Dear David,
In your recent response to Lisa's question you wrote in connection with
possible aspartimide/piperidide formation:
"HOBt in the piperdine can help to alleviate it, but IMHO, isn't
universal."
This approach to suppressing Asu formation was suggested several times
during the last year discussions and I wonder if there are any relevant
papers or unpublished observations which clearly demonstrate its
effectiveness via parallel experiments?
In my opinion, it is rather pointless to add acidic HOBt (pKa ca. 4.5)
to a huge excess of strong base, piperidine, since all magic properties
of this REAGENT will be lost in case of its complete deprotonation.
Thanks in advance for any new information.
Regards,
Igor Rodionov
Laboratory of Peptide Chemistry
Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry
6 Science Avenue, Pushchino, Moscow Region
142292, Russian Federation
rodionov@fibkh.serpukhov.su
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