bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Metal‐Binding Properties of Polybipyridine Ligands Derived from Acyclic and Macrocyclic Polyamines
Authors: Ziessel Raymond , Lehn Jean‐Marie 
Published: December 2004

AbstractSynthetic procedures have been developed for the preparation of ligands bearing two to six pendent, unsubstituted or substituted 2, 2′‐bipyridine groups attached to acyclic (tripode, tetrapode) and macrocyclic (triazanonade‐cane, cyclam, hexacyclen, bis(bipyrido)hexaazamacrocycle) polyamines. Ligands 1‐5 have been obtained in high yield by condensation of 6‐(bromomethyl)‐2, 2′‐bipyridine (9b) with the corresponding amines in the presence of NaOH, H2O, and MeOH. Ligands 6‐8 have been prepared in good yield by condensation of 9b or the di‐ or tetrasubstituted mono (bromomethyl) bipyridine 10b or 11b, respectively, with the corresponding amines in the presence of Na2CO3 and MeCN. Ligand 1 forms hemi‐cage complexes with RuII, FeI, CrII, and CrIII cations and trinuclear complexes with [RuCl2(bpy)2] and [ReCl(CO)5]. Tetrapode 2 and hexapode 4 gave tetranuclear and dinuclear complexes, respectively, by reaction with Fe11 salts. These complexes possess a variety of interesting physical and chemical properties.
Eine weitere, diesmal erfolgreiche Suche nach 3′‐Epilutein in Pflanzen
Authors: Märki‐Fischer Edith , Eugster Conrad Hans 
Published: December 2004

A Further, Now Successful Search for 3′‐Epilutein in PlantsThe 3′‐epilutein, an extremely rare carotenoid, found till now in only one plant, was detected in anthers of flowers of several roses and in those of peonies.
Transport Properties of Anion‐Selective Membranes Based on Cobyrinates and Metalloporphyrin Complexes as Ionophores
Authors: Huser Mario , Morf Werner E. , Fluri Karl , Seiler Kurt , Schulthess Peter , Simon Wilhelm 
Published: December 2004

AbstractZero‐current counter‐transport studies as well as electrodialytic transport experiments on solvent polymeric membranes doped with ionophores for anions have been carried out and were compared with potentiometric measurements on the same membranes. A theoretical description of the observed phenomena corroborates that lipophilic complexes of Co(III) (e. g. aquacyano[heptakis(2‐phenylethyl)]Co(III) cobyrinate perchlorate) and Mn(III) (e. g. lipophilic Mn(III)porphyrin complexes) act as positively charged carriers for anions, whereas a lipophilic Ru(II)porphyrin complex has to be described as an electrically neutral carrier for anions.
2,4‐Disubstituted Pyrrolo[2,3‐d]pyrimidine α‐D‐ and β‐D‐Ribofuranosides Related to 7‐Deazaguanosine
Authors: Seela Frank , Soulimane Tewfik , Mersmann Kann , Jürgens Thomas 
Published: December 2004

AbstractNucleobase‐anion glycosylation (KOH, tris[2‐(2‐methoxyethoxy)ethyl]amine (TDA‐1), MeCN) of the pyrrolo[2,3‐d]pyrimidines 4a–d with 5‐O‐[(1,1‐dimethylethyl)dimethylsilyl]‐2,3‐O‐(1‐methylethylidene)‐α‐D‐ribo‐furanosyl chloride (5) gave the protected β‐D‐nucleosides 6a–d stereoselectively (Scheme 1). Contrary, the β‐D‐halogenose 8 yielded the corresponding α‐D‐nucleosides (9a and 9b) apart from minor amounts of the β‐D‐anomers. The deprotected nucleosides 10a and 11a were converted into 4‐substituted 2‐aminopyrrolo[2,3‐d]‐pyrimidine β‐D‐ribofuranosides 1. 10c, 12, 14, and 16 and into their α‐D‐anomers, respectively (Scheme 2). From the reaction of 4b with 5, the glycosylation product 7 was isolated, containing two nucleobase moieties.
Reaktionen von 5H‐1,2λ5‐Azaphospholen mit Arylazocarbonitrilen sowie Acetylendicarbonsäure‐estern
Authors: Rieda Walter , Fulde Maria , Bats Jan W. 
Published: December 2004

