Multiarm organic compounds for use as reversible chain-transfer agents in living radical polymerizations

Generic approaches to the synthesis of multi-thiocarbonyl thio compounds are described. A multi-hydroxy core was condensed with either α-bromophenyl acetic acid or 2-mercaptopropanoic acid in the presence of p-toluenesulfonic acid catalyst to afford the corresponding esters in quantitative yield. Treatment of the bromo esters with sodium methyl trithiocarbonate or the thiols with carbon disulfide, benzyl bromide and triethylamine then affords two series of trithiocarbonates. The process is exemplified by application to mono, di- or tri-pentaerythritol. These multi-thiocarbonyl thio compounds have application as chain-transfer agents in reversible addition fragmentation chain-transfer (RAFT) polymerization as precursors to star polymers.