Synthesis of rigid tryptophan mimetics by the diastereoselective Pictet-Spengler reaction of β3-homo-tryptophan derivatives with chiral α-amino aldehydes

Article abstract of DOI:10.1002/psc.2832

The Pictet-Spengler (PS) cyclizations of β³-hTrp derivatives as arylethylamine substrates were performed with L-α-amino and D-α-amino aldehydes as carbonyl components. During the PS reaction, a new stereogenic center was created, and the mixtur

Full text of DOI:10.1002/psc.2832

Research article
Received: 18 July 2015
Revised: 15 September 2015
Accepted: 1 October 2015
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/psc.2832
Synthesis of rigid tryptophan mimetics by the
diastereoselective Pictet–Spengler reaction of
3
β -homo-tryptophan derivatives with chiral α-
amino aldehydes
Marta Slupska, Karolina Pulka-Ziach, Edyta Deluga, Piotr Sosnowski,
Beata Wilenska, Wiktor Kozminski and Aleksandra Misicka*
3
The Pictet–Spengler (PS) cyclizations of β -hTrp derivatives as arylethylamine substrates were performed with L-α-amino and D-α-
amino aldehydes as carbonyl components. During the PS reaction, a new stereogenic center was created, and the mixture of
cis/trans 1,3-disubstituted 1,2,3,4-tetrahydro-β-carbolines was obtained. The ratio of cis/trans diastereomers depends on the ste-
reogenic centre of used amino aldehyde and the size of substituents. It was confirmed by 1H and 2D NMR (ROESY) spectra. The
conformations of cyclic products were studied by 2D NMR ROESY spectra. Products of the PS condensation after removal of
protecting group(s) can be incorporated into a peptide chain as tryptophan mimetics with the possibility of the β-turn induction.
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
Keywords: tryptophan mimetics; building blocks; beta-turn; P-S cyclisation; diastereoselectivity
The PS cyclization of α-Trp derivatives with Z protected α-amino
Introduction
aldehydes (prepared from L-amino and D-amino acids) was per-
Tryptophan is often a key pharmacophore, which determines the
formed in our previous study [17,24,25]. It was found that the
affinity of peptide ligands for their receptors [1,2]. Various
cyclisation was diastereoselective, and for D-amino aldehydes, only
constrained tryptophan analogues or tryptophan containing motifs
cis isomer occurs; for L-amino aldehydes, two isomers were formed
have been utilized to generate highly potent and selective ligands
with the dominance of isomer trans [24,26].
to biological target receptors [3–5]. Cyclic analogues of tryptophan,
β-Amino acids represent an important class of biologically rele-
which introduce local constraints and reduce the flexibility of the
vant molecules. Oligomers composed of β-amino acids can form
indole moiety, are very valuable tools to probe the bioactive confor-
predictable secondary structures stable to metabolic transformations,
mation of the peptide ligands [6–9]. Such rigid compounds may be
and they can mimic α-peptides in peptide–protein interactions
used to replace the natural amino acid residues in the peptide se-
[
25,27,28]. For these reasons, β-amino acids are very useful for
quence to improve biological activity, potency, metabolic stability
and other properties of parent peptides. The usage of the Pictet–
Spengler (PS) reaction [10,11] was one of the possibilities used to
prepare such analogues by freezing the indole moiety in tryptophan
peptidomimetics [29] design [30]. In this paper, we present
the diastereoselectivity studies of PS condensation of L-α-amino and
D-α-amino aldehydes as carbonyl components with methyl ester of
3
3
3
3
L-β -homo-tryptophan (β -hTrpOCH ) and N-terminal L-β -homo-tryp-
3
[12]. The PS reaction is a cyclization based on the reaction between
3
tophan dipeptides (β -hTrpAlaOCH
3 3
and β -hTrpLeuOCH ) as
arylethylamine and carbonyl components. The main advantage of this
reaction is the formation of a product with stable C–C bond in one sin-
gle step [13]. During the PS reaction of tryptophan with aldehyde, a
new ring is formed and stereogenic centre is generated [14–16]. The
products of the condensation containing 1,2,3,4-tetrahydro-β-
carboline skeleton can be obtained as cis/trans isomers. Diastereo-
meric ratio of the products depends on the conditions of the reaction
arylethylamine substrates. We describe the conformation of a newly
created 6-membered ring. We have studied the dependence of the
ratio of the isomeric products on the configuration of aldehyde. These
analogues can be used as rigid dipeptide mimetics, which may be in-
corporated into the peptide sequence to reduce the flexibility of the
peptide chain and probe the bioactive conformation.
β-Turns often play a crucial role in bioactive peptides as a molec-
ular recognition element [31] and initiation sites for protein folding
[17–19] and the structure of the substrates [20–22].
The heterocyclic skeleton of 1,2,3,4-tetrahydro-β-carbolines pos-
sess multiple sites for functionalization. Therefore, they are an ideal
choice for the design of pharmacophore-based libraries in drug
discovery, through the generation of a large number of structurally
diverse compounds [23]. There is also a possibility to incorporate
such 1,2,3,4-tetrahydro-β-carbolines into a peptide chain to obtain
peptidomimetics with rigid analogues of tryptophan.
*
Correspondence to: Misicka Aleksandra, Faculty of Chemistry, University of
Warsaw. E-mail: misicka@chem.uw.edu.pl
Faculty of Chemistry, University of Warsaw, Warsaw, Poland
J. Pept. Sci. 2015; 21: 893–904
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

SLUPSKA ET AL.
[32,33]. The design and synthesis of analogues that can mimic these
cis/trans diastereoisomers. The results of all performed reactions
secondary structural elements is a valuable tool for the study of bio-
active structures of pharmacophore for better understanding the
molecular mechanisms of peptide–proteins or protein–protein in-
teractions and to provide potent therapeutic agents [16,34]. We will
discuss this possibility of the β-turn induction by products of PS
condensation.
are summarized in Table 1.
3
3
3
The PS reactions of all used β -hTrp derivatives (β -hTrpOCH , β -
3
3
hTrpAlaOCH and β -hTrpLeuOCH ) with L-amino aldehydes prefer-
3
3
3
entially led to trans isomers. Only reactions between β -hTrpOCH3
and Z-L-Ala-CHO led to the product with opposite stereoselectivity,
and cis isomer occurs as the main product. The reactions with
D-amino aldehydes were totally selective, and only cis diastereoiso-
mer was formed. The comparison of these results with the study
conducted under the same conditions with α-Trp derivatives and
L-amino and D-amino aldehydes shows that the ratio of cis/trans dia-
stereoisomers is very similar [24,26]. These and our previous results
showed that the ratio of cis/trans diastereomers depended on the
stereogenic centre of amino aldehyde. To explain the difference be-
Results and discussion
3
The synthesis of β -hTrpOCH
3
was accomplished by Arndt-Eistert
3
homologation of L-α-tryptophan [35]. Dipeptides β -hTrpAlaOCH
and β -hTrpLeuOCH were prepared by the standard Boc-procedure
3
3
3
3
tween the stereoselectivity of the PS reaction of L-Ala-CHO with β -
hTrpOCH and dipeptides, we hypothesized the mechanisms of
3
these reactions. The Felkin–Ahn asymmetric induction model and hy-
in solution. α-Amino aldehydes protected by a benzyloxycarbonyl
group (Z), were prepared with good yields via the Ferentz–Castro
procedure [36] and used instantly without purification to avoid ra-
3
drogen bonded intermediate can explain this result (Figure 1).
cemization. The PS cyclizations of different L-β -homo-tryptophan
3
For β -hTrp derivatives, there is a possibility to form two different
derivatives with L-α-amino and D-α-amino aldehydes were per-
formed in the presence of 5 equivalents of TFA and at low temper-
ature to avoid racemization of chiral amino aldehydes (Scheme 1)
pseudocyclic structures: 6-membered and 7-membered. Six-
membered ring is formed when the intramolecular hydrogen bond
links ester group and iminium cation. Such a situation is responsible
[
17,24,37–39]. The reaction was stirred at À40 °C for the first 5 h,
for diastereoselectivity of the PS reaction with Z-L-Ala-CHO. Addi-
and then stirring was continued at room temperature overnight.
3
1
tional -CH
2
- group in β -hTrp main-chain seems to facilitate the hy-
The ratio of stereoisomers was determined by H NMR spectra
drogen bond formation in the 6-membered ring; thus, the amount
of cis isomer is increased (Table 1), comparing with α-Trp [24]. For
L-amino aldehydes with bigger side chains (Z-L-Ile-CHO),
of the crude mixture after the reaction. The diastereomeric prod-
ucts (cis/trans) were separated in a silica gel column. The confor-
mations of the individual isomers were determined by 2D NMR
ROESY spectra. The exchange of magnetization (NOE effect)
among H-1 and H-3 protons was diagnostic for identification of
7-membered ring with an intramolecular hydrogen bond between
iminium cation and Z-group determines the selectivity, and trans
isomer is predominantly formed. For the cis isomer, there is an un-
favorable steric interaction between side chain of amino aldehyde
(R) and iminium nitrogen. The smaller and less branched R, the
higher amount of cis isomer was observed. For D-amino aldehydes,
only a cis isomer was formed because of the unfavorable interac-
tions in the intermediate state leading to the trans isomer (Figure 2).
The conformations of the newly created 6-membered ring were
studied by 2D NMR ROESY spectra. The NOE effect among H-3 and
H-4 protons was crucial for predictions of the ring’s conformation.
For cis isomer, there are two possible twisted chair conformations
(Figure 3), but NOE effect between H-3 and both H-4 protons con-
firmed only the more stable form B with both substituents
equatorially located. All cis isomers adopt the conformation with
both substituents (on C-1 and C-3) equatorially located. For trans
analogs, the results were more variable. For compounds 4a-h ob-
3
tained from β -hTrpOCH3 we observed the NOE effect between
,
1
Table 1. The ratio of cis/trans isomers determined* by H NMR
3
3
3
Amino
aldehyde 2a-h
β -hTrpOCH
cis/trans
3
β -hTrpAlaOCH
3
β -hTrpLeuOCH
cis/trans
3
cis/trans
[
%] 3a-h/4a-h [%] 5a-h/6a-h
[%] 7a-h/8a-h
a
b
c
Z-L-Ala-H
Z-L-Ile-H
60/40
0/100
47/53
0/100
100/0
100/0
100/0
100/0
35/65
0/100
26/73
0/100
100/0
100/0
100/0
100/0
39/61
0/100
21/79
0/100
100/0
100/0
100/0
100/0
Z-L-Phe-H
Z-L-Val-H
Z-D-Ala-H
Z-D-Leu-H
Z-D-Phe-H
Z-D-Val-H
d
e
f
g
h
3
Scheme 1. PS reaction between β -hTrp derivatives and α-amino
aldehydes.
*
before purification
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SYNTHESIS OF RIGID TRYPTOPHAN MIMETICS
3
Figure 1. Hypothesis of the mechanism for PS reaction between β -hTrp derivatives and L-amino aldehydes with (a) smaller side chains, (b) bigger side
chains.
membered and 11-membered. A 9-membered ring is formed when
the intramolecular hydrogen bond links an amino group derived
from aldehyde and oxygen of the carbonyl group in peptide chain
(Figure 4a). An 11-membered ring with an intramolecular hydrogen
bond between oxygen of the Z-group and an amine group in a
peptide chain may also arise (Figure 4b). To confirm these conjec-
tures and find out which of these structures are the most energet-
ically favorable, the optimization using molecular mechanics
(HyperCube, HyperChem 8.0) was performed. We found that the
structure with an 11-membered ring is preferable, which is consis-
tent with literature data for peptidomimetics containing β-amino
acids [42]. The calculated distance between hydrogen and oxygen
was below 2.5 , and between Cα(i) and oxygen, in which our ana-
logues take place Cα(i + 3), was below 7 [40] (Figure 5).
The results of the molecular modeling were confirmed by 2D
NMR ROESY spectra. We observed the NOE effects for analogs 6a
and 7a between protons marked by arrows in Figure 5, which is
in agreement with the modeled structure.
Figure 2. Hypothesis on the mechanism for PS reaction between D-amino
aldehydes and β -hTrp derivatives.
3
H-3 and both H-4 protons, which means that the conformational
equilibrium is shifted to the C form where the -CH COOCH group
2
3
was axially and substituent on carbon C-1 equatorially located. For
trans analogs 6a-h, 8a-h, we observed a strong NOE effect between
H-3 and one of H-4 protons; for second H-4 proton, the effect was
weak or did not occur. These observations indicate that for the pep-
tide chain at C-3, an equatorial position is more preferable then ax-
ial. To sum up, in the case of trans isomers with small C-3
Conclusion
2 3
substituents (-CH COOCH ), the group is axially located; for larger
groups, peptide moieties are equatorially located.
