Solid-phase synthesis of a thymidinyl dipeptide urea library

A thymidinyl dipeptide urea library with structural similarity to the nucleoside peptide class of antibiotics was designed and synthesized. To generate the library, a solid-phase synthesis was developed starting from 5'-azidothymidine attached to a polystyrene butyl diethylsilane (PS-DES) resin support. This study describes the prelibrary solid-phase synthesis development including maximum loading capacity optimization, selection of orthogonal functionalized side-chain protection strategies, synthesis of a 64-member test library, and optimization of the final cleavage step. Using the optimized procedures, we synthesized a 1000-member library in a 50 micromol quantity using IRORI-directed sorting technology in MiniKans, producing the target library in good yields and purity.