1,5‐Allyl Shift by a Sequential Achmatowicz/Oxonia‐Cope/Retro‐Achmatowicz Rearrangement

An unexpected 1,5-allyl shift is discovered for allyl furfuryl alcohol through two-step sequential ring expansion/contraction rearrangement at room temperature, which could be considered as a Woodward–Hoffmann-forbidden formal [3,5]-sigmatropic rearrangement. Mechanistically, it involves Achmatowicz rearrangement, oxonia-Cope rearrangement, and an unprecedented “retro-Achmatowicz” rearrangement.