Structural Modification of the 3,4,5-Trimethoxyphenyl Moiety in the Tubulin Inhibitor VERU-111 Leads to Improved Antiproliferative Activities

Article abstract of DOI:10.1021/acs.jmedchem.8b00827

Colchicine binding site inhibitors (CBSIs) hold great potential in developing new generations of antimitotic drugs. Unlike existing tubulin inhibitors such as paclitaxel, they are generally much less susceptible to resistance caused by the overexpression

Full text of DOI:10.1021/acs.jmedchem.8b00827

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Article
Structural modification of the 3,4,5-trimethoxyphenyl moiety in the
tubulin inhibitor VERU-111 leads to improved antiproliferative activities
Qinghui Wang, Kinsie Arnst, Yuxi Wang, Gyanendra Kumar, Dejian Ma, Hao
Chen, Zhongzhi Wu, Jinliang Yang, Stephen W. White, Duane D Miller, and Wei Li
J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.8b00827 • Publication Date (Web): 20 Aug 2018
Downloaded from http://pubs.acs.org on August 20, 2018
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Structural modification of the 3,4,5ꢀ
trimethoxyphenyl moiety in the tubulin inhibitor
VERUꢀ111 leads to improved antiproliferative
activities
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†
,ф,Π
†, Π
‡, Π
§
†
Qinghui Wang
, Kinsie E. Arnst , Yuxi Wang , Gyanendra Kumar , Dejian Ma , Hao
†
†
‡
§
†
†,
Chen , Zhongzhi Wu , Jinliang Yang , Stephen W. White , Duane D. Miller , Wei Li ⊥,*
†
Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health
‡
Science Center, Memphis, TN 38163, United States. State Key Laboratory of Biotherapy and
Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center of
§
Biotherapy, Chengdu, Sichuan 610041, China. Department of Structural Biology, St. Jude
Children’s Research Hospital, Memphis, TN 38105, United States. ⊥ Affiliated Cancer Hospital
&
Institute of Guangzhou Medical University, Guangzhou, Guangdong, 511436, China.
*Corresponding author: wli@uthsc.edu
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ABSTRACT: Colchicine binding site inhibitors (CBSIs) hold great potential in developing new
generations of antimitotic drugs. Unlike existing tubulin inhibitors such as paclitaxel, they are
generally much less susceptible to resistance caused by the overexpression of drug efflux pumps.
The 3,4,5ꢀtrimethoxyphenyl (TMP) moiety is a critical component present in many CBSIs,
playing an important role in maintaining suitable molecular conformations of CBSIs and
contributing to their high binding affinities to tubulin. Previously reported modifications to the
TMP moiety in a variety of scaffolds of CBSIs have usually resulted in reduced antiproliferative
potency. We previously reported a potent CBSI, VERUꢀ111 that also contains the TMP moiety.
Herein, we report the discovery of a VERUꢀ111 analogue 13f that is significantly more potent
than VERUꢀ111. The Xꢀray crystal structure of 13f in complex with tubulin confirmed its direct
binding to the colchicine site. In addition, 13f exhibited a strong tumor growth inhibitory effect
in vivo.
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INTRODUCTION
Microtubuleꢀtargeting agents (MTAs) such as paclitaxel interrupt the cell cycle and result in
mitotic arrest at the metaphase/anaphase transition, and eventually induce apoptosis of cancer
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ꢀ2
cells . Although MTAs have achieved great success in cancer treatment, their clinical efficacy
3
is often limited by the development of drugꢀresistance . Therefore, MTAs that can overcome
multidrug resistance (MDR) are highly desirable for the treatment of resistant phenotypes.
Currently, all FDA approved tubulin inhibitors for cancer treatment bind to either the paclitaxel
site or the vinca alkaloids site. Colchicine binding site inhibitors (CBSIs) destabilize
microtubules and have shown significant ability to overcome clinically relevant MDR
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ꢀ6
mechanisms . A number of CBSIs also effectively circumvent drug resistance resulting from
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the overexpression of the βꢀIII tubulin isoform in cancer cells . Therefore, CBSIs hold great
potential as a new generation of tubulin inhibitors.
The 3,4,5ꢀtrimethoxyphenyl (TMP) is a common moiety shared by many CBSIs, as shown in
Figure 1. This TMP moiety is crucial for maintaining suitable molecular conformations that are
8
needed for optimal interactions with tubulin , and for producing the maximum antiproliferative
activities. Attempts to modify this TMP moiety usually lead to significantly reduced anticancer
4
, 9ꢀ11
potency
. For example, substituting the methoxy with a bulky group or demethylating the
12ꢀ13
methoxy on the TMP moiety of colchicine were reported to reduce the potency
. In addition,
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removing or adding methoxy to TMP significantly impaired the antimitotic activity (>10ꢀfold) .
However, some isosteric modifications of the TMP in colchicine or Combretastatin A4 (CAꢀ4)
have been shown to maintain the potency to that of parent natural products colchicine or CAꢀ4.
For instance, Semenov et al have shown that isosteric replacement the TMP of CAꢀ4 with
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[
1,3]dioxole or [1,4]dioxane did not significantly reduced antimitotic activity when compared to
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CAꢀ4 . Cornigerine, a [1,3]dioxole analogue of colchicine, displayed equipotent antimitotic
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activity to that of the parent compound .
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We have previously reported the discovery of a 2ꢀarylꢀ4ꢀbenzoylꢀimidazole (ABI) scaffold as a
16
new class of CBSI . Subsequent structural optimization of the benzoyl moiety, the aryl moiety,
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and the imidazole fragment in this scaffold resulted in analogues with improved potency
.
VERUꢀ111 (Figure 1) is the best analogue from that series of structural optimizations. It has an
average IC value of 5.2 nM against a panel of cancer cell lines, is not a substrate of Pꢀ
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glycoprotein (Pꢀgp), and effectively inhibits tumor growth in paclitaxelꢀresistant models .
However, consistent with the structureꢀactivity relationships for many CBSIs, our previous
attempts to modify the TMP moiety in the ABI scaffold have all led to significantly reduced
activity.
6
Based on our recently reported high resolution crystal structure of DJ101 (Figure 1) , a close
analogue of VERUꢀ111, we discovered that: (1) only one methoxy of the TMP moiety in DJ101
was involved in the formation of a hydrogen bond interaction with the βꢀCys241 residue of
tubulin; and (2) there is very limited space around the TMP moiety to accommodate any larger
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moieties . We hypothesized that two of the three methoxys of the TMP moiety could be
optimized to improve antiproliferative activity without damaging the interactions to tubulin. To
test this hypothesis, we carried out a focused SAR investigation of VERUꢀ111 by modifying the
TMP moiety, specifically by linking two adjacent methoxy moieties into a conformationally
restricted ring system. Among the eight VERUꢀ111 analogues synthesized, 13f contains a unique
3
ꢀ methoxybenzo[4,5]ꢀdioxene moiety and exhibits the greatest improvement of antiproliferative
activity against a panel of melanoma cell lines, with IC values ranging from 1.1 to 3.3 nM
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compared with VERUꢀ111 (5.6 to 8.1 nM). We solved the crystal structure of 13f in complex
with tubulin to confirm its direct binding to the colchicine site and to understand the structural
basis of its potency.
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CHEMISTRY
Scheme 1 shows the synthetic method we followed to access the commercially expensive or
unavailable benzoyl chlorides. In brief, commercially available methyl 3ꢀmethoxyꢀ4,5ꢀ
dihydroxybenzoate was treated with dibromomethane or 1,3ꢀdibromopropane to form 1a and 1b
in the presence of potassium carbonate. The cyclized benzoates were then hydrolyzed under
basic condition to provide carboxylic acids 2a and 2b. 2a and 2b were subsequently refluxed
with thionyl chloride in DCM to generate benzoyl chlorides 3a and 3b, which were used directly
for next step without purification.
Another commercially unavailable benzoyl chloride 8 was prepared following Scheme 2.
Methyl 3ꢀmethoxyꢀ4,5ꢀdihydroxybenzoate was refluxed together with allyl bromide in the
presence of potassium carbonate to generate alkylated methyl benzoate 4. An isomerization/ring
21
closing metathesis strategy as reported in the literature was followed to furnish the dioxene
moiety in 6. In brief, 4 was treated with a catalytic equivalent of (Ph P) Ru(CO)(Cl)H in toluene
3
3
to provide 5, which was subjected to Grubbs` reaction to afford 6. Hydrolysis of the methyl ester
under basic condition provided 7, which was converted to benzoyl chloride 8 by refluxing with
thionyl chloride.
