Divergent asymmetric reactions of α-alkenyl ketones with β,γ-alkynyl-α-imino esters enabled by chiral phosphoric acids

Divergent asymmetric synthesis provides access to a wide range of isomers from the same starting material by modifying the reaction conditions, which plays an important role in the efficient construction of a structurally diverse molecular library for structure-activity relationship studies. In this work, we present the divergent asymmetric addition of α-alkenyl ketones with β,γ-alkynyl-α-imino esters enabled by chiral phosphoric acid catalysis. Despite the challenging presence of multiple reactive sites in both components, we successfully achieved the regioselective synthesis of both α-1,2-addition α-tertiary amines and γ-1,4-addition allenes with good to high regio-, diastereo- and enantioselectivities by modifying the reaction conditions. Moreover, the stereodivergent asymmetric synthesis of the four allene stereoisomers bearing contiguous central and axial chirality was achieved by adjusting the E/Z configuration of the α-alkenyl ketone substrates. The divergent asymmetric addition of α-alkenyl ketones with β,γ-alkynyl-α-imino esters enabled by chiral phosphoric acid catalyst has been disclosed, which afforded both the α-1,2-addition and γ-1,4-addition products with good to high regio, diastereo- and enantioselectivities. Remarkably, the stereodivergent asymmetric synthesis of all four allene stereoisomers was accomplished by adjusting the E/Z -configuration of α-alkenyl ketones substrates.