bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conformational Flexibility of the Methoxyphenyl Group Studied by Statistical Analysis of Crystal Structure Data
Authors: Hummel Wolfgang , Huml Karel , Bürgi Hans‐Beat 
Published: December 2004

AbstractIn a large sample of observed methoxyphenyl groups, the twist angle τ about the MeO‐CPh bond measuring internal rotation of the MeO group shows a continuous distribution with maxima at (0°) (coplanar conformation) and (∼90°) (perpendicular conformation). The preferred conformation of methoxyphenyl depends on the nature of the ortho‐‐substituents: In general, it is coplanar in the case of one or two ortho‐hydrogens, and perpendicular in the case of two substituents. The internal rotation of the MeO group is accompained by systematic variations in bond angles and bond distances: 1 if MeO is twisted out of plane, the bond angle CH3OCPh decreases from 117.7°, until it reaches a minimum of 114.9° at τ = ±90°. The OCC angle which is syn to CH3 for τ = 0° decreases from 124.6° to a minimum of 115.4° at τ = ±180°. These angles changes keep the nonbonded distance CH3 …︁ ortho substituent maximal during internal rotation of MeO and tend to minimize the corresponding strain energy. (2) In the perpendicular conformation, the O‐atom is ∼ 0. 06 Å displaced from the Ph plane, O and CH3 and being on opposite sides of this plane. In addition, small but systematic increases of bond lengths MeOCPh and CH3O are observed. These variations indicate a decrease in conjugation with increasing twist angle. Their interdependence during twisting and the magnitudes of the changes are close values obtained by ab initio calculations.
The Reaction of Water with Iron‐ and Rutheniuncarbonyl Complexes of Polyolefins: 1,2‐ and 1,4‐hydrogenation of 1,3‐dienes. hydrogenolysis of allylic ethereal bonds and deoxygenation of 7‐oxabicyclo[2.2.1]hept‐2‐enes
Authors: Araki Shuki , Bonfantini Edia , Vogel Pierre 
Published: December 2004

AbstractUnder basic conditions, H2O reacts with tricarbonyl[(1R,2R,3S,4S,5R,6S)‐C,5,6,C‐η‐(2‐exo,3‐exo‐bis‐(chloromethyl)‐5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]heptane)]iron) (1), and ‐ruthenium (4), with tricarbonyl‐[(1R,2R,3S,4S)‐C,2,3,C‐η‐(2,3,5,6‐teramethylidene)‐7‐oxabicyclo[2.2.1]heptane)]iron (6) and ‐ruthenium (7), and with cis‐η‐[1S,2S,3R,4S,5S,6R)‐C,2,3,C‐η : C‐η‐(2,3,5,6‐tetramethylidene‐7‐oxabicyclo)[2.2.1]heptane)bis‐(tricarbonyliron) (11)] to give products of demetallation and 1,2‐ or/and 1,4‐hydrogenation. Reductive demetallation of tricarbonyl[C,5,6,C‐η‐(1‐(dimethoxymethyl)‐5,6‐dimethylidenecylohexa‐1,3‐diene]iron (14) required heating under acidic conditions, giving 2,3‐dimethylbenzaldehyde (16). H2O reacted under neutral conditions with cis‐heptacarbonyl‐μ‐[(1RS,2SR,3RS,4SR,5RS,6SR)‐2,3‐η : C,5,6,C‐η‐(1‐(dimethyoxymethyl)‐5,6,‐(dimethylidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene]diiron (17) and with tricaboyl[(1RS,2SR,3RS,4SR,5RS,6SR)‐C‐η5,6,C‐η‐(1‐(dimethyoxymethyl)‐5,6‐dimethyldidene‐7‐oxabicyclo[2.2.1]hept‐2‐ene)]iron (18) to give the orthoquinodimethane complex 14 as major product. This reaction was accompanied by hydrogenolysis of the allylic ethereal C(4)O(7) bond in 17 and 18 and gave tricarbonyl[(1RS,5RS,6SR)‐C,5,6,C‐η‐(1‐(dimethoxymethyl)‐5,6‐dimethylidenecylohex‐2‐en‐1‐ol)]iron (21) as minor product. The latter was not an intermediated of reaction 17 → 14. Reactions with D2O allowed one to discuss the possible mechanism of this deoxygenation process. With Trans‐heptacarbonyl‐μ‐[(1RS,2SR,3RS,4SR,5RS,6SR)‐2,3‐η : C,5,6,C‐η‐(1‐(dimethoxymethyl‐5,6‐dimethylidene‐7‐oxabicyclo[2.2.1]‐hept‐2‐ene)diiron (38)], the reaction with THF/H2O gave 14 nearly quantitatively, with no D‐incorporation in the presence of D2O.
Pteridines. Part LXXXVII. Synthesis and Properties of 8‐Substituted 2‐Thiolumazines
Authors: Hübsch Walter , Pfleiderer Wolfgang 
Published: December 2004