ABI structure was constructed through a Suzuki coupling/Grignard reaction strategy as
depicted in Scheme 3. In short, 2ꢀ(Trimethylsilyl)ethoxymethyl (SEM)ꢀprotected compound 9
was obtained from the treatment of 2,4,5ꢀtribromoimidazole with SEMCl in the presence of
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sodium hydride. 9 coupled with 1ꢀ(Phenylsulfonyl)ꢀ3ꢀindolylboronic acid pinacol ester in the
presence of Pd (dba) and 2ꢀdicyclohexylphosphinoꢀ2′,4′,6′ꢀtriisopropylbiphenyl to provide 10 in
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34% yield. It is worth mentioning that Suzuki coupling reaction of this tribromo substrate under
current condition was not regioselective. Coupling reactions happening on the 4ꢀ or 5ꢀbromo
were also observed. 10 was treated with iꢀPrMgCl(LiCl) and benzoyl chlorides to furnish
compounds 11aꢀ11f in 31ꢀ48% yields. Bromo on the imidazole moiety and benzenesulfonyl
were simultaneously removed in the presence of Pd(OAc) , PPh , and K CO in nꢀBuOH under
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reflux condition, giving 12aꢀ12f in 76ꢀ89% yields. Deprotection of SEM using TFA in
dichloromethane finally provided VERUꢀ111 analogues 13aꢀ13f in 79ꢀ92% yields.
In a parallel SAR investigation focusing on modification of the indole moiety of VERUꢀ111
(manuscript in preparation), we demonstrate that replacing the 3ꢀindolyl with either a 4ꢀindolyl
or a 4ꢀmethylꢀ3ꢀindolyl moiety greatly improve the antiproliferative activity. Thus, we herein
also produced analogues 19 and 25 to determine the combinational effect of the unique 3ꢀ
methoxybenzo[4,5]ꢀdioxene moiety with the 4ꢀindolyl moiety or 4ꢀmethylꢀ3ꢀindolyl moiety.
Analogue 19 was synthesized according to Scheme 4. To access 19, the dibromo species 16 was
generated beforehand. In brief, commercially available 4ꢀbromoindole was treated with
benzenesulfonyl chloride in the presence of sodium hydride to provide 14 in 93% yield. 14 was
then subjected to Miyaura borylation, which was catalyzed by Pd(pddf) Cl .CH Cl to generate
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2
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5 in 86% yield. The boronic ester 15 was subsequently subjected to Suzuki coupling in the
presence of Pd (dba) and 2ꢀdicyclohexylphosphinoꢀ2′,4′,6′ꢀtriisopropylbiphenyl to produce
2
3
dibromo intermediate 16 in 31% yield. With 16 in hand, it was then treated with 8 in the
presence of iꢀPrMgCl(LiCl) to form 17, which was subjected to deprotection to eventually yield
analogue 19 in 67% yield over two steps. To synthesize analogue 25, we followed the synthetic
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method as shown in Scheme 5. The imidazole intermediate 21 was prepared by following a
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reported procedure , which involved imidazole formation (in the presence of ammonium
hydroxide and glyoxal) and bromination (in the presence of Nꢀbromosuccinimide). 21 was
subsequently treated with SEMCl and sodium hydride to afford intermediate 22 in 70% yield
over two steps. 22 was then subject to Grignard reaction in the presence of iꢀPrMgCl(LiCl) and 8
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to provide compound 23 in 37% yield. Treatment of 23 with Pd(OAc) , K CO , and PPh under
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reflux condition followed by TFA successfully afforded analogue 25 in 69% over two steps.
RESULTS AND DISCUSSION
rd
VERUꢀ111 is a clinical candidate initiated by VERU Healthcare to develop as 3 line
hormonal therapy, but it also exhibits potent antiproliferative activities against melanoma cell
lines and is currently being actively evaluated in many other cancer types both in vitro and in
vivo, such as prostate, pancreatic and breast cancer (unpublished data). To compare the activity
2
2
of VERUꢀ111 that was reported previously to those of our new analogues, their
antiproliferative effects were evaluated in 3 human melanoma cell lines (A375, M14, and
RPMI7951). Colchicine was used as a positive control (n=4). The in vitro cell viability following
7
2 h exposure to the analogues is shown in Table 1.
Benzo[4,5]ꢀdioxane analogue 13a lacks the 3ꢀmethoxy present in the TMP of VERUꢀ111. It
exhibited remarkable loss of cytotoxicity (IC ranges from 119 to 218 nM). Ring contraction of
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the sixꢀmember benzo[4,5]ꢀdioxane ring to the fiveꢀmember benzo[4,5]ꢀdioxole ring resulted in
analogue 13b, which showed comparable antiproliferative activity to that of 13a. In contrast to
1
3a, the 3ꢀmethoxybenzo[4,5]ꢀdioxane analogue 13c increased the antiproliferative potency and
had IC values ranging from 11.3 to 29.2 nM. This is consistent with our previous SAR, where
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we discovered that removing one or more of the methoxy groups in the TMP moiety negatively
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affects the antiproliferative potency for this scaffold . Similarly, introducing the 3ꢀmethoxy to
the benzo[4,5]ꢀdioxole analogue 13b led to the formation of 13d, which restored the potency
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(
IC ranges from 3.5 to 5.6 nM, 30ꢀfold more active than 13b). Interestingly, this fiveꢀ
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membered ring analogue was ~4ꢀfold more potent than the sixꢀmembered ring analogue 13c.
Thus, while the 3ꢀmethoxy was crucial for the activities of VERUꢀ111 analogues, the size of the
cyclic rings on the phenyl moiety also played an important role (13c vs 13d). Consistent with
this, further increasing the ring size to a sevenꢀmembered ring resulted in 3ꢀ
methoxybenzo[4,5]dioxepin analogue 13e, which had significantly decreased potency (IC50
ranging from 32.2 to 47.7 nM). By comparing 13c, 13d and 13e, it was revealed that the activity
for the size of this saturated ring is 5>6>7 (Table 1).
We next introduced an unsaturation to this ring by synthesizing 13f, a unique 3ꢀ
methoxybenzo[4,5]ꢀdioxene analogue. Interestingly, 13f (IC values ranging from 1.1 to 3.3
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nM) exhibited the most potent antiproliferative activity among the analogues solely modifying
the TMP moiety (13aꢀ13f, Table 1). To determine the combination modifications to both the
TMP and indole moieties on 13f, we further produced analogues 19 and 25. While the 4ꢀindolyl
analogue 19 exhibited ~ 11ꢀfold reduced antiproliferative activity when compared to 13f, the 4ꢀ
methylꢀ3ꢀindolyl analogue 25 (IC values ranging from 6.1 to 8.8 nM) was only slightly less
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potent than 13f. We also expanded our assessment of 13f into prostate cancer cell lines and
taxaneꢀresistant prostate cancer cell lines to determine the efficacy in another cell type, and the
result is shown in Figure S1. Other colchicine binding site inhibitors are reportedly less
susceptible to taxaneꢀrelated drug resistance and we therefore are keen to determine if 13f would
2
3ꢀ25
still be efficacious in taxaneꢀresistant models
. 13f was tested against paclitaxel in PCꢀ3,
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paclitaxelꢀresistant PCꢀ3/TxR, DU145, and docetaxelꢀresistant DU145/TxR prostate cancer cell
lines. Paclitaxel was more potent in the parental PCꢀ3 cell lines with an IC of 1.1 ± 0.2 nM
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compared to 15.2 ± 1.3 nM for 13f, which is not surprising given paclitaxel’s potency and
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clinical success. However, in resistant PCꢀ3/TxR cell lines, paclitaxel had a resistance index of
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03.5 and an IC of 113.9 ± 4.3 nM whereas 13f was more potent and demonstrated an IC of
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.6 ± 0.5 nM and a resistant index of 0.5. Although paclitaxel achieved significant potency in the
sensitive DU145 cell line (1.5 ± 0.2 nM), no effect was observed at all in the DU145/TxR cells at
concentrations up to 1µM. In contrast, 13f demonstrated IC s of 42.2 ± 3.6 and 81.5 ± 11.6 nM
5
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against DU145 and DU145TxR cells and had a resistant index of only 1.9. These data support
the development of this scaffold as an alternative treatment for cancers resistant to taxane
treatment. Overall, our SAR result show that the TMP moiety in VERUꢀ111 can be modified
without negatively impacting antiproliferative activities.
