Combinatorial synthesis of novel thiourea derivatives on a modified poly(ethylene glycol)

Abstract

A modified poly(ethylene glycol) (PEG) has been developed for the soluble polymer-supported combinatorial synthesis of novel thiourea derivatives. Dihydroxy-PEG with an average MW of 4000 was used as soluble polymer supports, a benzoyl residue as spacer, and 4-oxybenzoyl chloride group as the moiety with the reactive functionality. Representative thiourea derivatives were obtained in moderate to high yields with excellent purity from these modified PEG-bound products by cleavage with 6% ammonium water. In each step of the sequence, the PEG-bound products were precipitated in cold Et 2O and the excessive reagents and by-products were removed by simple filtration. The progress of reaction, purities of the isolation and the configuration of the PEG-bound products were easily monitored by TLC, IR and 1H NMR