3
In conclusion, our studies have shown that L-β -homo-tryptophan
3
A general definition of a β-turn states that any tetrapeptide chain
in which the distance between the Cα(i) and the Cα(i + 3) is below 7
and which occurs in non-helical region constitutes a β-turn [40]. The
pseudo 10-membered ring often, but not always, is formed by an
intramolecular hydrogen bond between the CO of the first residue
and peptides with N-terminal L-β -homo-tryptophan residue can
be used as substrates for PS cyclization. During the PS reactions be-
3
tween β -hTrp derivatives and L-amino aldehydes cis and trans
products are formed with the dominance of trans isomer with the
3
exception of reaction β -hTrpOCH with Z-L-Ala-CHO. In the reac-
3
(
i) and the NH of the fourth residue (i + 3). According to literature
tion with L-amino aldehydes with side chains branched on carbon
β (Z-L-Ile-H, Z-L-Val-H) only trans isomer is obtained. The PS reac-
tions with D-amino aldehydes are fully selective and only cis diaste-
[26,41] and our previous study [24], it is considered that disubsti-
tuted 6-membered rings in tetrahydro-β-carboline can induce β-
turns. Such structures are more commonly found in trans isomers;
therefore, we speculate that it is possible that trans analogs 6a-h
and 7a-4 can have the ability to form β-turns. Hypothetically, there
is a possibility to form two different pseudocyclic structures: 9-
3
reomer is formed. The C-terminal part of the β -hTrp residue does
not have any influence on the selectivity of the PS reactions, and
3
the results obtained for methyl ester of β -hTrp are the same as
3
for peptides with N-terminal β -hTrp. The conformations of the
J. Pept. Sci. 2015; 21: 893–904
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SLUPSKA ET AL.
Figure 3. The conformations of the newly created 6-membered rings adopted by the (a) cis and (b) trans products of PS cyclization.
The RP–HPLC analysis and purifications were carried out using C12
analytical (Jupiter 4u Proteo 90A, 250× 4,6mm, 4 micron, linear gra-
dient 1: t = 0 min, 97%A, 3%B, t = 20 min, 3%A, 97%B, flow rate
À1
1
mlmin , λ = 254 nm) and C12 semi-preparative (Jupiter 4u
Proteo 90A, 250 × 10 mm, 4 micron, linear gradient 2: t = 0 min,
À1
65%A, 35%B, t = 30 min, 65%A, 35%B, flow rate 3 ml min
,
λ = 254nm) columns on a Shimadzu instrument (Shimadzu,
Duisburg, Germany). The mobile phases (water A, acetonitrile B)
contained 0,05% (v/v) TFA. TLC analysis was performed on pre-
coated plates of silica gel 60 F254. Silica gel 60 (0.063–0.2) was used
for flash chromatography. Mass analyses were performed on a LCT
TOF spectrometer using electrospray ionization (positive ion mode)
or LC–MS (Shimadzu, Duisburg, Germany). NMR spectra were
recorded on Varian NMR System 200 or 700 MHz spectrometers
Figure 4. Hypothetical 9-membered (a) and 11-membered (b)
pseudocyclic forms of β -homo-tryptophan dipeptides.
3
newly created 6-membered ring depends on the size of C-terminal
3
part of β -hTrp residue. In trans isomers small C-terminal substitu-
ents (-CH COOCH ) are axially located, big ones (peptide moieties)
2
3
13
are equatorially located.
(Agilent, Boeblingen, Germany). C NMR spectra were acquired
as 2D HSQC (quaternary and carbonyl carbons were not observed).
Obtained 1,2,3,4-tetrahydro-β-carbolines after removal of
protecting group(s) could be incorporated into a peptide chain to
obtain peptidomimetics with rigid analogues of tryptophan. The
tetrahydro-β-carbolines (6a and 7a) moiety that are incorporated
into the peptide chain may induce β-turn and impose the definite
position of the peptide chains.
3
A methyl ester of β -homo-tryptophan was prepared by standard
3
3
procedures. Dipeptides β -hTrpAlaOCH
3 3
and β -hTrpLeuOCH
were prepared by standard Boc-procedure in solution,
O-(Benzotriazol-1-yl)-N,N,N’,N’-tetramethyluronium tetrafluoro-
borate (TBTU) was used as coupling reagent. The protecting
group Boc was removed in the presence of TFA and then
3
methyl ester of β -homo-tryptophan and dipeptides were con-
Experimental section
verted into free bases by the stirring in the mixture of AcOEt
and saturated solution of NaHCO
was separated, washed with brine and dried over MgSO
3
for 30 min. An organic layer
General procedure
4
,
The chemicals and solvents were used as received from commercial
suppliers (Merck, Warsaw, Poland; Sigma-Aldrich, Poznan, Poland;).
filtered out and the solvent was evaporated to obtain a yellow-
ish solid. α-Amino aldehydes derived from D-amino or L-amino
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SYNTHESIS OF RIGID TRYPTOPHAN MIMETICS
Figure 5. Schematic presentation of the NOE effect (yellow arrows) in the molecule adopting the β-turn structure stabilized by a hydrogen bond (blue
dotted line) and a ROESY spectrum of the compound 6a.
acids with Z protection of amino group were prepared in good
or excellent yields via the Fehrentz–Castro [36] procedure and
used immediately without purification to avoid racemization.
Homologation of 3-(tert-butyloxycarbonylamino)-1-diazo-4-indolebutan-
3-one to Boc-β -homo-tryptophan
3
N-protected α-aminodiazoketone was dissolved in ethyl acetate
(6ml per 0,1g of crude α-aminodiazoketone). Silver benzoate (4%
mol) and silica gel (1g per 0.1g α-aminodiazoketone) were added,
and the mixture (under the exclusion of light) was stirred on the
rotary evaporator for 8 h at 45 °C (the reaction was monitored by
TLC). The silica gel was filtered off and washed with AcOEt. The
3
Preparation of boc-β -homo-tryptophan
Synthesis of 3-(tert-butyloxycarbonylamino)-1-diazo-4-indolebutan-
3
-one
3
ethyl acetate was evaporated to yield Boc-β -homo-tryptophan
2
0
yellow solid (yield 76%). [α]
= 17,8min; Rf (CHCl –MeOH 9 : 1) = 0.28; H NMR (CDCl
00 MHz) δ (ppm) 1.40 (s, 9H, CH ); 2.49–2.62 (m, 2H, CH
.93–3.05 (m, 2H, CH ); 5.08 (m, 1H, CH); 7.01–7.32 (m, 4H, Ar);
.64 (d, J = 7.75 Hz, 1H, Ar); 8.02 (bs, 1H, NHind); ESI m/z: 218.90
D
= À14.0 (c 1, CH
3
OH); HPLC (grad. 1)
Triethylamine (0.830 g, 0.741ml, 8.21 mmol) and then ethyl
chloroformate (0.895 g, 0.792 ml, 8.21 mmol) were added to a solu-
tion of Boc-tryptophan (2.50 g, 8.21 mmol) in anhydrous tetrahydro-
furan (40ml) through a rubber septum under argon at 0 °C. After
1
t
R
3
3
,
2
);
2
2
7
3
2
1
5 min, a white precipitate of triethylammonium chloride appears,
+
+
+
[
M–Boc] , 340.85 [M + Na] , 356.85 [M + K] ;
the stirring was stopped, the septum was replaced with a funnel
and a freshly prepared diazomethane ethereal solution was added.
The mixture was slowly stirred for 3 h (the reaction was monitored
by TLC). The excess diazomethane was destroyed by an addition of
a few drops of acetic acid and a saturated aqueous solution sodium
bicarbonate (10 ml) was added carefully. The aqueous layer was
separated and the organic layer was washed with a saturated aque-
ous sodium chloride (3× 30 ml). The organic layer was dried over
MgSO4, filtered off and the solvent was evaporated. The crude
α-aminodiazoketone was used directly in the next step and
solvents were used as received from commercial suppliers.
General procedure for Pictet-Spengler reaction
3
3
3
0.50 mmol of β -hTrpOCH
was dissolved in 10 ml CH
aldehyde in 10 ml CH Cl
and mixture was cooled to À40 °C. 5 eq
(0.192 ml) of TFA in 1.5mL CH Cl was added in three portions.
The reaction mixtures were stirred for 5 h at -40 °C and then at RT
overnight. The mixtures were diluted with CH Cl , and a saturated
solution of NaHCO was added to neutralize TFA. Organic layers
were separated, extracted with saturated solution of NaHCO , after
3
or β -hTrpAlaOCH
3 3
or β -hTrpAlaOCH
2
Cl and added to 0.60mmol of amino
2
2
2
2
2
2
2
3
3
J. Pept. Sci. 2015; 21: 893–904
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SLUPSKA ET AL.
then washed with brine and dried over MgSO , filtrated off and the
solvent was evaporated to crude yellowish solids or oils. The ratios
(H-3, H-4a, H-3’a and H-3’b), H-3’a (H-1, H-3, H-4a, H-3b), H-3’a (H-1,
H-3, H-4a, H-3b), H-1’(H-1, H-3, NHZ, CH(CH )CH CH , CH(CH )
4
3
2
3
3
of the cis/trans isomers in the crude mixtures were determined by
HNMR (based on the integration of separated peaks of methyl
ester groups). Crude mixtures were purified and cis/trans isomers
CH CH , CH ), CH(CH )CH CH (H-1, H-1’, CH(CH )CH CH , CH ,
2 3 3 3 2 3 3 2 3 3
1
+
NH), NHZ (H-1’); NH (CH(CH )CH CH ); ESI m/z: 464 [M+ H] ; exact
3 2 3
+
mass calculated for C H N O [M + H] : 464.2544, found: 464,2551.
27 33 3 4
were separated by flash chromatography (CHCl /AcOEt) or by
3
semi-preparative HPLC to obtain 10–20 mg of pure isomers cis
and trans.
2 3
Tcc(Z-L-Phe)CH COOCH 3c and 4c
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 47/53.
2 3
Tcc(Z-L-Ala)CH COOCH 3a and 4a
2
0
cis 3c: Yield: 23%; yellowish foam; [α] = À51.1 (c 1, CH OH); t
D
3
1
R
The ratio of cis/trans isomers determined before purification by 1H
(grad. 1) = 16.20 min; R (CHCl3 – Acetone 3 : 2) = 0.83; H NMR
f
NMR (200 MHz) was 60/40.
(700 MHz, CDCl ) δ 2.90 (m, 2H, H-4a and H-4b); 3.02 (m, 2H, CH Ph);
3
2
2
0
cis 3a: Yield: 28%; yellowish foam; [α]
grad. 1) = 15.81 min; t (grad. 2)= 11.07 min; R
:2) = 0.62; H NMR (700 MHz, CDCl ) δ 1.03 (d, J = 6.8 Hz, 3H, CH
.51 (m, 1H, H-4b); 2.65 (dd, J =17.6 Hz, J = 6.2Hz, 2H, H-3’a and
D
= À14.0 (c 1, CH
(CHCl – Acetone
);
3
OH); t
R
3.14 (d, J = 13.7 Hz, 2H, H-3’a and H-3’b); 3.58 (m, 1H, H-3); 3.73 (s, 3H,
OCH ); 4.76 (s, 1H, H-1’); 4.88 (q, J = 12.5 Hz, 2H, CH Ph ); 5.15 (s, 1H,
H-1); 6.15 (s, 1H, NHZ); 6.91–7.43 (m, 14H, Ar); 8.78 (s, 1H, NHind);
NMR (700 MHz, CDCl ) δ 24.5 (C-4), 35.7 (C-3’), 36.1 (CH Ph), 52.9
(C-3), 53.3 (OCH ), 54.5 (C-1’), 59.1 (C-1), 67.2 (CH Ph ),
111.7–129.0 (Ar); ROESY (700 MHz, CDCl ) H-1 (H-1’, H-3’a,
H-3’b, CH CH(CH ); H-3 (H-4a, H-4b, H-3’a, H-3’b), H-4a (H-3,
(
3
2
R
f
3
3
2
Z
1
13
3
3
C
3
2
H-3’b); 2.81 (m, 1H, H-4a); 3.34 (dq, J = 8.8Hz, J = 4.7Hz, 1H, H-3);
.72 (s, 3H, OCH ); 4.33 (bs, 1H, H-1’); 4.39 (s, 1H, H-1); 5.13 (q,
J = 12.3 Hz, 2H, CH Ph); 5.49 (d, J = 8.3Hz, 1H, NHZ); 7.05-7.52 (m,
0H, Ar, NH); 8.56 (s, 1H, NHind); C NMR (700 MHz, CDCl
CH ); 27.9 (C-4); 40.4 (C-3’); 49.6 (C-1’); 50.5 (C-3); 51.6 (OCH
C-1); 66.9 (CH Ph); 94.9–127.9 (Ar); ROESY (700 MHz, CDCl3) H-1
H-3, NHZ, CH ); H-3 (H-1, H-4a, H-3’a and H-3’b), H-4a (H-3, H-4b,
3
2
Z
3
3
3
2
2
3 2
)
13
1
3
) δ 14.4
); 56.4
H-4b, H-3’a and H-3’b), H-4b (H-3, H-4a, H-3’a and H-3’b), H-3’a
(H-1, H-3, H-4a, H-3b), H-3’a (H-1, H-3, H-4a, H-3b), H-1’(H-1, H-3,
(
(
(
3
3
2
NHZ, CH
H-1’, CH
); ESI m/z: 498 [M + H] , 520 [M + Na] ; exact mass calculated
2
CH(CH
3
)
2
, CH
2
CH(CH
3
)
2
, CH
3
, NH), CH
2
CH(CH
3
)
2
(H-1,
3
2
CH(CH
3
)
2
, CH
3
, NH), NHZ (H-1’); NH (H-1’, CH
2
CH(CH )
3
+
+
H-3’a and H-3’b), H-4b (H-4a, H-3’a and H-3’b), H-3’a and H-3’b (H-
2
+
3
, H-4a, H-3b), H-1’(CH
3
), CH
3
(H-1’, NHZ), NHZ (H-1, CH
3
); ESI m/z:
for C30
trans 4c: Yield: 37%; yellowish foam; [α]
(grad. 1) = 17.17 min; R (CHCl – Acetone 3 : 2) = 0.72; H NMR
(700 MHz, CDCl ) δ 2.83 (m, 1H, H-3’b); 2.99 (m, 2H, H-4b and
CH Ph); 3.11 (m, 1H, H-3’a); 3.22 (m, 2H, H-4b and CH Ph); 3.63 (s,
3H, OCH ); 4.32 (s, 1H, H-3); 4.47 (s, 1H, H-1); 4.82 (d, J = 12.4Hz,
1H, H-1’); 4.94 (dd, J = 31.9 Hz, J = 11.0 Hz, 2H, CH Ph ); 6.16 (s, 1H,
31 3 4
H N O [M + H] : 498.2387, found: 498.2409.
