Unexpected nucleophilic behaviour of free-radicals generated from α-iodoketones

摘要

The unexpected nucleophilic reactivity of free-radicals generated from α-iodoketones is reported; two different procedures, either employing tin or the more environmentally acceptable ethylsulfone-based coupling reagent 5c have been developed.rnMethodologies based upon radical species occupy an important place in the toolbox of synthetic chemists since many transformations that are not possible via ionic chemistry can be readily accomplished using radical intermediates.rnAs part of a research programme aimed at the development of connective strategies for the efficient assembly of medium-and large-membered rings, α-iodo diketones such as 1 have been prepared (Scheme 1). Disappointingly, the synthetic utility of these compounds proved to be rather limited because of their rapid Lewis and Brensted acid- or base-mediated ring closure to bicycle 2. Since the ionic conditions employed to functionalize iodoketone 1 failed, we decided to explore the reactivity of 1 under radical conditions.