Iron catalyzed cross coupling reactions of aromatic compounds with organometallic reagents.

Abstract

ArR1 [Ar = C6-30 aryl, heteroaryl; R1 = (substituted) alkyl, cycloalkyl, aryl, heteroaryl] were prepd. by reaction of ArX (Ar as above; X = halide, sulfonate, phosphonate) with R1M (R1 as above; M = MgZ, CaZ, ZnZ, MnZ; Z = anionic ligand) in the presence of ≥1 F salts, F complexes contg. Fe in oxidn. states -2 to +3 as catalysts or precatalysts present homogeneously or heterogeneously in the reaction mixt. The invention exhibits substantial advantages over established cross coupling methodol. using Pd or Ni complex catalysts. Expensive and/or toxic noble metal catalysts are replaced by cheap, stable, com. available and toxicol. benign Fe salts or complexes as the catalysts or pre-catalysts, com. attractive aryl chlorides as well as various aryl sulfonates can be used as starting materials, the reaction can be performed under "ligand-free" conditions, and the reaction times are usually very short. Thus, a mixt. of 2-chloroquinoxaline and Fe(acac)3 in THF at -30° was treated with PhMgBr followed by stirring for 30 min. to -5° to give 70% 2-phenylquinoxaline. [on SciFinder(R)]