+
+
20
422 [M + H] , 444 [M+ Na] ; exact mass calculated for C24
H N O
27 3 4
D 3 R
= +69.3 (c 1, CH OH); t
+
1
[
(
3
2
M+ H] : 422. 2074, found: 422.2090.
f
3
2
D
0
trans 4a: Yield: 19%; yellowish foam; [α]
= +79.3 (c 1, CH
(CHCl
) δ 1.32 (d, J = 6.5 Hz, 3H, CH
.51 (m, 1H, H-4b); 2.64 (dd, J =15.9 Hz, J = 9.8Hz, 2H, H-3’a and
3
OH); t
R
3
grad. 1) = 15.89 min; t
R
(grad. 2)= 11.15 min; R
f
3
– Acetone
);
2
2
1
:2) = 0.40; H NMR (700 MHz, CDCl
3
3
3
2
Z
1
3
H-3’b); 3.02 (d, J = 4.9 Hz, 1H, H-4a); 3.69 (s, 3H, OCH ); 3.79 (m, 1H,
H-3); 4.10 (bs, 1H, H-1’); 4.33 (s, 1H, H-1); 4.97 (s, 2H, CH Ph); 5.60
NHZ); 6.85–7.56 (m, 14H, Ar); 9.54 (s, 1H, NHind); C NMR
(700 MHz, CDCl ) δ 24.5 (C-4), 35.2 (C-3’), 37.5 (CH Ph), 48.4 (C-3),
3
2
3
2
(
d, J = 8.2Hz, 1H, NHZ); 7.06–7.50 (m, 10H, Ar, NH); 8.60 (s, 1H, NHind);
53.25 (OCH ), 54.2 (C-1), 55.4 (C-1’), 66.9 (CH Ph ), 111.8–128.9
(Ar); ROESY (700 MHz, CDCl ) H-1 (H-4b and CH Ph, H-4a and
3 2
3
2
Z
1
3
C NMR (700 MHz, CDCl ) δ 17.8 (CH ); 26.6 (C-4); 37.3 (C-3’); 47.6
3
3
(
(
C-3); 48.6 (C-1’); 51.5 (OCH ); 53.4 (C-1); 66.2 (CH Ph), 95.4-128.2
CH Ph , NHZ); H-3 (H-4b and CH Ph, H-4b and CH Ph, H-3’b,
2 Phe 2 2
H-3’a), H-4a and CH Ph (H-1, H-3, H-4b and CH Ph), H-4b and CH Ph
2 2 2
3
2
Ar); ROESY (700 MHz, CDCl ) H-1 (NHZ, CH ); H-3 (H-4a, H-4b,
3
3
H-3’a and H-3’b), H-4a (H-3, H-4b, H-3’a and H-3’b), H-4b (H-3,
H-4a, H-3’a and H-3’b), H-3’a and H-3’b (H-3, H-4a, H-3b), H-1’(CH3,
NHZ), CH (H-1, H-1’, NHZ), NHZ (H-1, H-1’, CH ); ESI m/z: 422 [M
(H-1, H-3, H-4a and CH Ph), H-3’a (H-3, H-3’b), H-3’b (H-3, H-3’a), H-1’
2
(H-4a and CH Ph, H-4b and CH Ph), NHZ (H-1); ESI-MS m/z: 498 [M
2
2
+
+
+
+ H] , 520 [M + Na] exact mass calculated for C H N O [M+ H] :
3
3
30 31 3 4
+
+
+
+
H] , 444 [M + Na] ; exact mass calculated for C H N O [M
H] : 422. 2074, found: 422.2086.
498.2387, found: 498.2410.
24 27 3 4
+
Tcc(Z-L-Val)CH COOCH 4d
2
3
2 3
Tcc(Z-L-Ile)CH COOCH 4b
The ratio of cis/trans isomers determined before purification by 1H
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 0/100.
2
0
NMR (200 MHz) was 0/100
trans 4d: Yield: 35%; yellowish foam; [α]
(grad. 1) = 16.52 min; R (CHCl – Acetone 3 : 2) = 0.63; H NMR
(700 MHz, CDCl ) δ 1.06 (t, J = 7.2 Hz, 6H, CH ); 1.85 (ddd, J = 15.8 Hz,
J = 10.0 Hz, J = 4.6 Hz, 1H, CH(CH ); 2.42 (dd, J = 16.1 Hz, J = 4.0 Hz,
1H, H-4b); 2.52 (m, 1H, H-3’b); 2.67 (dt, J = 18.7 Hz, J = 9.3 Hz, 1H,
H-4a); 3.05 (m, 1H, H-3’a); 3.69 (s, 3H, OCH ); 3.81 (dd, J = 9.9 Hz,
J = 2.4 Hz, 1H, H-3); 3.85 (dt, J = 9.7 Hz, J = 2.4 Hz, 1H, H-1’); 4.39
(s, 1H, H-1); 5.11 (m, 2H, CH Ph ); 5.43 (d, J = 9.9 Hz, 1H, NHZ);
6.86–7.47 (m, 9H, Ar); 8.30 (s, 1H, NHind); C NMR (700 MHz,
CDCl ) δ 19.4 (CH ), 26.7 (C-4), 30.1 (CH(CH ), 36.9 (C-3’),
48.1 (C-3), 48.9 (C-1), 52.7 (OCH ), 58.7 (C-1’), 66.9 (CH Ph ),
111.8–128.9 (Ar); ROESY (700 MHz, CDCl ) H-1 (H-1’, H-3’a, CH
(CH , CH , NHZ); H-3 (H-3’a, H-3’b, H-4a, H-4b), H-4a (H-3,
H-4b); H-4b (H-3, H-4b); H-3’a (H-1, H-3, H-3’b); H-3’b (H-3, H-3’a);
H-1’ (H-1, CH(CH , CH , NHZ, NHind); CH(CH (H-1, H-1’, CH ),
D 3 R
= +22.6 (c 1, CH OH); t
2
0
1
trans 4b: Yield: 37%; yellowish foam; [α]
grad. 1) = 17.17 min; R (CHCl – Acetone 3 : 2) = 0.72; H NMR
700 MHz, CDCl ) δ 0.99 (m, 6H, CH ), 1.22 (m, 2H, CH(CH )CH CH ),
.98 (m, 1H, CH(CH )CH CH ); 2.78 (dd, J = 17.4 Hz, J = 4.6 Hz, 1H, H-
’b); 2.92 (dd, J = 16.6 Hz, J = 6.6 Hz, 1H, H-4b); 3.09 (m, 1H, H-3’a);
.24 (dt, J =24.5 Hz, J = 12.3Hz, 1H, H-4a); 3.69 (s, 3H, OCH ); 4.21
D
= +69.3 (c 1, CH
3
OH); t
R
f
3
1
(
(
f
3
3
3
3
3
3
2
3
3 2
)
1
3
3
3
2
3
3
3
(
dt, J = 19.0 Hz, J = 9.4 Hz, 1H, H-1’); 4.30 (bs, 1H, H-3); 4.91 (d,
J = 6.5 Hz, 1H, H-1); 5.02 (s, 2H, CH Ph); 6.35 (d, J = 9.4Hz, 1H, NHZ);
.99–7.54 (m, 10H, Ar, NH); 8.78 (s, 1H, NHind); C NMR (700MHz,
CDCl ) δ 11.1 (CH ); 17.1 (CH ); 23.6 (CH(CH )CH CH ); 24.1 (C-4);
4.4 (C-3’); 34.7 (CH(CH )CH CH ); 48.6 (C-3); 52.7(C-1’); 53.4
OCH ); 56.6 (C-1’); 67.9 (CH Ph), 111.8–128.9 (Ar); ROESY
700 MHz, CDCl3) H-1 (H-1’, H-3’a, H-3’b, CH(CH )CH CH ); H-3
H-4a, H-4b, H-3’a, H-3’b), H-4a (H-3, H-4b, H-3’a and H-3’b), H-4b
2
Z
1
3
2
13
6
3
3
3 2
)
3
3
3
3
2
3
3
2
Z
3
3
2
3
3
(
(
(
3
2
3
)
2
3
3
2
3
)
3 2
3
)
3 2
3
wileyonlinelibrary.com/journal/jpepsci
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
J. Pept. Sci. 2015; 21: 893–904

SYNTHESIS OF RIGID TRYPTOPHAN MIMETICS
CH (H-1, H-1’, CH(CH ) ); NHZ (H-1’); NH (H-1’, Ar); ESI m/z: 450
CDCl ) H-1 (H-3, CH Phe); H-3 (H-1, H-4b, H-3’a, H-3’b), H-4a (H-4b,
3 2
3
3 2
ind
+
+
[
M + H] ; exact mass calculated for C H N O [M + H] : 450.2387,
H-3’a), H-4b (H-3, H-4a), H-3’a (H-3, H-4a, H-3’b), H-3’b (H-3, H-3’a),
2
6 31 3 4
+
found: 450.2392.
H-1’ (CH Ph), CH Ph (H-1, H-1’); ESI m/z: 498 [M + H] , 520 [M
+
2
2
+
+
Na] exact mass calculated for C H N O [M+ H] : 498.2387
30 31 3 4
found: 498.2407.
Tcc(Z-D-Ala)CH COOCH 3e
2
3
The ratio of cis/trans isomers determined before purification by 1H
2 3
Tcc(Z-D-Val)CH COOCH 3h
NMR (200 MHz) was 100/0.
cis 3e: Yield: 39%; yellowish foam; [α] D = +16.7 (c 1, CH OH); t
20
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 100/0.
cis 3h: Yield: 48%; yellowish foam; [α] = +25.6 (c 1, CH OH); t
3
1
R
(
grad. 1) = 15.84 min; R (CHCl3 – Acetone 3 : 2)= 0.65; H NMR
f
2
0
(
700 MHz, CDCl ) δ 1.60 (d, J =6.2 Hz, 3H, CH ); 3.04 (dd,
3
3
D
3
1
R
J = 15.9 Hz, J = 4.0 Hz, 1H, H-4b); 3.11 (m, 1H, H-3’b); 3.14 (m, 1H,
H-4a); 3.41 (dd, J = 17.6 Hz, J = 7.9Hz, 1H, H-3’a); 3.78 (s, 3H, OCH3);
(grad. 1)= 16.15 min; R (CHCl3 – Acetone 3 : 2) = 0.81; H NMR
f
(700 MHz, CDCl ) δ 1.11 (d, J = 6.3 Hz, 3H, CH ); 1.22 (d, J = 6.6 Hz,
3
3
3
.79 (bs, 1H, H-3); 4.76 (bs, 1H, H-1’); 4.89 (s, 1H, H-1); 4.95 (d,
J = 12.6 Hz, 2H, CH Ph); 5.35 (s, 1H, NHZ); 6.84-7.67 (m, 10H, Ar,
3
NH); 9.23 (s, 1H, NHind); C NMR (700MHz, CDCl );
3H, CH
3
); 2.19 (m, 1H, CH(CH
3
)
2
); 2.95 (dd, J = 18.0Hz, J = 2.3 Hz,
2
1H, H-3’b); 3.03 (dd, J = 15.8 Hz, J = 3.9Hz, 1H, H-4b); 3.21 (m, 1H,
H-4a); 3.49 (dd, J = 18.1 Hz, J = 10.4 Hz, 1H, H-3’a); 3.76 (s, 1H, H-3);
13
3
) δ 16.7 (CH
); 54.1 (C-3); 60.1 (C-1);
Ph); 111.9–128.4 (Ar); ROESY (700MHz, CDCl ) H-1 (H-3,
); H-3 (H-1, H-4a, H-3’a, H-3’b), H-4a (H-3, H-4b, H-3’a, H-3’b), H-
b (H-4a, H-3’a, H-3’b), H-3’a (H-3, H-4a, H-3b), H-3’b (H-3, H-4a, H-
2
6
CH
4
3
4.3 (C-4); 35.7 (C-3’); 46.6 (C-1’); 52.7 (OCH
7.8 (CH
3
3.81 (s, 3H, OCH
2H, CH Ph); 4.96 (s, 1H, H-1); 5.09 (s, 1H, NHZ); 6.88–7.51 (m, 9H,
Ar); 8.18 (bd, J = 37.3 Hz, 1H, NHind); C NMR (700 MHz, CDCl
18.8 (CH ), 24.5 (C-4), 29.0 (CH(CH ), 35.2 (C-3’), 53.2 (OCH ), 54.5
(C-3), 56.6 (C-1’), 57.2 (C-1), 67.5 (CH Ph), 111.9–128.2 (Ar); ROESY
(700 MHz, CDCl ) H-1 (H-3, H-1’, CH(CH ); H-3 (H-1, H-4b, H-3’a,
H-3’b), H-4a (H-4b), H-4b (H-3, H-4a, H-3’b), H-3’a (H-3, H-3’b),
H-3’b (H-3, H-4b, H-3’a), H-1’ (H-1, CH(CH , CH ), CH(CH (H-1,
); ESI m/z: 450 [M+ H] , exact mass calculated for
3
); 4.21 (dd, J = 10.3 Hz, J = 8.0 Hz, 1H, H-1’); 4.94 (s,
2
3
2
13
3
3
) δ
3
)
3 2
3
+
+
b), H-1’(CH
3
), CH
3
(H-1, H-1’); ESI m/z: 422 [M + H] , 444 [M + Na] ;
2
+
exact mass calculated for C24
H N O
27 3 4
[M + H] : 422.2074 found:
3
3 2
)
422.2079.
