POLYMERS OF MALIC-ACID CONJUGATED WITH THE 1-ADAMANTYL MOIETY AS LIPOPHILIC PENDANT GROUP

Ethyladamantyl malolactonate and butyladamantanamide malolactonate wer e prepared, starting from malic acid, following the usual synthesis ro ute described for different malolactonic acid esters. Despite the ster ic hindrance of both adamantyl groups, the three-step synthesis led to the corresponding lactones with a quite good yield and high purity. O therwise, ethyladamantyl malolactonate has been obtained by chemical m odification of the lateral carboxylic acid function of malolactonic ac id. Both ethyladamantyl malolactonate and butyladamantanamide malolact onate were homopolymerized by anionic ring opening polymerization usin g tetramethylammonium benzoate as initiator. Expected high molecular w eight homopolymers were obtained and characterized by H-1 nuclear magn etic resonance (n.m.r.) and size exclusion chromatography (s.e.c.). Fu rthermore, ethyladamantyl malolactonate was copolymerized with benzyl malolactonate in the molar ratio 5/95. The resulting copolymer was stu died by H-1 and C-13 n.m.r., s.e.c. and differential scanning calorime try. After deprotection of the benzyl protecting groups by catalytic h ydrogenolysis, the corresponding poly(beta-malic acid-co-ethyladamanty l beta-malate) displayed a water solubility. (C) 1997 Elsevier Science Ltd.