[Babcock_Hall]

https://www.cell.com/cell-chemical-biology/pdf/S1074-5521(98)90169-7.pdf
Bogyo and collaborators (Chemistry & Biology June 1998, 5:307-320) used a diethyl sulfonylphosphonate which had a phenol group on sulfur in a Horner reaction.  The phenolic -OH was not protected.  The substrate was a peptide aldehyde, and the base was NaH.  This paper cites a 1997 paper for the reaction conditions, but the 1997 paper does not provide a detailed protocol.  I am thinking about trying a reaction in which the aldehyde would have an unprotected hydroxypyridine group, and I am wondering whether the reaction above is a relevant precedent.  Both the ideal choice of the base and the number of equivalents are of interest.

[Babcock_Hall]

I neglected to explain a few things in my previous comment.  The hydroxyl group was para with respect to the sulfonyl group in the paper I cited in my previous comment.  We are attempting to synthesize a vinyl sulfone from 3-hydroxyisonicotinaldehyde.  Although we were able to get a low but acceptable yield using an isomeric aldehyde in a Knoevenagel reaction, we have only obtained a few milligrams of the product with this aldehyde, which is not enough for our collaborators to use.  That is why we are considering using a Horner Wadsworth Emmons reaction.

[amorapotter]

The Bogyo study is a good starting point, as it shows the feasibility of using unprotected phenols in a similar reaction. However, given the added complexity of your substrate (hydroxypyridine), conducting systematic trials with both NaH and milder bases like DBU is advised to identify the optimal conditions.slope

Would you like assistance in designing a detailed experimental plan for your trials?