Iminium–Allenamine Cascade Catalysis: One‐Pot Access to Chiral 4H‐Chromenes by a Highly Enantioselective Michael–Michael Sequence

Taking the Michael-Michael: A cascade Michael–Michael reaction of aryl or alkyl alkynals, involving an unprecedented iminium–allenamine sequence, is efficiently catalyzed by a chiral diphenylprolinol TBDMS ether, and affords highly functionalized 4H-chromenes in high yields. TBDMS=tert-butyldimethylsilyl.