Michal Sobkowski
Polish Academy of Sciences
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Featured researches published by Michal Sobkowski.
Tetrahedron Letters | 1994
Jadwiga Jankowska; Michal Sobkowski; Jacek Stawinski; Adam Kraszewski
Abstract A convenient method for the preparation of deoxyribonucleoside and ribonucleoside 3′-H-phosphonate monoesters via transesterification of diphenyl H-phosphonate with suitable protected nucleosides in pyridine is described.
Tetrahedron | 1996
Annika Kers; Inger Kers; Jacek Stawinski; Michal Sobkowski; Adam Kraszewski
Abstract Diphenyl H-phosphonate undergoes under anhydrous reaction conditions a base-promoted disproportionation to triphenyl phosphite and phenyl H-phosphonate. On the basis of 31P NMR data the most likely mechanism for this transformation was proposed. In order to substantiate these findings and to get a deeper insight into the chemistry of aryl H-phosphonate esters, we carried out also some studies on activation of phenyl and diphenyl H-phosphonates with various condensing agents. We found that aryl vs alkyl esters of phosphonic acid often follow different reaction pathways during the activation, and this can most likely be traced back to higher electrophilicity of the phosphorus centre and to higher reactivity of the P-H bonds in aryl H-phosphonate derivatives.
Nucleosides, Nucleotides & Nucleic Acids | 1996
Annika Kers; Inger Kers; Adam Kraszewski; Michal Sobkowski; Tomas Szabó; Mats Thelin; Rula Zain; Jacek Stawinski
Abstract In this paper a short account of our recent research concerning development of new synthetic methods and new reagents for the preparation of DNA and RNA fragments and their analogues is given. #Dedicated to Professor Yoshihisa Mizuno on the occasion of his 75th birthday. ¶Present address: Astra Production Chemicals, S-151 85 Sodertalje, Sweden.
Nucleosides, Nucleotides & Nucleic Acids | 1994
Günther Ott; Luboš Arnold; Jiri Smrt; Michal Sobkowski; Stefan Limmer; Hans-Peter Hofmann; Mathias Sprinzl
Abstract Dimethylaminomethylene was applied as the protecting group for the exocyclic amino groups of adenosine and guanosine in the automated chemical synthesis of oligoribonucleotides on a polymer bound support. The dimethyl-aminomethylene protecting group can be removed at room temperature under conditions where the concomitant loss of the 2′-protection group can be excluded. The transformation of 2′-O-(t-butyldimethylsilyl)-5′-O-(4,4′-dimethoxytrityl) protected nucleosides to 3′-H-phosphonates yields synthons, well suited for the automated chemical synthesis of oligoribonucleotides. Using these H-phosphonate monomers, a coupling time of two minute: is sufficient to obtain average coupling yields of more than 98 %. Synthesized RNA is recognized as a substrate in an enzymatic reaction, forms the expected secondary structures and is suitable for NMR structural investigations.
Nucleosides, Nucleotides & Nucleic Acids | 2006
Michal Sobkowski; Jacek Stawinski; Adam Kraszewski
Recently, we have proposed a new DP/LP stereochemical notation for P-chiral dinucleoside monophosphate analogues that permits simple correlation between spatial arrangement of the substituents and the configuration at the phosphorus center. As an extension of this work, we present here applications of the DP/LP notation to derivatives containing only one nucleoside unit (e.g., alkyl nucleoside phosphodiesters, nucleoside phosphomonoesters, cyclic phosphate derivatives, nucleoside di-, and triphosphates) and to nonnucleosidic phosphorus compounds.
Nucleosides, Nucleotides & Nucleic Acids | 1998
Michal Sobkowski; Adam Kraszewski; Jacek Stawinski
Three methods for the functionalization of oligonucleotides with aminoalkyl moieties have been developed and their efficiencies were evaluated in the preparation of non-radioactive hybridization probes.
Journal of The Chemical Society-perkin Transactions 1 | 1994
Michal Sobkowski; Jacek Stawinski; Anna Sobkowska; Adam Kraszewski
H-Phosphonate diesters undergo transesterification with amino alcohols to afford as primary products the mixed and the symmetrical H-phosphonate esters. Alcohols react similarly but only in the presence of an external base or in a basic solvent. The rate and the course of transesterification strongly depend on the reaction conditions, the reactivity of the H-phosphonate diester used, and the nature of the amino alcohol.
Nucleosides, Nucleotides & Nucleic Acids | 2006
Michal Sobkowski; Jacek Stawinski; Adam Kraszewski
A configuration of ligands around a phosphorus atom in P-chiral dinucleoside monophosphate analogues can be described using DP/LP stereochemical notation, which allows immediate correlation between the notation of configuration and the actual spatial arrangement of the phosphorus ligands. The area of applications of this new stereochemical nomenclature covers dinucleoside units bridged by virtually any type of tri-and tetra-coordinated phosphorus moieties, that is, phosphorothioates, phosphoramidates, phosphoramidites, boranephosphates, methanephosphonates, H-phosphonates, and many others.
Nucleosides, Nucleotides & Nucleic Acids | 2005
Michal Sobkowski; Jacek Stawinski; Adam Kraszewski
A new stereochemical notation for P-chiral nucleotide analogues and related compounds is proposed. In this notation, the names of configurations, designated as D P and L P, are derived from a geometrical relationship, rather than from priority rules, of substituents at the phosphorus centre. This new stereochemical description offers clear advantages over the CIP R/S nomenclature, particularly when used for comparing the influence of absolute configuration at the phosphorus centre on physicochemical and biological properties of oligonucleotide analogues or in stereochemical correlation analysis of P-chiral nucleotide derivatives.
Tetrahedron Letters | 1996
Jacek Cieślak; Michal Sobkowski; Adam Kraszewski; Jacek Stawinski
Abstract Under mild reaction conditions nucleoside aryl H-phosphonate diesters undergo fast and efficient transesterification with suitably protected nucleosides, affording dinucleoside (3′–5′) H-phosphonate diesters.