Identification of novel non-nucleoside vinyl-stilbene analogs as potent norovirus replication inhibitors with a potential host-targeting mechanism

Article abstract of DOI:10.1016/j.ejmech.2019.111733

Norovirus (NV), is the most common cause of acute gastroenteritis worldwide. To date, there is no specific anti-NV drug or vaccine to treat NV infections. In this study, we evaluated the inhibitory effect of different stilbene-based analogs on RNA genome replication of human NV (HNV) using a virus replicon-bearing cell line (HG23). Initial screening of our in-house chemical library against NV led to the identification of a hit containing stilbene scaffold 5 which on initial optimization gave us a vinyl stilbene compound 16c (EC₅₀ = 4.4 μM). Herein we report our structure-activity relationship study of the novel series of vinyl stilbene analogs that inhibits viral RNA genome replication in a human NV-specific manner. Among these newly synthesized compounds, several amide derivatives of vinyl stilbenes exhibited potent anti-NV activity with EC₅₀ values ranging from 1 to 2 μM. A trans-vinyl stilbenoid with an appended substituted piperazine amide (18k), exhibited potent anti-NV activity and also displayed favorable metabolic stability. Compound 18k demonstrated an excellent safety profile, the highest suppressive effect, and was selective for HNV replication via a viral RNA polymerase-independent manner. Its potential host-targeting antiviral mechanism was further supported by specific activation of heat shock factor 1-dependent stress-inducible pathway by 18k. These results suggest that 18k might be a promising lead compound for developing novel NV inhibitors with the novel antiviral mechanism.

Full text of DOI:10.1016/j.ejmech.2019.111733

Journal Pre-proof
Identification of novel non-nucleoside vinyl-stilbene analogs as potent norovirus
replication inhibitors with a potential host-targeting mechanism
Dipesh S. Harmalkar, Sung-Jin Lee, Qili Lu, Mi Il Kim, Jaehyung Park, Hwayoung
Lee, Minkyung Park, Ahrim Lee, Choongho Lee, Kyeong Lee
PII:
S0223-5234(19)30885-2
DOI:
https://doi.org/10.1016/j.ejmech.2019.111733
EJMECH 111733
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 5 August 2019
Revised Date: 16 September 2019
Accepted Date: 22 September 2019
Please cite this article as: D.S. Harmalkar, S.-J. Lee, Q. Lu, M.I. Kim, J. Park, H. Lee, M. Park, A.
Lee, C. Lee, K. Lee, Identification of novel non-nucleoside vinyl-stilbene analogs as potent norovirus
replication inhibitors with a potential host-targeting mechanism, European Journal of Medicinal
Chemistry (2019), doi: https://doi.org/10.1016/j.ejmech.2019.111733.
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Graphical abstract
1

Identification of Novel Non-Nucleoside Vinyl-Stilbene Analogs as
Potent Norovirus Replication Inhibitors with a Potential Host-
Targeting Mechanism
Dipesh S. Harmalkar, Sung-Jin Lee, Qili Lu, Mi Il Kim, Jaehyung Park, Hwayoung Lee,
Minkyung Park, Ahrim Lee, Choongho Lee* and Kyeong Lee*
College of Pharmacy, Dongguk University-Seoul, Goyang, 10326, Republic of Korea
E-mail: choongholee@dongguk.edu; E-mail: kaylee@dongguk.edu
1

Abstract
Norovirus (NV), is the most common cause of acute gastroenteritis worldwide. To date, there is
no specific anti-NV drug or vaccine to treat NV infections. In this study, we evaluated the
inhibitory effect of different stilbene-based analogs on RNA genome replication of human NV
(HNV) using a virus replicon-bearing cell line (HG23). Initial screening of our in-house
chemical library against NV led to the identification of a hit containing stilbene scaffold 5 which
on initial optimization gave us a vinyl stilbene compound 16c (EC50 = 4.4 ꢀM). Herein we report
our structure-activity relationship study of the novel series of vinyl stilbene analogs that inhibits
viral RNA genome replication in a human NV-specific manner. Among these newly synthesized
compounds, several amide derivatives of vinyl stilbenes exhibited potent anti-NV activity with
EC50 values ranging from 1 to 2 ꢀM. A trans-vinyl stilbenoid with an appended substituted
piperazine amide (18k), exhibited potent anti-NV activity and also displayed favorable metabolic
stability. Compound 18k demonstrated an excellent safety profile, the highest suppressive effect,
and was selective for HNV replication via a viral RNA polymerase-independent manner. Its
potential host-targeting antiviral mechanism was further supported by specific activation of heat
shock factor 1-dependent stress-inducible pathway by 18k. These results suggest that 18k might
be a promising lead compound for developing novel NV inhibitors with the novel antiviral
mechanism.
2

Keywords: Norovirus, Inhibitors, Non-nucleoside, Vinyl-Stilbenes, HSF-1.
3

1. Introduction
Norovirus (NV) is a single-stranded positive-sense RNA (7.4–7.7 kb) virus belonging to the
Caliciviridae family [1]. Human NV (HNV), in the genus NV, is the leading causative agent of
epidemic gastroenteritis worldwide. NV infections can occur year round with very high
morbidity and mortality in immunocompromised patients, young children, and older people
[2,3]. HNVs are extremely stable in the environment, highly contagious, and generally
transmitted via the fecal-oral route upon contamination of food products, water, or fomites [4].
According to a Centers for Disease Control and Prevention survey, NV causes approximately
200,000 deaths annually worldwide, and every year is estimated to cost $60 billion worldwide
due to healthcare costs and lost productivity [5].
NVs are phylogenetically divided into six genogroups (GI−GVI). HNV belongs to
genogroup II (GII) and genotype 4 (GII.4), accounting for many of the global outbreaks. The NV
genome consists of three open reading frames (ORF1–3). ORF1 encodes a large 200 kDa
polyprotein that is cleaved by the virally encoded protease (NS6) to produce six nonstructural
proteins. Among these nonstructural proteins, the viral protease (NS6) and RNA-dependent RNA
polymerase (RdRp, NS7) play a critical role in viral RNA genome replication and hence have
been attractive targets for discovering NV-specific therapeutics [6,7]. X-ray crystal structures of
these proteins have provided a much-needed platform for the design and identification of small
molecule NV inhibitors [8]. They include a peptidomimetic protease (NS6) inhibitor
(rupintravir), nucleoside RdRp (NS7) inhibitors (2’-(2’-C-methylcytidine (2CMC) and ribavirin)
and non-nucleoside RdRp (NS7) inhibitors (suramin and pyridoxal-5-phosphate-6-(2-
naphthylazo-6-nitro-4,8-disulfonate tetrasodium salt (PPNDS)) (Fig. 1) [9-12].
4

