Manganese-catalyzed substitution of activated aryl halides (X = Cl, Br andF) and aryl ethers by organomagnesium reagents

In the presence of manganese chloride (10%), Grignard reagents readily reac t in THF with aryl bromides, chlorides and even fluorides, as well as aryl methyl ethers bearing in the ortho- or para-position an electron withdrawin g activating group (CN, CH=NR, oxazoline). Aryl and N- or S-alkylmagnesium halides have been used successfully. The reaction is performed under mild c onditions (0 degrees C to room temperature, 30 minutes to 24 hours) and lea ds to cross-coupling products in good yields.