Biomedical Engineering Reference
In-Depth Information
R
i+3
CH
2
NH
2
Fmoc-amino a
c
ids
S
R
i+3
S
S
n
n
OMs
S
H
6
7
R
i+2
R
i+2
O
R
i+1
O
O
Fmoc
H
H
i. PIP
ii. BrCH(R)CO
2
H
S
N
Br
S
N
R
i+3
S
R
i+3
S
n
n
9
8
R
i+2
R
i+2
O
O
i+1
O
i. cleavage:
P(C
2
H
5
CO
2
H)
3
R
O
H
H
i+1
R
R
i+3
HN
ii. cyclization:
PS-TMG
N
N
O
H
β
-turn
S
R
i+3
n
10
PS-TMG: polymer-supported tetramethylguanidine
PIP: piperidine
SCHEME 6.2
Generation of a
-turn mimetic library using an intramolecular-cyclative thiol
S
N
2 displacement.
synthesis by conventional peptide activation chemistries. The formation of imines
via condensation of the amino group of resin-bound amino acids with aldehydes
appeared a particularly appropriate reaction, followed by cycloadditions, condensa-
tion reactions, and other nucleophilic additions to give diverse nitrogen heterocycles
(Scheme 6.3).
SCHEME 6.3
Skeletal diversity from the chemistry of imines derived from resin-bound
amino acids.