To date, there have been no specific drugs or vaccines to treat NV infections; thus, there is a
pressing need to develop effective anti-NV therapeutics. CMX521 is the first nucleoside in
clinical development for the treatment and prevention of NV, which was developed by Chimerix.
CMX521 is active in vitro against all strains of NVs tested to date and has a promising safety
profile with high safety margins for human exposure [13]. In addition, the non-nucleoside drug
nitazoxanide has demonstrated efficacy against NV infection in clinical trials. However, the
exact mode of action of nitazoxanide against NV remains elusive (Fig. 1) [14,15].
Insert Figure 1
Phytochemicals such as curcumin and resveratrol have displayed antiviral effects against NV
when evaluated using murine norovirus (MNV) and feline calicivirus (FCV) as surrogate models
for NV biology. However, neither of these phytochemicals displays a strong inhibitory effect on
HNV replication [16]. Very few reports are available on stilbene analogs with anti-NV activity.
We have recently accomplished total synthesis of stilbene-based natural product gramisitlbenoids
A (1), B (2), and C (3) [17]. As part of our drug development program, our in-house chemical
library containing these natural products and their synthetic analogs (4−6) were evaluated for
different biological assays including anti-NV activity (Fig. 2). Among them, stilbenoid 5 with a
vinyl moiety exhibited moderate inhibitory activity against NV replication. Considering 5 as a
hit, derivatives of this compound were synthesized to perform a structure-activity relationship
(SAR) study. Here, we report the design, synthesis, and biological activity of non-nucleoside
stilbene-based NV replication inhibitors.
Insert Figure 2
5

2. Results and discussion
2.1 Chemistry
A series of vinyl stilbene analogs were synthesized as depicted in Schemes 1−4. The benzyl
bromides 7a,b on Arbuzav reaction gave phosphonate esters 8a,b which underwent HWE
olefination in the presence of NaH as a base with corresponding aldehydes to give selectively
(E)-bromostilbenes 9a,b. Compounds 9a,b on Stille coupling yielded vinyl stilbenes 10a,b,
following the previous reports [17]. Compound 11 bearing hydroxyl ethyl moiety was
synthesized from compound 10a via the hydroboration-oxidation reaction. Additionally, (E)-
stilbenes 12a,b were synthesized using a synthetic route similar to 9a,b (Scheme 1).
Insert Scheme 1
Similarly, (E)-stilbenes 15a–f were synthesized from phosphonate esters 14a–f and 4-bromo-
3,5-dimethoxybenzaldehyde using HWE olefination. The ester group was hydrolyzed during
HWE olefination to give acid analog 15f, which was again methylated using MeI in the presence
of K2CO3 to yield 15g. Furthermore, Stille coupling on 15a–e and 15g afforded vinyl stilbenes
16a–e and 16g, respectively. The vinyl stilbene acid analog 16f was obtained by hydrolysis of
16g using LiOH (Scheme 2).
Insert Scheme 2
Compound 16f on esterification with commercially available benzyl bromides in the
presence of K2CO3 yielded ester derivatives 17a–d (Scheme 3). The amide analogs 18a–m were
6

synthesized from 16f by coupling various amines under standard coupling conditions (Scheme
3).
Insert Scheme 3
To synthesize the cis-analogue 24a, Wittig salt 19 was prepared from methyl 4-
(bromomethyl)benzoate (13f) using PPh3 and toluene as the solvent [18]. The obtained salt 19
was subjected to the Wittig reaction with 4-bromo-3,5-dimethoxybenzaldehyde in the presence
of NaH to give both the (E)- (15g) and (Z)- (20) isomers in a 1:1 ratio, which were separated
using column chromatography and confirmed by NMR studies. Pd/C hydrogenation on 20
provided saturated compound 21. Stille coupling on compounds 20 and 21 afforded vinyl
stilbenes 22a,b. Basic hydrolysis to obtain 23a,b and succeeding the amide coupling reaction
with [4-(Trifluoromethyl)benzyl]piperazine in the presence of HATU yielded desired
compounds 24a,b. (Scheme 4).
Insert Scheme 4
7

2.2 Structure-Activity Relationship Studies
In search of more potent and efficient NV inhibitors, we evaluated the inhibitory effect of
different stilbene-based analogues on the RNA genome replication by using a human NV
replicon-bearing cell line (HG23), which is the only available in vitro human NV screening tool
due to the inability to culture infectious NV in vitro. 2CMC was used as a reference compound.
Initial screening of the compounds suggested that gramistilbenoid C (3), and intermediates 4 and
6 did not inhibit NV replication; however, vinyl stilbene 5 inhibited more than half of NV
replication at 10 ꢀM (Table 1). Based on these results, the SAR study of gramistilbenoids was
approached in a systematic manner in which the molecule was divided into four regions, as
shown in Fig. 3.
Insert Figure 3
To improve anti-NV activity, we carried out structural modifications of compound 5 via an
empirical medicinal chemistry approach. We first explored the influence of the substitution
pattern of methoxy and vinyl groups on compound 5 (Table 1). Bromostilbene compound 9a did
not show any anti-NV activity. Compound 10a possessing a vinyl group displayed >70% NV
inhibition whereas vinyl stilbene 10b with –OMe groups on ring B drastically decreased
inhibition. Additionally, natural product mimic 11 without –OMe groups was evaluated and
showed moderate inhibitory activity against NV. Furthermore, to validate the importance of the
vinyl moiety on compound 5, compounds 12a (without a vinyl moiety) and 12b (with an ethyl
moiety) were evaluated. Of note, these compounds exhibited a distinct loss of anti-NV activity,
suggesting that vinyl stilbene scaffold may be optimal for inhibitory activity against NV
replication (Table 1).
8

Insert Table 1
Taken together with previous results, ring A was kept intact and the para position of ring B
was explored, therefore, replacement of the -H atom at the para position with functional groups
such as -F, -CF3, -CO2H, and -CO2Me was carried out (Table 2). Compound 16a with a fluorine
atom showed moderate NV inhibition whereas a MOM ether linker (16b) exhibited no activity.
Interestingly, introduction of a -CF3 (16c) at the para position greatly enhanced NV inhibition
(81%) with reduced toxicity. However, orienting -CF3 to the ortho (16d) and meta (16e)
positions resulted in complete loss of potency. The carboxylic acid (16f) and ester (16g) analogs
were also inactive (Table 2). This vinyl stilbene series suggested that -OMe groups and a vinyl
moiety on ring A and para substitution on ring B were critical for antiviral potency. The -CF3
substituted vinyl stilbene 16c was more potent, indicating that subtle structural modification
could greatly improve antiviral activity. Compound 16c afforded our first significant gain in
potency and was used as a launching pad for the design and synthesis of more vinyl stilbene
analogs.
Insert Table 2
Given the encouraging potency of compound 16c, ring A was kept intact and -CF3 was
replaced with an ester motif at the para position of ring B. The carboxylic ester analogs 17a–d
did not significantly improve potency suggesting that incorporation of the ester linkage was
detrimental to anti-NV activity (Table 3). Hence, the introduction of an amide linkage at the para
position of ring B was envisaged and accordingly amide analogs 18a−k were synthesized
(Tables 3).
9

The furfuryl amine compound 18a with one carbon linker inhibited NV replication by 66%,
whereas the allylamine analog 18b and the 4-trifluoromethyl anilide 18c exhibited poor NV
inhibitory activity. 2-Phenylethanamine compound 18d with two carbon linkers inhibited NV by
72%. Furthermore, replacing the benzene ring of 18d with a heterocycle (e.g. pyridine,
compounds 18e and 18f) enhanced the NV inhibition. Both compounds 18e and 18f inhibited
NV replication by 85% and 87% respectively, with better cell viability. The pyridine ring led to
active compounds, further stressing that these groups may involve in hydrogen bonding with its
target protein; however, the position of the pyridine-nitrogen atom is not a major factor for
potency. Amide analogs of tyramine (18g) and tryptamine (18h) also displayed moderate NV
inhibitory activity (Table 3). Based on this analysis, amide linkage with a two carbon linker and
nitrogen-containing moieties are advantageous in term of potency and log P (Appendix A, Table
S1). In another approach, the carbon linker was replaced with the conformationlly locked
piperazine motif to give compounds 18i−k (Table 3). Among them, compound 18i with
isopropyl piperazine was found to be toxic and displayed low NV inhibitory activity, and
compound 18j with 2-(piperazine-1-yl)ethanol did not show any anti-NV activity. Interestingly,
compound 18k possessing the 1-(4-(trifluoromethyl)benzyl)piperazine moiety showed excellent
inhibition of NV replication by 95.8%.
The least toxicity and highest suppressive effect of compound 18k on virus replication
prompted us to quantify the effect of substituted piperazine on anti-NV activity. Hence, a series
of extended piperazine analogues were prepared in an attempt to further drive potency (Table 3,
compounds 18l,m and 24a,b). However, in contrast to compound 18k, compound 18l with fluoro
and 18m with the electron donating –OMe group behaved very differently against NV
replication and did not show the same degree of potency, instead resulting in increased toxicity.
10

