‘Double chiral’ new members of calixsalen family

Article abstract of DOI:10.1016/j.tetasy.2017.08.021

Synthesis and X-ray diffraction studies on the first examples of ‘double chiral’ calixsalens are presented. In these molecules, one can clearly distinguish two chiral zones. The first one is made by the macrocycle base, whereas the second chiral zone is s

Full text of DOI:10.1016/j.tetasy.2017.08.021

Tetrahedron: Asymmetry xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
‘Double chiral’ new members of calixsalen family
Małgorzata Petryk a,b, Agnieszka Janiak a, Marcin Kwit a,b,
⇑
a Department of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61 614 Poznan, Poland
b Wielkopolska Center for Advanced Technologies (WCAT), Umultowska 89C, 61 614 Poznan, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Synthesis and X-ray diffraction studies on the first examples of ‘double chiral’ calixsalens are presented.
In these molecules, one can clearly distinguish two chiral zones. The first one is made by the macrocycle
base, whereas the second chiral zone is set up of the additional chirality elements in the tail of the mole-
cule. The ‘double chiral’ calixsalens are formed through cyclocondensation between chiral vicinal dia-
mine of trans-1,2-diaminocyclohexane type and chiral C-5 substituted 2-hydroxyisophthalaldehyde
derivatives. The absolute configuration of the dialdehyde did not affect the yield of the macrocyclization
reaction. The presence of secondary amides in the tail part of the macrocycle leads to formation of hydro-
gen bonding network in the solid state, while sterical hindrance preserve interdigitation, thus, ‘double
chiral’ calixsalens do not form aggregates typical for other calixsalens.
Received 1 August 2017
Accepted 24 August 2017
Available online xxxx
Dedicated to the memory of Dr. Howard
Flack
Ó 2017 Elsevier Ltd. All rights reserved.
1. Introduction
for 1,3-dialdehydes, the primary [3+3] cyclocondensation products
sometimes contracted to the [2+2] macrocycles. The introduction
Despite recent progress, a rational and controllable synthesis of
macrocyclic compounds still represents a formidable challenge.1
Among the reactions developed so far, those based on dynamic
covalent chemistry have gained more and more popularity. The
success of dynamic covalent chemistry-based macrocyclization
reactions relies on the reversibility of bond formation and struc-
tural predisposition of substrates to form strain-free macrocyclic
structures under thermodynamic conditions.2
of a hydroxyl group at the C-2 position of isophthalaldehyde has
a profound effect on the structure and stability of the product.
[3+3] Cyclocondensation between enantiomerically pure (R,R)-1
and various C5-substituted 2-hydroxyisophthalaldehydes of the
general formula 2, provides calixarene-like chiral macrocyclic
ligands, of the general formula 3 (Scheme 1).10,11 Due to their
vase-like structure and the presence of three salen moieties within
the macrocycle skeleton, these compound are dubbed ‘calixsalens’.
Discovered at the beginning of 21st century thermodynamically
controlled, reversible cycloimination reactions between enan-
tiomerically pure vicinal diamine, such as trans-1,2-diaminocyclo-
Calixsalens constitute a relatively unexplored class of chiral
ligands, capable of forming multimetal complexes of diverse func-
tions and exhibiting catalytic or receptor properties.12
hexane
1
and terepthalaldehyde, provided the triangular
Each of the calixsalen structures consist of two parts (rims). The
upper rim (head) of the macrocycle comprises of the cyclohexane
rings, aromatic carbon atoms with attached imine bonds and hydro-
xyl substituents. The lower rim (tail) is formed by the rest of the aro-
matic rings including substituents at the C-5 aromatic carbon atoms.
The molecular and supramolecular structures of calixsalens are
determined by the size and electronic properties of the substituents
at the C-5 positions. Small substituents or polar groups, such as halo-
gens, allow the formation of tail-to-tail dimers that mutually inter-
penetrate into their corresponding cavities (Fig. 1a). Bulky,
hydrophobic substituents reverse the conformation of the macrocy-
cle and prevent tail-to-tail assembly. These macrocycles mostly
aggregate in crystals to form head-to-head capsules with internal
voids capable of solvent inclusion (see Fig. 1b).12
hexaimine macrocycle (trianglimine) as the sole product.3 This
method soon received wide attention and opened up new possibil-
ities for the synthesis of macrocyclic compounds from relatively
simple building blocks. These cyclocondensation reactions are rel-
atively non-sensitive to solvent polarity and substrate concentra-
tion, while the shape and stoichiometry of the final product is
determined by the structure of the aromatic linker.4 The use of chi-
ral dialdehydes or diamine substrates with multiple stereogenic
centers showed match/mismatch effects that may favor or prevent
macrocyclization in the absence of a template.5–9
In general, cyclocondensation of 1 with linear 1,4-dialdehydes
(such as terepthalaldehyde) provided the [3+3] products, whereas
Recently we have shown that the reaction between rac-1 and
various C-5 substituted dialdehydes 2 is highly stereoselective
⇑
Corresponding author.
E-mail address: marcin.kwit@amu.edu.pl (M. Kwit).
http://dx.doi.org/10.1016/j.tetasy.2017.08.021
0957-4166/Ó 2017 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

2
M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
R
N
R
N
OH
N
R
R
N
N
solvent, Ar,
RT, 24-48 h
NH2
NH2
HO
+
OH
OHC
CHO
N
OH
1
2a-2d
3a-3d
a
c
b
d
O
NH
O
NH
R =
O
NH
O
NH
Scheme 1. Synthesis of calixsalens 3 from (R,R)-1 and C5-substituted 2-hydroxyisophthalaldehydes 2.
In continuation of our interests in template-free synthesis and
supramolecular properties of chiral macrocycles and molecular
cages, we decided to expand on our studies on calixsalens bearing
additional chiral secondary amide substituents at the C-5 position.
Two chiral zones can be distinguished in these structures (see
Fig. 2). The first one is related to the chirality of the parent diamine
and can be treated as a macrocycle base. The second chiral zone
will be placed in the ‘tail part’ of the molecule and associated with
the presence of the chiral substituent. Thus, such macrocycles can
be named as ‘double chiral’. The introduction of an additional chi-
ral fragment in the macrocycle skeleton will not only influence the
molecular structure. The use of common supramolecular synthon,
namely the NAHꢀ ꢀ ꢀO@C amideꢀ ꢀ ꢀamide hydrogen bonds, may lead
to the generation of various structural networks and consequently
lead to the formation of a new type of calixsalen associates in the
solid state, impossible to achieve with the hitherto known cal-
ixsalen molecules.
Figure 1. Schematic representation of possible types of host packing in calixsalen
crystals: (a) tail-to-tail (host–guest) dimer; (b) head-to-head dimer (capsule). Red
balls represent hydroxyl groups; green balls represent substituents at C-5 positions
of aromatic rings.
2. Results and discussion
and leads to homochiral all-R and all-S calixsalens. This chiral self
sorting is also visible in the solid state, since macrocycles dimerize
in homochiral tail-to-tail dimers and further aggregate in a hete-
rochiral head-to-head manner.13,14
2.1. Synthesis and structure of ‘double chiral’ calixsalens
While 1 can be easily obtained in both enantiomeric forms, to
date chiral derivatives of 2 are not known. Our initial attempts to
second chiral zone
(in the tail of the molecule)
NH
O
HN
O
HN
secondary
amide
O
functionalities
intra- and intermolecular
hydrogen
aromatic hydrophobic
linkers
••• interaction possible)
(π
π
bonding pattern
possible
N
N
N
OH
N
HO
first chiral zone
(macrocycle basement)
N
HO
N
Figure 2. Design concept underlying ‘double chiral’ calixsalens.
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
CONHR*
3
COOH
Br
1) SOCl2, Δ
4a 4d,
2) amine
-
Et3N, CH2Cl2,
RT
Br
5a 5d
-
1) n-BuLi, THF, -78 °C
2) B(OMe)3, THF,
-78 °C → RT
Br
3) H2O, HCl
CONHR*
OHC
CHO
OH
2a-2d
Suzuki
coupling
B(OH)2
Figure 3. Parts of the 1H NMR spectra of calixsalen 3a (a) crude product; (b)
product after crystallization. Arrows indicate signals correspond to expanded [4+4]
macrocycle3a0.
6a-6d
4a
5a
5b
6a
6b
2a
= (R)-H3CCH(NH2)Ph →
= (S)-H3CCH(NH2)Ph →
→
→
→
→
4b
2b
4c = (R)-H3CCH(NH2)Cy → 5c → 6c → 2c
4d = (S)-H3CCH(NH2)Cy → 5d → 6d → 2d
corresponding to the expanded [4+4] macrocycles 3a0–3d0. This is
rather unexpected due to the strong preference to form [3+3]
cyclocondensation products in reactions between 2-hydroxyisoph-
thalaldehyde derivatives and rigid diamines. On the other hand,
the formation of both contracted and expanded macrocycles in
addition to the expected [3+3] product in reactions between 2,6-
diformylpiridine and (R,R)-1 has been reported.16
In contrast to simple calixsalens, in the mass spectra of 3a–3d
we did not detect any peaks that correspond to the aggregates of
the respective macrocycles.17 This suggested the lack of inter-
molecular interactions between macrocycles in the gas phase.
