Dihydropyrrolizines. IV. Manganese dioxide oxidation of 1,2-dehydropyrrolizidines

Abstract

1,2-Dehydropyrrolizidine derivatives with 7-OH or 1-CH2OH substituents are readily oxidized by manganese dioxide. The principal products are dihydropyrrolizine derivatives with the hydroxyls still present or changed to carbonyl, or N-(2'-formylethyl)pyrroles resulting from fission of the C7-C8 bond of the pyrrolizidine ring. The several reaction pathways are defined and interpreted on the basis of mechanisms involving formation and fission of manganate esters.