)
3 2
3
3 2
)
+
H-1’, CH
3
2 3
Tcc(Z-D-Leu)CH COOCH 3f
+
26 31 3 4
C H N O [M+ H] : 450.2387, found: 450.2385.
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 100/0.
Tcc(Z-L-Ala)CH -Ala-COOCH 5a and 6a
2
0
2
3
cis 3f: Yield: 62%; yellowish foam; [α]
grad. 1) = 17.29 min; R (CHCl – Acetone 3 : 2)= 0.78; H NMR
700 MHz, CDCl ) δ 0.95 (dd, J = 13.6 Hz, J = 6.2 Hz, 6H, CH ); 1.48
m, 1H, CH CH(CH ) ); 1.74 (m, 1H, CH CH(CH ) ); 1.92 (m, 1H,
D 3 R
= +18.7 (c 1, CH OH); t
1
(
f
3
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 35/65.
(
3
3
2
0
(
cis 5a: Yield: 17%; yellowish foam; [α] = À9.9 (c 1, CH OH); t
2
3 2
2
3 2
D
3
1
R
CH CH(CH ) ); 2.89 (d, J = 5.3Hz, 2H, H-4a and H-4b); 2.92 (d,
(grad. 1)= 15.64 min; R (CHCl3 – Acetone 3 : 2) = 0.51; H NMR
2
3 2
f
J = 5.0 Hz, 1H, H-3’b); 3.15 (m, 1H, H-3’a); 3.64 (s, 1H, H-3); 3.75 (s,
(700 MHz, CDCl ) δ 1.34 (q, J = 6.1 Hz, 3H, CH3pept); 1.54 (d,
3
3
H, OCH ); 4.56 (m, 1H, H-1’); 4.78 (s, 1H, H-1); 4.91 (d, J = 4.2Hz,
J = 6.3 Hz, 3H, CH ); 2.41 (m, 1H, H-3’b); 2.53 (m, 3H, H-4b and H-
3
3
2
H, CH Ph); 6.72 (d, J = 8.7Hz, 1H, NHZ); 6.94–7.40 (m, 9H, Ar); 9.23
3’a); 3.16 (dd, J = 18.0Hz, J = 5.6Hz, 1H, H-4a); 3.58 (s, 1H, H-3);
2
1
3
(s, 1H, NHind); C NMR (700MHz, CDCl ) δ 21.9 (CH ), 24.4 (C-4),
3.67 (s, 3H, OCH ); 4.42 (m, 1H, NHZ); 5.52 (m, 1H, CHpept); 4.66 (s,
3
3
3
2
4.9 (CH CH(CH ) ), 35.8 (C-3’), 39.3 (CH CH(CH ) ), 49.10 (C-1’),
1H, H-1’); 4.90 (d, J = 9.5Hz, 1H, H-1); 5.02 (dd, J = 25.7 Hz,
2
3 2
2
3 2
5
1.7 (OCH ), 54.4 (C-3), 60.6 (C-1), 67.6 (CH Ph), 112.6–129.0 (Ar);
J = 11.9 Hz, 2H, CH Ph); 6.72 (s, 1H, NHpept); 7.00–7.51 (m, 9H, Ar);
3
2
2
1
3
ROESY (700 MHz, CDCl ) H-1 (H-3, H-1’, CH CH(CH ) , CH CH(CH )
8.85 (s, 1H, NHind); C NMR (700MHz, CDCl ) δ 18.4 (CH3pept), 20.2
3
2
3 2
2
3
3
2)
’a, H-3’b), H-3’a (H-3, H-4a and H-3b), H-3’b (H-3, H-4a and H-3b),
H-1’(H-1, CH CH(CH ) , CH CH(CH ) , NHZ), CH CH(CH ) (H-1, H-1’,
; H-3 (H-1, H-4a and H-4b, H-3’a, H-3’b), H-4a and H-4b (H-3, H-
(CH ), 23.9 (C-4), 38.2 (C-3’), 46.3 (C-1’), 52.5 (C-3), 52.6 (OCH ), 53.7
3
3
3
(C-1’), 54.3 (CHpept), 67.1 (CH Ph), 111.3–128.6 (Ar); ROESY
2
(700 MHz, CDCl ) H-1 (H-3, CH ); H-3 (H-1, H-3’a and H-4b, H-3’b),
2
3 2
2
3 2
2
3 2
3
3
NHZ, CH CH(CH ) , CH ), NHZ (H-1’, CH CH(CH ) , CH CH(CH ) ,
H-4a (H-4b and H-3’a, H-3’b), H-4b and H-3’a (H-3, H-4a, H-3’b), H-
3’b (H-3, H-3’a and H-4b), H-1’ (H-3, CH , NHZ), CH (CH3pept ),
2
3 2
3
2
3 2
2
3 2
+
CH ); ESI m/z: 464 [M + H] , exact mass calculated for C H N O
3
27 33
3
4
3
pept
+
[M + H] : 464.2544 found: 464.2551.
CH (H-1’, NHZ), CH
(NHpept), NHZ (H-1’, CH ), NHpept(CH3pept);
3
3pept 3
+
ESI m/z: 493 [M+ H] ; exact mass calculated for C27
H N O
32 4 5
[M
+
+
H] : 493.2445 found: 493.2468.
2 3
Tcc(Z-D-Phe)CH COOCH 3g
2
0
trans 6a: Yield: 27%; yellowish foam; [α]
D
= +18.1 (c 1, CH
3
OH); t
R
1
The ratio of cis/trans isomers determined before purification by 1H
(grad. 1)= 15.10 min; R
(700 MHz, CDCl ) δ 1.36 (q, J = 6.5 Hz, 3H, CH3pept); 1.42 (d,
J = 6.0 Hz, 3H, CH ); 2.59 (m, 1H, H-4b); 2.63 (d, J = 7.1Hz, 1H, H-4a);
2.78 (m, 2H, H-3’a and H-3’b); 3.32 (bs, 1H, H-3); 3.56 (s, 3H, OCH );
4.52 (dd, J = 7.5 Hz, 2H, CHpept and H-1’); 4.57 (m, 1H, H-1); 5.10 (td,
J = 25.6 Hz, J = 7.5 Hz, 2H, CH Ph); 6.27 (s, 1H, NHZ); 7.07–7.49 (m,
9H, Ar); 8.44 (s, 1H, NHpept); 8.85 (s, 1H, NHind); C NMR (700MHz,
CDCl ) δ 15.1 (CH3pept), 17.9 (CH ), 27.9 (C-4), 41.5 (C-3’), 48.4 (C-1),
48.8 (C-1’), 52.2 (C-3), 52.5 (OCH ), 57.7 (CHpept), 67.2 (CH Ph),
111.2–130.9 (Ar); ROESY (700MHz, CDCl ) H-1 (NHZ, CH ); H-3
f 3
(CHCl – Acetone 3 : 2) = 0.71; H NMR
NMR (200 MHz) was 100/0.
3
2
0
cis 3g: Yield: 47%; yellowish foam; [α]
grad. 1) = 16.51 min; R (CHCl – Acetone 3 : 2)= 0.83; H NMR
700 MHz, CDCl ) δ 2.94 (dd, J = 17.9Hz, J = 3.5 Hz, 1H, H-3’b), 2.99
dd, J = 16.6Hz, J =4.2 Hz, 1H,H-4b), 3.10 (m, 1H, H-4a); 3.14 (dd,
J = 14.1Hz, J =7.3 Hz, 1H, CH Ph); 3.28 (dd, J = 13.9 Hz, J = 8.8Hz,
H, CH Ph); 3.39 (dd, J = 18.0Hz, J = 9.7Hz, 1H, H-3’a); 3.71 (m, 1H,
H-3); 3.84 (s, 3H, OCH ); 4.78 (s, 1H, H-1); 4.85 (m, 1H, H-1’); 4.89
dt, J = 20.8 Hz, J = 10.4 Hz, 2H, CH Ph ); 5.09 (s, 1H, NHZ);
D
= +66.2 (c 1, CH
3
OH); t
R
3
1
(
f
3
3
(
3
(
2
13
2
1
2
3
3
3
3
2
(
2
Z
3
3
3
1
6
.93–7.48 (m, 14H, Ar); 9.11 (s, 1H, NHind); C NMR (700 MHz, CDCl
Ph), 52.2 (C-1’), 53.7 (OCH ), 53.9
), 111.9–129.0 (Ar); ROESY (700 MHz,
3
)
(H-4a, H-1’, H-3’a and H-3’b), H-4a (H-3, H-3’a and H-3’b), H-4b
(H-3, H-3’a and H-3’b), H-3’a and H-3’b (H-3, H-4a, H-4b), H-1’ (H-3),
δ 24.7 (C-4), 35.5 (C-3’), 36.7 (CH
C-3), 58.1 (C-1), 66.9 (CH Ph
2
3
(
2
Z
CHpept (CH3pept), CH
3
(H-1), CH3pept (NHpept), NHZ (H-1), NHpept
J. Pept. Sci. 2015; 21: 893–904
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/jpepsci

SLUPSKA ET AL.
+
+
+
(
CH3pept); ESI m/z: 493 [M + H] ; exact mass calculated for
+ Na] ; exact mass calculated for C H N O [M + H] : 569.2758
33
36 4 5
+
C H N O [M+ H] : 493.2445 found: 493.2467.
found: 569.2767.
3
Tcc(Z-L-Val)CH -Ala-COOCH 6d
27 32 4 5
Tcc(Z-L-Ile)CH -Ala-COOCH 6b
2
3
The ratio of cis/trans isomers determined before purification by
H NMR (200 MHz) was 0/100.
trans 6b: Yield: 37%; yellowish foam; [α] D = +8.4 (c 1, CH OH); t
2
1
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 0/100.
