Design and total synthesis of Mannich derivatives of marine natural product lamellarin D as cytotoxic agents

Article abstract of DOI:10.1016/j.ejmech.2014.08.038

Enlightened by the modification route from Camptothecin (CPT) to Topotecan and based on classical drug design theory, a series of Mannich derivatives of lamellarin D were designed and synthesized in 26-27 steps starting from vanillin and isovanilin. All synthesized compounds were then biologically evaluated for their in vitro anti-cancer activities and Topo I inhibitory activities. The results showed that most target compounds exhibited Topo I inhibitory activities in equivalent level with that of lamellarin D. Compound SL-9 exhibited better Topo I inhibitory activity than that of lamellarin D. Compounds SL-2, SL-3, SL-4, SL-5 and SL-11 exhibited better anti-proliferative activity against HT-29 cells than that of lamellarin D.

Full text of DOI:10.1016/j.ejmech.2014.08.038

European Journal of Medicinal Chemistry 85 (2014) 807e817
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Design and total synthesis of Mannich derivatives of marine natural
product lamellarin D as cytotoxic agents
,
, c
Li Shen a, Nan Xie b, Bo Yang b, Yongzhou Hu a *, Yongmin Zhang a
a ZJU-ENS Joint Laboratory of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
b Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
c
ꢀ
ꢀ
Institut Parisien de Chimie Moleculaire, CNRS UMR 8232, Universite Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Enlightened by the modification route from Camptothecin (CPT) to Topotecan and based on classical drug
design theory, a series of Mannich derivatives of lamellarin D were designed and synthesized in 26e27
steps starting from vanillin and isovanilin. All synthesized compounds were then biologically evaluated
for their in vitro anti-cancer activities and Topo I inhibitory activities. The results showed that most target
compounds exhibited Topo I inhibitory activities in equivalent level with that of lamellarin D. Compound
SL-9 exhibited better Topo I inhibitory activity than that of lamellarin D. Compounds SL-2, SL-3, SL-4, SL-
5 and SL-11 exhibited better anti-proliferative activity against HT-29 cells than that of lamellarin D.
© 2014 Elsevier Masson SAS. All rights reserved.
Received 31 August 2013
Received in revised form
9 August 2014
Accepted 11 August 2014
Available online 12 August 2014
Keywords:
Lamellarin D
Mannich
Derivative
Anti-cancer
Topo I
Structureeactivity relationships
1. Introduction
activity to HIV-1 inhibition [18]. The 21-OCH3 group is not essential
[5]. Lactone analogues with opened ring B show decrease of the
Lamellarin D (Fig. 1), one of the first isolated lamellarins from
marine prosobranch mollusk Lamellaria sp. [1] in 1985, is a potent
topoisomerase I (Topo I) inhibitor [2] that induces apoptosis
through mitochondria mediated pathway [3] and reverses multi-
drug resistance caused by P-glycoprotein-mediated drug efflux [4].
Lamellarin D is one of the most extensively studied members in
lamellarins because of its potent anti-proliferative activities [5e8].
Increasing efforts have been involved in studying the total syn-
thesis, mechanism and modification of lamellarins, leading to the
presence of several instructive reviews in the past years [6e11].
Lamellarin D incorporates a benzopyrano[40,30:4,5]pyrrolo[2,1-a]
isoquinolin-6-one scaffold.
SARs research of lamellarin D shows: 20-OH on ring A is
essential to maintain cytotoxicity [2,5,6] and participate in
hydrogen bond interactions with the side chains of Glu356 [14].
Incorporating amino acid residues [15], nuclear localization signal
peptide conjugates [16] or PEG conjugates [17] on 20-OH may in-
crease activity and solubility. Replacing the 20-OH group with a 20-
sulphate group, its biological function would change from cytotoxic
cytotoxicity [13]. The carbonyl group of the lactone is a bonding
side for Arg364 [14]. Replacement of the lactone ring with a lactam
[19] ring leads to partial retainment of cytotoxicity. Certain de-
rivatives with a 1-amine moiety rather than a 4-amine moiety
showed even more potent cytotoxicity than that of lamellarin D
[20]. The D
5,6 of ring D is an essential element for Topo I inhibition
and retaining anti-proliferative activity [2]. The 8-OH of ring E is
essential for cytotoxicity [5,6] and participates in hydrogen bond
interactions with the side chains of Asn722 [14]. The 14-OH and 13-
OCH3 groups of ring F are not essential to maintain the cytotoxicity
[5,6]. The amino derivative with a 3-aminoprop-1-en-2-yl group
rather than a ring F shows inhibition against Topo I but introduces
apoptosis through mitochondria mediated pathway [3]. Topo I in-
hibition and anti-proliferative activity for the analogues without F
ring [21] have not been reported. We now report a novel design and
total synthesis of Mannich derivatives of lamellarin D, which is
described in details in the following sections.
2. Mannich derivation design
Increasing the water-solubility of lamellarin derivatives has
* Corresponding author.
E-mail address: huyz@zju.edu.cn (Y. Hu).
been posed as a main challenge for structural modification and
http://dx.doi.org/10.1016/j.ejmech.2014.08.038
0223-5234/© 2014 Elsevier Masson SAS. All rights reserved.

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L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
methanesulfonation, acetation and a-bromination [25] to obtain 6.
Another part of isovanilin underwent hydroxyl protection, Henry
reaction [26e28] on aldehyde and reduction [22,28e31] to obtain
9. Secondly, the vanillin was treated with protection of hydroxyl
group, reduction, nucleophilic substitution [32] and hydrolysis [22]
to give 14. Then 14 and 9 were directly acylation [33] to yield 15,
which was transferred to isoquinoline 16 by BischlereNapieralski
reaction [22,33]. Condensation of isoquinoline 16 with phenacyl
bromide (6) under basic condition [22,25,34] gave the 1,2-
diphenyl-5,6-dihydropyrrolo[2,1-a]isoquinoline (17). Through
VilsmeiereHaack formylation [25], a formyl group was introduced
at C-3 position of 17 to provide 18. Then the formyl group of 18 was
oxidized [35] to carboxyl group to give 19. Hydrolysis of 19 with 17%
NaOH aqueous solution afforded the phenol derivative (20), which
was transformed into lactone (21) by intramolecular cyclization
reactions. Then reaction of 21 with DDQ [36,37] afforded the
lamellarin D with the 8, 14 and 20-OH groups selectively protected
(22). Finally, the target compounds SL-1~11 was obtained through
selective exposure of hydroxyl groups [5,38,39], Mannich reaction
[40] and deprotection of residual hydroxyl groups from 22 in turn.
Furthermore, lamellarin 501 could be obtained through depro-
tection of the benzyl, iso-propyl and mesyl groups of 21, similarly
lamellarin D could be obtained through the same method from 22.
As a result, eleven novel mono- and bis-Mannich derivatives of
lamellarin D SL-1~11 (Table 1) were synthesized in 26e27 steps
starting from vanillin and isovanilin. Lamellarin D and lamellarin
501 were synthesized and served as the reference compounds for
biological studies.
Fig. 1. Lamellarin D.
optimization. Incorporating amino acid residues [15], nuclear
localization signal peptide conjugates [16] or PEG conjugates [17]
on 8, 14, 20-OH of lamellarin D has been reported, however no
significant improvement in activity and solubility have been
observed yet. Enlightened by the modification route from the
typical Topo I inhibitor Camptothecin (CPT) to Topotecan and based
on classical drug design theory, a series of Mannich derivatives of
lamellarin D were designed by attaching different Mannich base
groups onto A-, E- or F-ring of lamellarin D together with the
application of several protection strategies on hydroxy groups at 8-,
14-, and 20-position of lamellarin D (Fig. 2).
3. Synthetic studies
Based on our previous work in synthesizing lamellarin
analogues [22], a modified N-ylide-mediate pyrrole formation
strategy was adopted, with isovanilin and vanilin as starting ma-
terials (Scheme 1). The retrosynthetic analysis on the basis of SL-1,
SL-6 and SL-7 as the model compounds showed that selectively
exposing the OH group of C-8, 14 or 20 position could successfully
introduce aminomethyl group on C-7, 15 or 19 position through
Mannich reaction. And the lamellarin D with selectively protected
hydroxyl groups could be built on lactone formation of N-ylide-
mediate pyrrole which condensed with isoquinoline and phenacyl
bromide. The phenacyl bromide could be prepared from isovanilin
through BaeyereVilliger oxidation, hydrolyzation and Friedele-
Crafts acylation, and then selectively protected hydroxyl groups
and bromination in turn. The isoquinoline could be prepared
through BischlereNapieralski reaction of ethanamide which
condensed with phenylacetic acid from isovanilin and phenyl-
ethanamine from vanillin. Furthermore, the strategy of phenol
protection should be considered at the beginning of the multistep
synthesis.
4. Biological studies and results discussion
The synthesized compounds (SL-1~11) were then measured for
their Topo I inhibitory activities by using a Topo I enzyme-reagent
kit (Takara, D2240A). And their anti-proliferation activities were
measured in vitro against four human cancer cell lines, including
colon carcinoma HT-29, breast carcinoma MDA-MB-231, leukaemia
K562 and liver hepatocellular carcinoma HepG2. Lamellarin 501
(SL-12) and lamellarin D (SL-13) were used as the negative control
and positive control respectively. The results are summarized in
Fig. 3 and Table 1.
As illustrated in Fig. 3, in the absence of Topo I (No Enzyme),
plasmid DNA mostly maintained the supercoiled status in the gel.
Meanwhile supercoiled DNA was entirely relaxed after adding
Topo I. As expected, lamellarin 501 (SL-12), the negative control,
didn't show significant inhibition against Topo I. In contrast, after
administrating lamellarin D (SL-13), the amount of supercoiled
DNA was significantly increased, which in line with previous
reports that lamellarin D inhibited the catalytic activity of Topo I.
These results were consistent with previous reports [2,6,41].
