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  • 1. Girgis, Adel S.
    et al.
    Mabied, Ahmed F.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hegazy, Lamees
    George, Riham F.
    Farag, Hanaa
    Shalaby, ElSayed M.
    Farag, I. S. Ahmed
    Synthesis and DFT studies of an antitumor active spiro-oxindole2015In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 39, no 10, p. 8017-8027Article in journal (Refereed)
    Abstract [en]

    An anti-oncological active spiro-oxindole 7 was synthesized regioselectively via a [3+2]-cycloaddition reaction of azomethine ylide to exocyclic olefinic linkage of 4-piperidone 6, exhibiting properties against diverse tumor cell lines including leukemia, melanoma and cancers of the lung, colon, brain, ovary, breast, prostate, and kidney. Compound 7 crystallizes in the monoclinic system and P21/c space group with four molecules in the unit cell. The structure was also studied by AM1, PM3 and DFT techniques. DFT studies support the stereochemical selectivity of the reaction and determine the molecular electrostatic potential and frontier molecular orbitals.

  • 2.
    Johansson, Tommy
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kers, Annika
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    2-Pyridylphosphonates: A New type of Modification for Nucleotide Analogues2001In: Tetrahedron Letters, ISSN 0040-4039, Vol. 42, no 11, p. 2217-2220Article in journal (Refereed)
    Abstract [en]

    Suitably protected dithymidine H-phosphonates afforded the corresponding dinucleoside 2-pyridylphosphonates upon treatment with N-methoxypyridinium tosylate in acetonitrile in the presence of 1,8-diazabicylo[5.4.0]undec-7-ene (DBU). The reaction was rapid (ca. 5 min), practically quantitative and proceeded stereospecifically, most likely with retention of configuration at the phosphorus centre.

    A simple and efficient protocol for the preparation of a new type of oligonucleotide analogue bearing a 2-pyridylphosphonate internucleotide linkage was developed

  • 3.
    Johansson, Tommy
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Dinucleoside Pyridylphosphonates Involving Palladium(0)-catalysed Phosphorus-carbon Bond Formation as a Key Step2001In: Chemical Communications, ISSN 1359-7345, no 24, p. 2564-2565Article in journal (Refereed)
    Abstract [en]

    Dinucleoside 3-pyridylphosphonates, as well as their 2- and 4-pyridyl positional isomers, have been synthesised using a palladium(0)-catalysed cross coupling strategy

  • 4.
    Johansson, Tommy
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    The Case for Configurational Stability of H-Phosphonate Diesters in the Presence of Diazabicyclo[5.4.0]undec-7-ene (DBU)2001In: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, Vol. 9, no 9, p. 2315-2322Article in journal (Refereed)
    Abstract [en]

    Configurational stability of dinucleoside H-phosphonates and the stereochemical course of their sulfurisation in the presence of diazabicyclo[5.4.0]undec-7-ene (DBU) were investigated using 31P NMR spectroscopy. It was found that under the reaction conditions and irrespective of the type of protecting groups present in the nucleoside moieties, the H-phosphonate diesters investigated did not undergo any detectable epimerisation at the phosphorus centre, and their sulfurisation with elemental sulfur in the presence of DBU, proceeded stereospecifically. Thus, we could not confirm reports from another laboratory on a stereoselective course of sulfurisation of H-phosphonate diesters and the corresponding acylphosphonates in the presence of DBU.

  • 5.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jezowska, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed propargylic substitution with phosphorus nucleophiles2010In: Abstracts of Papers, 240th ACS National Meeting, Boston, MA, United States, August 22-26, 2010, Washington, D C: American Chemical Society , 2010Conference paper (Other academic)
  • 6.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jezowska, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Preparation of arylphosphonates by palladium(0)-catalyzed cross-coupling in the presence of acetate additives: Synthetic and mechanistic studies2009In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 351, no 18, p. 3207-3216Article in journal (Refereed)
    Abstract [en]

    An efficient protocol for the synthesis of arylphosphonate diesters via a palladium-catalyzed cross-coupling of H-phosphonate diesters with aryl electrophiles, promoted by acetate ions, was developed. A significant shortening of the cross-coupling time in the presence of the added acetate ions was achieved for bidentate and monodentate supporting ligands, and for different aryl electrophiles (iodo, bromo and triflate derivatives). The reaction conditions were optimized in terms of amount of the catalyst, supporting ligands, and source of the acetate ion used. Various arylphosphonates, including those of potential biological significance, were synthesized using this newly developed protocol. Some mechanistic aspects of the investigated reactions are also discussed.

