The development of a novel nucleophilic thio-bromo "Click" reaction, specifically base-mediated thioetherification of thioglycerol with alpha-bromoesters, is reported. Combination of this thio-bromo click reaction with subsequent acylation with 2-bromopropionyl bromide provides an iterative two-step divergent growth approach to the synthesis of a new class of poly(thioglycerol-2-propionate) (PTP) dendrimers. This approach is demonstrated in the rapid preparation of four generation (G1-G4) of PTP dendrimers with high-structural fidelity. The isolated G1-G4 bromide-terminated dendrimers can be used directly as dendritic macroinitiators for the synthesis of star-polymers via SET-LRP. Additionally, the intermediate hydroxy-terminated dendrimers are analogs of other water-soluble polyester and polyether dendrimers. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3931-3939, 2009