Rolnor,
I cannot tell you the the EWG, unfortunately : (. Lets just say it is QUITE electron withdrawing ; ) - hence the pKa of 1 on the para amine.
There are other protecting groups used in the literature - FMoc being one. The choice here is to both save money and not use hydrazine hydrate. Hydrazine hydrate is not used in pilot plants unless it is absolutely necessary. Safety is the paramount reason here. Also it would remove a protection and deprotection step from the synthesis. Time and money.
Below is a ref from Organic Letters showing that this can be done. I acknowledge the low yield and absence of an electron with drawing group here - but this ref and the clients current ability to form the amide leads me to believe that this can be done. Will be tricky but order of addition, solubility, ect.. will all be crucial.
With the respect to the phthalimide protecting group - you think this particular acid chloride is more reactive, due to electron withdrawing nature of it beta to the acid chloride, or just stating the reactivity of acid chlorides in general?
One of the issues I do worry about too is intramolecular cyclization to the benzoimidazole - this is also known in the literature. See OL 1,8, 1999, p 1157 and refs.
Phase transfer can be done without a solvent that has water. I have used them to bring salts into organic phase successfully. We have also been able to add benzoyl chloride to a mixture resorcinol (treatment with aq. NaOH (50%) first) and an organic solvent to form the ester in high yields and purity (95%, 97% respectfully). Was shocked at how well it worked. And granted the nucleophile was a phenoxide - far cry reactivity wise from what we are dealing with here.
I 100% agree with you that the reactivity of the amine is the sticking point. Maybe an excess of acyl chloirde (cheap) may help.
Will have to see when (if haha) I do the work.
And the issue is always money - client wants this, sales guy wants that - and then its plopped in your lap to "make it happen" ; )