Large‐Scale Synthesis of New Pyranoid Building Blocks Based on Aldolase‐Catalysed Carbon‐Carbon Bond Formation

A new large‐scale approach to the synthetically versatile chloromethyl‐substituted, α,β‐unsaturated δ‐lactone 3 is described. The synthesis is based on a biocatalytic process performed on an industrial scale. Conjugate addition of C‐, N‐, O‐, and S‐nucleophiles to lactone 3 affords a variety of new pyranoid building blocks in a highly diastereoselective manner. The operational simplicity of the whole sequence allows for preparing these building blocks on an attractive scale.