Fig. 2: DFT study.
From: Catalytic enantioselective nucleophilic desymmetrization of phosphonate esters
Potential energy surface [ΔG (kcal mol−1)] for the enantioselective nucleophilic desymmetrization of the P(V) compound P1 with 2-methyl-6-nitrophenol using the model BIMP catalyst B12-P(Ph)3 computed at the SMD(fluorobenzene)/M06-2X/def2TZVP//SMD(fluorobenzene)/M06-2X/def2SVP level of theory. The reaction was found to proceed in three stages: complexation, nucleophilic attack and elimination from a metastable pentacoordinate intermediate. The rate- (and enantio-) determining step was found to be nucleophilic addition of the phenol to P1 with the TS leading to the (R)-product (TS1-(R)) being more favourable than that leading to the (S)-product (TS1-(S)) by 2.4 kcal mol−1. Gibbs free energies (kcal mol−1) are reported in parenthesis. ArOH, 2-methyl-6-nitrophenol; Ar′OH, 2,4-dimethylphenol; SM, starting material.
