bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thiocarbonyl‐imide aus der Umsetzung von 2,2,4,4‐Tetramethyl‐3‐thioxocyclobutanon mit Aryl‐aziden
Authors: Mlostoń Grzegorz , Romański Jaroslaw , Linden Anthony , Heimgartner Heinz 
Published: December 2004

Thiocarbonyl Imides from the Reaction of 2,2,4,4‐Tetramethyl‐3‐thioxocylobutanone and Aryl AzidesReaction of 2,2,4,4‐tetramethyl‐3‐thioxocylobutanone (6) and 4‐methoxyphenyl, phenyl, and 4‐nitrophenyl azide (7a–c, respectively), at 80°, leads to the 11‐aryl‐5,10‐dithia‐11‐azadispiro[3.1.3.2]undecane‐2,8‐diones 8a–c (Scheme 3), respectively, in 67–83% yield. The structure of 8b has been established by X‐ray crystallography. The formation of the products may be explained via an intermediate thiocarbonyl imide of type D (Scheme 4), generated by the 1,3‐dipolar cycloaddition of the aryl azide with the CS bond of 6 and elimination of N2.
The Crystal Structure of C70 · 6(S8) at 100 K
Authors: Bürgi Hans Beat , Venugopalan Paloth , Schwarzenbach Dieter , Diederich François , Thilgen Carlo 
Published: December 2004

AbstractThe crystal structure of C70 · 6(S8) at 100 K shows C70 to be ordered and the S8 molecules to be partially disordered. The symmetry of C70 is D5h to within experimental accuracy.
Stereoselectivity of the Radical Reductive Alkylation of Enamines: Importance of the Allylic 1,3‐Strain Model
Authors: Schubert Serge , Renaud Philippe , Carrupt Pierre‐Alain , Schenk Kurt 
Published: December 2004

AbstractRadical addition to enamines using Bu3SnH as reducing agent are reported (Schemes 2 and 4). The diastereoselectivity of these reactions was examined in different systems (Tables 1 and 2). Enamines derived from cyclic ketones such as cyclohexanone were alkylated with high diastereoselectivity with preferential formation of the cis‐disubstituted cycloalkanes. In acyclic systems such as enamines derived from propiophenone and diethyl ketone, moderate to high stereoselectivities were observed in the H‐abstraction step. A model based principally on minimization of allylic 1,3‐strain (A1,3 strain) was deduced from the experimental results and semi‐empirical (AM1) calculations.
Transition Metal‐Diene Complexes in Organic Synthesis. Part 15. Iron‐mediated total synthesis of carbazomycin A and B
Authors: Knölker Hans‐Joachim , Bauermeister Michael 
Published: December 2004

AbstractWe developed a very efficient methodology for the synthesis of the antibiotics carbazomycin A (1) and B (2) by oxidative coupling of cyclohexa‐1,3‐diene and the corresponding arylamine 10 (Scheme 5 and Schemes 7 and 9, resp.). The overall process is achieved by a consecutive Fe‐induced formation of the CC and the CN bond. The major benefit of our Fe‐mediated carbazole synthesis is that the coupling process is possible with fully functionalized arylamines 10. Therefore, highly convergent syntheses of carbazole alkaloids are feasible, and linear multistep sequences as required by using classical procedures are avoided. The total synthesis of 1 and 2 emphasizes this characteristic feature of the Fe‐mediated construction of the carbazole framework.
Novel Access to Furan‐3‐thiols and Derivatives, Impact Meat‐Flavor Compounds
Authors: Huber Ulrich A. , Bergamin Desirée 
Published: December 2004

AbstractA versatile process for the preparation of a number of 3‐thio‐substituted furans 1–4 is described. These products have very low odor thresholds and are thus potent flavor compounds. Fur‐3‐yl thiocyanates 10a, b as well as other S‐containing analogues (2b, 7a, b, and 8) were prepared by a Michael‐type addition of thiocyanic acid, thioacetic acid, alakanethiols, and sodium thiosulfate to alkynones 6 or 15, followed by cyclization (Schemes 3 and 4). The thiocyanates 10a, b were converted to mixed disulfides 3, symmetric disulfides 4, thioethers 2, and thiols 1, using ‘hard’ or ‘soft’ nucleophiles or reducing agents, respectively (Scheme 6).
Catalytic Cyclophanes. Part IX. A Thiazolio‐cyclophane as Model for Pyruvate Oxidase and One‐Pot Synthesis of Aromatic Esters by Electrochemical Oxidation of Aldehydes Mediated by Bis(coenzyme) Catalysis
Authors: Tam‐Chang Suk‐Wah , Jimenez Leslie , Diederich François 
Published: December 2004

