A short and efficient Julia–Kocienski olefination protocol, based upon the use of chelating agents (18- crown-6 or TDA-1 for K+; 12-crown-4 or HMPA for Li+), was developed. This protocol enhances the (E)- selectivity of the reaction and the desired olefins are obtained generally with >10:1 (E/Z)-selectivity.
Pospisil, J. (2011). Simple protocol for enhanced (E)-selectivity in Julia–Kocienski reaction. Tetrahedron Letters, 52(18), 2348-2352. https://doi.org/10.1016/j.tetlet.2011.02.086 (Original work published 2011)