Comparison of enantioselective reductions using bead and monolith ‘disk’ polymer formulations of CBS catalysts

Two polymer-supported versions of the Corey, Bakshi, and Shibata (CBS) catalyst were prepared and examined. Polymeric beads, with the auxiliary bound in pendant and crosslinked fashion, were prepared utilizing an improved procedure based upon earlier work. Optimization of a procedure for ketone reduction gives results that match those in solution. Attempted reuse gave mixed results. For comparison purposes, CBS functionalized monoliths were formed and tested but performed poorly.