Since the chromatographic separation of the products is not possi-
ble, the relative proportions of ‘normal’ [3+3] and ‘expanded’ [4+4]
macrocycles were estimated based on integration of respective
peaks in 1H NMR spectra. The proportions of 3a–3d to its expanded
congeners 3a0–3d0 varied from 4:1 for 3a–3c to 6.6:1 for 3d.
The characteristic features observed in 1H NMR spectra of 3a-3d
were slightly different in chemical shifts of diagnostic methine
protons at the stereogenic centers. For example, the chemical shift
of PhCHN proton found for 3a was 5.24 ppm, whereas for its
diastereoisomer 3b, it was only slightly shifted downfield
(5.25 ppm). For 3c and 3d the difference in chemical shift was
slightly higher, ca 0.03 ppm. The multiplets characteristic for
CHN protons in cyclohexane rings appeared at 3.32, 3.34, 3.43,
3.41 ppm, respectively for 3a–3d.
A similar situation occurred in the electronic circular dichroism
spectra of 3a–3d (see Fig. 4), which are dominated by the effects
originated from the macrocycle core. The negative Cotton effects
alternate with positive Cotton effects and a sequence of observed
Cotton effect ꢁ/+/ꢁ/+/ꢁ/+ was characterized for calixsalens and
originated from the negative helicity of NAC⁄AC⁄AN torsion angle
in the diaminocyclohexane moiety.12 Thus, neither the amine type
nor its absolute configuration has any effect on the observed UV
and ECD spectra. The addition of 10% v/v 1,1,1,3,3,3-hexafluoro-
2-propanol (HFIP) caused bathochromic shift and significant
enhancement of weak absorption band at ca. 350 nm, due to the
formation of stable keto-enamine form.11 The presence of ‘ex-
panded’ [4+4] macrocycles 3b0-3d0 (vide supra) in solution had a
negligible effect on the UV and ECD bands.
Despite many attempts, we were not able to separate both
macrocyclic forms, probably due to the similar solubilities of both
[3+3] and [4+4] macrocycles in the common organic solvents and/
or dynamic structure of the system. The macrocycle 3a is an excep-
tion; after repeated careful crystallizations, we obtained analyti-
cally pure crystals suitable for spectroscopic measurements and
Scheme 2. Synthesis of chiral dialdehydes 2a–2d via Suzuki coupling.
obtain chiral dialdehyde from tyrosine and related compounds
were unsuccessful. Recently, Mastalerz et al. reported the synthesis
of C-5 arylated derivatives of 2-hydroxyisophthalaldehyde, thus
we decided to introduce chiral substituent to 2-hydroxyisophtha-
laldehyde using Suzuki coupling between 5-bromo-2-hydroxy-
isophthalaldehyde and chiral boronic acid.15 The synthetic route
to chiral boronic acids and then to dialdehydes 2a–2d is shown
in Scheme 2.
We started with commercially available 4-bromobenzoic acid,
which was transferred to acid chloride and then reacted with pri-
mary amines 4a–4d to provide amides 5a–5d in almost quantita-
tive yields. Treatment of each secondary amide, with n-butyl
lithium and triethylborate, followed by hydrolysis, yielded after
careful crystallization of the crude product, the optically active
boronic acids 6a–6d as pairs of enantiomers, respectively 6a, 6b
and 6c, 6d. The Suzuki coupling between 5-bromo-2-hydroxy-
isophthalaldehyde and chiral boronic acids 6a–6d provide chiral
dialdehydes 2a–2d.
Macrocycles 3a–3d were obtained by the reaction of equimolar
amounts of (R,R)-1 (0.2 mmol) and respective amounts of aldehyde
2a–2d in 20 mL of dry dichloromethane for 24 h at room tempera-
ture. The same reactions were performed in ethanol or dimethyl-
sulfoxide (20 mL, 24 h). The polarity of solvent did not affect the
results and all of the above-mentioned approaches gave virtually
the relevant macrocycles as the main reaction products. We did
not observe any difference in reactivity between dialdehydes of
opposite absolute configurations at the stereogenic centers. The
chiral part in the dialdehyde is too far away from the newly formed
imine bonds and does not affect the reaction yield. Similarly we did
not observe any chiral sorting when equimolar amounts of dialde-
hydes (R)-2a and (S)-2d were reacted with (R,R)-1 under standard
conditions. Both 1H NMR and ESI MS spectra confirmed the forma-
tion of a statistical mixture of products differ in constitution and
molecular mass.
1H NMR spectra measured for crude products confirmed the for-
mation of the cyclic structures. We did not observe any signals
characteristic of the aldehyde, however next to the signals charac-
teristic for the [3+3] products we observed additional signals (see
Fig. 3). Measurements of the mass spectra confirmed the formation
of the [3+3] structure as the main product. However, in the mass
spectra there were second molecular peaks of the molecular mass
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

4
M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
Figure 4. UV (upper panels) and ECD spectra (lower panels) measured for pairs of diastereoisomers 3a, 3b (left) and 3c, 3d (right) in dichloromethane (black and blue lines)
and in dichloromethane containing 10% v/v 1,1,1,3,3,3-hexafluoro-2-propanol (black and blue dashed lines).
X-ray diffraction study. In the case of 3c, we obtained very small
amounts of crystalline material suitable for X-ray diffraction anal-
ysis, but not enough for full spectroscopic characterization.
Thus, for further structural study, we chose calixsalen 3a as the
representative example. To shed light on the molecular structure of
the compound, we performed theoretical analysis. The calculation
protocol included conformational search at the molecular mechan-
ics level,18 pre-optimization of all minima found at the MM level
with the use of PM6 Hamiltonian and full optimization at the
M06L/6-31G(d) level the pre-optimized structures.19 It is notewor-
thy that the number of low-energy structures that may participate
in a conformational equilibrium is relatively low and in the case of
3a does not exceeded 8. These structures differ in the mutual ori-
entation of CH3(CH)Ph parts within the same molecule and the
possibility to form intramolecular hydrogen bonding network. In
each calculated structure the additional chiral substituents in tail
Figure 5. Calculated at the M06L/6-31G(d) level structures of calixsalen 3a (a) the
lowest-energy conformer, (b) C3-symmetrical conformer. Dashed lines indicate
possible attractive interactions.
of the molecule, form an umbrella over macrocycle cavity and do
not for the allow formation of tail-to-tail dimers typical for known
calixsalens.
The structure of the lowest energy conformer of 3a, optimized
at the DFT level, is shown in Figure 5a. Due to the highly symmet-
rical structure of the calixsalen skeleton, we expected a C3-sym-
metric structure for macrocycle 3a. However, none of the
energetically preferred structures were symmetrical. The lowest
energy C1-symmetrical conformation of 3a is stabilized by the for-
mation of hydrogen bonding array involving two neighboring
amide hydrogen atoms and one carbonyl group. The remaining
one amide proton and the two C@O groups are placed outside
the macrocycle cavity to give a chance for the formation of hydro-
gen bonding network in the solid state. The calculated NAHꢀ ꢀ ꢀO@C
distances are 1.83 and 1.99 Å. For the sake of comparison, Figure 5b
shows the C3-symmetrical conformer of 3a. This particular confor-
mation is characterized by the cascade of intramolecular
NHꢀ ꢀ ꢀO@C P-helical H-bond array and by the significant non-pla-
narity of the amide moiety (the torsion angle HANAC@O is
157°). The formation of hydrogen bonding does not compensate
for the increase of energy due to the steric repulsion between
methyl groups. The energy difference between the lowest energy
conformer and the C3 symmetrical conformer is over 10 kcal molꢁ1
.
On the other hand, in the 1H NMR spectra we observed averaged
signals, the numbers of which confirmed the symmetry of the
molecule.
2.2. Crystal structure of 3a and 3c
Calixsalen 3a crystallizes in the monoclinic system with the
space group C2. The asymmetric unit is comprised of one molecule
of 3a, one molecule of acetonitrile (MeCN) and three molecules of
dichloromethane (DCM). MeCN is located in the cavity of 3a, one
DCM is located slightly above the upper rim while the two other
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
5
Figure 6. A van der Waals representation of the calixsalen molecules investigated: a top (above) and side (below) views of 3a (a) and 3c (b).
DCM molecules are located in the interstitial spaces. Due to the
high disorder of the remaining solvent molecules and the problem-
atic modeling, their contributions were removed from the diffrac-
tion data using the PLATON/SQUEEZE procedure.20 The same
SQUEEZE procedure was used for the solvent molecules in the crys-
tals of 3c since we were unable to identify the solvent molecules
(DCM or MeCN) or their positions. Therefore, the asymmetric unit
of 3c, which crystallizes in orthorhombic space group P212121, con-
sists of one molecule of calixsalen and no solvent (after applying
SQUEEZE). The stereogenic centers of the first and second chiral
zones in 3a and 3c have the same absolute configuration, i.e., all
are (R). In 3a the refined Flack parameter (x) and its standard
uncertainty is sufficiently small (0.040(7)), clearly indicating that
the assumed absolute structure is correct21 while in 3c this value
is meaningless (0.2(2)). Thus, the absolute structure of the investi-
gated crystal is assumed from the known absolute configuration of
the (R,R)-1,2-diaminocyclohexane that was used as starting mate-
rial in the syntheses.
