Asymmetric Michael reaction of 3-homoacyl coumarins with chromone-fused dienes toward enantioenriched coumarin chromone skeletons

Asymmetric Michael reaction of 3-homoacyl coumarins and chromone-fused dienes was developed by employing a chiral squaramide, and a series of coumarin chromone skeletons were furnished in moderate to high yields (up to 99%) and stereoselectivities (up to 98 : 2 dr, 99% ee).