Lastly, to validate the importance of trans geometry of potent compound 18k, its cis isomer 24a
and saturated analog 24b were synthesized. Both these compounds exhibited poor NV activity
emphasizing the importance of the trans double bond (Table 3).
Insert Table 3
2.3 Dose-dependent Response on Cell Viability, NV Replication, and Protein Expression
The dose-dependent response of selected vinyl stilbene analogs on cell viability, NV genome
replication, and protein expression is summarized in Table 4. Compound 16c was equipotent
with 2CMC having an EC50 value 4.4 µM with a CC50 value > 10 µM. Amide analogs 18e, 18f,
and 18k showed promising results, exhibiting EC50 values of 2.0, 1.44, and 2.43 µM
respectively; with a CC50 value > 100 µM (Fig. 4A). In particular, 0.8 µM of 18k was able to
block the 50% of the neomycin phosphotransferase expression from the NV replicon in HG23
cells when treated for 5 days (Fig. 4B). Compounds 18e, 18f, and 18k had higher therapeutic
index (TI) (50.0, 69.0, and 41.2, respectively) than 2CMC (TI = 3.1) indicating a superior safety
profile with respect to the reference compound. Among them, 18k showed the most complete
suppression of NV replication at the highest concentration (10 µM) as judged by RT-PCR and
western blot analysis (Fig. 4B).
Insert Table 4
Insert Figure 4
2.4 Effects of Representative Compounds 18e, 18f, and 18k on HNV RdRp Activity
11

To test the potential effects of 18e, 18f, and 18k on enzymatic activity of the HNV RdRp
protein, we performed an in vitro RNA polymerase assay at 10 µM. As shown in Fig. 5, no
significant effects were detected, indicating that the antiviral activities of 18e, 18f, and 18k do
not depend on any direct inhibition of HNV RNA polymerase. In line with this evidence, we
failed to isolate 18k-resistant HNV genome-containing HG23 cells in the presence of escalating
doses of 18k up to 10 µM (data not shown). This relatively high resistance barrier suggests
potential targeting of host proteins by 18k for its antiviral activity.
Insert Figure 5
2.5 Microsomal Stability of Representative Compounds 18e, 18f, and 18k
Many pharmacological compounds encounter formidable challenges to their metabolic
stability in vivo, which is broadly considered a significant parameter in drug discovery. To assess
the drug-likeliness of this series of analogs, we determined the metabolic stability of the potent
compounds 18e, 18f, and 18k (Table 5). The in vitro metabolic stabilities of these analogs were
examined by measuring the percentage remaining during a 30 min upon incubation with human
and mouse liver microsomes in the presence of an NADPH regeneration system. Verapamil was
used as a reference compound. Compound 18e exhibited poor stability against human liver
microsomes; however, it showed good stability against mouse liver microsomes in the presence
of cofactor NADPH. Compound 18f showed poor metabolic stability in human and mouse liver
microsomes. In contrast, 18k had the highest stability in both human and mouse liver
microsomes in the presence of the cofactor NADPH. Moreover, no significant change was
observed in the 18e, 18f, and 18k concentrations during the microsomal incubations in the
12

absence of NADPH. Considering that metabolic stability is one of the major issues for drug
development, these results merit further study of compound 18k as a promising lead.
Insert Table 5
2.6 Effects of 18k on NV Infection Using Surrogate Infectious Models
As there is no infectious model available for HNV, we tested the potential activity of 18k on
MNV-1 and FCV which are surrogate infectious models for HNV. Compound 18k failed to
exhibit any antiviral activity against MNV-1, nevertheless, it exhibited moderate inhibition
against FCV infection at concentrations > 5 µM. These data suggest that 18k inhibits HNV
replication possibly via HNV- and human cell-specific mode of actions (Fig. 6).
Insert Figure 6
2.7 Effect of 18k on Multiple Host Signal Transduction Pathways
To gain insight into the potential antiviral mechanism of action, we studied the effect of 18k
on multiple host signal transduction pathways using a commercially available 45 pathway
reporter array (Table 6). As shown in Fig. 7B, both nuclear factor erythroid 2-related factor 2
(Nrf2)-dependent anti-oxidative and heat shock factor (HSF)-1-dependent stress-inducible
pathways were specifically activated by 18k treatment. This finding suggests the potential
involvement of these two pathways in antiviral action of 18k. However, neither pharmacological
activation nor CRISPR-Cas9-mediated knock-out of the Nrf2 gene induced a significant effect
on HNV replication, ruling out its direct causative role in 18k-induced antiviral effects (data not
shown). Interestingly, 2CMC treatment also induced the activation of HSF-1-dependent
13

signaling pathway (Fig. 7A). In line with this, we were also able to confirm the dose-dependent
induction of HSF-1 protein by 18k treatment (Fig. 7C). We are currently elucidating the potential
role of HSF-1 in the antiviral action of 18k in NV infection.
Insert Table 6
Insert Figure 7
14

3. Conclusions
Based on the identification of hit compound 5, an additional series of structurally-diverse
stilbenoids was synthesized and evaluated, resulting in the identification of novel NV inhibitors
that inhibited NV replication in the very low ꢀM or sub-ꢀM range. Among the synthesized
compounds, the vinyl stilbene scaffold with appended substituted amides, 18e, 18f, and 18k
exhibited excellent anti-NV activity with EC50 values of 2.0, 1.44, and 2.43 ꢀM, respectively and
TIs in the range of 40 to 70. 1-(4-(Trifluoromethyl)benzyl)piperazine amide stilbene 18k was the
least toxic displaying the highest suppressive effect on virus replication. Remarkably, compound
18k inhibited the viral RNA genome replication in a human NV-specific manner. Multiple Host
Signal Transduction pathways studies pointed towards the potential involvement of HSF-1-
dependent stress-inducible pathway which was confirmed by the dose-dependent induction of
HSF-1 protein with 18k treatment. To the best of our knowledge, this is the first example of
host-targeting antivirals directed against NV infection except for the deubiquitinases inhibitor,
WP1130 [19]. Host-targeting nature is an advantageous approach in antiviral therapeutics as it is
less likely to confer drug resistance issues; elucidation of the potential involvement of HSF-1-
dependent pathway in antiviral action of these compounds may greatly facilitate the development
of effective anti-NV therapeutics in the near future.
15

