Semipinacol rearrangement

A rearrangement in organic chemistry involving a carbocation with a hydroxy group adjacent to the electron deficient center. While similar to the pinacol rearrangement, the semipincaol rearrangement differs from the pinacol rearrangement in that the cation is not formed from a 1,2-diol, but rather from epoxides, β-haloalcohols or β-diazoalcohols (the Tiffeneau-Demjanov rearrangement).