1-(2-(2-(2-(2-Azidoethoxy)ethoxy)ethoxy)ethyl)-3-(3'',6''-dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9''-xanthen-5-yl)thiourea, 95% (CAS# 1402745-37-2) is a versatile compound used as a building block in the synthesis of lectin inhibitors and theranostic vitamin-linker-taxoid conjugates. 1-(2-(2-(2-(2-Azidoethoxy)ethoxy)ethoxy)ethyl)-3-(3'',6''-dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9''-xanthen-5-yl)thiourea can be further functionalized via Click reactions.