Free radical-mediated ring expansion and related annulations

Electrochemical Reduction of 1-Bromomethyl-2-oxocycloalkane-1-carboxylates at Silver Cathodes in Dimethylformamide: One-Carbon Ring-Expansion Reactions

“…Finally, radical 10 could undergo one-electron reduction, followed by protonation, to form 5a or 5b [Reaction 8]; again this event is unlikely. Reactions 4, 5, and 8 involve the one-electron reduction of a radical intermediate (8,9, and 10, respectively) to generate a carbanion that is subsequently protonated by adventitious water in the system. Evidence for the minor participation of carbanion intermediates in forming the various electrolysis products was obtained from a series of experiments involving electrochemical reduction of 5.0 mM solutions of 1 or 2 at silver gauze cathodes held at -1.00 V in DMF containing 0.10 M TMABF 4 and 50 mM D 2 O.…”

“…These early contributions were quickly followed by work that focused on ringexpansion reactions involving heterocyclic compounds, 4 macrocyclic keto esters, 5,6 and cyclobutanones. [7][8][9] Other research dealing with ring-expansion reactions has been carried out by Baldwin and coworkers, 10,11 by Boger and Mathvink, 12 and by Wang and coworkers. 13 Since the appearance of these early reports dealing with ring-expansion reactions, there has been an interest in achieving these transformations through the use of methodology that obviates the need for harsh reaction conditions and toxic reagents; Bu 3 SnH and its by-products have been shown to be harmful to many organisms.…”

Profile of the “Green Organic and Medicinal Chemistry” research group at the University of Massachusetts Boston

“…His PhD thesis was on the topic of development of new free radical ring-expansion and annulation reactions [5] . After a 2-year research assistant professor appointment at the same university, he joined DuPont Agricultural Chemicals and worked on the discovery of new herbicides and insecticides.…”

Ring Expansion of Cyclobutylmethylcarbenium Ions to Cyclopentane or Cyclopentene Derivatives and Metal-Promoted Analogous Rearrangements

“…The rearrangement of heterocycles fall out the scope of this review, as well as cyclobutene ring rearrangements and radical-mediated ring expansions. 25 2 Ring expansion of cyclobutylmethylcarbenium ions through activation of a carbon-carbon double bond 6 comprise suitable substrates for a cyclobutylmethyl to cyclopentyl rearrangement and are readily accessible through addition of an alkenyllithium reagent to cyclobutanones.…”