Nine Mannich derivatives SL-2, 3, 4, 5, 7, 8, 9, 10 and 11, rather
than SL-1 and 6, exhibited Topo I inhibitory activities (summa-
rized in Table 1) in comparison with the parent compound
lamellarin D. The Topo I inhibition of SL-9 was stronger than that
of lamellarin D.
The results of in vitro anti-proliferative activity evaluation
revealed that eleven Mannich derivatives of lamellarin D exhibited
moderate to potent anti-proliferative activities against tested four
human cancer cell lines. The anti-proliferative activities of SL-1~5
and SL-11 against HT-29 were even better than that of lamellarin D.
SL-1 and SL-5 showed better anti-proliferative activities than other
derivatives against all the four cancer cells.
The type and position of Mannich base groups on target com-
pounds could influence their biological activities. Generally
speaking, compounds (SL-1~6) with a Mannich base group at C-19
or C-7 position showed more potent anti-proliferative activities
As an important part of our research work on selective protec-
tion hydroxy groups of lamellarin D, protection strategies of phenol
groups on C-8, 14 and 20 positions were considered at the begin-
ning of the synthetic work according to the reagents and reaction
conditions. Based on the experience of trials, we found that MOM,
TMS and TBDMS were unstable under bromination and Henry re-
action, so that they did not meet our requirements in phenacyl
bromide or ethanamine part on R1, R3 and R4. The Ac and Ms were
unstable under base condition, so these two were not suitable to
choose on R2 of phenylacetic acid part. The PMB was not suitable to
choose on R1, R2 or R3, because it was easy to be deprotected on R1,
R2 or R3 at the presence of DDQ, which was the key reagent for the
oxidation of D
5,6. After repeated tests, we finally selected Ms for R1
protection, Bn for R2 protection, i-Pr for R3 protection and Ac for R4
protection.
On the basis of retrosynthetic analysis and selective protection
strategy, we took the synthetic route starting from vanillin and
isovanilin (Scheme 2).
Firstly, one part of isovanilin underwent BaeyereVilliger
oxidation,
hydrolysis,
FriedeleCrafts
acylation
[23,24],

L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
809
Fig. 2. Mannich derivation design on CPT (camptothecin) and lamellarin D (SL-1, SL-6 and SL-7 as the model compounds).
Scheme 1. Retrosynthetic analysis and strategy for the synthesis of the Mannich derivatives of lamellarin D, in which SL-1, SL-6 and SL-7 were chosen as the model compounds.
than that of compounds SL-7~9 with a Mannich base group at C-15
position. Compounds (SL-10 and SL-11) with two Mannich base
groups at C-19 and C-7 position could keep their Topo I inhibition
and anti-proliferative activities against HT-29, MDA-MB-231 and
K562 cells. Unexpectedly, SL-1 and SL-6 lost the ability to inhibit
Topo I, but their anti-proliferation activities were quite good. SL-9
maintain potent Topo I inhibitory activity, but its anti-proliferative
activity was not as good as its Topo I inhibition. There might be
other targets or mechanisms of the Mannich derivatives for the
anti-proliferative activity.
11 exhibited moderate Topo I inhibitory activities. Compounds SL-
2, 3, 4, 5 and 11 exhibited better anti-proliferation activity against
HT-29 cells than that of lamellarin D. Our study on lamellarin D-
based Mannich derivation may provide new insights for the
development of derivatives of lamellarin D as anti-cancer agents.
The study on other derivatization and further mechanism research
are still in progress.
6. Experimental materials and methods
6.1. Chemistry
5. Conclusions
Melting points were determined on a Büchi B-540 melting
apparatus and uncorrected. 1H NMR spectra and 13C NMR spectra
were recorded on Bruker AM-400 FT and Bruker AVIII500M spec-
Based on the retrosynthetic analysis, we synthesized eleven
novel lamellarin D Mannich derivatives were synthesized and
evaluated for their Topo I activity and anti-proliferative activity.
Most of the Mannich derivation of lamellarin D could keep the Topo
I inhibitory activity and partially enhance the anti-proliferation
activity against colon carcinoma HT-29, breast carcinoma MDA-
MB-231, leukaemia K562 and liver hepatocellular carcinoma
HepG2 cancer cell lines in vitro. Compounds SL-2, 3, 4, 5, 7, 8, 10 and
trometers. Chemical shifts values were expressed in
d ppm with
TMS as an internal standard. High resolution mass spectra, ESI
(positive) were recorded on an Agilent 6224 Accurate-Mass TOF LC/
MS spectrometer. Reactions were run in oven-dried glassware and
distilled solvents. Common reagents and intermediates were pu-
rified by established procedures [42].

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L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
Scheme 2. Reagents: (a) 30% H2O2, SeO2, DCM, 0 ꢀC; (b) 17% KOH a.q., MeOH, 20 ꢀC; (c) BF3ꢁEt2O, AcOH, 120 ꢀC; (d) MsCl, TEA, DCM, 0 ꢀC; (e) AcCl, TEA, DCM, 0 ꢀC; (f) BnNþEt3Br-3,
DCM, 0 ꢀC; (g) BnCl, K2CO3, DMF, 20 ꢀC; (h) MeNO2, NH4Ac, HOAc, ultrasonic; (i) LiAlH4, THF, 0e20 ꢀC; (j) i-PrBr, K2CO3, DMF, 20 ꢀC; (k) KBH4, MeOH, 20 ꢀC; (l) SOCl2, DCM, 0 ꢀC; (m)
NaCN, CH3CN, reflux; (n) KOH a.q., EtOH, reflux; (o) heat, 180 ꢀC; (p) POCl3, CH3CN, reflux; (q) NaHCO3, CH3CN, reflux; (r) POCl3, DMF, 0e20 ꢀC; (s) 2-methylbut-2-ene, NaClO2,
NaH2PO4, t-BuOH : THF : H2O (3:3:1), 0e20 ꢀC; (t) 17% KOH a.q., MeOH, 0e20 ꢀC; (u) DCC, DCM, 0 ꢀC; (v) DDQ, DCM, reflux; (w) TBAF, THF, 0e20 ꢀC; (x) Pd/C, H2(1 atm), EtOAc,
20 ꢀC; (y) 37% HCHO a.q., HOAc, secondary amine, 70 ꢀC; (z) TiCl4, DCM, 0e20 ꢀC.
6.1.1. 2-(2-Bromoacetyl)-4-methoxy-5-((methylsulfonyl)oxy)phenyl
acetate (6)
Ar-H), 4.39 (s, 2H, eCH2eBr), 3.95 (s, 3H, C-5-OCH3), 3.24 (s, 3H, C-
4-OMs), 2.38 (s, 3H, C-2-OAc).
This compound was prepared from appropriate acetophenone 5
according to literature procedures [25] in 70.6% yield. Mp 91e92 ꢀC.
6.1.1.1. 1-(2,4-Dihydroxy-5-methoxyphenyl)ethanone (3). This com-
pound was prepared from isovanillin according to literature
1H NMR (500 MHz, CDCl3)
d 7.47 (s, 1H, C-6-Ar-H), 7.24 (s, 1H, C-3-

L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
811
Table 1
The structures and anti-proliferative activities of lamellarin D Mannich derivatives.
No.
R1
R2
R3
Topo I inhibition
GI50
(
m
M)a
HT-29
MDA-MB-231
K562
HepG2
SL-1
SL-2
SL-3
H
H
H
H
H
H
ꢂ
þ
þ
5.46 1.47
2.52 0.51
2.92 0.70
3.30 0.37
5.78 0.51
9.75 0.71
0.43 0.03
1.04 0.28
2.37 0.43
2.63 0.99
5.04 2.98
6.83 2.69
SL-4
SL-5
SL-6
SL-7
SL-8
SL-9
SL-10
SL-11
H
H
H
H
H
þ
þ
ꢂ
þ
þ
þ
þ
þ
2.50 0.60
2.64 0.88
6.41 1.97
14.99 1.36
18.27 4.08
13.00 2.16
5.68 1.78
2.83 0.89
7.25 1.37
4.87 1.27
3.98 0.20
13.05 2.28
33.13 3.57
19.94 3.71
9.89 0.53
6.15 0.71
1.95 0.36
2.25 0.58
1.85 0.40
1.34 0.06
9.94 2.64
2.84 1.08
9.62 1.94
7.16 2.20
6.99 2.81
3.69 2.07
30.14 1.64
6.37 3.85
21.32 3.41
4.47 0.98
>50
H
H
H
H
H
H
H
H
H
15.81 2.62
SL-12
SL-13
(Lamellarin 501)
(Lamellarin D)
ꢂ (ꢂ [2])
þ (þ [2])
40.78 4.66
4.47 1.69 (5.10 [13])
17.89 1.84
0.32 0.06 (0.25 [13])
1.61 0.63
0.08 0.01
2.14 0.61
0.09 0.01 (0.02 [8])
a
Data was expressed as mean SEM from three independent experiments.
were dissolved in DCM (25 mL) at 0 ꢀC. MsCl (0.32 mL, 4.12 mmol)
in DCM (2 mL) was added dropwise over 30 min. The mixture was
stirred at 0 ꢀCe20 ꢀC for 2 h. Then the solvent was removed at
reduced pressure. The residue was taken up in DCM (50 mL),
washed with saturated aqueous NaHCO3 (50 mL), brine (50 mL) and
dried over Na2SO4. The solvent was removed in vacuo to get the
crude product, which was recrystallized from ether to obtain 1.03 g
pale white solid 4 in 96% yield. Mp 139e140 ꢀC. 1H NMR (500 MHz,
Fig. 3. Inhibition of Topo I-mediated relaxation of DNA by lamellarin 501, Lamellarin D
and its Mannich derivatives SL-1~11. Native supercoiled pBR322 DNA (0.5
incubated for 30 min at 37 ꢀC with 1 unit of calf thymus topoisomerase I in the absence
or presence of the compound at 100 M. Reactions were stopped with sodium dodecyl
ml) was
CDCl3) d 12.08 (s, 1H, C-2-Ar-OH), 7.25 (s, 1H, C-6-Ar-H), 6.97 (s, 1H,
m
C-3-Ar-H), 3.90 (s, 3H, C-5-OCH3), 3.24 (s, 3H, C-4-OMs), 2.63 (s, 3H,
eCH3). HR-MS (ESI, m/z): calcd for C10H12O6S [Mþ1]þ 261.0388,
found 261.0433.
sulphate. The DNA samples were run on an agarose gel followed by gel stain staining
and photographed under UV light. (Rel.: relaxed, Sc.: supercoiled).
