Synthesis of Poly(aryl propargyl ether) (PAPE) Stars and Evaluation of Their Cytotoxic Properties

Abstract

The synthesis of a series of low generation poly(aryl propargyl ether) (PAPE) stars 1 and 2 from the corresponding linear branches is described. The first generation branches 3 were readily constructed in a three-step sequence based on Grignard addition, Williamson propargylation, and then Sonogashira-Linstrumelle (S-L) coupling reaction. The use of iodinated compound 4 in an S-L key step allows rapid synthesis of higher linear branches. Their subsequent attachment to benzenoid core 6 via an alkylation step efficiently afforded PAPE stars up to two generations 2 containing methoxycarbonyl ester groups at their peripheries. Transesterification of methyl esters under titanium catalysis proved to be effective and gave several functionalized PAPE stars 2. These amino esters and polyhydroxy amide terminated PAPE stars 2 were evaluated for their cytocompatibility. No significant toxicity was detected in a concentration range of 0.1 to 1000 µg/mL.

Key words

poly(aryl propargyl ether) - PAPE stars - transesterification - palladium - alkynes - Sonogashira coupling

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14

As there is no increase in the number of branches from one generation to another, the term ‘hyperbranched stars’ seems to be more appropriate than the term ‘dendrimer’ to characterize our macromolecules.