AbstractMacrocycle 3 with a hydrophobic cavity and an appended thiazolium ring is prepared following a novel synthetic sequence to monofunctionalized cyclophanes. Although the thiazolium ring of 3 prefers to be located in the cyclophane cavity, it could be displaced with low energetic costs by benzene and naphthalene guests which form stable 1:1 inclusion complexes with 3 in protic solvents. Initial rate studies show that 3 is a pyruvate‐oxidase mimic and catalyzes the oxidation of aromatic aldehydes to carboxylic acids in aqueous solution. Cyclophane 3 also catalyzes the conversion of aromatic aldehydes to the corresponding esters in alcoholic solvents. The supramolecular catalyst 3 exhibits enzyme‐like saturation kinetics, large turnover numbers, as well as high reaction and substrate selectivity, and it is far superior to the non‐macrocyclic catalysts 4 and 5 which lack a substrate binding site. Following cyclic voltammetric investigations of the redox behavior and stability of thiazolium ions, a new one‐pot electrochemical synthesis of aromatic esters is developed: Aromatic esters are prepared efficiently by indirect electrochemical oxidation of the corresponding aldehydes in alcoholic solvents, mediated by two coenzymes, the thiazolium ions 3 or 5 and flavin 21. At the extraordinarily low working electrode potential of −300 mV (vs. Ag/AgCl), high yields of the esters are obtained with high current efficiencies and high turnovers of the catalysts which are stable under the reaction conditions. The origin of the substrate and reaction selectivity, which is particularly pronounced in the supramolecular reactions catalyzed by 3, is analyzed.
Synthesis, Structure, and Antimalarial Activity of Tricyclic 1,2,4‐Trioxanes Related to Artemisinin
Authors: Jefford Charles W. , Velarde Javier A. , Bernardinelli Gérald , Bray Dorothy H. , Warhurst David C. , Milhous Wilbur K. 
Published: December 2004

AbstractTwo sets of tricyclic 1,2,4‐trioxanes containing the ABC (10, 11) and ACD ring portions (21, 22, 32, 33, 37, and 38) of artemisinin (1) were synthesized by successive photo‐oxygenation of appropriate enol‐ether precursors to 1,2‐dioxanes and inter‐ and intramolecular reaction with a carbonyl compound or oxo‐substituted side‐chain. The structures of 10, 21, and 22 were determined by X‐ray analysis. The anti‐malarial activity of all trioxanes, except 37 and 38, was evaluated in vitro against chloroquine‐sensitive and chloroquine‐resistant Plasmodium falciparum parasites. Trioxanes 11 and 21 were as active as artemisinin (1). It was found that neither the lactone function nor rings B and D of 1 were essential for activity. A possible pharmacophore for artemisinin‐like activity, which embodies a spirocyclopentane group attached to C(3) of 1,2,4‐trioxane, was proposed.
Rhodium(II)‐Catalyzed Decomposition of β,γ‐Unsaturated Diazo Compounds
Authors: Motallebi Shahrokh , Müller Paul 
Published: December 2004

AbstractThe RhII‐catalyzed decomposition of β,γ‐unsaturated diazo ketones 1 in the presence of MeOH leads via vinylogous Wolff rearrangement to γ,δ‐unsaturated esters 6 (Schemes 1 and 2). A modest asymmetric induction is achieved when the reaction is carried out with chiral tetrakis(pyrrolidinecarboxylato)‐ or tetrakis(oxazolidinonato)dirhodium(II) complexes. Vinyl and phenyl diazoacetates 11 and 20, respectively, or 1‐diazo‐3‐phenyl‐propan‐2‐one (25), when subjected to the same reaction conditions, react by OH insertion with MeOH (Schemes 3–5). In the absence of MeOH, phenyl diazoacetates 20 and 25 undergo intramolecular CH insertion to 22 and 26, respectively. Intramolecular CH insertion occurs with N‐aryldiazoamides 23 even in the presence of MeOH (Scheme 5).
Synthesis and Electron‐Diffraction Structure of all‐cis‐[5.5.5.5]Fenestrane
Authors: Brunvoll Jan , Guidetti‐Grept Régine , Hargittai Istvan , Keese Reinhart 
Published: December 2004