Calixsalens 3a and 3c formally have C3 symmetry, however they
remain asymmetric in the solid state. Common features observed
in the solid-state structures of 3a and 3c are its trans conformation
of the ACONHA groups (176, 176 and ꢁ179° in 3a and 168, ꢁ178
and 179° in 3c) and the presence of intramolecular OAHꢀ ꢀ ꢀN
hydrogen bonds within the upper rim, which stabilize the upper
rim (the Hꢀ ꢀ ꢀO distances ranging from 1.82 to 1.89 Å in 3a and from
1.80 to 1.82 Å in 3c). Calixsalens 3a and 3c differ in the modifica-
tion of their second chiral zones: in 3a there is aromatic six-mem-
bered ring attached to the stereogenic center while in 3c there is an
aliphatic six-membered ring. Such small changes in the character
of the ring introduce significant conformation differences in both
macrocycles. In particular, these conformational differences reflect
in the mutual orientation of two phenyl rings of one linker as well
as the mutual orientation of all three chiral C-5 substituents. The
rotation of two phenyl rings is defined by the C2sp–C2sp–Cs2p–Cs2p tor-
sion angle. This parameter exhibits considerable variation in each
of the macrocycles. In 3a two pairs of the phenyl rings are twisted
by approximately ꢁ22.2(5) and ꢁ36.1(5)° in the same direction
taking into account the sign of the torsion angle measured, while
the third pair of rings is twisted by 38.0(5)° in the opposite direc-
tion. In addition, two neighboring substituents of the same mole-
cule are located relatively close to the other, promoting the
formation of NAHꢀ ꢀ ꢀO intramolecular hydrogen bonds in which
the amide groups are involved [Hꢀ ꢀ ꢀO 2.08 Å, Nꢀ ꢀ ꢀO 2.918(4) Å,
N–Hꢀ ꢀ ꢀO 160°]. Two terminal phenyl rings of the second chiral
zone are directed towards the macrocyclic cavity and thus obscure
its entrance. The third terminal phenyl ring is directed to the out-
side of the macrocycle and is involved in CAHꢀ ꢀ ꢀ
p intermolecular
interactions with the cyclohexane unit of a neighboring molecule.
Unlike in 3a, in 3c the three pairs of phenyl rings are twisted in the
same direction displaying an M-helical array [ꢁ28(1), ꢁ32(1) and
ꢁ46(1)°] and all three chiral C-5 substituents are embedded more
symmetrically within the lower rim preventing the formation of
intramolecular interactions between their amide groups. These
amide groups are only involved in intermolecular interactions.
The terminal cyclohexane rings are positioned outwardly on the
macrocycle making the inner cavity fully open. The van der Waals
representation of the molecular shapes of 3a and 3c are shown in
Figure 6.
The differences in the ring of the second chiral zone of 3a and 3c
also introduce differences in the self-assembled solid-state. In 3a,
two symmetry-related molecules are mutually offset such that
the cyclohexane ring of one molecule is located near the entrance
of the cavity of a neighboring molecule (see Fig. 7a). A similar
arrangement of the macrocycles was previously observed in the
crystals of a calixsalen with trityl substituents.12 Moreover in the
crystal of 3a, two neighboring molecules are oriented in an
antiparallel fashion form dimer stabilized by multiple intermolec-
ular CAHꢀ ꢀ ꢀ
p
and
pꢀ ꢀ ꢀp interactions, as it shown in Figure 7b. The
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

6
M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
Figure 7. Mutual arrangement of two neighboring macrocycles in the crystals of 3a: Offset arrangement (a) and dimeric arrangement (b). Dashed lines indicate
intermolecular CAHꢀ ꢀ ꢀ and ꢀ ꢀ ꢀ interactions.
p
p p
Figure 8. (a) Mutual insertion of two neighboring molecules that leads to the formation of intermolecular NAHꢀ ꢀ ꢀO hydrogen bonding, (b) the hydrogen bonding chain
running along the b lattice direction. Dashed lines indicate NAHꢀ ꢀ ꢀO hydrogen bonds interactions.
solid state structure of 3c gives rise to a novel type of supramolec-
ular architecture that has not previously been observed. In the
crystal, two neighboring macrocycles are partially interdigitated,
i.e., one macrocycle insert one of the linker in between two other
linkers of adjacent macrocycle, as shown in Figure 8a. Their mutual
arrangement leads to the formation of infinite 1D chains of
NAHꢀ ꢀ ꢀO hydrogen bonds that are propagated along the b direction
(Hꢀ ꢀ ꢀO 2.25 and 2.17 Å, Nꢀ ꢀ ꢀO 2.968(10) and 3.005(8) Å, NAHꢀ ꢀ ꢀO
140 and 157°). The hydrogen bonding motif is described by the
graph set notation C11(4).
two neighboring amide hydrogen atoms and one carbonyl group.
The remaining hydrogen bond donors and acceptors may be
involved in intermolecular interactions. The formation of the
NAHꢀ ꢀ ꢀO@C amideꢀ ꢀ ꢀamide hydrogen bonds generate a new type
of structural network and consequently lead to the formation of
a new kind of calixsalen associates in the solid state.
The results reported here could be used for testing other com-
pounds, especially for isomer separation. Studies are currently in
progress in our laboratory and the results will be reported in due
course.
4. Experimental
4.1. General
3. Conclusions
In conclusion, we presented an alternative way for synthesis of
calixsalens characterized by the presence of additional chirality
elements attached to the macrocyclic skeleton. The additional chi-
ral fragments create the second chiral zone in the macrocycle
molecule. The calixsalens may be conveniently obtained from chi-
ral dialdehydes, which in turn can be synthesized from chiral boro-
nic acids and 5-bromo-2-hydroxyisophthalaldehyde through
Suzuki coupling.
The molecular and supramolecular structure of the macrocycle
is affected by the presence of secondary amides fragments in the
‘tail part’ of the molecule. The structure of the isolated molecule
is stabilized by intramolecular hydrogen bonding array involving
1H and 13C NMR spectra were recorded on a Bruker 400 MHz
or Bruker 300 MHz at ambient temperature. All 1H NMR spectra
are reported in parts per million (ppm) downfield of TMS and
were measured relative to the signals for CDCl3 (7.27 ppm). All
13C NMR spectra were reported in ppm relative to residual
CDCl3 (77.0 ppm) and were obtained with 1H decoupling. Mass
spectra were recorded on AB Sciex TripleTOFÒ 5600+System
and Bruker UltrafleXtreme MALDI-TOF/TOF spectrometer with
DHB matrix. Melting points were measured using open glass
capillaries in a Büchi Melting Point B-545 apparatus. A Jasco
P-2000 polarimeter was used for optical rotation measurements
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
7
(at 20 °C). UV and CD spectra were recorded on a Jasco J-810
spectropolarimeter at room temperature in dichloromethane
and in 9:1 v/v mixture of dichloromethane and 1,1,1,3,3,3-hex-
afluoro-2-propanol (HFIP).
workup and crystallization 5c was obtained as a white solid
(1.9 g, 62%); mp 194–199 °C; HRMS (ESI) calcd for C15H20BrNO
[M+H]+ 310.0801; found 310.0816; 1H NMR (300 MHz, DMSO) d
8.19 (d, J = 8.5 Hz, 1H, ANH), 7.78 (d, J = 8.5 Hz, 2H, Ar), 7.65 (d,
J = 8.5 Hz, 2H, Ar), 3.93–3.65 (m, 1H, ACH), 1.78–1.50 (m, 5H, Cy),
1.50–1.29 (m, 1H, Cy), 1.23–1.10 (m, 3H, Cy), 1.09 (d, J = 6.7 Hz,
3H, ACH3), 1.00–0.83 (m, 2H, Cy); 13C NMR (75 MHz, DMSO) d
165.09 (ACO), 134.51 (Ar), 131.59 (Ar), 129.89 (Ar), 125.02 (Ar),
49.83 (ACH), 42.83 (Cy), 29.71 (Cy), 29.41 (Cy), 26.47 (Cy), 26.20
(Cy), 18.08 (ACH3); FTIR (ATR): ṽ = 3292, 2976, 2935, 2913, 2848,
4.2. General procedure for the synthesis of amides 5a–5d (A)
A mixture of 4-bromobenzoic acid (1 equiv) and thionyl chlo-
ride (10 equiv) was stirred at 79 °C for 5 h. After cooling to room
temperature, the excess of thionyl chloride was evaporated. The
crude acid chloride was diluted in dichloromethane and was added
slowly to cooled mixture of triethyl amine (2.5 equiv) and proper
amine 4a–4d (2 equiv) in dry dichloromethane. The mixture was
stirred at room temperature overnight. The reaction was quenched
by the addition of 10% HCl. The organic layer was washed with
water, saturated sodium bicarbonate and brine and dried over Na2-
SO4. The solvent was evaporated under reduced pressure and the
white solid product was obtained. Purification by crystallization
from mixture of chloroform/cyclohexane gave the corresponding
amide 5a–5d.
1631, 1544 cmꢁ1; [
a]D = ꢁ28.6 (c 1, methanol).
