Enantioselective organocatalytic alkylation of aldehydes and enals driven by the direct photoexcitation of enamines.
Disclosed herein is a photo-organocatalytic enantioselective α- and γ-alkylation of aldehydes and enals, respectively, with bromomalonates. The chemistry uses a commercially available aminocatalyst and occurs under illumination by a fluorescent light bulb in the absence of any external photoredox catalyst. Mechanistic investigations reveal the previously hidden ability of transiently generated enamines to directly reach an electronically excited state upon light absorption while successively triggering the formation of reactive radical species from the organic halides. At the same time, the ground state chiral enamines provide effective stereochemical induction for the enantioselective alkylation process.
†ICIQ-Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.
Mattia
M
Silvi
†ICIQ-Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.
Elena
E
Arceo
†ICIQ-Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.
Igor D
ID
Jurberg
†ICIQ-Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.
Carlo
C
Cassani
†ICIQ-Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.|‡ICREA-Catalan Institution for Research and Advanced Studies, Pg. Lluís Companys 23, 08010 Barcelona, Spain.
Paolo
P
Melchiorre