1 Hand 13 C NMR spectral data of bioactive cage-like polycyclic compounds

Article abstract of DOI:10.1002/mrc.2588

Bioactive cage-like polycyclic compounds have attracted the attention of several research groups because of their unique appearance and their biological activities. Their structures were established on the basis of ¹ HNMR and ¹³ CNMR

Full text of DOI:10.1002/mrc.2588

MRC Letters
Received: 16 December 2009
Revised: 2 February 2010
Accepted: 4 February 2010
Published online in Wiley Interscience: 18 March 2010
(www.interscience.com) DOI 10.1002/mrc.2588
1H and 13C NMR spectral data of bioactive
cage-like polycyclic compounds
Roberta C. Salles,a Valdemar Lacerda Jr,a∗ Adilson Beatriz,b Felicia M. Ito,b
a
a
a
´
Reginaldo B. dos Santos, Sandro J. Greco, Eustaquio V. R. de Castro
b
ˆ
and Denis P. de Lima
Bioactive cage-like polycyclic compounds have attracted the attention of several research groups because of their unique
appearance and their biological activities. Their structures were established on the basis of 1H NMR and 13C NMR spectroscopic
data. The 1H and 13C signal assignments and most homonuclear hydrogen coupling constants were assigned by use of
techniques such as 1D 1H and 13C NMR and 2D gCOSY, non-edited gHSQC and gHMBC. The gNOESY experiments proved the
c
endo-stereochemistry. Copyright ꢀ 2010 John Wiley & Sons, Ltd.
Keywords: 1H 13C NMR; gCOSY; gHSQC; gHMBC; gNOESY; cage-like compounds
Introduction
specific way with a biological receptor. However, no detailed NMR
studyofthesecompoundscouldbefoundintherelevantliterature.
In this study, we present a detailed assignment of NMR data
for the bioactive cage-like polycyclic compounds 1–6, including
the measurement of most homonuclear hydrogen coupling
constants and a complete assignment of NMR signals. The 2D
NMR (gCOSY,[12] gHSQC,[13] gHMBC[14] and gNOESY[15]) data are
also presented. The availability of reliable NMR data for this class
of compounds can provide easier and faster identification of both
current cage-like compounds and new ones.
Since 1930, cage-like compounds have attracted the attention
of several research groups due to their unique appearance and
their biological activities. The milestone in the study of these
compounds was the classical synthesis of Cookson’s diketone
in 1928.[1] In the synthesis proposed by Cookson, a pentacy-
clodiketone (1a) (Scheme 1), which contains an important cycle
of four members was formed through an intramolecular reaction
photocyclization adduct 1, obtained from a Diels–Alder reaction.
The biological activity of cage-like compounds was only
discovered in 1964 by Davies et al.[2] It was demonstrated in
their study that amantadine has antiviral activity. Later, in 1969,
Schwab et al.[3] showed that amantadine is also beneficial for
patients with Parkinson’s disease.
Experimental
Materials
From this work, other cage-like compounds were synthesized
and new biological activities were studied.[4–8] The studies show
that the cage-like structures are useful in specific interaction
with biological receptors and/or competitive inhibition or
non-competitive with smaller chemical species in their inside.[9]
These rigid structures enhance lipophilicity through cell
membranes, increasing their affinity for lipophilic regions in the
recipients, and providing metabolic stability, which may prolong
the pharmacological effect, thereby reducing the dosage.[10,11]
An important factor in the study of these compounds is the cor-
rect knowledge of their structure since they can interact in highly
The bioactive cage-like polycyclic compounds used in this present
study were prepared from cyclopentadiene and p-benzoquinone
as described in the relevant literature and shown in Schemes 2
and 3.[16]
NMR measurements
1
1H NMR, 13C NMR, 13C{ H}, DEPT, gCOSY, gNOESY, gHSQC and
gHMBC experiments were performed on a Bruker Avance DPX
300 spectrometer equipped with a 5-mm direct probe with z-
gradient field. 1H and 13C NMR spectra (at 300 and 75 MHz,
respectively) were measured at a temperature of 300 K, using
∗
Correspondence to: Valdemar Lacerda Jr, Departamento de Química, Centro
H
ˆ
de Ciencias Exatas da Universidade Federal do Espirito Santo, Av. Fernando
H
O
´
Ferrari 514, 29.075-910 Vitoria, ES, Brazil. E-mail: vljuniorqui@gmail.com
hv
ˆ
Departamento de Química, Centro de Ciencias Exatas da Universidade Federal
a
O
O
´
do Espirito Santo, Av. Fernando Ferrari 514, 29.075-910 Vitoria, ES, Brazil
O
(1)
(1a)
ˆ
b
Departamento de Química, Centro de Ciencias Exatas e Tecnologia da
Universidade Federal do Mato Grosso do Sul, Av. Senador Filinto Mu¨ler 1555,
79.074-460, Campo Grande MS, Brazil
Scheme 1. Intramolecular cyclization of the Diels–Alder adduct 1.