6.1.1.3. 2-Acetyl-4-methoxy-5-((methylsulfonyl)oxy)phenyl acetate
(5). Acetophenone 4 (1.0 g, 3.8 mmol) and TEA (0.55 mL, 4.0 mmol)
were dissolved in DCM (25 mL) at 0 ꢀC. AcCl (0.28 mL, 4.0 mmol) in
DCM (2 mL) was added dropwise over 30 min. The mixture was
stirred at 0 ꢀCe20 ꢀC for 1.5 h. Then ice-water was added to quench
the reaction. The mixture washed with saturated aqueous NaHCO3
(50 mL), brine (50 mL) and dried over Na2SO4. The solvent was
removed in vacuo to get the crude product, which was recrystal-
lized from ether to obtain 1.16 g white solid 5 in 97% yield. Mp
procedures [24] in 3 steps with 62.4% yield as white solid. Mp
170.5e172.8 ꢀC (Lit. [12]: 171e172 ꢀC). 1H NMR (500 MHz, CDCl3)
d
12.58 (s, 1H, C-2-Ar-OH), 7.04 (s, 1H, C-6-Ar-H), 6.51 (s, 1H, C-3-Ar-
H), 6.28 (s, 1H, C-4-Ar-OH), 3.90 (s, 3H, C-5-OCH3), 2.55 (s, 3H,
eCH3).
6.1.1.2. 4-Acetyl-5-hydroxy-2-methoxyphenyl methanesulfonate (4).
Acetophenone 3 (0.75 g, 4.12 mmol) and TEA (0.57 mL, 4.12 mmol)

812
L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
103.4e105.8 ꢀC. 1H NMR (500 MHz, CDCl3)
7.36 (s, 1H, C-3-Ar-H), 3.96 (s, 3H, C-5-OCH3), 3.24 (s, 3H, C-4-OMs),
3.23 (s, 3H, eCH3), 2.67 (s, 3H, C-2-OAc).
d
7.38 (s, 1H, C-6-Ar-H),
6.1.6. 2-(8-Benzyloxy-1-(4-isopropoxy-3-methoxyphenyl)-9-
methoxy-5,6-dihydropyrrolo[2,1-a]isoquinolin-2-yl)-4-methoxy-5-
((methylsulfonyl)oxy)phenyl acetate (17)
Phenacyl bromides 6 (3.8 g, 10.0 mmol) and NaHCO3 (3.4 g,
40.0 mmol) was added in portion to
a solution of dihy-
6.1.2. 2-(3-Benzyloxy-4-methoxyphenyl)ethanamine (9)
droisoquinolin-2-ium chloride 16 (4.8 g, 10.0 mmol) in anhydrous
MeCN (100 mL) at room temperature. The mixture was stirred
under refluxing for 20 h. The solvent was removed in vacuo. The
residue was dissolved in EtOAc (100 mL), washed with brine
(50 mL) and dried over Na2SO4. The solvent was evaporated to give
a residue, which was purified by silica gel column chromatography
(PE:EtOAc ¼ 1:1) to afford 5.1 g of pure compound 17 as pale yellow
solid in 70% yield. Mp 95.4e96.7 ꢀC. 1H NMR (500 MHz, CDCl3)
This compound was prepared according to literature procedures
[31] from isovanillin in 3 steps with 60% yield as pale yellow oil. 1H
NMR (Lit. [31], 500 MHz, CDCl3)
d
7.43 (d, J ¼ 7.0 Hz, 1H, C-3-Ar-H),
7.35 (t, J ¼ 7.0 Hz, 1H, C-3-Ar-H), 7.29 (t, J ¼ 7.0 Hz, 1H, C-3-Ar-H),
6.83 (d, J ¼ 8.0 Hz, 1H, C-5-H), 6.7 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-6-H),
6.72 (d, J ¼ 2.0 Hz, 1H, C-5-H), 5.14 (s, 2H, C-3-O-CH2Ar) 3.89 (s, 3H,
C-4-OCH3), 2.86 (t, J ¼ 7.0 Hz, 2H, eCH2CH2NH2), 2.62 (t, J ¼ 7.0 Hz,
2H, eCH2CH2NH2), 1.78 (s, 2H, eCH2CH2NH2).
d
7.43 (d, J ¼ 7.0 Hz, 2H, C-7-Ar-H), 7.35 (t, 2H, J ¼ 7.0 Hz, C-7-Ar-H),
7.29 (t, J ¼ 7.0 Hz, 1H, C-7-Ar-H), 7.04 (s, 1H, C-2-Ar-H), 6.90 (s, 2H,
C-1-Ar-H, C-9-H), 6.80e6.82 (d, J ¼ 7.5 Hz, 3H, C-1-Ar-H, C-7,10-H),
6.73 (s, 1H, C-3-H), 6.53 (s, 1H, C-2-Ar-H), 5.13 (s, 2H, C-8-OCH2Ar),
4.47 (m,1H, C-1-Ar-OCH(CH3)2), 4.06 (t, 2H, C-5-CH2), 3.64 (s, 3H, C-
2-Ar-OCH3), 3.41 (s, 3H, C-1-Ar-OCH3), 3.40 (s, 3H, C-9-OCH3), 3.13
(s, 3H, C-2-Ar-OMs), 2.98 (t, 2H, C-6-CH2), 2.17 (s, 3H, C-2-Ar-OAc),
1.34 (d, J ¼ 6.0 Hz, 6H, C-1-Ar-OCH(CH3)2). HR-MS (ESI, m/z): calcd
for C40H41NO10S [MþNH4þ]þ 745.2789, found 745.2789.
6.1.3. 2-(4-Isopropoxy-3-methoxyphenyl)acetic acid (14)
This compound was prepared according to literature procedures
[22,43] from vanillin by etheration, reduction, chlorination, cyan-
ation and hydrolysation 5 steps of 53% yield as pale yellow solid 14.
Mp 72.4e73.1 ꢀC (Lit. [22]: 67e69 ꢀC). 1H NMR (Lit. [22], 400 MHz,
CDCl3)
d
8.80 (brs, 1H, eCH2COOH), 6.84 (d, 1H, J ¼ 8.4 Hz, C-5-Ar-
H), 6.81 (s, 1H, C-2-Ar-H), 6.79 (d, 1H, J ¼ 8.4 Hz, C-6-Ar-H), 4.49 (m,
1H, eCH(CH3)2), 3.86 (s, 3H, C-3-OCH3), 3.57 (s, 2H, eCH2COOH),
1.33(d, 6H, J ¼ 6.4 Hz, eOCH(CH3)2).
6.1.7. 2-(8-Benzyloxy-3-formyl-1-(4-isopropoxy-3-
methoxyphenyl)-9-methoxy-5,6-dihydropyrrolo[2,1-a]isoquinolin-
2-yl)-4-methoxy-5-((methylsulfonyl)oxy)phenyl acetate (18)
POCl3 (295 mg, 0.18 mL, 1.92 mmol) was added slowly to dry
DMF (1 mL) at 0 ꢀC and stirred for 0.5 h. Then a solution of 17
(900 mg, 1.24 mmol) in dry DMF (3 mL) was added dropwise. The
reaction mixture was warmed to 20 ꢀC and stirred for 6 h, then
quenched by ice-water, extracted with EtOAc, washed with satu-
rated aqueous NaHCO3 (20 mL), brine (20 mL) and dried over
Na2SO4. The solvent was removed in vacuo to get the crude product,
which was purified by column chromatography (PE:EtOAc ¼ 1:1) to
give 18 (710 mg, 76%) as yellow solid. Mp 181.0e181.8 ꢀC. 1H NMR
6.1.4. N-(3-benzyloxy-4-methoxyphenethyl)-2-(4-isopropoxy-3-
methoxyphenyl) acetamide (15)
Phenylacetic acid 14 (16.0 g, 71.3 mmol) and phenylethanamine
9 (19.8 g, 76.9 mmol) were stirred at 180 ꢀC for 2 h under nitrogen
atmosphere. The mixture was cooled down and dissolved in DCM
(150 mL), washed with 1 M HCl (100 mL), saturated aqueous
NaHCO3 (100 mL), brine (100 mL) and dried over Na2SO4. The sol-
vent was removed in vacuo to get the crude product, which was
purified by column chromatography (PE:EtOAc ¼ 1:1) to get a white
solid 15 in 67% yield. Mp 92.2e92.6 ꢀC. 1H NMR (500 MHz, CDCl3)
(500 MHz, CDCl3)
d
9.45 (s, 1H, C-3-CHO), 7.43 (d, J ¼ 7.0 Hz, 2H, C-
7-Ar-H), 7.37 (t, J ¼ 7.0 Hz, 2H, C-7-Ar-H), 7.31 (t, J ¼ 7.0 Hz, 1H, C-7-
Ar-H), 7.11 (s, 1H, C-2-Ar-H), 6.86 (t, J ¼ 6.9 Hz, 3H, C-1-Ar-H), 6.77
(s, 1H, C-9-H), 6.75 (s, 1H, C-7-H), 6.55 (s, 1H, C-2-Ar-H), 5.20 (s, 1H,
C-5-CH2), 5.16 (s, 2H, C-8-OCH2Ar), 4.49 (dt, J ¼ 12.0, 6.0 Hz, 1H, C-
1-Ar-OCH(CH3)2), 4.19 (s, 1H, C-6-CH2), 3.60 (s, 3H, C-2-Ar-OCH3),
3.49 (s, 3H, C-1-Ar-OCH3), 3.38 (s, 3H, C-9-OCH3), 3.16 (s, 3H, C-2-
Ar-OMs), 3.07(m, 1H, C-6-CH2), 2.89 (m, 1H, C-6-CH2), 2.07 (s, 3H,
C-2-Ar-OAc),1.33 (d, J ¼ 6.0 Hz, 6H, C-1-Ar-OCH(CH3)2). HR-MS (ESI,
m/z): calcd for C41H41NO11S [Mþ1]þ 756.2434, found 756.2474.
