Facile synthesis of polyester dendrimer via combining thio-bromo "Click" chemistry and ATNRC

This article reports on developing an efficient synthesis approach to aliphatic polyester dendrimer, poly(thioglycerol-2-propionate) (PTP), by combination of thio-bromo Click chemistry with atom transfer nitroxide radical coupling (ATNRC). Through the one-pot two-step method, linear polystyrene with hydroxyl end groups (l-PS-2OH) was obtained by first atom transfer radical polymerization of styrene and following termination using 4-(2,3-dihydroxypropoxy)-TEMPO (DHP-TEMPO) to capture the PS macroradicals via ATNRC method. Using l-PS-2OH as support, the dendritic repeating units divergently were grown from the hydroxyl end groups via esterification and thio-bromo Click reaction two-step process. In every generation, the resulting intermediates l-PS-d-PTP (G1-G4) can be easily isolated from the excessive unreacted monomers by simple precipitation in ethanol without help of time, labor and solvent consuming column chromatographic purification. At last, cleavage of the alkoxyamine group between the PS support and dendrimer at elevated temperature (125 degrees C) provided the targeted polyester dendrimer PTP up to the fourth generation. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1762-1768