Stereoselective allylation of aldehydes on solid support and its application in biology-oriented synthesis (BIOS)

A systematic study on the asymmetric allylation of aldehydes on solid support is reported. Different kinds of chiral allylboron reagents with complementary direction of stereoinduction were applied successfully in this reagent-controlled transformation. The homoallylic alcohol products are generated with high levels of stereoselectivity and in high yields. The crotylation of aldehydes on solid support employing (E)- and (Z)-Ipc₂crotylborane also proceeds with very high levels of stereoinduction and in high yields. Applications of this methodology for the synthesis of compound collections by subsequent modifications of the allylic moiety are described. In particular, a collection of γ- and δ-lactones has been synthesized by means of a cyclo-release approach including a natural product. In addition, a procedure for the long-standing problem of the hydrogenation of double bonds on solid support is reported. We have also demonstrated the feasibility of applying the stereoselective allylation of aldehydes on solid support in an iterative fashion to generate polyol structures.