Benoiton &, Int. J. Peptide Protein Res. 42, 278-283, 1993
"Preparation of activated esters of N-alkoxycarbonylamino acids by
modification of the mixed anhydride procedure"
Prepare the mixed anhydride. Purify it by washing with aqueous solution.
It DOES NOT react with the phenol.
But it does react efficiently if you convert it to the phenoxide anion by
adding a catalytic amount of tertiary amine.
We did NOT prepare any phenyl esters this way, but I don't see why the
method would not work for you.
Remember, Newer methods are not necessarily superior to the old reliables.
Regards Leo B.
At 06:47 PM 98/5/7 +0100, you wrote:
>Hello!
>
>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
>
>
>
N. Leo Benoiton
Department of Biochemistry
University of Ottawa
Ottawa, Ontario, Canada K1H 8M5
Tel: 613 562 5800, Ext. 8216
Fax: 613 562 5440
eMail: benoiton@uottawa.ca