Ligand-Less Iron-Catalyzed Aromatic Cross-Coupling Difluoromethylation of Grignard Reagents with Difluoroiodomethane
作者:Hirotaka Motohashi、Miki Kato、Koichi Mikami
DOI:10.1021/acs.joc.9b00585
日期:2019.5.17
Iron-catalyzed cross-coupling difluoromethylations of the Grignardreagents with difluoroiodomethane provide various aromatic difluoromethyl products in good yields, not employing sterically demanding ligands. Difluoromethylations proceed within 30 min at −20 °C with 2.0 equiv of the Grignardreagents and FeCl3 or Fe(acac)3 (2.5 mol %). Mechanistic investigations clarify difluoromethyl radical intervention;
We describe here the coupling to transform aryl phosphine derivatives by the cleavage of unactivated C(aryl)–P bonds with chromium catalysis, allowing us to achieve the reaction with alkyl bromides and arylmagnesium reagentsundermildconditions. Mechanistic studies indicate that catalytic cleavage of unactivated C(aryl)–P bonds is due to the in situ formed reactive Cr, followed by transmetalation
functionalized benzaldehydes under mild conditions. This reaction was promoted specifically by a low-cost and simple CrCl2 salt used as a precatalyst, enabling synchronous activations of ortho-C(aryl)–SMe and ortho′-C(aryl)–H bonds to achieve difunctionalization of benzaldimines. This work provided a strategy for accessing arylated, alkylated, and diarylated benzaldehydederivatives as a result of