Azide‐to‐Diazo Transformation Facilitated by Michael Addition via Phosphazide Formation

A new type of Michael addition of thiols and amines to 2-azidoacrylic acid esters through azide-to-diazo conversion is disclosed. This unusual transformation proceeds via 1,4-addition accompanied by N─N bond cleavage of phosphazide intermediates generated in situ from 2-azidoacrylic acid esters and (4-dimethylaminophenyl)di(tert-butyl)phosphine (Amphos) under practical conditions. The high versatility of the resulting Michael adducts enables the synthesis of a wide variety of organonitrogen compounds.