Total Synthesis and Evaluation of B-Homo Palmatine and Berberine Derivatives as p300 Histone Acetyltransferase Inhibitors

Article abstract of DOI:10.1002/ejoc.201701693

Palmatine and berberine, structurally similar isoquinoline alkaloids exhibiting a broad range of biological activities, were recently found to inhibit p300 histone acetyltransferase (HAT), a potential therapeutic target for treating transcriptional activator-driven malignancies and diseases. Here, we report the first total synthesis of B-homo palmatine (11a) and berberine (11b) derivatives, which were synthesized from 3,4-dimethoxybenzaldehyde (1a) and benzo[d][1,3]dioxole-5-carbaldehyde (1b) in nine steps in 13.8 and 16.9 % overall yields, respectively. A number of other new B-homo palmatine and berberine derivatives were also prepared. These derivatives display good inhibitory activity against p300 HAT; compound 12a manifests the most potent inhibition with an IC₅₀ value of 0.42 μm. Cell-based assays revealed that 12a exhibits certain inhibitory activity against HCG27, HT1080, and Z-138 cell lines, and no visible activity towards other cancer cell lines tested, reflecting that 12a has low cytotoxicity and acts against some types of cancer cells.

Full text of DOI:10.1002/ejoc.201701693

A Journal of
Accepted Article
Title: Total Synthesis and Evaluation of New B-homo Palmatine
and Berberine Derivatives as p300 Histone Acetyltransferase
Inhibitors
Authors: Zhongzhen Yang, Yong Zhang, Xin Chen, Weijian Li, Guo-Bo
Li, and Yong Wu
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10.1002/ejoc.201701693
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Total Synthesis and Evaluation of New B-homo Palmatine and
Berberine Derivatives as p300 Histone Acetyltransferase
Inhibitors
Zhongzhen Yang,[a] Yong Zhang,[a] Xin Chen,[b] Weijian Li,[a] Guo-Bo Li,*[a] Yong Wu*[a]
Abstract: Palmatine and berberine are structurally similar
isoquinoline alkaloids exhibiting a broad range of biological activities,
which were found recently to have inhibitory activity against the p300
histone acetyltransferase (HAT), a potential therapeutic target for
treating transcriptional activator-driven malignancies and diseases.
Here, we report the first total synthesis of the B-homo palmatine
(11a) and berberine (11b) derivatives, which were synthesized from
3,4-dimethoxybenzaldehyde (1a) and benzo[d][1,3]dioxole-5-
carbaldehyde (1b) in nine steps in 13.8% and 16.9% overall yields,
Palmatine and berberine are tetracyclic isoquinoline alkaloids
(Figure 1a) found in such plants as Coptis chinensis (Chinese name:
Huang-Lian), Phellodendron amurense, and Corydalis yanhusuo.[4]
Many studies revealed that palmatine and berberine exhibit a wide
range of biological activity and have therapeutic potential against
bacterial infection, diabetes, cancer, arrhythimia, hypertension,
inflammation, flavivirus, and liver-related diseases.[5] We recently
identified that palmatine and berberine have p300 histone
acetyltransferase (HAT) inhibition with IC50 values of 1.05 μM and
respectively.
A
number of other new B-homo palmatine and
9.2 μM, respectively (Figure 1a);[6] p300 HAT is
a crucial
berberine derivatives were also prepared. These derivatives
displayed good inhibitory activity against p300 HAT; 12a manifests
the most potent inhibition with an IC50 value of 0.42 μM. Cell-based
assays revealed that 12a exhibited certain inhibitory activity to the
HCG27, HT1080, and Z-138 cell lines, and no visible activity to other
cancer cell lines tested, reflecting that 12a has low cytotoxicity, and
acts against some types of cancer cells.
transcription factor for gene regulation, and its dysfunctions
contribute to the development of multiple diseases, including
cancer.[7] Since p300 HAT is a relatively difficult target (probably due
to its tight-binding substrate Ac-CoA or CoA),[8] there is a lack of
potent p300 HAT inhibitors at present, the development of new
palmatine and berberine derivatives would be an impetus to discover
more potent p300 HAT inhibitors and to develop potential new
agents for the treatment of associated diseases.
Introduction
Natural products have been a rich source of useful starting materials
for drug discovery.[1] During the last three decades, a third of new
medicines approved by the US Food and Drug Administration (FDA)
were natural products or direct derivatives of natural products.[1-2]
Natural products that were developed as clinically useful drugs have
been considered to have the ‘metabolite-likeness’ property, i.e.
which are biologically active but also likely to be substrates of
transporter systems that can deliver them to the intracellular site of
action.[1a] Notably, natural products possess special chemical
scaffolds,
diverse
pharmacophores
and/or
advanced
stereochemistry, which may interrogate some difficult molecular
targets, such as protein–protein interactions, featureless binding
sites, and transcription factors.[3]
[a] Z. Yang, Y. Zhang, W. Li, Dr. G.-B. Li, Pro. Dr. Y. Wu.
Key Laboratory of Drug Targeting and Drug Delivery System of Ministry of
Education, West China School of Pharmacy, Sichuan University, Sichuan 610041,
China.
Figure 1. (a) Chemical structure of palmatine and berberine and their potency to
p300 HAT. (b) The representative reported palmatine and berberine derivatives. (c)
The B-homo palmatine and berberine derivatives presented in this work.
Email: liguobo@scu.edu.cn (G.-B. Li); wyong@scu.edu.cn (Y. Wu)
[b]
X. Chen
The previous studies mainly focused on modifications of the
peripheral functional groups of palmatine and berberine, which led to
various substituted derivatives (Figure 1b).[9] We are more interested
in modifying the core tetracycle of palmatine and berberine to obtain
Laboratory of Biotherapy and Cancer Center, West China Hospital, West China
Medical School, Sichuan University, Sichuan 610041, China
Supporting information and the ORCID identification numbers for the author(s)
of this article can be found under:
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10.1002/ejoc.201701693
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novel derivatives, such as the B-homo palmatine and berberine
derivatives (Figure 1c), with aim to expand the diversity of naturally
derived chemical scaffolds; to the best of our knowledge, there are
no reports of such tetracycle-modified derivatives whose synthesis
would be a challenge for us. Molecular docking analyses (for details
see Experimental section) indicated that the B-homo palmatine and
berberine derivatives are likely to have hydrogen-bonding,
electrostatic and hydrophobic interactions with the catalytically
important residues, including Arg1410, Thr1411, Trp1466, Tyr1467,
Asp1399, and Pro1458 (Figure S1 in Supplementary Information),
which is similar as that observed for palmatine.[6] Therefore, the
establishment of a feasible synthetic route for the B-homo palmatine
and berberine derivatives could not only expand the diversity of
palmatine and berberine derivatives but also help identify new potent
p300 HAT inhibitors. We here report first total synthesis of new B-
homo palmatine and berberine derivatives, and in vitro evaluation of
their activity against the p300 HAT.
using the similar conditions (g-i) as that for the preparation of 11a
(Scheme 1). The total yield of 12a was 13.6% in nine steps (Table
S1 in Supporting Information).
Results and Discussion
Total Synthesis of B-homo Palmatine Derivatives
The synthetic routes for new B-homo palmatine derivatives are
described in Schemes 1-2. Briefly, 3,4-dimethoxybenzaldehyde (1a)
was used as the starting material to prepare the intermediates 2a
[10]
and 3a according to the reported procedures
(Scheme 1). Then,
reduction of 3a using NaBH4 gave the alcohol 4a in 88.6% yield. The
alcohol 4a was converted to the intermediate 5a into the presence of
I2 and CF3COOAg according to the literature procedure.[11]
Sonogashira reaction of 5a with trimethylsilyacetylene (TMSA) in
presence of triethylamine with Pd(PPh3)2Cl2 and CuI afforded the
intermediate 6a (Scheme 1). Then, 6a was treated with
tetrabutylammonium fluoride trihydrate (TBAF) to remove the TMS
group, leading to the C-C coupling product 7a (Scheme 1). Further
Sonogashira reaction of 7a with 8 in presence of triethylamine with
Pd(PPh3)2Cl2 and CuI afforded the intermediate 9a (Scheme 1). The
cycloaddition of alkyene 9a and ammonium acetete with AgNO3
provided the 3-phenylisoquinoline derivative 10a (Scheme 1).[12]
Scheme 1. Synthetic routes for B-homo palmatine derivatives 11a and 12a. (a)
CH2(COOH)2, pyridine, piperidine, 115 ℃, 2h, 75.5%; (b) H2, 10% Pd/C, rt, 16 h,
78.7%; (c) NaBH4, I2, THF, 0-60 ℃, 10h 88.6%; (d) I2, CF3COOAg, CHCl3, rt, 0.5 h,
90.0%; (e) TMSA, PdCl2(PPh3)2, CuI, Et3N, 50 ℃, 5 h; (f) TBAF, THF, rt, 0.5 h,
88.7% (total yield of steps e and f); (g) PdCl2(PPh3)2, CuI, Et3N, 70 ℃, 3 h, 62.9% for
9a (65.3% for 9a’); (h) NH4OAc, AgNO3, t-BuOH, rt, 15 h, 61.1% for 10a (59.5% for
10a’); (i) CH3SO2Cl, Et3N, CH2Cl2, 0 - 50 ℃, 5 h, 85.2% for 11a (83.4% for 12a).
Four other B-homo palmatine derivatives (13a, 14a, 16a, and 17a)
were further synthesized as shown in Scheme 2. Compounds 13a
and 14a were synthesized by the vacuum reaction of 11a, followed
by the etherification of 11a’ by treatment with alkyl halides.
Compound 16a was synthesized by NaBH4 reduction of 11a,
followed by the reaction of 15a with (bromomethyl)benzene.
Compound 17a was prepared from 12a using the identical conditions
(l, m) as that for 16a. The overall yields for these prepared palmatine
derivatives are summarized in Table S1 (see Supplementary
Information).
It is worthy of note that the cyclization reaction of 10a was one of
the most important step in this synthetic routes. Initially, we have
tried out the cyclization reaction of 10a in the presence of
[12]
triphenylphosphine in DCM/CCl4 (V/V = 2/1)
and attempted to
synthesize 11a with 10a in the presence of dichlorosulfoxide in
acetonitrile [9a], but unfortunately, we failed to get intermediate 11a.
