DFT calculations were performed at the M-11L/6-311+G(d,p),SDD//B3LYP-D3/6-31G(d),LANL2DZ(f)) level of theory with SMD solvation (1,4-dioxane). We computed the competing pathways that lead to the formation of 2, the major branched product (R-prod) and its enantiomer (S-prod) (lowest energy pathways are shown Figure ). The Rh(I)aryl intermediate bound to chiral bisphosphine L6 ([Rh]) can undergo syn-or anti-oxidative addition (OA) to either Re or Si face of the allyl phosphonate, depending on which alkene enantioface the metal is coordinated. The anti-oxidative addition has a lower energy barrier (TS1, TS2 with G ‡ of 12.5 and 16.9 kcal/mol with respect to separated species) than the syn-OA pathway (see SI). In these oxidative addition TSs (TS1 & TS2), the forming C-Rh bond is antito the breaking C-O bond, resembling an SN2' nucleophilic addition, giving cationic  3 -Rh complexes (int1 & int2). Alternative, less-stable conformers were computed (see SI).