bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselective hydroxyalkylations of (S)‐2‐azetidinecarboxylic acid
Authors: Seebach Dieter , Vettiger Thomas , Müller Hans‐Martin , Plattner Dietmar A. , Petter Walter 
Published: July 2007

AbstractThe enolate generated fromS‐phenyl (S)‐1‐benzyl‐2‐azetidinecarbothioate is converted into racemic products2by treatment with electrophiles. The bicyclic oxazolidinone derivative12has been prepared from trimethylsilyl (S)‐1‐(trimethylsilyl)‐2‐azetidinecarboxylate (11) and pivalaldehyde without racemization. Addition of12to aldehydes and hydrolysis gives the products13 a‐h. The structure of the adduct13 hfrom 4‐pyridinecarbaldehyde was determined by X‐ray crystal structure analysis, proving that the trigonal centers of the bicyclic enolate and of the aldehyde have combined with relative topicityunlike. Thus, the reaction resembles that of the homologous proline derivative described previously, and the novel products are formallyD‐allo‐threonines with an ethylene bridge between the nitrogen and the adjacent carbon atoms (Scheme 4) and with absolute configurationR,R. The mechanism of the C  C bond‐forming reaction is discussed.
Synthesen mit Nitrilen, LXXXVII. Chromoionophore durch Addition von N‐Phenyl(aza‐15‐krone‐5) an reaktive Dicyanmethylenverbindungen
Authors: Junek Hans , Klade Manfred , Biza Peter , Geringer Michael , Sterk Heinz 
Published: July 2007

Syntheses with Nitriles, LXXXVII. — Chromoinophores by Addition of N‐Phenyl(aza‐15‐crown‐5) to Reactive Dicyanomethylene CompoundsAddition of N‐phenyl(aza‐15‐crown‐5) (2) to dicyanomethylene compounds, i.e. the pyrazolylidenemalonitriles 1a–e, leads to the colorless (azacrownphenyl)(pyrazolyl)malonitriles 3a–e. Heating or photolysis of 3 eliminates hydrocyanic acid to give the deeply colored polymethines 4a–e. A corresponding reaction occurs between the indanylidenemalonitrile 5 and the crown ether 2 leading to adduct 6, which can be converted into the polymethine 7 by heating or photolysis. For evaluation of constants of the complex formation with sodium or potassium ions 1H NMR chemical shift measurements have been performed.
Azole, 31. Stellvertretende nucleophile Substitution von Wasserstoff in Nitrobenzotriazol‐Derivaten
Authors: Bernard Marek K. , Szoja Cezary , Wrzeciono Urszula 
Published: July 2007

Azoles, 31. — Vicarious Nucleophilic Substitution of Hydrogen in Nitrobenzotriazole Derivatives4‐, 5‐, 6‐ and 7‐Nitrobenzotriazole derivatives 1a‐1f, 4a and 4b react with carbanions of chloromethyl, bromomethyl, and α‐chloropropyl phenyl sulfones (2a‐2c) to give products of the vicarious nucleophilic substitution of hydrogen in ortho and para or exclusively in ortho position with respect to the nitro group. The structures of the products have been determined by means of 1H‐NMR spectroscopy. On treating with 2c, 1e gives the unexcepted compound 6.
Chemie der Amino‐oxime, XIX. Umsetzung von β‐Benzylamino‐oximen mit Sulfurylchlorid
Authors: Gnichtel Horst , Köhler Christoph 
Published: July 2007

Chemistry of Amino Oximes, XIX. — Reaction of β‐Benzylamino Oximes with Sulfuryl Chloride3,4‐Dihydro‐2H‐1,2,6‐thiadiazine 1,1,6‐trioxides 2 were prepared from anti‐β‐benzylamino oximes 1 and sulfuryl chloride. Tetrahydro‐2H‐1,2,6‐thiadiazin 1,1‐dioxides 3 were formed by reduction with NaBH4 and β‐hydroxylimino sulfamic acid derivatives by hydrolysis, alkoholysis, and aminolysis with secondary amines. With primary amines, 2 afforded pyrazolines 7; syn‐β‐benzylamino oximes 9 and sulfuryl chloride yielded pyrazolines 10.
Total synthesis of methynolide
Authors: Ditrich Klaus 
Published: July 2007

