Alkyl malolactonates as chiral precursors in the macromolecular engineering of polyesters with a controlled architecture

Racemic and optically active 4-alkyloxycarbonyl-2-oxetanones (alkyl malolac tonates) have been prepared starting from malic acid or aspartic acid, and by introducing a chiral alkyl ester group (2-butyl or 3,3-dimethyl-2-butyl) in the course of beta-substituted p-lactones synthesis. Different stereois omers have been obtained and characterized. It has been shown, by using H-1 NMR and chiral Gas Chromatography, diastereosomeric excess as high as 98% could be retained during the synthesis according to the specific experiment al conditions. These new lactones are dedicated to the tailor-making of sem i-crystalline and optically active polymeric materials with a well defined configurational structure and fixed thermal properties.