized by coupling the highly fluorescent 7‐amino‐4‐methyl‐2‐quinolinone (AMeq) with appropriate amino acids and peptides. Compounds HCl · H‐Ala‐NH‐Meq (1) and HCl · H‐Leu‐NH‐Meq (2) are substrates for aminopeptidase M, Glt‐Tyr‐NH‐Meq (3) and Glt‐Leu‐Tyr‐NH‐Meq (4) for chymotrypsin, Boc‐(Ala)4‐NH‐Meq (5) for elastase and Z‐Arg‐NH‐Meq (6) for trypsin. The kinetic parameters for the hydrolysis of the new substrates were determined and showed that each new substrate is suitable for a convenient fluorometric assay of the corresponding enzyme. magnified image
Novel Concepts in Directed Biaryl Synthesis, XXXVIII. Synthesis and Structure of a Protected Lactolate‐Bridged Biaryl with Relevance to the Atropisomer‐Selective Ring Opening of Biaryl Lactones
Authors: Bringmann Gerhard , Schöner Bernd , Peters Karl , Peters Eva‐Maria , von Schnering Hans Georg 
Published: July 2007

AbstractThe preparation and crystal structure of the O‐methyl‐protected analog 5 of a lactolate‐type intermediate 3 in the atropisomer‐selective ring opening of configuratively unstable lactone‐bridged biaryls 1 is described. Thus, 5a could be prepared by oxidation of the cyclic ether 7a to give the substituted pyrylium salt 6a and subsequent reaction with methanolate. Attempts to similarly prepare the more strained higher homologous 5, i.e. with a higher steric hindrance next to the biaryl axis, failed. Structural information on 5a could be obtained through X‐ray crystallography, but no decoalescence was observed in the low‐temperature NMR spectrum. magnified image
Total Syntheses, Optical Rotations and Fragrance Properties of Sandalwood Constituents: (−)‐(Z)‐ and (−)‐(E)‐β‐Santalol and Their Enantiomers, ent‐β‐Santalene
Authors: Krotz Achim , Helmchen Günter 
Published: July 2007

AbstractEnantiomerically pure 5‐norbornene‐2‐carboxylic acids 4, obtained by asymmetric Diels‐Alder additions, were oxidatively degraded to (+)‐ and (−)‐2‐norbornanone [(+)‐, (−)‐21] and (+)‐ and (−)‐3‐methyl‐2‐norbornanone [(+)‐, (‐)‐11] which were converted into the title compounds by stereoselective alkylations, subsequent cis‐ and trans‐selective Wittig reactions and reductions. Precise optical rotations were determined for (Z)‐ and (E)‐β‐santalol (1 and 2) and β‐santalene (3a) which were obtained by total synthesis and, in addition, by isolation from East Indian sandalwood oil. magnified image
Synthesis of Uridine with Methylene‐2‐thiohydantoin as 5‐Substituent
Authors: El‐Barbary Ahmed A. , Khodair Ahmed I. , Pedersen Erik B. , Nielsen Claus 
Published: July 2007

Abstract5‐Formyl‐1‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)uracil (4) was synthesized from 5‐formyluracil (2) and 1,2,3,5‐tetra‐O‐acetyl‐β‐D‐ribofuranose (3) and condensed with 2‐thiohydantoin derivatives 5 by using piperidine as the catalyst to give 5‐(uridin‐5‐ylmethylene)‐2‐thiohydantoin (8a) and 3‐phenyl‐5‐(uridin‐5‐ylmethylene)‐2‐thiohydantoin (8b) after deprotection with sodium methoxide in methanol. Compound 8a was also obtained in an inversed reaction sequence from 5‐formyluracil starting with condensation with 2‐thiohydantoin and then with 3. The compounds 8a and 8b did not show any activity against HSV‐1 or HIV‐1. magnified image
A Stereoselective Synthesis of threo‐3‐Hydroxyglutamic Acid
Authors: Dell'Uomo Natalina , Di Giovanni Maria C. , Misiti Domenico , Zappia Giovanni , Monache Giuliano Delle 
Published: July 2007

AbstractThe highly stereoselective iodocyclocarbamation of the chiral Z olefins 6 and 12, derived from the corresponding α‐amino acid, yields threo‐3‐hydroxy‐D‐ and ‐L‐glutamic acid (1 and 2). magnified image
Glycosyl Imidates, 66. Synthesis of the Tetrasaccharide Moiety of Plant Growth Regulator Calonyctin A
Authors: Jiang Zi‐Hua , Schmidt Richard R. 
Published: July 2007

Abstract3‐O‐Benzyl‐protected quinovose 6 was transformed into 1,2‐O‐unprotected derivative 9 which on treatment with TBS‐Cl in the presence of a base gave selectively 2‐O‐unprotected glycosyl acceptor 10. Similarly, 3‐O‐allyl‐protected quinovose 11 was transformed into 1,2‐O‐unprotected derivative 14. 1,2‐O‐Acetylation of 14, selective removal of the 1‐O‐acetyl group with hydrazinium acetate, and subsequent treatment with trichloroacetonitrile in the presence of DBU furnished the versatile 2‐O‐acetyl‐3‐O‐allyl‐protected quinovosyl donor 17. Reaction of donor 17 with acceptor 10 in the presence of TMSOTf as the catalyst gave disaccharide 19. Treatment of 19 with NaOMe/MeOH provided 2b‐O‐unprotected derivative 20 which gave with rhamnosyl donor 18 in the presence of TMSOTf as the catalyst trisaccharide 21. 3b‐O‐Deallylation of 21 and subsequent reaction with donor 17, again in the presence of TMSOTf as the catalyst, gave target tetrasaccharide 2. Removal of all O‐protective groups furnished D‐Quiß(1→3)[L‐Rhaα(1→2)]D‐Quiß(1→2)D‐Qui (3), the tetrasaccharide moiety of calonyctin A. magnified image