AbstractIn this paper the synthesis of methynolide (1), the aglycone of methymycin, a 12‐membered macrolide antibiotic is described. We have used the chiral C‐1 to C‐8 segment 10 which has been combined with the C‐9 to C‐13 segment 9 to form the carbon skeleton of methynolide. Cyclization of the seco‐acid 14 has been accomplished by intramolecular esterification.
1,3‐dipolar cycloaddition reactions of 1‐aryl‐N‐methyl‐2(1H‐azol‐1‐yl)‐ethanimine N‐oxides to olefins
Authors: Mullen George B. , Bennett Grace A. , Swift Patricia A. , Marinyak David M. , Dormer Peter G. , Georgiev Vassil St. 
Published: July 2007

AbstractThe regio‐ and stereoselectivity of the 1,3‐dipolar cycloaddition reaction of 1‐aryl‐N‐methyl‐2‐(1H‐azol‐1‐yl)ethanimine N‐oxides 6 to monosubstituted olefins 7 were investigated. The reaction is regioselective, leading to the corresponding C‐5 substituted isoxazolidines 8/9 as cis/trans diastereomeric mixtures. The cis isomers, which are the predominant species of the mixtures, are readily separated by flash chromatography on neutral silica gel.
Thermal valence rearrangements of heterocycles, 3. A key aziridine intermediate of the Δ4‐isoxazoline‐pyrrole rearrangement
Authors: Mullen George B. , Bennett Grace A. , Georgiev Vassil St. 
Published: July 2007

AbstractUtilizing the spiro[adamantane‐Δ4‐isoxazoline] precursor 10, a key 2‐acylaziridine intermediate (11) has been isolated, thus providing conclusive evidence that an initial ring contraction may be considered to be the first step of the Δ4‐isoxazoline‐pyrrole rearrangement.
Synthese von [1,1,3‐Trioxo‐1,2‐benzisothiazol‐2(3H)‐yl]keten‐S,S‐acetalen und deren Hydrazinolyse
Authors: Dölling Wolfgang , Herrmann Cornelia , Augustin Manfred 
Published: July 2007

Synthesis of [1,1,3‐Trioxo‐1,2‐benzisothiazol‐2(3H)‐yl]ketene S,S‐Acetals and Their Reaction with Hydrazine HydrateThe previously unknown ketene S,S‐acetals 2, 3, and 4 are prepared by dithiocarboxylation reaction of methylene‐active saccharin derivatives 1 in the presence of sodium hydride/carbon disulfide in dry DMF followed by alkylation. Compounds 2a, 3a, and 4a are treated with hydrazine hydrate (85%) to give 2‐hydrazono‐3,3‐bis(methylthio)propiophenone (6a) and methyl or ethyl pyruvate 6b or 6c, respectively.
Studies on isocyanides. Synthesis of N‐substituted 2‐isocyanocarboxamides
Authors: Bossio Ricardo , Marcaccini Stefano , Pepino Roberto 
Published: July 2007

AbstractThe Ugi four‐component condensation between isocyanides, aldehydes, and ammonium formate affords N‐substituted 2‐formylaminocarboxamides 1 which are dehydrated with POCl3/NEt3 to give the title compounds.
(1S,3S,5S)‐2‐Amino‐3‐methoxymethyl‐2‐azabicyclo [3.3.0]octan: SAMBO — ein neuer chiraler Hilfsstoff
Authors: Martens Jürgen , Lübben Stefan 
Published: July 2007

