AbstractA number of phosphorodichloridites (1) carrying various β‐functionalized ethyl protective groups were converted into their corresponding phosphoromorpholido chloridites (2). These were then reacted with 5′‐O‐(dimethoxytrityl)thymidine to give the pertinent phosphoromorpholidites (3). The applicability of these compounds in the synthesis of oligodeoxynucleotides on a solid support has been evaluated using the synthesis of the thymidine