Magn. Reson. Chem. 2010, 48, 409–415
c
Copyright ꢀ 2010 John Wiley & Sons, Ltd.

R. C. Salles et al.
O
O
O
cyclopentadiene
O
(1)
p-benzoquinone
Scheme 2. Preparation of the adduct 1 from the Diels–Alder reaction.
H11
′
H11
11
1
10
O
2
Zn/AcOH
NaBH4
O
O
8
9
3
7
6
55-60°C
12h
H4 MeOH/H2O
4
5h
O
H4′
H5
H5′
O
HO
5
H6
(3)
(2)
(1)
MeO
MeO
MeO
O
O
Cl
O
H10
Br
O
O
NBS
CH2Cl2
H10
′
O
O
12
Toluene
Pyridine
O
O
13
HO
14
15
18
17
(6)
(3)
(5)
21
19
OMe
MeO
16
20
OMe
(4)
Scheme 3. Preparation of the compounds studied.
10 mg ml−1 in CDCl3 as solvent. Tetramethylsilane was used as an
internal reference. Chemical shifts are given on the δ scale. The
experiments were performed through standard pulse sequences,
as suggested by the equipment manufacturer. Typical parameters
were as follows.
ThenumberofscansforthegCOSY,gNOESY,gHSQCandgHMBC
was 16, 16, 32 and 64, respectively. The gNOESY experiments
were performed on degassed samples with a mixing time of
800 ms. Recording parameters were take from standard Bruker
microprograms.
For 1H NMR analysis, 16 transients were acquired with a 1-s
relaxation delay using 64 K data points. The 90◦ pulse was 8.0 µs
Results and Discussion
1
with a spectral width of 3612 Hz. 13C{ H} and DEPT spectra were
obtained for a spectral width of 23 809 Hz, collecting 64 K data
Compounds 1–6 were prepared from a Diels–Alder reaction
between cyclopentadiene and p-benzoquinone (Scheme 2).
From the adduct of Diels–Alder adduct 1, the studied
compounds were synthesized, as shown in Scheme 3.[16]
points. The 90◦ pulse was 14.5 µs. Overall, 1024 transients were
1
acquired for 13C{ H} and 512 transients for DEPT with a relaxation
delay of 2 s.
Table 1. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY and
gHMBC spectra for compound 1a
C
δ (13C)
δ (1H)
Coupling constants (Hz)
Multiplicity
gCOSY
gHMBC
1/8
2/7
3/6
4/5
9/10
11
48.2
48.7
3.49 (2H)
3.18 (2H)
–
1.7
1.7
sept
H2; H7; H9; H10; H11; H11’
C2; C7; C11
C9; C10; C3; C6; C1; C8
–
t
–
H1; H8
–
199.3
141.9
135.2
48.6
–
6.52 (2H)
6.01 (2H)
H11 – 1.39 (1H)
–
s
–
C3; C6; C2; C7
C2; C7; C11
1.7
t
H1; H8
H11ꢁ; H1; H8
H11; H1; H8
8.2; 1.7
8.2; 1.7
dt
dt
C9; C10
ꢁ
H11 – 1.48 (1H)
C9; C10; C1; C8
a In CDCl3 solution, all these assignments are in agreement with the gCOSY, gHSQC and gHMBC spectra.
c
Copyright ꢀ 2010 John Wiley & Sons, Ltd.
www.interscience.wiley.com/journal/mrc
Magn. Reson. Chem. 2010, 48, 409–415

MRC Letters
Table 2. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY and
gHMBC spectra for compound 2a
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
1/8
2/7
3/6
4
47.4
51.8
3.40 (2H)
3.17 (2H)
–
1.7
1.7
–
sept
H2; H7; H9 e H10; H11; H11’
C2; C7
C3; C6; C9; C10; C11
–
t
–
H1; H8
–
209.6
37.8
H4 – 2.59 (1H)
–
m
H4’; H5’
H4; H5
C3; C6; C5
ꢁ
H4 – 2.26 (1H)
5
37.8
H5 – 2.59 (1H)
–
m
H4’; H5’
H4; H5
C3; C6; C4
ꢁ
H5 – 2.26 (1H)
9/10
11
136.5
48.7
6.13 (2H)
1.7
t
H1; H8
C1; C8
H11 – 1.31 (1H)
8.6; 1.7
8.6; 1.7
dt
dt
H11’; H1; H8
H11; H1; H8
C1; C8; C9; C10
ꢁ
H11 – 1.43(1H)
C2; C7; C3; C6; C9; C10
a In CDCl3 solution, all these assignments are in agreement with the gCOSY, gHSQC and gHMBC spectra.