(1S,3S,5S)‐2‐Amino‐3‐methoxymethyl‐2‐ azabicyclo[3.3.0]octane: SAMBO — a New Chiral Auxiliar(1S,3S,5S)‐2‐Amino‐3‐methoxymethyl‐2‐azabicyclo[3.3.0] octane (SAMBO) (8) was synthesized with an overall yield of 48% starting from the α‐amino acid derivative benzyl (1S,3S,5S)‐2‐azabicyclo[3.3.0]octane‐3‐carboxylate (1) by a six‐step procedure.
Antibiotics from gliding bacteria, XLII. Chemical modification of sorangicin A and structure — Activity relationship I: Carboxyl and hydroxyl group derivatives
Authors: Jansen Rolf , Schummer Dietmar , Irschik Herbert , Höfle Gerhard 
Published: July 2007

AbstractThe synthesis of selectively protected sorangicin A derivatives and their application in the modification of the hydroxyl groups and the carboxyl group in sorangicin A (1) is described. Esters, amides, and sorangicins modified at the hydroxyl groups were prepared and their activities against Staphylococcus aureus, Escherichia coli, and their in vitro inhibition of RNA polymerase were examined. Although no sorangicin A derivatives with superior biological activity were observed, some derivatives completely retained their antibiotic activity or were slightly improved in their activity with certain strains.
Isolierung und Struktur der vier Hauptsaponine aus Solidago gigantea var. serotina
Authors: Reznicek Gottfried , Jurenitsch Johann , Kubelka Wolfgang , Michl Günter , Korhammer Siegfried , Haslinger Ernst 
Published: July 2007

Isolation and Structure of the Four Main Saponins from Solidago gigantea var. serotinaThe four main saponins from Solidago gigantea Ait. var. serotina (O. Kuntze) Cronq. were isolated. The giganteasaponins 1 — 4 are new bis‐desmosidic triterpensaponins containing 9 or 10 sugar units with bayogenin as aglycone. Their structures were determined by modern NMR techniques and GC/MS without extensive degradation studies.
Biologically active glycosides from Asteroidea, XXIII. Synthesis of acanthacerebroside A
Authors: Sugiyama Shigeo , Honda Masanori , Komori Tetsuya 
Published: July 2007

Abstract(R)‐2‐Hydroxytetracosanoic acid (2), prepared by using the chiral building block benzyl (R)‐2,3‐epoxypropyl ether (7), was coupled to (2S,3S,4R)‐2‐amino‐1,3,4‐hexadecanetriol (3) to give the ceramide 4. Glycosidation of 4 with D‐glucopyranose affords acanthacerebroside A, (2S,3S,4R)‐1‐O‐(β‐D‐glucopyranosyl)‐2‐[(R)‐2‐hydroxytetracosanoylamino]‐1,3,4‐hexadecanetriol (1).
Synthesis of 3′‐azido‐2′,3′‐dideoxy‐β‐D‐arabino‐hexopyranosyl nucleosides
Authors: Hansen Poul , Lau Jesper , Pedersen Erik B. , Nielsen Carsten M. 
Published: July 2007

AbstractThe α,β‐unsaturated D‐sugar aldehyde 2, prepared from tri‐O‐acetyl‐D‐glucal, was converted into 1‐O‐acetyl‐3‐azido‐2,3‐dideoxy‐α‐D‐arabino‐pyranose (3) by reaction with sodium azide in a mixture of acetic acid and water followed by acetylation. Reaction of 3 with silylated pyrimidines using TMS triflate as catalyst followed by deprotection with saturated ammonia in methanol afforded 3′‐azido‐2′,3′‐dideoxy‐β‐D‐arabino‐hexopyranosyl nucleosides 4.
Synthesis of 3‐heptyl‐ and 3‐nonyl‐2,4(1H,3H)‐quinolinediones
Authors: Laschober Rita , Stadlbauer Wolfgang 
Published: July 2007

