Metalated phosphonates are more reactive than analogous phosphonium ylids (Wittig reagents). The HWE reaction is usually used when the nucleophilic carbon bears a strong anion stabilizing group (CO2Me, COMe, COH, CN, SO2R, SOR). These reagents are trans-selective if the substituents on phosphorus are simple alkoxy groups.
Intramolecular reactions have been successfully used to close large rings. The example below is a key step in the synthesis of Rhyzoxin D. Williams. D. R.; Werner, K. M.; Feng, B. Tetrahedron Lett. 1997, 38, 6825
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© Hans J. Reich