Enantioselective chlorinative aldol reaction of α-substituted acroleins catalyzed by chiral phosphine oxides

The enantioselective chlorinative aldol reaction of a-substituted acroleins with aldehydes catalyzed by chiral phosphine oxides is described. A hypervalent silicon complex-derived chloride adds to the alpha-substituted acroleins to form the corresponding silyl enol ethers in situ, which subsequently reacts with aldehydes to produce the alpha-chloromethyl aldol adducts bearing a quaternary stereogenic center in good yields and stereoselectivities. When activated by a phosphine oxide catalyst, trichlorosilyl triflate acts as an effective promoter for the chlorinative aldol reaction as well as the chloride source; this discovery enabled the enantioselective chlorinative aldol reaction of alpha-substituted acroleins. (C) 2017 Elsevier Ltd. All rights reserved.