  • 7.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johansson, Tommy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jezowska, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed propargylic substitution with phosphorus nucleophiles: efficient, stereoselective synthesis of allenylphosphonates and related compounds2010In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 12, no 20, p. 4702-4704Article in journal (Refereed)
    Abstract [en]

    A new, efficient method is developed, based on a palladium(0)-catalyzed reaction of propargylic derivatives with various phosphorus nucleophiles, to produce allenylphosphonates and their analogues with defined stereochemistry in the allenic and the phosphonate moiety. 

  • 8.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient synthesis of mono-and diarylphosphinic acids: a microwave-assisted palladium-catalyzed cross-coupling of aryl halides with phosphinate2009In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 65, no 50, p. 10406-10412Article in journal (Refereed)
    Abstract [en]

    A general, efficient method for the microwave-assisted synthesis of mono- and diarylphosphinic acids from anilinium phosphinate and aryl halides, using Pd(0) and Xantphos as a supporting ligand, was developed.

  • 9.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Novel, stereoselective and stereospecific synthesis of allenylphosphonates and related compounds via palladium-catalyzed propargylic substitution2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 10, p. 1741-1755Article in journal (Refereed)
    Abstract [en]

    We have developed a novel method for the synthesis of allenylphosphonates and related compounds based on a palladium(0)-catalyzed reaction of propargylic derivatives with H-phosphonate,H-phosphonothioate, H-phosphonoselenoate, and H-phosphinateesters. The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center. Some mechanistic aspects of this new reaction were also investigated.

  • 10.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed C-P bond formation: Mechanistic studies on the ligand substitution and the reductive elimination. An intramolecular catalysis by the acetate group in PdII complexes2008In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 27, no 22, p. 5876-5888Article in journal (Refereed)
    Abstract [en]

    Ligand substitution and reductive elimination of the palladium-catalyzed C−P bond forming cross-coupling were investigated in depth. It was found that for PhPdII(PPh3)2X (X = I, Br, Cl) complexes, a step commonly referred to as ligand substitution commenced with coordination of an H-phosphonate diester, followed by its deprotonation to form an equilibrium mixture of penta- and tetracoordinate palladiumphosphonate intermediates, from which reductive elimination of the product (diethyl phenylphosphonate) occurred. For the acetate counterpart, PhPdII(PPh3)2(OAc), the incorporation of a phosphonate moiety to the complex was preceded by a rate-determining removal of the supporting phosphine ligand, facilitated by an intramolecular catalysis by the acetate group. Both the reaction steps, i.e., formation of palladiumphosphonate intermediates and reductive elimination, were significantly faster for the acetate versus halides containing PdII complexes investigated. Similar observations were found to be true also for bidentate ligand complexes [(dppp)PdII(Ph)X]; however, in this instance, a single palladiumphosphonate intermediate, (dppp)PdII(Ph)(PO(OEt)2), could be observed by 31P NMR spectroscopy. The synthetic and kinetic studies on the cross-coupling reaction of diethyl H-phosphonate with phenyl halides permitted us to elucidate a crucial catalytic role of an acetate group in PdII complexes and to propose two distinctive catalytic cycles, which complemented traditional Pd0/PdII schemes, for the palladium-mediated C−P bond formation.

  • 11.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ziadi, Asraa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Microwave-assisted palladium-catalyzed cross-coupling of aryl and vinyl halides with H-phosphonate diesters2008In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 10, no 20, p. 4637-4640Article in journal (Refereed)
    Abstract [en]

    A general and efficient method for the microwave-assisted formation of the C−P bond was developed. Using a prevalent palladium catalyst, Pd(PPh3)4, a quantitative cross-coupling of various H-phosphonate diesters with aryl and vinyl halides was achieved in less than 10 min. The reactions occurred with retention of configuration at the phosphorus center and in the vinyl moiety. Using this protocol, several C-phosphonates, including those bearing nucleoside and cholesteryl moieties, were prepared in high yields.

  • 12.
    Kullberg, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Nucleoside H-phosphonates XX: Efficient method for the preparation of nucleoside H-phosphonoselenoate monoesters2005In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 10, p. 1668-1674Article in journal (Refereed)
  • 13.
    Kullberg, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Preparation of nucleoside H-phosphonoselenoate monoesters via the phosphinate approach2005In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 24, no 10-12, p. 1627-1633Article in journal (Refereed)
    Abstract [en]

    An efficient entry to nucleoside 3'-H-phosphonoselenoate monoesters via phosphinate intermediates was developed. It involves a reaction of suitably protected nucleosides with triethylammonium phosphinate in the presence of pivaloyl chloride, followed by selenization of the intermediate nucleoside phosphinates with triphenylphosphine selenide, to produce the corresponding nucleoside H-phosphonoselenoates in 86-92% yields.

