Robust route for carbonyl-olefin metathesis

Abstract

When organic chemists want to construct six-membered carbon rings, their go-to method is that old stalwart, the Diels-Alder reaction. But when they want to make five-membered rings, the route is less obvious. Chemists at the University of Michigan, Ann Arbor, now report a carbonyl-olefin ring-closing metathesis reaction catalyzed by iron that creates such pentagonal structures with ease. The reaction, says chemistry professor Corinna S. Schindler, who spearheaded the work, has the potential to become a classic reaction in the organic chemist’s repertoire. “It’s easy to do. You don’t need fancy reagents. You can do it in air,” she says. Also the transformation can produce a wide variety of five-membered, and even some six-membered, rings. Although carbonyl-olefin metathesis reactions—in which a C=O bond and a C=C bond switch bonding partners to make a new carbonyl and a new olefin—have been known for decades, most require stoichiometric amounts of transition-metal reagents, which