Asymmetric epoxidation, Michael addition, and triple cascade reaction using polymer-supported prolinol-based auxiliaries

The applicability of polymer-supported diphenylprolinol derivatives in directing either asymmetric epoxidation or Michael addition of suitable alpha,beta-unsaturated substrates has been assessed. Epoxidation of cinnamaldehyde in the solid state give poorer yields and stereoselectivities than in the solution-phase systems. In contrast Michael additions of several aldehyde enolates to 2-nitro-1-arylalkenes gave results that approached or surpassed those in solution, and could be extended successfully to a three-component Michael/Michael/aldol cascade process. Comparisons of the results of pendant- versus crosslinked functionalized resins in these applications were revealing of the benefits and limitations of each, as were attempts to reuse the polymer-bound auxiliaries. (C) 2008 Published by Elsevier Ltd.