ABSTRACT:On the basis of quantum-chemical calculations, it was shown that among six types of active centers (ACs) that can form during the polymerization of butadiene with lanthanide-based catalytic systems, five types (containing electron-accepting chlorine atoms in the coordination sphere of a lanthanide) exhibit a -allyl binding of the terminal unit of a growing polymer chain to a lanthanide atom and function as cis-regulating. The sixth type of ACs is characterized by a -alkyl structure and shows a trans-stereospecificity. This results was used to interpret the data on the microstructure of polybutadiene prepared using NdCl 3 ⅐ 3TBP-Al(iso-C 4 H 9 ) 3 , NdCl 3 ⅐ 3TBP-Mg(n-C 4 H 9 )(iso-C 8 H 17 ) catalytic systems and their combinations (TBP is tributyl phosphate).
Quantum-chemical calculations and in vitro experiments have demonstrated that polysaccharides are able to adsorb mononucleotides due to the formation of hydrogen bonds. The subsequent dehydration of polysaccharide-nucleotide complexes in the physiologically acceptable temperature range results in the creation of "correct" DNA polymers that are "recognized" by the specific DNA-polymerases. DNA fragments abiogenically formed on polysaccharides vary in size and are characterized by a relatively "simple", most probably, tandem structure. This research developed our previous concept of template-based polysaccharide synthesis with the participation of DNA tandem repeats (glycotranscription concept) making it possible to assume the existence of reverse glycotranscription in biological systems. Future research in the direction that we outlined experimentally may lead to a revolutionary approach in modern molecular biology-glycogenomics.
Bridged compoundsBridged compounds Q 0060 Reactions of Grignard Reagents with 1,3-Dicyanoadamantane. -Optimum conditions for the synthesis of monoaddition products (III) are investigated. -(NOVAKOV, I. A.; ORLINSON*, B. S.; SAVEL'EV, E. N.; URAZBAEV, V. N.; MONAKOV, Y. B.; Russ. Chem. Bull. 52 (2003) 9, 2048-2051; Volgograd State Tech. Univ., Volgograd 400064, Russia; Eng.) -M. Paetzel 16-082
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