Mechanistic aspects of cyclization‐elimination reactions: 2′‐azabenzanilides

Prominent peaks in the mass spectra of 2′‐azabenzanilides appear to involve molecular ion cyclization followed by the loss of CO and then H. Effects of structure on the abundance of these and [MCHO]+ ions indicate that the ring nitrogen provides a radical‐like reactive site for cyclization, and that stabilization in the product ions of the unpaired electron as well as of the ionic site is important for the reaction.