1,4-Arylalkylation of Butadiene with Aryl Bromides and Amino Acids Enabled by Photo-Induced Chiral Aldehyde/Palladium Catalysis

Butadiene is one of the most important chemical feedstocks used for the construction of value-added molecules. However, much of the existing endeavors have primarily focused on the achiral synthesis. Alternatively, although the aryl radical-involved transformations have been extensively disclosed, the corresponding catalytic asymmetric methodologies remain exceedingly rare. In this study, we present a highly efficient three-component asymmetric 1,4-arylalkylation of butadiene utilizing readily available aryl bromides and NH2-unprotected amino acid esters. This process is facilitated by photoinduced chiral aldehyde/palladium combined catalysis. A diverse array of chiral nonproteinogenic α,α-disubstituted α-amino acid esters with unique structures is generated with 35–81% yields and 71–98% ee values. The resulting products can be easily converted to other structurally diverse α-amino acids. Density functional theory (DFT) calculations indicate that the final enantioselectivity is governed by a synergistic reaction model that encompasses noncovalent interactions between Pd···Br···Zn as well as strong C–H···Br and π···π dispersion interactions.