The photochemistry of metyrapone

Abstract

Metyrapone [2-methyl-1,2-di(3-pyridyl)propan-2-one, 1] undergoes efficient α-cleavage via the n_oπ* triplet. The fate of the resulting acyl and alkyl radicals has been determined by transient studies as well as through the isolation of the final products, quantum yield measurements and trapping studies. Processes previously documented for carbocyclic analogues of 1, such as disproportionation and coupling of the alkyl radicals and recombination to the starting compound are here accompanied by another major process, viz. coupling with attack of the acyl radical on the pyridine ring, which eventually leads mainly to a polymeric material.