AbstractThe efficient synthesis of all‐cis‐[5.5.5.5]fenestrane (2) from the readily available intermediate 3 allowed the electron‐diffraction analysis of 2. This structure analysis revealed long CC bonds in the central C(C)4 fragment and a twist‐envelope conformation for the four cyclopentane substructures. The four bridgehead H‐atoms are in a synclinal rather than an ecliptic position with an approximate D2 symmetry of 2. Planarizing distortions are evident from the opposite bond angles at the central C‐atom being 116.2 ± 0.5° with the remaining four being 103.7 ± 0.2°.
Thermal Reaction of Azulene‐1‐carbaldehydes with Dimethyl Acetylenedicarboxylate
Authors: Magnussen Anette , Uebelhart Peter , Hansen Hans‐Jürgen 
Published: December 2004

AbstractAzulene‐1‐carbaldehydes which have Me substituents at C(3) and C(8) and no substituent at C(6) react with excess dimethyl acetylenedicarboxylate (ADM) in decalin at 200° to yield exclusively the Diels‐Alder adduct at the seven‐membered ring (cf. Scheme 3). The corresponding 1‐carboxylates behave similarly (Scheme 4). Azulene‐1‐carbaldehydes which possess no Me substituent at C(8) (e.g. 11, 12 in Scheme 2) gave no defined products when heated with ADM in decalin. On the other hand, Me substitutents at C(2) may also assist the thermal addition of ADM at the seven‐membered ring of azulene‐1‐carbaldehydes (Scheme 6). However, in these cases the primary tricyclic adducts react with a second molecule of ADM to yield corresponding tetracyclic compounds. The new tricyclic aldehydes 16 and 17 which were obtained in up to 50% yield (Scheme 3) could quantitatively be decarbonylated with [RhCl(PPh3)3] in toluene at 140° to yield a thermally equilibrated mixture of four tricycles (Scheme 8). It was found that the thermal isomerization of these tricycles occur at temperatures as low as 0° and that at temperatures > 40° the thermal equilibrium between the four tricycles is rapidly established via [1,5]‐C shifts. The establishment of the equilibrium makes the existence of two further tricycles necessary (cf. Scheme 8). However, in the temperature range of up to 85° these two further tricycles could not be detected by 1H‐NMR. When heated in the presence of excess ADM in decalin at 180°, the ‘missing’ tricyclic forms could be evidenced by their tetracyclic trapping products ‘anti’‐45 and ‘anti’‐48, respectively (Scheme 9).
Dicarboxylates of 3‐Methylidene‐β‐lactams: Addition Reactions to the Exocyclic Double Bond, Formation of Spiro‐β‐lactams, and Reductive Ring Opening by Hydrazines
Authors: Gürtler Susanne , Johner Michael , Ruf Sabine , Otto Hans‐Hartwig 
Published: December 2004

AbstractO‐, S‐, and N‐Nucleophiles are added to the exocyclic double bond of the title compounds 1. The addition of O‐ or S‐nucleophiles yields stable products (Scheme 1), while addition of N‐nucleophiles results in thermally labile compounds (Scheme 2). The reaction is studied by spectroscopic methods. From hydrazine adducts, a spiro[azetidine‐3,3′‐pyrazolidine] 7 is obtained, and the addition products of methyl‐ and benzylhydrazine rearrange to pyrazol‐4‐carboxylates 6. Furthermore, the exocyclic double bond is used for the formation of spiro‐β‐lactams either by cyclopropane formation or by Diels‐Alder reactions (Scheme 4). The steric course of all reactions is studied, and it is shown that all reactions with the double bond occur from the side opposite to the bulkier substitutent at C(4) of the β‐lactam ring.
Metal complexes of macrocyclic ligands. Part XXXVII. Synthesis of Heteroditopic Bis‐macrocycles and Their Potential for Preparing Heterobinuclear Metal Complexes
Authors: Urfer André , Kaden Thomas A. 
Published: December 2004