trans 6d: Yield: 35%; yellowish foam; [α]
grad. 1) = 16.43 min; R (CHCl
700 MHz, CDCl ) δ 1.09 (t, J = 6.6 Hz, 3H, CH
H, CH ); 1.38 (d, J = 7.1 Hz, CH ); 1.95 (m, 1H, CH(CH ) ); 2.52
d, J = 8.1 Hz, 1H, H-4b); 2.60 (m, 2H, H-3’a and H-3’b); 2.75 (m, 1H,
H-4a); 3.44 (bs, 1H, H-3); 3.67 (s, 3H, OCH ); 3.87 (m, 1H, H-1); 4.50
s, 1H, H-1’); 4.60 (dd, J = 14.3 Hz, J = 7.1 Hz, 1H, CHpept); 4.89 (dd,
J = 55.0Hz, J = 12.5 Hz, 2H, CH Ph); 5.11 (s, 1H, NHZ); 6.88–7.45 (m,
20
3
R
1
(
(
1
1
grad. 1) = 17.97 min; R (CHCl3 – Acetone 3 : 2) = 0.36; H NMR
20
f
D 3 R
= +3.9 (c 1, CH OH); t
– Acetone 3 : 2) = 0.38; H NMR
); 1.14 (d, J = 6.6Hz,
700 MHz, CDCl ) δ 0.96 (m, 6H, CH ); 1.02 (d, J = 6.7Hz, 3H, CH3pept);
1
3
3
(
f
3
.24 (m, 1H, CH(CH )CH CH ); 1.66 (m, 2H, CH(CH )CH CH ); 2.37 (m,
3 2 3 3 2 3
(
3
3
H, H-4b); 2.42 (m, 2H, H-3’a and H-3’b); 2.94 (dd, J = 15.2 Hz,
J = 4.2 Hz, 1H, H-4a); 3.66 (dd, J = 9.6 Hz, J = 4.5 Hz, 1H, H-3);
.70 (s, 3H, OCH ); 3.90 (d, J = 9.9 Hz, J = 2.2 Hz, 1H, H-1’); 4.36
s, 1H, CHpept); 4.71 (m, 1H, H-1); 4.85 (dd, J = 66.7 Hz,
J = 12.7 Hz, 2H, CH Ph); 5.57 (d, J = 5.7 Hz, 1H, NHZ); 6.90 (d,
3
3
3pept
3 2
(
3
(
3
3
(
2
2
J = 7.5 Hz, 1H, NHpept); 7.02–7.43 (m, 9H, Ar); 8.42 (s, 1H, NHind);
13
9
H, Ar); 7.48 (s, 1H, NHpept); 8.35 (s, 1H, NHind); C NMR (700 MHz,
1
3
C NMR (700 MHz, CDCl
CH )CH CH ), 25.8 (CH(CH
0.2 (CHpept), 50.6 (C-1), 52.6 (OCH
11.4–128.5 (Ar); ROESY (700 MHz, CDCl
3
) δ 16.1 (CH
)CH CH
), 58.1 (C-1’), 69.8 (CH
) H-1 (CH3pept, NHZ);
3
), 21.8 (CH3pept), 24.9 (CH
), 28.2 (C-4), 40.5 (C-3’),
Ph),
CDCl ) δ 18.30 (CH ), 20.0 (CH ), 27.5 (C-4), 29.7 (CH(CH ) ),
3
3pept
3
3 2
(
5
1
3
2
3
3
2
3
4
2.1 (C-3’), 47.9 (CHpept), 51.1 (C-3), 52.4 (OCH ), 54.2 (C-1’), 57.9
C-1), 67.7 (CH Ph), 111.4-128.4 (Ar); ROESY (700 MHz, CDCl ) H-1
H-1’, CH(CH ) , CH ), H-3 (H-4a , H-3’a and H-3’b), H-4a (H-3, H-4b,
H-3’a and H-3’b), H-4b (H-4a, H-3’a and H-3’b), H-3’a and H-3’b
H-3, H-4a, H-4b), H-1’ (H-1, CH(CH ) , CH ); CH(CH ) (H-1, H-1’,
CH , NHZ), CH (H-1, H-1’, CH(CH ) ), CHpept(CH
CHpept), NHZ (H-1’, CH(CH ) ); ESI m/z: 521 [M + H] , 543 [M + Na] ;
exact mass calculated for C H N O [M+ H] : 521.2772 found:
3
3
2
(
2
3
3
(
3 2 3
H-3 (H-4a, H-4b, H-3’a and H-3’b), H-4a (H-3, H-4b, H-3’a and
H-3’b), H-4b (H-3, H-4a, H-3’a and H-3’b), H-3’a and H-3’b (H-3,
(
3 2 3 3 2
H-4a, H-4b, CHpept), H-1’ (CH
NHZ), CHpept(CH3pept), CH(CH
CH , NHZ), NHpept (CHpept), NHZ (H-1, H-1’, CH(CH
ESI m/z: 535 [M + H] , 557 [M + Na] ; exact mass calculated for
3
, CH(CH
3
)CH
2
CH
3
, CH(CH
3
)CH
2
CH
3
,
, NHpept), NH
pept
3
3
3 2
3pept
)CH CH
2
3
(H-1’, CH(CH
3
)CH
2
CH
3
,
+
+
3
(
3 2
)CH
2
CH
3
);
+
3
3
2
9 36 4 5
+
+
5
21.2781.
+
30 38 4 5
C H N O [M + H] : 535.2915, found: 535.2941.
Tcc(Z-D-Ala)CH -Ala-COOCH 5e
2
3
Tcc(Z-L-Phe)CH COOCH 5c and 6c
2
3
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 100/0.
cis 5e: Yield: 63%; yellowish foam; [α] = +15.6 (c 1, CH OH); t
(grad. 1) = 15.63 min; R (CHCl3 – Acetone 3 : 2) = 0.50; H NMR
f
The ratio of cis/trans isomers determined before purification by 1H
2
0
D
3
R
NMR (200 MHz) was 26/73.
1
2
0
cis 5c: Yield: 39%; yellowish foam; [α] = À12.9 (c 1, CH OH); t
D
3
1
R
(700 MHz, CDCl ) δ 1.41 (m, 6H, CH
and CH ); 2.65 (d,
3
3pept 3
(
grad. 1) = 17.19 min; R (CHCl3 – Acetone 3 : 2) = 0.55; H NMR
f
J = 11.8Hz, 1H, H-4b); 2.74 (m, 3H, H-3’a and H-3’b); 2.85 (d,
J = 12.9Hz, 1H, H-4a); 3.50 (m, 1H, H-3); 3.73 (s, 3H, OCH ); 4.43 (bs,
(
700 MHz, CDCl ) δ 0.98 (m, 3H, CH ); 1.63 (d, J = 8.7Hz, 2H, CH Ph);
3
3
2
3
3
3
1
4
.13 (d, J = 15.2 Hz, 1H, H-3’b); 3.20 (d, J =8.1 Hz, 2H, H-4a and H-4b);
1H, H-1); 4.59 (m, 2H, H-1’ and CHpept); 4.92 (s, 2H, CH
2
Ph); 5.13 (m,
.25 (m, 1H, H-3’a); 3.59 (s, 1H, H-3); 3.75 (s, 3H, OCH ); 3.90 (s, 1H, H-
3
1
H, NHZ); 7.04–7.45 (m, 9H, Ar); 7.81 (s, 1H, NHpept); 8.58 (s, 1H,
’); 4.57 (s, 1H, CHpept); 4.79 (dd, J = 47.7 Hz, 12.7 Hz, 2H, CH Ph );
2
Z
13
NHind); C NMR (700 MHz, CDCl
3 3
) δ 17.7 (CH3pept), 21.8 (CH ), 26.8
.89 (bs, 1H, H-1); 5.30 (bs, 1H, NHZ); 6.78–7.64 (m, 15H, Ar and
13
(C-4), 42.1 (C-3’), 47.5 (C-1’), 52.3 (C-3), 52.5 (OCH ), 58.2 (C-1’), 66.4
3
NHpept); 8.86 (s, 1H, NHind); 8.93 (s, 1H, NH); C NMR (700MHz,
(
CHpept), 66.7 (CH
H-1 (H-3, CH3pept and CH
H-3’a and H-3’b), H-4b (H-3, H-4a, H-3’a and H-3’b), H-3’a and H-
3
’b (H-4a, H-4b), H-1’ and CHpept (CH3pept and CH , NHind), NHpept
2
Ph), 111.4–128.2 (Ar); ROESY (700 MHz, CDCl
3
)
CDCl ) δ 21.3 (CH ), 25.2 (C-4), 37.4 (C-3’), 38.4 (C-3), 39.9 (CH Ph),
3
3
2
3
); H-3 (H-1, H-4a, H-4b), H-4a (H-3, H-4b,
52.2 (CHpept), 53.1 (C-1), 53.2 (OCH ), 55.1 (C-1’), 67.2 (CH Ph ),
3 2 Z
1
11.8–129.1 (Ar); ROESY (700 MHz, CDCl ) H-1 (H-3, H-4a and H-4b,
3
3
H-3’a, NH); H-3 (H-1, H-4a and H-4b, H-3’a, H-3’b), H-4a and H-4b
H-1, H-3’b), H-3’a (H-1, H-3’b), H-3’b (H-1, H-4a and H-4b, H-1’,
H-3’a), H-1’ (H-1, H-3’b, CH Ph, NH), CH (CH , NH ), CH Ph
+
(
C
CH3pept and CH
3
); ESI m/z: 493 [M + H] ; exact mass calculated for
(
+
H N O
27 32 4 5
[M+ H] : 493.2445 found: 493.2458.
2
pept
3
pept
2
+
(
+
H-1’), NH
(CHpept), NH (H-1, H-1’); ESI m/z: 569 [M + H] , 591 [M
pept
2
Tcc(Z-D-Leu)CH -Ala-COOCH 5f
3
+
+
Na] ; exact mass calculated for C33
found: 569.2764.
trans 6c: Yield: 23%; yellowish foam; [α]
grad. 1) = 17.73 min; R (CHCl – Acetone 3 : 2) = 0.43; H NMR
700 MHz, CDCl ) δ 0.84 (m, 3H, CH ); 1.43 (m, 2H, CH Ph); 2.87 (m,
H, H-4b); 3.03 (m, 2H, H-3’a and H-3’b); 3.19 (m, 1H, H-4a); 3.51
m, 1H, H-3); 3.59 (s, 3H, OCH ); 4.21 (s, 1H, H-1’); 4.34 (bs, 1H, H-1);
.49 (m, 1H, CHpept); 4.87 (m, 1H, NHZ); 5.02 (dd, J = 24.0 Hz, 9.2Hz,
36 4 5
H N O [M+ H] : 569.2758
The ratio of cis/trans isomers determined before purification by 1H
NMR (200 MHz) was 100/0.
2
0
D
= +21.5 (c 1, CH
3
OH); t
R
1
20
(
(
1
(
4
2
f
3
cis 5f: Yield: 65%; yellowish foam; [α]
(grad. 1) = 17.03 min; R (CHCl
(700 MHz, CDCl ) δ 0.98 (dt, J = 16.7 Hz, J = 8,3Hz, 6H, CH
J = 7.3 Hz, 3H, CH3pept); 1.79 (m, 2H, CH CH(CH ); 1.95 (m, 1H,
CH CH(CH ); 2.93 (d, J = 14.5Hz, 1H, H-3’b); 3.10 (m, 1H, H-4b);
3.14 (m, 1H, H-4a), 3.49 (m, 1H, H-3’a); 3.76 (s, 3H, OCH ); 3.87
(bs, 1H, H-3); 4.54 (m, 1H, CHpept); 4.72 (t, J = 10.5 Hz, 1H, H-1’);
4.76 (s, 1H, H-1); 4.92 (dd, J = 33.1 Hz, J = 12.7 Hz, 2H, CH Ph);
5.15 (s, 1H, NHZ); 6.92–7.45 (m, 10H, Ar and NHind); 8.13 (s, 1H,
D 3 R
= +123.2 (c 1, CH OH); t
1
3
3
2
f
3
– Acetone 3 : 2) = 0.56; H NMR
); 1.51 (d,
3
3
3
2
3 2
)
2
3 2
)
1
3
2
H, CH Ph
Z
); 6.87–7.51 (m, 14H, Ar); 7.79 (s, 1H, NHpept); C NMR
) δ 22.3 (CH ), 24.6 (C-3), 37.3 (C-4), 39.9 (CH Ph),
9.4 (C-1’), 51.7 (CHpept), 51.9 (OCH ), 53.8 (C-1), 65.8 (C-3), 67.2
CH Ph ), 111.7–128.9 (Ar); ROESY (700 MHz, CDCl ) H-1 (H-1’,
3
(700 MHz, CDCl
3
3
2
4
(
3
2
2
Z
3
1
3
H-3’a and H-3’b); H-3 ( H-4a, H-3’a and H-3’b), H-4a (H-3, H-4b,
H-3’a and H-3’b), H-4b (H-4a, H-3’a and H-3’b), H-3’a and H-3’b
NHpept); 8.93 (s, 1H, NH); C NMR (700 MHz, CDCl
(CH3pept), 21.4 (CH ), 24.9 (CH CH(CH and C-4), 37.7 (C-3’),
39.9 (CH CH(CH ), 48.9 (C-1’), 49.0 (CHpept), 53.2 (OCH ), 55.0
(C-3), 60.0 (C-1), 67.6 (CH Ph), 111.8–128.6 (Ar); ROESY (700 MHz,
3
) δ 16.9
3
2
3 2
)
(
H-1, H-3, H-4a, H-4b), H-1’ (H-1, CH
2
Ph, NHZ), CHpept (CH
3
, NHpept),
2
3
)
2
3
+
CH Phe (H-1’), NHpept (CHpept); ESI-MS m/z: 569 [M+ H] , 591 [M
2
2
wileyonlinelibrary.com/journal/jpepsci
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
J. Pept. Sci. 2015; 21: 893–904

SYNTHESIS OF RIGID TRYPTOPHAN MIMETICS
CDCl ) H-1 (H-3, H-1’, CH CH(CH ) , CH CH(CH ) , NH); H-3 (H-1, H-4b,
H-4a); 3.12 (bs, 1H, H-3); 3.73 (s, 3H, OCH ); 4.15 (s, 1H, H-1’); 4.43
3
2
3 2
2
3 2
3
H-3’a, NH), H-4a (H-4b), H-4b (H-3a, H-3, H-3’a), H-3’a (H-3, H-4b, H-3’b),
H-3’b (H-3’a), H-1’ (H-1, CH CH(CH ) , CH CH(CH ) ), CHpept(CH3pept),
(s, 1H, CHpept); 4.91 (d, J = 9.4Hz, 1H, H-1); 5.01 (dd, J = 20.9 Hz,
J = 12.0 Hz, 2H, CH Ph); 5.14 (m, 1H, NHZ); 7.01–7.60 (m, 9H, Ar);
2
3 2
2
3 2
2
13
CH CH(CH ) (H-1, H-1’, CH CH(CH ) ), CH CH(CH ) (H-1, H-1’,
C NMR (700 MHz, CDCl ) δ 18.5 (CH ), 21.9 (CH3pept), 23.8 (C-4),
2
3 2
2
3 2
2
3 2
3 3
CH CH(CH ) , CH CH(CH ) , CH , NH), NH
(CHpept), NH (H-1, H-3,
24.8 (CH CH(CH ) ), 38.2 (C-3’), 39.8 (CH CH(CH ) ), 46.2 (C-1), 48.1
2 3 2 2 3 2
(C-1’), 51.1 (CHpept), 52.4 (C-3), 52.6 (OCH ), 67.8 (CH Ph), 111.4–
3 2
2
3 2
2
3 2
3
pept
+
CH CH(CH ) ); ESI m/z: 535 [M+H] ; exact mass calculated for
2
3 2
+
C H N O [M + H] : 535.2915, found: 535.2914.