AbstractVarious 8‐substituted 2,8‐dihydro‐2‐thioxopteridin‐4(3H)‐ones (14–21) and 2‐(methylthio)pteridin‐4(8H)‐ones (27–32) have been synthesized by condensation of the appropriate 5‐amino‐6‐(substituted amino)‐1,2‐dihydro‐2‐thioxopyrimidin‐4(3H)‐ones (22–34) and 5‐amino‐6‐(substituted amino)‐2‐(methylthio)pyrimidin‐4(3H)‐ones (25, 26), respectively, with glyoxal, biacetyl, and benzil. The presence of a quinonoid cross‐conjugated π‐electron system makes this type of compounds susceptible to nucleophilic additions in position 7, which leads to intramolecular (43, 45) and intermolecular (44) covalent adducts. The newly synthesized compounds have been characterized by elemental analyses, pKa determinations, 1H‐NMR and UV spectra. UV‐Spectral changes in dependence of the pH are associated with the most appropriate molecular species including the monocations, neutral forms, covalent adducts, mono‐ and dianions.
Transition‐Metal Complexes with Bidentate Ligands Spanning trans‐Positions. Part XVII. Some platinum(II) complexes with anionic ligands such as methoxide, formate, carboxylate, hydride, and borohydride, and the X‐ray crystal structure of [PtHCl()] (PP = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene)
Authors: Bracher Gustav , Kellenberger Bruno , Venanzi Luigi M. , Bachechi Fiorella , Zambonelli Luigi 
Published: December 2004

AbstractThe complexes trans‐[PtXY(2] (X = H or Me; Y = OMe, OCHO, CO2H, and BH4; 2 = 2,11‐bis{bis[3‐(trifluoromethyl)phenyl]phosphinomethyl}benzo[c]phenanthrene) were prepared, and their decompositions to trans[PtHX(2)] were studied. Some binuclear hydrido‐bridged complexes, e.g.[(2)HPt(μ‐H)PtH(2)]+, were also obtained. The preparation of complexes trans‐[PtHX(28)2] (X = H or Me, 28 = bis[3‐(trifluoromethyl)phenyl]benzylphosphine) is also reported. The X‐ray crystal structure of trans‐[PtHCl1)] (1 = 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene) was carried out.
Applications of ENDOR spectroscopy to radical cations in freon matrices. Part 2. The radical cation of 2,3‐diazabicyclo[2.2.2]oct‐2‐ene
Authors: Gerson Fabian , Qin Xue‐Zhi 
Published: December 2004

AbstractThe radical cation of 2,3‐diazabicyclo[2.2.2]oct‐2‐ene (1), generated by γ‐rays in a CF2ClCFCl2 matrix, has been fully characterized by its hyperfine data with the use of ESR, ENDOR, and TRIPLE resonance spectroscopy. The isotropic coupling constants for \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }}$\end{document} are +3.14 mT for the two 14N Nuclei in the azo group, −0.336 mT for the two protons at the bridgehead C atoms, and +151 and +0.135 mT for the sets of four exo‐ and four endo‐protons, respectively. MO calculations indicate that these values are consistent with an electron removal from an orbital represented by the antibonding combination (n_) of the lone‐pair atomic orbitals at the two N atoms. The corresponding radical anion \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }}$\end{document} is persistent in fluid solution and its hyperfine data, combined with MO calculations, point to an electron uptake into the antibonding π orbital (π*) of the azo group. It is, thus, reasonable to classify \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{+}\kern-4pt {.} }}$\end{document} as a σ and \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\scriptstyle {{\relbar}\kern-4pt {.} }}$\end{document} as a π radical.
β‐Cleavage of Bis(homoallylic) Potassium Alkoxides. Synthesis of γ‐damascone
Authors: Snowden Roger L. , Linder Simon M. 
Published: December 2004

