Enantioselective Radical S(N)2-Type Alkylation of Morita-Baylis-Hillman Adducts Using Dual Photoredox/Palladium Catalysis

An enantioselective radical alkylation of 4-alkyl-1,4-dihydropyridines with Morita-Baylis-Hillman (MBH) adducts has been reported. The S(N)2-type products are predominant. This reaction is enabled by dual photoredox/palladium catalysis. The alkylation products are provided in good yields with good regio-and enantioselectivity. The use of Ding's spiroketal-based bis-(phosphine) (SKP) ligand is crucial to achieving satisfactory regio-and enantioselectivity. The resultant alpha,beta-unsaturated ester can be easily reduced to a synthetically useful chiral allyl alcohol.