Abstract3‐Alkl‐3‐hydroxy‐2,4‐(1H,3H)‐quinolinediones 4, which are metabolites of some Pseudomonas species, were synthesized by oxidation of the corresponding 4‐hydroxy‐2(1H)‐quinolones 3. By halogenation of 3 the 3‐chloro‐ and 3‐bromo‐2,4‐(1H,3H)‐quinolinediones 5 and 7, respectively, are obtained. Exchange of the chloro substitutent in 5 with sodium azide yields the 3‐azido derivatives 8, while reaction with potassium fluoride affords the 3‐fluoroquinolinediones 6.
Synthesis of Vinca alkaloids and related compounds, LIV. Synthesis of (±)‐16‐deethyl‐vincamines, (Deethyl)‐16‐deethyl‐apovincamines, and their 10‐bromo derivatives
Authors: Sápi János , Szabó Lajos , Thurner Angelika , Baitz‐Gács Eszter , Tamás József , Kalaus György , Szántay Csaba 
Published: July 2007

AbstractA versatile method for introducing a functionalized side chain into enamines 9a and 11a is described. This procedure provides an easy access to 16‐deethyl‐vincamines 16, 17 and 16‐deethyl‐apovincamines 18–21.
A short route to 3′‐deoxy‐3′‐fluorothymidine
Authors: Motawia Mohammed S. , Pedersen Erik B. 
Published: July 2007

AbstractThe 5‐OH‐protected methyl glycosides 2 and 3 were epimerized to give the corresponding epimers 6 and 7 via an oxidation‐reduction procedure. Reaction of 6 with diethylamino‐sulfur trifluoride (DAST) afforded the fluoro sugar 8, which was coupled with thymine to give 3′‐deoxy‐3′‐fluorothymidine (12) after deprotection with saturated ammonia in methanol.
Über neue Säuren im ostindischen Sandelholzöl
Authors: Nikiforov Alexej , Jirovetz Leopold , Machatschek Susanne , Stanek Wolfgang , Buchbauer Gerhard 
Published: July 2007

New Acids in the East Indian Sandalwood OilThree new terpenoic acids, dihydro‐α‐norcurcumenic acid (2), α‐bergamotenic acid (3), and dihydro‐α‐santalic acid (4), could be identified by means of GC‐MS and GC‐FTIR techniques as genuine constituents of the East Indian sandalwood oil. The former postulated γ‐santalic acid (1) could not be detected. Also a series of pyrolytic experiments did not lead to its formation.
Pheromone synthesis, CXXII. (E)‐ and (Z)‐tetradecenyl formate, potent sex pheromone mimics against the yellow peach moth
Authors: Mori Kenji , Watanabe Hidenori , Fujiwhara Mitsuhiko , Kuwahara Shigefumi 
Published: July 2007

AbstractSynthesis and biological evaluation of (E)‐ and (Z)‐8‐tetradecenyl formate (3, 4) as pheromone mimics was executed. A 10:1 mixture of the (E)‐ and (Z)‐formate was shown to be as attractive as a 10: 1 mixture of (E)‐ and (Z)‐10‐hexadecenal (1, 2) (genuine pheromone) in a 100‐ng dose against the male yellow peach moth, Dichocrocis punctiferalis.
Reaktionssteuerung durch die Struktur eines Phasentransfer‐Katalysators bei Tribrommethyl‐Anion‐/Dibromcarben‐Umsetzungen
Authors: V. Dehmlow Eckehard , Wilkenloh Jürgen 
Published: July 2007

Control of Reactions with Tribromomethyl Anions/Dibromocarbene by the Nature of the Phase Transfer CatalystConversion of (substituted) allyl bromides with bromoform/sodium hydroxide/phase transfer catalyst may be directed towards dibromocarbene addition or substitution by tribromomethyl anion by choice of the catalyst. The observed effects (addition: substitution in the primary step variable between maximally 92:1 and 1:91) are by far the largest reported for specific catalyst influences. Small, hard cations favor the carbene route, sterically shielded and highly delocalized ones favor the substitution process.
Über Pyridinium‐N‐phenolat‐Betaine und ihre Verwendung zur Charakterisierung der Polarität von Lösungsmitteln, XIV. Versuche zur Herstellung eines chiro‐solvatochromen Pyridinium‐N‐phenolat‐Betainfarbstoffs
Authors: Reichardt Christian , Wilk Martina 
Published: July 2007

