Rearrangements – Payne rearrangement

NOTE: Important charges and non-bonding electrons are shown throughout the animation except during the transition phase

^{Click the structures and reaction arrows to view the 3D models and animations respectively}

t-BuS^– is a bulky nucleophile, so direct attack on the secondary epoxide is slow. Under basic conditions the neighbouring alkoxide group attacks intramolecularly to make a new, rearranged epoxy alcohol. The new reactive primary electrophilic site undergoes an S_N2 reaction with the t-BuS^– under the conditions of the rearrangement. Notice how the blue OH, which started on carbon 1, has ended up on carbon 2.

G. B. Payne, J. Org. Chem., 1962, 27, 3819–3822.