4.2.4. (S)-4-Bromo-N-(1-cyclohexylethyl)benzamide 5d
According to A: 4-bromobenzoic acid (2 g, 10 mmol), thionyl
chloride (7.5 mL, 100 mmol) were stirred for 5 h at 79 °C. After
workup, the obtained acid chloride was diluted with 10 mL of
dichloromethane and added slowly to cooled to 0 °C mixture of tri-
ethyl amine (3.5 mL, 25 mmol) and (S)-cyclohexylethylamine 4d,
(3 mL, 20.2 mmol) in 30 mL of dichloromethane. After workup
and crystallization 5d was obtained as a white solid (2.1 g, 68%);
mp 195–199 °C; HRMS (ESI) calcd for
C
15H20BrNO [M+H]+
4.2.1. (R)-4-Bromo-N-(1-phenylethyl)benzamide 5a
310.0801; found 310.0816; 1H NMR (300 MHz, DMSO) d 8.19 (d,
J = 8.5 Hz, 1H, ANH), 7.78 (d, J = 8.5 Hz, 2H, Ar), 7.65 (d, J = 8.5 Hz,
2H, Ar), 3.93–3.65 (m, 1H, ACH), 1.78–1.50 (m, 5H, Cy), 1.50–1.29
(m, 1H, Cy), 1.23–1.10 (m, 3H, Cy), 1.09 (d, J = 6.7 Hz, 3H, ACH3),
1.00–0.83 (m, 2H, Cy); 13C NMR (75 MHz, DMSO) d 165.09 (ACO),
134.51 (Ar), 131.59 (Ar), 129.89 (Ar), 125.02 (Ar), 49.83 (ACH),
42.83 (Cy), 29.71 (Cy), 29.41 (Cy), 26.47 (Cy), 26.20 (Cy), 18.08
(ACH3); FTIR (ATR): ṽ = 3292, 2976, 2935, 2913, 2848, 1631,
According to A: 4-bromobenzoic acid (3.5 g, 17.4 mmol), thionyl
chloride (13 mL, 174 mmol) were stirred for 5 h at 79 °C. After
workup, the obtained acid chloride was diluted with 10 mL of
dichloromethane and added slowly to cooled to 0 °C mixture of tri-
ethyl amine (6 mL, 43.2 mmol) and (R)-phenylethylamine (4a,
4.5 mL, 35.4 mmol) in 30 mL of dichloromethane. After workup
and crystallization 5a was obtained as a white solid (3.4 g, 64%);
mp 163–166 °C; HRMS (ESI) calcd for
C
15H14BrNO [M+H]+
1544 cmꢁ1; [
a]D = +28.6 (c 1, methanol).
304.0332; found 304.0351; 1H NMR (300 MHz, DMSO) d 8.89 (d,
J = 8.0 Hz, 1H, ANH), 7.84 (d, J = 8.6 Hz, 2H, Ar), 7.68 (d, J = 8.6 Hz,
2H, Ar), 7.43–7.26 (m, 4H, Ar0), 7.26–7.18 (m, 1H, Ar0), 5.16 (p,
J = 7.2 Hz, 1H, ACH), 1.48 (d, J = 7.1 Hz, 3H, ACH3); 13C NMR
(75 MHz, DMSO) d 165.04 (ACO), 145.20 (Ar), 134.08 (Ar), 131.70
(Ar), 130.00 (Ar), 128.71 (Ar), 127.10 (Ar), 126.51 (Ar), 125.35
(Ar), 49.03 (ACH), 22.66 (ACH3); FTIR (ATR): ṽ = 3343, 3030,
2975, 2928, 1637, 1586, 1526, 1480, 1444, 1267, 1073, 1012,
4.3. General procedure for the synthesis of boronic acids 6a–6d
(B)
Amide 5a–5d (1 equiv) was dissolved in dry THF and the mix-
ture was cooled to ꢁ78 °C under an argon atmosphere. 1.6 M n-
butyllithium solution (2.28 equiv) was slowly added and the mix-
ture was stirred for 30 min at ꢁ78 °C. An excess of triethyl borate
was added and the mixture was slowly warmed to 0 °C after which
2 M HCl was added. The mixture was stirred at room temperature
overnight and then was extracted three times with ethyl acetate.
The organic layer was washed with brine and dried over Na2SO4.
The solvent was evaporated under vacuum and the white solid
product was obtained. Purification by crystallization from mixture
of ethyl acetate/cyclohexane gave the boronic acid.
841, 756, 699 cmꢁ1; [
a]
D = ꢁ40.2 (c 1, methanol).
4.2.2. (S)-4-Bromo-N-(1-phenylethyl)benzamide 5b
According to A: 4-bromobenzoic acid (3.5 g, 17.4 mmol), thionyl
chloride (13 mL, 174 mmol) were stirred for 5 h at 79 °C. After
workup, the obtained acid chloride was diluted with 10 mL of
dichloromethane and added slowly to cooled to 0 °C mixture of tri-
ethyl amine (6 mL, 43.2 mmol) and (S)-phenylethylamine 4b
(4.5 mL, 34.9 mmol) in 30 mL of dry dichloromethane. After
workup and crystallization 5b was obtained as a white solid
(3.6 g, 68%); mp 163–166 °C; HRMS (ESI) calcd for C15H14BrNO
[M+H]+ 304.0332; found 304.0351; 1H NMR (300 MHz, DMSO) d
8.89 (d, J = 8.0 Hz, 1H, ANH), 7.84 (d, J = 8.6 Hz, 2H, Ar), 7.68 (d,
J = 8.6 Hz, 2H, Ar), 7.43–7.26 (m, 4H, Ar0), 7.26–7.18 (m, 1H, Ar0),
5.16 (p, J = 7.2 Hz, 1H, ACH), 1.48 (d, J = 7.1 Hz, 3H, ACH3); 13C
NMR (75 MHz, DMSO) d 165.04 (ACO), 145.20 (Ar), 134.08 (Ar),
131.70 (Ar), 130.00 (Ar), 128.71 (Ar), 127.10 (Ar), 126.51 (Ar),
125.35 (Ar), 49.03 (ACH), 22.66 (ACH3); FTIR (ATR): ṽ = 3343,
3030, 2975, 2928, 1637, 1586, 1526, 1480, 1444, 1267, 1073,
4.3.1. (R)-(4-((1-Phenylethyl)carbamoyl)phenyl)boronic acid 6a
According to B: To cooled to ꢁ78 °C solution of amide 5a
(3.04 g, 10 mmol) in 150 mL of THF 1.6 M n-butyllithium solution
(16 mL, 22.8 mmol) was added. After 30 min, triethyl borate
(5 mL, 28.9 mmol) was added. After workup and crystallization
6a was obtained as a white solid (1.16 g, 43%); mp 215–217 °C;
HRMS (ESI) calcd for
C
15H16BNO3 [M+H]+ 270.1296; found
270.1303; 1H NMR (300 MHz, DMSO) d 8.80 (d, J = 8.0 Hz, 1H,
ANH), 8.20 (s, 2H, AB(OH)2), 7.91–7.81 (m, 4H, Ar), 7.43–7.18 (m,
5H, Ar0), 5.18 (p, J = 7.0 Hz, 1H, ACH), 1.48 (d, J = 7.1 Hz, 3H,
ACH3); 13C NMR (75 MHz, DMSO) d 166.12 (ACO), 145.40 (Ar),
136.27 (Ar), 134.34 (Ar), 128.69 (Ar), 127.04 (Ar), 126.72 (Ar),
126.53 (Ar), 48.88 (ACH), 22.72 (ACH3); FTIR (ATR): ṽ = 3303,
3062, 2977, 2933, 1631, 1526, 1494, 1401, 1332, 1149, 1015,
1012, 841, 756, 699 cmꢁ1; [
a]D = +40.2 (c 1, methanol).
4.2.3. (R)-4-Bromo-N-(1-cyclohexylethyl)benzamide 5c
According to A: 4-bromobenzoic acid (2 g, 10 mmol), thionyl
chloride (7.5 mL, 100 mmol) were stirred for 5 h at 79 °C. After
workup, the obtained acid chloride was diluted with 10 mL of
dry dichloromethane and added slowly to cooled to 0 °C mixture
of triethyl amine (3.5 mL, 25 mmol) and (R)-cyclohexylethylamine
4c (3 mL, 20.5 mmol) in 30 mL of dry dichloromethane. After
696 cmꢁ1; [
a
]D = ꢁ36.4 (c 1, methanol).