To confirm that 13f maintains its mechanism of action as a tubulin polymerization inhibitor,
we performed a tubulin polymerization assay (Figure 2). The vehicle control caused an
extensive increase in tubulin polymerization, giving a Vmax= 27. Colchicine, which was used as a
positive control, and 13f both inhibited tubulin polymerization with calculated Vmax values of 0.5
and 0, respectively. These results confirm that 13f maintains its mode of action by inhibiting
tubulin assembly and interfering with tubulin dynamics.
To understand the molecular basis of the strong interaction of 13f with tubulin, we determined
the crystal structure of the T2RꢀTTL (consisting of α/βꢀtubulin, the stathminꢀlike domain of RB3,
26ꢀ27
and tubulin tyrosine ligase)
in complex with 13f at a resolution of 2.85 Å (PDB ID: 6D88).
Details of the Xꢀray diffraction data collection and structure refinement statistics are provided in
Table 2. As expected, 13f occupies the colchicine binding site at the interface of the αꢀ and βꢀ
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tubulin, mostly confined in a deep pocket in βꢀtubulin opposite the GTP molecule that is bound
in a pocket in the αꢀtubulin (Figures 3A and S2). There are two α/βꢀtubulin heterodimers in this
complex and both interfaces are occupied by the small molecule. In both heterodimers (Chain
A/B and C/D), 13f forms virtually identical interactions. First, it forms three hydrogen bonds
with the surrounding amino acids: an imidazole NH to carbonyl of Thr179 (αꢀtubulin); an indole
NH to Ser178 (αꢀtubulin) and Asn347 (βꢀtubulin) via a water molecule; and a carbonyl linker to
Asp249 (βꢀtubulin) (Figure 3B). Second, the 3ꢀmethoxybenzo[4,5]ꢀdioxene moiety is stacked
between Cys239 and Leu253 from βꢀtubulin, the latter making a piꢀH interaction with the ring.
Finally, the imidazole ring is surrounded by Leu246 and Asn256 from βꢀtubulin while the indole
ring is surrounded by both Lys350 and Met257 from βꢀtubulin and Val181 from αꢀtubulin.
Colchicine targets the β subunit and keeps the tubulin from adopting a straight conformation,
thus inhibiting microtubule assembly, 13f also blocks the curvedꢀtoꢀstraight conformational
change of tubulin by steric clashes with surrounding secondary structure elements (Figure 3C),
and therefore shares the same mechanism of action as that of colchicine.
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Prior to the in vivo study, the in vitro metabolic stabilities of analogues 13a-13f were examined
by measuring their halfꢀlives upon incubation with mouse, rat and human liver microsomes in
the presence of an NADPH regeneration system. The results are summarized in Table 3. Overall,
1
3f showed the highest stability in rat liver microsomes and also exhibited satisfying stabilities
against mouse and human liver microsomes. Since it is also the most potent analogue, we
selected 13f for in vivo efficacy evaluation in an A375 melanoma xenograft model in nude mice.
After tumors were established, mice were randomized and treated every other day for 15 days by
i.p. injection with either 15 mg/kg 13f, 30 mg/kg 13f, 15 mg/kg paclitaxel, or a vehicle control
solution (Figure 4A). All drugꢀtreated groups caused a significant decrease in tumor growth
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based on both tumor volume and tumor weight (Figure 4B and C). The average tumor growth
inhibition (TGI) for the groups treated with 15 mg/kg and 30 mg/kg of 13f was 54.8% and
73.9%, respectively. These results were similar to the paclitaxelꢀtreated group, which was used
as a positive control and had an average TGI of 70.7%. The inhibitory action of 13f was also
demonstrated by the reduction in tumor weight, where the tumors of the 30 mg/kg group
weighed 65.0% less than the control group and the paclitaxel group averaged 62.3% less (Figure
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C). Mouse weights and activities were monitored to assess for apparent acute toxicities, and
significant deviations of animal weight were not observed (Figure 4D). Therefore, we conclude
that 13f is effective at inhibiting tumor growth in this xenograft model without causing apparent
toxicity at doses up to 30 mg/kg.
CONCLUSION
Modifying the TMP moiety of CBSIs is usually unsuccessful in improving antiproliferative
activities. Based on our recently discovered tubulin inhibitor VERUꢀ111 and the crystal structure
of its close analogue DJ101, we described the synthesis of eight new VERUꢀ111 analogues and
their SAR evaluation by focusing on the TMP modification. Our results showed that isosteric
(conformationally restricted) replacement of the TMP is feasible to significantly increase the
antiproliferative activities in this scaffold. We identified the analogue 13f, which contains a
unique 3ꢀmethoxybenzo[4,5]ꢀdioxene moiety, that demonstrated more potent antiproliferative
activity than VERUꢀ111 and achieved IC values ranging from 1.1ꢀ3.3 nM in melanoma cell
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0
lines. While this improvement in antiproliferative activity is not dramatic, these results clearly
demonstrated the feasibility of modifying this TMP moiety. In addition, compared to paclitaxel,
1
3f had a significantly improved resistance index in parental and taxaneꢀresistance prostate
cancer cell lines, suggesting its potential against drugꢀresistant phenotypes. Crystallographic
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analysis revealed that the interactions between 13f and tubulin is centered on a hydrogenꢀ
bonding network, which provides potential avenues for future modifications to improve potency.
13f maintained the same mechanism of action as its prototype VERUꢀ111 as an inhibitor of
tubulin polymerization. Moreover, 13f significantly inhibited tumor growth in vivo without
observable toxicity in a mouse melanoma xenograft model. Overall, our study provides a
successful example of modifying the TMP moiety of CBSIs in this scaffold to enhance
antiproliferative activity while not affecting the mechanistic and safety profile.
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EXPERIMENTAL SECTION
General chemistry. Tetrahydrofuran was distilled from sodiumꢀbenzophenone. All other
solvents and chemical reagents were obtained from commercial sources and directly used
without further purification. Glassware was ovenꢀdried before use. All reactions were performed
under an argon atmosphere. TLC was performed on silica gel 60 GF254 and monitored under
UV light or visualized using phosphomolybdic acid reagent. Flash chromatography was
performed on 230ꢀ400 mesh silica gel (Fisher Scientific). Melting points were recorded on a
MPA100 Automated Melting Point Apparatus. NMR spectra were obtained on a Bruker Ascend
4
00 (Billerica, MA) spectrometer or a Varian Inovaꢀ500 spectrometer (Agilent Technologies,
Santa Clara, CA). HRꢀMS were obtained on Waters Acquity UPLC linked to a Waters Acquity
Photodiode Array Detector and Waters qTof mass detector. All compounds reported herein with
biological data had purities ≥95% as determined by HPLC. The purity of associated compounds
was verified by the HPLC study performed on BEH C18 (2.1ꢁ×ꢁ50ꢁmm, 1.7ꢁꢂm) column using a
mixture of solvent acetonitrile/water (with 0.1% formic acid) at a flow rate of 0.3ꢁml/min and
monitoring by UV absorption at the appropriate wavelength. Chemical shifts are given in ppm
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with tetramethylsilane (TMS) as an internal reference. All coupling constants (J) are given in
Hertz (Hz).
General procedure A for the synthesis of alkylated methyl benzoate 1a, 1b and 4. To a
solution of the methyl 3ꢀmethoxyꢀ4,5ꢀdihydroxybenzoate in acetonitrile was added potassium
carbonate and appropriate bromide. The mixture was refluxed overnight and then cooled to room
temperature; the precipitate was filtered off and washed with dichloromethane. The combined
filtration was evaporated under vacuum to give the oily crude which was further purified with
flash chromatography on silica. Elution with hexane/ethyl acetate (5:1ꢀ2:1) gave 1a, 1b and 4.
