Jana Günterová

The oxidative cross-coupling of substituted 2-naphthols, part I: The scope and limitations

Abstract Highly selective oxidative cross-coupling of differently substituted 2-naphthols mediated by Cu(II)-tert-butyl amine complexes is described. The “cross”-products are obtained in good to excellent yields and the selectivity up to ⪢90% is observed depending on the substitution of naphthol nuclei. The alternative procedures - the cross-coupling of free naphthols with CuCl(OMe) as well as the coupling of sodium naphtholates with anhydrous copper(II) chloride - were also studied. All these methods enable a simple and high-yield access to the unsymmetrically substituted binaphthols. A successful optical resolution of methyl 2,2′-dihydroxy-1,1′-binaphthalene-3-carboxylate by means of liquid chromatography on triacetyl-cellulose and the subsequent configurational correlation with a binaphthol derivative of known absolute configuration is reported.

Porphyrins covalently bound to polystyrene. II. an efficient model of monooxygenase reactivity

A simple and efficient method for the preparation of metalloporphyrin catalyst bound to benzhydryl amine substituted polystyrene via amide bond was elaborated. Catalytic efficiency of the Fe3+ or Mn3+ metallocomplexes of these porphyrin-benzhydryl amido-polystyrene catalysts was studied at the epoxidation reactions in the systems syrene/iodosobenzene or t-butyl hydroperoxide/pyridine or imidazole (axial ligands). The rate of substrate conversion (turnover of the catalytic centre) as a function of the density of saturation of the benzhydryl amine substitution of the resin is discussed.

The G-patch domain of Mason-Pfizer monkey virus is a part of reverse transcriptase.

ABSTRACT Mason-Pfizer monkey virus (M-PMV), like some other betaretroviruses, encodes a G-patch domain (GPD). This glycine-rich domain, which has been predicted to be an RNA binding module, is invariably localized at the 3′ end of the pro gene upstream of the pro-pol ribosomal frameshift sequence of genomic RNAs of betaretroviruses. Following two ribosomal frameshift events and the translation of viral mRNA, the GPD is present in both Gag-Pro and Gag-Pro-Pol polyproteins. During the maturation of the Gag-Pro polyprotein, the GPD transiently remains a C-terminal part of the protease (PR), from which it is then detached by PR itself. The destiny of the Gag-Pro-Pol-encoded GPD remains to be determined. The function of the GPD in the retroviral life cycle is unknown. To elucidate the role of the GPD in the M-PMV replication cycle, alanine-scanning mutational analysis of its most highly conserved residues was performed. A series of individual mutations as well as the deletion of the entire GPD had no effect on M-PMV assembly, polyprotein processing, and RNA incorporation. However, a reduction of the reverse transcriptase (RT) activity, resulting in a drop in M-PMV infectivity, was determined for all GPD mutants. Immunoprecipitation experiments suggested that the GPD is a part of RT and participates in its function. These data indicate that the M-PMV GPD functions as a part of reverse transcriptase rather than protease.

Intramolecular transfer of axial to central chirality in the strecker reaction. Synthesis and stereochemistry of 5,7-dicyano-6,7-dihydro-5H-dibenz[c,e]azepines

Abstract The reaction of unsubstituted as well as 6,6′-disubstituted biphenyl-2,2′-dicarboxaldehydes with HCN and ammonia or methylamine has been investigated. It has been found that the final reaction step, the addition of HCN to the intermediary cyclic imino nitriles, is a strictly diastereoselective process, yielding always only one of the two diastereoisomers of the title products, the stereoselection being controlled by the chiral twist of the biaryl axis.

C-C Coupling reaction of 1,5-dibromo-2,6-dihydroxynaphthalene with alkali 2-naphthoxide. Opposite effects of counterion coordination and hydrogen bonding on stereoselectivity in the formation of cis- and trans-1,1′:5′,1″-ternaphthyls

Abstract The title reaction yields cis- and trans-2,2′,6′,2″-tetrahydroxy-1,1′:5′,1″-ternaphthyls as the main products. In contrast to non-selective distribution of the stereoisomers in the thermodynamic equilibrium, very high selectivity can be attained under conditions of kinetic control. The observed values of cis-/trans- ratios range between the extremes 94:6 and 6:94, depending on the solvent and counterion employed. The coordination of the metal counterion plays a key role in the reaction performed in toluene, supporting formation of the cis-stereoisomer. When the coordination ability of the counterion is supressed by 18-crown-6, intramolecular hydrogen bonding of the departing bromide group prevails in the stereocontrol, providing support for the trans-stereoisomer formation.