AbstractStarting from the γ‐lactone cis‐1, two new syntheses of γ‐damascone ((E)‐4) are described. In both syntheses, the key step involves the β‐cleavage of a bis(homoallylic) potassium alkoxide, viz. the transformation of 3a to 20 and (E/Z)‐4, and the conversion of 21a to 23 and (E/Z)‐24.
Diastereoselektive Alkylierung von 3‐Aminobutansäure in der 2‐Stellung
Authors: Estermann Heinrich , Seebach Dieter 
Published: December 2004

Diastereoselective Alkylation 3‐Aminobutanoic Acid in the 2‐PositionThe enantiomerically pure 3‐aminobutanoic acids (R)‐ and (S)‐6 are readily available by preparative HPLC separation of the two diastereoisomers 5 obtained from addition of (S)‐phenethylamine to methyl crotonate and subsequent hydrogenolysis (Scheme 2). (S)‐Methyl 3‐(benzoylamino) butanoate ((S)‐3) is also available by enzymatic kinetic resolution with pig‐liver esterase. The N‐benzyl‐ and N‐ benzyloxycarbonyl derivatives rac3,8, and 9 of 3‐aminobutanoates are doubly deprotonated with LDA and alkylated or aminated in high selectivity (17 examples, relative topicity like; see Tables 1 and 2). The configuration of three of the products is assigned (Schemes 4–6), and in four cases, the free α‐substituted β‐amino acid is prepared by acidic hydrolysis (see Table 3). It is shown that the doubly lithiated β‐amino‐acid derivative is solubilized, and its reactivity may be strongly influenced by the presence of 3 equiv. of LiCl.
Synthesis of New, Unnatural Macrocyclic Trichothecenes: 3‐isoverrucarin A ((1″‐O)(3→4)abeo‐verrucarin A), verrucinol, and verrucene. 46th Communication on verrucarins and roridins
Authors: Jeker Nicolas , Tamm Christoph 
Published: December 2004

AbstractA new unnatural macrocyclic trichothecene, an analogue of verrucarine A (1), which was named 3‐Isoverrucarin A ((1″‐O)(3→4)abeo‐verrucarin A; 3) was synthesized starting from anguidine (5). The two key reactions were the removal of the 4β‐acetoxy group of anguidine (5) by a Barton deoxygenation and the final macrolactonization. During the cyclization procedure, two unexpected new macrocyclic by‐products, which were named verrucinol (19) and verrucene (20), were formed. They represent novel types of macrocyclic trichothecenes, the macrolidic moiety of verrucene (20) consisting only of the (Z,E)‐muconic‐acid residue. The formation of the analogous macrolide 26 of verrucene (20) was not possible, probably because the ring strain is too strong.
Synthese von Triafulven‐Vorstufen aus trisubstituierten Cyclopropanen
Authors: Weber Andreas , Sabbioni Gabriele , Galli Roberto , Stämpfli Urs , Neuenschwander Markus 
Published: December 2004

Synthesis of Triafulvene‐Precursors from Trisubstituted CyclopropanesTrisubstituted cyclopropanes 5a–f are prepared by carbene addition to the appropriate olefins. While 5a (Y = OAc) and 5c (Y = Cl) rearrange in the presence of BuLi, 5d (Y = SPh) is stable enough to allow the envisaged sequence for triafulvene (Scheme 2) : halogen‐Li exchange, followed by methylation of 6d, gives 7d in a 93% yield; after base‐induced elimination of HBr from 7d, the key precursor 1‐methylene‐2‐(phenylthio)cyclopropane (9, 70% yield) is isolated. Compound 9 is transformed into the corresponding sulfoxide 10 (83%), sulfone 11 (80%), and sulfonium fluoroborate 12 (95% yield) by subsequent oxidation and methylation, respectively. Some 1H‐NMR results of cyclopropanes 5a–f and 7d as well as of methylidene‐cyclopropanes 9–11 are discussed.
Mechanistic and Synthetic Studies on the Formation of 1,2,4‐Trioxanes Related to Arteannuin. Photooxygenation of a bicyclic dihydropyran
Authors: Jefford Charles W. , Wang Ying , Bernardinelli Gérald 
Published: December 2004