1
1
1
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General procedure B for the synthesis of benzoic acids 2a, 2b and 7. To a solution of the
methyl benzoate 1a, 1b or 6 (1.0 mmol) in dioxane (5 ml) was added a solution of lithium
o
hydroxide (1.5 mmol) in water (3 ml). The mixture was stirred at 50 C until the TLC indicated
the completion of the reaction. The solvents were removed under reduced pressure and the
resulting residue was partitioned between water (10 ml) and DCM (10 ml), and the pH value was
adjusted to 5 using 1M HCl solution. The organic solvents were then combined, dried over
Na SO , filtered and evaporated under reduced pressure. The crude was purified with flash
2
4
chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:1) gave 2a, 2b and 7.
General procedure C for the synthesis of benzoyl chloride 3a, 3b and 8. To a solution of
the benzoic acid 2a, 2b or 7 (0.8 mmol) in DCM (5 ml) was added thionyl chloride (1.5 ml). The
o
mixture was stirred at 50 C for 3 h. The solvents were then removed under reduced pressure and
the corresponding crude benzoyl chloride was directly used for next step.
General procedure D for the synthesis of 11a-11f, 17 and 23. To a stirred solution of
compound 10 or 16 or 21 (1.0 mmol) in anhydrous THF (3.0 ml) under argon was added
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isopropylmagnesium chloride lithium chloride complex solution (1.3 M in THF, 0.92 ml, 1.2
mmol) at room temperature. The mixture was stirred for 1 h and was added benzoyl chlorides
(1.3 mmol) in anhydrous THF (1 ml). Reaction was kept stirring at room temperature for 1 h and
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then refluxed for 30 min. A saturated NH Cl solution was then added to quench the reaction. The
4
reaction mixture was extracted with ethyl acetate, washed with brine and dried with Na SO . The
2
4
combined extracts were evaporated under vacuum to give the crude product which was purified
with flash chromatography on silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 11a-
1
1f, 17 and 22.
General procedure E for the synthesis of 12a-12f, 18 and 24. To a suspension of 11a-11f or
17 or 23 (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine (26 mg,
.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The mixture
0
was heated to reflux for 4 h. nꢀBuOH was removed under reduced pressure. The residue was
partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were then
evaporated under reduced pressure. The crude was purified with flash chromatography on silica.
Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12a-12f, 18 and 24.
General procedure F for the synthesis of 13a-13f, 19 and 25. To a solution of 12a-12f or 18
or 24 in DCM (1 ml) was added trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and
the solvent was evaporated under reduced pressure. The residue was partitioned between
saturated NaHCO solution and EtOAc. The combined organic solvents were then evaporated
3
under reduced pressure. The crude was purified with flash chromatography on silica. Elution
with hexane/ethyl acetate (4:1ꢀ1:2) gave pure 13a-13f, 19 and 25.
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Methyl 7-methoxybenzo[d][1,3]dioxole-5-carboxylate (1a). Following general procedure A,
to a solution of the methyl 3ꢀmethoxyꢀ4,5ꢀdihydroxybenzoate (2.5 mmol) in acetonitrile (10 ml)
was added potassium carbonate (6.0 mmol) and dibromomethane (2.75 mmol). The mixture was
refluxed overnight and then cooled to room temperature; the precipitate was filtered off and
washed with dichloromethane. The combined filtration was evaporated under vacuum to give the
oily crude which was further purified with flash chromatography on silica. Elution with
1
1
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hexane/ethyl acetate (5:1ꢀ2:1) gave 1a as colorless oil in 42% yield. H NMR (400 MHz,
Chloroformꢀd) δ 7.32 (d, J = 1.4 Hz, 1H), 7.19 (d, J = 1.4 Hz, 1H), 6.04 (s, 2H), 3.93 (s, 3H),
+
3
.87 (s, 3H). HRMS: calculated for C H O [M+H] 211.0606, found 211.0607.
1
0
11
5
Methyl 9-methoxy-3,4-dihydro-2H-benzo[b][1,4]dioxepine-7-carboxylate (1b). Following
general procedure B, to a solution of the methyl 3ꢀmethoxyꢀ4,5ꢀdihydroxybenzoate (2.5 mmol)
in acetonitrile (10 ml) was added potassium carbonate (6.0 mmol) and 1,3ꢀdibromopropane (2.75
mmol). The mixture was refluxed overnight and then cooled to room temperature; the precipitate
was filtered off and washed with dichloromethane. The combined filtration was evaporated
under vacuum to give the oily crude which was further purified with flash chromatography on
1
silica. Elution with hexane/ethyl acetate (5:1ꢀ2:1) gave 1b as colorless oil in 36% yield. H NMR
(400 MHz, Chloroformꢀd) δ 7.31 (d, J = 2.0 Hz, 1H), 7.25 (d, J = 2.0 Hz, 1H), 4.39 – 4.22 (m,
6
H), 3.88 (s, 3H), 2.22 (q, J = 5.8 Hz, 2H), 1.35 (t, J = 7.1 Hz, 3H). HRMS: calculated for
+
C H O [M+H] 239.0919, found 239.0917.
12
15
5
7-methoxybenzo[d][1,3]dioxole-5-carboxylic acid (2a). Following general procedure B, to a
solution of the methyl benzoate 1a (1.0 mmol) in dioxane (5 ml) was added a solution of lithium
o
hydroxide (1.5 mmol) in water (3 ml). The mixture was stirred at 50 C until the TLC indicated
the completion of the reaction. The solvents were removed under reduced pressure and the
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resulted residue was partitioned between water (10 ml) and DCM (10 ml), pH value was adjusted
to 5 using 1M HCl solution. The organic solvents were then combined, dried over Na SO ,
2
4
filtered and evaporated under reduced pressure. The crude was purified with flash
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chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:1) gave 2a as colorless oil in
1
8
8% yield. H NMR (400 MHz, Acetoneꢀd ) δ 11.11 (s, 1H), 7.34 (d, J = 1.5 Hz, 1H), 7.15 (d, J
6
+
=
1.5 Hz, 1H), 6.10 (s, 2H), 3.93 (s, 3H). HRMS: calculated for C H O [M+H] 197.0450,
9
9
5
found 197.0451.
9
-methoxy-3,4-dihydro-2H-benzo[b][1,4]dioxepine-7-carboxylic acid (2b). Following
general procedure B, to a solution of the methyl benzoate 1b (1.0 mmol) in dioxane (5 ml) was
added a solution of lithium hydroxide (1.5 mmol) in water (3 ml). The mixture was stirred at 50
o
C until the TLC indicated the completion of the reaction. The solvents were removed under
reduced pressure and the resulted residue was partitioned between water (10 ml) and DCM (10
ml), pH value was adjusted to 5 using 1M HCl solution. The organic solvents were then
combined, dried over Na SO , filtered and evaporated under reduced pressure. The crude was
2
4
purified with flash chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:1) gave 2b
1
as colorless oil in 91% yield. H NMR (400 MHz, Chloroformꢀd) δ 10.87 (s, 1H), 7.39 (d, J = 2.0
Hz, 1H), 7.31 (d, J = 2.0 Hz, 1H), 4.41 (t, J = 5.8 Hz, 2H), 4.29 (t, J = 5.9 Hz, 2H), 3.90 (s, 3H),
+
2
.25 (p, J = 5.8 Hz, 2H). HRMS: calculated for C H O [M+H] 225.0763, found 225.0765.
1
1
13
5
Methyl 3,4-bis(allyloxy)-5-methoxybenzoate (4). Following general procedure A, to a
solution of the methyl 3ꢀmethoxyꢀ4,5ꢀdihydroxybenzoate (2.5 mmol) in acetonitrile (10 ml) was
added potassium carbonate (6.0 mmol) and allyl bromide (6.0 mmol). The mixture was refluxed
overnight and then cooled to room temperature; the precipitate was filtered off and washed with
dichloromethane. The combined filtration was evaporated under vacuum to give the oily crude
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which was further purified with flash chromatography on silica. Elution with hexane/ethyl
1
acetate (5:1ꢀ2:1) gave 4 as colorless oil in 93% yield. H NMR (400 MHz, Chloroformꢀd) δ 7.27
(s, 2H), 6.12 – 5.99 (m, 2H), 5.42 (dq, J = 17.3, 1.6 Hz, 1H), 5.34 – 5.24 (m, 2H), 5.17 (ddt, J =
1
1
1
1
1
1
1
1
1
1
2
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2
2
2
2
2
2
2
2
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5
5
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0.3, 1.9, 1.1 Hz, 1H), 4.59 (ddt, J = 6.1, 5.0, 1.5 Hz, 4H), 3.87 (d, J = 0.7 Hz, 6H). HRMS:
+
calculated for C H O [M+H] 279.1232, found 279.1236.
