A Ligand Structure–Activity Study of DNA‐Based Catalytic Asymmetric Hydration and Diels–Alder Reactions.

Abstract

AbstractA structure–activity relationship study of the first generation ligands for the DNA‐based asymmetric hydration of enones and Diels–Alder reaction in water is reported. The design of the ligand was optimized resulting in a maximum ee of 83 % in the hydration reaction and 75 % in the Diels–Alder reaction, and some guidelines for ligand design were formulated. A comparison between these two reaction classes using salmon testes DNA/Cu2+‐L catalysts, showed that the enantioselectivity in the hydration reaction was not the result of selective shielding of one π face of the enone. In contrast, the structure of the ligand was suggested to be crucial to position and orient the substrate bound Cu2+ complex optimally with respect to the structured first hydration layer of the DNA. Likely, the DNA activates and directs the H2O nucleophile for attack to one preferred π face of the enone.