Iron and Manganese Catalysts for the Selective Functionalization of Arene C(sp(2) )-H Bonds by Carbene Insertion.

The first examples of the direct functionalization of non-activated aryl sp(2) C-H bonds with ethyl diazoacetate (N2 CHCO2 Et) catalyzed by Mn- or Fe-based complexes in a completely selective manner are reported, with no formation of the frequently observed cycloheptatriene derivatives through competing Buchner reaction. The best catalysts are Fe(II) or Mn(II) complexes bearing the tetradentate pytacn ligand (pytacn= 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane). When using alkylbenzenes, the alkylic C(sp(3) )-H bonds of the substituents remained unmodified, thus the reaction being also selective toward functionalization of sp(2) C-H bonds.