New polymer syntheses, 3. Binding of nucleosides to basic polypeptides via isocyanato-isothiocyanates

New aliphatic α-isocyanato-ω-isothiocyanates of various chain lengths were synthesized from ω-isothiocyanatocarboxylic acid chlorides and trimethylsilyl azide. The 5′-OH group of 2′-O,3′-O-isopropylideneuridine and of N⁶-benzoyl-2′-O,3′-O-isopropylideneadenosine was added selectively onto the isocyanate group of aromatic and aliphatic α-isocyanato-ω-isothiocyanates. The isothiocyanate group of the resulting nucleoside derivatives was then reacted with the free amino groups of polylysine, isopolylysine, polyornithine and isopolyornithine. The resulting polypeptides with pending nucleosides were characterized by elemental analyses and 360 MHz ¹H NMR spectra. A new “one-pot-procedure” was developed to protect the primary amino group (N⁶) of 2′-O,3′-O-isopropylideneadenosine.