Ni(COD)2-Catalyzed ipso-Silylation of 2-Methoxynaphthalene: A Density Functional Theory Study

Abstract

Density functional theory has been used for the systematic investigation of the mechanism involved in Ni(COD)2-catalyzed ipso-silylation of 2-methoxynaphthalene. The two fundamental mechanistic pathways, internal nucleophilic substitution and a nonclassical oxidative addition, have been studied. In both pathways, the first equivalent of KOtBu directly reacts with the silyl boronate (Et3SiBpin) to generate the silyl anion surrogate Et3SiK or silylborate [Et3Si-Bpin(OtBu)]K (IN3), which further reacts with Ni(COD)2 to form a substrate–catalyst complex, [(η2-COD)2NiSiEt3]K. The internal nucleophilic substitution reaction pathway proceeds through η2 complexation of nickel with the C(1)═C(2) bond of 2-methoxynaphthalene. Later, nickel connects to ═C(1) through σ-bond formation and coordinates with oxygen of the −OMe group. Simultaneously, the −SiEt3 group approaches ═C(2) possessing −OMe followed by rearomatization which is facilitated by coordination of K+ with nickel and methoxy oxygen. In a nonclassical oxi...