bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Cyclosporine. Part II. Synthesis of Boc‐D‐Ala‐MeLeu‐MeLeu‐MeVal‐OH, a part of the peptide sequence of cyclosporine, by different strategic ways and synthesis of its isomers Boc‐D‐Ala‐MeLeu‐D‐MeLeu‐MeVal‐OH, Boc‐D‐MeLeu‐DMeVal‐OH, and Boc‐D‐Ala‐MeLeu‐MeLeu‐D‐MeVal‐OH as reference compounds
Authors: Wenger Roland M. 
Published: December 2004

AbstractBoc‐D‐Ala‐MeLeu‐MeLeu‐MeVal‐OH (DLLL) and its isomers DLDL, DLDD and DLLD were synthesized using several different strategic approaches and a modification of the mixed pivalic anhydride method for carboxyl activation. Alternatively, the tert‐butoxy‐carbonyl (Boc) or benzyloxycarbonyl (Z) amino‐protecting groups and the benzyloxy (OBzl) or tert‐butoxy (OtBu) carboxyl‐protecting groups were used to protect the reacting peptides. By monitoring the reaction temperature, it was possible to synthesize, starting from the tripeptide DLL as peptide model, either the tetrapeptide DLLL (−20°) or the tetrapeptide DLDL (+20°), selectively. Using 1H‐NMR spectroscopy to follow the mixed pivalic anhydride formation of the DLL‐ and DLD‐tripeptides, it could be shown that anhydride formation is strongly dependent on the temperature. It is slow at −20° (several hours) and fast at +20° (20 to 40min). The isomerization of the DLL‐anhydride to the more stable DLD‐anhydride can be reduced to a minimum by working at −20°, while this isomerization proceeds to near completion at +20°.
Neue Coleone und Royleanone aus Coleus somaliensis S. MOORE
Authors: Matloubi‐Moghadam Firouz , Rüedi Peter , Eugster Conrad Hans 
Published: December 2004

Novel Coleons and Royleanones from Coleus somaliensis S. MOOREReexamination of the fraction of polar diterpenoids from the title plant, in addition to the previously identified compounds of Scheme 1 [2] [3], leads to the isolation of (15S)‐coleon D (8), the abeo‐royleanones 9–11 and the spirocoleons 12–17. Crystalline (15S)‐coleon I (3a) is characterized.
Kopsirachin, ein ungewöhnliches Alkaloid aus der Apocynaceae Kopsia dasyrachis Ridl. 189. Mitteilung über organische Naturstoffe
Authors: Homberger Katharina , Hesse Manfred 
Published: December 2004

Kopsirachine, an Unusual Alkaloid from the Apocynaceae Kopsia dasyrachis Ridl.From the leaves of Kopsia dasyrachis Ridl. a new type of alkaloid, kopsirachine (1), built up from catechin (2) and skytanthine (3) has been isolated. The structure elucidationis based on spectral and chemical evidence. Oxidative cleavage of its derivative 4 with KMnO4 afforded veratric acid wich was identified as its methylester by comparison with an authentic sample. Pyrolysis of 1 yielded δ‐skytanthine (3). The stereochemistry of the skytanthine substituents in 1 could not yet be established.
2′‐Nitro‐2′‐propen‐1′‐yl 2,2‐Dimethylpropanoate (NPP), A Multiple Coupling Reagent
Authors: Seebach Dieter , Konchel Paul 
Published: December 2004

AbstractThe title compound 1 (NPP) is prepared from formaldehyde, nitromethane, an pivaloyl chloride. It is shown to be a versatile nitroallylating reagent combining with nucleophiles as different as anilines, indoles, enolates, and organolithium compounds. This is documented by ca. 40 examples (2–30). The mechanism of the reaction is discussed. Some examples of addition of two different nucleophiles to the C3‐moiety of NPP are described (35‐46). This demonstrates the usefulness of NPP as a multiple coupling reagent for convergent syntheses, also of products not containing nitro groups ((Scheme 4)).
Reaction of alcohols and amines with diacetyldihydrofluorescein (DADF): Conversion into erythrosine‐derivatives on TLC‐plates by ammonia and iodine vapors
Authors: Sharma Paam N. , Brossi Arnold 
Published: December 2004

