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Long-chain, symmetrically unsaturated ␣,-dicarboxylic acid methyl esters (C 18 , C 20 , C 26 ) were obtained by the catalytic metathetical condensation of 9-decenoic, 10-undecenoic, and 13-tetradecenoic acid methyl esters, respectively, with the homogeneous Grubbs catalyst bis(tricyclohexyl phosphine) benzylidene ruthenium dichloride dissolved in methylene chloride. The dicarboxylic acid esters were epoxidized chemoenzymatically with H 2 O 2 /methyl acetate with Novozym 435 , an immobilized lipase B from Candida antarctica. Polyesters from symmetrically unsaturated or epoxidized ␣,-dicarboxylic acid methyl esters with 1,3-propanediol or 1,4-butanediol, respectively, were achieved by enzymatic polycondensation with the same biocatalyst applied. With 1,3-propanediol as a substrate, the linear unsaturated and epoxidized polyesters had molecular weights of 1950 -3300 g/mol and melting points of 47-75°C, whereas with 1,4-butanediol as a substrate, the resulting polyesters showed higher molecular weights, 7900 -11,600 g/mol, with similar melting points of 55-74°C.

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