AbstractThe photooxygenation of (4R,4aS,7R)‐4,4a,5,6,7,8‐hexahydro‐4,7‐dimethyl‐3H‐2‐benzopyran (16) was performed in (i) MeOH, (ii) acetaldehyde, and (iii) acetone at −78°. The products obtained respectively were (i) (2R)‐2‐[(1S,4R)‐4‐methyl‐2‐oxocyclohexyl]propyl formate (17; 72% yield), (ii) 17 (54.5%), (1R,4R,4aS,7R)‐3,4,4a,5,6,7‐hexahydro‐4,7‐dimethyl‐1H‐2‐benzopyran‐2‐yl hydroperoxide (19; 16.7%), a 12:1 ratio of (3R,4aR,7R,7aS,10R,11aR)‐7,7a,8,9,10,11‐hexahydro‐3,7,10‐trimethyl‐6H‐[2]benzopyrano[1,8a‐e]‐1,2,4‐trioxane (20) and its C(3)‐epimer 21 (17%), together with evidence for the 1,2‐dioxetane (22) originating from the addition of dioxygen to the re‐re face of the double bond of 16, and iii) unidentified products and traces of 22. Addition of trimethylsilyl trifluoromethanesulfonate (Me3SiOTf) to the acetone solution of 16 after photooxygenation afforded (4aR,7R,7aS,10R,11aR)‐7,7a,8,9,10,11‐hexahydro‐3,3,7,10‐tetramethyl‐6H‐[2]benzopyrano[1,8a‐e]‐1,2,4,‐trioxane (23, 40%). The photooxygenation of 16 in CH2Cl2 at −78° followed by addition of acetone and Me3SiOTf afforded 17 (11%), 23 (59%), and (4aR,7R,7aS,10R,11aR)‐7,7a,8,9,10,11‐hexahydro‐3,3,7,10‐tetramethyl‐6H‐[2]benzopyrano[8a,1‐e]‐1,2,4‐trioxane (24; 5%. Repetition of the last experiment, but replacing acetone by cyclopentanone, gave 17 (16%), (4′aR,7′R,7′aS,10′R,11′aR)‐7′,7′a,8′,9′,10′,11′‐hexahydro‐7′,10′‐dimethylspiro[cyclopentane‐1,3′‐6′H‐[2]benzopyrano[1,8a‐e]‐1,2,4‐trixane] (25; 61%), and (4′aR,7′R,7′aS,10′R,11′aR)‐7′,7′a,8′,9′,10′,11′‐hexahydro‐7′,10′‐dimethylspiro[cyclopentane‐1,3′‐6′H‐[2]benzopyrano[8a,1‐e]‐1,2,4‐trixane] (26, 4%). The X‐ray analysis of 23 was performed, which together with the NMR data, established the structure of the trioxanes 20, 21, 24, 25, and 26. Mechanistic and synthesis aspects of these reactions were discussed in relation to the construction of the 1,2,4‐trioxane ring in arteannuin and similar molecules.
The Conformation of Cycloartenol Investigated by NMR and Molecular Mechanics
Authors: Milon Alain , Nakatani Yoichi , Kintzinger Jean‐Pierre , Ourisson Guy 
Published: December 2004

AbstractCycloartenol (4), a natural plant sterol, was shown to be an effective membrane reinforcer; this was attributed to its conformation. We now present a conformational analysis of 4 by molecular modeling and NMR. Molecular modeling suggests that two conformations I and II coexist, differing mainly at the level of ring C, and of nearly equal energy, I and II each having ring A and B in a chair and half‐chair conformation, respectively, with ring C 1,3‐diplanar in I (solid‐state structure as determined by X‐ray crystallography) and in chair conformation in II. A complete assignment of the 1H‐ and 13C‐NMR spectra of 4 and the entire coupling network in rings A and B is determined by various modern NMR techniques. The conformation of rings A and B thus determined is in agreement with conformations I and II. Low‐temperature NMR experiments show a fast equilibrium between two conformations, presumably I and II. It is concluded, therefore, that the cyclopropane ring of 4 produces a flexibility at the level of ring C which may be important for the membrane properties.
A Nonconcerted Intramolecular Diels‐Alder Reaction of Chiral Allenic‐Acid Derivatives
Authors: Trifonov Latchezar S. , Orahovats Alexander S. 
Published: December 2004

