Oxidatively Triggered Carbon-Carbon Bond Formation In Ene-Amide Complexes

Ene-amides have been explored as ligands and substrates for oxidative coupling. Treatment of CrCl2, Cl2Fe(PMe3)(2), and Cl(2)Copy(4) with 2 equiv of {(2,6-iPr(2)C(6)H(3))(1-(c)Hexenyl)N}Li afforded pseudosquare planar {eta(3)-C,C,N-(2,6-(Pr2C6H3)-Pr-i)(1-(c)Hexenyl)N}(2)Cr (1-Cr, 78%), trigonal {(2,6-iPr2C6H3)(1-cHexenyl)N}(2)Fe(PMe3) (2-Fe, 80%), and tetrahedral {(2,6-iPr(2)C(6)H(3))(1-cHexenyl)N}2Co(py)(2) (3-Co, 91%) in very good yields. The addition of CrCl3 to 1-Cr, and FeCl3 to 2-Fe, afforded oxidatively triggered CC bond formation as rac-2,2'-di(2,6-iPr(2)C(6)H(3)N-)2dicyclohexane (EA2) was produced in modest yields. Various lithium ene-amides were similarly coupled, and the mechanism was assessed via stoichiometric reactions. Some ferrous compounds (e.g., 2-Fe, FeCl2) were shown to catalyze C-arylation of {(2,6-iPr(2)C(6)H(3))(1-cHexenyl)N}Li with PhBr, but the reaction was variable. Structural characterizations of 1-Cr, 2-Fe, and 3-Co are reported.