Wagner‐Meerwein Rearrangement

AbstractThe class of 1,2‐rearrangement of carbocation intermediates, from which the migratory group rearranges from an adjacent carbon atom to the carbocation center to form a more stable carbocation or to alleviate the ring strain, is generally known as the Wagner–Meerwein rearrangement. The Wagner–Meerwein rearrangement is generally observed in fused cyclic compounds, such as bicyclic terpene systems. In general, this rearrangement can be initiated under different conditions, which promote the generation of carbocation intermediates. However, due to the carbocationic nature of the rearrangement, this rearrangement sometimes leads to a complicated mixture of products. The modifications for this reaction include the photolysis, thermolysis ofazo‐compounds, and radical initiation of epoxide by Cp2TiCl andazo‐compound by triphenyl pyrylium tetrafluoroborate. This reaction has been broadly applied in organic synthesis.