4. Experimental section
4.1 Chemistry
4.1.1 General
All the commercial chemicals were of reagent grade and were used without further
purification. Reactions were conducted under an atmosphere of dried argon in flame-dried
1
glassware. H NMR spectra were determined on a Varian (400 MHz) spectrometer (Varian
1
Medical Systems, Inc., Palo Alto, CA, USA). The H NMR data are reported as peak
multiplicities: s for singlet, d for doublet, dd for doublet of doublets, t for triplet, q for quartet, br
13
for broad singlet, and m for multiplet. C NMR spectra were recorded on a Varian (100 MHz)
spectrometer. The values of the chemical shifts are expressed in δ values (ppm), and the coupling
constants (J) are reported in Hertz (Hz). Mass spectra were recorded using high-resolution mass
spectrometry (HRMS, ESI-MS), obtained on a G2 QTOF mass spectrometer (Waters Corp,
Milford, USA). Products were purified by column or flash chromatography (Biotage, Sweden)
using silica gel 60 (230−400 mesh Kieselgel 60). TLC on 0.25 mm silica plates (E. Merck; silica
gel 60 F254) was used to monitor the reactions. Spots were detected by viewing under UV light
and colorized with charring after dipping in anisaldehyde or basic KMnO4 solution. The purity of
the final products was checked by reversed phase high-pressure liquid chromatography (RP-
HPLC), which was performed on a Waters Corp. HPLC system equipped with an ultraviolet
(UV) detector set at 254 nm. The mobile phases used were (A) H2O containing 0.05%
trifluoroacetic acid and (B) CH3CN. HPLC employed a YMC Hydrosphere C18 (HS-302)
column (5 ꢀm particle size, 12 nm pore size) that was 4.6 mm in diameter × 150 mm in size with
a flow rate of 1.0 mL/min. The compound purity was assessed using a gradient of 25% B to
16

100% B in 35 min. All biologically evaluated compounds purity was > 95%. Detailed synthetic
procedures and spectral characterization for all intermediates are provided in the Supporting
Information.
(E)-5-(3,5-Dimethoxystyryl)-2-(2-hydroxyethyl)benzene-1,3-diol [Gramistilbenoid C (3)].17
1
Compound 3 was obtained as a brown semi-solid (80.0 mg, 58% yield). H NMR (methanol-d4,
400 MHz)
δ 6.94 (d, J = 16.4 Hz, 1H), 6.90 (d, J = 16.4 Hz, 1H), 6.65 (d, J = 2.4 Hz, 2H), 6.49
(s, 2H), 6.38 (t, J = 2.2 Hz, 1H), 3.79 (s, 6H), 3.46 (t, J = 8.4 Hz, 2H), 3.14 (t, J = 8.4 Hz, 2H);
13C NMR (methanol-d4, 100 MHz)
δ
162.5, 157.8, 140.8, 138.3, 130.3, 129.1, 113.6, 105.8,
105.4, 100.7, 55.8, 31.4, 28.9; HRMS (ESI) m/z calcd for C18H21O5 [M + H]+ 317.1389, found
317.1408; RP-HPLC purity 92% at 254 nm, tR = 16.48 min.
(E)-2-Bromo-5-(3,5-dimethoxystyryl)-1,3-dimethoxybenzene (4).17 Compound 4 was obtained as
a white solid (3.90 g, 66% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.05 (d, J = 16.4 Hz, 1H), 7.00
(d, J = 16.0 Hz, 1H), 6.71 (s, 2H), 6.68 (d, J = 2.4 Hz, 2H), 6.42 (t, J = 2.4 Hz, 1H), 3.95 (s, 6H),
3.83 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ
161.1, 157.2, 138.8, 137.6, 129.5, 128.7, 104.7,
102.9, 100.5, 100.4, 56.5, 55.4; HRMS (ESI) m/z calcd for C18H20BrO4 [M + H]+ 379.0545,
found 379.0606; RP-HPLC purity 99% at 254 nm, tR = 22.28 min.
(E)-5-(3,5-Dimethoxystyryl)-1,3-dimethoxy-2-vinylbenzene (5).17 Compound 5 was obtained as a
1
light green solid (0.35 g, 88% yield). H NMR (CDCl3, 400 MHz)
δ 7.02 (s, 2H), 6.97 (dd, J =
17.8, 12.2 Hz, 1H), 6.69 (s, 2H), 6.67 (d, J = 2.0 Hz, 2H), 6.40 (s, 1H), 6.10 (dd, J = 18.0, 2.8
Hz, 1H), 5.44 (dd, J = 12.2, 2.6 Hz, 1H), 3.90 (s, 6H), 3.83 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ
161.0, 158.7, 139.1, 137.2, 129.3, 128.8, 127.2, 118.5, 114.8, 104.6, 102.3, 100.2, 55.7, 55.4;
17

HRMS (ESI) m/z calcd for C20H23O4 [M + H]+ 327.1596, found 327.1681; RP-HPLC purity 97%
at 254 nm, tR = 23.97 min.
(E)-2-[4-(3,5-Dimethoxystyryl)-2,6-dimethoxyphenyl]ethanol (6).17 Compound 6 was obtained as
a white solid (0.33 g, 72% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.05 (d, J = 16.4 Hz, 1H), 6.99
(d, J = 16.0 Hz, 1H), 6.71 (s, 2H), 6.68 (d, J = 2.4 Hz, 2H), 6.40 (s, 1H), 3.88 (s, 6H), 3.84 (s,
6H), 3.77 (t, J = 6.0 Hz, 2H), 2.98 (t, J = 6.6 Hz, 2H), 1.83 (br, 1H); 13C NMR (CDCl3, 100
MHz)
δ 161.0, 158.6, 139.2, 136.8, 129.5, 128.5, 115.3, 104.5, 102.2, 100.1, 62.8, 55.8, 55.4,
26.6; HRMS (ESI) m/z calcd for C20H25O5 [M + H]+ 345.1702, found 345.1787; RP-HPLC
purity 98% at 254 nm, tR = 18.96 min.
General Procedure for HWE Olefination (9a). To a solution of aryl phosphonate (1.2 equiv) in
THF at 0 °C under Ar atmosphere, NaH (60% dispersion in mineral oil, 2.0 equiv) was slowly
added, and the reaction was stirred for 30 min. A solution of the corresponding benzaldehyde
(1.0 equiv) in THF was added dropwise and the resulting reaction mixture was stirred at rt for 12
h. The reaction was monitored by TLC. After completion of the reaction, the mixture was cooled
to 0 °C and excess NaH was quenched with water. The reaction mixture was poured on ice,
followed by the addition of 2.0 N HCl till pH 6 was obtained and the product was extracted with
EtOAc. The combined organic layers were washed with brine, dried over MgSO4, filtered, and
concentrated in vacuo. Purification by Flash Colum Chromatography (FCC) afforded the desired
(E)-stilbene.
(E)-1-Bromo-4-styrylbenzene (9a). Purification by FCC (silica gel, 0−5% EtOAc in hexanes)
1
afforded 9a as a white solid (0.54 g, 30% yield). H NMR (CDCl3, 400 MHz)
δ 7.51−7.46 (m,
4H), 7.37 (d, J = 8.8 Hz, 4H), 7.28 (d, J = 8.0 Hz, 1H), 7.09 (d, J = 16.0 Hz, 1H), 7.02 (d, J =
18