AbstractA new and generally applicable synthetic path for the preparation of heteroditopic bis‐macrocycles using tri‐N‐protected tetraazacycloalkanes as building blocks and bromoacetyl bromide as bridging reagent is described. In the first step, bromoacetyl bromide is used as acylating agent for one of the macrocycles, whereas in the second step it is used as alkylating agent for the second macrocycle, thus giving protected bis‐macrocyclic amides (e.g. 6). After reduction of the amide moiety and deprotection, bis‐azamacrocycles with an ethylene bridge are obtained (e.g. 8). The corresponding homoditopic bis‐macrocycles 16 and 17 are also prepared for comparison purpose. Spectrophotometric studies indicate that bis‐macrocycle 8, which consists of a 12‐ and a 14‐membered ring, binds two metal ions with equal affinity, whereas compound 13, in which an unsubstituted (cyclam) and a trimethyl‐substituted tetraazacyclotetradecane unit (Me3cyclam) are bridged, shows selective metal‐ion binding. The first metal ion is always incorporated into the cyclam unit, whereas the second one binds to the Me3cyclam macrocycle. Thus, by sequential addition of two different metal ions, heterobinuclear complexes can easily be prepared. The electrochemistry of the binuclear Ni2+ complexes, studied by CV and DPV, as well as the EPR spectra of the binuclear Cu2+ complexes clearly indicate metal‐metal interactions.
Thermoconversion of Caryophyllene‐ to Farnesene‐Type Sesquiterpenes. Short access to the enantiomers of (6RS,7RS)‐ and (6RS,7SR)‐6,7‐epoxy‐6,7‐dihydro‐β‐farnesenes
Authors: Giersch Wolfgang K. , Boschung André F. , Snowden Roger L. , Schulte‐Elte Karl H. 
Published: December 2004

AbstractFlash‐vacuum thermolysis of the four diastereoisomeric 5,6‐epoxy‐5,6‐dihydro‐caryophyllenes 1–4 at 500–550°/0.1–0.7 Torr leads to the hitherto unreported enantiomers of (6RS,7RS)‐ and (6RS,7SR)‐6,7‐epoxy‐6,7‐dihydro‐β‐farnesenes ((±)‐5 and (±)‐6, resp.). In particular, (+)‐5 is formed in 45% yield (ca. 90% ee) and is, thus, an attractive chiral building block for natural‐product synthesis.
Antiparallel β‐Sheet Conformation in Cyclopeptides Containing a Pseudo‐amino Acid with a biphenyl moiety
Authors: Brandmeier Volker , Sauer Wolfgang H. B. , Feigel Martin 
Published: December 2004

AbstractThe biphenyl‐containing pseudo‐amino acids 2′‐(aminomethyl)biphenyl‐2‐carboxylic acid (Abc; 1) and 2′‐(aminomethyl)biphenyl‐2‐acetic acid (Aba; 2) are used as rigid spacers in the backbone of the cyclic peptides cyclo (‐Abc‐Ala‐Phe‐Gly‐)2 (5), cyclo(‐Abc‐Ala‐Val‐Gly‐)2 (6), cyclo(‐Aba‐Gly‐Phe‐Ala‐)2 (7), and cyclo(‐Aba‐Ala‐Phe‐Gly‐)2(8). Three different interconverting diastereoisomers are found in solutions of each of these cyclopeptides due to the atropisomerism of the biphenyl units. NMR Techniques and molecular‐dynamics calculations allow to conclude that the major diastereoisomer of 5 (and 6) in (D6)DMSO adopts a β‐sheet conformation. It is proposed that the pseudo‐amino acid 1 of (R)‐chirality forms, with attached L‐amino acids, a H‐bonding pattern comparable to a β‐turn (see D in Fig. 4 and F).
Vitamin‐B12‐katalysierte C,C‐Bindungsverknüpfung: Synthese von Jasmonaten via sequentielle Radikal‐Reaktion
Authors: Busato Stephan , Scheffold Rolf 
Published: December 2004

Vitamin‐B12‐Catalyzed C, C‐Bond Formation: Synthesis of Jasmonates via Sequential Radical ReactionThe Cbl‐catalyzed electroreduction of 3‐(2′‐bromo‐1′‐ethoxyethoxy)cyclopenten (1a) in presence of 1‐cyanovinyl‐acetate (8) gave, in a sequential radical reaction (5‐exo‐trig‐cyclization of 1a followed by addition to 8), 1‐cyano‐2‐(2′‐ethoxy‐hexahydro‐2′H‐cyclopenta[b] furan‐4′‐yl)ethyl acetate (10a). This intermediate was transformed to methyl jasmonate (7; four steps) and epituberolide (9; three steps) in 20 and 31% yield, respectively, from cyclopent‐2‐en‐l‐ol.
The Structure of 1H‐Perimidin‐2(3H)‐one and Its Derivatives in the solid state (x‐ray crystallography and CP/MAS 13C‐NMR), in solution (13C‐NMR), and in the gas phase (mass spectrometry)
Authors: Claramunt Rosa M. , Dotor Julio , Sanz Dionisia , Foces‐Foces Concepción , Llamas‐Saniz Antonio L. , Elguero José , Flammang Robert , Morizur Jean Pierre , Chapon Erik , Tortajada Jeanine 
Published: December 2004

