[Babcock_Hall]

It's interesting that you should mention that, as well.  We obtained a H-1 NMR spectrum of the starting material.  One of the phenol-type hydrogens was just under 5 ppm, which is within 0.5 ppm of others that I have observed.  The other one was at greater than 10 ppm, not that far from the aldehyde hydrogen.  I have to wonder about hydrogen bonding myself.  However, the protocols that I have been following are for this exact molecule, which suggests that whatever the problem is, it is not insurmountable.

[rolnor]

Yes, if its this shift its hydrogen bonded. That explaines why standard acetylation conditions are not used. I have acylated this type of phenol, if you use DMAP you can do it.

[Babcock_Hall]

I was thinking of setting up a small test reaction with 2.1 moles of DMAP per mole of diol.  I was thinking about trying 2.1 moles of acetic anhydride per mole of diol as well.  That way there will not be much left over anhydride.  I was also thinking about refluxing.

[rolnor]

I think it should work, if not AcCl can be used. You can se that the mono-acetylated derivative will have about the same Rf on TLC because the hydrogen-bonded OH is verylipophilic. The di-acetylated will actually have lower Rf.

[Babcock_Hall]

Both of the protocols that we consulted (they are nearly identical, except for the workup) use about a twofold excess of acetic anhydride over quinol, even accounting for the fact that there are two acetylations.  It is unclear to me how the excess anhydride was removed by these two sets of workers.

One of the two protocols (Salome 2014) used sodium carbonate and concentration under a vacuum.  I am not sure how quickly acetic anhydride hydrolyzes, but that is one possibility.  Another is that they used something other than typical rotary evaporation procedures.  By this I mean they might have gone to higher temperature in their rotary evaporation step, or they might have removed the remaining anhydride under high vacuum.  Their last step was trituration with pentane, and I am not sure what they were trying to remove. 

The other protocol (Klein 2007) used bicarbonate in the wash.  They also said that they used a vacuum.  They did not triturate.

[wildfyr]

Acetic anhydride and acetic acid can be easily removed by vacuum, If you aren't using house vac, but instead a rotary vein pump directly attached to your rotovap, I doubt you'd have to go over 70°C.

Pentane trituration would also remove these I think.

[Babcock_Hall]

A quick update:  We ran a TLC of the cesium ion reaction mixture using 2% acetone as the solvent, and the reaction product has a higher R_f than the starting aldehyde.  This suggests that either mono-acetylation or di-acetylation took place.  We plan to work this up.  We will also try to run a TLC on the original, potassium crude product.
EDT
We have a Welch pump on our rotary evaporator.  But we are now checking the TLC of the first reaction as well, just in case we obtained product without realizing it.
EDT2
The first reaction (with potassium carbonate) also has a higher R_f than the starting aldehyde in the new TLC solvent system.

[Babcock_Hall]

I may have a mixture of mono- and di-acetylated material as my product, as judged by NMR.  I do not presently have conditions to separate the mono-acetylated and di-acetylated forms.  My next step is a Horner Wadsworth Emmons reaction.  I am tempted to try it, but to increase slightly the amount of DBU, which is the base.  Thoughts?

[wildfyr]

Can't you base wash the mono out?

[Babcock_Hall]

Base is used to hydrolyze the ester in some protocols.  I am not sure how fast this reaction is.

[wildfyr]

Just a weak bicarb solution to deprotonate the phenol and transfer to water layer. Ester hydrolysis typically requires some combination of time, heat, or strong base on all but the most sensitive esters.

[Babcock_Hall]

Now that I think about it again, there was a Na₂CO₃ wash in the workup.  One might think that this would remove all of the molecules with a phenolic -OH group, but that did not happen.  The phenolic -OH is probably H-bonding with the carbonyl group; maybe this changed its behavior somehow.

[Babcock_Hall]

We performed two acetylation reactions, and they looked similar by NMR.  We decided to go on to the next step of the overall synthesis.  When we performed TLC on the starting material for this second step (the starting material being the acetylated aldehyde), we observed two spots, with R_f values that were very close to each other.  These are likely to be the mono-acetylated and di-acetylated aldehydes, with the top spot more likely to be the mono-acetylated product on the basis of relative intensities.  Two different solvent systems gave similar results.  It would be quite challenging to separate them by silica gel chromatography, and for whatever reason, the sodium carbonate wash step did not completely remove the monoacetylated compound.  The presumed product of the second reaction has a very different R_f, fortunately for us.

[wildfyr]

There is also using weak NaOH solution. Should bust any H-bonding.