AbstractReaction of decetylcolchicine (2) and colchifoline (3) with diacetyldihydrofluorescein (1, DADF) afforded the corresponding amide and ester derivatives, converted on TLC‐plates after exposure to ammonia and iodine vapors into red colored pigments. This reaction, also observed with DADF‐derivatives of codeine, quinine and mescaline is highly sensitive. The red pigment produced from the DADF‐ester (6) of colchifoline formed by te ammonia‐iodine treatment is the corresponding erythrosine ester derivative. DADF emerges from these investigations as a useful reagent to detect alcohols and amines in crude mixtures and for dye labeling.
Percolative Phenomena in Microemulsions of the ‘One‐Component Macrofluid’ Type
Authors: Eicke Hans‐Friedrich , Hilfiker Rolf , Holz Manfred 
Published: December 2004

AbstractThe temperature dependence of the water self‐diffusion coefficients (D), as well as those of low‐ and high‐field (stationary and time‐dependent) specific conductivities (K), have been determined in the percolation regime of ternary mixtures of water, AOT, and oil. For the first time a pronounced similarity in the behavior of D and κ was detected giving instructive hints about the large variations in the specific conductivities of these systems. Results from kinetic and stationary experiments are consistent with a network‐structure model of micro phases in the percolation regime in which the micro phases retain their discrete character.
The mass spectra of organic compounds. 7th Communication. 4,4‐Dimethyl‐1‐pentene
Authors: Marques José Carlos Antunes , Falick Arnold , Heusler Andréas , Stahl Daniel , Tecon Pierre , Gäumann Tino 
Published: December 2004

AbstractLoss of CH, CH4, C2H4, C3H, C3H6 and C3H7 from the molecular ions of a number of 13C‐labeled analogs of 4,4‐dimethyl‐1‐pentene was studied both in normal (source) 70‐eV electron impact (EI) spectra dn in metastable spectra. For loss of CH in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C‐1 (16%) and C‐3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C‐1 or C‐3 are lost with any other C‐atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C‐1 and C‐3 being 6%. If C‐1 seems to these two positions become completely equivalent in the metastable time range. The T‐values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C‐1, C‐2 and C‐3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H appears to be the the result of consecutive loss of CH and C3H4, rather than a one‐step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H and C5H secondary ions occurs in an essentially random fashion.
Ammonia chemical ionization mass spectrometry of alcohols: Structural, stereochemical, molecular‐size and temperature effects
Authors: Gülaçar Fazil O. , Mermound François , Winkler F. Johann , Vuchs Armand 
Published: December 2004

AbstractAmmonia chemical ionization (CI) mass spectra of various open‐chain, cyclic and unsaturated C5‐ to C10‐alcohols were obtained at source temperatures ranging from 60° to 250°C. The reactivity of the ammonia adduct ion MNH and its fragmentation channels are characteristic for substrate structure. Although strongly temperature‐dependent, the spectra give nevertheless information on the OH‐group environment as well as on the C‐skeleton at any source temperature. Primary, secondary and tertiary alcohols as well as allylic and simple olefinic alcohols can be distinguished by their spectra, which show ammonium adduct ions [MNH4]+, adduct dehydrogenation ions [MNH4‐H2], ammonium substitution ions [MNH4‐H2O]+ and [M‐OH]+‐ions as the main characteristic peaks. Moreover, konfigurational assignments of stereoisomeric alcohols are possible for larger substrate‐size and source‐temperature ranges than with isobutane CI mass spectrometry. Homologous M NH‐ions show molecular‐size control of fragmentation and linear MNH‐ions are less stable than branched isomers due to incomplete energy randomization.
Synthesis of cyclosporine. Total syntheses of ‘cyclosporin A’ and ‘cyclosporin H’, two fungal metabolites isolated from the species Tolypocladium inflatum GAMS
Authors: Wenger Roland M. 
Published: December 2004

