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3 Polish Journal of Chemistry

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NMR Studies of Tautomerism and Protonation Patterns in Bis(6-purinyl) Disulfide and Ionic Forms of 6-Mercaptopurine

Pazderski L., Toušek J., Sitkowski J., Kozerski L., Szłyk E

Polish Journal of Chemistry

2007

Vol. 81, nr 2

193-210

1H-13C and 1H-15N HMBC-NMR spectroscopy was applied to study tautomerism and the protonation patterns in 6-mercaptopurine (6mpH) derivatives: bis(6-purinyl) disulfide ((6puS)2), 6-mercaptopurinium cation (6mpH2 + ) and purine-6-thiolate anions (6mp–, 6mp-deH2–). 1H, 13C, 15N resonances were assigned and the respective delta 1H, delta 13C, delta 15N chemical shifts as well as JHC, JHN coupling constants determined. Quantum-chemical NMR calculations by GIAO method (B3LYP/6-31G**//RHF/6-31G*) allowed to evaluate the ratio of N(1), N(3), N(7), N(9)H : N(1), N(3), N(7)H, N(9) tautomeric forms for the DMSO-solvated (6puS)2 molecules as ca. 9:1. The existence of “semi-protonated” 6mpHźH3O+ species, intermediate between 6mpH and 6mpH2 + , and readily oxidized to (6puS)2 was suggested in the DMSO-d6 + HCl solution. Further hydrolysis and oxidation of the formed disulfide lead to the derivatives of purine-6-sulfenic and purine-6-sulfinic acid.

Selective Formation of Isopropyl alfa- and beta-Glucofuranosides in One Pot Reaction from D-Glucose and Propanol-2 Promoted by V2O5

Tyrlik S., Bednarek E., Bocian W., Sitkowski J., Maurin J., Olejnik M., Nalewajko B., Kozerski L.

Polish Journal of Chemistry

2004

Vol. 78 / nr 6

803-814

Reaction of D-glucose with propanol-2 promoted by V2O5 gives rise exclusively to isopropylglucofuranosides. Their tetraacetates were prepared; X-ray structure of one of tetraacetates was determined. 1H and 13C NMR signals assignment was done by COSY and GMBC techniques. Mechanism of selective glucosidation was discussed.

Spectroscopic studies of Zn(II) halides complexes with 5,7-disubstituted derivatives of 1,2,4-triazolo-[1,5a]-pyrimidine

Szłyk E., Grodzicki A., Pazderski L., Sitkowski J.

Polish Journal of Chemistry

1998

Vol. 72, nr 1

55-60

Complexes of ZnX2 (X=Cl, Br, I, SCN) with 5,7-dimethyl-1,2,4-triazolo-[1,5a]-pyrimidine, 5,7-diphenyl-1,2,4-triazolo-[1,5a]-pyrimidine and 5,7-di-tert-butyl-1,2,4-triazolo-[1,5a]-pyrimidine were prepared and characterized by IR (100-4000 cm-1) and 1H, 13C, 15N NMR spectroscopies. Spectral data suggest pseudo-tetrahedral configuration around Zn(II) atom with N-3 bonded heterocycles. Halides and thiocyanates (N bonded) are in terminal positions.