“…Nocardicins, however, do not undergo ring opening with aqueous hydroxylamine [97], and monocyclic, N-unprotected b-lactams were stable in boiling liquid NH 3 [98]. Aminolysis of monocyclic Nalkyl b-lactams requires a large excess of NH 3 and long reaction times at elevated temperature and pressure [93] [99], while the analogous ring opening of N-unprotected monocyclic b-lactams has not been reported to date ( [98], for a nucleophilic opening of a N-Boc b-lactam by aqueous NH 3 , see [100]). …”