0
130.5 (Ar); ROESY (700MHz, CDCl ) H-1 (H-3, CH3), H-3 (H-1, H-4a,
3
38
4
5
3
H-3’a and H-3’b), H-4a (H-3, H-4b, H-3’a and H-3’b), H-4b (H-4a, H-
3
’a and H-3’b), H-3’a and H-3’b (H-3, H-4a, H-4b), H-1’ (CH ), CH3
3
2 3
Tcc(Z-D-Phe)CH COOCH 5g
(H-1’), CHpept (CH CH(CH ) , CH CH(CH ) ), CH CH(CH ) (CHpept
,
2
3 2
2
3 2
2
3 2
The ratio of cis/trans isomers determined before purification by 1H
CH CH(CH ) , CH
), CH CH(CH ) (CH , CH CH(CH ) , CH3pept),
2
3 2
3pept 2 3 2 pept 2 3 2
+
NMR (200 MHz) was 100/0.
cis 5g: Yield: 39%; yellowish foam; [α] D = +58.5 (c 1, CH OH); t
CH3
(CH CH(CH ) , CH CH(CH ) ); ESI m/z: 535 [M + H] , 557 [M
pept 2 3 2 2 3 2
2
0
+
+
+ Na] ; exact mass calculated for C H N O [M+ H] : 535.2915
30 38 4 5
3
R
1
(
grad. 1) = 16.76 min; R
700 MHz, CDCl ) δ 1.42 (s, 3H, CH
.10 (s, 1H, H-3’b); 3.17 (d, J =15.2 Hz, 2H, H-4a and H-4b); 3.27 (d,
J = 9.7 Hz, 1H, H-3’a); 3.54 (m, 1H, H-3); 3.77 (s, 3H, OCH ); 4.44 (s,
H, H-1); 4.54 (bs, 1H, H-1’); 4.88 (s, 1H, CHpept); 5.09 (dd,
J = 40.2Hz, J = 13.6 Hz, 2H, CH Ph ); 5.44 (s, 1H, NHZ);7.07–7.49 (m,
4H, Ar); C NMR (700 MHz, CDCl ) δ 16.8 (CH ), 17.1 (CH Ph);
4.9 (C-3’), 37.1 (C-4), 48.8 (C-1), 49.3 (C-1’), 53.2 (OCH ), 58.7
Ph ), 111.5–129.1 (Ar); ROESY
) H-1 (H-3); H-3 (H-1, H-4a and H-4b, H-3’a, H-3’b),
H-4a and H-4b (H-3, H-3’a, H-3b); H-3’a (H-3, H-4a and H-4b,
H-3’b), H-3’b (H-3, H-4a and H-4b, H-3’a), H-1’ (CH Ph), CHpept
f
(CHCl
3
– Acetone 3 : 2)= 0.54; H NMR
); 1.54 (d, J = 7.0 Hz, 2H, CH Ph);
found: 535.2929.
trans 8a: Yield: 27%; yellowish foam; [α]
(grad. 1)= 17.23 min; R (CHCl – Acetone 3 : 2) = 0.32; H NMR
(700 MHz, CDCl ) δ 0.89 (m, 6H, CH3pept); 1.13 (m, 3H, CH ); 1.63
(dt, J = 14.1 Hz, J = 6.4Hz, 2H, CH CH(CH ); 1.70 (dq, J = 20.1 Hz,
J = 6.6 Hz, 1H, CH CH(CH ); 2.62 (m, 1H, H-4b); 2.71 (m, 1H, H-4a);
2.81 (d, J = 17.3 Hz, 2H, H-3’b and H-3’a); 3.39 (bs, 1H, H-3); 3.55 (s,
3H, OCH ); 3.72 (m, 1H, H-1); 3.85 (s, 1H, H-1’); 4.50 (s, 1H, NHZ);
4.61 (dd, J = 14.3 Hz, J = 7.0Hz, 1H, CHpept); 5.06 (t, J = 12.3Hz, 2H,
CH Ph); 6.24 (s, 1H, NH); 7.03–7.49 (m, 9H, Ar); 8.23 (s, 1H, NHpept);
8.97 (s, 1H, NHind); C NMR (700 MHz, CDCl
(CH3pept), 24.8 (CH CH(CH ), 27.6 (C-4), 38.5 (C-3’), 40.7 (CH
(CH ), 48.8 (C-1’), 51.0 (CHpept), 51.8 (C-1), 52.4 (C-3); 53.4 (OCH
66.9 (CH Ph), 111.2–129.3 (Ar); ROESY (700 MHz, CDCl ) H-1 (CH
20
(
3
3
2
D 3 R
= +27.9(c 1, CH OH); t
1
3
f
3
3
3
3
1
2
3 2
)
2
Z
2
3 2
)
1
3
1
2
3
3
2
3
3
(CHpept), 64.3 (C-3), 67.1 (CH
2
Z
(
700 MHz, CDCl
3
2
1
3
3
) δ 14.8 (CH
3
), 21.2
CH
2
2
)
3 2
2
+
(
CH
3
), CH
2
Ph (H-1’), CH
3
(CHpept); ESI m/z: 569 [M + H] , 591 [M
)
3 2
3
),
);
+
+
+
Na] ; exact mass calculated for C33
H N O
36 4 5
[M + H] : 569.2758
2
3
3
found: 569.2783.
H-3 (H-4b, H-3’b and H-3’a), H-4a (H-4b, H-3’a and H-3’b, NH), H-4b
H-3, H-4a, H-3’a and H-3’b, NH), H-3’a and H-3’b (H-3, H-4a, H-4b,
(
NH), H-1’ (CH
, NHpept), CH
(CH3pept, CHpept), CH3pept (CH
3
), CH
3
(H-1’, NHZ), CHpept (CH
2
CH(CH
3
)
2
, CH
2
CH(CH
3
)
Tcc(Z-D-Val)CH -Ala-COOCH 5h
2
3
2
2
CH(CH
)
3 2
(CH3pept, CHpept, NHpept), CH
2
CH(CH
3
)
2
The ratio of cis/trans isomers determined before purification by 1H
2 3 2 2 3 2
CH(CH ) , CH CH(CH ) ), NHpept
NMR (200 MHz) was 100/0.
cis 5h: Yield: 39%; yellowish foam; [α] D = +8.4 (c 1, CH OH); t
(CH CH(CH ) , CH ), NH (H-4a, H-4b, H-3’a and H-3’b), NH (Ar);
2
3 2
pept
ind
20
+
+
ESI m/z: 535 [M + H] , 557 [M+ Na] ; exact mass calculated for
3
1
R
+
(
grad. 1) = 15.55 min; R (CHCl3 – Acetone 3 : 2)= 0.52; H NMR
C H N O [M+ H] : 535.2915 found: 535.2940.
30 38 4 5
f
(
700 MHz, CDCl ) δ 1.08 (d, J = 6.4Hz, 3H, CH ); 1.23 (d, J = 6.5Hz,
3
3
3
H, CH ); 1.48 (d, J = 7.4 Hz, 3H, CH3pept); 2.13 (m, 1H, CH(CH3)2);
3
2
.80 (d, J = 13.8Hz,1H, H-3’b); 3.11 (dd, J = 13.7 Hz, J = 9.1Hz, 1H,
Tcc(Z-L-Ile)CH -Leu-COOCH 8b
2
3
H-4a and H-4b); 3.42 (dd, J = 15.1 Hz, J = 11.8 Hz, 1H, H-3’a); 3.77
s, 3H, OCH ); 3.90 (s, 1H, H-3); 4.22 (m, 1H, H-1’); 4.53 (m, 1H, CHpept);
(
The ratio of cis/trans isomers determined before purification by 1H
3
4
.94 (s, 2H, CH Ph); 4.99 (s, 1H, H-1); 5.11 (s, 1H, NHZ); 6.98–7.47 (m,
NMR (200 MHz) was 0/100.
trans 8b: Yield: 39%; yellowish foam; [α] D = +35.7 (c 1, CH OH); t
2
13
20
10H, Ar and NHind); 8.30 (bs, 1H, NHpept); 8.85 (s, 1H, NH); C NMR
), 20.0 (CH ), 20.6 (CH ), 25.2 (C-4),
3
R
1
(700 MHz, CDCl ) δ 16.6 (CH
(grad. 1)= 18.50 min; R (CHCl3 – Acetone 3 : 2) = 0.32; H NMR
3
3pept
3
3
f
2
8.7 (CH(CH ) ), 38.1 (C-3’), 48.9 (CH ), 53.0 (OCH ), 55.7 (C-3),
(700 MHz, CDCl ) δ 0.91 (m, 6H, CH ); 0.96 (m, 6H, CH3pept); 1.19
3
2
pept
3
3
3
5
6.8 (C-1), 57.0 (C-1’), 66.6 (CH Ph), 111.8–128.2 (Ar); ROESY
(m, 1H, CH(CH )CH CH ); 1.21 (dd, J = 13.8Hz, J = 7.2Hz, CH CH
2
3 2 3 2
(
700 MHz, CDCl ) H-1 (H-3, H-1’, NH); H-3 (H-1, H-4a and H-4b,
(CH ) ); 1.68 (m, 2H, CH CH(CH ) ); 1.73 (m, 2H, CH(CH )CH CH );
3 2 2 3 2 3 2 3
3
H-3’a, H-3’b), H-4a and H-4b (H-3, H-3’a, H-3’b), H-3’a (H-3, H-4a
and H-4b, H-3’b), H-3’b (H-3, H-4a and H-4b, H-3’a), H-1’ (H-1, CH
2.35 (m, 2H, H-3’a and H-3’b); 2.60 (m, 1H, H-4b); 2.73 (m, 1H, H-
4a); 3.60 (s, 3H, OCH ); 3.73 (t, J = 8.3 Hz, 1H, H-3); 4.02 (s, 1H, H-1’);
4.12 (dd, J = 14.3Hz, J = 7.1Hz, 1H, H-1); 4.60 (d, J = 5.5Hz, 1H,
CHpept); 5.07 (s, 2H, CH Ph); 5.59 (s, 1H, NHZ); 6.43–7.43 (m, 9H,
3
(
CH
3 2 3 3 2 3
) , CH , NH), CH(CH ) (H-1’, CH ), CHpept(CH3pept, NHpept),
+
NHpept (CHpept), NH (H-1, H-1’); ESI m/z: 521 [M + H] , 543 [M
+
2
+
+
13
Na] ; exact mass calculated for C29
H N O
36 4 5
[M+ H] : 521.2772
Ar); 8.04 (s, 1H, NHpept); C NMR (700 MHz, CDCl
17.0 (CH ), 21.6 (CH3pept), 24.9 (CH CH(CH ), 26.0 (CH(CH
CH CH ), 29.5 (CH CH(CH ), 35.6 (C-4), 40.0 (C-3’), 40.9 (CH(CH
CH CH ), 50.8 (CHpept), 51.8 (C-3), 53.2 (OCH
), 67.1 (CH Ph), 111.3–128.3 (Ar); ROESY (700 MHz, CDCl
); H-3 (H-4b), H-4a (H-4b, H-3’a, H-3’b), H-4b (H-3, H-4a, H-
3 3
) δ 10.7 (CH ),
found: 521.2770.
3
2
)
3 2
3
)
2
3
2
)
3 2
3
)
2
3
3
), 59.3 (C-1’), 60.3 (C-
) H-1 (H-
2 3
Tcc(Z-L-Ala)CH -Leu-COOCH 7a and 8a
1
2
3
The ratio of cis/trans isomers determined before purification by 1H
1’, CH
3
NMR (200 MHz) was 39/61.
