We are trying to esterify Boc-Pro to the hydroxyl of Boc-Tyr-OtBu. So
far all attempts seem to be fruitless. We have tried many kinds of
COOH activation, from simple DCC to the newest reagents (PyBOP, TFFH,
uronium salts); we've also added bases (DMAP, DIEA, DBU). By HPLC, all
reactions show no change from starting materials. What are we doing
wrong? Could someone point us to useful references in this respect?
Thank you very much!
-- David Andreu University of Barcelona, Spain Phone/Fax: 343-402 1260 andreu@admin.qo.ub.es