Treatment of vinyl sulfones with 0.1-0.2 eq of Phosphazene base, P2-Et in THF at 25°C affords the corresponding allyl sulfones in high yield. P2-Et has shown clear superiority to both DBU and KO-t-Bu in these reactions.
Jin, Z., Kim, S. H., & Fuchs, P. L. (1996). Phosphazene base P2-Et mediated isomerization of vinyl sulfones to allyl sulfones. Tetrahedron Letters, 37(30), 5247–5248. https://doi.org/10.1016/0040-4039(96)01110-0