Nucleic acid base grafted polyethylenimine. Cytosyl pendant groups synthesis and characterization

Abstract

Poly(N-acyl ethylenimine) of various molecular weights was synthesized by the cationic ring-opening polymerization of 2-H-2-oxazoline and 2-methyl-2-oxazoline. Acid hydrolysis afforded the linear poly(ethylenimine) which was used in the following grafting reactions. Vapor pressure osmometry, gel permeation chromatography and viscosity measurements were used to characterize the polymers synthesized. Potassium 2-(cytos-1-yl)propanoate and potassium 3-(cytos-1-yl)butanoate were synthesized in good yield from the nucleic acid base. These cytosyl pendant groups were grafted onto the poly(ethylenimine) using 4-chloro-1-(4-chlorobenzenesulfonyl)benzotriazole, 93% graft, and norborn-5-ene-2,3-carboximido diphenyl phosphate, 70% graft. Grafting of the t -butoxycarbonyl and n -butoxycarbonyl protected cytosyl pendant groups resulted in a 47% and 40% graft, respectively.