4.3.2. (S)-(4-((1-Phenylethyl)carbamoyl)phenyl)boronic acid 6b
According to B: To cooled to ꢁ78 °C solution of amide 5b
(3.04 g, 10 mmol) in 160 mL of THF 1.6 M n-butyllithium solution
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

8
M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
(16 mL, 22.8 mmol) was added. After 30 min, triethyl borate (5 mL,
28.9 mmol) was added. After workup and crystallization, 6b was
obtained as a white solid (1.27 g, 47%); mp 215–217 °C; HRMS
(ESI) calcd for C15H16BNO3 [M+H]+ 270.1296; found 270.1306; 1H
NMR (300 MHz, DMSO) d 8.80 (d, J = 8.0 Hz, 1H, ANH), 8.20 (s,
2H, AB(OH)2), 7.91–7.81 (m, 4H, Ar), 7.43–7.18 (m, 5H, Ar0), 5.18
(p, J = 7.0 Hz, 1H, ACH), 1.48 (d, J = 7.1 Hz, 3H, ACH3); 13C NMR
(75 MHz, DMSO) d 166.12 (ACO), 145.40 (Ar), 136.27 (Ar), 134.34
(Ar), 128.69 (Ar), 127.04 (Ar), 126.72 (Ar), 126.53 (Ar), 48.88
(ACH), 22.72 (ACH3); FTIR (ATR): ṽ = 3303, 3062, 2977, 2933,
4.4.1. (R)-30,50-Diformyl-40-hydroxy-N-(1-phenylethyl)-[1,10-
biphenyl]-4-carboxamide 2a
According to C: 4-bromo-2,6-diformylphenol (458 mg, 2 mmol),
6a (538 mg, 2 mmol), K2CO3 (828 mg, 6 mmol) and [Pd(PPh3)4]
(50 mg, 0.04 mmol) were stirred in degassed toluene (10 mL)
under an argon atmosphere for 15 min at room temperature. Next,
a 1:1 mixture of degassed EtOH/H2O (10 mL) was added and mix-
ture was stirred for 16 h at 80 °C. After workup and purification, 2a
was obtained as a light yellow solid (165 mg, 22%); mp 179–
181 °C; HRMS (ESI) calcd for C23H19NO4 [MꢁH]ꢁ 372.1241; found
372.1232; 1H NMR (300 MHz, DMSO) d 11.67 (s, 1H, AOH), 10.33
(s, 2H, ACHO), 8.90 (d, J = 8.0 Hz, 1H, ANH), 8.41 (s, 2H, Ar00), 8.04
(d, J = 8.3 Hz, 2H, Ar), 7.84 (d, J = 8.3 Hz, 2H, Ar), 7.45–7.19 (m,
5H, Ar0), 5.21 (p, J = 7.1 Hz, 1H, ACH), 1.51 (d, J = 7.1 Hz, 3H,
ACH3); 13C NMR (75 MHz, DMSO) d 192.80 (ACHO), 165.45
(ACO), 162.20 (ACOH), 145.37 (Ar), 140.52 (Ar), 135.58 (Ar),
134.05 (Ar), 131.40 (Ar), 128.74 (Ar), 128.71 (Ar), 127.06 (Ar),
126.54 (Ar), 126.46 (Ar), 124.42 (Ar), 48.96 (ACH), 22.69 (ACH3);
FTIR (ATR): ṽ = 3337, 3061, 2973, 2885, 1686, 1660, 1634, 1600,
1631, 1526, 1494, 1401, 1332, 1149, 1015, 696 cmꢁ1; [
a]D = +36.4
(c 1, methanol).
4.3.3. (R)-(4-((1-Cyclohexylethyl)carbamoyl)phenyl)boronic
acid 6c
According to B: To cooled to ꢁ78 °C solution of amide 5c (2.5 g,
8.08 mmol) in 100 mL of THF 1.6 M n-butyllithium solution
(13 mL, 20.08 mmol) was added. After 30 min, triethyl borate
(5 mL, 28.9 mmol) was added. After workup and crystallization
6c was obtained as a white solid (1.48 g, 65%); mp 224–227 °C;
1532, 1450, 1319, 1271, 1232, 980, 848, 698 cmꢁ1; [
(c 1, methanol).
a]
D = ꢁ94.6
HRMS (ESI) calcd for
C
15H22BNO3 [M+H]+ 276.1766; found
276.1782; 1H NMR (300 MHz, DMSO) d 8.31–7.95 (s, 2H, AB
(OH)2), 8.08 (d, J = 8.6 Hz, 1H, ANH), 7.82 (dd, J = 19.1, 8.1 Hz, 4H,
Ar), 3.94–3.75 (m, 1H, ACH), 1.70 (m, 5H, Cy), 1.50–1.31 (m, 1H,
Cy), 1.26–1.04 (m, 3H, Cy), 1.11 (d, J = 6.8 Hz, 3H, ACH3), 0.95 (m,
2H); 13C NMR (75 MHz, DMSO) d 166.21 (ACO), 136.72 (Ar),
134.25 (Ar), 126.57 (Ar), 49.66 (ACH), 42.87 (Cy), 29.75 (Cy),
29.46 (Cy), 26.50 (Cy), 26.23 (Cy), 18.13 (ACH3); FTIR (ATR):
ṽ = 3280, 2971, 2939, 2918, 2848, 1627, 1538, 1365, 1320, 1253,
4.4.2. (S)-30,50-Diformyl-40-hydroxy-N-(1-phenylethyl)-[1,10-
biphenyl]-4-carboxamide 2b
According to C: 4-bromo-2,6-diformylphenol (458 mg, 2 mmol),
6b (538 mg, 2 mmol), K2CO3 (828 mg, 6 mmol) and [Pd(PPh3)4]
(50 mg, 0.04 mmol) were stirred in degassed toluene (10 mL)
under an argon atmosphere for 15 min at room temperature. Next,
a 1:1 mixture of degassed EtOH/H2O (10 mL) was added and mix-
ture was stirred for 16 h at 80 °C. After workup and purification, 2b
was obtained as a light yellow solid (120 mg, 16%); mp 179–
181 °C; HRMS (ESI) calcd for C23H19NO4 [MꢁH]ꢁ 372.1241; found
372,1232; 1H NMR (300 MHz, DMSO) d 11.67 (s, 1H, AOH), 10.33
(s, 2H, ACHO), 8.90 (d, J = 8.0 Hz, 1H, ANH), 8.41 (s, 2H, Ar00), 8.04
(d, J = 8.3 Hz, 2H, Ar), 7.84 (d, J = 8.3 Hz, 2H, Ar), 7.45–7.19 (m,
5H, Ar0), 5.21 (p, J = 7.1 Hz, 1H, ACH), 1.51 (d, J = 7.1 Hz, 3H,
ACH3); 13C NMR (75 MHz, DMSO) d 192.80 (ACHO), 165.45
(ACO), 162.20 (ACOH), 145.37 (Ar), 140.52 (Ar), 135.58 (Ar),
134.05 (Ar), 131.40 (Ar), 128.74 (Ar), 128.71 (Ar), 127.06 (Ar),
126.54 (Ar), 126.46 (Ar), 124.42 (Ar), 48.96 (ACH), 22.69 (ACH3);
FTIR (ATR): ṽ = 3337, 3061, 2973, 2885, 1686, 1660, 1634, 1600,
1155, 1118, 1028, 1013, 808, 691 cmꢁ1
methanol).
;
[a
]D = ꢁ30.0 (c 1,
4.3.4. (S)-(4-((1-Cyclohexylethyl)carbamoyl)phenyl)boronic acid
6d
According to B: To cooled to ꢁ78 °C solution of amide 5d
(2.559 g, 8.25 mmol) in 100 mL of THF 1.6 M n-butyllithium solu-
tion (14.5 mL, 23.2 mmol) was added. After 30 min, triethyl borate
(5 mL, 28.9 mmol) was added. After workup and crystallization, 6d
was obtained as a white solid (1.43 g, 64%); mp 224–227 °C; HRMS
(ESI) calcd for C15H22BNO3 [M+H]+ 276.1766; found 276.1772; 1H
NMR (300 MHz, DMSO) d 8.31–7.95 (s, 2H, AB(OH)2), 8.08 (d,
J = 8.6 Hz, 1H, ANH), 7.82 (dd, J = 19.1, 8.1 Hz, 4H, Ar), 3.94–3.75
(m, 1H, ACH), 1.70 (m, 5H, Cy), 1.50–1.31 (m, 1H, Cy), 1.26–1.04
(m, 3H, Cy), 1.11 (d, J = 6.8 Hz, 3H, ACH3), 0.95 (m, 2H); 13C NMR
(75 MHz, DMSO) d 166.21 (ACO), 136.72 (Ar), 134.25 (Ar), 126.57
(Ar), 49.66 (ACH), 42.87 (Cy), 29.75 (Cy), 29.46 (Cy), 26.50 (Cy),
26.23 (Cy), 18.13 (ACH3); FTIR (ATR): ṽ = 3280, 2971, 2939, 2918,
2848, 1627, 1538, 1365, 1320, 1253, 1155, 1118, 1028, 1013,
1532, 1450, 1319, 1271, 1232, 980, 848, 698 cmꢁ1; [
1, methanol).
a]D = +94.6 (c
4.4.3. (R)-N-(1-Cyclohexylethyl)-30,50-diformyl-40-hydroxy-[1,10-
biphenyl]-4-carboxamide 2c
According to C: 4-bromo-2,6-diformylphenol (458 mg, 2 mmol),
6c (550 mg, 2 mmol), K2CO3 (828 mg, 6 mmol) and [Pd(PPh3)4]
(50 mg, 0.04 mmol) were stirred in degassed toluene (10 mL)
under an argon atmosphere for 15 min at room temperature. Next,
a 1:1 mixture of degassed EtOH/H2O (10 mL) was added and mix-
ture was stirred for 16 h at 80 °C. After workup and purification, 2c
was obtained as a light yellow solid (150 mg, 20%); mp 205–
207 °C; HRMS (ESI) calcd for C23H25NO4 [MꢁH]ꢁ 378.1711; found
378.1690; 1H NMR (300 MHz, DMSO) d 11.67 (s, 1H, AOH), 10.33
(s, 2H, ACHO), 8.40 (s, 2H, Ar0), 8.20 (d, J = 8.5 Hz, 1H, ANH), 7.98
(d, J = 8.2 Hz, 2H, Ar), 7.82 (d, J = 8.2 Hz, 2H, Ar), 3.97–3.77 (m,
1H, ACH), 1.83–1.53 (m, 5H, Cy), 1.53–1.35 (m, 1H, Cy), 1.27–
1.06 (m, 3H, Cy), 1.13 (d, J = 6.7 Hz, 2H, ACH3), 1.05–0.85 (m, 1H,
Cy); 13C NMR (75 MHz, DMSO) d 192.79 (ACHO), 165.49 (ACO),
162.18 (ACOH), 140.27 (Ar), 135.52 (Ar), 134.51 (Ar), 131.46 (Ar),
128.62 (Ar), 126.38 (Ar), 124.42 (Ar), 49.76 (ACH), 42.88 (Cy),
29.78 (Cy), 29.47 (Cy), 26.49 (Cy), 26.23 (Cy), 18.17 (ACH3); FTIR
(ATR): ṽ = 3327, 2975, 2928, 2850, 1686, 1662, 1632, 1610, 1534,
808, 691 cmꢁ1; [
a]D = +30.0 (c 1, methanol).