Finally, the cyclization reaction of 10a with methanesulphonyl
chloride gave the B-homo palmatine 11a. Together, this synthetic
route for 11a was achieved in nine steps in 13.8% over yield
(Scheme 1, Table S1 in Supporting Information). The B-homo
palmatine derivative 12a was synthesized from compound 7a and 8’
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Scheme 2. Synthetic routes for B-homo palmatine derivatives 13a, 14a, 16a, and
17a. (n) 180 ℃, in vacuum, 2 h, 90.6%; (o) alkyl halides (R-X), CH3CN, 85 ℃, 3 h,
20.7% for 13a (18.2% for 14a); (l) NaBH4, K2CO3, CH3OH, 0 - 65 ℃, 3 h; (m) BnBr,
CH3CN, 50 ℃, 3 h, total yield of steps l and m : 82.1% for 16a (84.6% for 17a).
Total Synthesis of B-homo Berberine Derivatives
Scheme 3. Synthetic routes for B-homo berberine derivatives 11b and 12b. (a)
CH2(COOH)2, pyridine, piperidine, 115 ℃, 2h, 77.2%; (b) H2, 10% Pd/C, rt, 16 h,
The synthesis of B-homo berberine derivatives is outlined in
Schemes 3-4. The B-homo berberine 11b and its derivative 12b
were prepared from the starting compound benzo[d][1,3]dioxole-5-
carbaldehyde (1b) using the conditions (a-i) that for the synthesis of
11a and 12a (Scheme 3). 11b and 12b were obtained by nine steps
in 16.9% and 15.2% over yield, respectively (Scheme 3, Table S1).
74.3%; (c) NaBH4, I2, THF, 0-60 ℃, 10h; (d) I2, CF3COOAg, CHCl3, rt, 0.5 h, 84.2%
(total yield of steps c and d); (e) TMSA, PdCl2(PPh3)2, CuI, Et3N, 50 ℃, 5 h, 74.2%;
(f) TBAF, THF, rt, 0.5 h, 98.3%; (g) PdCl2(PPh3)2, CuI, Et3N, 70 ℃, 3 h, 70.3% for 9b
(68.6% for 9b’); (h) NH4OAc, AgNO3, t-BuOH, rt, 15 h, 78.5% for 10b (74.1% for
10b’); (i) CH3SO2Cl, Et3N, CH2Cl2, 0 - 50 ℃, 5 h, 87.3% for 11b (85.3% for 12b).
Scheme 4 shows the synthetic routes for preparing berberine
derivatives 13b, 15b, 16b, 17b, 19b, 21b, and 22b. Compound 13b
was prepared by the reactions of 11b with CaO, followed by the
acidification of 11b’ by treatment with HCl in ethyl acetate.[13]
Compounds 15b, 16b, and 17b were synthesized by the vacuum
reaction of 11b at 180 ℃, followed by the etherification of 14b by
treatment with alkyl halides (Scheme 4). Compound 18b was
prepared by the halogenation of 11b with Br2, which was then
converted to 19b under Suzuki reaction conditions (Scheme 4).
Compound 21b was synthesized by NaBH4 reduction of 11b,
followed by the reaction of 20b with (bromomethyl)benzene.
Similarly, compound 22b was prepared from compound 12b using
the identical conditions (l, m) as for 21b. The overall yields for these
berberine derivatives are summerized in Table S1 (see
Supplementary information).
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Table 1. The calculated logP values, the inhibitory activities (IC50) and LE
values to p300 HAT of the new B-homo palmatine derivatives.
p300 HAT
IC50 (μM)
Cpd
Chemical Structure
clogPa
0.58
LEb
11a
4.5
0.28
12a
0.47
0.42
0.33
13a
14a
1.91
1.89
4.7
9.4
0.23
0.20
16a
17a
4.33
4.32
4.7
7.4
0.22
0.21
a logP was calculated using the ALOGPS 2.1 program [14]
(http://www.vcclab.org/lab/alogps/; available on October 10, 2017).
b The ligand efficiency (LE) is calculated using the formula: LE = 1.4*(-
logIC50)/N, where N is the number of non-hydrogen atoms.[15]
The inhibition assays revealed that 11a, which has a heptatomic
B-ring, displayed a slight lower inhibitory activity (IC50 =4.6 μM,
Table 1) against p300 HAT than palmatine (IC50 = 1.05 μM), which
has
a hexatomic B-ring (Figure 1a); under the same assay
Scheme 4. Synthetic routes for berberine derivatives 13b, 15b, 16b, 17b, 19b, 21b,
and 22b. (j) CaO, CH3OH/H2O (pH = 9-10), rt - 60 ℃, 3 h; (k) HCl / ethyl acetate,
conditions, C646, a known p300 HAT inhibitor,[16] showed IC50 of 2.6
μM. Small differences between the minimum energy conformations
of 11a and palmatine (particularly in their A- and B-ring) were
observed (Figure S2 in Supplementary Information). Notably, shifting
the methoxyl group from the R1 position to the R2 position led to
compound 12a, which has markedly increased inhibitory activity
(IC50 = 0.42 μM, Table 1) against p300 HAT, comparing with 11a
(IC50 = 4.5 μM) and C646 (IC50 = 2.6 μM); the ligand efficicency (LE)
of 12a is 0.33. Compounds 13a and 14a, which bears aromatic
substituents at the R1 position, displayed comparable inhibitory
activity to 11a (IC50 = 4.5 μM, Table 1). Interestingly, 16a and 17a,
which both have a benzyl moiety on the quaternary amine, displayed
IC50 values of 4.7 μM and 7.4 μM, respectively, comparable to that of
11a (IC50 = 4.5 μM, Table 1). The LE values of 13a, 14a, 16a, and
17a are less than that of 12a (Table 1).
DCM, rt, 1 h, total yield of steps j and k: 35.7% for 13b; (n) 180 ℃, in vacuum, 2 h,
95.1%; (o) alkyl halides (R-X), CH3CN, 85 ℃, 3 h for 15b (23.2%), 16b (21.5%), and
17b (18.7%); (p) Br2, CH3COOH, 100 ℃, 8 h, 58.6%; (q) Na2CO3, Pd(PPh3)4, toluene,
EtOH, H2O, 100 ℃, 14 h, 20.2% for 19b; (l) NaBH4, K2CO3, CH3OH, 0 - 65 ℃, 3 h;
(m) BnBr, CH3CN, 50 ℃, 3 h, total yield of steps l and m: 84.0% for 21b (79.8% for
22b).
Biological Evaluation of the B-homo Palmatine and Berberine
Derivatives
The inhibitory activities (IC50) of the B-homo palmatine and berberine
derivatives to p300 HAT were tested using an isotope labelling
method as described in Experimental section. The IC50 values, the
calculated logP (clogP, predicted using the ALOGPS 2.1 program[14]
)
[15]
and ligand efficiency (LE)
values of the palmatine and berberine
derivatives are in Table 1-2. We observed that of these derivatives,
the molecular weights are less than 500, number of hydrogen-bond
donors less than 5, number of hydrogen-bond acceptors less than
10, and the lipid-water partition coefficients (clogP) less than 5
(Table 1), partly reflecting that they are drug-like compounds.
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Table 2. The calculated logP values, the inhibitory activities (IC50) and LE
values to p300 HAT of the new B-homo berberine derivatives.
studies revealed that the B-homo palmatine and berberine
derivatives have micromolar inhibition against p300 HAT, among
which 12a manifests the most potent inhibitory activity (IC50 = 0.42
μM).
p300 HAT
IC50 (μM)
Cpd
Chemical Structure
clogP
-0.01
LE
12b
1.8
0.31
13b
15b
0.1
13.3
6.7
0.26
0.25
1.15
16b
17b
0.95
1.44
3.5
2.5
0.27
0.25
19b
21b
1.51
4.03
11
34
0.22
0.19
Figure 2. The possible binding mode of 12a with p300 HAT and its
cellular inhibitory activity against cancer cells. (a) The predicted binding
mode of 12a with p300 HAT. (b) Cellular inhibitory activity of 12a against
various cancer cell lines at different concentrations (100 μM, 10 μM, and
1 μM). The results revealed that 12a has certain inhibitory activity to
HCG27, HT1080, and Z138 cell lines at 100 μM, and no visible activity to
other cancer cell lines.
22b
4.07
44
0.18
We then performed molecular docking studies for 12a to
investigate its possible binding mode with p300 HAT. The docking
results showed that 12a is likely to form hydrogen-bonding
interactions with Arg1410 (α3) and Thr1411 (α3), electrostatic
interactions with Asp1399 (β4), π-π stacking interactions with
His1451 (loop L1), and hydrophobic interactions with Gln1455 (loop
L1), Ile1457 (loop L1), Pro1458 (loop L1), and Pro1440 (loop L1)
(Figure 2a). Comparison of 12a with its highly similar derivative 11a
reveals that they may bind in a similar manner to the p300 HAT
domain, involving the catalytically important residues on loop L1, α3
and β4 (Figure S4 in Supplementary Information). Indeed, it is a big
challenge to obtain p300:inhibitor complex crystal structures;[17] in
future research, we will attempt crystallization for the complex of
p300:12a using the strategy reported by Lasko et al [7] to confirm the
Similarly, comparing with berberine (IC50 = 9.2 μM), 13b exhibited
slight lower inhibitory activity against p300 HAT with an IC50 value of
13.3 μM (Table 2), which may due to the small difference in their
minimum energy conformations (Figure S3 in Supplementary
Information). Compound 12b, with the methoxyl group at R2 position,
manifested IC50 of 1.8 μM (Table 2), similar with that observed for the
palmatine derivative 12a (IC50 = 0.42μM, Table 1). Compounds 15b,
16b, and 17b, which have different substituents at R1 position,
showed better inhibitory activities than 13b (Table 2), consistent with
that observed for the palmatine derivatives (Table 1). Compounds
19b, which has the benzene moiety at R3 position, displayed IC50
value of 11 μM. Notably, 21b and 22b (Table 2), which have a
benzyl moiety on the quaternary amine, showed lower inhibitory
activity against p300 HAT than that of the corresponding palmatine
derivatives 13a and 12a (Table 1). Taken together, these SAR
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inhibition mode and provide structural basis for further inhibitor
optimization.