1
5
19
5
Methyl methyl 3-methoxy-4,5-bis(prop-1-en-1-yloxy)benzoate (5). To a solution of 4 (279
mg, 1.0 mmol) in toluene (5 ml) was added
carbonylchlorohydridotris(triphenylphosphine)ruthenium(II) (95 mg, 0.1 mmol). The mixture
was refluxed for 36 hr. Water was then added and the reaction mixture was extracted with ethyl
acetate, washed with brine and dried with anhydrous Na SO . The combined extracts were
2
4
evaporated under vacuum to give a crude product which was purified with flash chromatography
1
on silica. Elution with hexane/ethyl acetate (8:1ꢀ3:1) gave 5 as colorless oil (218 mg, 78%). H
NMR (400 MHz, Chloroformꢀd) δ 7.35 (s, 2H), 6.47 – 6.11 (m, 2H), 5.44 – 4.60 (m, 2H), 3.90
+
(
d, J = 2.0 Hz, 6H), 1.80 – 1.55 (m, 6H). HRMS: calculated for C H O [M+H] 279.1232,
1
5
19
5
found 279.1234.
Methyl 8-methoxybenzo[b][1,4]dioxine-6-carboxylate (6). To a solution of 5 (200 mg, 0.72
nd
mmol) in toluene (5 ml) was added Grubbs` catalyst 2 generation (95 mg, 0.072 mmol). The
mixture was refluxed for 24 hr. Water was then added and the reaction mixture was extracted
with ethyl acetate, washed with brine and dried with anhydrous Na SO . The combined extracts
2
4
were evaporated under vacuum to give a crude product which was purified with flash
chromatography on silica. Elution with hexane/ethyl acetate (8:1ꢀ3:1) gave 6 as colorless oil (131
1
mg, 82%). H NMR (400 MHz, Chloroformꢀd) δ 7.14 (d, J = 1.9 Hz, 1H), 6.89 (d, J = 1.9 Hz,
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Journal of Medicinal Chemistry
Page 18 of 58
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2
3
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5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
H), 5.91 (d, J = 3.6 Hz, 1H), 5.83 (d, J = 3.6 Hz, 1H), 3.81 (d, J = 0.9 Hz, 6H). HRMS:
+
calculated for C H O [M+H] 223.0606, found 223.0608.
1
1
11
5
8-methoxybenzo[b][1,4]dioxine-6-carboxylic acid (7). Following general procedure B, to a
solution of the methyl benzoate 4 (1.0 mmol) in dioxane (5 ml) was added a solution of lithium
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
o
hydroxide (1.5 mmol) in water (3 ml). The mixture was stirred at 50 C until the TLC indicated
the completion of the reaction. The solvents were removed under reduced pressure and the
resulted residue was partitioned between water (10 ml) and DCM (10 ml), pH value was adjusted
to 5 using 1M HCl solution. The organic solvents were then combined, dried over Na SO ,
2
4
filtered and evaporated under reduced pressure. The crude was purified with flash
chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:1) gave 7 as colorless oil in
1
8
6
4% yield. H NMR (400 MHz, Acetoneꢀd ) δ 7.25 (d, J = 1.8 Hz, 1H), 6.91 (d, J = 1.8 Hz, 1H),
6
.15 (d, J = 3.6 Hz, 1H), 6.12 (d, J = 3.6 Hz, 1H), 3.86 (s, 3H). HRMS: calculated for C H O
5
1
0
9
+
[M+H] 209.0450, found 209.0447.
2
,4,5-tribromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazole (9). To a stirred solution
of 2,4,5ꢀtribromoimidazole (9.5 g, 31.1 mmol) in anhydrous THF (100 ml) at ice temperature
was added sodium hydride (1.5 g, 40.6 mmol) in portions under argon. The mixture was stirred
for 1 h at this temperature and was added 2ꢀ(trimethylsilyl)ethoxymethyl chloride (6.7 ml, 35.8
mmol) dropwise. The reaction was then warmed to room temperature and stirred for another 1.5
hr. Water was then added at ice temperature carefully and the reaction mixture was extracted
with ethyl acetate, washed with brine and dried with Na SO . The combined extracts were
2
4
evaporated under vacuum to give the oily residue which was purified with flash chromatography
on silica. Elution with hexane/ethyl acetate (10:0ꢀ10:1) gave 9 as slightly yellowish solid (12.6 g,
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Page 19 of 58
Journal of Medicinal Chemistry
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5
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7
8
9
1
9
2
3%). H NMR (400 MHz, Chloroformꢀd) δ 5.30 (s, 2H), 3.65 – 3.49 (m, 2H), 0.94 – 0.87 (m,
+
H), ꢀ0.03 (s, 9H). HRMS: calculated for C H Br N OSi [M+H] 432.8582, found 432.8588.
9
16
3
2
3-(4,5-dibromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-2-yl)-1-
phenylsulfonyl)-1H-indole (10). To a mixture of 1ꢀ(Phenylsulfonyl)ꢀ3ꢀindolylboronic acid
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(
pinacol ester (5.0 g, 13.1 mmol), 9 (6.8 g, 15.7 mmol), and sodium carbonate (2.8 g, 26.1 mmol)
in toluene (20 ml), methanol (4 ml) and (1 ml) was added 2ꢀdicyclohexylphosphinoꢀ2′,4′,6′ꢀ
triisopropylbiphenyl (935 mg, 2.0 mmol) and tris(dibenzylideneacetone)dipalladium (600 mg,
0
.66 mmol) under argon. The mixture was refluxed overnight. Water was then added and the
reaction mixture was extracted with ethyl acetate, washed with brine and dried with anhydrous
Na SO . The combined extracts were evaporated under vacuum to give a crude product which
2
4
was purified with flash chromatography on silica. Elution with hexane/ethyl acetate (15:1ꢀ4:1)
1
gave 10 as paleꢀyellow solid in 34% yield. H NMR (400 MHz, Chloroformꢀd) δ 8.20 (s, 1H),
8.17 (dt, J = 7.7, 1.1 Hz, 1H), 8.05 – 8.00 (m, 1H), 7.92 – 7.85 (m, 2H), 7.58 – 7.51 (m, 1H),
7
.47 – 7.36 (m, 3H), 7.32 (td, J = 7.7, 1.1 Hz, 1H), 5.35 (s, 2H), 3.80 – 3.68 (m, 2H), 1.09 – 0.98
+
(
m, 2H), 0.05 (s, 9H). HRMS: calculated for C H Br N O SSi [M+H] 609.9831, found
2
3
26
2
3
3
6
09.9812.
(
4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-
imidazol-5-yl)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methanone (11a). Following general
procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous THF (3.0 ml) under
argon was added isopropylmagnesium chloride lithium chloride complex solution (1.3 M in
THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h and was added
2
,3ꢀdihydrobenzo[b][1,4]dioxineꢀ6ꢀcarbonyl chloride (1.3 mmol) in anhydrous THF (1.0 ml).
The reaction was kept stirring at room temperature for 1 h and then refluxed for 30 min. A
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7
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9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
saturated NH Cl solution was then added to quench the reaction. The reaction mixture was
4
extracted with ethyl acetate, washed with brine and dried with Na SO . The combined extracts
2
4
were evaporated under vacuum to give the crude product which was purified with flash
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
chromatography on silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 11a as paleꢀ
1
yellow solid in 37% yield. H NMR (400 MHz, Chloroformꢀd) δ 8.30 (s, 1H), 8.19 (ddd, J = 7.7,
1
7
2
6
.3, 0.7 Hz, 1H), 8.05 (dt, J = 8.4, 1.0 Hz, 1H), 7.97 – 7.87 (m, 2H), 7.59 – 7.54 (m, 1H), 7.49 –
.32 (m, 6H), 5.62 (s, 2H), 4.42 – 4.33 (m, 2H), 4.30 (dt, J = 5.7, 1.6 Hz, 2H), 3.64 – 3.53 (m,
+
H), 0.98 – 0.90 (m, 2H), ꢀ0.07 (s, 9H). HRMS: calculated for C H BrN O SSi [M+H]
3
2
33
3
6
94.1043, found 694.1063.