4.4. General procedure for the synthesis of aldehydes 2a–2d (C)
4-Bromo-2,6-diformylphenol (1 equiv), boronic acid 6a–6d
(1 equiv), K2CO3 (3 equiv) and [Pd(PPh3)4] 2 mol % were stirred in
degassed toluene under an argon atmosphere for 15 min at room
temperature. Next, 1:1 (v/v) mixture of degassed EtOH/H2O was
added and mixture was stirred for 16 h at 80 °C. After cooling to
room temperature, the reaction was quenched by the addition of
concentrated HCl, followed by extraction with EtOAc (three times).
The organic extracts were washed with brine and dried over Na2-
SO4. The solvent was evaporated under vacuum and the yellow
solid product was obtained. Purification by column chromatogra-
phy on silica gel (2:3–hexane/ethyl acetate) and then crystalliza-
tion from dichloromethane/ethyl acetate gave the desired
aldehyde.
1446, 1383, 1320, 1285, 1272, 1237, 980, 848, 676 cmꢁ1
D = ꢁ38.5 (c 1, methanol).
;
[a]
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
9
4.4.4. (S)-N-(1-Cyclohexylethyl)-30,50-diformyl-40-hydroxy-[1,10-
biphenyl]-4-carboxamide 2d
4.5.2. 4,40,400-((2E,5E,11E,14E,17E)-12,72,132-Trihydroxy-
3,5,9,11,15,17-hexaaza-1,7,13(1,3)-tribenzena-4,10,16(1,2)-
tricyclohexanacyclooctadecaphane-2,5,8,11,14,17-hexaene-
15,75,135-triyl)tris(N-((S)-1-phenylethyl)benzamide)–
Calixsalen 4b
According to C: 4-bromo-2,6-diformylphenol (458 mg, 2 mmol),
6d (550 mg, 2 mmol), K2CO3 (828 mg, 6 mmol) and [Pd(PPh3)4]
(50 mg, 0.04 mmol) were stirred in degassed toluene (10 mL)
under an argon atmosphere for 15 min at room temperature. Next,
a 1:1 mixture of degassed EtOH/H2O (10 mL) was added and mix-
ture was stirred for 16 h at 80 °C. After workup and purification, 2d
was obtained as a light yellow solid (130 mg, 17%); mp 205–
207 °C; HRMS (ESI) calcd for C23H25NO4 [MꢁH]ꢁ 378.1711; found
378.1690; 1H NMR (300 MHz, DMSO) d 11.67 (s, 1H, AOH), 10.33
(s, 2H, ACHO), 8.40 (s, 2H, Ar0), 8.20 (d, J = 8.5 Hz, 1H, ANH), 7.98
(d, J = 8.2 Hz, 2H, Ar), 7.82 (d, J = 8.2 Hz, 2H, Ar), 3.97–3.77 (m,
1H, ACH), 1.83–1.53 (m, 5H, Cy), 1.53–1.35 (m, 1H, Cy), 1.27–
1.06 (m, 3H, Cy), 1.13 (d, J = 6.7 Hz, 2H, ACH3), 1.05–0.85 (m, 1H,
Cy); 13C NMR (75 MHz, DMSO) d 192.79 (ACHO), 165.49 (ACO),
162.18 (ACOH), 140.27 (Ar), 135.52 (Ar), 134.51 (Ar), 131.46 (Ar),
128.62 (Ar), 126.38 (Ar), 124.42 (Ar), 49.76 (ACH), 42.88 (Cy),
29.78 (Cy), 29.47 (Cy), 26.49 (Cy), 26.23 (Cy), 18.17 (ACH3); FTIR
(ATR): ṽ = 3327, 2975, 2928, 2850, 1686, 1662, 1632, 1610, 1534,
According to B: To trans-(1R,2R)-diaminocyclohexane (23 mg,
0.2 mmol) dissolved in 20 mL of methylene chloride dialdehyde
3b (75 mg, 0.2 mmol) was added in one portion. The resulting mix-
ture was stirred at room temperature for 24 h. The solvent was
evaporated under vacuum and the yellow solid product was
obtained. The [3+3] and [4+4] products were obtained with yields
80% an 20% respectively. HRMS (ESI) calcd for [3+3] C87H87N9O6 [M
+H]+ 1354.6852; found 1354.6842, for [4+4] C116H116N12O8 [M+H]+
1806.9145; found 1806.9176; mp >300 °C (dec.); 1H NMR
(300 MHz, CDCl3, asterisk indicate signals originated from [4+4]
macrocycle) d 14.36 (s, 1H, AOH), 13.86⁄, 8.68 (s, 1H, AN@CHA),
8.62⁄, 8.41⁄, 8.28 (s, 1H, AN@CHA), 8.12⁄, 8.02 (s, 1H, Ar), 7.95⁄,
7.84⁄, 7.72 (d, J = 7.9 Hz, 2H, Ar), 7.66⁄, 7.44–7.42 (m, 2H, Ar),
7.38–7.34 (m, 3H, Ar), 7.34–7.30 (m, 2H, Ar), 7.27–7.25 (m, 1H,
Ar), 7.10⁄, 6.92 (d, J = 7.3 Hz, 1H, ANH), 5.39–5.33 (m, 1H, ACH),
3.51–3.45 (m, 1H, ACHN@), 3.42–3.38⁄, 3.36–3.30 (m, 1H,
ACHN@), 3.24–3.18⁄, 2.00–1.70 (m, 6H, Cy), 1.67 (d, J = 6.8 Hz,
2H, ACH3), 1.53–1.48 (m, 2H, Cy).13C NMR (151 MHz, CDCl3) d
166.54 (AC@O), 164.00 (AN@CHA), 162.50 (AN@CHA), 156.43
(CAOH), 143.48 (Ar), 142.84 (Ar), 132.69 (s), 132.07 (Ar), 129.32
(Ar), 128.69 (Ar), 127.63 (Ar), 127.31 (Ar), 126.28 (Ar), 126.22
(Ar), 124.32 (Ar), 118.85 (Ar), 75.03 (ACHN@), 72.96 (ACHN@),
49.31 (ACH), 33.04 (Cy), 32.80 (Cy), 24.39 (Cy), 24.29 (Cy), 21.90
(ACH3) ppm; FTIR (ATR): ṽ = 3301, 3029, 2929, 2857, 1632, 1607,
1534, 1494, 1450, 1376, 1263, 1208, 1143, 1095, 1008, 850,
1446, 1383, 1320, 1285, 1272, 1237, 980, 848, 676 cmꢁ1; [
a] =
D
+38.5 (c 1, methanol).
4.5. General procedure for the synthesis of calixsalens 3a–3d (D)
To trans-(1R,2R)-diaminocyclohexane (R,R)-1 (1 equiv) dis-
solved in dry dichloromethane, dialdehyde 2 (1 equiv) was added
in one portion. The resulting mixture was stirred at room temper-
ature for 24 h in argon atmosphere. The solvent was evaporated
under vacuum and the yellow solid product was obtained.
737 cmꢁ1
.