AbstractThe reaction between the chiral allenic acid (+)‐(S)‐1 and the carbodiimides 2a–d and the keten‐imine 6 gives, under mild conditions, the tricyclic compounds 3–5, 7, and 8. Low diastereoselectivity and a partial loss of optical activity are observed. A stepwise mechanistic pathway via a biradical intermediate is postulated.
6‐Thia‐1‐aza‐5λ5‐phosphabicyclo[3.2.0]hept‐3‐ene und Isothiocyanatophosphin‐sulfide aus (Methylidenamino)phosphinen, Schwefelkohlenstoff und Acetylen‐ oder Ethylen‐Derivaten
Authors: Fulde Maria , Ried Walter , Bats Jan W. 
Published: December 2004

6‐Thia‐l‐aza‐5λ5‐phosphabicyclo[3.2.0]hept‐3‐enes and Isothiocyanatophosphine‐sulfides from (Methylidenamino)phosphines, Carbon Disulfide, and Acetylene‐ or Ethylene Derivatives(Methylidenamino)phosphines react with carbon disulfide to 1,3,2‐thiazaphosphete derivatives 2. Acetylenedicarboxylates give with 2 6‐thia‐l‐aza‐5λ5‐phosphabicyclo[3.2.0]hept‐3‐enes 4a, b, and acrylates yield isothio‐cyanatophosphin‐sulfides 5a–c. The structures of 4a and 5a are proven by an X‐ray diffraction analysis.
Formation of the First Trimeric Monoterpenoid Indole Alkaloids
Authors: Schübel Helmut , Fahn Walter , Stöckigt Joachim 
Published: December 2004

AbstractUnder O2, the Aspidosperma alkaloid tabersonine (1) was converted by a crude enzyme preparation from leaves of mature plants of Catharanthus roseus G DON into the trimeric 3‐hydroxy‐14′‐(3α″‐tabersonyl)voafrine B (4) which was easily reduced by NaBH4 to 14′‐(3α″‐tabersonyl)voafrine B ( = tertabersonine; 5). Compounds such as 4 and 5 are the first trimeric alkaloids in the series of monoterpenoid indole alkaloids.
Eine neue Aminoazirin‐Reaktion. Bildung von 3,6‐Dihydropyrazin‐2(1H)‐onen
Authors: Hugener Martin , Heimgartner Heinz 
Published: December 2004

A New Aminoazirine Reaction. Formation of 3,6‐Dihydropyrazin‐2(1H)‐onesThe reaction of 3‐(dimethylamino)‐2H‐azirines 1 and 2‐(trifluoromethyl)‐1,3‐oxazol‐5(2H)‐ones 5 in MeCN or THF at 50–80° leads to 5‐(dimethylamino)‐3,6‐dihydropyrazin‐2(1H)‐ones 6 (Scheme 3). Reaction mechanisms for the formation of 6 are discussed: either the oxazolones 5 react as CH‐acidic heterocycles with 1 (Scheme 4), or the azirines 1 undergo a nucleophilic attack onto the carbonyl group of 5 (Scheme 6). The reaction via intermediate formation of N‐(trifluoroacetyl)dipeptide amide 8 (Scheme 5) is excluded.
Colchicine models: Synthesis and Antitubulin Activity of 2′‐Monosubstituted and 2′, 5‐Disubstituted 2,3,4,4′‐Tetramethoxy‐1,1′‐biphenyls. Synthesis of 4,4′, 5′, 6′‐tetramethoxy‐1,1′‐biphenyl‐2,3′‐dicarboxylic acid
Authors: Itoh Yoshikuni , Brossi Arnold , Hamel Ernest , Flippen‐Anderson Judith L. , George Clifford 
Published: December 2004