d
7.43 (d, J ¼ 7.5 Hz, 2H, N-3-Ar-30-Ar-H), 7.36 (t, J ¼ 7.5 Hz, 2H, N-3-
Ar-30-Ar-H), 7.29 (t, J ¼ 7.5 Hz, 1H, N-3-Ar-30-Ar-H), 6.81 (d,
J ¼ 8.0 Hz, 1H, N-3-Ar-50-H), 6.73 (d, J ¼ 8.0 Hz, 1H, C-2-Ar-50-H),
6.66 (s, 1H, C-2-Ar-20-H), 6.64 (s, 1H, N-3-Ar-20-H) 6.63 (d,
J ¼ 8.0 Hz, 1H, N-3-Ar-60-H), 6.52 (d, J ¼ 8.0 Hz, 1H, C-2-Ar-60-H),
5.39 (brs, 1H, eNH), 5.10 (s, 2H, N-3-Ar-30-OCH2Ar), 4.53e4.45 (m,
1H, C-2-Ar-40-OCH(CH3)2), 3.86 (s, 3H, C-2-Ar-30-OCH3), 3.78 (s, 3H,
N-3-Ar-40-OCH3), 3.44 (s, 2H, C-2-CH2), 3.37 (q, J ¼ 6.5 Hz, 2H, N-2-
CH2), 2.62 (t, J ¼ 6.5 Hz, 2H, N-3-CH2), 1.36 (d, J ¼ 6.0 Hz, 6H, C-2-Ar-
40-OCH(CH3)2). HR-MS (ESI, m/z): calcd for C28H33NO5 [Mþ1]þ
464.2392, found 464.2441.
6.1.8. 2-(2-Acetoxy-5-methoxy-4-((methylsulfonyl)oxy)phenyl)-8-
(benzyloxy)-1-(4-isopropoxy-3-methoxyphenyl)-9-methoxy-5,6-
dihydropyrrolo[2,1-a]isoquinoline-3-carboxylic acid (19)
To a solution of aldehyde 18 (1.25 g, 1.64 mmol) in THF (20 mL)
and t-BuOH (20 mL) was added 2-methylbut-2-ene (1.4 mL,
13.2 mmol) at 0 ꢀC. A solution of NaClO2 (447 mg, 4.94 mmol) and
NaH2PO4 (772 mg, 4.95 mmol) in 7 mL of water was added and the
mixture was stirred for 36 h at 20 ꢀC. The mixture was diluted with
saturated aqueous NH4Cl and extracted with EtOAc twice. The
combined organic extracts were washed with brine, dried over
Na2SO4, concentrated and purificated by column chromatography
(PE:EtOAc ¼ 1:1 to 1:20) to give 1.23 g of 19 (96%) as white solid. Mp
132.9e133.7 ꢀC. 1H NMR (500 MHz, CDCl3 filtered by dry K2CO3)
6.1.5. 6-Benzyloxy-1-(4-isopropoxy-3-methoxybenzyl)-7-methoxy-
3,4-dihydroisoquinolin-2-ium chloride (16)
POCl3 (4.64 g, 2.82 mL, 30.2 mmol) was added slowly to a so-
lution of ethanamide 15 (7.0 g, 15.1 mmol) in dry MeCN (15 mL) at
room temperature. The mixture was heated to reflux and stirred for
4 h, then cooled down and evaporated solvent in vacuo. The
remaining crude product was recrystallized from ether to give 5.1 g
of white solid in 70% yield. 1H NMR (500 MHz, CDCl3)
d 7.40 (7,
J ¼ 7.5 Hz, 1H, C-6-Ar-H), 7.35 (t, J ¼ 7.5 Hz, 2H, C-6-Ar-H), 7.29 (d,
J ¼ 7.5 Hz, 2H, C-6-Ar-H), 7.02 (s, 1H, C-8-H), 6.84 (d, J ¼ 8.5 Hz, 1H,
C-1-Ar-H), 6.81(d, J ¼ 8.5 Hz, 1H, C-1-Ar-H), 6.67(s, 1H, C-5-H), 5.15
(s, 2H, C-6-OCH2Ar), 4.43(m, 1H, C-1-Ar-OCH(CH3)2), 3.97 (s, 2H, C-
1-CH2), 3.78 (s, 3H, C-7-OCH3), 3.74 (s, 3H, C-1-Ar-OCH3), 3.69 (t,
2H, C-3-CH2), 2.58 (t, 2H, C-4-CH2), 1.32 (d, J ¼ 6.0 Hz, 6H, C-1-Ar-
OCH(CH3)2).
d
7.43 (d, J ¼ 7.0 Hz, 1H, C-7-Ar-H), 7.37 (t, J ¼ 7.0 Hz, 1H, C-7-Ar-H),
7.31 (t, J ¼ 7.0 Hz, 1H, C-7-Ar-H), 7.09 (s, 1H, C-2-Ar-H), 6.83 (d,
J ¼ 8.0 Hz, 1H, C-1-Ar-H), 6.78 (d, J ¼ 8.0 Hz, 1H, C-1-Ar-H), 6.76 (s,
1H, C-7-H), 6.68 (d, J ¼ 2.0 Hz, 1H, C-1-Ar-H), 6.55 (s, 1H, C-2-Ar-H),
5.15 (s, 2H, C-8-OCH2Ar), 4.95 (s, 1H, C-5-CH2), 4.50 (m, 1H, C-1-Ar-
OCH(CH3)2), 4.20 (s, 1H, C-5-CH2), 3.59 (s, 3H, C-2-Ar-OCH3), 3.51 (s,

L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
813
3H, C-1-Ar-OCH3), 3.36 (s, 3H, C-9-OCH3), 3.14 (s, 3H, C-2-Ar-OMs),
3.08 (m, 1H, C-6-CH2), 2.91 (m, 1H, C-6-CH2), 2.08 (s, 1H, C-2-Ar-
OAc), 1.32 (d, J ¼ 6.0 Hz, 3H, C-1-Ar-OCH(CH3)2). HR-MS (ESI, m/z):
calcd for C41H41NO12S [MþNHþ4 ]þ 789.2693, found 789.2697.
solvent was removed in vacuo and purified by silica gel column
chromatography (DCM:EtOAc ¼ 20:1) to give 23 (38 mg, 86%) as
white solid. Mp 230e231 ꢀC. 1H NMR (500 MHz, CDCl3)
d 9.22 (d,
J ¼ 7.3 Hz, 1H, C-8-H), 7.46 (d, J ¼ 7.5 Hz, 2H, C-11-O-Ar-H), 7.39 (t,
J ¼ 7.5 Hz, 2H, C-11-O-Ar-H), 7.32 (t, J ¼ 7.5 Hz, 1H, C-11-O-Ar-H),
7.20 (s, 1H, C-13-H), 7.18 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.17 (dd,
J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 7.13 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H),
7.11 (s,1H, C-10-H), 7.02 (s,1H, C-4-H), 6.98 (d, J ¼ 7.3 Hz,1H, C-9-H),
6.73 (s, 1H, C-1-H), 5.77 (s, 1H, C-3-OH), 5.26 (s, 2H, C-11-OCH2Ar),
4.66 (dt, J ¼ 12.0, 6.0 Hz, 1H, C-14-Ar-OCH(CH3)2), 3.85 (s, 3H, C-2-
OCH3), 3.51 (s, 3H, C-14-Ar-OCH3), 3.47 (s, 3H, C-12-OCH3), 1.44 (d,
J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2). HR-MS (ESI, m/z): calcd for
6.1.9. 11-Benzyloxy-14-(4-isopropoxy-3-methoxyphenyl)-2,12-
dimethoxy-6-oxo-8,9-dihydro-6H-chromeno[40,30:4,5]pyrrolo[2,1-
a]isoquinolin-3-yl methanesulfonate (21)
Acid 19 (100 mg, 0.13 mmol) was dissolved in MeOH (5 mL) at
0
ꢀC and 17% LiOH (0.5 mL) solution was added dropwise. The
mixture was stirred at 0 ꢀCe20 ꢀC for 1 h and concentrated. The
residue was dissolved in EtOAc (25 mL), washed with brine (10 mL)
and dried over Na2SO4. The solvent was evaporated to give a res-
idue, which was dissolved in dry DCM (10 mL). Then a solution of
DCC (53 mg, 0.26 mmol) in DCM was added dropwise into the re-
action mixture with ice-water bath and stirred at 0 ꢀCe20 ꢀC for 6 h.
The reaction mixture was concentrated and purified by silica gel
column chromatography (DCM:EtOAc ¼ 20:1) to give 53 mg of 21
(2 steps, 58%) as white solid. Mp 214.5e215.7 ꢀC. 1H NMR (500 MHz,
C
38H33NO8 [Mþ1]þ 632.2240, found 632.2276.
