Asymmetric synthesis of chromene skeletons via organocatalytic domino reactions of in situ generated ortho-quinone methide with malononitrile and β-functionalized ketone

Enantioselective organocatalytic domino reactions of in situ generated ortho-quinone methides with malononitrile and beta-functionalized ketones have been developed. This strategy could generate various chiral chromenes in high yields (up to 99%) and stereoselectivities (up to >99 : 1 e.r.) in the presence of 5 mol% of a bifunctional organocatalyst. Gram-scale and useful synthetic transformations of this process are also presented.