Unless otherwise noted, all reactions were carried out in oven dried
glass flask under an air atmosphere. Solvents were purified and
dried according to standard methods prior to use. All the reactions
were monitored by thin-layer chromatography (TLC) and were
visualized using UV light. The product purification was done using
silica gel column chromatography. Thin layer chromatography (TLC)
characterization was performed with precoated silica gel GF254
(0.2mm), while column chromatography characterization was
performed with silica gel (100-200mesh). All new compounds were
characterized by NMR spectroscopy, and melting point (if solids). 1H
NMR spectra were recorded at 400 or 600 MHz (Varian) and 13C
NMR spectra were recorded at 150 MHz (Varian). Chemical shifts
are reported in ppm downfield from CHCl3 (δ = 7.26 ppm) for 1H
NMR and relative to the central CDCl3 resonance (δ = 77.0 ppm) for
13C NMR spectroscopy. Then the signal due to residual DMSO
appearing at δH 2.50 ppm and the central resonance of the DMSO -
We next tested the in vitro inhibitory activity of 12a against
several cancer cell lines, including HCG27 (gastric carcinoma), U266
(myeloma), HT1080 (epithelial, fibrosarcoma), Z-138 (mantle cell
lymphoma), and Hela (adenocarcinoma), as well as the HEK293T
(human embryonic kidney cells) for control. The results indicated
that 12a exhibited 33.6%, 23.6%, and 47.2% inhibition to the HCG27,
HT1080, and Z-138 cell lines at 100 μM, respectively (Figure 2b);
when treated with low concentrations of 12a, no visible activity was
observed for these cell lines (Figure 2b). We also observed that 12a
has no or low activity to other tested cancer cell lines as well as the
normal HEK293T cells (Figure 2b). These results indicated that 12a
has low cytotoxicity, and it only acts against some types of cancer
cells. For comparison, we tested the inhibitory activity of barberine
and palmatine against Z-138 cell lines, which is the most sensitive
tested cell lines to 12a. We observed that barberine and palmatine
displayed 32.5% and 21.2% inhibition to Z-138 at 100 μM,
respectively, slightly less potent than 12a. In general, the tested
cancer cells are not so sensitive to 12a, reflecting that p300 HAT
may not be an addiction target to these cancer cells, for which one
possible reason may be the CBP protein, the paralog of p300,
compensating the acetyltransferase activity of p300 when inhibited
by 12a. Hence, p300 HAT inhibitors are possibly effective against
CBP-deficient cancer cells as reported by Ogiwara et al.[18] Besides,
one may speculate that the low inhibitory activity of 12a in cells may
be due to its chemical structure, since the presence of a quaternary
amine may possibly decrease the cell membrane permeability
(except being carrier-mediated).[19]
1
d6 appearing at δC 39.5(2) ppm were used to reference H and 13C
NMR spectra, respectively. Coupling constants are given in Hz.
Chemical shifts (δ) were reported as parts per million (ppm)
downfield from tetramethylsilane and the following abbreviations
were used to identify the multiplicities: s = singlet, d = doublet, t =
triplet, q = quartet, m = multiplet, br = broad and all combinations
thereof can be explained by their integral parts. LC-MS spectra were
recorded on an Agilent 6400 series Triple Quadrupole LC-MS.
Melting points (m.p.) were recorded on an INESA SGW X-4 melting
point apparatus. Commercial reagent were purchased from Adamas
Reagent Co., Ltd., Best reagent and Astatech Chemical Technology
Co., Ltd. etc. All reagents were directly used without further
purification. High-resolution mass spectra were recorded using the
EI method with a double focusing magnetic mass analyzer. Unless
otherwise noted, all products are isolated yields. The 1H and 13C
NMR spectra of the prepared berberine derivatives are given in the
Supplementary information.
Conclusions
In conclusion, this work reported the first total synthesis of new B-
homo palmatine and berberine derivatives, which involves nine to
eleven steps with good overall yield (Table S1 in Supplementary
Information). These synthetic routes will be useful in exploring
structurally unique compounds, in particular the tetracycle-modified
palmatine and berberine derivatives. The SAR studies revealed that
these derivatives exhibit potent inhibition to p300 HAT, some of
which (e.g. 12a) are more potent than the known inhibitor C646,
providing natural product-derived compounds for further structural
optimization. Overall, this study will aid further efforts to explore
structurally unique palmatine and berberine derivatives and to
develop drug-like p300 HAT specific inhibitors.
Synthesis of palmatine derivatives
3-(3,4-Dimethoxyphenyl)acrylic acid (2a)
The compound 2a was prepared according to a procedure of Manral
et al [10a]. 18.8 g (180.6 mmol) of malonic acid was added to stirred
solution of the 3,4-dimethoxybenzaldehyde 1a (90.3 mmol) in
pyridine (150 mL) and piperidine (9.0 mL). The mixture was heated
to temperature of 115 ℃ for 2 h under reflux. After cooling, the
mixture was poured into cold water and acidified with 2 mol*L-1
hydrochloric acid in an ice bath. The precipitated pale pink crystals
2a were filtered, washed with cooled water and dried at 45 ℃, which
was used in the next step without further purification. 2a: yield 75.5%,
pale pink solid, m.p. = 181 - 183 ℃.
Experimental Section
3-(3,4-Dimethoxyphenyl)propanoic acid (3a)
General Experimental Procedures
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The compound 3a was prepared according to a modified procedure
of Haadsma-Svensson et al [10b]. In a heat gun dried 250 mL Schlenk
flask, equipped with a balloon with hydrogen, was placed 10% Pd/C
(1.5 g, 10 mol%) under hydrogen atmosphere. A warm ethanol
solution of dimethoxyphenylpropenoic acid 2a (14.0 g, 67.2 mmol)
was added and the mixture was stirred at rt for 16 h and then filtered
over Celite. The solvent was removed under reduced pressure to
afford compound 3a (11.1 g) as a white solid, which was used
without further purification in the next step. 3a: yield 78.7%, white
solid, m.p. = 95 - 97 ℃.
diluted with EtOAc (30 mL) and water (15 mL). The organic layer
was separated and the aqueous layer was washed two times with
EtOAc (20 mL). The combined organic layer was dried over Na2SO4
and concentrated under reduced pressure to afford compound 6a.
6a was used without further purification in the next step. 6a: Dark
brown oil.
3-(2-Ethynyl-4,5-dimethoxyphenyl)propan-1-ol (7a)
Compound 6a (7 g, 21.7 mmol) and TBAF (567 mg, 2.2 mmol) was
added in THF (150 mL) at room temperature for 30 min. Then the
solvent was removed under reduced pressure, the residue was
purified by silica gel flash column chromatography (petroleum
ether/acetone = 8:1) to afforded compound 7a (4.3 g) as a yellowish
white solid. 7a: yield 88.7%, yellowish white solid, m.p. = 80 – 82 ℃;
3-(3,4-Dimethoxyphenyl)propan-1-ol (4a)
NaBH4 (5.9 g, 157.0 mmol) was added to compound 3a (11.0 g, 52.3
mmol) in THF (80 mL) portionwise at room temperature. Then a
solution of I2 (13.3 g, 52.3 mmol) dissolved in THF (40 mL) was
added dropwise over 30 min. After the addition of I2 was completed
1H NMR (400 MHz, DMSO-d6) δ 6.94 (s, 1H), 6.83 (s, 1H), 4.49 (br s,
1H), 4.16 (s, 1H), 3.76 (s, 3H), 3.72 (s, 3H), 3.42 (t, J = 6.4 Hz, 2H),
2.68 (t, J = 7.6 Hz, 2H), 1.70 (p, J = 7.6 Hz, 2H).13C NMR (100 MHz,
DMSO-d6) δ 149.86, 146.99, 138.46, 115.54, 112.88, 112.78, 82.94,
82.64, 60.81, 56.05, 55.93, 34.20, 30.57.
and gas evolution had ceased, the reaction was heated to 60 ℃ and
stirred for another 10 h. After the reaction was completed as
monitored by TLC, methanol (30 mL) was added cautiously at 0 ℃.
6-((2-(3-Hydroxypropyl)-4,5-dimethoxyphenyl)ethynyl)-2,3-
Then the mixture was pour to H2O (200 mL), extracted with DCM (80
mL×3). The organic layers were combined, washed with brine, dried
over anhydrous Na2SO4 and concentrated under reduced pressure.
The residue was purified by silica gel column chromatography
(petroleum ether/ethyl acetate = 12:1) to give compound 4a as a
dimethoxybenzaldehyde (9a)
The compound 9a was prepared according to a procedure of Reddy
et al [12].Triethylamine (25 mL) was added to
a mixture of
PdCl2(PPh3)2 (80.0 mg, 0.12 mmol), CuI (10.4 mg, 0.054 mmol), 7a
(1.0 g, 4.5 mmol) and 6-bromo-2,3-dimethoxybenzaldehyde 8 (1.2 g,
4.9 mmol) under an inert atmosphere. The reaction mixture was
heated to 70 ℃ for 3 h. After the completion of the reaction
(monitored by TLC), Et3N was removed under reduced pressure.
The residue was then diluted with EtOAc (50 mL) and water (25 mL).
The organic layer was separated and the aqueous layer was washed
two times with EtOAc (50 mL). The combined organic layer was
dried over anhydrous Na2SO4, filtered and concentrated under
reduced pressure. The residue was purified by silica gel column
chromatography (petroleum ether/ethyl acetate = 3:1) to obtain pure
1
pale yellow oil. 4a: yield 88.6 %, pale yellow oil; H NMR (400 MHz,
DMSO-d6) δ 6.82 (d, J = 8.0 Hz, 1H), 6.77 (d, J = 2.0 Hz, 1H), 6.67
(dd, J = 8.0, 2.0 Hz, 1H), 4.44 (t, J = 5.2 Hz, 1H), 3.72 (s, 3H), 3.69
(s, 3H), 3.43 – 3.36 (m, 2H), 2.56 – 2.49 (m, 2H), 1.72 – 1.63 (m,
2H).
3-(2-Iodo-4,5-dimethoxyphenyl)propan-1-ol (5a)
Compound 5a was prepared according to the general procedure of
He et al [11]. Compound 4a (17.0 g, 86.6 mmol), I2 (29.2 g, 113.9
mmol), CF3COOAg (27.7 g, 123.5 mmol) were added in CHCl3 (200
mL) stirred at room temperature for 30 min. Then the solvent was
removed under reduced pressure, residue was purified by silica gel
column chromatography (petroleum ether/acetone = 12:1) afforded
compound 5a (25.1 g) as a pale yellow solid. 5a: yield 90.0%, Pale
1
9a. 9a: Yield 62.9%, yellow oil; H NMR (400 MHz, Chloroform-d) δ
10.56 (s, 1H), 7.37 (d, J = 8.4 Hz, 1H), 7.10 (d, J = 8.4 Hz, 1H), 7.03
(s, 1H), 6.75 (s, 1H), 3.95 (s, 3H), 3.93 (s, 3H), 3.91 - 3.89 (m, 6H),
3.73 (t, J = 6.0 Hz, 2H), 3.06 – 2.96 (m, 2H), 2.28 (br s, 1H), 2.02 –
1.92 (m, 2H).13C NMR (100 MHz, Chloroform-d) δ 190.68, 152.90,
152.00, 149.80, 146.95, 138.30, 130.17, 129.76, 117.16, 116.21,
114.83, 114.24, 111.88, 92.41, 89.32, 62.35, 56.22, 56.12, 55.98,
34.34, 30.79.
