Stable Carbenes—Illusion or Reality?

Some ten years ago a graduate student in chemistry would have failed sadly in his masters examination , had he contended that carbenes could be stored in bottles at room temperature. But precisely this is possible with the compounds 1 and 2 , which were recently described by Arduengo et al. and by Bertrand et al. Compound 1 melts only at 240°C, owing to electronic and stereochemical effects. The carbene 2 not only shows carbene reactivity but also reactivity characteristic of phosphaalkynes. R = adamantyl, R′ = i Pr 2 N.