Benzo[d][1,3]dioxol-5-yl(4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-
trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-yl)methanone (11b). Following general
(
procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous THF (3.0 ml) under
argon was added isopropylmagnesium chloride lithium chloride complex solution (1.3 M in
THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h and was added
benzo[d][1,3]dioxoleꢀ5ꢀcarbonyl chloride (1.3 mmol) in anhydrous THF (1.0 ml). The reaction
was kept stirring at room temperature for 1 h and then refluxed for 30 min. A saturated NH Cl
4
solution was then added to quench the reaction. The reaction mixture was extracted with ethyl
acetate, washed with brine and dried with Na SO . The combined extracts were evaporated under
2
4
vacuum to give the crude product which was purified with flash chromatography on silica.
Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 11b as paleꢀyellow solid in 31% yield.
1
H NMR (400 MHz, Chloroformꢀd) δ 8.29 (s, 1H), 8.19 (ddd, J = 7.9, 1.4, 0.7 Hz, 1H), 8.05 (dt,
J = 8.3, 1.0 Hz, 1H), 7.95 – 7.87 (m, 2H), 7.59 – 7.50 (m, 2H), 7.49 – 7.32 (m, 5H), 6.90 (dd, J =
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Journal of Medicinal Chemistry
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9
8
9
.2, 1.3 Hz, 1H), 6.10 (s, 2H), 5.62 (s, 2H), 3.66 – 3.50 (m, 2H), 0.99 – 0.90 (m, 2H), ꢀ0.06 (s,
+
H). HRMS: calculated for C H BrN O SSi [M+H] 680.0886, found 680.0871.
3
1
31
3
6
(4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
imidazol-5-yl)(8-methoxy-2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methanone (11c). Following
general procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous THF (3.0
ml) under argon was added isopropylmagnesium chloride lithium chloride complex solution (1.3
M in THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h and was
added 8ꢀmethoxyꢀ2,3ꢀdihydrobenzo[b][1,4]dioxineꢀ6ꢀcarbonyl chloride (1.3 mmol) in anhydrous
THF (1.0 ml). The reaction was kept stirring at room temperature for 1 h and then refluxed for 30
min. A saturated NH Cl solution was then added to quench the reaction. Reaction mixture was
4
extracted with ethyl acetate, washed with brine and dried with Na SO . The combined extracts
2
4
were evaporated under vacuum to give the crude product which was purified with flash
chromatography on silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 11c as paleꢀ
1
yellow solid in 34% yield. H NMR (400 MHz, Chloroformꢀd) δ 8.34 (s, 1H), 8.15 (d, J = 7.8
Hz, 1H), 8.04 (dd, J = 8.4, 1.0 Hz, 1H), 7.97 – 7.89 (m, 2H), 7.56 (t, J = 7.4 Hz, 1H), 7.49 – 7.39
(m, 3H), 7.35 (td, J = 7.6, 1.1 Hz, 1H), 7.20 – 7.11 (m, 3H), 5.62 (s, 2H), 4.41 (dd, J = 3.8, 1.8
Hz, 2H), 4.30 (dd, J = 3.8, 1.8 Hz, 2H), 3.95 (s, 3H), 3.62 – 3.53 (m, 2H), 0.96 – 0.89 (m, 2H), ꢀ
+
0
.08 (s, 9H). HRMS: calculated for C H BrN O SSi [M+H] 724.1148, found 724.1124.
3
3
35
3
7
(4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-
imidazol-5-yl)(7-methoxybenzo[d][1,3]dioxol-5-yl)methanone (11d). Following general
procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous THF (3.0 ml) under
argon was added isopropylmagnesium chloride lithium chloride complex solution (1.3 M in
THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h and was added 3a
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Journal of Medicinal Chemistry
Page 22 of 58
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6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
1.3 mmol) in anhydrous THF (1.0 ml). The reaction was kept stirring at room temperature for 1
h and then refluxed for 30 min. A saturated NH Cl solution was then added to quench the
4
reaction. Reaction mixture was extracted with ethyl acetate, washed with brine and dried with
Na SO . The combined extracts were evaporated under vacuum to give the crude product which
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2
4
was purified with flash chromatography on silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1)
1
gave pure 11d as paleꢀyellow solid in 39% yield. H NMR (400 MHz, Chloroformꢀd) δ 8.30 (s,
1
–
2
H), 8.20 (ddd, J = 7.9, 1.4, 0.7 Hz, 1H), 8.05 (dt, J = 8.2, 1.0 Hz, 1H), 7.94 – 7.90 (m, 2H), 7.60
7.53 (m, 1H), 7.48 – 7.33 (m, 4H), 7.22 (d, J = 1.5 Hz, 1H), 7.12 (d, J = 1.5 Hz, 1H), 6.11 (s,
H), 5.63 (s, 2H), 3.95 (s, 3H), 3.65 – 3.57 (m, 2H), 1.00 – 0.91 (m, 2H), ꢀ0.06 (s, 9H). HRMS:
+
calculated for C H BrN O SSi [M+H] 710.0992, found 710.0979.
3
2
33
3
7
(4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-
imidazol-5-yl)(9-methoxy-3,4-dihydro-2H-benzo[b][1,4]dioxepin-7-yl)methanone (11e).
Following general procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous
THF (3.0 ml) under argon was added isopropylmagnesium chloride lithium chloride complex
solution (1.3 M in THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h
and was added 3b (1.3 mmol) in anhydrous THF (1.0 ml). The reaction was kept stirring at room
temperature for 1 h and then refluxed for 30 min. A saturated NH Cl solution was then added to
4
quench the reaction. The reaction mixture was extracted with ethyl acetate, washed with brine
and dried with Na SO . The combined extracts were evaporated under vacuum to give the crude
2
4
product which was purified with flash chromatography on silica. Elution with hexane/ethyl
1
acetate (10:1ꢀ3:1) gave pure 11e as paleꢀyellow solid in 43% yield. H NMR (400 MHz,
Chloroformꢀd) δ 8.30 (s, 1H), 8.23 – 8.17 (m, 1H), 8.05 (dt, J = 8.4, 1.0 Hz, 1H), 7.94 – 7.89 (m,
2H), 7.60 – 7.53 (m, 1H), 7.49 – 7.32 (m, 4H), 7.22 (d, J = 2.0 Hz, 1H), 7.18 (d, J = 2.0 Hz, 1H),
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Page 23 of 58
Journal of Medicinal Chemistry
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5
6
7
8
9
5
2
.63 (s, 2H), 4.46 (t, J = 5.7 Hz, 2H), 4.30 (t, J = 5.9 Hz, 2H), 3.93 (s, 3H), 3.64 – 3.56 (m, 2H),
.28 (p, J = 5.8 Hz, 2H), 0.99 – 0.90 (m, 2H), ꢀ0.06 (s, 9H). HRMS: calculated for
+
C H BrN O SSi [M+H] 738.1305, found 738.1283.
34
37
3
7
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(4-bromo-2-(1-(phenylsulfonyl)-1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-
imidazol-5-yl)(8-methoxybenzo[b][1,4]dioxin-6-yl)methanone (11f). Following general
procedure D, to a stirred solution of compound 10 (1.0 mmol) in anhydrous THF (3.0 ml) under
argon was added isopropylmagnesium chloride lithium chloride complex solution (1.3 M in
THF, 0.92 ml, 1.2 mmol) at room temperature. The mixture was stirred for 1 h and was added 8
(1.3 mmol) in anhydrous THF (1.0 ml). The reaction was kept stirring at room temperature for 1
h and then refluxed for 30 min. A saturated NH Cl solution was then added to quench the
4
reaction. The reaction mixture was extracted with ethyl acetate, washed with brine and dried with
Na SO . The combined extracts were evaporated under vacuum to give the crude product which
2
4
was purified with flash chromatography on silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1)
1
gave pure 11f as yellowish solid in 48% yield. H NMR (400 MHz, Acetoneꢀd ) δ 8.54 (s, 1H),
6
8
2
1
3
.35 (ddd, J = 8.0, 1.3, 0.7 Hz, 1H), 8.18 – 8.09 (m, 3H), 7.79 – 7.73 (m, 1H), 7.72 – 7.63 (m,
H), 7.52 (ddd, J = 8.4, 7.3, 1.4 Hz, 1H), 7.44 (ddd, J = 8.2, 7.2, 1.1 Hz, 1H), 7.31 (d, J = 1.9 Hz,
H), 6.92 (d, J = 1.9 Hz, 1H), 6.24 (d, J = 3.6 Hz, 1H), 6.20 (d, J = 3.6 Hz, 1H), 5.81 (s, 2H),
.93 (s, 3H), 3.76 – 3.67 (m, 2H), 1.06 – 0.95 (m, 2H), 0.00 (s, 9H). HRMS: calculated for
+
C H BrN O SSi [M+H] 722.0992, found 722.0979.