Reactions of 5H,2λ5‐Azaphospholes with Arylazocarbonitriles and Dialkyl AcetylenedicarboxylatesAzaphospholes 1a–c react with activated arylazocarbonitriles to 1,5,2λ5‐diazaphosphorines 2a–c and 3a–c. The reaction of 1a–c with diethyl or dimethyl acetylenedicarboxyiates yields 7H‐1,4λ5‐azaphosphepines 4a–c. The structures of 2b, 3a, and 4a are established by an X‐ray diffraction analysis.
Anion Selectivity of Tetravalent Tin Compounds in Membranes Studied by 119Sn‐, 13C‐ and 1H‐NMR
Authors: Pham Hung‐Viet , Pretsch Ernö , Fluri Karl , Bezegh Andras , Simon Wilhelm 
Published: December 2004

AbstractThe fundamental molecular aspects of trialkyltin compounds of the type R3SnY have been investigated in view of their applicability as ion‐selective components in solvent polymeric membranes. The interaction between these compounds and anions has been studied using 119Sn‐ and 13C‐NMR. Neutral tetracoordinated trialkyltin compounds form a negatively charged pentacoordinated complex upon interaction with Cl‐ions in homogeneous organic phases as well as in membranes in contact with aqueous solutions. Although in a homogeneous phase, the electronegative substituent Y determines the complex‐formation constant, it has no influence on the potentiometric anion selectivity in liquid membranes containing trialkyltin carriers R3SnY with different Y. The observed selectivity pattern is not given by the magnitude of the stability constants in a homogeneous phase but is dictated by the prevailing association‐dissociation process leading to tetracoordinated compounds which change in constitution due to varying sample composition, The results obtained from equilibrium studies of tetravalent mono tin compounds with anions in both homogeneous phase and in two‐phase systems confirm the earlier hypothesis that trialkyltin compounds incorporated in solvent polymeric membranes act as electrically neutral carriers for anions.
Neue Synthese von (−)‐(R)‐Cembren A, Synthese von (+)‐(R)‐Cembrenen und (+)‐(S)‐Cembren
Authors: Farkas Imre , Pfander Hanspeter 
Published: December 2004

Novel Synthesis of (−)‐(R)‐Cembrene A, Synthesis of (+)‐(R)‐Cembrenene and (+)‐(S)‐CembreneA novel synthesis of (−)‐(R)‐cembrene A ((−)‐3) was developed using the Sharpless epoxidation for the introduction of the chiral center. Furthermore, the synthesis of (+)‐(R)‐cembrenene ((+)‐4) showed that this cembranoid must have the (R)‐configuration and not, as previously reported, the (S)‐configuration. Selective hydrogenation of (+)‐4 afforded (+)‐(S)‐cenibrene ((+)‐5).
1‐(2′‐Deoxy‐β‐D‐xylofuranosyl)thymine Building Blocks for Solid‐Phase Synthesis and Properties of Oligo(2′‐Deoxyxylonucleotides)
Authors: Rosemeyer Helmut , Seela Frank 
Published: December 2004