AbstractThe X‐ray crystal and molecular structures of 1‐methyl‐ 1H‐perimidin‐2(3H)‐one (5b) and 1,3‐dimethyl‐1H‐perimidin‐2(3H)‐one (6) were determined. The crystals are built of piles of dimers faced head‐to‐head in 5b and of alternating independent head‐to‐tail molecules in 6, both along the b axis. Semiempirical calculations at the AM 1 level revealed that the eclipsed conformation of the Me groups with respect to the CO group, found in the crystals, is the most stable. The lack of planarity of the whole molecules is a consequence of the packing forces since it is not found in the calculations. A comparative NMR study was carried out in solution (1H and 13C) and in the solid state (CP/MAS 13C) for 1H‐perimidin‐2(3H)‐one (2) and 1H‐benzimidazol‐2(3H)‐one (3) with the conclusion that in both heterocycles the oxo tautomer is the most abundant. The structure in the gas phase was approached by mass spectrometry. In the case of 3, the oxo tautomer loses CO after ionization, while the oxo form of 2 tautomerizes to the hydroxy form which loses, H2O after a [1,3]‐H shift. AM 1 calculations were carried out on the ground and ionized states of 2.
Nucleophilic Substitution in the Allylic System of Codeine and Pseudocodeine: Reactions with lithium cyano(methyl)‐and (aryl)cyanocuprates. Crystal and molecular structure of 8α‐phenyl‐6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan and 6α‐phenyl‐7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan
Authors: Kalinin Valery N. , Belyakova Irina L. , Derunov Vladimir V. , Petrovskii Pavel V. , Yanovski Aleksandr I. , Struchkov Yurii T. , Schmidhammer Helmut , Park Jin K. 
Published: December 2004

AbstractNucleophilic substitution of 6β‐chloro‐7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan (1) and 8α‐bromo‐6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan (2) with lithium cyano(methyl)‐ and (aryl)cyanocuprates(I) (5a–c) was accompanied by allylic rearrangement with both change and retention of orientation of the substituting group (Scheme 1, Table 1). Nucleophilic substitution in 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan‐6α‐yl methanesulfonate (3) and 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methylmorphinan‐6β‐yl methanesulfonate (4) proceeded without allylic rearrangement with both change and retention of the orientation of the substituting group (Scheme 2, Table 1). X‐Ray diffraction studies of the products 6,7‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methyl‐8α‐phenylmorphinan (6b) and 7,8‐didehydro‐4,5α‐epoxy‐3‐methoxy‐17‐methyl‐6β‐phenylmorphinan (7b) were carried out (Figs. 1 and 2).
NMR of Terminal Oxygen. Part 14. Kinetically stabilized simple enols containing methylated uracil groups: Application of a 17O‐NMR test of H‐bonding
Authors: Zhuo Jin‐Cong , Wyler Hugo , Péchy Peter , Dahn Hans 
Published: December 2004

AbstractIn the crystalline N,N′‐dimethylated uracil derivatives 2a, b, the kinetically stabilized enol group forms an H‐bond with OC(4), as demonstrated by increased shielding of specifically labelled 2a and 2b in the 17O‐NMR spectra (Δδ(17O)(C(4)—O)  −30 ppm); absence of dilution and solvent effects show that the H‐bridge is intra‐molecular, forming an eight‐membered chelate ring. The (apparent) shielding effect Δδ(17O) in 2a, b is larger than that in salicylamide. The strong H‐bond explains why the enols 2, in spite of the absence of steric hindrance, are kinetically stabilized.
Organic Diodes Based on Redox‐Polymer Bilayer‐Film‐Modified Electrodes
Authors: Zhao Wenyuan , Marfurt Judith , Walder Lorenz 
Published: December 2004