Table 3. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY,
gHMBC and gNOESY spectra for compound 3a
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
GNOESY
1
2
3
4
45.7
51.3
3.16 (1H)
2.79 (1H)
–
–
br.s
dd
–
H2; H10; H11; H11’
–
C1; C3; C7; C10
–
H9; H10; H11; H11’
10.1; 4.1
H7; H1
–
H11
–
213.7
35.9
–
–
H4 – 2.09 (1H)
m
H5; H5’
C3; C5; C6
–
ꢁ
H4 – 2.09 (1H)
5
27.6
H5 – 1.72 (1H)
–
m
H4; H4’; H6
C3; C4; C6; C7
–
ꢁ
H5 – 1.72 (1H)
6
67.4
45.6
4.22 (1H)
2.76 (1H)
–
m
td
H5; H5’; H7
H2; H6; H8
H7; H9; H11; H11’
H10; H8
C2; C7
C2; C3; C8
–
7
10.1; 4.1
–
H11
8
44.9
2.99 (1H)
br.s
dd
dd
dt
C2; C7
H11
9
135.1
136.4
49.8
6.11 (1H)
5.5; 3.0
5.5; 3.0
8.2; 1.4
8.2; 1.4
C7; C8; C10; C11
C1; C11
H1
10
11
6.03 (1H)
H9; H1
H1
H1; H2; H7; H8
H1
H11ꢁ – 1.25 (1H)
H11’; H1; H8
H11; H1; H8
C1; C2; C7; C8; C9; C10
H11 – 1.31 (1H)
dt
a In CDCl3 solution, all these assignments are in agreement with the gCOSY, gHSQC, gHMBC and gNOESY spectra.
Table 4. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY,
gHMBC and gNOESY spectra for compound 4a
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
gNOESY
1
2
3
4
45.4
51.7
2.99 (1H)
3.04 (1H)
–
–
m
dd
–
H2; H10; H11; H11’
H7; H1
C3
H10
H4; H6; H11
–
5.4; 2.7
C8
–
211.5
35.6
–
–
H4 – 2.25 (1H)
–
–
m
H4’; H5; H5’
H4; H5; H5’
H4; H4’; H5’; H6
H4; H4’; H5; H6
H5; H5’; H7
H2; H6
C3; C5; C6
H2; H5; H6
H5’
ꢁ
H4 – 2.31 (1H)
m
5
25.6
H5 – 2.01 (1H)
–
m
C3; C6; C7
H4; H6; H7
H4’
ꢁ
H5 – 2.09 (1H)
–
m
6
70.0
44.4
5.58 (1H)
3.07 (1H)
7.4; 5.4; 2.9
5.4; 2.9
–
ddd
dd
br.s
dd
dd
dt
–
C2; C9
–
H2; H4; H5
H5; H11
H9; H11; H11’
H8
7
8
45.0
3.30 (1H)
H9; H11; H11’
H10; H8
9
135.8
135.4
49.7
6.18 (1H)
5.6; 2.7
5.6; 2.7
8.4; 2.7
8.4; 2.7
C8
10
11
6.00 (1H)
H9; H1
C8
H1
H11ꢁ – 1.31 (1H)
H11; H8; H1
H11’; H8; H1
C9
H2; H7; H8
H8
H11 – 1.43 (1H)
dt
C2; C8; C9
c
Magn. Reson. Chem. 2010, 48, 409–415
Copyright ꢀ 2010 John Wiley & Sons, Ltd.
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R. C. Salles et al.
Table 4. (Continued)
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
gNOESY
12
165.1
125.0
106.8
152.9
142.2
56.2
–
–
–
–
–
–
–
–
–
–
s
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
13
–
–
14
7.14 (2H)
–
C12; C13; C15; C16
15
–
–
s
–
16
–
–
19/21
20
3.88 (6H)
3.88 (3H)
C16
C15
60.9
s
a In CDCl3 solution, all these assignments are in agreement with the gCOSY, gHSQC, gHMBC and gNOESY spectra.