6.1.10.2. 11-Hydroxy-14-(4-isopropoxy-3-methoxyphenyl)-2,12-
dimethoxy-6-oxo-6H-chromeno[40,30:4,5]pyrrolo[2,1-a]isoquinolin-3-
yl methanesulfonate (26). Compound 22 (40.0 mg, 56.4 mmol) was
hydrogenated (1 atm H2) over 5% Pd-C (4.0 mg) in EtOAc (10 mL) at
25 ꢀC for 12 h. Then the reaction mixture was filtered, and the
filtrate was concentrated in vacuo. The residue was purified by
silica gel column chromatography (DCM:MeOH ¼ 20:1) to afford 28
as white solid (36 mg, 96%). Mp 249e250 ꢀC. 1H NMR (500 MHz,
CDCl3)
d
7.42 (d, J ¼ 7.0 Hz, 1H, C-11-O-Ar-H), 7.37 (t, J ¼ 7.0 Hz, 1H,
C-11-O-Ar-H), 7.33 (s, 1H, C-4-H), 7.30 (t, J ¼ 7.0 Hz, 1H, C-11-O-Ar-
H), 7.11 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-50-H), 7.06 (dd, J ¼ 8.0, 2.0 Hz, 1H,
C-14-Ar-60-H), 7.02 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-20-H), 6.81 (s, 1H, C-
13-H), 6.78 (s, 1H, C-10-H), 6.74 (s, 1H, C-1-H), 5.16 (s, 2H, C-11-
OCH2Ar), 4.79 (m, 1H, C-8-CH2), 4.73 (m, 1H, C-8-CH2), 4.57 (m,
1H, C-14-Ar-OCH(CH3)2), 3.84 (s, 3H, C-2-OCH3), 3.46 (s, 3H, C-14-
Ar-OCH3), 3.37 (s, 3H, C-12-OCH3), 3.19 (s, 3H, C-3-OMs), 3.06 (t,
J ¼ 8.0 Hz, 2H, C-9-CH2), 1.40 (t, J ¼ 6.0 Hz, 3H, C-14-Ar- OCH(CH3)2).
HR-MS (ESI, m/z): calcd for C39H37NO10S [Mþ1]þ 712.2172, found
712.2208.
CDCl3)
d
9.21 (d, J ¼ 7.4 Hz,1H, C-8-H), 7.38 (s,1H, C-4-H), 7.21 (s,1H,
C-10-H), 7.18 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz,
1H, C-14-Ar-H), 7.14 (s, 1H, C-13-H), 7.12 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-
H), 7.06 (d, J ¼ 7.4 Hz, 1H, C-9-H), 6.91 (s, 1H, C-1-H), 4.66 (dt,
J ¼ 12.0, 6.0 Hz, 1H, C-14-Ar-OCH(CH3)2), 3.86 (s, 3H, C-2-OCH3),
3.51 (s, 3H, C-12-OCH3), 3.48 (s, 3H, C-14-Ar-OCH3), 3.21 (s, 3H, C-3-
OMs),1.44 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2). HR-MS (ESI, m/z):
calcd for C32H29NO10S [Mþ1]þ 620.1546, found 620.1588.
6.1.10. 11-(Benzyloxy)-14-(4-isopropoxy-3-methoxyphenyl)-2,12-
dimethoxy-6-oxo-6H-chromeno[40,30:4,5]pyrrolo[2,1-a]isoquinolin-
3-yl methanesulfonate (22)
6.1.10.3. 11-(Benzyloxy)-4-((dimethylamino)methyl)-3-hydroxy-14-
(4-isopropoxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno
[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one (24-1). To a solution of 23
To a solution of 21 (80 mg, 0.13 mmol) in DCM (10 mL) was
added DDQ (45 mg, 0.20 mmol), stirred and refluxed for 12 h. Then
the reaction mixture was diluted by another portion of DCM
(10 mL), washed with saturated aqueous NaHCO3 (50 mL), brine
(20 mL) and dried over Na2SO4. The solvent was removed in vacuo
to get the crude product, which was purified by column chroma-
tography (DCM:EtOAc ¼ 20:1) to give 22 (74 mg, 80%) as white
(49.5 mg, 15.8
HCHO (9.3 mg, 25
25 L, 201
mol). The mixture was stirred at 70 ꢀC for 12 h and
m
mol) in HOAc (1 mL) was added a solution of 37%
m
L, 309 mol) and 33% aqueous Me2NH (8.3 mg,
m
m
m
concentrated. The residue was dissolved in EtOAc (50 mL), washed
with saturated aqueous NaHCO3 to pH ¼ 10, dried over Na2SO4. The
solvent was removed in vacuo and purified by silica gel column
chromatography (DCM:MeOH ¼ 20:1) to give 24 as brown solid
solid. Mp 236e237 ꢀC. 1H NMR (500 MHz, CDCl3)
d
9.22 (d,
(8.5 mg, 78%). 1H NMR (500 MHz, CDCl3)
d
9.15 (d, J ¼ 7.3 Hz, 1H, C-
J ¼ 7.4 Hz, 1H, C-8-H), 7.46 (d, J ¼ 7.3 Hz, 2H, C-11-O-Ar-H), 7.39 (s,
1H, C-4-H), 7.40 (t, J ¼ 7.3 Hz, 2H, C-11-O-Ar-H), 7.33 (t, J ¼ 7.3 Hz,
1H, C-11-O-Ar-H), 7.19 (d, J ¼ 8.0 Hz, 2H, C-14-Ar-50-H), 7.19 (s, 1H,
C-13-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-60-H), 7.13 (s, 1H, C-10-
H), 7.12 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-20-H), 7.04 (d, J ¼ 7.4 Hz, 1H, C-9-
H), 6.91 (s, 1H, C-1-H), 5.26 (s, 2H, C-11-OCH2Ar), 4.65 (m, 1H, C-14-
Ar-OCH(CH3)2), 3.86 (s, 3H, C-2-OCH3), 3.48 (s, 2H, C-14-Ar-OCH3),
3.47 (s, 3H, C-12-OCH3), 3.21 (s, 3H, C-3-OMs), 1.44 (d, J ¼ 6.0 Hz,
8-H), 7.45 (d, J ¼ 7.3 Hz, 2H), 7.38 (t, J ¼ 7.3 Hz, 2H), 7.33 (d,
J ¼ 7.3 Hz, 1H, C-11-O-Ar-H), 7.18 (s, 1H, C-13-H), 7.17 (d, J ¼ 8.0 Hz,
1H, C-14-Ar-H), 7.14 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 7.10 (d,
J ¼ 2.0 Hz,1H, C-14-Ar-H), 7.09 (s,1H, C-10-H), 6.97 (d, J ¼ 7.4 Hz,1H,
C-9-H), 6.75 (s, 1H, C-1-H), 5.25 (s, 2H, C-11-OCH2Ar), 4.67e4.60 (m,
1H, C-14-Ar-OCH(CH3)2), 4.34 (s, 2H, C-4-CH2N(CH3)2), 3.84 (s, 3H,
C-2-OCH3), 3.46 (s, 3H, C-14-Ar-OCH3), 3.46 (s, 3H, C-12-OCH3), 2.68
(s, 6H, C-4-CH2N(CH3)2), 1.43 (d,
OCH(CH3)2).
J
¼
6.0 Hz, 6H, C-14-Ar-
6H, C-14-Ar- OCH(CH3)2). 13C NMR (125 MHz, CDCl3)
d 154.75,
151.56, 149.84, 149.40, 147.83, 147.43, 145.40, 137.55, 136.20, 134.41,
128.72, 128.18, 127.80, 127.25, 124.58, 123.75, 123.00, 119.35, 117.42,
116.90, 114.81, 113.59, 113.16, 111.91, 109.57, 108.36, 106.89, 105.52,
71.84, 70.80, 56.26, 55.64, 55.19, 49.17, 38.62, 33.93, 25.61, 24.93,
21.91. HR-MS (ESI, m/z): calcd for C39H35NO10S [Mþ1]þ 710.2015,
found 710.2048.
6.1.10.4. 10-((Dimethylamino)methyl)-11-hydroxy-14-(4-isopropoxy-
3-methoxyphenyl)-2,12-dimethoxy-6-oxo-6H-chromeno[40,30:4,5]
pyrrolo[2,1-a]isoquinolin-3-yl methanesulfonate (27-1). To a solu-
tion of 26 (23.0 mg, 37
of 37% HCHO (9.3 mg, 25
(8.3 mg, 25 L, 201
mol). The mixture was stirred at 70 ꢀC for 12 h
mmol) in HOAc (2 mL) was added a solution
m
L, 309 mol) and 33% aqueous Me2NH
m
m
m
6.1.10.1. 11-(Benzyloxy)-3-hydroxy-14-(4-isopropoxy-3-
methoxyphenyl)-2,12-dimethoxy-6H-chromeno[40,30:4,5]pyrrolo[2,1-
and concentrated. The residue was dissolved in EtOAc (50 mL),
washed with saturated aqueous NaHCO3 to pH ¼ 10, dried over
Na2SO4. The solvent was removed in vacuo and purified by silica gel
column chromatography (DCM:MeOH ¼ 20:1) to afford 19-1 as
a]isoquinolin-6-one (23). To a solution of 22 (49.5 mg, 69.7
mmol) in
dry THF (25 mL), a solution of TBAF (20 mg, 76.7
mmol) in THF
(2 mL) was added in dropwise at 0 ꢀC. The mixture was stirred at
0 ꢀCe20 ꢀC for 12 h and concentrated. The residue was dissolved in
EtOAc (25 mL), washed with brine (10 mL), dried over Na2SO4. The
brown solid (18.0 mg, 78%). 1H NMR (500 MHz, CDCl3)
d 9.23 (d,
J ¼ 7.5 Hz, 1H, C-8-H), 7.38 (s, 1H, C-4-H), 7.23 (s, 1H, C-13-H), 7.20
(d, J ¼ 7.5 Hz, 1H, C-9-H), 7.18 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.16 (dd,

814
L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 7.11 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H),
6.89 (s, 1H, C-1-H), 4.67e4.62 (m, 1H, C-14-Ar-OCH(CH3)2), 4.16 (s,
2H, C-10-CH2N(CH3)2), 3.86 (s, 3H, C-2-OCH3), 3.48 (s, 3H, C-12-
OCH3), 3.45 (s, 3H, C-14-Ar-OCH3), 3.21 (s, 3H, C-3-OMs), 2.50 (s,
6H, C-10-CH2N(CH3)2), 1.44 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2).
