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Materials combining bio-based resource and degradability aspects such as polylactide (PLA) can represent a sustainable alternative to commercially used oil-based plastics. With tin octanoate (Sn(Oct)(2)) as the catalyst of choice for industrial scale PLA production, traces of the toxic heavy metal can be released into the environment, rendering PLA unsuitable for specific applications. Herein we present four new homoleptic zinc Schiff base complexes that offer facile synthesis and can be handled under aerobic conditions. These robust, tetra-coordinated complexes have been tested as catalysts for the ring-opening polymerization (ROP) of lactide and are well suited under industrially relevant conditions. In situ Raman spectroscopy has been used to determine the apparent reaction rate constant (k(app)) for all complexes at 150 degrees C in bulk. For the fastest complex a k(p) of 3.66 +/- 0.14 x 10(-2) L mol(-1) s(-1) was additionally determined. For this catalyst, 71% conversion and a number-averaged molar mass of above 90000 g mol(-1) has been reached within less than 30 min at a monomer-to-initiator ratio ([M]/[I]) of 1000:1. The good polydispersity (D = 1.7) indicates a controllable ROP via the coordination-insertion mechanism (CIM).

A chiral dinuclear zinc complex can effectively catalyse the direct aldol reactions of pyruvic acid ester with various chiral sugar aldehydes, thus functionally mimicking the pyruvate-dependent type II aldolases. Application of sterically hindered aryl esters allows for the elusive aldol reaction of the pyruvate donor with controlled anti-selectivity en route to the short and efficient synthesis of 3-deoxy-2-ulosonic acids. Pyruvic acid ester is here used as a chemical equivalent of phosphoenol pyruvate (PEP) in imitation of the synthetic principle used in nature. The presented biomimetic methodologies use enol formation for the highly efficient and flexible formation of various C6–C9 ulosonic acids. Particularly, efficient and concise syntheses of 3-deoxy-D-erythro-hex-2-ulosonic acid (KDG, overall 50% yield), 3-deoxy-D-ribo-hept-2-ulosonic acid (DRH, overall 53% yield) and 3-deoxy-D-glycero-D-talo-non-2-ulosonic acid (4-epi-KDN, overall 78% yield) are described. This direct efficient application of pyruvic esters does not require additional demasking steps and thus surpassess previously methodologies utilising masked pyruvic synthons such 2-acetylthiazole and pyruvic aldehyde dimethyl acetal.