  • 14.
    Lavén, Gaston
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jezowska, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Preparation of benzylphosphonates via a palladium(0)-catalyzed cross-coupling of H-phosphonate diesters with benzyl halides. Synthetic and mechanistic studies2010In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 34, no 5, p. 967-975Article in journal (Refereed)
    Abstract [en]

    We have developed a new, efficient method for the synthesis of benzylphosphonate andbenzylphosphonothioate diesters via a palladium(0)-catalyzed cross-coupling reaction betweenbenzyl halides and H-phosphonate or H-phosphonothioate diesters, using Pd2(dba)3(CHCl3)as a palladium source and Xantphos as a supporting ligand. Some mechanistic aspects of thesereactions were investigated using 31P NMR spectroscopy.

  • 15.
    Lavén, Gaston
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nilsson, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Silylation-Mediated Transesterification of Phenyl H-Phosphonothioate: A New Entry to Nucleoside H-Phosphonothioate Monoesters2004In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 24, p. 5111-5114Article in journal (Refereed)
    Abstract [en]

    O-Phenyl H-phosphonothioate undergoes a facile transesterification with suitably protected nucleosides upon in situ silylation with tert-butyldiphenylsilyl chloride in pyridine/toluene to produce the corresponding 3'-H-phosphonothioates in good yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).

  • 16.
    Lavén, Gaston
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthetic studies on the preparation of nucleoside 5'-H-phosphonate monoesters under the Mitsunobu reaction conditions2009In: ARKIVOC, ISSN 1424-6376, no 3, p. 20-27Article in journal (Refereed)
    Abstract [en]

    A reaction of suitably protected nucleosides with phosphonic acid in the presence of diethyl azodicarboxylate and triphenylphosphine in pyridine provided in good yields the corresponding 5’-H-phosphonate monoesters.

  • 17.
    Nilsson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kraszewski, Adam
    Institute of Bioorganic Chemistry, Polish Academy of Science.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemical and Stereochemical Aspects of Oxidative Coupling of H Phosphonantes and H-Phosphonothioate Diesters: Reactions with N,N-, N,O- and O,O-Binucleophiles2005In: Letters in organic chemistry, ISSN 1570-1786, Vol. 2, no 2, p. 188-197Article in journal (Refereed)
    Abstract [en]

    Efficient protocols for oxidative coupling of dinucleoside H-phosphonate and dinucleoside Hphosphonothioate diesters with 6-aminohexan-1-ol, hexane-1,6-diamine, and hexane-1,6-diol, promoted by iodine were developed. In the instance of coupling with O-nucleophiles, the presence of t-butyldiphenylsilyl chloride and excess of iodine during oxidative coupling were found to have beneficial effect for these reactions in terms of rates and purity of the formed products

  • 18.
    Nilsson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Controlling Stereochemistry During Oxidative Coupling: Preparation of Rp or Sp Phosphoramidates from One P-Chiral Precursor2004In: Chemical Communications, ISSN 1359-7345, Vol. 22, p. 2566-2567Article in journal (Refereed)
    Abstract [en]

    Stereochemical outcome of oxidative coupling of H-phosphonate diesters with amines, promoted by iodine, can be controlled to obtain the corresponding phosphoramidate diesters with inversion or with retention of configuration at the phosphorus centre

  • 19.
    Nilsson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Oxidative Coupling of H-Phosphonate and H-Phosphonothioate Diesters: Iodine as a Reagent and a Catalyst2002In: Collection Symposium Series, Vol. 5, p. 87-92Article in journal (Refereed)
  • 20. Sobczak, Milena
    et al.
    Johansson, Tommy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bulkowski, Marek
    Sochacki, Marek
    Laven, Gaston
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mikolaczyk, Barbara
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nawrot, Barbara
    Dna oligonucleotides with stereodefined phenylphosphonate and phosphonothioate internucleotide bonds: synthesis and physico chemical properties2012In: ARKIVOC, ISSN 1551-7004, E-ISSN 1551-7012, Vol. Part 4, p. 63-79Article in journal (Refereed)
    Abstract [en]