AbstractThe heptapeptide H‐MeBmt‐Abu‐Sar‐MeLeu‐Val‐MeLeu‐Ala‐OBzl (20) was synthesized for coupling with the previously described cyclosporine tetrapeptide sequence Boc‐D‐Ala‐MeLeu‐MeVal‐OH (21). The product of the coupling, the undecapeptide Boc‐D‐Ala‐MeLeu‐MeLeu‐MeVal‐MeBmt‐abu‐Sar‐MeLeu‐Val‐MeLeu‐Ala‐OBzl (22), was then deprotected and cyclized to cyclosporine (1).The tetrapeptide diastereoisomer Boc‐D‐ala‐MeLeu‐MeLeu‐D‐MeVAl‐OH (23) could also be used as a starting material to produce selectively the desired undecapeptide 22. In this case, the N‐methyl‐D‐valine unit, was selectively isomerized to the L‐from by using the appropriate condensing agent. The diastereoisomeric undecapeptide Boc‐D‐ala‐MeLeu‐MeLeu‐D‐MeVal‐MeBmt‐Abu‐Sar‐MeLeu‐Val‐MeLeuAla‐OBzl (24) was also synthesized starting from 21 by using the mixed pivalic anhydride method to selectively invert the configuration of the N‐methyl‐L‐valine. The structure of the undecapeptide 24 was confirmed by deprotection and cyclization to ‘cyclosporin H’, a natural product known to have the structure [D‐MeVal11]cyclosporine (2).
1,3‐Dipolare Cycloadditionen von Nitrilium‐Betainen mit 4,4‐Dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thion
Authors: Büchel Thomas , Prewo Roland , Bieri Jost H. , Heimgartner Heinz 
Published: December 2004

1,3‐Dipolar cycloadditions of Nitrilium Betaines with 4,4‐Dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thioneBenzonitrile ylides, imines, and oxides undergo smooth 1,3‐dipolar cycloaddition reactions with the exocyclic, C,S‐double bond of 4,4‐dimethyl‐2‐phenyl‐2‐thiazolin‐5‐thione (1), yielding heterocyclic spiro‐compounds. The structure of the cycloadducts 5c, 5c′, and 3f (Fig.) have been established by x‐ray structure analysis.With the benzonitrile ylides, the two regioisomeric cycloaddition modes have been observed, depending on the substituents of the ylide‐C‐atom. It is questionable, whether the reaction of 1 and the oxazaphosphol 8 (Schemes 8 and 13) proceeds via the corresponding nitrile ylide as an intermediate.
The Circular Dichroism of 5,6‐Dimethylidene‐2‐bicyclo[2.2.n]alky Esters. Chiral Exciton Coupling between Benzoate and Exocyclic s‐cis‐Butadiene Chromophores
Authors: Zhichen Zou , Carrupt Pierre‐Alain , Vogel Pierre 
Published: December 2004

AbstractThe optically pure aryl‐substituted 5,6‐dimethylidene‐2‐bicyclo[2.2.1]heptyl benzoates 12–21 were prepared; their UV absorption and CD spectra are reported. The (−)‐(1S,2S)‐esters 17–21 with carbonyl groups in endo‐position exhibit typical excitonsplit Cotton effects whereas the corresponding (−)‐(1S,2R)‐esters 12‐16 with carbonyl groups in exo‐position do not present such effects. The chiral exciton coupling between the exocyclic diene and a remote p‐substituted benzoate chromophore can be used for unambiguous assignment of the absolute configuration of 5,6‐dimethylidene‐2‐endo‐bicyclo[2.2.1]heptyl derivatives. The method is applied to establish the absolute configuration of 5,6‐dimethylidene‐2‐exo and ‐2‐endo‐bicyclo[2.2.2.]octyl p‐bromobenzoates (−)‐24 and (−)‐25.
Photochemistry of 2‐(Trifluoromethyl) cyclohexanone
Authors: Semisch Christoph , Margaretha Paul 
Published: December 2004

AbstractThe photochemical behaviour of the title compound 1a is compared to that of the non‐fluorinated parent ketone 2‐methylcyclohexanone (1b). Substitution of the CH3‐ group on C(2) by a trifluoromethyl group strongly enhances 2H‐ and RH‐ reduction product formation in cyclohexane or 2‐propanol and oxetane formation in the presence of 2‐methylpropene as olefinic component. Under all these conditions 1b exclusively undergoes a‐cleavage, a process observed for 1a only in non‐reducing solvents as benzene or tert‐butyl alcohol.
NMR Conformational Study of Aminoalkylbenzamides, Aminoalkyl‐o‐anisamides, and Metoclopramide, a Dopamine Receptor Antagonist
Authors: Anker Lucien , Van De Waterbeemd Han , Testa Bernard , Lauterweiin JÜRgen 
Published: December 2004