1
yellow solid, m.p. = 106 - 108 ℃; H NMR (600 MHz, DMSO-d6) δ
7.23 (s, 1H), 6.90 (s, 1H), 4.51 (t, J = 5.4 Hz, 1H), 3.74 (s, 3H), 3.72
(s, 3H), 3.46 – 3.41 (m, 2H), 2.63 – 2.59 (m, 2H), 1.69 – 1.61 (m,
2H).
3-(4,5-Dimethoxy-2-((trimethylsilyl)ethynyl)phenyl)propan-1-ol (6a)
2-((2-(3-Hydroxypropyl)-4,5-dimethoxyphenyl)ethynyl)-4,5-
dimethoxybenzaldehyde (9a’)
Compound 5a (6.6 g, 20.5 mmol), trimethylsilylacetylene (4.0 mL,
30.7 mmol), PdCl2(PPh3)2 (230.2 mg, 0.33 mmol), CuI (42.9 mg,
The compound 9a’ was prepared according to the procedure of
compound 9a with 7a and 2-bromo-4,5-dimethoxybenzaldehyde 8’.
9a’: Yield 65.3%, Pale yellow solid, m.p. = 148 – 149 ℃; 1H NMR
0.226 mmol) was added in 100 mL Et3N at 50 ℃ for 5 h. Then the
solvent was removed under reduced pressure and the residue was
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
(400 MHz, Chloroform-d) δ 10.50 (s, 1H), 7.40 (s, 1H), 7.07 (s, 1H),
7.01 (s, 1H), 6.77 (s, 1H), 3.99 (s, 3H), 3.95 (s, 3H), 3.91 (s, 3H),
3.90 (s, 3H), 3.72 (t, J = 6.0 Hz, 2H), 2.96 – 2.88 (m, 2H), 1.97 –
1.92 (m, 2H).13C NMR (100 MHz, Chloroform-d) δ 190.73, 153.83,
150.01, 149.57, 147.07, 138.07, 129.80, 122.18, 114.54, 114.29,
113.44, 112.03, 108.36, 94.25, 87.23, 62.18, 56.42, 56.21, 56.14,
56.01, 34.11, 31.00.
monitored by TLC, the mixture was diluted with 20 mL CH2Cl2. The
CH2Cl2 layer was washed with brine, dried over anhydrous Na2SO4,
filtered and concentrated under reduced pressure. The residue was
purified by silica gel column chromatography (CH2Cl2/MeOH = 30:1)
to give compound 11a (826 mg) as a yellow solid. 11a: yield 85.2%,
1
yellow solid, m.p. = 168 - 170 ℃ (decomposed); H NMR (400 MHz,
DMSO-d6) δ 10.08 (s, 1H), 8.63 (s, 1H), 8.26 (d, J = 8.8 Hz, 1H),
8.10 (d, J = 8.8 Hz, 1H), 7.31 (s, 1H), 7.11 (s, 1H), 5.05 (br s, 1H),
4,25 – 4.17 (br s, 1H), 4.12 (d, J = 1.7 Hz, 3H), 4.09 (s, 3H), 3.87 (s,
6H), 2.76 (br s, 1H), 2.66 (br s, 1H), 2.50 (br s, 1H), 2.32 (br s,
1H).13C NMR (100 MHz, DMSO-d6) δ 150.95, 150.59, 147.85,
145.82, 143.77, 143.67, 132.48, 131.38, 126.67, 125.44, 123.60,
123.21, 122.29, 113.48, 112.62, 61.98, 57.39, 57.15, 56.02, 55.84,
3-(2-(7,8-Dimethoxyisoquinolin-3-yl)-4,5-dimethoxyphenyl)propan-1-
ol (10a)
The compound 10a was prepared according to a procedure of
t
Reddy et al [12]. BuOH (100 mL) was added to a mixture of AgNO3
(60.3 mg, 0.36 mmol), ammonium acetate (410.0 mg, 5.3 mmol) and
9a (1.4g, 3.6 mmol) under an inert atmosphere. The resulting
mixture was stirred at room temperature for 10h and the reaction
was monitored by TLC. After completion, the reaction was quenched
by the addition of NaHCO3 (1.17 g, 13.9 mmol) at room temperature
and stirring was continued for additional 5 h. The mixture was then
filtered through a cotton plug, washed with EtOAc (50 mL) and dried
over anhydrous Na2SO4. The filtrate was evaporated under reduced
pressure and the residue was purified through silica gel column
chromatography (petroleum ether/ethyl acetate = 1:1) to obtain the
pure isoquinoline 10a (796 mg). 10a: Yield: 61.1%, pale yellow solid,
+
31.37, 27.76. LC-MS (ESI): m/z calculated for C22H24NO4 [M-
- +
CH3SO3 ] : 366.2, found: 366.2.
2,3,11,12-Tetramethoxy-6,7-dihydro-5H-benzo[3,4]azepino[1,2-
b]isoquinolin-8-ium methanesulfonate (12a)
The compound 12a was prepared according to the procedure for
preparing compound 11a. 12a: yield 83.4%, pale yellow solid, m.p. =
122 – 123 ℃; 1H NMR (400 MHz, DMSO-d6) δ 9.76 (s, 1H), 8.41 (s,
1H), 7.75 (s, 1H), 7.74 (s, 1H), 7.29 (s, 1H), 7.11 (s, 1H), 4.73 (br s,
1H), 4.22 (br s, 1H), 4.07 (s, 3H), 4.02 (s, 3H), 3.87 (s, 6H), 2.77 (br
s, 1H), 2.60 (br s, 1H), 2.50 (br s, 1H), 2.33 (br s, 1H).13C NMR (100
MHz, Methanol-d4) δ 160.02, 154.71, 153.19, 150.04, 146.57,
146.26, 138.48, 132.98, 125.01, 124.92, 124.68, 114.40, 113.63,
107.46, 106.45, 58.34, 57.53, 57.11, 56.94, 56.66, 33.09, 29.40. LC-
1
m.p. = 109 – 110 ℃; H NMR (400 MHz, DMSO-d6) δ 9.43 (s, 1H),
7.83 (s, 1H), 7.77 (d, J = 9.2 Hz, 1H), 7.74 (d, J = 9.2 Hz, 1H), 7.01
(s, 1H), 6.91 (s, 1H), 4.50 (t, J = 5.2 Hz, 1H), 4.00 (s, 3H), 3.98 (s,
3H), 3.82 (s, 3H), 3.77 (s, 3H), 3.33 – 3.26 (m, 2H), 2.75 – 2.66 (m,
2H), 1.68 – 1.58 (m, 2H).13C NMR (101 MHz, DMSO-d6) δ 151.12,
148.54, 148.42, 146.57, 145.56, 142.66, 132.70, 132.19, 131.57,
123.09, 121.87, 120.80, 119.26, 113.94, 113.22, 61.31, 60.37, 56.87,
55.60, 48.51, 34.41, 30.14.
- +
MS (ESI): m/z calculated for C22H24NO4+ [M-CH3SO3 ] : 366.2, found:
366.2.
2,3,11-Trimethoxy-6,7-dihydro-5H-benzo[3,4]azepino[1,2-
b]isoquinolin-8-ium-10-olate (11a’)
3-(2-(6,7-Dimethoxyisoquinolin-3-yl)-4,5-dimethoxyphenyl)propan-1-
Compound 11a’ (268 mg, 0.58 mmol) was placed in the round
bottom flask and heated at 180 °C in vacuum for 2 h to give the
crude product, which was purified by silica gel column
chromatography (CH2Cl2/MeOH = 10:1) to give the compound 11a’
as a dark red solid (184 mg). 11a’: yield 90.6%, Dark red solid, m.p.
> 200 ℃; 1H NMR (400 MHz, DMSO-d6) δ 9.60 (s, 1H), 7.97 (s, 1H),
7.64 (d, J = 8.1 Hz, 1H), 7.22 (s, 1H), 7.11 – 6.91 (m, 2H), 4.74 (br s,
1H), 4.15 – 4.00 (m, 1H), 3.95 – 3.80 (m, 9H), 2.73 (br s, 1H), 2.60
(br s, 1H), 2.39 (br s, 1H), 2.17 (br s, 1H).
ol (10a’)
The compound 10a’ was prepared according to the procedure of
compound 10a. 10a’: yield 59.5%, Yellow oil, 1H NMR (400 MHz,
DMSO-d6) δ 9.09 (s, 1H), 7.71 (s, 1H), 7.50 (s, 1H), 7.37 (s, 1H),
6.97 (s, 1H), 6.89 (s, 1H), 4.55 (t, J = 4.8 Hz, 1H), 3.93 (s, 6H), 3.81
(s, 3H), 3.76 (s, 3H), 3.31 – 3.24 (m, 2H), 2.77 – 2.64 (m, 2H), 1.65 –
1.55 (m, 2H).13C NMR (100 MHz, DMSO-d6) δ 152.93, 151.70,
150.04, 148.30, 146.53, 132.66, 132.64, 132.60, 122.83, 118.72,
118.69, 113.87, 113.22, 105.40, 105.01, 60.34, 55.77, 55.68, 55.57,
48.51, 34.36, 30.15.
10-(Benzyloxy)-2,3,11-trimethoxy-6,7-dihydro-5H-benzo[3,4]
azepino[1,2-b]isoquinolin-8-ium chloride (13a)
2,3,10,11-Tetramethoxy-6,7-dihydro-5H-benzo[3,4]azepino[1,2-
(Chloromethyl)benzene (360.8 mg, 2.85 mmol) was added to
compound 11a’ (200 mg, 0.57 mmol) in 10 mL CH3CN at room
temperature. The resulting mixture was refluxed at 85 °C for 3 h.
After the reaction was completed as monitored by TLC, then the
mixture was concentrated under reduced pressure. The residue was
b]isoquinolin-8-ium methanesulfonate (11a)
Methanesulphonyl chloride (322 µl, 4.2 mmol) was added into the
solution of 10a (796 mg, 2.1 mmol) and triethylamine (865 µl, 6.3
mmol) in 100 mL CH2Cl2 at 0 °C. The resulting mixture was allowed
to warm to 50 °C for 5 h. After the reaction was completed as
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
purified by neutral Al2O3 column chromatography (dichloromethane
/CH3OH = 100:1) to give compound 13a (56.4 mg) as a yellow solid.