    Separate diastereomers of suitably protected dithymidine (3',5')-phenylphosphonates and dithymidine (3',5')-phenylphosphonothioates were obtained via a palladium(0) catalysed stereospecific cross-coupling reaction between separate diastereomers of the corresponding dinucleoside H-phosphonates and dinucleoside H-phosphonothioates with iodobenzene. These compounds were converted into the corresponding phosphoramidite building blocks and used for incorporation of P-stereodefined dithymidine phenylphosphonate and phenylphosphonothioate units TxT into DNA oligonucleotide chain. Dodecathymidylates with centrally positioned one (T(9)TxTT(9)) or two modified units (T(8)TxTTxTT(8)) exhibited different affinity towards complementary DNA (dA(20)) or RNA (A(20)) strands depending on stereochemistry at the phosphorus center, as determined by UV melting temperature studies. Oligonucleotides containing the R-P-phenylphosphonate or R-P -phenylphosphonothioate internucleotide linkages exhibited higher binding affinity to the complementary strands than their S-P-counterparts, but slightly lower than the non-modified reference T-20. All phenylphosphonothioate-modified oligonucleotides formed less stable than their oxo-counterparts duplexes. As expected, the cleavage of the oligonucleotides investigated with 3'- and 5'-exonucleases was stalled at the modification site, independently of P-chirality at the modification site.

  • 21. Sobkowski, Michal
    et al.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kraszewski, Adam
    A proposal for a convenient notation for P-chiral nucleotide analogues. Part 4. A relationship between the DP/LP notation and stereochemistry of reactions2009In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 28, no 1, p. 29-42Article in journal (Refereed)
  • 22. Sobkowski, Michal
    et al.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kraszewski, Adam
    Stereochemistry of internucleotide bond formation by the H-phosphonate method. 7. Stereoselective formation of ribonucleoside (R-P)- and (S-P)-3 '-H-phosphonothioate monoesters2010In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 21, no 4, p. 410-419Article in journal (Refereed)
    Abstract [en]

    Ribonucleoside 3'-H-phosphonothioate monoesters exist in the form of (R-P)- and (S-P)-diastereomers. In order to obtain them in good yields and in high stereochemical purity, stereoselective strategies for their preparation were investigated. For the synthesis of the (R-P)-isomer, a stereoselective sulfhydrolysis of an activated nucleoside H-phosphonate was developed, while the monoesters with an (S-P)-configuration were prepared by asymmetric transformation of diastereomeric mixtures of nucleoside 3'-H-phosphonothioates using either a condensation with 9-fluorenemethanol, followed by beta-elimination, or via pivaloylation-hydrolysis reaction sequence. A tentative assignment of the absolute configurations of the obtained diastereomers of 3'-H-phosphonothioate esters was carried out via a stereochemical correlation analysis.

  • 23. Sobkowski, Michal
    et al.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kraszewski, Adam
    The role of nucleophilic catalysis in chemistry and stereochemistry of ribonucleoside H-phosphonate condensation2009In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 33, no 1, p. 164-170Article in journal (Refereed)
  • 24. Sobkowski, Michał
    et al.
    Jankowska, Jadwiga
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kraszewski, Adam
    Unusual stereochemistry of esterification of uridine 3'-H-phosphonothioate2011In: Phosphorus Sulfur and Silicon and the Related Elements, ISSN 1042-6507, E-ISSN 1563-5325, Vol. 186, no 4, p. 952-955Article in journal (Refereed)
    Abstract [en]

    According to 31P-NMR correlation analysis, reactive derivatives of uridine 3'-H-phosphonothioatereact with O-nucleophiles, probably with retention of configuration.

  • 25. Stamatov, Stephan D.
    et al.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    O-Silylated C3-halohydrins as a novel class of protected building blocks for total, regio- and stereocontrolled synthesis of glycerolipid frameworks2010In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 8, no 2, p. 463-477Article, review/survey (Refereed)
    Abstract [en]