Table 5. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY,
gHMBC and gNOESY spectra for compound 5a
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
gNOESY
1
2
3
4
39.3
51.2
2.43 (1H)
2.60 (1H)
–
–
m
m
–
H2; H10; H10’; H11; H11’
H1; H10’
–
H10
–
–
–
–
214.0
35.1
–
–
–
H4 – 2.49 (1H)
–
m
m
m
m
td
t
H4’; H5; H5’
H4; H5; H5’
H4; H4’; H5’; H6
H4; H4’; H5; H6
H7; H5; H5’
H6; H8
C3; C5; C6
H6
ꢁ
H4 – 2.30 (1H)
–
–
5
26.5
H5 – 2.20 (1H)
–
C3; C4; C6; C7
C4
H6
ꢁ
H5 – 1.87 (1H)
–
3.7; 1.6
3.7
–
H4; H5
H11
6
74.4
43.5
49.1
79.6
37.2
4.26 (1H)
2.54 (1H)
C2; C4
7
C2; C3; C5; C6; C9
C2; C11
8
2.93 (1H)
–
m
t
H7; H9; H11; H11’
H10; H8
H10
9
4.44 (1H)
6.2
C10
H10
10
H10ꢁ – 1.40 (1H)
H10 – 1.48 (1H)
H11ꢁ – 1.55 (1H)
H11 – 1.34 (1H)
–
m
ddd
dt
dt
H1; H9; H10’
H10; H1; H2
H11’; H1; H8
H11; H1; H8
C2; C9
H1; H8; H9
–
7.1; 3.0; 1.8
10.6; 1.5
10.6; 1.5
C2; C8; C9; C11
C10
11
37.4
H7
C2; C7; C8; C10
–
a In CDCl3 solution, all these assignments are in agreement with the gCOSY, gHSQC, gHMBC and gNOESY spectra.
Table 6. 1H and 13C NMR chemical shifts, δ (ppm), multiplicities and coupling constants J(1H,1H) (Hz), 1H–1H and 1H–13C correlations in gCOSY,
gHMBC and gNOESY spectra for compound 6a
Coupling
constants (Hz)
C
δ (13C)
δ (1H)
Multiplicity
gCOSY
gHMBC
gNOESY
1
2
3
4
46.9
49.8
2.71 (1H)
2.75 (1H)
–
–
Br.s
t
H2; H11; H11’
H1; H7
C3; C7; C10
C1; C7
H10; H11
4.0
–
211.7
35.0
–
–
–
–
–
H4 – 2.34 (1H)
–
m
H4’; H5; H5’
H4; H5; H5’
H5’; H4; H4’; H6
H5; H4; H4’; H6
H7; H5’; H5
H2; H6; H8
H7; H9
C3; C5; C6
H6
ꢁ
H4 – 2.37 (1H)
–
m
–
H6
5
25.8
H5 – 1.89 (1H)
13.8; 11.0; 6.9; 2.0; 0.6
ddddd
ddd
td
C4
ꢁ
H5 – 2.26 (1H)
13.8; 6.9; 4.0
–
6
75.2
42.2
48.5
88.4
55.0
34.8
4.27 (1H)
2.57 (1H)
4.0; 2.0
C2; C4
H4; H5; H7; H8
H6; H11
H6; H9; H11; H11’
H8; H10; H11’
H1
7
10.2; 4.0
dt
C2; C4
8
2.99 (1H)
–
5.2
2.1
–
m
C2
9
4.58 (1H)
d
H8
–
10
11
3.71 (1H)
d
H11
C8; C9; C11
–
H11ꢁ – 1.65 (1H)
m
H1; H8; H10; H11’
H1; H8; H11
H1; H7; H8
H8; H9
H11 – 2.18 (1H)
–
m
a In CDCl3 solution. All these assignments are in agreement with the gCOSY, gHSQC, gHMBC and gNOESY spectra.
c
Copyright ꢀ 2010 John Wiley & Sons, Ltd.
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Magn. Reson. Chem. 2010, 48, 409–415

MRC Letters
(a)
(b)
Figure 1. Experimental (a) and simulated (b) second-order coupling pattern signals of hydrogens 4 and 5 of compound 2.
H2
H7
H2
H8
H7
H1
H7
H2
H8
H1
H6
H6
H10
Figure 2. Expansion of 2D NMR spectrum (1H, 1H-COSY) of compound 3.
