C–H Bond activation by alumina: facile hydroxylation of chlorins at their saturated β-carbon by molecular oxygen and alumina

Abstract

The mono-hydroxylation of a β-methylene carbon in the pyrroline ring of a chlorin requires only alumina and molecular oxygen as reagents, with good yields (70–80%) of the hydroxy chlorin obtained at room temperature in 2 h; this is the first example of a hydroxylated chlorin that has been prepared in a regiospecific manner starting from a chlorin, and the first demonstration of the mild activation of a C–H bond by alumina for its oxidation into a hydroxy group.