Diazirines: carbene precursors par excellence.

Diazirines are prime precursors for carbenes. In this Account, we discuss the synthetic and mechanistic dimensions that govern the range, availability, and utility of diazirines. We focus on the Graham reaction, which affords halodiazirines from amidines in a one-pot procedure, and the diazirine exchange reaction, which allows easy replacement of an initial diazirine's halo substituent by a variety of other nucleophiles. Together, the Graham reaction and the diazirine exchange reaction provide an extraordinarily wide range of diazirine precurors for electrophilic, ambiphilic, and nucleophilic carbenes.