Dicarbonylrhodium(I) complexes of polypyrrole macrocycles. Part 2. Oxidative addition reactions with aldehydes, formates, β-oxo-esters, methyl ketones, and aryl halides

Abstract

Out-of-plane bisdicarbonylrhodium complexes of etioporphyrin I and a monoazaporphyrin undergo oxidative addition reactions with a variety of substrates RX [R = aryl, acyl, arylcarbonyl, alkoxycarbonyl, ethoxycarbonylmethyl, R′COCH₂, or I; X = H or Br (usually) or I or CH₂COMe (in certain cases)]. One rhodium atom is detached from the macrocycle. The remaining R–Rh^III species is captured by the central porphyrin cavity, retaining R, but with loss of X, to give R–Rh^III-etioporphyrin I or -monoazaporphyrin. Several new types of oxidative addition reaction have been observed, including insertion of rhodium into the C_α–H bond of a methyl ketone. The first isolation of stable acylrhodium(III) complexes from the reaction of rhodium(I) complexes with aldehydes is reported, and an improved method for preparing rhodium(III) porphyrins is described.