HR-MS (ESI, m/z): calcd for C35H36N2O10S [Mþ1]þ 677.2124, found
677.2165.
(5.0 mg, 8.4
HCHO (1.85 mg, 5
L, 40 mmol). The mixture was stirred at 70 ꢀC for 12 h and
m
mol) in HOAc (1 mL) was added a solution of 37%
m
L, 62 mol) and 33% aqueous Me2NH (1.65 mg,
m
5
m
concentrated. The residue was dissolved in EtOAc (20 mL), washed
with saturated aqueous NaHCO3 to pH ¼ 10, dried over Na2SO4. The
solvent was removed in vacuo and purified by silica gel column
chromatography (DCM:MeOH ¼ 20:1) to provide 29 (4.1 mg, 75%)
as pale white solid. 1H NMR (500 MHz, CDCl3)
d
9.20 (d, J ¼ 7.7 Hz,
6.1.10.5. 14-(4-Isopropoxy-3-methoxyphenyl)-2,12-dimethoxy-6-
oxo-6H-chromeno[40,30:4,5]pyrrolo[2,1-a]isoquinoline-3,11-diyl
dimethanesulfonate (31). To a mixture of 23 (10.0 mg, 16 mmol) in
1H, C-8-H), 7.23 (s, 1H, C-13-H), 7.18 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H),
7.16 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.13 (d, J ¼ 7.7 Hz, 1H, C-9-H), 7.11
(s, 1H, C-14-Ar-H), 6.71 (s, 1H, C-1-H), 4.67e4.61 (m, 1H, C-14-Ar-
OCH(CH3)2), 4.21 (s, 2H, C-10-CH2N(CH3)2), 4.12 (s, 2H, C-4-
CH2N(CH3)2), 3.84 (s, 3H, C-2-OCH3), 3.46 (s, 3H, C-12-OCH3), 3.45
(s, 3H, C-14-Ar-OCH3), 2.52 (s, 6H, C-10-CH2N(CH3)2), 2.47 (s, 6H, C-
4-CH2N(CH3)2), 1.43 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2).
DCM (2.0 mL) and 0.1 M TEA (0.5 mL) in DCM was added dropwise
over 30 min at 0 ꢀC 0.1 M MsCl (0.3 mL) in DCM. The reaction
mixture was stirred at 0 ꢀCe20 ꢀC for 1 h. Then the solvent was
removed under reduced pressure. The residue was taken up in DCM
(20 mL), washed with saturated aqueous NaHCO3 (10 mL), brine
(10 mL) and dried over Na2SO4. The solvent was removed in vacuo
to get the crude product, which was purified by silica gel column
chromatography (DCM:EtOAc ¼ 30:1) to provide 11.0 mg of 31
6.1.10.9. 14-(4-Hydroxy-3-methoxyphenyl)-2,12-dimethoxy-6-oxo-
6H-chromeno[40,30:4,5]pyrrolo[2,1-a]isoquinoline-3,11-diyl dimetha-
nesulfonate (32). To a solution of 31 (11.0 mg, 16.0 mmol) in dry
(99%) as yellow solid. 1H NMR (500 MHz, CDCl3)
d
9.23 (d, J ¼ 7.4 Hz,
DCM (2 mL) was added dropwise a solution of 0.01 M TiCl4 in DCM
(0.5 mL) at 0 ꢀC. The mixture was gradually warmed to 20 ꢀC and
stirred for 12 h. The mixture was extracted with EtOAc (50 mL),
washed with saturated aqueous NaHCO3 (30 mL), brine (20 mL) and
dried over Na2SO4. The solvent was removed in vacuo to get the
crude product, which was purified by column chromatography
(DCM:EtOAc ¼ 10:1) to give 32 (8.0 mg, 76%) as pale white solid. 1H
1H, C-8-H), 7.66 (s, 1H, C-10-H), 7.38 (s, 1H, C-4-H), 7.31 (s, 1H, C-13-
H), 7.20 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-50-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H,
C-14-Ar-60-H), 7.13 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-20-H), 7.09 (d,
J ¼ 7.4 Hz, 1H, C-9-H), 6.88 (s, 1H, C-1-H), 4.69e4.63 (m, 1H, C-14-
Ar-OCH(CH3)2), 3.88 (s, 3H, C-2-OCH3), 3.48 (s, 3H, C-12-OCH3),
3.48 (s, 3H, C-14-Ar-OCH3), 3.23 (s, 3H, C-11-OMs), 3.21 (s, 3H, C-3-
OMs), 1.45 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2).
NMR (500 MHz, CDCl3)
d
9.22 (d, J ¼ 7.5 Hz, 1H, C-8-H), 7.37 (s, 1H,
C-4-H), 7.29 (s, 1H, C-13-H), 7.23 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-50-H),
7.17 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-60-H), 7.08 (d, J ¼ 7.5 Hz, 2H, C-
14-Ar-20-H, C-9-H), 6.87 (s, 1H, C-1-H), 5.89 (s, 1H, C-14-Ar-40-OH),
3.93 (s, 3H, C-2-OCH3), 3.50 (s, 3H, C-12-OCH3), 3.49 (s, 3H, C-14-Ar-
OCH3), 3.24 (s, 3H, C-11-OMs), 3.22 (s, 3H, C-3-OMs).
6.1.10.6. 4-((Dimethylamino)methyl)-3,11-dihydroxy-14-(4-
isopropoxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno
[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one (25-1). Compound 24-1
(8.5 mg, 12 mmol) was hydrogenated (1 atm H2) over 5% Pd-C (2 mg)
in EtOAc (80 mL) at 25 ꢀC for 12 h. Then the reaction mixture was
filtered, and the filtrate was concentrated in vacuo. The residue was
purified by silica gel column chromatography (DCM:MeOH ¼ 10:1)
to give 5.0 mg of 25-1 (68%) as pale white solid. 1H NMR (500 MHz,
6.1.10.10. 4-((Dimethylamino)methyl)-3,11-dihydroxy-14-(4-
hydroxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno[40,30:4,5]
pyrrolo[2,1-a]isoquinolin-6-one (SL-1). To
a solution of 25-1
CDCl3)
d
9.14 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.16 (d, J ¼ 8.0 Hz, 1H, C-14-
(5.0 mg, 8.4 mol) in dry DCM (5 mL) was added dropwise a so-
m
Ar-H), 7.15 (s, 1H, C-10-H), 7.14 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H),
7.12 (s, 1H, C-13-H), 7.10 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H), 6.98 (d,
J ¼ 7.4 Hz, 1H, C-9-H), 6.69 (s, 1H, C-1-H), 4.63 (dt, J ¼ 12.0, 6.0 Hz,
1H, C-14-Ar-OCH(CH3)2), 4.16 (s, 2H, C-4-CH2N(CH3)2), 3.83 (s, 3H,
C-2-OCH3), 3.47 (s, 3H, C-12-OCH3), 3.44 (s, 3H, C-14-Ar-OCH3), 2.47
(s, 6H, C-4-CH2N(CH3)2) 1.42 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2).
lution of 0.01 M TiCl4 in DCM (3.4 mL) at 0 ꢀC. The mixture was
gradually warmed to 20 ꢀC and stirred for 12 h. The mixture was
extracted with EtOAc (50 mL), washed with saturated aqueous
NaHCO3 (30 mL), brine (20 mL) and dried over Na2SO4. The solvent
was removed in vacuo to give the crude product, which was puri-
fied by column chromatography (DCM:EtOAc ¼ 10:1) to provide SL-
1 (3.4 mg, 73%) as pale white solid. 1H NMR (500 MHz, CDCl3)
d 9.19
6.1.10.7. 10-((Dimethylamino)methyl)-3,11-dihydroxy-14-(4-
isopropoxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno
[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one (28-1). To a solution of 27-
(d, J ¼ 7.0 Hz, 1H, C-8-H), 7.20 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.19 (s,
1H, C-10-H), 7.15 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.12 (s, 1H, C-13-H),
7.06 (s, 1H, C-14-Ar-H), 7.01 (d, J ¼ 7.0 Hz, 1H, C-9-H), 6.71 (s, 1H, C-
1-H), 4.21 (s, 2H, C-4-CH2N(CH3)2), 3.89 (s, 3H, C-2-OCH3), 3.52 (s,
3H, C-12-OCH3), 3.48 (s, 3H, C-14-Ar-OCH3), 2.51 (s, 6H, C-4-
CH2N(CH3)2). HR-MS (ESI, m/z): calcd for C31H28N2O8 [Mþ1]þ
557.1879, found 557.1927.
1 (6.0 mg, 8.9
solution of TBAF (20.0 mg, 76.7
m
mol) in dry THF (5 mL) was added dropwise at 0 ꢀC a
mmol) in THF (1 mL). The mixture
was stirred at 0 ꢀCe20 ꢀC for 12 h and concentrated. The residue
was dissolved in EtOAc (25 mL), washed with brine (10 mL), dried
over Na2SO4. The solvent was removed in vacuo and purified by
silica gel column chromatography (DCM:EtOAc ¼ 20:1) to give 30-1
(4.0 mg, 80%) as pale white solid. 1H NMR (500 MHz, CDCl3)
d
9.22
6.1.10.11. 4-((Diethylamino)methyl)-3,11-dihydroxy-14-(4-hydroxy-
3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno[40,30:4,5]pyrrolo
[2,1-a]isoquinolin-6-one (SL-2). The title compound was synthe-
sized from 23 by the similar procedure as that for SL-1. 1H NMR
(d, J ¼ 7.7 Hz, 1H, C-8-H), 7.25 (s, 1H, C-4-H), 7.23 (d, 1H, J ¼ 7.7 Hz,
1H, C-9-H), 7.18 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.15 (dd, J ¼ 8.0,
2.0 Hz, 1H, C-14-Ar-H), 7.13 (s, 1H, C-13-H), 7.11 (d, J ¼ 2.0 Hz, 1H, C-
14-Ar-H), 6.70 (s, 1H, C-1-H), 4.67e4.60 (m, 1H, C-14-Ar-
OCH(CH3)2), 4.23 (s, 2H, C-10-CH2N(CH3)2), 3.84 (s, 3H, C-2-OCH3),
3.49 (s, 3H, C-12-OCH3), 3.45 (s, 3H, C-14-Ar-OCH3), 2.54 (s, 6H, C-
10-CH2N(CH3)2), 1.44 (d, J ¼ 6.0 Hz, 6H, C-14-Ar-OCH(CH3)2).
