Strain-release amination

Abstract

Opening one ring to tack on another Curious chemists have long sought to learn just how tightly carbon atoms can be bound together. For instance, it's possible to form a bond between two opposite corners of an already strained four-membered ring to make an edge-sharing pair of triangles. Gianatassio et al. have now devised a general use for these and related molecular curiosities. They show that appropriately modified nitrogen centers can pop open the most highly strained bond, leaving the more modestly strained ring motif intact. In this way, small rings can emerge as a convenient diversifying element in compounds, including new pharmaceutical candidates. Science , this issue p. 241