The 42-O-(2-Hydroxy)ethyl on SDZ-RAD esterified compound of this invention can be prepared by initially acylating the hydroxyl group on 42-O-(2-Hydroxy)ethyl or 31-position or both position of SDZ-RAD with an acylating agent having the general structure X???CH2CO2H, where X is a suitable leaving group such as iodine or bromine, in the presence of a coupling reagent, such as dicyclohexlcarbodiimide