Pyridinium N‐Phenoxide Betaines and Their Application for the Characterization of Solvent Polarities, XIV. — Attempted Synthesis of a Chiro‐Solvatochromic Pyridinium N‐Phenoxide Betaine DyeSynthesis and UV/VIS spectroscopic properties of the negatively solvatochromic, chiral, (S,S)‐configurated betaine dye 8 are described. There is a linear correlation between the ET′ values of 8 and the ET(30) values of the standard betaine dye 1 (Figure 1). Unfortunately, (S,S)‐8, dissolved in enantiomeric pure (R)‐ and (S)‐configurated alcohols and amines, does not show a measurable chiro‐solvatochromism (Table 2).
Polycyclische Aromatische Alkaloide, V. Synthese von 2‐Bromleptoclinidinon
Authors: Bracher Franz 
Published: July 2007

Polycyclic Aromatic Alkaloids, V. – Synthesis of 2‐Bromoleptoclinidinone4‐Bromo‐2‐nitroacetophenone (6) is selectively reduced to the amine 7 by Fe in aqueous acetic acid. Oxidative amination of quinolinequinone 8 with 7 gives 9. Acid‐catalyzed cyclization of 9, followed by anellation of a pyridine ring, gives the cytotoxic pentacyclic alkaloid 2‐bromoleptoclinidinone (3).
Glycosidation, 14. Stereoselective synthesis of acetal‐β‐glucosides by reaction of 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranose with enol ethers
Authors: Tietze Lutz F. , Lögers Michael 
Published: July 2007

AbstractAcetal‐glycosides are a new class of compounds which is of interest in the development of selective anticancer agents. Cytotoxic aldehydes and ketones may be released by enzymatic or acid‐catalyzed hydrolysis preferentially in the tumour tissue. An alternative synthetic route to acetal‐β‐glucosides 4 was developed in connection with these investigations. The acetyl‐protected acetal‐β‐glucosides 3a–h are obtained anomerically pure in 63–95% yield by reaction of 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranose (1) with an enol ether 2a–h in the presence of catalytic amounts of p‐toluenesulfonic acid in dry tetrahydrofuran at room temperature. Deacetylation with potassium carbonate in methanol gives the free acetal‐β‐glucosides 4a–h.
An improved preparation of 2‐methylene‐ and 2,3‐dimethylenecephalosporins
Authors: Gunda Tamas E. 
Published: July 2007

AbstractThe one‐step reductive cleavage and reduction of 3‐acetoxymethyl‐2‐methylenecephalosporin sulphoxides provides easy access to 2,3‐dimethylenecephems.
Unsymmetrically substituted furoxans, XII. Phenylfuroxancarboxylic acids and their derivatives
Authors: Fruttero Roberta , Ferrarotti Bruno , Serafino Anna , Gasco Alberto 
Published: July 2007

AbstractSynthesis and structure of the two isomeric furoxancarboxylic acids 3 and 14 and of a few of their derivatives 10–13, 15, 16 is reported. 1,3 Dipolar cycloaddition reactions of the product obtained by thermal decomposition of 4‐phenyl‐3‐furoxancarboxylic acid and thermal equilibration of furoxan derivatives are also discussed.
Approach to chiral vicinal diacylamines by Bamberger ring cleavage of substituted imidazoles
Authors: Altman Janina , Grinberg Mircea , Wilchek Meir 
Published: July 2007

AbstractRing cleavage of ethyl 3‐[4(5)‐imidazolyl]propanoate (1) with (−)‐menthyl chloroformate introduces chiral carbamate substituents on the double bond which, upon hydrogenation, induces preferred formation of ethyl (4S)‐4,5‐bis[(−)‐menthyl‐oxycarbonylamino]pentanoate (5) (5:1 ratio of diastereomers). The ring cleavage benzoylation product of (S)‐histidine methyl ester, with a chiral center in the side chain, gives rise to (2S,4R)/(2S,4S)‐2,4,5‐tribenzamidopentanoates (13, 14), in 2:1 ratio upon hydrogenation.
Synthesis of compounds with juvenile hormone activity, XXVIII. Synthesis of (−)‐juvenile hormone I, the antipode of the natural compound
Authors: Mori Kenji , Fujiwhara Mitsuhiko 
Published: July 2007