16.4 Hz, 1H); 13C NMR (CDCl3, 100 MHz)
δ 136.9, 136.2, 131.7, 129.4, 128.7, 127.9, 127.8,
127.4, 126.5, 121.3; RP-HPLC purity 96.0% at 254 nm, tR = 25.32 min.
General Procedure for Stille Coupling (10a,b). Tributyl(vinyl)tin (1.1 equiv), CsF (2.0
equiv), and Pd(t-Bu3P)2 (0.01 equiv) were added to a solution of corresponding (E)-
bromostilbene (1.0 equiv) in toluene and the resulting reaction mixture was refluxed for 12 h.
The reaction was monitored by TLC. The solution was cooled, filtered through a celite-silica pad
to remove a fine tan powder and thoroughly washed with diethyl ether. The obtained filtrate was
concentrated in vacuo to give a crude product. Purification by FCC afforded the corresponding
vinyl stilbene.
(E)-1-Styryl-4-vinylbenzene (10a). Purification by FCC (silica gel, 0−5% EtOAc in hexanes)
afforded 10a as a white solid (0.18 g, 97% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.51 (d, J = 7.2
Hz, 2H), 7.48 (d, J = 8.4 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.36 (t, J = 7.6 Hz, 2H), 7.26 (t, J =
7.2 Hz, 1H), 7.10 (s, 2H), 6.72 (dd, J = 17.6, 10.8 Hz, 1H), 5.76 (d, J = 17.6 Hz, 1H), 5.25 (d, J =
11.2 Hz, 1H); 13C NMR (CDCl3, 100 MHz)
δ 137.3, 136.9, 136.8, 136.4, 128.7, 128.6, 128.3,
127.6, 126.7, 126.54, 126.49, 113.7; HRMS (ESI) m/z calcd for C16H15 [M + H]+ 207.1174,
found 207.1185; RP-HPLC purity 96.9% at 254 nm, tR = 22.33 min.
(E)-1,3-Dimethoxy-5-(4-vinylstyryl)benzene (10b). Purification by FCC (silica gel, 0−4% EtOAc
in hexanes) afforded 10b as a white solid (0.27g, 65% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.48
(d, J = 8.0 Hz, 2H), 7.41 (d, J = 8.0 Hz, 2H), 7.08 (d, J = 16.4 Hz, 1H), 7.03 (d, J = 16.4 Hz, 1H),
6.72 (dd, J = 17.6, 10.8 Hz, 1H), 6.68 (d, J = 2.0 Hz, 2H), 6.40 (s, 1H), 5.77 (d, J = 17.6 Hz, 1H),
5.26 (d, J = 10.8 Hz, 1H), 3.84 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ 160.9, 139.3, 136.9,
136.6, 136.4, 128.7, 128.5, 126.7, 126.5, 113.8, 104.5, 100.0, 55.3; HRMS (ESI) m/z calcd for
19

C18H19O2 [M + H]+ 267.1385, found 267.1402; RP-HPLC purity 97.2% at 254 nm, tR = 5.54 min
(compound purity was assessed using a gradient of 80% CH3CN to 100% CH3CN in 35 min).
(E)-2-(4-Styrylphenyl)ethanol (11). A solution of compound 10a (50.0 mg, 0.24 mmol) in dry
THF (5.0 mL) was cooled to 0 °C, and 0.5 M 9-BBN-H in THF (2.5 mL, 1.2 mmol) was added.
The reaction mixture was kept in an ice bath for 30 min, and left at rt for 20 h. The reaction
progress was monitored by TLC. The reaction mixture was cooled to 0 °C, and MeOH (2.0 mL)
was added dropwise. When gas evolution had ceased, H2O (2.0 mL) was added, followed by a
mixture of 2.0 M NaOH (2.0 mL) and H2O2 (30% (w/w) in H2O, 1.06 mL, 9.30 mmol). The ice
bath was removed and the mixture was stirred vigorously at rt for 4 h. The mixture was filtered
to remove the precipitate and the filtrate was diluted with EtOAc (10.0 mL). The organic layer
was washed with brine, dried over MgSO4, filtered, and concentrated in vacuo. The resulting
residue was purified by FCC (silica gel, 0−50% EtOAc in hexanes), furnishing 11 as a white
solid (30.0 mg, 55% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.51 (d, J = 7.6 Hz, 2H), 7.47 (d, J =
8.0 Hz, 2H), 7.36 (t, J = 7.6, 2H), 7.24 (t, J = 7.2 Hz, 3H), 7.09 (s, 2H), 3.88 (t, J = 6.6 Hz, 2H),
2.88 (t, J = 6.6 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
δ
137.9, 137.3, 135.6, 129.3, 128.6, 128.3,
128.2, 127.5, 126.7, 126.4, 63.6, 38.9; HRMS (ESI) m/z calcd for C16H17O [M + H]+ 225.1279,
found 225.1268; RP-HPLC purity 95.2% at 254 nm, tR = 16.55 min.
Synthesis of Compounds 12a,b. The compounds were synthesized using synthetic procedure
similar to 9a.
(E)-1,2-Bis(3,5-dimethoxyphenyl)ethene (12a). Purification by FCC (silica gel, 0−5% EtOAc in
hexanes) afforded 12a as a white solid (20.0 mg, 62% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.01
13
(s, 2H), 6.67 (d, J = 2.4 Hz, 4H), 6.40 (t, J = 2.2 Hz, 2H), 3.83 (s, 12H); C NMR (CDCl3, 100
20

MHz)
δ
160.9, 139.0, 129.1, 104.5, 100.4, 55.3; HRMS (ESI) m/z calcd for C18H21O4 [M + H]+
301.1440, found 301.1443; RP-HPLC purity >99% at 254 nm, tR = 21.52 min.
(E)-5-(3,5-Dimethoxystyryl)-2-ethyl-1,3-dimethoxybenzene (12b). Purification by FCC (silica
1
gel, 0−10% EtOAc in hexanes) afforded 12b as a white solid (40.0 mg, 44% yield). H NMR
(CDCl3, 400 MHz)
δ 7.05 (d, J = 16.4 Hz, 1H), 6.98 (d, J = 16.0 Hz, 1H), 6.69 (s, 2H), 6.67 (d, J
= 2.4 Hz, 2H), 6.39 (t, J = 2.2 Hz, 1H), 3.87 (s, 6H), 3.83 (s, 6H), 2.66 (q, J = 7.5 Hz, 2H), 1.08
(t, J = 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz)
δ
160.9, 158.1, 139.3, 135.6, 129.6, 127.8,
121.0, 104.4, 102.1, 99.8, 55.7, 55.3, 16.4, 13.8; HRMS (ESI) m/z calcd for C20H25O4 [M + H]+
329.1753, found 329.1753; RP-HPLC purity >99% at 254 nm, tR = 25.22 min.
Synthesis of Compounds 16a−g. Compounds 16a−e and 16g were synthesized using
synthetic procedure similar to 10a,b.
(E)-5-(4-Fluorostyryl)-1,3-dimethoxy-2-vinylbenzene (16a). Purification by FCC (silica gel,
1
0−4% EtOAc in hexanes) afforded 16a as a white solid (0.19 g, 94% yield). H NMR (CDCl3,
400 MHz)
δ 7.48 (dd, J = 8.4, 5.6 Hz, 2H), 7.07 (d, J = 8.8 Hz, 2H), 6.94 (m, 3H merged), 6.69
(s, 2H), 6.10 (dd, J = 18.0, 2.8 Hz, 1H), 5.44 (dd, J = 12.8, 2.4 Hz, 1H), 3.90 (s, 6H); 13C NMR
(CDCl3, 100 MHz)
δ 163.1, 161.1, 158.7, 137.1, 133.29, 133.26, 128.57, 128.54, 128.0, 127.9,
127.6, 127.1, 118.4, 115.7, 115.5, 114.6, 102.1, 55.7; HRMS (ESI) m/z calcd for C18H18FO2 [M
+ H]+ 285.1290, found 285.1303; RP-HPLC purity 97.3% at 254 nm, tR = 24.86 min.
(E)-1,3-Dimethoxy-5-(4-(methoxymethoxy)styryl)-2-vinylbenzene (16b). Purification by FCC
(silica gel, 0−5% EtOAc in hexanes) afforded 16b as a light yellow solid (0.38 g, 79% yield). 1H
NMR (CDCl3, 400 MHz)
δ
7.45 (d, J = 8.8 Hz, 2H), 7.07−7.01 (m, 3H), 6.96 (s, 1H), 6.95 (dd, J
21