33
33
3
7
(2-(1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-
yl)(benzo[d][1,3]dioxol-5-yl)methanone (12b). Following general procedure E, to a suspension
of 11b (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine (26 mg,
0.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The mixture
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Page 24 of 58
1
2
3
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5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
was heated to reflux for 4 hr. nꢀBuOH was removed under reduced pressure. The residue was
partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were then
evaporated under reduced pressure. The crude was purified with flash chromatography on silica.
1
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12b as paleꢀyellow solid in 88% yield. H
NMR (400 MHz, Chloroformꢀd) δ 9.35 (s, 1H), 8.30 – 8.17 (m, 1H), 7.94 (d, J = 2.8 Hz, 1H),
7
6
0
.74 (s, 1H), 7.51 (dd, J = 8.1, 1.7 Hz, 1H), 7.41 (dd, J = 7.2, 1.7 Hz, 2H), 7.29 – 7.18 (m, 3H),
.91 (d, J = 8.1 Hz, 1H), 6.08 (s, 2H), 5.88 (s, 2H), 3.78 – 3.64 (m, 2H), 1.00 – 0.86 (m, 2H), ꢀ
+
.06 (s, 9H). HRMS: calculated for C H N O Si [M+H] 462.1849, found 462.1842.
2
5
28
3
4
(2-(1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-yl)(8-methoxy-2,3-
dihydrobenzo[b][1,4]dioxin-6-yl)methanone (12c). Following general procedure E, to a
suspension of 11c (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine
(26 mg, 0.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The
mixture was heated to reflux for 4 hr. nꢀBuOH was removed under reduced pressure. The residue
was partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were
then evaporated under reduced pressure. The crude was purified with flash chromatography on
silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12c as paleꢀyellow solid in 76%
1
yield. H NMR (400 MHz, Chloroformꢀd) δ 9.24 (s, 1H), 8.19 (d, J = 7.2 Hz, 1H), 7.95 (s, 1H),
7
.81 (s, 1H), 7.50 – 7.42 (m, 1H), 7.30 – 7.20 (m, 2H), 7.18 (d, J = 2.0 Hz, 1H), 7.11 (d, J = 2.0
Hz, 1H), 5.88 (s, 2H), 4.42 (dd, J = 3.9, 1.7 Hz, 2H), 4.33 (dd, J = 3.7, 1.7 Hz, 2H), 3.96 (s, 3H),
3.77 – 3.64 (m, 2H), 1.00 – 0.87 (m, 2H), ꢀ0.05 (s, 9H). HRMS: calculated for C H N O Si
2
7
32
3
5
+
[
M+H] 506.2111, found 506.2123.
(2-(1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-yl)(7-
methoxybenzo[d][1,3]dioxol-5-yl)methanone (12d). Following general procedure E, to a
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suspension of 11d (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine
(26 mg, 0.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The
mixture was heated to reflux for 4 hr. nꢀBuOH was removed under reduced pressure. The residue
was partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were
then evaporated under reduced pressure. The crude was purified with flash chromatography on
silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12d as paleꢀyellow solid in 89%
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
yield. H NMR (400 MHz, Chloroformꢀd) δ 8.79 (s, 1H), 8.35 – 8.25 (m, 1H), 8.03 (d, J = 2.8
Hz, 1H), 7.77 (s, 1H), 7.46 – 7.42 (m, 1H), 7.30 – 7.27 (m, 1H), 7.20 (d, J = 1.5 Hz, 1H), 7.13 (d,
J = 1.5 Hz, 1H), 6.10 (s, 2H), 5.91 (s, 2H), 3.96 (s, 3H), 3.80 – 3.70 (m, 2H), 0.94 (d, J = 8.3 Hz,
+
2H), ꢀ0.05 (s, 9H). HRMS: calculated for C H N O Si [M+H] 492.1955, found 492.1950.
2
6
30
3
5
(2-(1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-yl)(9-methoxy-3,4-
dihydro-2H-benzo[b][1,4]dioxepin-7-yl)methanone (12e). Following general procedure E, to a
suspension of 11e (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine
(26 mg, 0.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The
mixture was heated to reflux for 4 h. nꢀBuOH was removed under reduced pressure. The residue
was partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were
then evaporated under reduced pressure. The crude was purified with flash chromatography on
silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12e as paleꢀyellow solid in % 85%
1
yield. H NMR (400 MHz, Chloroformꢀd) δ 8.66 (s, 1H), 8.36 – 8.23 (m, 1H), 8.05 (d, J = 2.8
Hz, 1H), 7.79 (s, 1H), 7.51 – 7.40 (m, 1H), 7.33 – 7.24 (m, 4H), 7.22 (d, J = 2.1 Hz, 1H), 7.16 (d,
J = 2.0 Hz, 1H), 5.92 (s, 2H), 4.44 (t, J = 5.7 Hz, 2H), 4.32 (t, J = 5.9 Hz, 2H), 3.92 (s, 3H), 3.81
–
3.71 (m, 2H), 2.34 – 2.20 (m, 2H), 1.00 – 0.91 (m, 2H), ꢀ0.04 (s, 9H). HRMS: calculated for
+
C H N O Si [M+H] 520.2268, found 520.2262.
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2
2
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(
2-(1H-indol-3-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazol-5-yl)(8-
methoxybenzo[b][1,4]dioxin-6-yl)methanone (12f). Following general procedure E, to a
suspension of 11f (0.5 mmol), potassium carbonate (276 mg, 2.0 mmol), and triphenylphosphine
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(
26 mg, 0.1 mmol) in nꢀBuOH (3 ml) was added palladium acetate (5.6 mg, 0.025 mmol). The
mixture was heated to reflux for 4 hr. nꢀBuOH was removed under reduced pressure. The residue
was partitioned between water (10 ml) and EtOAc (10 ml). The combined organic solvents were
then evaporated under reduced pressure. The crude was purified with flash chromatography on
silica. Elution with hexane/ethyl acetate (10:1ꢀ3:1) gave pure 12f as yellowish solid in 79%
1
yield. H NMR (400 MHz, Chloroformꢀd) δ 10.02 (d, J = 2.8 Hz, 1H), 8.36 – 8.27 (m, 1H), 7.94
(d, J = 2.8 Hz, 1H), 7.87 (s, 1H), 7.38 – 7.31 (m, 1H), 7.30 – 7.22 (m, 2H), 7.16 (d, J = 1.9 Hz,
1
H), 6.95 (d, J = 1.9 Hz, 1H), 6.04 (d, J = 3.6 Hz, 1H), 5.98 – 5.88 (m, 3H), 3.92 (s, 3H), 3.83 –
+
3
.67 (m, 2H), 1.03 – 0.89 (m, 2H), 0.00 (s, 9H). HRMS: calculated for C H N O Si [M+H]
2
7
30
3
5
504.1955, found 504.1932.
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)methanone
(
13a). Following general procedure F, to a solution of 12a (0.3 mmol) in DCM (1 ml) was added
trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and solvent was evaporated under
reduced pressure. The residue was partitioned between saturated NaHCO solution and EtOAc.
3
The combined organic solvents were then evaporated under reduced pressure. The crude was
purified with flash chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:2) gave
1
pure 13a as yellowish solid in 88% yield. H NMR (400 MHz, DMSOꢀd ) δ 13.14 (s, 1H), 11.62
6
(
s, 1H), 8.47 – 8.36 (m, 1H), 8.30 – 8.17 (m, 1H), 7.87 (s, 1H), 7.68 (s, 2H), 7.48 (dt, J = 8.2, 0.9
1
3
Hz, 1H), 7.25 – 7.12 (m, 2H), 7.04 (d, J = 8.8 Hz, 1H), 4.52 – 4.27 (m, 4H). C NMR (101
MHz, DMSOꢀd ) δ 182.34, 147.19, 143.08, 136.31, 131.36, 125.85, 124.94, 122.99, 122.13,
6
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21.06, 120.17, 118.17, 116.93, 111.84, 105.51, 64.50, 64.01. HRMS: calculated for C H N O
3
2
0
16
3
+
[
M+H] 346.1192, found 346.1205. Purity: 100.0% by HPLC.
