Synthesis of Imidazolyl-group-bearing 5,10,15,20-Tetrakis(a, a, a, a-o-pivalamidophenyl) porphyrinatoiron (II) Derivatives

5,10, 15, 20-Tetrakis(a, a, a, a-o-pivalamidophenyl)porphyrinatoiron(II) derivatives bearing a side chain with a terminal imidazolyl group were synthesized. A formyl group was introduced at the 2-position of the corresponding porphyrinatocopper(II) using Vilsmeier-Haack reaction. The resultant 2-formylporphyrinatocopper(II) was demetallated with sulfuric acid. Treatment of this with sodium borohydride gave the 2-(hydroxymethyl)porphyrin in a quantitative yield. Reaction of this successively, methanesulfonyl chloride, sodium azide, and triphenylphosphine yielded the 2-(aminomethyl)porphyrin. Condensation of the 2-formyl-porphyrin with malonic acid in the presence of piperidine (Knoevenagel reaction) selectively afforded the 2-(trans-2-carboxyethenyl)porphyrin. Using these functionalized porphyrins, 5, 10, 15, 20-tetrakis(a, a, a, a-o-pivalamidophenyl)porphyrinatoiron(II) derivatives bearing a terminal imidazolyl group were prepared.