H9
The unequivocal assignment of 1H and 13C NMR signals of
Figure 3. Expansion of 2D NMR spectrum (1H, 1H-COSY) of compound 4.
compounds 1–6 is listed in Tables 1–6.
The signals of hydrogens 4 and 5 of compound2 are multiplets
and have a second-order coupling pattern. They were simulated
in the SimEsp NMR software,[17] in which a great deal of similarity
to the experimental spectrum was observed (Fig. 1).
and H10. The bridge hydrogens (H11 and H11ꢁ) were assigned by
the 2D gNOESY NMR spectrum in which the signal of H11 was
ꢁ
The distinction between hydrogens H2 and H7 of 3 was
confirmed by analyzing the 2D gCOSY spectrum (Fig. 2) where the
H7 couples with H8 and H6 (δ = 2.76 ppm) and H2 (δ = 2.79 ppm)
with H1. From the HMBC experiment, it was possible to assign the
signals of C9 and C10 and from the HSQC experiment those of H9
attributed to the larger chemical shift value. The determination
of the endo/exo stereochemistry was done in a trustworthy way
based upon the observed coupling between the bridge hydrogen
H11 and hydrogens H2 and H7 in the 2D NOESY NMR spectrum.
This attribution is possible only in endo configuration.
c
Magn. Reson. Chem. 2010, 48, 409–415
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R. C. Salles et al.
H6
H4
H5’
H4’
H5
C5
H5
H4
H7
H8
C4
Figure 4. Expansionof2DNMRspectrum(1H,DEPT-HSQC)ofcompound 5.
Figure 5. Expansion of 2D NMR spectrum (1H, 1H-NOESY) of compound 6.
In the 1H NMR spectrum of 4, the distinction between
the hydrogens H1 (δ = 2.99 ppm), H2 (δ = 3.04 ppm), H7
(δ = 3.07 ppm)andH8 (δ = 3.30 ppm)wasmadewiththeaidof2D
gCOSY and gHMBC NMR spectra in which the couplings between
hydrogens H8 and H9, H7 and H6 as well as between H1 and H10 can
be observed (Fig. 3). With these assignments and using a gHSQC
spectrum,itwaspossibletoassignthesignalsofC1 (δ = 45.4 ppm),
C2 (δ = 51.7 ppm), C7 (δ = 44.4 ppm) and C8 (δ = 45.0 ppm).
With the gNOESY spectrum, it was possible to assign the signals of
hydrogensH11 andH11ꢁ andthestereochemistryasdescribedfor 3.
The signals of the hydrogens 5, 5ꢁ and 7 of 5 were attributed
on the basis of the 2D gCOSY and gHMBC spectra. With these
assignments, it was possible to make a distinction between
carbons C4 and C5 through the gHSQC spectrum (Fig. 4).
(a)
JH5, H5’ = 13,8
JH5, H4 = 11,0
JH5, H4’ = 6,9
JH5, H6 = 2,0
JH5, H? = 0,6
(b)
Figure 6. Experimental (a) and simulated (b) signals of hydrogen H5 of compound 6.
c
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Magn. Reson. Chem. 2010, 48, 409–415

MRC Letters
The assignments of the hydrogens H4, Hꢁ4, H5 and H5ꢁ of 6 were
performed with the aid of 2D gNOESY spectrum, in which it is
possible to observe contacts of hydrogens H4 and H5 with H6
(Fig. 5). In this spectrum, we can also see the spatial proximity of
H2 and H11 and assign the bridge hydrogens H11 (δ = 1.65 ppm)
and H11ꢁ (δ = 2.18 ppm).
[3] R. S. Schwab, A. C. England Jr, D. C. Poskanzer, R. R. Young, JAMA
1969, 208, 1168.
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Acknowledgements
The authors thank the Fundac¸a˜o de Amparo a` Pesquisa do Es-
tado do Espírito Santo (FAPES/FUNCITEC), the Conselho Nacional
de Desenvolvimento Científico e Tecnolo´gico (CNPq), the Co-
ordenadoria de Aperfeic¸oamento de Pessoal do Nível Superior
(CAPES), the Fundac¸a˜o de Apoio ao Desenvolvimento do Ensino,
Cieˆncia e Tecnologia do Estado de Mato Grosso do Sul (FUNDECT)
and Laborato´rio Pesquisa e Desenvolvimento de Metodologias
para Ana´lise de Petro´leos do Departamento de Química da UFES
(LabPetro-DQUI/UFES), for financial support.
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c
Magn. Reson. Chem. 2010, 48, 409–415
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