ChemInform Abstract: Catalytic Asymmetric Synthesis of Chromene Derivatives by Iminium Ion Catalysis.

The asymmetric cyclization of cyclic β-diketones with α,β-unsaturated aldehydes is efficiently catalyzed by diarylprolinol silyl ethers to afford hydroxychromenone derivatives, e.g. (III), in good yields and enantioselectivities. [ABSTRACT FROM AUTHOR]