Molecular iodine-mediated reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts: An easy route to naphthyl ketones and iodo-substituted isochromenes

Article abstract of DOI:10.1039/c4ob00938j

The molecular iodine-promoted reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts is reported. In the presence of I₂, naphthyl ketone derivatives are produced, whereas in the presence of I₂/K₃PO₄, iodo-substituted isochromene derivatives are produced. This journal is

Full text of DOI:10.1039/c4ob00938j

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Molecular iodine-mediated reaction of 2-(2-
phenylethynyl)-Morita–Baylis–Hillman adducts:
an easy route to naphthyl ketones and
iodo-substituted isochromenes†
Cite this: Org. Biomol. Chem., 2014,
12, 8247
Donala Janreddy, Veerababurao Kavala, Trimurtulu Kotipalli, R. R. Rajawinslin,
Chun-Wei Kuo, Wen-Chang Huang and Ching-Fa Yao*
Received 7th May 2014,
Accepted 13th August 2014
The molecular iodine-promoted reaction of 2-(2-phenylethynyl)-Morita–Baylis–Hillman adducts is
reported. In the presence of I2, naphthyl ketone derivatives are produced, whereas in the presence of
I2/K3PO4, iodo-substituted isochromene derivatives are produced.
DOI: 10.1039/c4ob00938j
www.rsc.org/obc
Introduction
The development of aromatic compounds and new methods
for their construction has been of great interest, due to the fact
that such moieties are present in various drugs and in devices
used in the field of materials science.1 Among such aromatic
compounds, naphthalene derivatives have enjoyed widespread
use in the field of chiral catalysts, biologically active com-
pounds, synthetic intermediates and advanced functional
materials.2 Hence, the development of new and efficient
methods for the synthesis of polysubstituted naphthalene
derivatives is of great importance. Traditional methods used in
the construction of naphthalene derivatives involve electro-
philic substitution or coupling reactions, in conjunction with
multistep procedures.3 However, over the past several years,
the Lewis acid-catalyzed benzannulation of o-alkynyl-substi-
tuted carbonyl compounds with alkynes, alkenes, and enols
has proved to be one of the most powerful and reliable
approaches for the construction of naphthalene derivatives.4,5
In contrast, the electrophilic cyclization of alkynes has been
extensively explored by Barluenga, Larock and others. Among
the various electrophiles, the iodine-activated cyclization of
ortho substituted aryl alkynes is one of the more interesting
techniques for the construction of iodine containing fused
heterocyclic derivatives.6 Nachtsheim et al. recently reported
on the synthesis of 1-naphthalenone derivatives by the iodocy-
Fig. 1 Previous and present reports on the synthesis of naphthalenes
from Morita–Baylis–Hillman adducts.
clization reaction of o-alkynylphenyl carboxaldehyde with sty-
renes in the presence of tetrabutylammonium iodide (TBAI),
oxone and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as
a
solvent.7 Kim et al. reported on the synthesis of naphthalene
derivatives from Morita–Baylis–Hillman (MBH) adducts using
a copper catalyst (Fig. 1).8 However, to the best of our knowl-
edge, the synthesis of naphthyl ketone derivatives starting
from
2-(2-phenylethynyl)-Morita–Baylis–Hillman
adducts
using molecular iodine has not been reported in the literature.
In fact, in recent years, we reported on some iodine-mediated
reactions for the synthesis of a variety of heterocyclic com-
pounds.9 In continuation of these studies, we wish to report
herein on the molecular iodine mediated cyclization reaction
of 2-(2-phenylethynyl)-MBH adducts to give naphthyl ketones
and iodo-substituted 1H-isochromene derivatives.
Department of Chemistry, National Taiwan Normal University, 88, Sec. 4, Ting-chow
Road, Taipei, Taiwan 116, Republic of China. E-mail: cheyaocf@ntnu.edu.tw,
cheyaocf@yahoo.com.tw
†Electronic supplementary information (ESI) available: Detailed experimental
procedures and the 1H and 13C NMR spectra for relevant compounds. CCDC
972525, 978566, 973915 and 1009697. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c4ob00938j
Results and discussion
To achieve our goal, compound 1a was treated with molecular
iodine (3.0 equiv.) in acetonitrile at 50 °C for 3 h. Under these
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conditions, three products were produced. From 1H and
13C NMR spectral analyses, the major product was determined
to be methyl 2-(acetamidomethyl)-3-(2-(phenylethynyl)phenyl)-
acrylate (1c), which was further confirmed by single crystal
X-ray analysis (ESI†). Spectral data for the minor product
suggested that it was methyl 4-benzoyl-2-naphthoate (1b) and
the structure was further confirmed by a single crystal X-ray
analysis (Fig. 2). Another minor product was methyl 2-(iodo-
methyl)-3-(2-(phenylethynyl)phenyl)acrylate (1d). The structure
of compound 1d was confirmed by a single crystal X-ray ana-
lysis (ESI†). The formation of 1c might have occurred through
a Ritter reaction. From these experimental results, it is quite
clear that acetonitrile functions both as a nucleophile and a
solvent in the present reaction to provide the methyl 2-(acet-
amidomethyl)-3-(2-(phenylethynyl)phenyl)acrylate derivative
(1c). Hence, the same reaction was conducted in dichloro-
methane as the solvent. In this case, the reaction furnished
methyl 4-benzoyl-2-naphthoate (1b) in 50% isolated yield.