13a: yield 20.7%, yellow solid, m.p. = 78 – 79 ℃; 1H NMR (400 MHz,
DMSO-d6) δ 9.93 (s, 1H), 8.63 (s, 1H), 8.27 (d, J = 8.8 Hz, 1H), 8.12
(d, J = 8.8 Hz, 1H), 7.58 (d, J = 7.2 Hz, 2H), 7.50 – 7.23 (m, 4H),
7.10 (s, 1H), 5.39 (s, 2H), 5.06 (br s, 1H), 4.35 – 4.20 (m, 1H), 4.12
(s, 3H), 3.87 (s, 6H), 2.77 (br s, 1H), 2.62 (br s, 1H), 2.46 – 2.20 (m,
2H). 13C NMR (100 MHz, DMSO-d6) δ 151.03, 150.91, 147.83,
145.61, 143.44, 141.85, 136.28, 132.29, 131.22, 129.15, 128.47,
128.30, 126.36, 125.47, 123.94, 123.11, 122.88, 113.44, 112.59,
75.28, 57.39, 57.10, 56.01, 55.82, 31.42, 27.71. LC-MS (ESI): m/z
calculated for C28H28NO4+ [M-Cl-]+: 442.2, found: 442.1.
portionwise at 0 °C. The resulting mixture was refluxed at 65 °C for 3
h. After the reaction was completed as monitored by TLC, then the
mixture was concentrated and pour to H2O (10 mL), extracted with
DCM (15 mL×3). The organic layers were combined, washed with
brine, dried over anhydrous Na2SO4 and concentrated under
reduced pressure to give compound 15a’ (208 mg) as pale yellow oil
which was used in the next step without further purification.
8-Benzyl-2,3,10,11-tetramethoxy-6,7,8,9,14,14a-hexahydro-5H-
benzo[3,4]azepino[1,2-b]isoquinolin-8-ium bromide (16a)
Benzyl bromide (484 mg, 2.83 mmol) was added to compound 15a
(221 mg) in 10 mL CH3CN at room temperature. The resulting
mixture was stirred at 50 °C for 3 h. After the reaction was
completed as monitored by TLC, then the mixture was concentrated
under reduced pressure. The residue was purified by silica gel
column chromatography (dichloromethane /CH3OH = 50:1) to give
and to give compound 16a (218.2 mg) as a cream white solid. 16a:
2,3,11-Trimethoxy-10-((4-nitrobenzyl)oxy)-6,7-dihydro-5H-
benzo[3,4]azepino[1,2-b]isoquinolin-8-ium bromide (14a)
1-(Bromomethyl)-4-nitrobenzene (616 mg, 2.85 mmol) was added to
compound 11a’ (200 mg, 0.57 mmol) in 10 mL CH3CN at room
temperature. The resulting mixture was refluxed at 85 °C for 3 h.
After the reaction was completed as monitored by TLC, then the
mixture was concentrated under reduced pressure. The residue was
purified by neutral Al2O3 column chromatography (dichloromethane
/CH3OH = 100:1) to give compound 14a (54.3 mg) as a yellow solid.
14a: yield 18.2%, yellow solid, m.p. = 185 – 186 ℃, 1H NMR (400
MHz, DMSO-d6) δ 10.04 (s, 1H), 8.65 (s, 1H), 8.28 (d, J = 8.4 Hz,
3H), 8.15 (d, J = 8.4 Hz, 1H), 7.91 (d, J = 8.4 Hz, 2H), 7.32 (s, 1H),
7.11 (s, 1H), 5.53 (s, 2H), 5.06 (br s, 1H), 4.20 (br s, 1H), 4.09 (s,
3H), 3.92 – 3.82 (m, 6H), 2.77 (s, 1H), 2.67 (s, 1H), 2.46 (s, 1H),
2.33 (s, 1H). 13C NMR (100 MHz, DMSO-d6) δ 150.97, 150.75,
147.86, 147.26, 145.63, 144.40, 143.72, 141.74, 132.42, 131.36,
129.39, 126.40, 125.54, 124.22, 123.52, 123.14, 122.54, 113.46,
112.62, 74.05, 57.53, 57.17, 56.03, 55.86, 31.44, 27.75. LC-MS
(ESI): m/z calculated for C28H27N2O6+ [M-Br-]+: 487.2, found: 487.2.
1
yield 82.1%, cream white solid, m.p. = 152 – 154 ℃; H NMR (400
MHz, DMSO-d6) δ 7.66 (d, J = 6.8 Hz, 2H), 7.58 – 7.45 (m, 3H), 7.25
(s, 1H), 7.11 (d, J = 8.8 Hz, 1H), 7.07 – 6.94 (m, 2H), 5.46 (dd, J =
13.2, 6.8 Hz, 1H), 5.23 (d, J = 15.2 Hz, 1H), 4.88 (d, J = 13.2 Hz,
1H), 4.56 (d, J = 13.2 Hz, 1H), 3.94 (d, J = 15.2 Hz, 2H), 3.86 – 3.73
(m, 9H), 3.71 – 3.64 (m, 1H), 3.61 (s, 3H), 3.49 – 3.41 (m, 1H), 3.30
– 3.16 (m, 2H), 2.94 – 2.82 (m, 1H), 2.67 – 2.52 (m, 1H), 2.06 (d, J =
13.2 Hz, 1H). 13C NMR (100 MHz, DMSO-d6) δ 150.66, 148.98,
146.88, 144.87, 133.49, 132.86, 130.38, 128.96, 127.69, 124.07,
123.71, 123.07, 120.42, 115.99, 115.22, 113.41, 73.58, 61.57, 60.00,
59.42, 55.98, 55.72, 55.66, 54.94, 32.06, 28.94, 22.82. LC-MS (ESI):
m/z calculated for C29H34NO4+ [M-Br-]+: 460.2, found: 460.1.
8-Benzyl-2,3,11,12-tetramethoxy-6,7,8,9,14,14a-hexahydro-5H-
benzo[3,4]azepino[1,2-b]isoquinolin-8-ium bromide (17a)
The compound 17a was prepared according to the procedure of
compound 16a. 17a: yield 84.6%, cream white solid, m.p. = 219 –
221 ℃; 1H NMR (400 MHz, DMSO-d6) δ 7.72 – 7.59 (m, 2H), 7.56 –
7.48 (m, 3H), 7.30 (s, 1H), 7.00 (s, 1H), 6.87 (s, 1H), 6.78 (s, 1H),
5.50 (dd, J = 13.2, 4.8 Hz, 1H), 5.21 (d, J = 14.8 Hz, 1H), 4.84 (d, J
= 13.2 Hz, 1H), 4.50 (d, J = 13.2 Hz, 1H), 3.87 (d, J = 14.8 Hz, 2H),
3.81 (s, 3H), 3.79 (s, 3H), 3.74 (s, 3H), 3.73 – 3.71 (m, 1H), 3.69 (s,
3H), 3.46 – 3.39 (m, 1H), 3.26 – 3.14 (m, 2H), 2.96 – 2.84 (m, 1H),
2.66 – 2.52 (m, 1H), 2.09 (d, J = 14.8 Hz, 1H). 13C NMR (100 MHz,
DMSO-d6) δ 148.91, 148.61, 147.98, 146.87, 133.43, 132.88, 130.21,
128.98, 127.68, 123.94, 122.34, 118.25, 116.04, 115.16, 111.21,
110.32, 73.99, 63.24, 61.23, 55.74, 55.63, 55.54, 54.39, 32.19,
2,3,10,11-Tetramethoxy-5,6,7,9,14,14a-hexahydrobenzo[3,4]
azepino[1,2-b]isoquinoline (15a)
NaBH4 (74.1 mg, 1.96 mmol) was added to compound 11a (226 mg,
0.49 mmol) and K2CO3 (62 mg, 0.49 mmol) in CH3OH (10 mL)
portionwise at 0 °C. The resulting mixture was refluxed at 65 °C for 3
h. After the reaction was completed as monitored by TLC, then the
mixture was concentrated and pour to H2O (10 mL), extracted with
DCM (15 mL×3). The organic layers were combined, washed with
brine, dried over anhydrous Na2SO4 and concentrated under
reduced pressure to give compound 15a (221 mg) as pale yellow oil
which was used in the next step without further purification.
29.62, 22.85. LC-MS (ESI): m/z calculated for C29H34NO4 [M-Br-]+:
+
2,3,11,12-Tetramethoxy-5,6,7,9,14,14a-hexahydrobenzo[3,4]
460.2, found: 460.1.
azepino[1,2-b]isoquinoline (15a’)
Synthesis of berberine derivatives
3-(Benzo[d][1,3]dioxol-5-yl)acrylic acid (2b)
NaBH4 (74.1 mg, 1.96 mmol) was added to compound 12a (226 mg,
0.49 mmol) and K2CO3 (62 mg, 0.49 mmol) in CH3OH (10 mL)
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
The compound 2b was prepared according to the literature
procedure of Yang et al [20]. 16.6 g (159.9 mmol) of malonic acid was
added to stirred solution of the benzo[d][1,3]dioxole-5-carbaldehyde
1b (79.9 mmol) in pyridine (140 mL) and piperidine (7.2 mL). The
mixture was heated to temperature of 115 ℃ for 2 h under reflux.
After cooling, the mixture was poured into cold water and acidified
with 2 mol*L-1 hydrochloric acid in an ice bath. The precipitated white
crystals 2b were filtered, washed with cooled water and dried at
45 ℃, which was used in the next step without further purification.
2.77 – 2.70 (m, 2H), 1.93 (s, 1H), 1.86 – 1.77 (m, 2H).
3-(6-((Trimethylsilyl)ethynyl)benzo[d][1,3]dioxol-5-yl)propan-1-ol (6b)
Compound 5b (4.24 g, 13.9 mmol), trimethylsilylacetylene (2.95 mL,
20.9 mmol), PdCl2(PPh3)2 (155.5 mg, 0.22 mmol), CuI (29 mg, 0.15
mmol) was added in 35 mL Et3N at 50 °C for 5 h. Then the solvent
was removed under reduced pressure and the residue was diluted
with EtOAc (30 mL) and water (15 mL). The organic layer was
separated and the aqueous layer was washed two times with EtOAc
(20 mL). The combined organic layer was dried over Na2SO4 and
concentrated under reduced pressure. The crude product was
purified by silica gel column chromatography (petroleum
ether/EtOAc = 5:1) to afford compound 6b as yellow oil (2.7 g). 6b:
2b: yield 77.2%, pale white solid, m.p. > 200 ℃.
