J. Am. Chem. Soc. DOI: 10.1021/jacs.7b06019

Jian-bo Wang, Adriana Ilie, Shuguang Yuan*, and Manfred T. Reetz*

The possibility of a double Walden inversion mechanism of the fluoracetate dehalogenase FAcD (RPA1163) has been studied by subjecting rac-2-fluoro-2-phenyl acetic acid to the defluorination process. This stereochemical probe led to inversion of configura-tion in a kinetic resolution with an extremely high selectivity factor (E >500), showing that the classical mechanism involving SN2 reaction by Asp110 pertains. The high preference for the (S)-substrate is of synthetic value. Wide substrate scope of RPA1163 in such hydrolytic kinetic resolutions can be expected because the reaction of the even more sterically demanding rac-2-fluoro-2-benzyl acetic acid proceeded similarly. Substrate acceptance and stereoselectivity were explained by extensive molecular model-ling (MM) and molecular dynamics (MD) computations. These computations were also applied to fluoroacetic acid itself, leading to further insights.