AbstractThe conformational behaviour of metoclopramide, a neuroleptic benzamide, and model compounds was investigated byt 1 H‐NMR spectroscopy. An intramolecular amide‐methoxy H‐bond is shown to exist in CDCl3‐solution, but not in D2O‐solution, independently of the length and protonation state of the basic side‐chain. This H‐bond creates a virtual cycle which may be a key feature for the binding of neuroleptic benzamides to the dopamine receptor. The conformational behaviour of the aminoethyl side‐chain is shown to be markedly condition‐dependent. For metoclopramide and its analogues in their protonated form, the gauche‐ and trans‐ rotamers have identical energies in D2O‐as well as in CDCl3‐solutins. For the non‐protonated molecules, the trans‐rotamer is favoured in D2O‐solutin, while the gauche‐rotamer is favoured in CDCl3‐solution (ΔG°≃|0.5|kcal/mol in both cases). The side‐chain conformation of neuroleptic benzamides is discussed in terms of receptor affinity.
Stereospecific, R2AlCl‐Promoted Intramolecular Ene Reaction of a 1,6‐Dienoate: Evidence for a Concerted Mechanism
Authors: Oppolzer Wolfgang , Mirza Sohail 
Published: December 2004

AbstractTreatment of the 83%‐trans‐13CH3‐labelled 1,6‐dienoate 7 with Et2AlCl at–78° provided in high yield the ene product 9 containing 83% 13C localized in the olefinic C(8)‐methylene group. Accordingly, H‐transfer occurs exclusively from the trans‐methyl group of 7, consistent with a concerted ene process 7 9 thereby ruling out an intermediate cation 8 (Scheme 4).
Asymmetric Aldol Condensation of 1‐Naphtol and Pyruvates in the Presence of Lewis Acids Preliminary Communication
Authors: Piccolo Oreste , Filippini Lucio , Tinucci Laura , Valoti Ermanno , Citterio Attilio 
Published: December 2004

AbstractLewis acids catalyze teh condensation of methyl pyruvate and l‐naphtol to give menthyl 2‐hydroxy‐2‐(l‐hydroxy‐2‐naphtyl)propionate in a ratio of up 96:4 in favor of the levorotatory diastereoisomer. Epimerization, at 25°C for five days, occurs on benzylic carbon atom to give a 30:70 mixture enriched with the dextrorotatory isomer.
Absolute Conformation and Configuration of (2S, 3S)‐3‐Acetoxy‐5‐(dimethylaminoethyl)‐2‐(4‐methoxyphenyl)‐2,3‐dihydro‐1,5‐benzothiazepin‐4(5H)‐one Chloride (Dilthiazem Hydrochloride)
Authors: Kojić‐Prodić Biserka , Ružić‐Toroš ŽIva , Šunjić Vitomir , Decorte Enio , Moimas Flavio 
Published: December 2004

AbstractResolution of racemic cis‐3‐(2‐aminophenylthio)‐2‐hydroxy‐3‐(4‐methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)‐ and (−)‐5, as well as their cyclization to enantiomeric 1,5‐benzothiazepines (+)‐ and (−)‐1, are described. X‐Ray single‐crystal analysis reveals (2S, 3S) absolute configuration of (+)‐1 on the basis of tentative comparison of CD data with those for the 1,4‐benzodiazepine derivative (+)‐8 of known absolute configuration.
Synthese und Struktur von Zink‐Komplexen von 2‐Amino‐1‐azetinen
Authors: Stierli Friedrich , Prewo Roland , Bieri Jost H. , Hemigartner Heinz 
Published: December 2004

Synthesis ad Structure of Zinc Complexes of 2‐Amino‐1‐azetinesThe 2‐dimethylamino‐3,3‐dimethyl‐1‐azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1‐benzhydryl‐azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X‐ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X‐ray diffraction analysis too.
A Lipophilic Derivative of Vitamin B12 as Selective Carrier for Anions
Authors: Schulthess Peter , Ammann Daniel , Simon Wilhelm , Caderas Christian , Stepánek René , Kräutler Bernhard 
Published: December 2004

