in the art see for example greene t w wutz p g m u201c protecting groups in organic synthesis u201d second edition 1991 new york john wiley amp sons inc additionally when a carboxylic acid is reacted with a hydroxy group a mercapto group or an amine group to provide an ester linkage thioester linkage or an amide linkage the carboxylic acid can be activated prior to the reaction for example by formation of the corresponding acid chloride numerous methods for activating carboxylic acids and for preparing ester linkages thioester linkages and amide linkages are known in the art see for example advanced organic chemistry reaction mechanisms and structure 4 ed jerry march john wiley amp sons pages 419 437 and 1281 a polyester of the invention can be formed from a biologically active compound of formula ho u2014 r 1 u2014 oh and from a linker precursor of formula hooc l cooh as illustrated in scheme ii reaction of the hydroxy groups of the biologically active compound with the carboxylic acids of the linker precursor provides a polymer of formula iii which is a polymer of the invention a preferred biologically active dihydroxy compound that can be used to prepare a polyester of the invention is amikacin amphotericin b apicycline apramycin arbekacin azidamfenicol bambermycin s butirosin carbomycin cefpiramide chloramphenicol chlortetracycline clindamycin clomocycline demeclocycline diathymosulfone.