Continuing our studies aimed at A-ring modified vitamin D compounds, we designed novel 19-norcalcitriol derivatives bearing at C-2 pegylated chains of different lengths. The terminal fragments of these substituents contain hydroxyls or moieties possessing nitrogen and/or sulfur atoms capable of transition metal ions complexation. Also, two conjugate-type platinum(II) complexes of 19-norcalcitriol were obtained in which l-methionine served as chelating moiety. The convergent synthesis of the target 19-norcalcitriol analogs involved several steps with the crucial one being condensation of A-ring phosphine oxide and the known Grundmann ketone by Wittig-Horner reaction. Further elaboration of the 2-alkylidene substituent provided all final compounds which were then tested to determine their affinity for the vitamin D receptor and cytotoxic activity.

Department of Biotechnology University of Wroclaw Joliot Curie 14a 50 383 Wroclaw Poland

Department of Chemistry University of Warsaw Pasteura 1 02 093 Warsaw Poland

Laboratory of Growth Regulators Institute of Experimental Botany of the Czech Academy of Sciences and Palacký University Šlechtitelů 27 78371 Olomouc Czech Republic

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