From: Marino Tadeu Fabi (mtadeu$##$mpc.com.br)
Date: Fri Oct 13 2000 - 17:51:07 EDT
Dear people,
> I'm protecting an NH2 from an aminoacid (l- asparagine) with tosyl group.
This goes well and after three steps in my synthesis where I've constructed
a substituted tertbutylcarboxamide from this tosylasparagine, I need to
take out the tosyl group without racemizing the amino acid and with a good
yeld.
I've tried HBR/HOAC + parahydroxybenzoic acid . With the conditions I've
used the amide group was hydrolized....
Can someone help me proposing other detosylating agent? I've heard about
tiophenol but I did not used because of hygiene aspects.
Does it exist another agent for this desprotection?
Does someone know a good temperature, time condition for HBR/HOAc+
PARAHYDROXYBENZOIC acid that takes out tosyl without influence at the amide
group?
this is very, very important to me at this moment and any help will be very
well considered
thank you
Marino
CSAQ CAMPINAS/ BRAZIL
a secondary amino(diphenylamine) group in a
> molecule using the formation of an amide. The protection step =
(reaction
> with 10% acetic anhidride in acetic acid and a drop of concentrated
> sulfuric acid) works very well but after the intended reaction we are
> unable to hydrolize the amide. We hace tried with 10 % KOH in water =
and
> ethanol, 10% sulfuric and HCl, CO3K2 in CH3OH, t-ButO- in tButOH
> without sucess. Any suggestions? (other than to change the =
protecting
> group).
> Thank you in advance
>=20
__________________
ORGLIST - Organic Chemistry Mailing List
Website / Archive / FAQ: http://www.orglist.net/
List coordinator: Joao Aires de Sousa (jas$##$mail.fct.unl.pt)
This archive was generated by hypermail 2.1.4 : Fri Sep 19 2003 - 12:15:35 EDT