AbstractIncorporation of the lipophilic Co(III)‐cobyrinate octadecyl‐cobester 1 and of its ionic aqua‐cyano perchlorate derivative 2 into poly(vinyl chloride)/bis(1‐butylpentyl) adipate liquid membranes induces a selectivity, measured potentiometrically, of about 103 for SCN− an NO with respect to CI−, but only of about 4 for ClO vs. CI−. This is in contrast to classical anion‐exchanger membranes, which exhibit a selectivity sequence ClO > SCN− ≫ NO > Cl− in accordance with the Hofmeister, series. The Co(III)‐corrins 1 and 2, when components in solvent polymeric membranes, undergo exchange of axial ligands an behave as highly selective carriers fof SCN− and NO.
Crystal and Molecular Structure of the 4:3 Complex between Lanthanum Nitrate and Pentaethyleneglycol Dimethyl Ether
Authors: Bünzil Jean‐Claude C. , Pfefferlé Jean‐Marc , Ammann Bruno , Chapuis Gervais , Zuniga F.‐Javier 
Published: December 2004

AbstractThe crystal and molecular structure of [La(NO3)3]4(C12H26O5)3 has been determined from low‐temperature single‐crystal X‐ray diffraction data. The complex crystallizes in the monoclinic space group I2 with Z = 2. Lattice parameters at 150 K are a = 12.234 (6) Å, b = 11.105 (5), c = 26.613 (9), β = 90.65 (4)°. The structure was solved by Patterson and Fourier techniques and refined to a conventional RF‐value of 0.068. The compound contains three dinitrato complex cations [La(NO3)2C12H26O6]+ with 10‐coordinate lanthanum ions and one hexanitrato anion, [La(NO3)6]3−, with a 12‐coordinate La(III)‐ion. One complex cation has a C2‐symmetry while the two others, which are crystallographically equivalent, have no symmetry and contain a disordered ligand molecule. The polyther adopts a ring‐like conformation in all the complex moietis. The LaO(nitrate) distances lie in the ranges 2.52–2.53 and 2.49–2.62 Å, with average values of 2.53 (7) and 2.56 (6) Å, respectively, fo the species with C2‐ and C1‐symmetry; the LaO(ether) bond lengths lie int he range 2.54–2.79 Å (average: 2.6 (1)) for the C2‐moiety and their mean value amounts to 2.6 (2) for the disordered species. The hexanitrate has a C2‐symmetry and the LaO distances range between 2.56 and 2.67 Å with an average value fo 2.64 (4) Å. The effective ionic radii of the 10‐ and 12‐coordinate La(III) ions are estimated as 1.28 and 1.33 Å, respectively.
Experiments on the Total Synthesis of Lysolipin I. Part I. On Configuration and Conformation of 5‐Substituted 1,2,3,4,4a,9,10,10a‐Ocathydrophenanthrene‐4,9‐diones
Authors: Duthaler Rudolf O. , Mathies Peter , Petter Walter , Heuberger Christoph , Scherrer Veronica 
Published: December 2004

AbstractThe substituted 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene‐4,9‐dione 2, synthesized from the cyclohexanone 8 and quinone 11 (Scheme 2), was found by X‐ray analysis adn 1H‐NMR studies to be the isomer with cis‐junction of the saturated rings. The cis‐fusion could also be determined from the 1H‐NMR data of the related compound 17 (Scheme 4), which was previously considered to be trans‐fused. In contrary to previous argumentations, the interaction of the C(4)‐carbonyl O‐atom of trans‐fused octahydrophenanthenes is more severe with a 5‐methoxy than with a 5‐methyl substituent.
13C‐NMR spectra of cannbinoids. Part 2. Side‐chain substituted tetrahydrocannabinols and synthetic intermediates
Authors: Franke Ingo , Schmidt Burkhard , Dietrich Wolfgang , Binder Michael 
Published: December 2004

AbstractThe 13C‐NMR spectra of eight semi‐synthetic side‐chain substituted cannabinoids and of eight synthetic intermediates were analyzed in detail. Assignments of the signals are based on their chemical shifts, splitting patterns in 1H‐off‐resonance decoupling experiments, incremental calculations, and model considerations.
Interactions between Functional Groups. Part II. Structure of the 2‐Dimethylaminobenzenediazonium Cation: Retention of Planarity Despite Excessive Steric Crowding
Authors: Wallis John D. , Dunitz Jack D. 
Published: December 2004