3-(Benzo[d][1,3]dioxol-5-yl)propanoic acid (3b)
In a heat gun dried 250 mL Schlenk flask, equipped with a balloon
with hydrogen, was placed 10% Pd/C (1.2 g, 10 mol%) under
1
yield 74.2%, yellow oil; H NMR (400 MHz, Chloroform-d) δ 6.87 (s,
1H), 6.66 (s, 1H), 5.93 (s, 2H), 3.60 (t, J = 6.4 Hz, 2H), 2.81 (t, J =
7.2 Hz, 2H), 1.98 (s, 1H), 1.89 – 1.80 (m, 2H), 0.24 (s, 9H).
hydrogen
atmosphere.
A
warm
ethanolic
solution
of
dimethoxyphenylpropenoic acid 2b (12.0 g, 62.4 mmol) was added
and the mixture was stirred at rt for 16 h and then filtered over Celite.
The solvent was removed under reduced pressure to afford
compound 3b (9.0 g) as a white solid, which was used without
further purification in the next step. 3b: yield 74.3%, white solid, m.p.
= 82 - 84 ℃.
3-(6-Ethynylbenzo[d][1,3]dioxol-5-yl)propan-1-ol (7b)
Compound 6b (2.23 g, 8.46 mmol) and TBAF (222 mg, 0.85 mmol)
in THF (20 mL) at room temperature for 30 min. Then the solvent
was removed under reduced pressure and the residue was diluted
with EtOAc (30 mL) and 1M HCl (50 mL). The organic layer was
separated and the aqueous layer was washed two times with EtOAc
(20 mL). The combined organic layer was dried over Na2SO4 and
concentrated under reduced pressure to afford compound 7b (1.7g).
7b was used without further purification in the next step. 7b: yield
98.3%, yellow oil.
3-(Benzo[d][1,3]dioxol-5-yl)propan-1-ol (4b)
NaBH4 (7.58 g, 202 mmol) was added to compound 3b (13.1 g, 67.6
mmol) in 80 mL THF portionwise at 0 ℃. Then a solution of I2 (17.0
g, 67.6 mmol) dissolved in THF (180 mL) was added dropwise over
30 min. After the addition of I2 was completed and gas evolution had
ceased, the reaction was heated to 60 ℃ and stirred for another 4 h.
After the reaction was completed as monitored by TLC, 26 mL
methanol was added cautiously at 0 ℃. Then the mixture was pour
to 200 mL H2O, extracted with DCM (80 mL × 3). The organic layers
were combined, washed with brine, dried over anhydrous Na2SO4
and concentrated under reduced pressure to give compound (16.7 g)
as yellow oil which was used in the next step without further
6-((6-(3-Hydroxypropyl)benzo[d][1,3]dioxol-5-yl)ethynyl)-2,3-
dimethoxybenzaldehyde (9b)
The compound 9b was prepared according to the procedure of
compound 9a. Triethylamine (25 mL) was added to a mixture of
PdCl2(PPh3)2 (98.3 mg, 0.14 mmol), CuI (13.3 mg, 0.07 mmol), 7b
(1.36 g, 5.6 mmol) and 6-bromo-2,3-dimethoxybenzaldehyde 8 (1.47
g, 7.2 mmol) under an inert atmosphere. The reaction mixture was
heated to 70 ℃ for 3 h. After the completion of the reaction
(monitored by TLC), Et3N was removed under reduced pressure.
The residue was then diluted with EtOAc (50 mL) and water (25 mL).
The organic layer was separated and the aqueous layer was washed
two times with EtOAc (50 mL). The combined organic layer was
dried over anhydrous Na2SO4, filtered and concentrated under
reduced pressure. The residue was purified by silica gel column
chromatography (petroleum ether/ethyl acetate = 3:1) to obtain pure
9b(1.43g). 9b: Yield 70.3%, yellow oil; 1H NMR (400 MHz,
Chloroform-d) δ 10.53 (s, 1H), 7.32 (d, J = 8.4 Hz, 1H), 7.07 (d, J =
8.4 Hz, 1H), 6.96 (s, 1H), 6.71 (s, 1H), 5.94 (s, 2H), 3.94 (s, 3H),
3.90 (s, 3H), 3.71 (t, J = 6.0 Hz, 2H), 2.98 (t, J = 7.6 Hz, 2H), 2.63
(br s, 1H), 1.97 – 1.88 (m, 2H).
1
purification. 4b: yellow oil; H NMR (400 MHz, Chloroform-d) δ 6.72
(d, J = 7.6 Hz, 1H), 6.69 (d, J = 2.4 Hz, 1H), 6.63 (dd, J = 7.6, 2.4 Hz,
1H), 5.90 (s, 2H), 3.63 (t, J = 6.4 Hz, 2H), 2.61 (t, J = 7.6 Hz, 2H),
2.51 (s, 1H), 1.88 – 1.78 (m, 2H).
3-(6-Iodobenzo[d][1,3]dioxol-5-yl)propan-1-ol (5b)
Compound 5b was prepared according to the general procedure of
He et al [11].Compound 4b (12.3 g, 68.6 mmol), I2 (21.1 g, 82.3 mmol),
CF3COOAg (20 g, 89.2 mmol) was added in CHCl3 (200 mL) stirred
at -5 °C to room temperature for 30 min. Then the solvent was
removed under reduced pressure, the residue was purified by silica
gel column chromatography (petroleum ether/acetone
= 12:1)
afforded compound (17.7 g) as a light yellow solid. 5b: yield 84.2%,
light yellow solid, m.p. = 28 - 30 ℃; 1H NMR (400 MHz, Chloroform-d)
δ 7.22 (s, 1H), 6.76 (s, 1H), 5.94 (s, 2H), 3.70 (t, J = 6.4 Hz, 2H),
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
2-((6-(3-Hydroxypropyl)benzo[d][1,3]dioxol-5-yl)ethynyl)-4,5-
The compound 11b was prepared according to the procedure of
compound 11a. 11b: yield 87.3%, yellow solid, m.p. = 106 – 108 ℃;
1H NMR (400 MHz, DMSO-d6) δ 10.08 (s, 1H), 8.55 (s, 1H), 8.25 (d,
J = 8.8 Hz, 1H), 8.10 (d, J = 8.8 Hz, 1H), 7.29 (s, 1H), 7.08 (s, 1H),
6.16 (s, 2H), 5.05 (br s, 1H), 4.22 (br s, 1H), 4.12 (s, 3H), 4.08 (s,
3H), 2.74 (br s, 1H), 2.64 (br s, 1H), 2.42 (br s, 1H), 2.30 (br s, 1H).
13C NMR (100 MHz, DMSO-d6) δ 150.71, 149.49, 146.71, 145.92,
143.79, 143.25, 133.17, 132.39, 126.64, 125.60, 124.58, 123.70,
122.37, 109.99, 109.49, 101.96, 61.99, 57.16, 31.27, 27.91. LC-MS
dimethoxybenzaldehyde (9b’)
The compound 9b’ was prepared according to the procedure of
compound 9b with 7b and 2-bromo-4,5-dimethoxybenzaldehyde 8’.
9b’: Yield 68.6%, light yellow solid, m.p. = 164 – 166 ℃; 1H NMR
(400 MHz, DMSO-d6) δ 10.36 (s, 1H), 7.31 (s, 1H), 7.24 (s, 1H), 7.14
(s, 1H), 6.91 (s, 1H), 6.05 (s, 2H), 4.58 (t, J = 5.6 Hz, 1H), 3.90 (s,
3H), 3.85 (s, 3H), 3.46 (q, J = 5.6 Hz, 2H), 2.84 – 2.76 (m, 2H), 1.78
– 1.68 (m, 2H). 13C NMR (100 MHz, DMSO-d6) δ 189.71, 153.65,
149.36, 148.34, 145.41, 140.05, 128.99, 120.87, 114.73, 113.65,
111.17, 109.46, 108.12, 101.52, 93.65, 87.30, 60.27, 56.15, 55.67,
34.12, 30.86.
+
- +
(ESI): m/z calculated for C21H20NO4 [M-CH3SO3 ] : 350.1, found:
350.1.
11,12-Dimethoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo
[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium methanesulfonate (12b)
3-(6-(7,8-Dimethoxyisoquinolin-3-yl)benzo[d][1,3]dioxol-5-yl)propan-
1-ol (10b)
The compound 12b was prepared according to the procedure of
compound 11b. 12b: yield 85.3%, yellow solid, m.p. = 136 – 138 ℃;
1H NMR (400 MHz, DMSO-d6) δ 9.89 (s, 1H), 8.37 (s, 1H), 7.80 (s,
1H), 7.76 (s, 1H), 7.25 (s, 1H), 7.07 (s, 1H), 6.16 (s, 2H), 4.79 (br s,
1H), 4.18 (br s, 1H), 4.06 (s, 3H), 4.01 (s, 3H), 2.74 (br s, 1H), 2.56
(br s, 1H), 2.28 (s, 2H). 13C NMR (100 MHz, DMSO-d6) δ 162.63,
157.49, 154.62, 151.88, 151.01, 149.12, 141.29, 138.19, 129.88,
128.65, 128.03, 114.85, 114.68, 111.85, 110.92, 107.11, 62.03,
61.61, 61.57, 36.50, 33.10. LC-MS (ESI): m/z calculated for
The compound 10b was prepared according to the procedure of
t
compound 10a. BuOH (36 mL) was added to a mixture of AgNO3
(63.0 mg, 0.37 mmol), ammonium acetate (429.0 mg, 5.6 mmol) and
9b (1.4g, 3.7 mmol) under an inert atmosphere. The resulting
mixture was stirred at room temperature for 10h and the reaction
was monitored by TLC. After completion, the reaction was quenched
by the addition of NaHCO3 (1.17 g, 13.9 mmol) at room temperature
and stirring was continued for additional 5 h. The mixture was then
filtered through a cotton plug, washed with EtOAc (50 mL) and dried
over anhydrous Na2SO4. The filtrate was evaporated under reduced
pressure and the residue was purified through silica gel column
chromatography (petroleum ether/ethyl acetate = 1:1) to obtain the
pure isoquinoline 10b (1.07 g). 10b: Yield: 78.5%, yellow foamed
solid, m.p. = 45 – 46 ℃; 1H NMR (400 MHz, Chloroform-d) δ 9.61 (s,
1H), 7.70 (s, 1H), 7.63 (d, J = 8.8 Hz, 1H), 7.60 (d, J = 8.8 Hz, 1H),
6.86 (s, 1H), 6.83 (s, 1H), 6.01 (s, 2H), 4.11 (s, 3H), 4.04 (s, 3H),
3.65 – 3.57 (m, 2H), 2.75 (t, J = 6.8 Hz, 2H), 2.00 – 1.92 (m, 2H).13C
NMR (100 MHz, DMSO-d6) δ 150.98, 148.67, 146.98, 145.63,
145.26, 142.72, 134.31, 133.47, 131.57, 123.14, 121.97, 120.89,
119.49, 110.14, 109.55, 101.01, 61.34, 60.28, 56.92, 34.27, 28.96.
