Radical Reactions for Use in Organic Synthesis

The notion that intramolecular free radical carbon-carbon bond-forming reactions might be of use in the synthesis of natural products of modest complexity was introduced by the Julia group in the 1960’s.1 The 1980’s have born witness to a rebirth of this idea and free radical cyclizations are now being used regularly in synthesis design.2,3 Our research in this area has focused on the development α-acylamino radical cyclizations for use in alkaloid synthesis4 and β-acyloxy radical cyclizations for use in terpenoid synthesis.5 The first portion of this lecture will describe the development of such reactions for use in total or partial syntheses of heliotridine (1→2), gelsemine (3→4) and pleurotin (5→6).2 In each case, the radical cyclization accomplishes a carbon-carbon bond construction that would be problematic using classical polar bond-forming reactions.