Encouraged by these results, we further screened a variety of
Table 1 Optimization studies for producing naphthyl ketone derivatives
from a 2-(2-phenylethynyl)-Morita–Baylis–Hillman adduct
Isolated yield(s)b
(%)
Iodine
source
(3 equiv.)
Temp.
(°C)
Time
(h)
Entrya
Solvent
1b
1c
1d
1
CH3CN
DCM
DCM
Toluene
THF
DCE
DMF
I2
I2
I2
I2
I2
I2
I2
NIS
ICl
50
50
50
50
50
50
50
50
50
3
4
5
4
4
4
12
3
20
50
30
—
—
40
Trace
20
20
50
—
—
—
—
—
—
—
—
10
20
35
50
45
25
—
—
—
2
2c
3
4
5
6
7d
8
DCM
DCM
3
other solvents, including toluene, tetrahydrofuran (THF), a All reactions were conducted on a 1 mmol scale. b Isolated yields.
c 1.5 equiv. of iodine was used. d A mixture of iodo-substituted
N,N-dimethylformamide (DMF), and 1,2-dichloroethane
(DCE). To our disappointment, using toluene or THF as a
isochromene and dihydroisobenzofuran derivatives was produced.
solvent resulted in the production of the iodosubstituted
product 1d as a sole product (entries 3 and 4) and no trace of
reactions with the 2-(2-phenylethynyl)-MBH substrates 1a and
2a derived from methyl acrylate (Table 2, entries 1 and 2). In
the case of compound 1a (entry 1), the desired product 1b was
obtained in 50% isolated yield. Under the optimized reaction
conditions, the dioxole substituted substrate 2a (entry 2) pro-
duced the corresponding naphthyl ketone derivatives in mod-
erate yield. A similar trend was observed in the case of
reactions with MBH-compounds 3a and 4a derived from
methyl vinyl ketone, in which the expected products were
obtained in 55% and 51% yields, respectively (Table 2, entries
3 and 4). The scope of the methodology was further evaluated
by examining the production of substrates 5a and 6a, ethyl
acrylate and 2-cyclohexenone MBH adducts under the optimal
conditions. The corresponding naphthyl ketone derivatives
were produced in moderate-to-good yields (Table 2, entries
5 and 6). Consequently, when we examined the reaction with
compound 7a, the expected naphthyl ketone derivative was
obtained in good yield (entry 7). To introduce more variation
into our protocol, we used the 4-nitro and quinoline substi-
tuted compounds 8a and 9a as substrates under the present
reaction conditions. These substrates underwent iodocycliza-
tion instead of naphthyl ketone derivative formation, with
iodo-substituted isochromene derivatives being produced in
70% and 75% yields, respectively (entries 8 and 9).
the desired product was observed. When DCE was used as the
solvent, the expected product 1b was obtained in 40% isolated
yield (entry 5) and trace amounts of the desired product were
observed when DMF was used as the solvent (entry 6). From
the results, it is quite clear that DCM is the optimal solvent for
this transformation. We screened some additional iodine
reagents, such as NIS and ICl (entries 7 and 8), for the reac-
tion. Among the tested iodine sources, molecular iodine
proved to be the best choice. Thus, the optimum conditions
for the reaction include molecular iodine (3 equiv.) in DCM at
a temperature of 50 °C (Table 1).
With the optimized reaction conditions for the formation
of naphthyl ketone derivative in hand, we next explored the
scope and limitations of the methodology. In this regard, we
investigated the reaction using a variety of 2-(2-phenylethynyl)-
MBH adducts under the optimal reaction conditions and the
results are summarized in Table 2. We initially examined the
On the other hand, during our attempts to optimize the
reaction conditions for increasing the yield of naphthyl ketone
derivative 1b, we conducted the reaction with 1a in the pres-
ence of molecular iodine (3.0 equiv.) and K3PO4 as a base
(3.0 equiv.) in acetonitrile as the solvent at 50 °C. Under these
conditions, the reaction produced the iodo-substituted iso-
chromene derivative 1e as the sole product in 75% yield and
1
the structure was confirmed by H NMR, 13C NMR, LRMS and
Fig. 2 ORTEP diagram of the single-crystal X-ray structure of 1b.12
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been reported previously. This fact prompted us to further
investigate this reaction in more detail.