    We propose O-silylated C3-halohydrins [1(3)-O-silyl-2-O-acyl-, 1,2(2,3)-O-bis(silyl)-, and 1(3)-O-acyl-2-O-silyl-3(1)-halo-sn-glycerides] as new chirons in the total synthesis of glycerolipid constructs. These are efficiently producible via opening of the oxirane ring of the corresponding glycidyl derivatives and permit (i) displacement of the iodine by a requisite carboxylate in the presence of O-triisopropylsilyl (O-TIPS), O-tert-butyldimethylsilyl (O-TBDMS), and O-acyl substituents; (ii) selective acylation across an appropriate silyloxy system [e. g., O-TBDMS or O-triethylsilyl (O-TES)] of monoesterified haloglycerides; (iii) direct exchange of an O-silyl protection (e. g., O-TBDMS or O-TIPS) for a trichloroacetyl group; (iv) conversion of a terminal TBDMS group into the corresponding trifluoroacetate without affecting O-TIPS-, O-acyl- and iodo functions. The above transformations secure flexible routes to a variety of otherwise difficult-to-access key-intermediates [e.g., 1,2(2,3)-O-bis(acyl)-3(1)-trichloroacetyl-, 1,3-O-bis(acyl)-2-trichloroacetyl-, 1,2(2,3)-O-bis(acyl)-3(1)-O-TBDMS/TIPS-, 1,3-O-bis(acyl)-2-O-TIPS/TBDMS-, 1(3)-O-acyl-2-O-TIPS-, 1,2(2,3)-O-bis(acyl)-3(1)-iodo-sn-glycerols, etc.] and lend themselves to a powerful methodology for the preparation of di- and triacylglycerols as well as glycerol-based cationic lipids. The reactions involved are entirely regio- and stereospecific, avoid acyl migration, and can provide target compounds with a chosen absolute configuration from a single synthetic precursor.

  • 26.
    Stamatov, Stephan D.
    et al.
    -.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry. -.
    Regioselective and stereospecific opening of an oxirane system mediated by trifluoroacetic acid and halide anions. A new direct approach to C3-vicinal halohydrins.: -2007In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, ISSN -, Vol. 48, no -, p. 1887-1889Article in journal (Refereed)
    Abstract [en]

    -

  • 27.
    Söderberg, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Laven, Gaston
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    (31)P NMR AND COMPUTATIONAL STUDIES ON STEREOCHEMISTRY OF CONVERSION OF PHOSPHORAMIDATE DIESTERS INTO THE CORRESPONDING PHOSPHOTRIESTERS2011In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 30, no 7-9, p. 552-564Article in journal (Refereed)
    Abstract [en]

    (31)P NMR spectroscopy was used to investigate a stereochemical course of a nitrite-promoted conversion of phosphoramidate diesters into the corresponding phosphotriesters. It was found that this reaction occurred with almost complete epimerization at the phosphorus center and at the C1 atom in the amine moiety. On the basis of the (31)P NMR data, a plausible mechanism for the reaction was proposed. The density functional theory calculation of the key step of the reaction, i.e., breaking of the P-N bond and formation of the P-O bond, suggested a one-step S(N)2(P) process with retention of configuration at the phosphorus center.

  • 28.
    Wallin, Richard
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Thelin, Mats
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    On the sulfurization of H-phosphonate diesters and phosphite triesters using elemental sulfur2009In: Phosphorus Sulfur and Silicon and the Related Elements, ISSN 1042-6507, E-ISSN 1563-5325, Vol. 184, no 4, p. 908-916Article in journal (Refereed)
  • 29.
    Zmudzka, Katarzyna
    et al.
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Johansson, Tommy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wojcik, Marzena
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Janicka, Magdalena
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Nowak, Marian
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Stawinski, Jacek
    Nawrot, Barbara
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Novel DNA Analogues with 2-, 3- and 4-Pyridylphosphonate Internucleotide Bonds: Synthesis and Hybridisation Properties2003In: New Journal of Chemistry, ISSN 1144-0546, Vol. 27, no 12, p. 1698-1705Article in journal (Refereed)
    Abstract [en]

    Oligothymidylates modified with stereodefined 2-pyridyl-, 3-pyridyl- and 4-pyridylphosphonate moieties at one or two juxtaposed internucleotide positions were prepared, and their avidity towards complementary single stranded DNA and RNA, as well as toward double stranded DNA were evaluated by UV melting temperature and CD studies. It was found that the sense of chirality at the phosphorus centre and the position of the nitrogen atom in the pyridyl ring of a pyridylphosphonate moiety are important factors governing stability of double- and triple-stranded complexes formed by these oligonucleotides. DNA/DNA and DNA/RNA duplexes containing oligothymidylate strands with R-P-pyridylphosphonate units differed only slightly from unmodified reference complexes. In contrast to this, the S-P-pyridylphosphonate derivatives exhibited lower binding affinity than both their R-P-counterparts and the unmodified reference oligonucleotide T-20. Triplexes of oligo(thymidyl pyridylphosphonate)s with hairpin oligomer d(A(21)C(4)T(21)) were found mostly to be thermodynamically slightly more stable in pH 7.4 and less stable in pH 5.0 than non-modified complexes. As expected, oligonucleotides with pyridylphosphonate internucleotide bonds were recognised by 3'- and 5'-exonucleases but the chimeric oligonucleotide chains were not cleaved at the modi. cation sites.

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