= 17.2, 10.0 Hz, 1H), 6.69 (s, 2H), 6.09 (dd, J = 18.0, 2.8 Hz, 1H), 5.43 (dd, J = 12.4, 2.8 Hz,
1H), 5.19 (s, 2H), 3.90 (s, 6H), 3.49 (s, 3H); 13C NMR (CDCl3, 100 MHz)
δ
158.7, 156.9, 137.6,
131.0, 128.2, 127.7, 127.2, 127.1, 118.2, 116.4, 114.3, 102.0, 94.4, 56.0, 55.7; HRMS (ESI) m/z
calcd for C20H23O4 [M + H]+ 327.1596, found 327.1605; RP-HPLC purity >99% at 254 nm, tR =
23.4 min.
(E)-1,3-Dimethoxy-5-(4-(trifluoromethyl)styryl)-2-vinylbenzene (16c). Purification by FCC
(silica gel, 0−3% EtOAc in hexanes) afforded 16c as a white solid (0.77 g, 83% yield). 1H NMR
(CDCl3, 400 MHz)
δ 7.61 (s, 4H), 7.15 (d, J = 16.4 Hz, 1H), 7.09 (d, J = 16.4 Hz, 1H), 6.98 (dd,
J = 18.0, 12.4 Hz, 1H), 6.73 (s, 2H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.0, 2.8 Hz,
1H), 3.91 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ
158.7, 140.6, 136.6, 131.3, 129.5, 129.1,
127.2, 127.1, 126.6, 125.7−125.5, 118.8, 115.3, 102.5, 55.8; HRMS (ESI) m/z calcd for
C19H18F3O2 [M + H]+ 335.1259, found 335.1243; RP-HPLC purity 98.4% at 254 nm, tR = 26.62
min.
(E)-1,3-Dimethoxy-5-(2-(trifluoromethyl)styryl)-2-vinylbenzene (16d). Purification by FCC
1
(silica gel, 0−5% EtOAc in hexanes) afforded 16d as a white solid (33.0 mg, 38% yield). H
NMR (CDCl3, 400 MHz)
δ 7.78 (d, J = 8.0 Hz, 1H), 7.67 (d, J = 7.6 Hz, 1H), 7.54 (t, J = 7.6 Hz,
1H), 7.44 (d, J = 16.0 Hz, 1H), 7.36 (t, J = 7.6 Hz, 1H), 7.03 (d, J = 15.6 Hz, 1H), 6.98 (dd, J =
18.0, 12.0 Hz, 1H), 6.71 (s, 2H), 6.11 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.0, 2.8 Hz, 1H),
3.91 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ 158.7, 136.8, 136.2, 132.7, 131.8, 127.2, 127.1,
126.9, 126.0, 125.99, 125.93, 125.79, 124.5, 123.0, 118.7, 115.3, 102.6, 55.77, 55.74; HRMS
(ESI) m/z calcd for C19H18F3O2 [M + H]+ 335.1259, found 335.1255; RP-HPLC purity 98.3% at
254 nm, tR = 26.33 min.
22

(E)-1,3-Dimethoxy-5-(3-(trifluoromethyl)styryl)-2-vinylbenzene (16e). Purification by FCC
(silica gel, 0−5% EtOAc in hexanes) afforded 16e as a light yellow solid (32.0 mg, 37% yield).
1H NMR (CDCl3, 400 MHz)
δ 7.76 (s, 1H), 7.68 (d, J = 7.6 Hz, 1H), 7.52−7.45 (m, 2H merged),
7.14 (d, J = 16.8 Hz, 1H), 7.10 (d, J = 16.8 Hz, 1H), 6.98 (dd, J = 18.0, 12.4 Hz, 1H), 6.72 (s,
2H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.2, 2.6 Hz, 1H), 3.91 (s, 6H); 13C NMR
(CDCl3, 100 MHz)
δ 158.7, 137.9, 136.6, 131.3, 130.9, 130.6, 129.5, 129.1, 127.17, 127.10,
124.13, 124.09, 123.0, 118.7, 115.1, 102.4, 55.78, 55.75; HRMS (ESI) m/z calcd for C19H18F3O2
[M + H]+ 335.1259, found 335.1252; RP-HPLC purity 98.5% at 254 nm, tR = 26.47 min.
(E)-Methyl 4-(3,5-dimethoxy-4-vinylstyryl)benzoate (16g). Purification by FCC (silica gel, 0−4%
EtOAc in hexanes) afforded 16g as a light green solid (0.70 g, 95% yield). 1H NMR (CDCl3, 400
MHz)
δ 8.03 (d, J = 8.0 Hz, 2H), 7.58 (d, J = 8.4 Hz, 2H), 7.19 (d, J = 16.0 Hz, 1H), 7.12 (d, J =
16.4 Hz, 1H), 6.99 (dd, J = 18.0, 12.0 Hz, 1H), 6.73 (s, 2H), 6.12 (dd, J = 18.0, 2.4 Hz, 1H), 5.47
(dd, J = 12.0, 2.8 Hz, 1H), 3.93 (s, 3H), 3.92 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ
166.8,
158.7, 141.6, 136.7, 131.3, 130.0, 128.9, 127.6, 127.1, 126.3, 118.7, 115.2, 102.5, 55.7, 52.0;
HRMS (ESI) m/z calcd for C20H21O4 [M + H]+ 325.1440, found 325.1448; RP-HPLC purity
98.7% at 254 nm, tR = 24.38 min.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)benzoic acid (16f). Lithium hydroxide monohydrate (5.0
equiv) was added to a suspension of 16g (1.0 equiv) in THF:H2O:MeOH (1:1:1), and stirred at
room temperature. Reaction mass was evaporated to dryness, residue was re-dissolved in water.
The aqueous layer was washed with hexane, acidified with 2.0 M HCl and the precipitated solid
was filtered and dried to obtain 16f as a light green solid (0.15 g, 93% yield). 1H NMR (DMSO-
d6, 400 MHz) δ 12.88 (br, 1H), 7.95 (d, J = 8.4 Hz, 2H), 7.72 (d, J = 8.8 Hz, 2H), 7.44 (d, J =
23

