Aerobic Oxidative Coupling of 2-Aminonaphthalenes by Homogenous Nonheme Iron Catalysts
Vlada Vershinin, Li-noy Feruz, Hagit Forkosh, Lina Kertzman, Anna Libman, Jordi Burés, Doron Pappo
Abstract
An efficient and general aerobic oxidative coupling method to prepare 1,1′-binaphthyl-2,2′-diamines (BINAMs) from N -substituted-2-aminonaphthalene ( 1 ) based on [Fe III (cyclen)(Cl) 2 ]Cl catalyst in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) at room temperature is reported. The highly selective conditions were applied to prepare a list of N, N ′-dialkyl-, N, N ′-dibenzyl-, and N, N ′-diaryl-BINAMs with moderate to high yields. Based on mechanistic studies, which include control experiments and variable time normalization analysis, it is suggested that the coupling between [Fe III (cyclen)( 1 )(OOH)] +2 and 2-aminonaphthalene 1 is the key irreversible step in the catalytic cycle.