AbstractThe synthesis of four electropolymerizable 2,2′‐bipyridinium salts with tuned reduction potential (E1∘) is described (N,N′‐ethylene‐4‐methyl‐4′‐vinyl‐2,2′‐bipyridinium dibromide (4; E1∘ –0.48 V), 4‐methyl‐N, N′‐(trimethylene)‐4′‐vinyl‐2,2′‐bipyridinium dibromide (5; E1∘ −0.66 V), N,N′‐ethylene‐4‐methyl‐4′‐[2‐(1H‐pyrrol‐1‐yl)ethyl]‐2, 2′‐bipyridinium bis(hexafluorophosphate) (6b; E1∘ −0.46 V), and 4‐methyl‐4′‐[2‐(1H‐pyrrol‐1‐yl)ethyl]‐N, N′‐(trimethylene)‐2,2′‐bipyridinium bis(hexafluorophosphate) (7b; E1∘ −0.66 V)). E1∘‐Tuning is based on the torsional angle C(3)–C(2)–C(2′)–C(3′), imposed by the N,N′‐ethylene and N,N′‐(trimethylene) bridge. The vinylic compounds 4 and 5 undergo cathodic, the pyrrole derivatives 6b and 7b anodic electropolymerization on glassy carbon electrodes from MeCN solutions, yielding thin, surface‐confined films with surface concentrations of redox‐active material in the range 5 · 10−9 < Γ < 2.10−8 mol/cm2, depending on experimental conditions. The modified electrodes exhibit reversible ‘diquat’ electrochemistry in pure solvent/electrolyte. Copolymerization of 6b or 7b with pyrrole yields most stable electrodes. Bi ayer‐film‐modified electrodes were prepared by sequential electropolymerization of the monomers. The assembly electrode/poly‐6b/poly‐7b behaves as a switch, it transforms – as a Schmitt trigger – an analog input signal (the electrode potential) into a digital output signal (redox state of the outer polymer film). Forward‐(electrode/poly‐7b/poly‐6b) and reverse‐biased assemblies (electrode/poly‐6b/poly‐7b) were coupled to the electrochemical reduction of redox‐active solution species, e.g. N‐ (cyanomethyl)‐N′‐methyl‐4,4′‐bipyridinium bis(hexafluorophosphate) (8). Zener‐diode‐like behavior was observed. Aspects of redox‐polymer multilayer‐film assemblies, sandwiched between two electronic conductors, are discussed in terms of molecular electronic devices.
Synthesis of oligoribonucleotides containing isoguanosine
Authors: Seela Frank , Fröhlich Thomas 
Published: December 2004

AbstractOligoribonucleotides containing isoguanosine (  1,2‐dihydro‐2‐oxoadenosine; isoG;1) were prepared. The building block2was synthesized using the (dimethylamino)methylidene residue as NH2protecting group. The monomethoxytrityl as well as dimethoxytrityl group were introduced at OH–C(5′) (→5and6). Silylation of5with triisopropylsilyl chloride formed the 2′‐O‐blocked derivative7almost exclusively. Reaction with PCl3/1,2,4‐1H‐triazole furnished the phosphonate2which was used in solid‐phase synthesis of the oligoribonucleotides10and11. RNAse T1hydrolyzed U‐A‐G‐U‐U‐isoG‐U‐U‐A‐G (10) at the 3′‐site of G but not of isoG. The self‐complementary oligomer (A‐U‐isoG‐U)3(11) formed a duplex which was less stable than that of (A‐U)6.
New C2‐Chiral Bidentate Ligands Bridging the gap between donor phosphine and acceptor carbonyl ligands
Authors: Peter Kündig E. , Dupré Chantal , Bourdin Bernadette , Cunningham Allan , Pons Dominique 
Published: December 2004

AbstractTwo new C2 chiral bidentate phosphorous ligands have been prepared in enantiomerically pure form. The two phosphorous centers bear electron‐withdrawing groups ((CF3)2CHO, C6F5) and are linked by a trans‐cyclopentane‐1,2‐diol‐derived bridge. Photolysis of [Cr(η6‐C6H6)(CO)3] in the presence of these two new ligands and of two previously reported bidentate phosphites, and fluorophosphinites (L) afforded [Cr(η6‐C6H6)(CO)L] complexes. IR Spectral comparison of the complexes shows the new ligands to be intermediate in their bonding properties between alkyl phosphites and CO.