In the diazirine exchange reaction, a halodiazirine (eg, 1), usually prepared by Graham oxidation'of an amidine, undergoes substitution with nucleophile Y-to furnish a new diazirine (2). 2 Diazirines are prime precursors for carbenes, so the Graham oxidationldiazirine exchange sequence is a powerful preparative tool in the study of~ arbenes.~