properties of these types of compounds are influenced by
the nature of the protecting groups.16 Thus, benzyl carbamate
exchange in 15 for tert-butyl carbamate led quantitatively
to tetrapeptide 17 by hydrogenation with Pd/C in MeOH in
the presence of di-tert-butyl dicarbonate. Tetrapeptide 17
gelified readily (12 mM) in chloroform, whereas 15 did not.
Finally, hydrogenolysis of benzyl carbamate under standard
conditions (H2, Pd/C, MeOH) led to tetrapeptide 16 in 78%
yield.
In summary, we have presented a very versatile synthesis
of highly functionalized enantiopure peptide dendrimers with
C3-symmetry. The influence of the nature and length of the
spacer from the aromatic core and the cyclobutane ring on
the properties of these compounds is currently under study.
The understanding of these factors and the possibility of
further elongation and functionalization of these dendrimers
should allow us to establish a rational synthetic design of
unique molecules for future applications in the field of new
chiral materials.
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Acknowledgment. Financial support from Ministerio de
Ciencia e Innovacio´n (CTQ2007-61704/BQU) and Gener-
alitat de Catalunya (2009SGR-00733) is gratefully acknowl-
edged. R.G.-A. thanks Ministerio de Educacio´n for a PhD
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