Copper-Mediated Nazarov Cyclization/1,2-Sigmatropic Rearrangement

Significance

A stereoselective copper-mediated Nazarov cyclization/Wagner-Meerwein rearrangement produces two types of five-membered spirocyclic products depending on the substrate. Substrates containing a cinnamyl substituent lead to products where the substituent migrates after the Nazarov cyclization, whereas substrates with an alkyl substituent undergo hydrogen migration after cyclization. Six-membered spirocycles can also be formed from the corresponding seven-membered-ring starting material. The enantioselectivities for the reaction are low, but unoptimized.