AbstractReductive amination of 2,3,4,4′‐tetramethoxtybiphenyl‐2‐carbaldehyde (4) with MeNH2 afforded methylamine 5 (Scheme 1), Hydroxymethylation of amine 8, prepared similarly from 4 by reductive amination with benzylamine followed by N‐methylation, afforded alcohol 12 which was converted the 5‐methyl‐substituted methylamine 14 by conventional chemical reactions (Scheme 2), Methylamine 14 was also obtained from ester 16 after hydroxymethylation to alcohol 17 and conventional manipulation of alcohol and ester functions (Scheme 2). Both amines 5 and 14 as well as the 2′, 5‐dimethyl‐substituted biphenyl 26 prepared from the dialdehyde 25 by a Wolff‐Kishner reduction, did not show noteworthy activity in the tubulin binding assay or as inhibitors of tubulin polymerization (Table). However, the 2′ethyl‐substituted biphebyl 11 prepared from 4 by reaction with MeLi followed by dehyderation and catalytic reduction of styrene 10 (Scheme 1) showed appreciable activity in both assays, coming close to that of known phenyltropolone models. The X‐ray analysis of 14·HCl and 11 showed significant difference in the orientation of the rings with respect to one another (Fig.).
Synthesis of Aristotelia‐Type Alkaloids.. Part IV. Synthesis of (±)‐aristoserratine
Authors: Burkard Stefan , Borschberg Hans‐Jürg 
Published: December 2004

AbstractA convergent diastereoselective synthesis of racemic aristoserratine ((±)‐24) via an intramolecular iminium‐ion cyclization is described. The pivotal imine (±)‐19 was prepared by condensation of the two building blocks (± )‐trans‐8‐amino‐3‐(2,6‐difluorobenzyloxy)‐1‐p‐menthene ((±)‐11) and N‐(p‐methoxybenzenesulfonyl)‐3‐indo‐leacetaldehyde (18) which were synthesized from (±)‐trans‐1‐p‐menthene‐3,8‐diol ((±)‐7) and 3‐indoleacetic acid, respectively. On the route to the target (±)‐24, two previously unknown indole alkaloids have been characterized, namely (±)‐‘anti’‐hobartin‐15‐ol ((±)‐22) and (±)‐‘anti’‐aristotelin‐15‐ol ((±)‐23).
Syntheses of α, β‐Epoxy Silyl Ketones
Authors: Scheller Markus E. , Bernd Schweizer W. , Frei Bruno 
Published: December 2004

AbstractThe synthesis of the α, β‐epoxy‐acylsilanes 1 and 2 starting from the allylic silyl alcohols (E)‐ and (Z)‐3, respectively, by epoxidation with t‐BuOOH/VO(acac)2 followed by oxidation with Collins reagent (CrO3/pyridine) in up to 70% overall yields, is described. The acid‐catalyzed rearrangement of the epoxy‐silyl alcohols 4A + B und 5A + B led to the novel unstable diastereoisomeric α‐silyl‐β‐hydroxy‐aldehydes 9 and 10, respectively. The structure of 10 was established by X‐ray crystal‐structure analysis of the corresponding alcohol 11.
Synthesis of (−)‐Conduritol C (1L‐Cyclohex‐5‐ene‐1,2,3/4‐tetrol)
Authors: Le Drian Claude , Vieira Eric , Vogel Pierre 
Published: December 2004

Abstract(1R, 2R, 4R)‐2‐endo‐Cyano‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐yl acetate ((−)‐7) has been transformed into the all‐cis‐configurated 4L‐4,5,6/0‐trihydroxycyclohex‐2‐en‐1‐one derivatives (−)‐12 and (−)‐19. (−)‐Conduritol C ((−)‐3) was derived in a stereospecific manner from (−)‐12.
Synthesis of Gossypol Analogues
Authors: Ognyanov Vassil I. , Petrov Orlin S. , Tiholov Emil P. , Mollov Nikola M. 
Published: December 2004