3’a, H-3’b), H-3’a (H-4a, H-4b, H-3’b), H-3’b (H-4a, H-4b, H-3’a), H-1’
(H-1, CH(CH )CH CH , NHZ), CH(CH )CH CH (H-1’, CH(CH )CH CH
CH , NHZ), CH(CH )CH CH (CH(CH )CH CH (CH(CH
CH CH , CH(CH )CH CH ), CHpept (CH CH(CH CH(CH
(CH CH(CH CH3pept), CH CH(CH (CH
CHpept), NHpept (CHpept), NHZ (CH(CH )CH CH
2
0
cis 7a: Yield: 18%; yellowish foam; [α]
grad. 1) = 17.15 min; R (CHCl – Acetone 3 : 2)= 0.63; H NMR
700 MHz, CDCl ) δ 0.78–0.99 (m, 6H, CH3pept); 1.43 (bs, 3H, CH );
.55 (bs, 2H, CH CH(CH ); 1.76 (bs, 1H, CH CH(CH ); 2.41 (d,
J = 13.0Hz, 1H, H-4b); 2.51 (m, 2H, H-3’a and H-3’b); 2.60 (m, 1H,
D
= À29.9 (c 1, CH
3
OH); t
R
3
2
3
3
2
3
3
2
3
,
3
)
)
3 2
1
(
f
3
3
3
2
3
3
2
3
, CH
3
), CH
), CH
3
(
3
3
2
3
3
2
3
2
)
3 2
2
1
2
)
3 2
2
)
3 2
2
)
3 2
,
2
3
)
2
2
CH(CH
3 2
) ,
CH3pept,
3
2
3
); ESI m/z: 577 [M
J. Pept. Sci. 2015; 21: 893–904
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/jpepsci

SLUPSKA ET AL.
+
+
+
+
5
H] , 599 [M + Na] ; exact mass calculated for C H N O [M+ H] :
4b, H-3’a, H-3’b), H-4b (H-3, H-4a, H-3’a, H-3’b), H-3’a (H-3, H-4a,
H-4b, H-3’b, NHpept), H-3’a (H-3, H-4a, H-4b, H-3’b, NHpept), H-1’
3
3 44 4 5
77.3384 found: 577.3394.
(
H-1, H-3, NH), CH(CH ) ( H-1, CH , NH, NHZ), CH (CH(CH ) ),
3 2 3 3 3 2
CHpept (CH CH(CH ) , CH CH(CH ) , NH ), CH CH(CH ) (CH CH
2
3 2
2
3 2
pept
2
3 2
2
Tcc(Z-L-Phe)CH -Leu-COOCH 7c and 8c
2
3
(
CH ) , CH3pept, CHpept), CH CH(CH ) (CH CH(CH ) , CH3pept,
3 2 2 3 2 2 3 2
The ratio of cis/trans isomers determined before purification by 1H
CH CH(CH ) ), CH
(CH CH(CH ) , CH CH(CH ) ), NH
(H-3,
2
3 2
3pept
2
3 2
2
3 2
pept
NMR (200 MHz) was 21/79.
H-3’a, H-3’b, CHpept, CH CH(CH ) , CH CH(CH ) ), NH (H-1, H-1’, CH
2 3 2 2 3 2
2
0
+
cis 7c: Yield: 18%; yellowish foam; [α] = À7.9 (c 1, CH OH); t
(CH ) , Ar), NHZ (H-1, H-1’, CH Ph, CH(CH ) ); ESI m/z: 563 [M+ H] ;
3 2 2 3 2
D
3
R
+
(
grad. 1) = 18.37 min, t (grad. 1)= 15.03 min; R (CHCl – Acetone
exact mass calculated for C H N O [M+ H] : 563.3228 found:
32 42 4 5
R
f
3
1
3
2
1
3
4
8
(
(
6
:2) = 0.49; H NMR (700 MHz, CDCl ) δ 0.94 (m, 6H, CH ); 1.37 (m,
563.3231.
3
3
H, CH Ph); 1.64 (m, 3H, CH CH(CH ) ); 2.61 (m, 1H, H-4b); 2.87 (m,
2
2
3 2
H, H-4a); 3.04 (m, 2H, H-3’a and H-3’b); 3.69 (s, 1H, H-3); 3.73 (s,
Tcc(Z-D-Ala)CH
2
-Leu-COOCH
3
7e
H, OCH ); 4.35 (s, 1H, H-1’); 4.53 (s, 1H, CHpept); 4.69 (s, 1H, H-1);
3
.70 (m, 1H, NHZ); 5.07 (m, 2H, CH
2
Ph
C NMR (700 MHz, CDCl
), 27.9 (C-4), 28.3 (CH Ph), 37.3 (C-3’), 41.2 (CH
), 50.8 (C-1), 52.4 (OCH ), 54.9 (C-1’), 63.8 (C-3), 66.4 (CHpept),
6.7 (CH Ph), 111.4–126.6 (Ar); ROESY (700 MHz, CDCl ) H-1 (CH Ph,
NHind); H-3 (H-1’, H-4a, H-4b, H-3’a and H-3’b), H-4a (H-4b, H-3), H-4b
H-4a, H-3), H-3’a and H-3’b (H-3, H-1’), H-1’ (H-3, H-3’a and H-3’b),
, CH CH(CH ), CH CH(CH (CHpept, CH ), CH (CH CH
), NHind (H-1, Ar); ESI m/z: 611 [M + H] ; exact mass calculated
Z
); 6.95–7.36 (m, 14H, Ar);
) δ 22.5 (CH ), 24.8
CH
The ratio of cis/trans isomers determined before purification by 1H
1
3
.45 (s, 1H, NHind
)
3
3
NMR (200 MHz) was 100/0.
20
CH
CH
2
CH(CH
)
3 2
2
2
cis 7e: Yield: 43%; yellowish foam; [α]
(grad. 1) = 17.19 min; R (CHCl – Acetone 3 : 2) = 0.61; H NMR
(700 MHz, CDCl ) δ 0.97 (dd, J = 21.5 Hz, J = 6.6Hz, 6H, CH3pept);
1.50 (d, J = 7.0 Hz, 3H, CH ); 1.66 (m, 2H, CH CH(CH ); 1.86 (m, 1H,
CH CH(CH ); 2.78 (d, J = 11.9Hz, 1H, H-3’b); 3.09 (m, 1H, H-4b);
3.15 (dd, J = 16.0 Hz, J = 4.2 Hz, 1H, H-4a); 3.31 (m, 1H, H-3’a); 3.78
(s, 3H, OCH ); 3.89 (bs, 1H, H-3); 4.47 (m, 1H, CHpept); 4.82 (bs, 1H,
H-1); 4.84 (bs, 1H, H-13); 4.94 (q, J = 12.7 Hz, 2H, CH Ph); 6.93 (d,
J = 9.9 Hz, 1H, NHZ); 6.98–7.49 (m, 9H, Ar); 8.83 (s, 1H, NHind); 8.95
D 3 R
= +58.8 (c 1, CH OH); t
1
)
3 2
3
f
3
2
3
2
3
3
2
3 2
)
(
2
3 2
)
CHpept (CH
3
2
)
3 2
2
3
)
2
3
3
2
+
(
CH
for C36
trans 8c: Yield: 42%; yellowish foam; [α]
grad. 1) = 18.45 min, t (grad. 2)= 15.14 min; R
:2) = 0.34; H NMR (700 MHz, CDCl ) δ 0.93 (m, 6H, CH
H, CH Ph and CH CH(CH ); 1.97 (bs, 1H, CH CH(CH
)
3 2
3
+
H N O
42 4 5
[M+ H] : 611.3228 found: 611.3246.
2
2
D
0
= +31.9 (c 1, CH
(CHCl – Acetone
); 1.61 (m,
); 2.48
3 R
OH); t
1
3
(
3
4
R
f
3
(s, 1H, NHpept); C NMR (700MHz, CDCl
22.7 (CH3pept), 24.6 (C-4), 24.9 (CH CH(CH
39.7 (C-4), 46.3 (C-1), 52.0 (OCH ), 52.4 (CHpept), 55.8 (C-3), 60.2
(C-1’), 67.2 (CH Ph), 111.8–128.2 (Ar); ROESY (700 MHz, CDCl
H-1 (H-3, CH , NHind); H-3 (H-1, H-4b, H-3’a, H-3’b), H-4a (H-3b,
H-3’b), H-4b (H-3, H-4a, H-3’a), H-3’a (H-3, H-4b, H-3’b), H-3’b
(H-3, H-4a, H-3’a), H-1’ (CH , NHZ), CH (H-1, H-1’, NHZ), CHpept
(CH CH(CH ) , NH ), CH CH(CH ) (CH CH(CH ) , CH3pept),
3
) δ 17.2 (CH
3
), 21,9 (CH3pept),
1
3
3
2
3
)
2
), 39.0 (CH
2
CH(CH ),
3 2
)
2
2
3
)
2
2
3
)
2
3
(m, 1H, H-4b); 2.71 (m, 2H, H-3’a and H-3’b); 2.81(m, 1H, H-4a);
2
3
)
3.33 (s, 1H, H-3); 3.57 (s, 3H, OCH
4.68 (s, 1H, H-1); 4.98 (m, 2H, CH
7.31 (m, 14H, Ar); 7.45 (s, 1H, NHpept); 8.45 (s, 1H, NHind); C NMR
3
); 4.53 (s, 2H, H-1’ and CHpept);
Ph ); 5.81 (bs, 1H, NHZ); 7.12–
3
2
Z
1
3
3
3
(
700 MHz, CDCl ) δ 22.5 (CH ), 24.8 (CH CH(CH ) ), 28.1(C-4), 35.5
3 3 2 3 2
2
3 2
pept
2
3 2
2
3 2
(
C-3’), 41.1 (CH Ph), 42.5 (CH CH(CH ) ), 50.6 (C-1), 52.2 (OCH ),
CH CH(CH ) (CH CH(CH ) , CH3pept, CHpept, NHpept), CH3pept
2 3 2 2 3 2
2
2
3 2
3
5
2.2 (C-3), 55.4 (C-1’), 56.9 (CHpept), 66.7 (CH2Ph ), 111.9–128.3
(CH CH(CH ) , CH CH(CH ) ), NHpept (CH CH(CH ) , CHpept),
2 3 2 2 3 2 2 3 2
Z
+
(Ar); ROESY (700 MHz, CDCl ) H-1 (CH Ph and CH CH(CH ) ); H-3
NHind (H-1, Ar), NHZ (H-1’, CH ); ESI m/z: 535 [M + H] , 557
3
3
2
2
3 2
+
+
(
3
(
H-1’ and CHpept, H-4b, H-3’a and H-3’b), H-4a (H-4b, H-3’a and H-
’b, H-1’ and CHpept), H-4b (H-4a, H-3’a and H-3’b), H-3’a and H-3’b
H-4a, H-4b, Ar, NHpept), H-1’ and CHpept (H-3, H-4a, H-3’a and
H-3’b, Ar, NHpept, NHind), CH Ph and CH CH(CH ) (H-1, CH CH
[M + Na] ; exact mass calculated for C H N O [M + H] :
30 38 4 5
535.2915 found: 535.2924 Df. 1.68 ppm.
2
2
3 2
2
Tcc(Z-D-Leu)CH -Leu-COOCH 7f
2
3
(CH ) , CH Leu), CH Leu (CH CH(CH ) , CH Ph and CH CH(CH ) ),
3 2 3 3 2 3 2 2 2 3 2
NHpept (H-1’ and CHpept), NHind (H-1’ and CHpept); ESI-MS m/z: 611
The ratio of cis/trans isomers determined before purification by 1H
+
+
[
M+ H] ; exact mass calculated for C H N O [M+ H] : 611.3228
NMR (200 MHz) was 100/0.
cis 7f: Yield: 67%; yellowish foam; [α] = +50.9 (c 1, CH OH); t
D 3 R
1
3
6 42 4 5
20
found: 611.3246.
(
grad. 1) = 18.61 min; R (CHCl3 – Acetone 3 : 2) = 0.52; H NMR
f
(
700 MHz, CDCl ) δ 0.86–1.03 (m, 12H, CH ); 1.54 (ddd, J = 13.0 Hz,
3
3
2 3
Tcc(Z-L-Val)CH -Leu-COOCH 8d
J = 5.3 Hz, J = 3.3 Hz, 1H, CH CH(CH ) ); 1.67 (m, 1H, CH CH(CH )
2
3 2
2
3
The ratio of cis/trans isomers determined before purification by 1H
2 3 2 3 2
2pept); 1.79 (m, 2H, CH CH(CH )2pept); 1.93 (m, 2H, CH CH(CH ) );
NMR (200 MHz) was 0/100.
