Diaza-Cope reaction

This competing Diaza-Cope reaction needs a chair-structured geometry to produce the unwanted rearranged by-product. The key to produce these cages in a reasonable amount is to slow down the rate of the Diaza-Cope rearrangement by cooling the reaction and, for CCIO, to remove the condensation by product, such as water. ... 

In an attempt to prepare unsymmetrical bis-Schiff bases of DAMN under conditions mild enough to prevent exchange, Ohtsuka found that the unexpected, concomitant hydrolysis of the nitrile adjacent to the reaction site gave the bis-Schiff bases 131, which underwent a facile diaza Cope rearrangement giving dihydropyrazines in moderate yields, usually as mixtures of 132 and 133 (79JOC4871) (Scheme 48). 

The first step of the reaction is apparently a diaza-Cope rearrangement, followed by tautomer-ization and lactam ring closure. 

Section 17-9) (2) an electrocyclic reaction (a diaza-Cope rearrangement recall Section 22-7) (3) another imine-enamine (in this case, benzenamine) tautomerization (4) ring closure to the heterocycle and (5) elimination of NH3.]... 

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