4.5.3. 4,40,400-((2E,5E,11E,14E,17E)-12,72,132-Trihydroxy-
3,5,9,11,15,17-hexaaza-1,7,13(1,3)-tribenzena-4,10,16(1,2)-
tricyclohexanacyclooctadecaphane-2,5,8,11,14,17-hexaene-
15,75,135-triyl)tris(N-((R)-1-cyclohexylethyl)benzamide)–
Calixsalen 4c
A: According to B: To trans-(1R,2R)-diaminocyclohexane
(23 mg, 0.2 mmol) dissolved in 20 mL of methylene chloride
dialdehyde 3c (76.5 mg, 0.2 mmol) was added in one portion. The
resulting mixture was stirred at room temperature for 24 h. The
solvent was evaporated under vacuum and the yellow solid pro-
duct was obtained. [3+3] and [4+4] products were obtained with
yields 80% and 20% respectively. HRMS (ESI) calcd for [3+3]
4.5.1. 4,40,400-((2E,5E,11E,14E,17E)-12,72,132-Trihydroxy-
3,5,9,11,15,17-hexaaza-1,7,13(1,3)-tribenzena-4,10,16(1,2)-
tricyclohexanacyclooctadecaphane-2,5,8,11,14,17-hexaene-
15,75,135-triyl)tris(N-((R)-1-phenylethyl)benzamide)–
Calixsalen 4a
According to D: To trans-(1R,2R)-diaminocyclohexane (23 mg,
0.2 mmol) dissolved in 20 mL of methylene chloride, dialdehyde
3a (75 mg, 0.2 mmol) was added in one portion. The resulting mix-
ture was stirred at room temperature for 24 h. The solvent was
evaporated under vacuum and the yellow solid product was
obtained. [3+3] and [4+4] products were obtained with yield 83%
and 17% respectively. The [3+3] product 3a was purified by
repeated crystallization from dichloromethane/acetonitrile solu-
tion. HRMS (ESI) calcd for C87H87N9O6 [M+H]+1354.6852; found
1354.6841; mp >300 °C (dec.); 1H NMR (300 MHz, CDCl3) d 14.37
(s, 1H, AOH), 8.71 (s, 1H, AN@CHA), 8.28 (s, 1H, AN@CHA), 8.04
(s, 1H, Ar), 7.74 (d, J = 8.1 Hz, 2H, Ar), 7.41–7.33 (m, 6H, Ar,),
7.29–7.26 (m, 2H, Ar), 6.75 (d, J = 7.7 Hz, 1H, ANH), 5.35 (p,
J = 6.9 Hz, 1H, ACH), 3.52–3.42 (m, 1H, ACHN@), 3.41–3.29 (m,
1H, ACHN@), 1.98–1.71 (m, 6H, Cy), 1.65 (d, J = 6.9 Hz, 3H,
ACH3), 1.54–1.48 (m, 2H, Cy). 13C NMR (101 MHz, CDCl3) 13C
NMR (151 MHz, CDCl3) d 166.45 (AC@O), 163.80 (AN@CHA),
162.37 (AN@CHA), 156.15 (ACAOH), 143.35 (Ar), 143.03 (Ar),
132.68 (Ar), 132.15 (Ar), 129.46 (Ar), 128.71 (Ar), 128.22 (Ar),
127.54 (Ar), 127.36 (Ar), 126.40 (Ar), 126.28 (Ar), 124.32 (Ar),
118.98 (Ar), 75.16 (ACHN@), 73.03 (ACHN@), 49.37 (ACHA),
33.10 (Cy), 33.03 (Cy), 24.39 (Cy), 24.30 (Cy), 21.87 (ACH3) ppm;
FTIR (ATR): ṽ = 3312, 3029, 2930, 2858, 1633, 1607, 1533, 1501,
1448, 1375, 1344, 1290, 1263, 1206, 1143, 1097, 1006, 850,
C
C
87H105N9O6 [M+H]+ 1372.8261; found 1372.8290, for [4+4]
116H140N12O8 [M+H]+ 1831.1023; found 1831.1039; mp >300 °C
(dec.);1H NMR (300 MHz, CDCl3, asterisk indicate signals origi-
nated from [4+4] macrocycle) d 14.40 (s, 1H, AOH), 13.89⁄, 8.74
(s, 1H, AN@CHA), 8.64⁄, 8.32 (s, 1H, AN@CHA), 8.10 (s, 1H, Ar),
7.97⁄, 7.74 (d, J = 8.0 Hz, 2H, Ar), 7.67⁄, 7.43 (d, J = 7.9 Hz, 2H, Ar),
7.34 (s, 1H, Ar), 7.15⁄, 6.68⁄, 6.21 (d, J = 8.8 Hz, 1H, ANH), 4.19⁄,
4.09 (dq, J = 13.6, 6.7 Hz, 1H, ACH), 3.55–3.46 (m, 1H, ACHN@),
3.43–3.36 (m, 1H, ACHN@), 3.26⁄, 1.96–1.65 (m, 10H, Cy), 1.53–
1.45 (m, 2H, Cy), 1.23 (d, J = 6.7 Hz, 2H, ACH3), 1.32–1.00 (m, 6H,
Cy).13
C NMR (151 MHz, CDCl3) d 166.59 (AC@O), 163.74
(AN@CHA), 162.29 (AN@CHA), 156.08 (CAOH), 142.82 (Ar),
133.24 (Ar), 129.58 (Ar), 127.81 (Ar), 127.37 (Ar), 126.47 (Ar),
126.23 (Ar), 124.19 (Ar), 119.06 (Ar), 75.19 (ACHN@), 72.93
(ACHN@), 49.99 (ACH), 43.24 (Cy), 33.20 (Cy), 33.13 (Cy), 29.32
(Cy), 29.18 (Cy), 26.43 (Cy), 26.21 (Cy), 24.37 (Cy), 24.29 (Cy),
17.99 (ACH3) ppm; FTIR (ATR): ṽ = 3311, 3049, 2925, 2852, 1631,
1607, 1534, 1501, 1449, 1375, 1344, 1290, 1264, 1207, 1143,
735 cmꢁ1; [
a]
D = ꢁ306.1 (c 1, chloroform).
1097, 850, 735 cmꢁ1
.
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

10
M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
B: To trans-(1R,2R)-diaminocyclohexane (11 mg, 0.096 mmol)
methane and acetonitrile. Intensity data collected for 3a and 3c
was measured on a SuperNova diffractometer equipped with Cu
microfocus source (k = 1.54178 Å) and 135 mm Atlas CCD detector.
Data reduction and analysis for all of the crystals were carried out
with the CrysAlisPro program.22 In all experiments the sample
temperature (130K) was controlled with an Oxford Instruments
Cryosystem cold nitrogen-gas blower. The structures were solved
by direct methods using SIR-2011,23 and refined by the full-matrix
least-squares techniques with SHELXL-2014.24 All heavy atoms
were refined anisotropically. The hydrogen atoms bound to C
atoms were placed at calculated positions and refined using a rid-
ing model, and their isotropic displacement parameters were given
a value 20% higher than the isotropic equivalent for the atom to
which the H atoms were attached (for methyl hydrogen atoms this
value has been increased to 50%). The positions of the hydroxyl H
atoms were constrained to an ideal geometry [OH = 0.84 Å and
Uiso(H) = 1.2Ueq(O)] using the AFIX 147 command integrated in
SHELXL-2014.24 Graphical images were produced in Xseed25 using
Pov-Ray26 and Mercury27 programs.
dissolved in 20 mL of absolute ethanol dialdehyde 3c (36.6 mg,
0.096 mmol) was added in one portion. The resulting mixture
was stirred at room temperature for 24 h. The solvent was evapo-
rated under vacuum and the yellow solid product was obtained. [3
+3] and [4+4] products were obtained with yields 70% and 30%
respectively.
4.5.4. 4,40,400-((2E,5E,11E,14E,17E)-12,72,132-Trihydroxy-
3,5,9,11,15,17-hexaaza-1,7,13(1,3)-tribenzena-4,10,16(1,2)-
tricyclohexanacyclooctadecaphane-2,5,8,11,14,17-hexaene-
15,75,135-triyl)tris(N-((S)-1-cyclohexylethyl)benzamide)–
Calixsalen 4d
According to B: To trans-(1R,2R)-diaminocyclohexane (23 mg,
0.2 mmol) dissolved in 20 mL of methylene chloride dialdehyde
3d (76.5 mg, 0.2 mmol) was added in one portion. The resulting
mixture was stirred at room temperature for 24 h. The solvent
was evaporated under vacuum and the yellow solid product was
obtained. [3+3] and [4+4] products were obtained with yields
85% and 15% respectively. HRMS (ESI) calcd for [3+3]
C
C
87H105N9O6 [M+H]+ 1372.8261; found 1372.8264, for [4+4]
4.7. Crystal data for 3a
116H140N12O8 [M+H]+ 1831.1023; found 1831.1069; mp >300 °C
(dec.); 1H NMR (600 MHz, CDCl3, asterisk indicate signals origi-
nated from [4+4] macrocycle) d 14.37 (s, 1H, AOH), 13.89⁄, 8.71
(s, 1H, AN@CHA), 8.63⁄, 8.30 (s, 1H, AN@CHA), 8.13⁄, 8.06 (s,
1H, Ar), 7.95⁄, 7.72 (d, J = 7.9 Hz, 2H, Ar), 7.67⁄, 7.38 (d, J = 7.8 Hz,
2H, Ar), 7.30 (s, 1H, Ar), 7.12⁄, 6.36 (d, J = 8.7 Hz, 1H, ANH), 4.18–
4.13⁄, 4.10 (dd, J = 14.7, 6.9 Hz, 1H, ACH), 3.50 (s, 1H, ACHN@),
3.36 (s, 1H, ACHN@), 3.24⁄, 1.98–1.65 (m, 10H, Cy), 1.54–1,47 (m,
C
87H87N9O6*3(CH2Cl2)*C2H3N, Mr = 1650.48, 0.60 ꢂ 0.45 ꢂ
0.28 mm3, monoclinic, space group C2, a = 32.7041(8) Å,
b = 16.2508(2) Å, c = 22.2114(6) Å, b = 125.019(4)°, V = 9667.5(5)Å,
Z = 4,
Dx = 1.134 g/cm3,
F000 = 1592,
CuKa
radiation,
k = 1.54178 Å, T = 130(2)K, 2hmax = 152.8°, 40,128 reflections col-
lected, 19,441 unique (Rint = 0.031). Final GooF = 1.04, R1 = 0.062,
wR2 = 0.177, R indices based on 18,511 reflections with I > 2
r
(I)
2H, Cy), 1.23 (d, J = 6.7 Hz, 3H, ACH3), 1.32–1.03 (m, 6H, Cy);13
C
(refinement on F2), 1032 parameters, 1 restraint. Lp and absorption
NMR (151 MHz, CDCl3) d 166.71 (AC@O), 163.93 (AN@CHA),
162.40 (AN@CHA), 156.32 (CAOH), 142.66 (Ar), 133.27 (Ar),
132.19 (Ar), 129.48 (Ar), 127.46 (Ar), 126.31 (Ar), 124.21 (Ar),
118.94 (Ar), 75.09 (ACHN@), 72.96 (ACHN@), 49.99 (ACH), 43.31
(Cy), 33.07 (Cy), 32.96 (Cy), 29.33 (Cy), 29.27 (Cy), 26.45 (Cy),
26.25 (Cy), 26.23 (Cy), 24.38 (Cy), 24.30 (Cy), 17.99 (ACH3). FTIR
(ATR): ṽ = 3316, 2925, 2852, 1631, 1607, 1534, 1502, 1449, 1375,
corrections applied,
ter = 0.040 (7).28
l
= 2.04 mmꢁ1. Absolute structure parame-
Solvent contributions were removed from the diffraction data
using SQUEEZE. The estimated electron count in 3a is 393 in an
accessible void volume of 1482.8 Å3 and can indicate squeezing
of approximately eight molecules of dichloromethane per unit cell
(two per asymmetric unit).
