Free-Radical Reactions of Pyrroles

The free radical resulting from hydrogen atom abstraction from the methyl group of N-methylpyrrole has been shown to dimerize, forming 1,1′-ethylenedipyrrole, and to attack the diene system of N-methylpyrrole, giving 1 -methyl-3-(1-pyrrolylmethyl)pyrrole after radical chain transfer. Pyrrole under similar conditions gave 2,2′-(1′-pyrrolinyl)pyrrole. The structure of the latter product indicates that hydrogen atom abstraction occurs at the 2-position of pyrrole and that the pyrrole ring acts as an effective free-radical trap. In addition, the reactivities toward free-radical attack of a number of related compounds have been established and shown to lie in the order N-methylpyrrole > toluene > 4-picoline > benzene for the compounds examined. © 1964, American Chemical Society. All rights reserved.