(500 MHz, CDCl3)
d
9.19 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.20 (d, J ¼ 8.0 Hz,
1H, C-14-Ar-H), 7.19 (s, 1H, C-10-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-
14-Ar-H), 7.12 (s, 1H, C-13-H), 7.07 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H),
7.00 (d, J ¼ 7.4 Hz, 1H, C-9-H), 6.69 (s, 1H, C-1-H), 4.27 (s, 2H, C-4-
CH2N), 3.89 (s, 3H, C-2-OCH3), 3.52 (s, 3H, C-12-OCH3), 3.47 (s, 3H,
C-14-Ar-OCH3), 2.79 (q, J ¼ 7.0 Hz, 4H, C-4- CH2N(CH2CH3)2), 1.22 (t,
J ¼ 7.0 Hz, 6H, C-4-CH2N(CH2CH3)2). HR-MS (ESI, m/z): calcd for
6.1.10.8. 10-((Dimethylamino)methyl)-3,11-dihydroxy-14-(4-
isopropoxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno
[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one (29). To a solution of 28-1
C
33H32N2O8 [Mþ1]þ 585.2192, found 585.2228.

L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
815
6.1.10.12. 4-((Dipropylamino)methyl)-3,11-dihydroxy-14-(4-
hydroxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno[40,30:4,5]
pyrrolo[2,1-a]isoquinolin-6-one (SL-3). The title compound was
synthesized from 23 by the similar procedure as that for SL-1. 1H
6.1.10.16. 10-((Dimethylamino)methyl)-3,11-dihydroxy-14-(4-
hydroxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno[40,30:4,5]
pyrrolo[2,1-a]isoquinolin-6-one (SL-7). To
a solution of 28-1
(3.0 mg, 5.0 mol) in dry DCM (5 mL) was added dropwise a so-
m
NMR (500 MHz, CDCl3)
d
9.20 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.21 (d,
lution of 0.01 M TiCl4 in DCM (1.0 mL) at 0 ꢀC. The mixture was
gradually warmed to 20 ꢀC and stirred for 12 h. The mixture was
extracted with EtOAc (50 mL), washed with saturated aqueous
NaHCO3 (30 mL), brine (20 mL) and dried over Na2SO4. The solvent
was removed in vacuo to give the crude product, which was puri-
fied by column chromatography (DCM:EtOAc ¼ 10:1) to provide SL-
J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.20 (s, 1H, C-10-H), 7.17 (dd, J ¼ 8.0,
2.0 Hz, 1H, C-14-Ar-H), 7.13 (s, 1H, C-13-H), 7.08 (d, J ¼ 2.0 Hz, 1H, C-
14-Ar-H), 7.01 (d, J ¼ 7.4 Hz, 1H, C-9-H), 4.28 (s, 2H, C-4-CH2N), 3.90
(s, 3H, C-2-OCH3), 3.53 (s, 3H, C-12-OCH3), 3.48 (s, 3H, C-14-Ar-
OCH3), 2.65 (m, 4H, C-4-CH2N(CH2CH2CH3)2), 1.68 (m, 4H, C-4-
CH2N(CH2CH2CH3)2), 0.92 (t,
J
¼
7.2 Hz, 6H, C-4-
7 (1.9 mg, 70%) as pale white solid. 1H NMR (500 MHz, MeOD)
d 9.15
CH2N(CH2CH2CH3)2). HR-MS (ESI, m/z): calcd for C35H36N2O8
(brs, 1H, C-8-H), 7.44 (brs, 1H, C-9-H), 7.42 (s, 1H, C-4-H), 7.19 (d,
J ¼ 2.0 Hz, 1H, C-14-Ar-H), 7.13 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.04
(dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 6.78 (s, 1H, C-13-H), 6.75 (s, 1H,
C-1-H), 4.78 (s, 2H, C-10-CH2N(CH3)2), 3.89 (s, 3H, C-2-OCH3), 3.53
(s, 3H, C-12-OCH3), 3.50 (s, 3H, C-14-Ar-OCH3), 2.98 (s, 6H, C-10-
CH2N(CH3)2). HR-MS (ESI, m/z): calcd for C31H28N2O8 [Mþ1]þ
557.1879, found 557.1926.
[Mþ1]þ 613.2505, found 613.2553.
6.1.10.13. 3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-
dimethoxy-4-(piperidin-1-ylmethyl)-6H-chromeno[40,30:4,5]pyrrolo
[2,1-a]isoquinolin-6-one (SL-4). The title compound was synthe-
sized from 23 by the similar procedure as that for SL-1. 1H NMR
(500 MHz, CDCl3)
d
9.19 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.20 (d, J ¼ 8.0 Hz,
1H, C-14-Ar-H), 7.19 (s, 1H, C-10-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-
14-Ar-H), 7.13 (s, 1H, C-13-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H),
7.00 (d, J ¼ 7.4 Hz, 1H, C-9-H), 6.69 (s, 1H, C-1-H), 4.18 (s, 2H, C-4-
CH2N), 3.89 (s, 3H, C-2-OCH3), 3.52 (s, 3H, C-12-OCH3), 3.48 (s,
3H, C-14-Ar-OCH3), 2.71 (m, 4H, piperidin-H), 1.70 (m, 4H, piper-
idin-H), 1.54 (m, 2H, piperidin-H). HR-MS (ESI, m/z): calcd for
6.1.10.17. 3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-
dimethoxy-10-(piperidin-1-ylmethyl)-6H-chromeno[40,30:4,5]pyrrolo
[2,1-a]isoquinolin-6-one (SL-8). The title compound was synthe-
sized from 26 by the similar procedure as that for SL-7. 1H NMR
(500 MHz, CDCl3)
d
9.21 (d, J ¼ 7.6 Hz, 1H, C-8-H), 7.20 (d, J ¼ 8.0 Hz,
1H, C-14-Ar-H), 7.19 (s, 1H, C-4-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-
Ar-H), 7.11 (d, J ¼ 7.6 Hz, 1H, C-9-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-
H), 7.01 (s, 1H, C-13-H), 6.68 (s, 1H, C-1-H), 4.14 (s, 2H, C-10-CH2N),
3.89 (s, 3H, C-2-OCH3), 3.52 (s, 3H, C-12-OCH3), 3.46 (s, 3H, C-14-Ar-
OCH3), 2.67 (m, 4H, piperidin-H), 1.71 (m, 4H, piperidin-H), 1.54 (m,
2H, piperidin-H). HR-MS (ESI, m/z): calcd for C34H32N2O8 [Mþ1]þ
597.2192, found 597.2242.
C
34H32N2O8 [Mþ1]þ 597.2192, found 597.2243.
6.1.10.14. 3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-
dimethoxy-4-(morpholinomethyl)-6H-chromeno[40,30:4,5]pyrrolo
[2,1-a]isoquinolin-6-one (SL-5). The title compound was synthe-
sized from 23 by the similar procedure as that for SL-1. 1H NMR
(500 MHz, CDCl3)
d
9.19 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.21 (d, J ¼ 8.0 Hz,
1H, C-14-Ar-H), 7.19 (s, 1H, C-10-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-
14-Ar-H), 7.12 (s, 1H, C-13-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H),
7.02 (d, J ¼ 7.4 Hz, 1H, C-9-H), 6.71 (s, 1H, C-1-H), 4.23 (s, 2H, C-4-
CH2N), 3.89 (s, 3H, C-2-OCH3), 3.81 (m, 4H, morpholin-H), 3.52 (s,
3H, C-12-OCH3), 3.48 (s, 3H, C-14-Ar-OCH3), 2.76 (m, 4H, morpho-
lin-H). HR-MS (ESI, m/z): calcd for C33H30N2O9 [Mþ1]þ 599.1985,
found 599.2037.
6.1.10.18. 3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-
dimethoxy-10-(morpholinomethyl)-6H-chromeno[40,30:4,5]pyrrolo
[2,1-a]isoquinolin-6-one (SL-9). The title compound was synthe-
sized from 26 by the similar procedure as that for SL-7. 1H NMR
(500 MHz, CDCl3)
d
9.23 (d, J ¼ 7.7 Hz, 1H, C-8-H), 7.22 (s, 1H, C-13-
H), 7.20 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H), 7.16 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-
14-Ar-H), 7.13 (d, J ¼ 7.7 Hz, 1H, C-9-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-
Ar-H), 7.02 (s, 1H, C-4-H), 6.68 (s, 1H, C-1-H), 4.15 (s, 2H, C-10-
CH2N), 3.89 (s, 3H, C-2-OCH3), 3.80 (m, 4H, morpholin-H), 3.51 (s,
3H, C-12-OCH3), 3.46 (s, 3H, C-14-Ar-OCH3), 2.71 (m, 4H, morpho-
lin-H). HR-MS (ESI, m/z): calcd for C33H30N2O9 [Mþ1]þ 599.1985,
found 599.2030.