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(benzo[d][1,3]dioxol-5-yl)methanone (13b). Following
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
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3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
general procedure F, to a solution of 12b (0.3 mmol) in DCM (1 ml) was added trifluoroacetic
acid (1 ml). The reaction was stirred for 2 h and solvent was evaporated under reduced pressure.
The residue was partitioned between saturated NaHCO solution and EtOAc. The combined
3
organic solvents were then evaporated under reduced pressure. The crude was purified with flash
chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:2) gave pure 13b as
1
yellowish solid in 92% yield. H NMR (400 MHz, DMSOꢀd ) δ 13.36 (s, 1H), 11.67 (s, 1H),
6
8.42 – 8.32 (m, 1H), 8.23 (d, J = 2.7 Hz, 1H), 7.92 (s, 1H), 7.81 (d, J = 7.1 Hz, 1H), 7.71 – 7.56
(m, 1H), 7.49 (dt, J = 8.2, 0.9 Hz, 1H), 7.19 (dtd, J = 17.2, 7.1, 1.3 Hz, 2H), 7.11 (d, J = 8.1 Hz,
1
3
1
H), 6.18 (s, 2H). C NMR (101 MHz, DMSOꢀd ) δ 182.19, 150.85, 147.53, 136.31, 132.20,
6
126.18, 125.20, 124.82, 122.20, 120.93, 120.25, 111.90, 108.79, 108.03, 105.05, 101.88. HRMS:
+
calculated for C H N O [M+H] 332.1035, found 332.1050. Purity: 97.5% by HPLC.
1
9
14
3
3
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(8-methoxy-2,3-dihydrobenzo[b][1,4]dioxin-6-
yl)methanone (13c). Following general procedure F, to a solution of 12c (0.3 mmol) in DCM (1
ml) was added trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and solvent was
evaporated under reduced pressure. The residue was partitioned between saturated NaHCO3
solution and EtOAc. The combined organic solvents were then evaporated under reduced
pressure. The crude was purified with flash chromatography on silica. Elution with hexane/ethyl
1
acetate (4:1ꢀ1:2) gave pure 13c as yellowish solid in 79% yield. H NMR (400 MHz,
Chloroformꢀd) δ 8.02 (s, 1H), 7.92 (s, 1H), 7.81 (s, 1H), 7.40 (dd, J = 10.9, 7.7 Hz, 1H), 7.16
1
3
(dd, J = 7.0, 3.0 Hz, 3H), 7.07 (s, 1H), 4.41 – 4.32 (m, 2H), 4.32 – 4.22 (m, 2H), 3.91 (s, 3H). C
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2
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2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
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5
5
5
5
5
5
5
5
6
NMR (101 MHz, Chloroformꢀd) δ 182.90, 149.30, 147.56, 143.77, 137.96, 136.52, 130.62,
1
29.30, 128.47, 124.17, 123.16, 121.50, 119.33, 112.37, 112.24, 104.74, 102.80, 64.99, 64.18,
+
56.44. HRMS: calculated for C H N O [M+H] 376.1297, found 376.1309. Purity: 98.2% by
2
1
18
3
4
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
HPLC.
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(7-methoxybenzo[d][1,3]dioxol-5-yl)methanone
(13d). Following general procedure F, to a solution of 12d (0.3 mmol) in DCM (1 ml) was added
trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and solvent was evaporated under
reduced pressure. The residue was partitioned between saturated NaHCO solution and EtOAc.
3
The combined organic solvents were then evaporated under reduced pressure. The crude was
purified with flash chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:2) gave
1
pure 13d as yellowish solid in 85% yield. H NMR (400 MHz, Chloroformꢀd) δ 8.16 – 8.07 (m,
1
H), 7.90 (s, 1H), 7.74 (s, 1H), 7.46 – 7.37 (m, 1H), 7.25 – 7.20 (m, 3H), 7.14 (d, J = 1.5 Hz,
1
3
1H), 6.06 (s, 2H), 3.93 (s, 3H). C NMR (101 MHz, Chloroformꢀd) δ 182.72, 148.95, 148.33,
1
1
3
43.59, 139.51, 136.49, 132.27, 130.88, 126.65, 124.37, 122.93, 121.26, 119.79, 111.98, 109.78,
+
05.09, 103.46, 102.39, 56.68. HRMS: calculated for C H N O [M+H] 362.1141, found
2
0
16
3
4
62.1146. Purity: 99.7% by HPLC.
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(9-methoxy-3,4-dihydro-2H-benzo[b][1,4]dioxepin-7-
yl)methanone (13e). Following general procedure F, to a solution of 12e (0.3 mmol) in DCM (1
ml) was added trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and solvent was
evaporated under reduced pressure. The residue was partitioned between saturated NaHCO3
solution and EtOAc. The combined organic solvents were then evaporated under reduced
pressure. The crude was purified with flash chromatography on silica. Elution with hexane/ethyl
1
acetate (4:1ꢀ1:2) gave pure 13e as yellowish solid in 80% yield. H NMR (400 MHz,
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Chloroformꢀd) δ 8.16 (dd, J = 6.5, 2.9 Hz, 1H), 7.87 (d, J = 3.0 Hz, 1H), 7.74 (d, J = 3.4 Hz, 1H),
7
.62 – 7.48 (m, 1H), 7.42 (dt, J = 6.0, 3.0 Hz, 1H), 7.25 – 7.20 (m, 2H), 7.20 – 7.13 (m, 1H),
1
3
4.38 (t, J = 5.8 Hz, 2H), 4.34 – 4.23 (m, 2H), 3.89 (s, 3H), 2.24 (dd, J = 7.0, 4.5 Hz, 2H). C
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
NMR (101 MHz, Chloroformꢀd) δ 183.11, 151.77, 151.18, 144.62, 136.51, 132.03, 131.93,
1
31.78, 128.67, 128.55, 126.17, 124.48, 122.84, 121.17, 119.92, 115.51, 111.88, 106.65, 70.82,
+
7
0.50, 56.37, 30.97. HRMS: calculated for C H N O [M+H] 390.1454, found 390.1472.
22 20
3
4
Purity: 100.0% by HPLC.
(2-(1H-indol-3-yl)-1H-imidazol-5-yl)(8-methoxybenzo[b][1,4]dioxin-6-yl)methanone (13f).
Following general procedure F, to a solution of 12f (0.3 mmol) in DCM (1 ml) was added
trifluoroacetic acid (1 ml). The reaction was stirred for 2 h and solvent was evaporated under
reduced pressure. The residue was partitioned between saturated NaHCO solution and EtOAc.
3
The combined organic solvents were then evaporated under reduced pressure. The crude was
purified with flash chromatography on silica. Elution with hexane/ethyl acetate (4:1ꢀ1:2) gave
1
pure 13f as yellowish solid in 84% yield. H NMR (400 MHz, DMSOꢀd ) δ 13.02 (s, 1H), 11.55
6
(s, 1H), 8.40 (d, J = 7.8 Hz, 1H), 7.94 (s, 2H), 7.47 (d, J = 7.9 Hz, 1H), 7.16 (dtd, J = 16.1, 8.1,
1
3
7
.6, 6.4 Hz, 2H), 6.30 (d, J = 9.2 Hz, 2H), 3.88 (s, 3H). C NMR (101 MHz, Chloroformꢀd) δ
1
83.83, 153.01, 148.97, 141.70, 136.51, 133.30, 126.13, 124.53, 122.77, 121.05, 120.00, 111.88,
+
1
06.31, 105.74, 56.18. HRMS: calculated for C H N O [M+H] 374.1141, found 374.1157.
2
1
16
3
4
Purity: 99.4% by HPLC.
4-bromo-1-(phenylsulfonyl)-1H-indole (14). To a solution of 4ꢀbromoindole (1.0 g, 5.1
mmol) in THF (10 ml) was added sodium hydride (314 mg, 7.6 mmol) in portions under ice
temperature. After 1 h, benzenesulfonyl chloride (0.81 ml, 6.1 mmol) was added dropwise. The
reaction was stirred at room temperature for 2 h. Water was then added and the reaction mixture
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