Silver‐Catalyzed Asymmetric Aldol Reaction of Isocyanoacetic Acid Derivatives Enabled by Cooperative Participation of Classical and Nonclassical Hydrogen Bonds

Abstract

Abstract The silver‐catalyzed asymmetric aldol reaction of isocyanoacetic acid derivatives with aldehydes has been developed by employing a chiral prolinol‐phosphine as a hydrogen‐bond‐donating P,N,O ligand. DFT calculations indicated that the reaction proceeds in a stepwise manner, involving C−C bond forming carbonyl addition and subsequent enantioselectivity‐determining oxazoline ring formation. An O−H⋅⋅⋅O/ sp 3 ‐C−H⋅⋅⋅O two‐point hydrogen bond donated by the prolinol moiety of the ligand activates the aldehyde in the C−C bond formation step and facilitates the subsequent cyclization under stereocontrol by the catalyst. The calculations further suggest that additional nonclassical C−H⋅⋅⋅O hydrogen bonds as well as London dispersion interactions may also participate synergistically in the stereocontrol. magnified image