A dramatic effect of double bond configuration in N-oxy-3-aza Cope rearrangements-a simple synthesis of functionalised allenes

The first examples of low temperature N-oxy-3-aza Cope rearrangements, leading to functionalised allenes are described, where the Z-configuration of the enaminic double bond in the rearranging system proves critical.

E enamines only react at ⩾70 °C.