16.4 Hz, 1H), 7.38 (d, J = 16.4 Hz, 1H), 6.97 (s, 2H), 6.88 (dd, J = 18.0, 12.0 Hz, 1H), 6.05 (dd,
13
J = 18.0, 2.8 Hz, 1H), 5.36 (dd, J = 12.4, 2.8 Hz, 1H), 3.87 (s, 6H); C NMR (DMSO-d6, 100
MHz) δ 167.4, 158.7, 141.8, 137.5, 131.5, 130.2, 129.9, 128.3, 127.5, 126.9, 118.7, 114.1, 103.2,
56.2; HRMS (ESI) m/z calcd for C19H19O4 [M + H]+ 311.1283, found 311.1280; RP-HPLC
purity 96.7% at 254 nm, tR = 19.41 min.
General Procedure for the Synthesis of 17a−d. To a solution of corresponding carboxylic
acid (1.0 equiv) in DMF at 0 °C under argon atmosphere, K2CO3 (2.0 equiv) was added, and the
resulting mixture was stirred for 20 min. The corresponding benzyl or propargyl halide (1.1
equiv) was added and reaction mixture was stirred at rt for 12 h. The reaction mixture was
quenched with water and extracted with EtOAc. The combined organic layers were washed with
brine, dried over MgSO4, filtered, and concentrated in vacuo. Purification by FCC afforded the
desired ester.
(E)-Prop-2-yn-1-yl 4-(3,5-dimethoxy-4-vinylstyryl)benzoate (17a). Purification by FCC (silica
gel, 0−10% EtOAc in hexanes) afforded 17a as a light green solid (0.11 g, 74% yield). 1H NMR
(CDCl3, 400 MHz)
δ 8.06 (d, J = 8.4 Hz, 2H), 7.59 (d, J = 8.4 Hz, 2H), 7.19 (d, J = 16.4 Hz,
1H), 7.12 (d, J = 16.4 Hz, 1H), 6.98 (dd, J = 18.0, 12.4 Hz, 1H), 6.73 (s, 2H), 6.12 (dd, J = 18.0,
2.8 Hz, 1H), 5.46 (dd, J = 12.0, 2.8 Hz, 1H), 4.94 (d, J = 2.4 Hz, 2H), 3.91 (s, 6H), 2.53 (t, J =
3.2 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 165.5, 158.7, 142.0, 136.6, 131.5, 130.3, 128.1,
127.5, 127.1, 126.3, 118.8, 115.2, 102.5, 77.7, 75.0, 55.7, 52.4; HRMS (ESI) m/z calcd for
C22H21O4 [M + H]+ 349.1440, found 349.1432; RP-HPLC purity 97.1% at 254 nm, tR = 24.61
min.
24

(E)-Benzyl 4-(3,5-dimethoxy-4-vinylstyryl)benzoate (17b). Purification by FCC (silica gel,
1
0−10% EtOAc in hexanes) afforded 17b as a white solid (35.0 mg, 68% yield). H NMR
(CDCl3, 400 MHz)
δ 8.07 (d, J = 8.4 Hz, 2H), 7.57 (d, J = 8.4 Hz, 2H), 7.47−7.34 (m, 5H), 7.18
(d, J = 16.0 Hz, 1H), 7.11 (d, J = 16.0 Hz, 1H), 6.98 (dd, J = 17.8, 12.2 Hz, 1H), 6.73 (s, 2H),
13
6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.2, 2.6 Hz, 1H), 5.37 (s, 2H), 3.91 (s, 6H); C
NMR (CDCl3, 100 MHz) δ 166.1, 158.7, 141.7, 136.6, 136.0, 131.3, 130.1, 128.8, 128.6, 128.3,
128.2, 127.6, 127.1, 126.3, 118.8, 115.1, 102.4, 66.7, 55.7; HRMS (ESI) m/z calcd for C26H25O4
[M + H]+ 401.1753, found 401.1751; RP-HPLC purity >99% at 254 nm, tR = 28.01 min.
(E)-4-Fluorobenzyl 4-(3,5-dimethoxy-4-vinylstyryl)benzoate (17c). Purification by FCC (silica
1
gel, 0−5% EtOAc in hexanes) afforded 17c as a yellow solid (26.0 mg, 43% yield). H NMR
(CDCl3, 400 MHz)
δ 8.04 (d, J = 8.4 Hz, 2H), 7.57 (d, J = 8.4 Hz, 2H), 7.45−7.42 (m, 2H), 7.17
(d, J = 16.4 Hz, 1H), 7.10 (d, J = 16.4 Hz, 1H), 7.09−7.05 (m, 2H), 6.98 (d, J = 18.0, 12.0 Hz,
1H), 6.72 (s, 2H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.2, 2.6 Hz, 1H), 5.32 (s, 2H),
3.90 (s, 6H); 13C NMR (CDCl3, 100 MHz) δ 166.1, 158.7, 141.8, 136.6, 131.9, 131.4, 130.3,
130.2, 128.7, 127.5, 127.1, 126.3, 118.8, 115.6, 115.4, 115.2, 102.5, 65.9, 55.7; HRMS (ESI) m/z
calcd for C26H24FO4 [M + H]+ 419.1659, found 419.1673; RP-HPLC purity 96.7% at 254 nm, tR
= 28.23 min.
(E)-4-(Trifluoromethyl)benzyl 4-(3,5-dimethoxy-4-vinylstyryl)benzoate (17d). Purification by
FCC (silica gel, 0−5% EtOAc in hexanes) afforded 17d as a yellow solid (22.0 mg, 33% yield).
1H NMR (CDCl3, 400 MHz)
δ 8.07 (d, J = 8.4 Hz, 2H), 7.66 (d, J = 8.0 Hz, 2H), 7.60−7.56 (m,
4H), 7.19 (d, J = 16.4 Hz, 1H), 7.12 (d, J = 16.4 Hz, 1H), 6.98 (dd, J = 17.8, 12.2 Hz, 1H), 6.73
(s, 2H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.48 (dd, J = 12.2, 2.6 Hz, 1H), 5.42 (s, 2H), 3.92 (s,
25

6H); 13C NMR (CDCl3, 100 MHz) δ 165.9, 158.7, 142.0, 140.0, 136.6, 131.6, 130.2, 128.4,
128.1, 127.5, 127.1, 126.4, 125.6, 125.5, 118.8, 115.3, 102.5, 65.7, 55.7; HRMS (ESI) m/z calcd
for C19H18O3 [M – (CF3PhO)]+ 293.1178, found 293.1184; RP-HPLC purity 96.8% at 254 nm, tR
= 29.13 min.
General Procedure for Amide Coupling (18a−m). EDCI (1.2 equiv) and HOBt (1.2 equiv) or
HATU (1.2 equiv) were added to a solution of appropriate acid (1.0 equiv), corresponding amine
(1.0 equiv), and DIPEA (2.5 equiv) in DMF, and the reaction mixture was stirred at room
temperature until complete consumption of the starting material. The reaction was monitored by
TLC. The reaction mixture was quenched with water and extracted with EtOAc. The combined
organic layer was washed with brine, dried over anhydrous MgSO4, and concentrated in vacuo.
The resulting residue was purified by FCC.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)-N-(furan-2-ylmethyl)benzamide (18a). EDCI and HOBt
were used as coupling reagents. Purification by FCC (silica gel, 0−30% EtOAc in hexanes)
1
afforded 18a as a white solid (28.0 mg, 45% yield). H NMR (CDCl3, 400 MHz)
δ 7.78 (d, J =
8.4 Hz, 2H), 7.56 (d, J = 8.0 Hz, 2H), 7.39 (s, 1H), 7.14 (d, J = 16.0 Hz, 1H), 7.09 (d, J = 16.4
Hz, 1H), 6.98 (dd, J = 18.0, 12.0 Hz, 1H), 6.72 (s, 2H), 6.43 (t, J = 5.4 Hz, 1H), 6.35 (s, 1H),
6.31 (s, 1H), 6.11 (dd, J = 18.0, 2.4 Hz, 1H), 5.45 (dd, J = 12.4, 2.4 Hz, 1H), 4.66 (d, J = 5.6 Hz,
2H), 3.90 (s, 6H); 13C NMR (CDCl3, 100 MHz)
δ 166.7, 158.7, 151.1, 142.3, 140.4, 136.8,
132.9, 130.9, 127.6, 127.5, 127.1, 126.5, 118.7, 115.2, 110.5, 107.7, 102.5, 55.8, 37.0; HRMS
(ESI) m/z calcd for C24H24NO4 [M + H]+ 390.1705, found 390.1709; RP-HPLC purity 96.0% at
254 nm, tR = 20.44 min.
26

