%0 Journal Article
%T CYP3A Mediates an Unusual C(sp2)-C(sp3) Bond Cleavage via Ipso-Addition of Oxygen in Drug Metabolism.
%A Qin X
%A Wang Y
%A Ye Q
%A Hakenjos JM
%A Wang J
%A Teng M
%A Guo L
%A Tan Z
%A Young DW
%A MacKenzie KR
%A Li F
%J Angew Chem Int Ed Engl
%V 63
%N 23
%D 2024 06 3
%M 38574245
%F 16.823
%R 10.1002/anie.202405197
%X Mammalian cytochrome P450 drug-metabolizing enzymes rarely cleave carbon-carbon (C-C) bonds and the mechanisms of such cleavages are largely unknown. We identified two unusual cleavages of non-polar, unstrained C(sp2)-C(sp3) bonds in the FDA-approved tyrosine kinase inhibitor pexidartinib that are mediated by CYP3A4/5, the major human phase I drug metabolizing enzymes. Using a synthetic ketone, we rule out the Baeyer-Villiger oxidation mechanism that is commonly invoked to address P450-mediated C-C bond cleavages. Our studies in 18O2 and H2 18O enriched systems reveal two unusual distinct mechanisms of C-C bond cleavage: one bond is cleaved by CYP3A-mediated ipso-addition of oxygen to a C(sp2) site of N-protected pyridin-2-amines, and the other occurs by a pseudo-retro-aldol reaction after hydroxylation of a C(sp3) site. This is the first report of CYP3A-mediated C-C bond cleavage in drug metabolism via ipso-addition of oxygen mediated mechanism. CYP3A-mediated ipso-addition is also implicated in the regioselective C-C cleavages of several pexidartinib analogs. The regiospecificity of CYP3A-catalyzed oxygen ipso-addition under environmentally friendly conditions may be attractive and inspire biomimetic or P450-engineering methods to address the challenging task of C-C bond cleavages.