Remarkably stable iron porphyrins bearing nonheteroatom-stabilized carbene or (alkoxycarbonyl)carbenes :  isolation, x-ray crystal structures, and carbon atom transfer reactions with hydrocarbons

摘要

Reactions of [Fe(TPFPP)] (TPFPP = meso-tetrakis(pentafluorophenyl)porphyrinato dianion) with diazo compounds N2C(Ph)R (R = Ph, CO2Et, CO2CH2CHCH2) afforded [Fe(TPFPP)(C(Ph)R)] (R = Ph (1), CO2Et (2), CO2CH2CHCH2 (3)) in 65−70% yields. Treatment of 1 with N-methylimidazole (MeIm) gave the adduct [Fe(TPFPP)(CPh2)(MeIm)] (4) in 65% yield. These new iron porphyrin carbene complexes were characterized by NMR and UV−vis spectroscopy, mass spectrometry, and elemental analyses. X-ray crystal structure determinations of 1·0.5C6H6·0.5CH2Cl2 and 4 reveal FeCPh2 bond lengths of 1.767(3) (1) and 1.827(5) Å (4), together with large ruffling distortions of the TPFPP macrocycle. Complexes 2 and 4 are reactive toward styrene, affording the corresponding cyclopropanes in 82 and 53% yields, respectively. Complex 1 is an active catalyst for both intermolecular cyclopropanation of styrenes with ethyl diazoacetate and intramolecular cyclopropanation of allylic diazoacetates. Reactions of 2 and 4 with cyclohexene or cumene produced allylic or benzylic C−H insertion products in up to 83% yield.