A cyclopropanation reaction of allylmethacrylate (1) with ethyldiazoacetate (2) lead to the formation of 2-(2-methyl-acryloyloxymethyl)-cyclopropancearboxylic acid ethyl ester (3) as a mixture of cis/trans isomers in molar ratio 2:1. The cis isomer could be selectively hydrolyzed by use of Pig liver esterase (PLE). An isolated cis-2-(2-methyl-acryloyloxymethyl)-cyclopropanecarboxylic acid (4) exhibited optical activity. The monomer 3 was easily polymerized using AIBN and benzopinacol as free radical initiators at 65 and 130 degrees C, respectively. H-1 NMR and FT-IR analyses confirmed the presence of the chemically stable cyclopropane ring in both monomer and polymers. The obtained polymers were also characterized by GPC and DSC measurements. A depolymerization behaviour was observed heating the polymers at 200-250 degrees C. The regeneration of starting cis/trans isomers of 3 can be taken as a proof of the high thermal stability of the cyclopropane ring (c) 2006 Elsevier Ltd. All rights reserved.