- +
C21H20NO4+ [M-CH3SO3 ] : 350.1, found: 350.1.
10,11-Dimethoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo
[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium hydroxide (11b’)
The compound 11b’ was prepared according to the literature
procedure of Wang et al [13]. CaO was added to the compound 11b
(80 mg, 0.18 mmol) dissolved in methanol (5 mL) and water (1 mL)
portionwise to adjust pH to 9-10, the suspension was then stirred at
60 °C for 3 h. The resulting mixture was pour to H2O (10 mL),
extracted with DCM (10 mL × 4). The organic layers were combined,
washed with brine, dried over anhydrous Na2SO4 and concentrated
under reduced pressure. Crude product was used in the next step
without further purification.
3-(6-(6,7-Dimethoxyisoquinolin-3-yl)benzo[d][1,3]dioxol-5-yl)propan-
10,11-Dimethoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo
1-ol (10b’)
[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium chloride (13b)
The compound 10b’ was prepared according to the procedure of
compound 10b. 10b’: yield 74.1%, yellow oil; 1H NMR (400 MHz,
DMSO-d6) δ 9.08 (s, 1H), 7.66 (s, 1H), 7.49 (s, 1H), 7.34 (s, 1H),
6.92 (s, 1H), 6.89 (s, 1H), 6.03 (s, 2H), 3.92 (s, 6H), 3.26 (t, J = 6.4
Hz, 2H), 2.65 (t, J = 7.6 Hz, 2H), 1.91 (s, 1H), 1.62 – 1.52 (m, 2H).
13C NMR (100 MHz, DMSO-d6) δ 152.96, 151.48, 150.11, 148.82,
146.81, 145.17, 134.13, 133.91, 132.59, 122.90, 118.82, 110.04,
109.48, 105.42, 105.00, 100.94, 60.21, 55.78, 55.70, 34.20, 28.88.
The crude 11b’ was then dissolved in 5 mL dichloromethane, and
the solution of HCl in ethyl acetate was added. The resulting mixture
was stirred at room temperature for 1 h, and filtered to afford
compound 13b as a yellow solid. 13b: yield 35.7%, yellow solid, m.p.
= 116 – 118 ℃; 1H NMR (400 MHz, Methanol-d4) δ 9.95 (s, 1H), 8.38
(s, 1H), 8.17 (d, J = 8.8 Hz, 1H), 8.04 (d, J = 8.8 Hz, 1H), 7.22 (s,
1H), 6.96 (s, 1H), 6.10 (s, 2H), 4.98 – 4.93 (m, 1H), 4.41 (br s, 1H),
4.23 (s, 3H), 4.13 (s, 3H), 2.80 (br s, 2H), 2.43 (br s, 2H). 13C NMR
(100 MHz, Methanol-d4) δ 150.94, 150.45, 147.61, 145.32, 144.52,
144.09, 133.12, 126.59, 125.41, 124.56, 123.10, 122.84, 109.50,
10,11-Dimethoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo
[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium methanesulfonate (11b)
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
109.10, 102.11, 61.20, 57.58, 56.27, 31.59, 28.15. LC-MS (ESI): m/z
calculated for C21H20NO4+ [M-Cl-]+: 350.1, found: 350.1.
3H), 2.75 (br s, 1H), 2.62 (br s, 1H), 2.42 (br s, 1H), 2.29 (br s, 1H).
13C NMR (100 MHz, Methanol-d4) δ 152.16, 151.91, 149.04, 146.60,
145.57, 144.02, 134.55, 134.49, 127.68, 126.89, 125.89, 124.96,
124.33, 110.90, 110.51, 103.53, 75.24, 59.24, 57.64, 44.53, 33.04,
29.51. LC-MS (ESI): m/z calculated for C22H21BrNO4+ [M-Br-]+: 442.1,
found: 442.0.
11-Methoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo[1',2':3,4]
azepino[1,2-b]isoquinolin-8-ium-10-olate (14b)
The compound 14b was prepared according to the procedure of
1
compound 11a’. 14b: yield 95.1%, dark red solid, m.p. > 220 ℃; H
10-(Benzyloxy)-11-methoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']
NMR (400 MHz, DMSO-d6) δ 9.29 (s, 1H), 7.57 (s, 1H), 7.31 (d, J =
8.0 Hz, 1H), 7.16 (s, 1H), 6.97 (s, 1H), 6.49 (d, J = 8.0 Hz, 1H), 6.10
(s, 2H), 4.57 (br s, 1H), 3.88 (br s, 1H), 3.75 (s, 3H), 2.69 (br s, 1H),
2.40 (br s, 2H), 2.04 (br s, 1H). 13C NMR (100 MHz, DMSO-d6) δ
149.42, 148.58, 146.46, 145.94, 139.65, 132.24, 131.57, 126.11,
122.47, 122.44, 121.60, 121.55, 120.63, 109.27, 102.42, 101.59,
55.89, 53.96, 30.20, 28.40.
benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium
chloride
(17b)
(Chloromethyl)benzene (360.8 mg, 2.85 mmol) was added to
compound 14b (191.2 mg, 0.57 mmol) in 10 mL CH3CN at room
temperature. The resulting mixture was refluxed at 85 °C for 3 h.
After the reaction was completed as monitored by TLC, then the
mixture was concentrated under reduced pressure. The residue was
purified by neutral Al2O3 column chromatography (dichloromethane
/CH3OH = 100:1) to give compound 17b (49.2 mg) as a yellow solid.
17b: yield 18.7%, yellow solid, m.p. = 60 – 72 ℃, 1H NMR (400 MHz,
DMSO-d6) δ 9.87 (s, 1H), 8.51 (s, 1H), 8.27 (d, J = 9.2 Hz, 1H), 8.08
(d, J = 9.2 Hz, 1H), 7.56 (d, J = 7.2 Hz, 2H), 7.41 – 7.32 (m, 3H),
7.30 (s, 1H), 7.08 (s, 1H), 6.16 (s, 2H), 5.38 (d, J = 4.8 Hz, 2H), 5.00
(br s, 1H), 4.21 (br s, 1H), 4.11 (s, 3H), 2.75 (br s, 1H), 2.57 (br s,
1H), 2.28 (br s, 2H). 13C NMR (100 MHz, Methanol-d4) δ 153.00,
151.88, 149.03, 146.44, 145.27, 143.82, 137.67, 134.35, 134.28,
130.50, 129.89, 129.62, 127.59, 126.77, 125.80, 125.12, 124.94,
110.79, 110.48, 103.52, 76.95, 58.92, 57.59, 33.01, 29.43. LC-MS
(ESI): m/z calculated for C27H24NO4+ [M-Cl-]+: 426.2, found: 426.2.
10-Butoxy-11-methoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']benzo
[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide (15b)
1-Bromobutane (390.5 mg, 2.85 mmol) was added to compound 14b
(191.2 mg, 0.57 mmol) in 10 mL CH3CN at room temperature. The
resulting mixture was refluxed at 85 ℃ for 3 h. After the reaction was
completed as monitored by TLC, then the mixture was concentrated
under reduced pressure. The residue was purified by neutral Al2O3
column chromatography (dichloromethane /CH3OH = 100:1) to give
compound 15b (62.4 mg) as a yellow solid. 15b: yield 23.2%, yellow
solid, m.p. = 182 – 183 ℃; 1H NMR (400 MHz, DMSO-d6) δ 9.96 (s,
1H), 8.56 (s, 1H), 8.25 (d, J = 9.2 Hz, 1H), 8.09 (d, J = 9.2 Hz, 1H),
7.30 (s, 1H), 7.08 (s, 1H), 6.16 (s, 2H), 5.10 (br s, 1H), 4.31 (br s,
2H), 4.22 (br s, 1H), 4.07 (s, 3H), 2.74 (br s, 1H), 2.63 (br s, 1H),
2.42 (br s, 1H), 2.27 (br s, 1H), 1.97 – 1.83 (m, 2H), 1.56 – 1.46 (m,
2H), 0.98 (t, J = 7.6 Hz, 3H). 13C NMR (100 MHz, Methanol-d4) δ
152.36, 151.79, 148.96, 146.50, 145.39, 145.16, 134.53, 134.50,
127.80, 126.87, 125.95, 124.50, 124.34, 110.92, 110.46, 103.49,
75.60, 59.05, 57.60, 33.29, 33.01, 29.55, 20.17, 14.26. LC-MS (ESI):
m/z calculated for C24H26NO4+ [M-Br-]+: 392.2, found: 392.3.
13-Bromo-10,11-dimethoxy-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']
benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide (18b)
Br2 (538.6 mg, 3.37 mmol) was added to compound 11b (298.5 mg,
0.67 mmol) in 10mL CH3COOH at room temperature. The resulting
mixture was then refluxed at 100 °C for 8 h. After the reaction was
completed as monitored by TLC and then cooled to room
temperature, the precipitates were filtered and washed with 10%
Na2S2O3 solution, then with H2O to afford the crude product 18b (200
mg) as a yellow solid which was used in the next step without further
purification. 18b: yield 58.6%, yellow soild; 1H NMR (400 MHz,
DMSO-d6) δ 10.13 (s, 1H), 8.58 (s, 1H), 8.23 (s, 1H), 7.43 (s, 1H),
7.10 (s, 1H), 6.17 (s, 2H), 5.08 (br s, 1H), 4.24 (br s, 1H), 4.15 – 4.11
(m, 6H), 2.76 (br s, 1H), 2.62 (br s, 1H), 2.46 – 2.35 (m, 1H), 2.30 (br
s, 1H).
10-(2-Bromoethoxy)-11-methoxy-6,7-dihydro-5H-[1,3]dioxolo
[4'',5'':4',5']benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide
(16b)
1,2-Dibromoethane (535.4 mg, 2.85 mmol) was added to compound
14b (191.2 mg, 0.57 mmol) in 10 mL CH3CN at room temperature.