Abstract1‐(2′‐Deoxy‐β‐D‐threo‐pentofuranosyl)thymine (= 1‐(2′‐deoxy‐β‐D‐xylofuranosyl)thymine; xTd; 2) was converted into its phosphonate 3b as well as its 2‐cyanoethyl phosphoramidite 3c. Both compounds were used for solid‐phase synthesis of d[(xT)12‐T] (5), representing the first DNA fragment build up from 3′–5′‐linked 2′‐deoxy‐‐β‐D‐xylonucleosides. Moreover, xTd was introduced into the innermost part of the self‐complementary dodecamer d(G‐T‐A‐G‐A‐A‐xT‐xT‐C‐T‐A‐C)2 (9). The CD spectrum of d[(xT)12–T] (5) exhibits reversed Cotton effects compared to d(T12) (6; see Fig. 1), implying a left‐handed single strand. With d(A12) (7) it could be hybridized to form a propably Left‐handed double strand d(A12) · d[(xT)12–T] (7·5) which was confirmed by melting experiments in combination with temperature‐dependent CD spectroscopy. While 5 was hydrolyzed by snake‐venom phosphodiesterase, it was resistant towards calf‐spleen phosphodiesterase. The modified, self‐complementary duplex 9 was hydrolyzed completely by snake‐venom phosphodiesterase, at a twelvefold slower rate compared to unmodified 8; calf‐spleen phosphodiesterase hydrolyzed 9 only partially.
Versatile Stereoselective Synthesis of Completely Protected Trifunctional α‐Methylated α‐Amino Acids Starting from Alanine
Authors: Altmann Eva , Nebel Kurt , Mutter Manfred 
Published: December 2004

AbstractA new route to completely protected α‐methylated α‐amino acids starting from alanine is described (see Scheme). These derivatives, which are obtained via base‐catalyzed opening of the oxazolidinones (2S,4R)‐ and (2R,4S)‐2, can be directly employed in peptide synthesis. The synthesis of both enantiomers of Z‐protected α‐methylaspartic acid β‐(tert‐butyl)ester (O4‐(tert‐butyl) hydrogen 2‐methylaspartates (R) or (S)‐4a), α‐methyl‐glutamic acid γ‐(tert‐butyl) ester (O5‐(tert‐butyl) hydrogen 2‐methylglutamate (R)‐ or (S)‐4b), and of Nε‐bis‐Boc‐protected α‐methyllysine (N6,N6‐bis[(tert‐butyloxy)carbonyl]‐2‐methyllysine (R)‐ or (S)‐4c) is described in full detail.
Synthesis of 1H,2,3‐Triazoles from 2‐Substituted Cyclododecanones and Phenyl Azide
Authors: Ognyanov Vassil I. , Hesse Manfred 
Published: December 2004

AbstractBy reaction with phenyl azide, 2‐cyano‐ and 2‐(ethoxycarbonyl)‐substituted cyclododecanones are converted into 5‐amino‐ and 5‐hydroxy‐1H‐1,2,3‐triazoles, respectively. The possible reaction mechanism is discussed.
Regioselektive 1,3‐dipolare Cycloadditionen von Thiocarbonyl‐yliden mit 1,3‐Thiazol‐5(4H)‐thionen
Authors: Mlostoń Grzegorz , Linden Anthony , Heimgartner Heinz 
Published: December 2004

Regioselective 1,3‐Dipolar Cycloadditions of Thiocarbonyl Ylides with 1,3‐Thiazole‐5(4H)‐thionesThe thiocarbonyl ylides 13 and 1,3‐thiazol‐5(4H)‐thiones 1 undergo a smooth reaction to yield spirocyclic 1,3‐dithiolanes 14–16 (Schemes 4–6). The 1,3‐dipolar cycloadditions occur in a regioselective manner, but the orientation of the thiobcnzophenone‐S‐methylide (13b) differs from that of the cycloalkane thione‐S‐methylides 13a and 13c. Whereas the 1,3‐cycloadduct with 13b is formed in accordance with frontier‐orbital considerations, the inverse orientation in the reactions with 13a and 13c most likely is the result of steric hindrance in the transition state. The thiocarbonyl ylides have been prepared in situ from the corresponding 2,5‐dihydro‐1,3,4‐thiadiazoles 12. The more stable aliphatic precursors 12a and 12c undergo decomposition at 50°, the unstable 12b at −30°.
Asymmetric Catalysis by Vitamin B12. The Mechanism of the Cob(I)alamin‐Catalyzed Isomerization of 1,2‐Epoxycyclopentane to (R)‐Cyclopent‐2‐enol
Authors: Bonhôte Pierre , Scheffold Rolf 
Published: December 2004

