Horner-Wittig HW Reaction

As Stated above, phosphonates react with both aldehydes and ketones, although ketones generally require more vigorous conditions. Long chain aliphatic aldehydes tend to be unreactive, while readily enolizable ketones usually give poor yields of the alkene. 

A wide variety of bases and reaction conditions have been successfully applied to the HWE reaction, including phase-transfer catalysis. 

Like the HWE reaction, the HW reaction gives rise to a phosphinate by-product that is water-soluble and hence readily removed from the desired alkene. 

In cases where is unable to exert a stabilizing effect and a lithium base is used, the intermediates 10 and 11 do not undergo elimination and instead jS- 

The presence of R groups capable of coordinating to lithium (e.g. OMe, NR3) also lowers the Z-selectivity, presumably by altering the structure of the transition state complex. Indeed, in at least one case (last entry of Table 1.3), significant -selectivity is observed [44]. 

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