I am currently trying to perform a Hydroboration, at scale (300gal) using 9-BBN on a di-allylated raw material. Unfortunately, there seems to be some unpredictability with the level conversion I am getting. Out of 5 batches, only 3 have converted to 100%. One did not convert at all, the other only 30%. Can anyone speak from experience
as to the sensitivity or unpredictable nature of hydroborations using 9-BBN. I am aware of the sensitivity to water of the 9-BBN, thus we have been performing a Karl Fischer to ensure we have plenty of excess reactant before beginning the addition, trying to even stay below 500ppm water. We are using inhibitor free THF as the solvent, and also running under a nitrogen sparge. How sensitive are these systems to the inert-ness/oxygen available? Any other thoughts?