AbstractThe synthesis of the unnatural (10S,11R)‐(−)‐juvenile hormone I [(−)‐JH I, (−)‐1] is described.
Cycloadditionen, 18. 5‐Aminoisoxazole durch Cycloaddition von Nitriloxiden an Inamine
Authors: Himbert Gerhard , Kuhn Hildegard , Barz Michael 
Published: July 2007

Cycloadditions, 18. — 5‐Aminoisoxazoles by Cycloaddition of Nitrile Oxides to YnaminesTen differently substituted ynamines 1a–j react with five nitrile oxides 3a–e to give the 5‐aminoisoxazoles 4a–z. The stannyl‐substituted ynamine 1c furnishes the same compounds (e.g. 4a–d) by reaction with the hydroximoyl chlorides 2a–d. Two representatives of 4–b and p ‐ can be transformed into the corresponding 1‐azirine‐3‐carboxamides 6a and b.
Bonellin: Aufklärung der absoluten Konfiguration
Authors: Montforts Franz‐Peter , Müller Claudia Margrit , Lincke Anngret 
Published: July 2007

Bonellin: Determination of Its Absolute ConfigurationThe absolute configuration of bonellin (3), the physiologically active pigment of the marine echiuroid worm Bonellia viridis, has been established as (S) by ozonolytic degradation. Ozonolysis forms the imide 5 the configuration of which was confirmed by CD spectroscopic comparison with 5 from degradation of vitamin B12.
Reductive transformations of 5,6‐dihydro‐4H‐1,2‐oxazines: Synthesis of 4‐hydroxy ketoximes, N‐hydroxypyrrolidine derivatives, and other nitrogen‐containing compounds
Authors: Hippeli Claudia , Reißig Hans‐Ulrich 
Published: July 2007

Abstract6‐Siloxy‐substituted 1,2‐oxazines 1 are transformed into 4‐hydroxy ketoximes 2 by reduction with NaBH4 in ethanol. Reductive Beckmann rearrangement converts the oxime 2a into the 1,4‐amino alcohol 7. Diisobutylaluminum hydride (DIBAH) induces a novel reductive ring contraction of 1 to provide either N‐hydroxypyrrolidine derivatives 8 or nitrones 9. Other 1,2‐oxazines lacking the 6‐siloxy substituent are also studied under these reaction conditions. Catalytic hydrogenolysis either gives the acyclic amine 16 or it stops at the stage of the proline derivative 21. Mechanistic features of these synthetically valuable transformations are discussed.
Reaktion von 2,3,4‐Tri‐O‐acetyl‐α‐L‐rhamnopyranosylbromid mit ethanolischer Trimethylamin‐Lösung
Authors: Bognár Rező , Farkas István 
Published: July 2007

Reaction of 2,3,4‐Tri‐O‐acetyl‐α‐L‐rhamnopyranosyl Bromide with an Ethanolic Solution of TrimethylamineReaction of 2,3,4‐tri‐O‐acetyl‐α‐L‐rhamnopyranosyl bromide (1) with an ethanolic solution of trimethylamine yielded 2,3‐di‐O‐acetyl‐1,2‐O‐(1‐ethoxyethylidene)‐β‐L‐rhamnopyranose (2) instead of 1,4‐Anhydro‐2,3‐di‐O‐acetyl‐α‐L‐rhamnopyranose (3) as was earlier described in the literature. The structure of compound 2 was established by analysis and spectroscopical data.
Synthese von (R)‐Lasiodiplodin aus Polyhydroxybuttersäure
Authors: Braun Manfred , Mahler Ulrike , Houben Sabine 
Published: July 2007