AbstractThe isomerization of 1,2‐epcxycyclopentane (1) to enantiomerically enriched (R)‐cyclopent‐2‐enol (2) in protic solvents is catalyzed by cob(I)alamin. The enantiomeric excess (e.e.) of (R)‐2 is usually ca. 60%; it is only slightly dependent on the temperature, but increases with decreasing dielectric constant ε of the solvent. Standard kinetic methods show the reaction to be first order in vitamin B12 and zero order in 1. The rate constant increases exponentially with increasing ε of the solvent. An Arrhenius plot at ε = 40 gives activation parameters ΔH≠ = 78 ± 4 kJ·mol−1 and ΔS≠ = −49 ± 1 J·mol−1·K−1. The isomerization 1 → 2 proceeds in two steps (Schemes 2 and 7): (i) The epoxide ring is first opened by the proton‐assisted fast and irreversible nucleophilic attack of the chiral CoI catalyst to form diastereoisomeric (1R,2R)‐ and (1S,2S)‐(2‐hydroxycyclo‐pentyl)cob(III)alamins 6 in a ratio of ca. 4:1 which are the dominant species in the steady state; (ii) The intermediates 6 then decompose in the rate‐limiting step to form 2 and recycled catalyst. Experiments with specifically 2H‐labeled 1 showed the hydro‐cobalt elimination 6 → 2 to be non‐stereoselective. It proceeds via reversible CoC bond homolysis to a free 2‐hydroxycyclopentyl radical from which stereoelectronically controlled H‐abstraction by Co11 takes place.
C‐Glykoside der N‐Acetylneuraminsäure. Synthese und Untersuchung ihrer Wirkung auf die Vibrio cholerae Sialidase
Authors: Wallimann Kurt , Vasella Andrea 
Published: December 2004

C‐Glycosides of N‐Acetylneuraminic AcidThe synthesis of the C‐glycosides 8, 15, and 9 of N‐acetylneuraminic acid is described. Hydroxymethylation of the Li‐ester enolate, derived from 5, yielded the protected C‐glycosides 7 and 10 (46%; 3:1), which were deprotected to yield 8 (54%) and 15 (51%; Scheme 2). The mesylate 16 was obtained from 7 (73%) and transformed via the azide 17 (75%) into the acid 18 (66%) and the amino acid 9 (Scheme 3). The configuration at C(2) of 17 was proved by transforming 17 into the bicyclic lactam 19. Both 8 and 15 are very weak inhibitors of Vibrio cholerae sialidase; 9 appears to stimulate this enzyme.
Trialkyltin Compounds as Neutral Carriers for Anions in PVC Liquid Membranes and Complex Formation with Oxoanions
Authors: Fluri Karl , Koudelka Juraj , Simon Wilhelm 
Published: December 2004

AbstractUnder the influence of an electric field, trialkyltin compounds of the type R3SnX behave as electrically neutral carriers for anions in poly(vinyl chloride) liquid membranes. The interaction of tinorganic compounds with oxoanions was studied in organic phase by means of119Sn‐NMR‐monitored titrations. In the case of tributyltin chloride, no appreciable amount of complex was formed with hydrogensulfate, whereas dihydrogenphosphate gave rise to a new species. Dioctyltin dichloride and dioctyltin dioctyltin diacetate formed a 1:2 (salt/ligand) complex with hydrogenphosphate.
Efficient Synthesis of Enantiomerically Pure α‐Ionone from (R)‐ and (S)‐α‐Damascone
Authors: Fehr Charles , Guntern Olivier 
Published: December 2004

Abstract(R)‐ and (S)‐α‐ionone ((R)‐ and (S)‐1, resp.) were prepared from (R)‐ and (S)‐α‐damascone ((R)‐ and (S)‐3, resp.) without racemization in 48% yield employing a new enone transposition. The described transposition is complementary to existing methods whose application is often prohibited by the structural requirements of the substrate. The now easily accessible α‐ionones of desired absolute configuration are useful as chiral building blocks for terpenoid synthesis.
1,7‐Dideaza‐2′‐deoxyadenosine: Building blocks for solid‐phase synthesis and secondary structure of base‐modified oligodeoxyribonucleotides
Authors: Seela Frank , Wenzel Thomas 
Published: December 2004

