On the compatibility of azides in phosphoramidite-based couplings: synthesis of a novel, convertible azido-functionalized CyPLOS analogue.

With the aim of preparing a library of ion transporters based on a CyPLOS (cyclic phosphate-linked oligosaccharide) backbone, we describe the synthesis of a novel azido-derivatized CyPLOS analogue that is tailored for practical post-synthetic functionalization with a variety of labels. As a prerequisite for the effective preparation of this phosphate-linked macrocycle, the compatibility of azido alcohols as coupling agents in phosphoramidite synthetic protocols was preliminarily investigated in solution by using 31P NMR spectroscopy to monitor the standard coupling of a nucleoside 3'- phosphoramidite with suitable model alcohols and azides.