A simple batch reactor for the efficient multiple use of polymer-bound α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5-dimethanol titanates in the nucleophilic addition of dialkylzinc reagents to aldehydes

A new apparatus for heterogeneous-catalyst-mediated transformations is described. Results for a variety of enantioselective dialkylzinc additions to aldehydes mediated by polymer-bound alpha, alpha, alpha', alpha'-tetraargl-1,3-dioxolane-4,5-dimethanol titanates (pb-Ti-TADDOLs) using this new apparatus are given, In particular the active catalyst:, once prepared, can be used many times with minimal loss of activity or enantioselectivity, The relative rate of reaction using the pb-Ti-TADDOLates as compared to a homogeneous Ti-TADDOLate has also been determined.