AbstractThe 1,7‐dideaza‐2′‐deoxyadenosine (c1c7Ad; 1) was converted into building blocks 3a,b for solid‐phase oligodeoxyribonucleotide synthesis. Testing various N‐protecting groups – benzoyl, phenoxyacetyl, [(fluoren‐9‐yl)methoxy]carbonyl, and (dimethylamino)methylidene – only the latter two were found to be suitable (1 → 4b, d). Ensuing 4,4′‐dimethoxytritylation of 4d and phosphitylation afforded the 3′‐phosphonate 3a or the 3′‐[(2‐cyanoethyl)diisopropylphosphoramidite] 3b. Self‐complementary oligonucleotides with alternating dA or c1c7Ad and dT residues (7 and 8) as well as palindromic oligomers such as d(C‐G‐C‐G‐c1c7 A‐c1c7 A‐T‐T‐C‐G‐C‐G) (10) and d(G‐T‐A‐G‐c1c7 A‐c1c7 A‐T‐T‐C‐T‐A‐C) (12) were synthesized. Duplex stability was decreased because 1 cannot form Watson‐Crick or Hoogsteen base pairs if incorporated into oligonucleotides. On the other hand, the structural modifications in 10 and 12 forced these palindromic oligomers to form hairpin structures.
Base Hydrolysis of Pentaaminecobalt(III) Complexes: The [CoX(dien) (dapo)]n+ system. Part 1. Syntheses, structures, configuration, and spectroscopy
Authors: Comba Peter , House Donald A. , Jackson W. Gregory , Marty Werner , Stoeckli‐Evans Helen , Zipper Luc 
Published: December 2004

AbstractOxygentation of aqueous solutions of CoIII in presence of stoichiometric amounts of N‐(2‐aminoethyl)ethane‐1,2‐diamine (dien) and 1,3‐diaminopropan‐2‐ol (dapo) produces μ‐peroxocobalt(III) dimers. Acid cleavage (HCI) yields mer‐exo(H)‐, mer‐endo (H)‐, unsym‐fac‐exo(OH)‐, and unsym‐fac‐endo(OH)‐[CoCl(dien)(dapo)]2+ (A–D)(X = Cl), resp. and unsym‐fac‐[Co‐(dien)(dapo‐N,N′,O)]3+ (G). Isomer seperation was achieved by fractional crystallization as ZnCl and ClO salts and by ion‐exchange chromatography. The corresponding bromo, azido, nitrito‐O, nitro‐N, thiocyanato, hydroxo, and aqua complexes were also synthesized. Optically resolved samples were prepared for chiral compounds, and the complexes were structurally characterized by X‐ray analyses (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Lambda} \limits^ \to $\end{document}(−)436(CD)‐A (X = N3)), (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Delta} \limits^ \to $\end{document}(−)436(CD)‐B). (X = N3), \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Delta} \limits^ \to $\end{document} (+)436(CD)‐B by their chiroptical properties, and by 13C‐NMR spectroscopy supported by 1H‐NMR, IR, CD, and UV/VIS spectroscopy. \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Lambda} \limits^ \to $\end{document}(−)436(CD)‐mer‐exo(H)‐[Co(N3)(dien)(dapo)](hydrogen di‐O‐benzoyl‐L‐tartrate)2.4 H2O crystallizes in the orthorhombic space group P212121, a = 7.676(1) Å, b = 19.457(1) Å, c = 34.702(2) Å. \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Lambda} \limits^ \to $\end{document}(−)436(CD)‐mer‐endo(H)‐[Co(N3)(dien)(dapo)] (hydrogen di‐O‐benzoyl‐L‐tartrate)2.2.75 H2O crystallizes in the triclinic space group P1, a = 8.062(3) Å b = 10.296(1) Å, c = 15.056(2) Å, alpha = 80.55(1)°, β = 85.18(2)°, γ = 89.10(2)°. \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\it \Delta} \limits^ \to $\end{document}(+)436(CD)‐mer‐endo(H)‐[Co(N3)(dien)(dapo)](hydrogen di‐O‐benzoyl‐L‐tartrate)2. 5.75 H2O crystallizes in the triclinic space group P1, a = 7.742(1) Å, b = 10.014(1) Å, c = 18.045(2) Å, α = 99.57(1)°, β = 92.87(1)°, γ = 102.56(1)°. The absolute configurations of the three cations were determined unambiguously. Interconversions of the various isomers and derivatives and structural, configurational, and spectroscopic aspects are discussed in detail.
Benzene Oxidation by ‘Bare’ FeO+ in the Gas Phase
Authors: Schröder Detlef , Schwarz Helmut 
Published: December 2004

