Staudinger-type lactam process

The mechanism was posmlated to proceed via initial attack of the nucleophilic catalyst 18 to the ketene 15, generating ammonium enolate 140 that subsequently adds to the electron-deficient diazenedicarboxylate 135. Intramolecular ring-closure releases the catalyst and forms the aza-(3-lactam 136 (Figure 3.10). Interestingly, the configuration at the quaternary stereocenter is opposite to that produced in the Staudinger-type lactam process although both are catalyzed by planar-chiral pyridine derivative 18 and believed to proceed via a similar mechanism. 

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