AbstractTwo gossypol analogues 2a and 2b were synthesized for biological evaluation as male contraceptive agents. The naphthol 8c was prepared by analogy with a known procedure starling from 3‐isopropylcatechol (3). (t‐Bu)2O2‐Mediated phenolic coupling of 8c furnished the binaphthol 9c which, after pyrane ring closure, deprotection. and selective bisformylation with SnCl4/Cl2CHOCH3, gave the target compound 2a. The corresponding tetrahydroxy analogue 2b was prepared in a similar way.
Synthese von (+)‐Abscisinsäure
Authors: Soukup Milan , Lukáč Teodor , Lohri Bruno , Widmer Erich 
Published: December 2004

Synthesis of (+)‐Abscisic Acid.Starting from (4S)‐4‐hydroxy‐2,6,6‐trimethylcyclohex‐2‐enone (2), a short synthesis of the natural (+)‐abscisic acid ((+)‐1) has been accomplished.
Cyclometalated Compounds of Platinum(II) with two different C, N‐aromatic ligands
Authors: Deuschel‐Cornioley Christine , Lüönd Rainer , von Zelewsky Alex 
Published: December 2004

AbstractA synthetic route leading to bis‐heteroleptic cyclometalated complexes magnified image is described. The complexes [2‐(2′‐thienyl)pyridinato‐N, C‐3′]{2‐[3′‐(trimethylsilyl)2′‐thienyl]pyridinato‐N, C3′}platinum(II) ([Pt(thpy) (TMS‐thpy)]; I) and (l‐phenylpyrazolato‐N2, C2′)[2‐(2′‐thienyl)pyridinato‐N, C3′]platinum ([Pt(Phpz)(thpy)]; II) are characterized by UV/VIS, NMR, and mass spectroscopy. Thermal and photochemical oxidative addition reactions yield two out of the 10 possible pairs of enantiomers of octahedral Pt(IV) compounds.
Stereoselectivity in Reactions of Metal Complexes. Part XI. 2,6‐Bis(pyrrolidin‐2‐yl)pyridine: Synthesis and resolution of the meso and the optically active isomers. Complex formation with copper(II) ion in aqueous solution
Authors: Bernauer Klaus , Gretillat François 
Published: December 2004

AbstractThe new linear triamine 2,6‐bis(pyrrolidin‐2‐yl)pyridine (II) has been synthesized, and the (R, S)‐, (R, R)‐, and (S, S)‐isomers have been separated. Compared to other triamines showing a similar structure, these new ligands form very stable Cu2+ complexes. No significant difference is observed between the meso and the racemic forms for their binary or ternary mixed‐ligand complexes with the amino acids alanine and proline.
Röntgenstrukturanalyse von 2,4,6‐Tri(tert‐butyl)phenyl‐lithium · N,N,N′,N′‐Tetramethylpropan‐1,2‐diamin: Eine monomere Organolithium‐Verbindung
Authors: Maetzke Thomas , Seebach Dieter 
Published: December 2004

X‐Ray Crystal‐Structure Analysis of 2,4,6‐Tri(tert‐butyl)phenyllithium · N,N,N′,N′‐Tetramethylpropane‐1,2‐diamine: a Monomeric Organolithium CompoundTri(tert‐butyl)phenyllithium is an important reagent for the preparation of derivatives of main‐group elements with low coordination state as well as a highly hindered base for the generation of amine‐free Li‐enolates. Its monomeric nature in solution was previously deduced from NMR measurements. While Et2O, THF, and N,N,N′,N′‐tetramethylethylene‐1,2‐diamine (tmen) led to crystalline samples which were not suitable for structure analysis, the N,N,N′,N′‐tetramethylpropane‐1,2‐diamine (tmpn) gave good single crystals of the title compound from Et2O/hexane (disorder along the two‐fold crystallographic axis running through LiC(1) and C(4) of the Ph ring. The structure (Fig. 1, Table 1) has some remarkable features: (i) it is one of the very few monomeric organolithium compounds so far, (η1‐Li on aromatic ring); (ii) it has the rare trigonal‐planar coordination of the Li‐atom; iii) there are close contacts between the Li‐atom arid one of the Me groups in each ortho‐position (Fig. 3). The internal angle on the Ph‐ring ipso‐C‐atom is 114°. This angle as well as those of the other known phenyllithium (Table 2), ‐magnesium, and ‐aluminum structures are included in a plot of ipso‐angles against Pauling electronegativities (Fig. 2).