The resulting mixture was refluxed at 85 °C for 3 h. After the reaction
was completed as monitored by TLC, then the mixture was
concentrated under reduced pressure. The residue was purified by
neutral Al2O3 column chromatography (dichloromethane /CH3OH =
100:1) to give compound 16b (64.1 mg) as a yellow solid. 16b: yield
21.5%, yellow solid, m.p. = 130 - 131 ℃; 1H NMR (400 MHz, DMSO-
d6) δ 10.02 (s, 1H), 8.55 (s, 1H), 8.26 (d, J = 9.2 Hz, 1H), 8.11 (d, J =
9.2 Hz, 1H), 7.31 (s, 1H), 7.09 (s, 1H), 6.16 (s, 2H), 5.01 (br s, 1H),
4.67 – 4.50 (m, 2H), 4.26 (br s, 1H), 4.13 (t, J = 5.2 Hz, 2H), 4.08 (s,
10,11-Dimethoxy-13-phenyl-6,7-dihydro-5H-[1,3]dioxolo[4'',5'':4',5']
benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide (19b)
15mL toluene, 5mL C2H5OH and 5mL H2O were added to a mixture
of Na2CO3 (84 mg, 0.79 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol),
phenylboronic acid (96.4 mg, 0.79 mmol) and compound 18b (200
mg, 0.39 mmol) under an inert atmosphere. The resulting mixture
was refluxed at 100 °C for 14 h. After the reaction was completed as
monitored by TLC, the mixture was then filtered, washed with EtOAc
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
FULL PAPER
(10 mL × 4). The filtrate was washed with brine, dried over
anhydrous Na2SO4 and concentrated under reduced pressure. The
residue was purified by silica gel column chromatography
(dichloromethane /CH3OH = 20:1) to afford compound 19b (40.4 mg)
as a yellow solid. 19b: yield 20.2%, yellow solid, m.p. = 77 – 78 ℃;
1H NMR (400 MHz, DMSO-d6) δ 10.18 (s, 1H), 8.13 (s, 1H), 7.97 (s,
1H), 7.69 (d, J = 7.2 Hz, 2H), 7.61 (t, J = 7.2 Hz, 2H), 7.54 (t, J = 7.2
Hz, 1H), 7.28 (s, 1H), 7.05 (s, 1H), 6.12 (d, J = 15.6 Hz, 1H), 5.12 (br
s, 1H), 4.23 (br s, 1H), 4.17 (s, 3H), 4.15 (s, 3H), 2.72 (br s, 1H),
2.64 (br s, 1H), 2.43 (br s, 1H), 2.27 (br s, 1H).13C NMR (100 MHz,
DMSO-d6) δ 150.31, 149.56, 146.79, 143.37, 136.55, 135.68, 133.29,
130.21, 130.16, 129.73, 129.08, 128.63, 126.70, 124.57, 122.76,
109.77, 109.47, 101.93, 62.10, 57.25, 57.10, 31.24, 27.81. LC-MS
(ESI): m/z calculated for C27H24NO4+ [M-Br-]+: 426.2, found: 426.2.
3.28 – 3.17 (m, 2H), 2.86 (dd, J = 15.2, 4.8 Hz, 1H), 2.67 – 2.53 (m,
1H), 2.04 (d, J = 15.2 Hz, 1H). 13C NMR (100 MHz, DMSO-d6) δ
150.66, 148.01, 145.87, 144.85, 135.35, 132.83, 130.37, 128.95,
127.73, 125.06, 124.10, 123.02, 120.43, 113.39, 111.94, 111.83,
101.67, 73.32, 61.34, 59.99, 59.38, 55.98, 54.81, 32.30, 28.70,
+
22.61. LC-MS (ESI): m/z calculated for C28H30NO4 [M-Br-]+: 444.2,
found: 444.1.
8-Benzyl-11,12-dimethoxy-6,7,8,9,14,14a-hexahydro-5H-[1,3]dioxolo
[4'',5'':4',5']benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide
(22b)
The compound 22b was prepared according to the procedure of
compound 21b. 22b: yield 79.8%, light yellow solid, m.p. = 168 –
169 ℃; 1H NMR (400 MHz, DMSO-d6) δ 7.68 – 7.59 (m, 2H), 7.58 –
7.49 (m, 3H), 7.19 (s, 1H), 7.00 (s, 1H), 6.86 (s, 1H), 6.77 (s, 1H),
6.08 (s, 2H), 5.46 (dd, J = 13.2, 4.8 Hz, 1H), 5.23 (d, J = 15.2 Hz,
1H), 4.76 (d, J = 13.2 Hz, 1H), 4.56 (d, J = 13.2 Hz, 1H), 3.84 (d, J =
15.2 Hz, 2H), 3.79 (d, J = 4.8 Hz, 1H), 3.74 (s, 3H), 3.68 (s, 3H),
3.41 (d, J = 15.2 Hz, 1H), 3.26 – 3.12 (m, 2H), 2.86 (dd, J = 15.2, 4.8
Hz, 1H), 2.65 – 2.53 (m, 1H), 2.06 (d, J = 15.2 Hz, 1H). 13C NMR
(100 MHz, DMSO-d6) δ 153.75, 153.14, 151.04, 140.47, 138.04,
135.41, 134.18, 132.80, 130.41, 127.44, 123.33, 117.15, 116.98,
116.34, 115.44, 106.83, 68.46, 66.47, 60.76, 60.71, 59.51, 37.60,
10,11-Dimethoxy-5,6,7,9,14,14a-hexahydro-[1,3]dioxolo[4'',5'':4',5']
benzo[1',2':3,4]azepino[1,2-b]isoquinoline (20b)
NaBH4 (74.1 mg, 1.96 mmol) was added to compound 11b (218.2
mg, 0.49 mmol) and K2CO3 (62 mg, 0.49 mmol) in CH3OH (10 mL)
portionwise at 0 ℃. The resulting mixture was refluxed at 65 ℃ for 3
h. After the reaction was completed as monitored by TLC, then the
mixture was concentrated and pour to H2O (10 mL), extracted with
DCM (15 mL×3). The organic layers were combined, washed with
brine, dried over anhydrous Na2SO4 and concentrated under
reduced pressure to give compound 20b (200 mg) as pale yellow oil
which was used in the next step without further purification.
+
34.56, 27.78. LC-MS (ESI): m/z calculated for C28H30NO4 [M-Br-]+:
444.2, found: 444.1.
Biological Evaluation
Enzymatic Inhibition Assays
11,12-Dimethoxy-5,6,7,9,14,14a-hexahydro-[1,3]dioxolo[4'',5'':4',5']
benzo[1',2':3,4]azepino[1,2-b]isoquinoline (20b’)
The p300 HAT inhibitory assays were performed using isotope-
labelled 3H-Ac-CoA and substrate peptide by Shanghai
ChemPartner Co., Ltd (http://www.chempartner.com/). The materials
include p300 (BPS, Cat. No. 50071), Ac-CoA (Sigma, Cat. No.
A2056), 3H-Ac-CoA (PerkinElmer, Cat. No. NET290), and C646
(Calbiochem, Cat. No. 382113) for positive control. The substrate
solution and stop solution were prepared by Shanghai ChemPartner.
The reaction is started by the addition of 10 μL substrate solution,
followed by 60 mins incubation at room temperature, then adding 10
μL stop solution to stop the reactions. Then, 25 μL reaction solutions
are transferred to the Flashplate, incubated for 1 hour, and washed
three times using dH2O and 0.1% Tween-20 prior to reading on
Microbeta. The inhibition rate is calculated using the formula: Inh%=
(Max-Signal)/(Max-Min)*100. By using Graphpad Prism 5, the IC50
values were calculated from dose-response curves obtained at 10
different concentrations for each compound.
The compound 20b’ was prepared according to the procedure of
compound 20b. Crude product 20b’ (218 mg, yellow oil) was used in
the next step without further purification.
8-Benzyl-10,11-dimethoxy-6,7,8,9,14,14a-hexahydro-5H-[1,3]dioxolo
[4'',5'':4',5']benzo[1',2':3,4]azepino[1,2-b]isoquinolin-8-ium bromide
(21b)
Benzyl bromide (484 mg, 2.83 mmol) was added to compound 20b
(200 mg) in 10 mL CH3CN at room temperature. The resulting
mixture was stirred at 50 ℃ for 3 h. After the reaction was completed
as monitored by TLC, then the mixture was concentrated under
reduced pressure. The residue was purified by silica gel column
chromatography (dichloromethane /CH3OH = 50:1) to give and to
give compound 21b (216.7 mg) as a light yellow solid. 21b: yield
84%, light yellow solid, m.p. = 180 – 182 ℃; 1H NMR (400 MHz,
DMSO-d6) δ 7.68 (dd, J = 7.2, 2.0 Hz, 2H), 7.58 – 7.51 (m, 3H), 7.20
(s, 1H), 7.11 (d, J = 8.8 Hz, 1H), 7.06 – 6.99 (m, 2H), 6.08 (s, 2H),
5.52 (dd, J = 13.2, 4.8Hz, 1H), 5.37 (d, J = 15.2 Hz, 1H), 4.91 (d, J =
13.2 Hz, 1H), 4.61 (d, J = 13.2 Hz, 1H), 3.95 – 3.84 (m, 2H), 3.79 (s,
3H), 3.67 (d, J = 13.2 Hz, 1H), 3.60 (s, 3H), 3.44 (d, J = 15.2 Hz, 1H),
Molecular Docking Simulations
The molecular docking simulations in this study were carried out
using AutoDock Vina.[21] The chemical structures of B-homo
palmatine and berberine derivatives were prepared as described
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10.1002/ejoc.201701693
European Journal of Organic Chemistry
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Keywords: total synthesis  palmatine  berberine  p300 hat 
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Entry for the Table of Contents (Please choose one layout)
Layout 2:
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Zhongzhen Yang, Yong Zhang, Xin
Chen, Weijian Li, Guo-Bo Li,* Yong Wu*
Page No. – Page No.
12a
Total Synthesis and Evaluation of
B-homo Palmatines
B-homo Berberines
p300 HAT IC50 = 0.42 μM
New
Berberine
B-homo
Palmatine
as
and
p300
Derivatives
New B-homo palmatine and berberine derivatives have been prepared, which
exhibited potent inhibition to p300 histone acetyltransferase.
Histone Acetyltransferase Inhibitors
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