Synthesis of (R)‐Lasiodiplodin from Polyhydroxybutyric AcidThe twelve‐membered macrolide (R)‐lasiodiplodin (1), a fungal metabolite of Botrysdiplodia theobromae, has been synthesized in a nine‐step procedure. (R)‐1,3‐Butanediol (6), which is easily available by reductive depolymerization of the biopolymer polyhydroxybutyric acid (PHB), proves itself as a suitable enantiomerically pure building block.
Solanum alkaloids, 117. Synthesis of the steroid alkaloid soladunalinidine and other 5α‐spirosolan‐3‐amines
Authors: Quyen Le Thi , Ripperger Helmut , Schreiber Klaus 
Published: July 2007

AbstractThe steroid alkaloid soladunalinidine [5α‐tomatidan‐3β‐amine, (25S)‐5α,22βN‐spirosolan‐3β‐amine, 2], isolated from Solanum dunalianum, is synthesized from tomatidine (5α‐tomatidan‐3β‐ol, 1) via 5α‐tomatidan‐3‐one (4) and its oxime 5 which is reduced to 2 as well as to its ring‐E‐opened (22S) and (22R) dihydro products 6 and 9, the N(22,26)‐chloro‐N(3)‐(2‐hydroxy‐benzylidene) derivatives 8 and 11 of which are recyclized to N(3)‐(2‐hydroxybenzylidene)soladunalinidine (3). The 5α‐spirosolan‐3‐amines stereoisomeric at C‐22 and C‐25, 5α‐solasodan‐3α‐amine (13) and ‐3β‐amine (15), are obtained in an analogous sequence of reactions from soladulcidine (5α‐solasodan‐3β‐ol, 12).
Spectroscopic studies of the solvent polarities of room‐temperature liquid ethylammonium nitrate and its mixtures with polar solvents
Authors: Herfort Ina‐Maria , Schneider Hermann 
Published: July 2007

AbstractThe maximum wavelength of the solvatochromic absorption band of Dimroth‐Reichardt's dye I, 2,4,6‐triphenylpyridinium N‐4‐(2,6‐diphenylphenoxide) betaine, has been determined at 25°C from the ultraviolet‐visible spectra of solutions of this dye in ethylammonium nitrate (EAN) and its mixtures with several polar solvents. The related molar transition energy, ET(30) in kcal/mol, of the long‐wavelength absorption band increases sharply, when EAN is dissolved at low concentrations in the various solvents. The pronounced blue shift of the absorption band is attributed to the hydrogen‐bond interaction between the ethylammonium cation and the ground state of the betaine molecule.
Enzym‐katalysierte Reaktionen, 7. Enantioselektive Veresterung racemischer Cyanhydrine und enantioselektive Hydrolyse oder Umesterung racemischer Cyanhydrinester mittels Lipasen
Authors: Effenberger Franz , Gutterer Beate , Ziegler Thomas , Eckhardt Elisabeth , Aichholz Reiner 
Published: July 2007

Enzyme‐Catalyzed Reactions, 71). – Enantioselective Esterification of Racemic Cyanohydrins and Enantioselective Hydrolysis or Transesterification of Cyanohydrin Esters by LipasesPure cyanohydrin enantiomers (S)‐1/(R)‐1 and their O‐acyl derivatives (R)‐3/(S)‐3 are obtained from three different lipasecatalyzed reactions: i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective acylation of racemic cyanohydrins 1, iii) enantioselective transesterification of 3 with primary alcohols. Both the cyanohydrin esters and the free cyanohydrins (which are prone to racemization) are isolated as enantiomers with high optical purity on a preparative scale. Hydrolysis of the racemic butyrates 3b, e with Candida cylindracea lipase and pseudomonas sp. lipase, respectively, for example, affords the free (S)‐cyanohydrins (S)‐2‐hydroxypentanenitril [(S)‐1a] and (S)‐mandelonitrile [(S)‐1b)] in high yield with 97 and 96% ee, respectively. (S)‐1a is obtained with the same optical purity by candida sp. lipase‐catalyzed transesterification of 3b with 1‐octanol.