Nonconcerted Cope rearrangement

It has been suggested that another type of diradical two-step mechanism may be preferred by some substrates. Indeed, a nonconcerted Cope rearrangement has been reported. In this pathway, the 1,6 bond is formed before the 3,4 bond breaks ... 

A nonconcerted mechanism of the 3-aza-Cope rearrangement of the enammonium salts has also been proposed by Mariano and coworkers 116a,ft, although the charge-accelerated rearrangements so far discussed proceed via the pericyclic route. The zwitterionic 7V-vinylisoquinuclidines formed from substrates 173 and a propiolate ester rearrange to fused heterocyclic compounds 174 through a stepwise pathway (Scheme... 

A nonconcerted mechanism of the 3-aza-Cope rearrangement of the enammonium salts has also been proposed by Mariano and coworkers although the charge-... 

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