1.3] -Hydroxylwanderung bei Radikalkationen von Allen-und Acetylenalkoholen/[1,3]-Hydroxyl Migration in Cation Radicals of Allene and Acetylene Alcohols

Abstract

Abstract Contrary to previous conclusions it is shown that the molecular ions of 1, 2, and 3 do not interconvert prior to dissociation. Investigation of labelled compounds establishes a new typ of intramolecular [1,3]-hydroxyl migration to allenic and acetylenic carbons. It is shown that both 1 and 2 undergo irreversible rearrangement to an a,β-unsaturated ketone 4. Methyl loss from the intermediate 4, which accounts for 90% of the total methyl elimination, is preceded by partial hydrogen exchange processes between the three methyl groups of 4. The actual dissociation can be described as an a-cleavage to the carbonyl function. The unusual formation of CH3CO+ " is shown to occur exclusively from 1. However, it is demonstrated that prior to CH3CO+ formation 1 rearranges to m. The mechanistic details of this as well as alternative processes are discussed.