(E)-N-Allyl-4-(3,5-Dimethoxy-4-vinylstyryl)benzamide (18b). EDCI and HOBt were used as
coupling reagents. Purification by FCC (silica gel, 0−5% MeOH in DCM) afforded 18b as a
yellow solid (15.0 mg, 27% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.79 (d, J = 8.4 Hz, 2H), 7.57
(d, J = 8.4 Hz, 2H), 7.15 (d, J = 16.0 Hz, 1H), 7.10 (d, J = 16.4 Hz, 1H), 6.98 (dd, J = 18.0, 12.4
Hz, 1H), 6.73 (s, 2H), 6.20 (t, J = 5.4 Hz, 1H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 6.00−5.90 (m,
1H), 5.46 (dd, J = 12.2, 2.6 Hz, 1H), 5.29 (dd, J = 17.0, 1.0 Hz, 1H), 5.21 (dd, J = 10.2, 1.0 Hz,
13
1H), 4.12 (t, J = 5.6 Hz, 2H), 3.91 (s, 6H); C NMR (CDCl3, 100 MHz)
δ 166.8, 158.7, 140.3,
136.7, 134.1, 133.1, 130.7, 127.5, 127.4, 127.1, 126.5, 118.7, 116.8, 115.0, 102.4, 55.7, 42.4;
HRMS (ESI) m/z calcd for C22H24NO3 [M + H]+ 350.1756, found 350.1746; RP-HPLC purity
95.8% at 254 nm, tR = 19.93 min.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)-N-(4-(trifluoromethyl)phenyl)benzamide (18c). EDCI and
HOBt were used as coupling reagents. Purification by FCC (silica gel, 0−20% EtOAc in
hexanes) afforded 18c as a white solid (33.0 mg, 66% yield). 1H NMR (CDCl3, 400 MHz)
δ 7.93
(d, J = 8.0 Hz, 2H), 7.85 (d, J = 8.4 Hz, 2H), 7.64 (s, J = 7.4 Hz, 4H), 7.20 (d, J = 16.4 Hz, 1H),
7.14 (d, J = 16.8 Hz, 1H), 6.98 (dd, J = 17.8, 12.2 Hz, 1H), 6.75 (s, 2H), 6.12 (dd, J = 18.0, 2.4
Hz, 1H), 5.46 (dd, J = 12.2, 2.8 Hz, 1H), 3.92 (s, 6H), 3.38 (br, 1H); 13C NMR (CDCl3, 100
MHz)
δ 166.3, 158.8, 141.0, 136.8, 133.2, 131.2, 128.0, 127.5, 127.2, 126.7, 126.2, 120.1, 118.8,
115.3, 102.6, 55.8; HRMS (ESI) m/z calcd for C26H23F3NO3 [M + H]+ 454.1630, found
454.1631; RP-HPLC purity 95.3% at 254 nm, tR = 26.98 min.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)-N-phenethylbenzamide (18d). EDCI and HOBt were used as
coupling reagents. Purification by FCC (silica gel, 0−30% EtOAc in hexanes) afforded 18d as a
1
white solid (35.0 mg, 53% yield). H NMR (CDCl3, 400 MHz)
δ
7.69 (d, J = 8.4 Hz, 2H), 7.54
27

(d, J = 8.8 Hz, 2H), 7.33 (d, J = 7.2 Hz, 2H), 7.26 (t, J = 6.2 Hz, 3H), 7.13 (d, J = 16.4 Hz, 1H),
7.08 (d, J = 16.0 Hz, 1H), 6.98 (dd, J = 18.0, 12.4 Hz, 1H), 6.71 (s, 2H), 6.11 (dd, J = 17.8, 2.6
Hz, 1H), 5.45 (dd, J = 12.2 Hz, 2.6 Hz, 1H), 3.90 (s, 6H), 3.74 (q, J = 6.5 Hz, 2H), 2.95 (t, J =
6.8 Hz, 2H); 13C NMR (CDCl3, 100 MHz)
δ 166.9, 158.7, 140.2, 138.9, 136.7, 133.3, 130.7,
128.8, 128.7, 127.6, 127.3, 127.1, 126.6, 126.5, 118.7, 115.1, 102.4, 55.7, 41.1, 35.7; HRMS
(ESI) m/z calcd for C27H28NO3 [M + H]+ 414.2069, found 414.2069; RP-HPLC purity 98.4% at
254 nm, tR = 22.45 min.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)-N-(2-(pyridin-4-yl)ethyl)benzamide (18e). EDCI and HOBt
were used as coupling reagents. Purification by FCC (silica gel, 0−100% EtOAc in hexanes)
1
afforded 18e as a white solid (26.0 mg, 39% yield). H NMR (CDCl3, 400 MHz)
δ 8.54 (d, J =
5.6 Hz, 2H), 7.70 (d, J = 8.0 Hz, 2H), 7.56 (d, J = 8.4 Hz, 2H), 7.18 (d, J = 5.6 Hz, 2H), 7.15 (d,
J = 16.4 Hz, 1H), 7.09 (d, J = 16.4 Hz, 1H), 6.98 (dd, J = 18.0, 12.0 Hz, 1H), 6.72 (s, 2H), 6.24
(t, J = 5.6 Hz, 1H), 6.12 (dd, J = 18.0, 2.8 Hz, 1H), 5.46 (dd, J = 12.2, 2.6 Hz, 1H), 3.91 (s, 6H),
13
3.75 (q, J = 6.7 Hz, 2H), 2.97 (t, J = 7.0 Hz, 2H); C NMR (CDCl3, 100 MHz)
δ 167.1, 158.7,
150.0, 148.0, 140.7, 136.7, 132.9, 130.9, 127.4, 127.3, 127.1, 126.6, 124.2, 118.7, 115.1, 102.4,
55.7, 40.3, 35.1; HRMS (ESI) m/z calcd for C26H27N2O3 [M + H]+ 415.2022, found 415.2024;
RP-HPLC purity 96.8% at 254 nm, tR = 9.68 min.
(E)-4-(3,5-Dimethoxy-4-vinylstyryl)-N-(2-(pyridin-2-yl)ethyl)benzamide (18f). EDCI and HOBt
were used as coupling reagents. Purification by FCC (silica gel, 0−5% MeOH in DCM) afforded
1
18f as a light brown solid (12.0 mg, 53% yield). H NMR (CDCl3, 400 MHz)
δ 8.58 (d, J = 4.8
Hz, 1H), 7.79 (d, J = 8.4 Hz, 2H), 7.67−7.63 (m, 1H), 7.57 (d, J = 8.4 Hz, 3H), 7.23 (d, J = 8.0
Hz, 1H), 7.20−7.17 (m, 1H), 7.15 (d, J = 16.4 Hz, 1H), 7.10 (d, J = 16.0 Hz, 1H), 6.98 (dd, J =
28