1344, 1291, 1263, 1206, 1143, 1097, 1007, 850, 735 cmꢁ1
.
4.8. Crystal data for 3c
4.6. Single-crystal X-ray diffraction
C
87H10N9O6, Mr = 1372.79, 0.48 ꢂ 0.14 ꢂ 0.10 mm3, orthorhom-
Crystallization of 3a and 3c from a mixture of dichloromethane
and acetonitrile, at room temperature led to the formation of single
crystals that were suitable for X-ray diffraction studies. However,
these crystals proved to be unstable under ambient conditions
and consequentially collapsed during desolvation. After many
attempts, we managed to rapidly mount the crystals on the diffrac-
tometer for single-crystal X-ray diffraction experiments. Generally,
the quality of the crystals was poor as evidenced by the X-ray
diffraction data and the size of the anisotropic displacement
parameters of both host and guest. In particular, the crystals of
3c are weakly diffracting and the diffraction limit was only
0.96 Å. In addition, the thermal ellipsoids of the carbon atoms
belonging to the terminal cyclohexane rings were bigger then ellip-
soids of the remaining atoms. This is indicative of the cyclohexane
rings undergoing a conformational change in the part of unit cells
or due to solvent molecules leaving the crystal.
bic, space group P212121, a = 11.1597(4), b = 25.2349(9), c = 33.395
(2) Å, V = 9404.5(7) Å3, Z = 4, Dx = 0.970 g/cm3, F000 = 2952, CuK
a
radiation, k = 1.54178 Å, T = 130(2)K, 2hmax = 146.8°, 70,900 reflec-
tions collected, 18,523 unique (Rint = 0.062). Final GooF = 1.06,
R1 = 0.095, wR2 = 0.298, R indices based on 12,176 reflections with
I > 2r
(I) (refinement on F2), 926 parameters, 261 restraints. Lp and
absorption corrections applied,
l
= 0.48 mm-1. Absolute structure
parameter = 0.2(2).28
Solvent contributions were removed from the diffraction data
using SQUEEZE. Electron count for 3c is 678 in an accessible void
volume 2318.3 Å3. Restraints for the 1,2- and 1,3-distances as well
as the ADP restraint (SIMU) and rigid-bond restraint (DELU) were
applied.
CCDC-1565329 (3a) and 1565330 (3c) contain the supplemen-
tary crystallographic data for this paper. This data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data%5Frequest/cif.
The huge differences in calculated and experimental molecular
conformations of the 3a and 3c result mainly from the fact that the
calculation procedures do not take into account the influence of
the crystal environment (the solid state), which in turn can force
changes that are not energetically preferable in the isolated state
(in the gas phase).
Acknowledgements
The authors thank the National Science Centre in Poland, grant
no UMO-2012/06/A/ST5/00230 for financial support. The calcula-
tions were performed at Poznan Supercomputing and Networking
Centre (grant no. 217).
Crystals suitable for single-crystal X-ray diffraction were
obtained from the slow evaporation of a mixture of dichloro-
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021

M. Petryk et al. / Tetrahedron: Asymmetry xxx (2017) xxx–xxx
11
12. Janiak, A.; Petryk, M.; Barbour, L. J.; Kwit, M. Org. Biomol. Chem. 2016, 14, 669–
673. and references therein.
References
13. Petryk, M.; Biniek, K.; Janiak, A.; Kwit, M. CrystEngComm 2016, 18, 4996–5003.
14. Je˛drzejewska, H.; Szumna, A. Chem. Rev. 2017, 117, 4863–4899.
15. Reinhard, D.; Schöttner, L.; Brosius, V.; Rominger, F.; Mastalerz, M. Eur. J. Org.
Chem. 2015, 3274–3285.
1. Martí-Centelles, V.; Pandey, M. D.; Burguete, M. I.; Luis, S. V. Chem. Rev. 2015,
115, 8736–8834.
2. Rowan, S. J.; Cantrill, S. J.; Cousins, G. R. L.; Sanders, J. K. M.; Stoddart, J. F.
Angew. Chem., Int. Ed. 2002, 41, 898–952.
3. Gawronski, J.; Kolbon, H.; Kwit, M.; Katrusiak, A. J. Org. Chem. 2000, 65, 5768–
5773.
4. Gawron´ ski, J.; Kwit, M.; Rychlewska, U. Trianglamines and Related Chiral
Macrocycles In Comprehensive Supramolecular Chemistry II; Atwood, J. L., Ed.;
Elsevier: Oxford, 2017; Vol. 3, pp 267–291.
5. Kwit, M.; Plutecka, A.; Rychlewska, U.; Gawronski, J.; Khlebnikov, A. F.;
Kozhushkov, S. I.; Rauch, K.; de Meijere, A. Chem. Eur. J. 2007, 13, 8688–8695.
6. Bru, M.; Alfonso, I.; Burguete, M. I.; Luis, S. V. Tetrahedron Lett. 2005, 46, 7781–
7785.
7. Bru, M.; Alfonso, I.; Burguete, M. I.; Luis, S. V. Angew. Chem., Int. Ed. 2006, 45,
6155–6159.
8. Alfonso, I.; Bolte, M.; Bru, M.; Burguete, M. I.; Luis, S. V.; Rubio, J. J. Am. Chem.
Soc. 2008, 130, 6137–6144.
9. Bru, M.; Alfonso, I.; Bolte, M.; Burguete, M. I.; Luis, S. V. Chem. Commun. 2011,
283–285.
´
16. Gregolinski, J.; Lisowski, J.; Lis, T. Org. Biomol. Chem. 2005, 3, 3161–3166.
17. Petryk, M.; Troc´, A.; Gierczyk, B.; Danikiewicz, W.; Kwit, M. Chem. Eur. J. 2015,
21, 10318–10321.
18. Scigress 2.4, Fujitsu Ltd.
19. Gaussian 09, Revision D.01; Gaussian: Wallingford CT, 2009.
20. Spek, T. L. Acta Crystallogr. A 1990, 46, 194–201.
21. Flack, H. D.; Bernardinelli, G. J. Appl. Crystallogr. 2000, 33, 1143–1148.
22. CrysAlisPro 1.171.38.41, Rigaku Oxford Diffraction, 2015.
23. Burla, M. C.; Caliandro, R.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.;
Giacovazzo, C.; Mallamo, M.; Mazzone, A.; Polidori, G.; Spagna, R. J. Appl.
Crystallogr. 2012, 45, 351–356.
24. Sheldrick, G. M. Acta Crystallogr. A 2015, 71, 3–8.
25. Barbour, L. J. J. Supramol. Chem. 2001, 1, 189–191.
26. POV-RayTM for Windows, version 3.6; Persistence of Vision Raytracer Pty Ltd:
Williamstown, Australia, 2004
27. Bruno, I. J.; Cole, J. C.; Edgington, P. R.; Kessler, M.; Macrae, C. F.; McCabe, P.;
Pearson, J.; Taylor, R. Acta Crystallogr. B 2002, 58, 389–397.
28. Flack, H. D. Acta Crystallogr. 1983, A39, 876–881.
10. Korupoju, S. R.; Zacharias, P. S. Chem. Commun. 1998, 1267–1268.
11. Kwit, M.; Gawronski, J. Tetrahedron: Asymmetry 2003, 14, 1303–1308.
Please cite this article in press as: Petryk, M.; et al. Tetrahedron: Asymmetry (2017), http://dx.doi.org/10.1016/j.tetasy.2017.08.021