AbstractBare FeO+ reacts in the gas phase with benzene at collision rate (k = 1.3 × 10−9 cm3 molecule−1 s−1), giving rise to the formation of Fe(C6H4)+/H2O(5%), Fe(C5H6)+/CO(37%), Fe(C5H5)+/CO/H. (2%), and Fe+/C6H5OH (56%). Neither the reaction rate nor the product distribution are subject to a significant kinetic isotope effect, thus, ruling out several mechanistic variants described in the literature to the operative for ‘analogous’ arene oxidation processes in solution. A mechanism is suggested which is in keeping with the experimental findings, and which also accounts for some remarkable results obtained, when two [Fe, C6,H6H6O]+ isomers are generated and subjected to a neutralization‐re‐ionization experiment in the gas phase.
Stereoselectivity in Reactions of Metal Complexes. Part XV. Structure and stability of chiral cobalt(III) complexes with pentadentate ligands
Authors: Bernauer Klaus , Stoeckli‐Evans Helen , Hugi‐Cleary Deirdre , Hilgers Hermann J. , Abd‐el‐Khalek Habib , Porret Joëlle , Sauvain Jean‐Jacques 
Published: December 2004

AbstractThe syntheses and characterization of four new linear pentadentate ligands and their CoIII complexes are described: N,N′‐[(pyridine‐2,6‐diy)bis(methylene)]bis[sarcosine] (sarmp), N,N′‐[(pyridine‐2,6‐diyl)bis(methylene)]bis[(R)‐ or (S)‐proline] ((R,R)‐ or (S,S)‐promp), N,N′‐[(pyridine‐2,6‐diyl)bis(methylene)]bis[N‐(methyl)‐(R)‐ or (S)‐alanine] ((R,R)‐ or (S,S)‐malmp); 2,2′‐[pyridine‐2,6‐diyl]bis[(S)‐ or rac‐N‐(acetic acid)pyrrolidine] ((S,S)‐ or rac‐bapap). The complexes were characterized and, with but one exception, complex formation is stereospecific: Δ‐exo‐(R,R) (or Λ‐exo‐(S,S)) for promp and Λ‐(R,R) (or Δ‐(S,S)) for bapap. The exception is [Co((R,R)‐ or (S,S)‐malmp)H2O]ClO4 for which two forms are obtained, to which Λ‐endo‐(R,R) (or Δ‐endo‐(S,S)) and, tentatively, Δ‐unsymmetric‐(R,R)‐ (or Λ‐unsymmetric‐(S,S)‐) configurations are assigned. X‐Ray crystal structures are presented for the complexes [Co(sarmp)H2O]ClO4, [Co((S,S)‐promp)H2O]ClO4, [Co(rac‐bapap)H2O]ClO4 and endo‐[Co(rac‐malmp)H2O]ClO4. Ligand acid dissociation and CoII and FeII complex‐formation constants are reported.
Nucleotides. Part XXXIX Synthesis of arabinonucleoside phosphoramidite building blocks
Authors: Resmini Matthias , Pfleiderer Wolfgang 
Published: December 2004