AbstractThe crystal structure of 2‐dimethylaminobenzenediazonium tetrafluoroborate has been determined at 183 K by X‐ray diffraction. The cation is very nearly planar, the strong steric interaction between the ortho‐groups being diminished by in‐plane angular distoritions.
Oxidative Cyclopropanol Opening by Cob(III)alamin
Authors: Wan Terence S. , Fischli Albert 
Published: December 2004

AbstractStarting from the cyclopropanol 2, the isomeric cyclopropanol 4 and the β, γ‐unsasturated aldehydes 7 and 8 have been produced by a cobalamin‐dependant transformation. In traces, the two acetoxycyclopropanes 3 and 6, the saturated aldehydes 5 and 11 and the β,γ‐unsaturated aldehyde 9 could be detected (cf. Structural Formulae and Table). Starting from 4 the same products in a rather similar distribution were obtained. The isomerization 2⇄4 as well as the transformations leading to 7,8, and 9 are shown to be mediated by cob(III)alamin (1(III)). The results are explained on the basis of rearranging Co‐complexes. The migrations might be driven by the electrophilic nature of the central Co(d6)‐atom.
Functionalized Cycloheptanes from Bicyclo[4.2.1]nonanes
Authors: Huston Rima , Rey Max , Dreiding André S. 
Published: December 2004

AbstractSeveral oxidative, reductive and C,C‐cleavage reactions were performed starting from the three bicyclo[4.2.1]nona‐3,7‐diene‐2‐one derivatives 1, 5 and 18. The oxidations were selective and led to the diols 2,8 and 9, and the epoxides 6,9, and 20. The reductions were selective only in the case of 20 21; otherwise they led to mixtures of the alcohols 10 and 11, and of the dienes 14 and 15. The periodate ring cleavages afforded the functionalized cycloheptane derivatives 3, 12, 13 and 16. Configurational assignments were made on the basis of detailed 1H‐NMR and X‐ray analysis of 20.
Drüsenfarbstoffe aus Labiaten: Die polaren Diterpenoide aus Plectranthus argentatus S. T. BLAKE
Authors: Alder Alfredo Carlos , Rüdi Peter , Eugster Hans 
Published: December 2004

AbstractPolar Diterpenoids from Leaf‐Glands of Plectranthus argentatus S. T. BLAKEFrom the red leaf‐glands of the Australian Plectranthus argentatus the following novel diterpenoids were isolated: coleon‐U‐quinone (1), 8α,9α‐epoxycoleon‐U‐quinone (3), 6β‐formyloxy‐7α‐hydroxyroyleanone (7), and 5,6‐dihydrocoleon U (10), besides the already known compounds 6β, 7α‐dihydroxyroyleanone (4), 7α‐acetoxy‐6β‐hydroxyroyleanone (5), and 7α‐formyloxy‐6β‐hydroxyroyleanone (6). Epoxydation of 1 by perborate led in 32% yield to the epoxyquinone 3.
The synthesis and transition temperatures of benzoate ester derivatives of 2‐fluoro‐4‐hydroxy‐and 3‐fluoro‐4‐hydroxybenzonitriles
Authors: Kelly Stephen M. 
Published: December 2004

AbstractThe synthesis and the liquid‐crystal temperatures of sixty 4‐cyano‐2‐fluorophenyl and 4‐cyano‐3‐fluorophylen 4‐substituted benzoates are described. The nematic‐isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing an H‐atom in place of the F‐substituent. In several instances, the clearing points of the F‐substiuted‐phenyl esters are higher than those of the non‐substituted‐phenyl esters. The nematic ranges of several of the new esters are markedly broader than those of the analogous non‐F‐substituted‐phenyl esters.
Synthese von 2,3‐unsubstituierten, N‐acylierten Indolen durch sigmatrope[3,3]‐Umlagerung von O‐Vinyl‐N‐phenylhydroxylaminderivaten
Authors: Martin Pierre 
Published: December 2004

AbstractSynthesis of 2,3‐Unsubstituted N‐Acylindoles by [3,3]‐Rearrangement of the N‐Phenyl‐O‐vinylhydroxylamine DerivativesSummary, Treatment of N‐phenylhydroxamic acids with vinylacetate in the presence of Li2PdCl4 affords 2,3‐unsubstituted N‐acylindoles via hetero‐Cope‐rearrangement of the intermediate N‐O‐vinylhydroxylamine derivatives.