2.88 (d, J = 14.3 Hz, 1H, H-3’b); 3.11 (m, 1H, H-4b); 3.16 (m, 1H, H-
4a); 3.53 (m, 1H, H-3’a); 3.78 (s, 3H, OCH ); 3.89 (bs, 1H, H-3); 4.51
(m, 1H, CHpept); 4.72 (t, J = 10.5 Hz, 1H, H-1’); 4.78 (s, 1H, H-1); 4.92
(m, 2H, CH Ph); 5.15 (m, 1H, NHZ); 6.92–7.64 (m, 9H, Ar); 8.29 (s,
1H, NHpept); 8.51 (s, 1H, NH); 8.91 (s, 1H, NHind
CDCl ) δ 21.3 (CH ), 23.1 (CH3pept), 25.1 (C-4), 38.4 (C-3’), 39.5
(CH CH(CH 2pept and CH CH(CH 2pept), 40.1 (CH CH(CH and
CH CH(CH ), 49.2 (C-1’), 52.2 (CHpept), 53.1 (OCH ), 54.9 (C-3),
60.0 (C-1), 67.6 (CH Ph), 111.9–128.5 (Ar); ROESY (700 MHz, CDCl
H-1 (H-3, CH CH(CH , NH, NHind); H-3 (H-1, H-4b, H-3’a, H-3’b), H-
4a (H-4b, H-3’a, H-3’b), H-4b (H-3, H-4a, H-3’a, H-3’b), H-3’a (H-3, H-
4a, H-4b, H-3’b), H-3’b (H-3, H-4a, H-4b, H-3’a), H-1’ (CH CH(CH
CH CH(CH , NH), CH CH(CH (H-1’, CH CH(CH ), CH CH(CH
(H-1, H-1’, CH CH(CH , CH , NH), CHpept (CH CH(CH CH
(CH CH(CH 2pept (CH CH(CH
2
0
trans 8d: Yield: 51%; yellowish foam; [α]
grad. 1) = 18.02 min; R (CHCl – Acetone 3 : 2) = 0.46; H NMR
700 MHz, CDCl ) δ 0.92 (q, J = 5.4 Hz, 6H, CH3pept); 0.99 (m, 6H,
); 1.57 (m, 1H, CH CH(CH ); 1.67 (m, 2H, CH CH(CH ); 2.02
m, 1H, CH(CH ); 2.37 (m, 1H, H-3’b); 2.41 (d, J = 10.5 Hz, 1H, H-
b); 2.51 (d, J = 14.2 Hz, 1H, H-3’a); 2.72 (d, J = 13.6 Hz, 1H, H-4a);
.19 (bs, 1H, H-3); 3.57 (s, 3H, OCH ); 3.98 (m, 1H, H-1); 4.36 (s, 1H,
Ph); 5.59 (m, 1H, NHZ);
.89 (m, 1H, NHind); 6.86–7.47 (m, 9H, Ar); 7.91 (s, 1H, NHpept); 8.34
D
= +23.3 (c 1, CH
3
OH); t
R
3
1
(
(
f
3
3
2
1
3
CH
(
4
3
3
2
3
)
2
2
3
)
2
)
C NMR (700 MHz,
3
)
2
3
3
2
3
)
2
3
)
2
3 2
)
3
2
)
3 2
3
H-1’); 4.64 (m, 1H, CHpept); 5.11 (m, 2H, CH
6
2
2
3
)
2
3 2
)
1
3
(
s, 1H, NH); C NMR (700 MHz, CDCl
4.95 (CH CH(CH ); 29.1 (C-4), 29.7 (CH(CH
), 42.7 (C-3’), 50.6 (CHpept), 53.7 (C-3), 52.3 (OCH
C-1), 67.1 (CH Ph ), 111.0–128.4 (Ar); ROESY (700MHz, CDCl
H-1’, CH(CH , NH), H-3 (H-4b, H-3’a, H-3’b, H-1’, NHpept), H-4a (H-
3
) δ 19.6 (CH3pept), 20.1 (CH
), 41.1 (CH CH(CH
), 57.0 (C-1’), 59.4
) H-1
3
),
2
2
)
3 2
)
3 2
2
3
)
2
3 2
) ,
2
3
2
)
3 2
2
3
)
2
2
3
)
2
2
3 2
)
(
(
2
Z
3
2
3
)
2
3
2
3
)
2pept, CH
2
3
)
2
3
)
2pept, NHpept), CH
2
3
)
2
3
)2pept, CH3pept),
wileyonlinelibrary.com/journal/jpepsci
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
J. Pept. Sci. 2015; 21: 893–904

SYNTHESIS OF RIGID TRYPTOPHAN MIMETICS
CH CH(CH )
(CH CH(CH ) , CH3pept, CHpept), NHpept (CHpept),
3 2pept
under the Operational Programme Innovative Economy, 2007–
2013, and with the use of CePT infrastructure financed by the same
EU programme.
2
3 2pept
2
+
NH (H-1, H-1’, CH CH(CH ) ), NH (H-1, Ar); ESI m/z: 577 [M + H] ;
exact mass calculated for C H N O [M + H] : 577.3384 found:
2
3 2
ind
+
33 44 4 5
577.3388.
Tcc(Z-D-Phe)CH -Leu-COOCH 7g
2
3
References
The ratio of cis/trans isomers determined before purification by 1H
1
Nongonierma AB, FitzGerald RJ. Tryptophan-containing milk
NMR (200 MHz) was 100/0.
cis 7g: Yield: 38%; yellowish foam; [α] D = +67.1 (c 1, CH OH); t
protein-derived dipeptides inhibit xanthine oxidase. Peptides 2012;
20
4
4: 263–272.
3
1
R
2 Yang Y, Mishra VK, Chen M, Duffee E, Dimmitt R, Harmon CM. Molecular
characterization of human melanocortin-5 receptor ligand-receptor
interaction. Biochemistry 2013; 52: 1737–1745.
3 Pulka K, Feytens D, Misicka A, Tourwé D. New tetracyclic tetrahydro-β-
carbolines as tryptophan-derived peptidomimetics. Mol. Divers. 2011;
(
grad. 1) = 18.59 min; R (CHCl3 – Acetone 3 : 2)= 0.46; H NMR
f
(
700 MHz, CDCl ) δ 0.96 (dd, J = 16.4 Hz, J = 6.2 Hz, 6H, CH ); 1.67
3
3
(
m, 2H, CH Ph); 1.76 (m, 1H, CH CH(CH ) ); 1.83 (m, 2H, CH CH
2 2 3 2 2
(
CH ) ); 3.12 (d, J =15.2Hz, 1H, H-4b); 3.20 (d, J =15.2 Hz, 2H, H-3’a
3 2
1
4: 97–108.
and H-3’b); 3.25 (m, 1H, H-4a); 3.59 (m, 1H, H-3); 3.75 (s, 3H, OCH3);
.90 (s, 1H, H-1’); 4.57 (s, 1H, CHpept); 4.79 (dd, J = 47.7 Hz,
J = 12.7 Hz, 2H, CH Ph ), 4.89 (s, 1H, H-1); 5.30 (m, 1H, NHZ); 6.78–
4
5
Gibson SE, Guillo N, Tozer MJ. Towards control of χ-space:
conformationally constrained analogues of Phe, Tyr, Trp and His.
Tetrahedron 1999; 5: 585–615.
Ortar G, Petrocellis LD, Moriello AS, Allarà M, Morera E, Nalli M, Marzo VD.
Tetrahydro-β-carboline derivatives targeting fatty acid amide hydrolase
(FAAH) and transient receptor potential (TRP) channels. Bioorg. Med.
Chem. Lett. 2013; 23: 138–142.
3
2
Z
7
.64 (m, 15H, Ar and NHind); 8.86 (s, 1H, NHpept); 8.93 (s, 1H, NH);
1
3
C NMR (700 MHz, CDCl ) δ 21.3 (CH ), 24.9 (CH CH(CH ) ); 25.2
3
3
2
3 2
(
C-4), 37.4 (C-3’), 38.4 (C-1), 39.9 (CH Ph), 41.2 (CH CH(CH ) ) 52.2
2 2 3 2
(
CHpept), 53.1 (C-1), 53.2 (OCH ), 55.1 (C-1’), 67.2 (CH Ph ), 111.8–
3
2
Z
6
7
Ahmeda NS, Ali AH, El-Nashar SM, Gary BD, Fajardo AM, Tinsley HN,
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1991; 113: 2275–2283.
1
29.1 (Ar); ROESY (700 MHz, CDCl ) H-1 (H-3, H-3’a and H-3’b, NH);
3
H-3 (H-1, H-4a), H-4a (H-3, H-4b, H-3’a and H-3’b), H-4b (H-4a, H-
’a and H-3’b), H-3’a and H-3’b (H-1, H-4a, H-4b), H-1’ (H-1, CH Ph,
NH), CH Ph (H-1’), CHpept (CH CH(CH , CH CH(CH
CH CH(CH (CH CH(CH , CH , CHpept), CH CH(CH
CH , CH , CHpept), CH (CH CH(CH , CH CH(CH
CHpept), NH (H-1, H-1’); ESI m/z: 611 [M + H] ; exact mass calculated
3
2
2
2
)
3 2
2
3 2
) , NHpept),
2
)
3 2
2
)
3 2
3
2
3 2 2
) (CH CH
(
(
)
3 2
3
3
2
)
3 2
2
3 2
) ), NHpept
+
+
8 Gupta AK, Varshney K, Singh N, Mishra V, Saxena M, Palit G, Saxena AK.
Identification of Novel Amino Acid Derived CCK-2R Antagonists As
Potential Antiulcer Agent: Homology Modeling, Design, Synthesis, and
Pharmacology. J. Chem. Inf. Model. 2013; 53: 176–187.
42 4 5
for C36H N O [M + H] : 611.3228 found: 611.3255.
2 3
Tcc(Z-D-Val)CH -Ala-COOCH 7h
9
Yao K, Zhao M, Zhang X, Wang Y, Li L, Zheng M, Peng S. A class of oral
N-[(1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carbonyl]-N’-
The ratio of cis/trans isomers determined before purification by 1H
(
amino-acid-acyl)hydrazine: Discovery, synthesis, in vitro anti-platelet
NMR (200 MHz) was 100/0.
aggregation/in vivo anti-thrombotic evaluation and 3D QSAR analysis.
Eur. J. Med. Chem. 2011; 46: 3237–3249.
20
cis 7 h: Yield: 67%; yellowish foam; [α]
grad. 1) = 18.00 min; R (CHCl – Acetone 3 : 2)= 0.52; H NMR
700 MHz, CDCl ) δ 0.96 (m, 6H, CH3pept); 1.08 (m, 3H, CH ); 1.19
m, 3H, CH ); 1.65 (m, 1H, CH(CH ); 1.77 (m, 2H, CH CH(CH );
.17 (m, 1H, CH CH(CH ); 2.84 (d, J = 14.5 Hz, 1H, H-3’b); 3.12 (m,
H, H-4a and H-4b); 3.43 (d, J = 14.7 Hz, 1H, H-3’a); 3.75 (s, 3H,
); 3.87 (s, 1H, H-3); 4.22 (m, 1H, H-1’); 4.52 (dd, J = 14.5 Hz,
J = 7.3 Hz, 1H, H-1); 4.93 (m, 2H, CH Ph); 4.98 (m, 1H, CHpept); 5.11
D 3 R
= +40.5 (c 1, CH OH); t
1
(
f
3
1
0 Pictet A, Spengler T. Formation of isoquinoline derivatives by the action
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(
3
3
(
3
)
3 2
2
3 2
)
1
2
2
2
3 2
)
2011; 50: 8538–8564.
OCH
3
1
1
1
2 Tatsui G. Synthesis of carboline derivatives. Yakugaku Zasshi 1928; 48:
453–459.
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2
(
s, 1H, NHZ); 6.97–7.43 (m, 9H, Ar); 8.35 (s, 1H, NHpept); 9.02 (s, 1H,
1
3
NH); C NMR (700MHz, CDCl ) δ 19.8 (CH
), 20.2 (CH ), 24.7
3pept 3
3
(
CH CH(CH ) ); 25.1 (C-4), 28.7 (CH CH(CH ) ), 39.7 (CH(CH ) ), 42.7
2 3 2 2 3 2 3 2
(
C-3’), 51.7 (C-1), 52.8 (OCH ), 55.7 (C-3), 55.9 (CHpept), 57.0 (C-1’),
3
6
6.6 (CH Ph), 111.8–128.1 (Ar); ROESY (700MHz, CDCl ) H-1 (H-3,
2
3
CH(CH ) , CH ); H-3 (H-1, H-4a and H-4b, H-3’a, H-3b), H-4a and H-
3
2
3
4b (H-3, H-3’b), H-3’a (H-3’b), H-3’b (H-3, H-4a and H-4b, H-3’a,
1
NHpept), H-1’ (CH(CH ) , NHZ, NH), CH(CH ) (H-1’, CH , NH, NHZ),
3 2
3 2
3
CH3 (CH(CH3)2), CHpept(CH CH(CH ) , CH CH(CH ) , NHpept),
2
3 2
2
3 2
CH CH(CH ) (CH CH(CH ) , CH3pept, CHpept), CH CH(CH ) (CH CH
2
3 2
2
3 2
2
3 2
2
1
(
CH ) , CH3pept, CHpept), CH3pept (CH CH(CH ), CH CH(CH ) ), NH
3 2 2 3 2 3 2 pept
(
H-3’b, CHpept, CH CH(CH ) , CH CH(CH ) ), NH (H-1’, CH(CH ) , Ar),
2 3 2 2 3 2 3 2
+
NHZ (H-1’, CH(CH ) ); ESI m/z: 563 [M + H] ; exact mass calculated
for C H N O [M + H] : 563.3228 found: 563.3252.
3
2
+
3
2 42 4 5
1
9 Grigg R, Gunaratne HQN, McNaghten EJ. Observations on the Pictet-
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The study was carried out at the Biological and Chemical Research
Centre, University of Warsaw, established within the project co-
financed by EU from the European Regional Development Fund
J. Pept. Sci. 2015; 21: 893–904
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
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wileyonlinelibrary.com/journal/jpepsci
Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
J. Pept. Sci. 2015; 21: 893–904