6.1.10.15. 14-(3-((Dimethylamino)methyl)-4-hydroxy-5-
methoxyphenyl)-3,11-dihydroxy-2,12-dimethoxy-6H-chromeno
[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one (SL-6). To a solution of 32
(4.0 mg, 6.1
HCHO (1.0 mg, 3
L, 30
mol). The mixture was stirred at 70 ꢀC for 12 h and
m
mol) in HOAc (2 mL) was added a solution of 37%
m
L, 33 mol) and 33% aqueous Me2NH (1.3 mg,
m
4
m
m
6.1.10.19. 4,10-Bis((dimethylamino)methyl)-3,11-dihydroxy-14-(4-
hydroxy-3-methoxyphenyl)-2,12-dimethoxy-6H-chromeno[4s0,30:4,5]
pyrrolo[2,1-a]isoquinolin-6-one (SL-10). To a solution of 29 (4.1 mg,
concentrated. The residue was dissolved in EtOAc (20 mL), washed
with saturated aqueous NaHCO3 to pH ¼ 10, dried over Na2SO4. The
solvent was removed in vacuo and purified by silica gel column
chromatography (DCM:MeOH ¼ 20:1) to give a brown solid, which
was dissolved in dry THF (5 mL). A solution of TBAF (5.0 mg,
6.3 mmol) in dry DCM (2 mL) was added dropwise a solution of
0.01 M TiCl4 in DCM (1.5 mL) at 0 ꢀC. The mixture was gradually
warmed to 20 ꢀC and stirred for 12 h. The mixture was extracted
with EtOAc (50 mL), washed with saturated aqueous NaHCO3
(30 mL), brine (20 mL) and dried over Na2SO4. The solvent was
removed in vacuo to give the crude product, which was purified by
column chromatography (DCM:EtOAc ¼ 10:1) to provide SL-10
19 m
mol) in THF (1 mL) was added dropwise at 0 ꢀC. The mixture
was stirred at 0 ꢀCe20 ꢀC for 12 h and concentrated. The residue
was dissolved in EtOAc (25 mL), washed with brine (10 mL), dried
over Na2SO4. The solvent was removed in vacuo and purified by
silica gel column chromatography (DCM:EtOAc ¼ 20:1) to give
1.5 mg of SL-6 as pale white solid (2 steps, 45%). 1H NMR (500 MHz,
(2.5 mg, 65%). as pale white solid. 1H NMR (500 MHz, CDCl3)
d 9.20
(d, J ¼ 7.7 Hz, 1H, C-8-H), 7.20 (s, 1H, C-13-H), 7.20 (d, J ¼ 8.0 Hz, 1H,
C-14-Ar-H), 7.15 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 7.11 (d,
J ¼ 7.7 Hz, 1H, C-9-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H), 6.67 (s, 1H,
C-1-H), 4.14 (s, 2H, C-10-CH2N(CH3)2), 4.08 (s, 2H, C-4-CH2N(CH3)2),
3.88 (s, 3H, C-2-OCH3), 3.47 (s, 3H, C-12-OCH3), 3.46 (s, 3H, C-14-Ar-
OCH3), 2.44 (s, 6H, C-10- CH2N(CH3)2), 2.43 (s, 6H, C-4-CH2N(CH3)2).
HR-MS (ESI, m/z): calcd for C34H35N3O8 [Mþ1]þ 614.2458, found
614.2504.
CDCl3)
d
9.23 (d, J ¼ 7.4 Hz, 1H, C-8-H), 7.47 (s, 1H, C-14-Ar-20-H),
7.23 (s, 1H, C-13-H), 7.21 (s, 1H, C-14-Ar-60-H), 7.04 (s, 1H, C-10-H),
7.02 (d, J ¼ 7.4 Hz, 2H, C-4, 9-H), 6.60 (s, 1H, C-1-H), 3.91 (s, 3H, C-2-
OCH3), 3.67 (s, 2H, C-14-Ar-30-CH2N(CH3)2), 3.50 (s, 6H, C-14-Ar-50-
OCH3, C-12-OCH3), 2.37e2.31 (m, 6H, C-14-Ar-30-CH2N(CH3)2). HR-
MS (ESI, m/z): calcd for C31H28N2O8 [Mþ1]þ 557.1879, found
557.4447.

816
L. Shen et al. / European Journal of Medicinal Chemistry 85 (2014) 807e817
6.1.10.20. 10-((Dimethylamino)methyl)-4-((dipropylamino)methyl)-
3,11-dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-dimethoxy-
(ID: D2240A) and pBR322 DNA (ID: D3050) were purchased from
TaKaRa (Dalian, China P.R.). DNA gel stain (ID: S33102) was pur-
chased from Yuyang corporation (Hangzhou, China).
6H-chromeno[40,30:4,5]pyrrolo[2,1-a]isoquinolin-6-one
(SL-11).
The title compound was synthesized from 30 (synthesized from 28-
1 by the similar procedure as that for 29) by the similar procedure
6.2.2. Cell viability analysis
as that for SL-10. 1H NMR (500 MHz, CDCl3)
d
9.20 (d, J ¼ 7.7 Hz, 1H,
The human cancer cell lines (HT-29, MDA-MB-231, K562 and
HepG2) were obtained from ATCC. To investigate the cell growth
inhibition activity of the compounds, 4000 cells were seeded into
each well from a 96-well plate. After 12 h incubation, the culture
medium was replaced with fresh medium containing graded con-
centrations of the test compound. After 72 h incubation, MTT assay
was performed to determine the cell viability. After the treatment,
C-8-H), 7.21 (s, 1H, C-13-H), 7.20 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-H),
7.17e7.14 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-H), 7.13 (d, J ¼ 7.7 Hz, 1H,
C-9-H), 7.06 (d, J ¼ 2.0 Hz, 1H, C-14-Ar-H), 6.67 (s, 1H, C-1-H), 4.26
(s, 2H, C-10-CH2N(CH3)2), 4.14 (s, 2H, C-4-CH2N(CH2CH2CH3)2), 3.89
(s, 3H, C-2-OCH3), 3.47 (s, 3H, C-12-OCH3), 3.46 (s, 3H, C-14-Ar-
OCH3), 2.67e2.62 (m, 4H, C-4-CH2N(CH2CH2CH3)2), 2.49 (s, 6H, C-
10-CH2N(CH3)2), 1.71e1.64 (m, 4H, C-4-CH2N(CH2CH2CH3)2), 0.91
(t, J ¼ 7.4 Hz, 6H, C-4-CH2N(CH2CH2CH3)2). HR-MS (ESI, m/z): calcd
for C38H43N3O8 [Mþ1]þ 670.3084, found 670.3125.
10
incubation, the medium was removed and formazan crystals were
dissolved with 150 l of DMSO for 10 min on a shaker. The absor-
ml of MTT solution (5 mg/mL) was added to each well. After 3 h
m
bance of each well was measured by a Multiskan GO UV/Vis
microplate spectrophotometer (Thermo Fisher Scientific, Waltham,
MA, USA) at a wavelength of 540 nm. The concentration induced
50% cell growth inhibition (GI50) was calculated from the dose-
dependent curve. This study was repeated for three times, and
6.1.10.21. 3,11-Dihydroxy-14-(4-hydroxy-3-methoxyphenyl)-2,12-
dimethoxy-8,9-dihydro-6H-chromeno[40,30:4,5]pyrrolo[2,1-a]iso-
quinolin-6-one (lamellarin 501, SL-12). To a solution of 21 (15.0 mg,
21.1
of TBAF (20.0 mg, 76.7
m
mol) in dry THF (5 mL) was added dropwise at 0 ꢀC a solution
mmol) in THF (1 mL). The mixture was stirred
data were expressed as mean
experiments.
SEM of three independent
at 0 ꢀCe20 ꢀC for 12 h and concentrated. The residue was dissolved
in EtOAc (25 mL), washed with brine (10 mL), dried over Na2SO4.
The solvent was removed in vacuo and purified by silica gel column
chromatography (DCM:EtOAc ¼ 20:1) to give a pale white solid,
which was dissolved in dry DCM (2 mL). A solution of 0.01 M TiCl4
in DCM (5 mL) was added dropwise at 0 ꢀC. The mixture was
gradually warmed to 20 ꢀC and stirred for 12 h. The mixture was
extracted with EtOAc (50 mL), washed with saturated aqueous
NaHCO3 (30 mL), brine (20 mL) and dried over Na2SO4. The solvent
was removed in vacuo to provide the crude product, which was
purified by column chromatography (DCM:EtOAc ¼ 10:1) to afford
6.5 mg of SL-12 (2 steps, 61%) as white solid. 1H NMR (Lit.
Acknowledgements
The authors are grateful to Ms Jianyang Pan for recording the
NMR spectra, Mr. Xiaoqing Lv and Mr. Peng Peng for recording the
HRMS data. Special thanks go to Dr. Xiaoming Zhu for supervising
the cytotoxicity assays, Mr. Ji Cao for the Topo I inhibition assays.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2014.08.038. These data include MOL
files and InChiKeys of the most important compounds described in
this article.
[15,44,45], 500 MHz, CDCl3)
d
7.13 (d, J ¼ 8.0 Hz, 1H, C-14-Ar-50-H),
7.08 (dd, J ¼ 8.0, 2.0 Hz, 1H, C-14-Ar-60-H), 6.97 (d, J ¼ 2.0 Hz, 1H, C-
14-Ar-60-H), 6.96 (s, 1H, C-4-H), 6.81 (s, 1H, C-10-H), 6.67 (s, 1H, C-
10-H), 6.63 (s, 1H, C-1-H), 5.75 (s, 1H, Ar-OH), 5.70 (s, 1H, Ar-OH),
5.63 (s, 1H, Ar-OH), 4.96e4.89 (m, 1H, C-8-CH2), 4.65e4.58 (m, 1H,
C-8-CH2), 3.87 (s, 3H, C-2-OCH3), 3.50 (s, 3H, C-12-OCH3), 3.41 (s,
3H, C-14-Ar-40-OCH3), 3.10e3.05 (m, 2H, C-9-CH2); HR-MS (ESI, m/
z): calcd for C28H23NO8 [Mþ1]þ 502.1457, found 502.1499.
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