AbstractHigh‐yield chemical syntheses of phosphoramidite building blocks of the four arabinonucleosides aUrd (1), aCyd (2), aAdo (3), and aGuo (4), suitable for (3′–5′)oligoarabinonucleotide synthesis are described. The problem of 2′‐hydroxy group protection was solved by introduction of the versatile 2‐(4‐nitrophenyl)ethoxycarbonyl (npeoc) residue, which was also used for aglycon protection.
Carbocyclic Analogs of Nucleosides. Part 3. Synthesis of a new sulfone analog of cyclic adenosine 3′,5′‐monophosphate
Authors: Jenny Thomas F. 
Published: December 2004

AbstractThe novel uncharged analog 2 of adenosine 3′,5′ ‐monophosphate (1) was prepared in its racemic form. To increase membrane permeability, the phosphate diester monoanion group of 1 was replaced by a dimethylene sulfone unit ( = methanosulfonylmethano group), and the 2′‐OH group was removed. To decrease lability against acid‐catalyzed depurination, the ring O‐atom was replaced by a CH2 group. All three modifications are also expected to increase the stability of analog 2 towards enzymatic degradation. The carbocyclic skeleton of 2 was constructed from trinorbornenecarbaldehyde 3 (see Scheme 1–3), and the adenine precursor 6‐chloropurine was introduced in the carbocyclic unit via an SN2 reaction based on Mitsunobu chemistry (Schemes 4 and 5).
Synthese chiraler Kobalt‐Komplexe mit planoid‐tetradentatem Ligand‐System
Authors: Härter Ralph , Wegmuth Christophe , Scheffold Rolf , Engel Peter , Linden Anthony 
Published: December 2004

Synthesis of Chiral Cobalt Complexes with Planoid‐Tetradentate Ligand SystemThe synthesis of a series of Cbl‐related, achiral CoIII complexes 9a–c as well as enantiomerically pure, C2‐symmetric CoIII complexes 15 and 18, is reported (Schemes 3, 5, and 7). The crystal structures of 9c and 15 were determined. Complex 18 acts as an enantioselective catalyst in the isomerization of 1,4‐epiperoxides to hydroxycycloalkenones.
Synthesis and Electronic Properties of Intensely Coloured Iron(II) complexes with new 4‐substituted planar tridentate nitrogen ligands analogous to 2, 2′: 6′, 2″‐terpyridine
Authors: Bochet Christian G. , Piguet Claude , Williams Alan F. 
Published: December 2004

AbstractThe para‐substituted tridentate ligands 2,6‐bis[1‐(3,5‐dimethoxybenzyl)benzimidazol‐2‐yl]‐4′‐X‐phenyl)‐pyridine (X = H: L3; X = NO2: L4; X = NEt2: L5) have been synthesized in six steps using Kröhnke reactions. Spectroscopic results show that the electronic properties of the ligands are strongly influenced by the nature of the substituent bound to the pyridine ring and extended Hückel calculations performed on 4‐(X‐phenyl)pyridine fragments give a qualitative insight into the factors responsible for the striking differences observed in the absorption spectra. Upon complexation to FeII, the ligands L2–L5 give intensely coloured pseudo‐ocatahedral low spin [Fe(Ln)2]2+ (n = 2–5) complexes in acetonitrile solution. Electrochemical and spectroscopic measurements show that the particular electronic characteristics associated with each substituent strongly influence the properties of the resulting FeII complexes as demonstrated by the very intense MLCT transition (ϵ > 50000 M−1 cm−1) observed in the green complex [Fe(L5)2]2+.
Synthesis of Thiazole and Fused Thiazolo Derivatives
Authors: Urleb Uroš , Neidlein Richard , Kramer Walter 
Published: December 2004

AbstractThe syntheses of thiazole and fused thiazolo derivatives 2–4, 6–8, 10a–11b, 13–16 from heterocylic isothiocyanates 1, 5, 9, and 12 bearing an ortho ester group and bifunctional reagents, such as substituted propargylamines, is described. Different regioselectivity of intramolecular nucleophilic attack of the thiourea S‐atom on the C  C bond, resulting in the formation of both thiazolo and thiazino derivatives, as well as NMR structure elucidation are discussed.