Rollover-Assisted C(sp~2)-C(sp~3) Bond Formation

摘要

Rollover cyclo metalation involves bidentate heterocyclic donors, unusually acting as cyclo metalated ligands. The resulting products, possessing a free donor atom, react differently from the classical cyclometalated complexes. Taking advantage of a "rollover"/"retro-rollover" reaction sequence, a succession of oxidative addition and reductive elimination in a series of platinum(ll) complexes [Pt(N,C)(Me)-(PR_3)] resulted in a rare C(sp~2)-C(sp~3) bond formation to give the bidentate nitrogen ligands 3-methyl-2,2'-bipyridine, 3,6-dimethyl-2,2'-bipyridine, and 3-methyl-2-(2'-pyridyl)-quinoline, which were isolated and characterized. The nature of the phosphane PR3 is essential to the outcome of the reaction. This route constitutes a new method for the activation and functionalization of C-H bond in the C(3) position of bidentate heterocyclic compounds, a position usually difficult to functionalize.