Table 2 Formation of naphthyl ketone derivatives via the iodine-
mediated reaction of 2-(2-phenylethynyl)-Morita–Baylis–Hillman
adducts
To determine the optimum conditions for this reaction, we
evaluated various iodine reagents, bases and solvents. We first
examined the use of various iodine reagents such as, I2, NIS,
and ICl (Table 3, entries 1–3). The reaction with NIS produces
the desired iodo-substituted isochromene along with iodo-sub-
stituted dihydroisobenzofuran. However, in the presence of
ICl, the reaction was incomplete and furnished a trace amount
of the iodo-substituted isochromene derivative after 24 h. We
further examined the reaction with a series of bases including
K3PO4, Et3N, K2CO3, and NaHCO3 (entries 1, 4, 5, and 6).
Among the bases tested, K3PO4 gave the best yield of the
desired product. We next investigated the effect of the solvent
on the reaction by carrying out the reactions in different sol-
vents such as CH3CN, CH2Cl2, CHCl3, DMSO and toluene
(entries 7–10). Solvents other than CH3CN produced a mixture
of iodo-substituted isochromene and dihydroisobenzofuran
derivatives under the present reaction conditions. Hence, the
best result was obtained when the reaction was performed in
the presence of I2 (3.0 equiv.) and K3PO4 (3.0 equiv.) in aceto-
nitrile as the solvent at 50 °C.
Time
(h)
Yieldb,c
(%)
Entrya
1
Substrate
Product
3
3
3
4
50
52
55
51
2
3
4
With these optimized conditions in hand, the scope of the
present protocol was investigated (Table 4). As shown in
Table 4, electron-neutral, electron-deficient and electron-rich
groups on 2-(2-phenylethynyl)-MBH adducts were all well toler-
ated and the desired products were obtained in moderate-to-
good yields (Table 4). The regioselectivity of the reaction
depends on the substitution pattern of the substrate.
5
6
7
2
2
6
70
50
60
The presence of an electron-withdrawing group in the
phenyl ring of the 2-(2-phenylethynyl)-MBH adduct 8a led to a
Table 3 Optimization conditions for iodo-substituted isochromene
derivative 1e
8
9
12
12
70
75
Product(s)b
Yield(s) (%)
Time
Entrya Electrophile Base
Solvent
(h)
1e
1f
1
2
3
4
I2 (3.0)
NIS (3.0)
ICl (3.0)
I2 (3.0)
I2 (3.0)
I2 (3.0)
I2 (3.0)
I2 (3.0)
I2 (3.0)
I2 (3.0.)
K3PO4 (3.0)
K3PO4 (3.0)
K3PO4 (3.0)
NaHCO3 (3.0) CH3CN
K2CO3 (3.0)
Et3N (3.0)
K3PO4 (3.0)
K3PO4 (3.0)
K3PO4 (3.0)
K3PO4 (3.0)
CH3CN
CH3CN
CH3CN
8
12
24
12
24
24
24
24
75
45
10
60
40
—
50
30
35
30
—
40
—
35
30
—
30
—
25
20
a All reactions were conducted on a 1 mmol scale. b Isolated yields.
c From entries 1–7, about 10–20% of 1d type 2-(iodomethyl) derivatives
were observed as side reaction products.
5c
6c
7c
8d
9c
10c
CH3CN
CH3CN
CHCl3
CH2Cl2
Toluene 24
DMSO 24
HRMS (Table 3, entry 1). In fact, the use of various iodine
reagents in the synthesis of iodo substituted 1H-isochromene
derivatives has been reported in the literature; to our knowl-
edge, the use of 2-(2-phenylethynyl)-MBH adducts in the syn-
thesis of iodo-substituted isochromene derivatives has not
a Unless otherwise noted, all the reactions were carried out on a
1
mmol scale. b NMR yields (CH2Br2 as an internal standard).
c Unreacted starting material was recovered. d 20% of compound 1b
was observed.
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mixture of isochromene and dihydrobenzofuran derivatives a mixture of the iodo-substituted isochromene and dihydro-
(Table 4, entry 4) (Fig. 3). Moreover, when an electron-donating isobenzofuran derivatives in good yields (entries 6 and 8).
group was present in the phenyl ring of 2-(2-phenylethynyl)- Finally, we conducted the reaction with the ethyl acrylate
MBH adducts, such as 10a and 2a, the isochromene derivative derivative of the 2-(2-phenylethynyl)-MBH adduct 5a under
was preferentially formed (Table 4, entries 2 and 7). Further- standard reaction conditions. An inseparable mixture of iodo-
more, reactions with compounds 3a and 6a derived from substituted isochromene and dihydrobenzofuran derivatives
methyl vinyl ketone and cyclohexenone, respectively, produced was produced in 80% isolated yield (entry 9).
Table 4 Synthesis of various iodo-substituted isochromene and dihydroisobenzofuran derivatives from 2-(2-phenylethynyl)-Morita–Baylis–Hillman
adducts
Entrya
1
Substrate
Temp. (°C)
50
Time (h)
8
Product(s)
Yield(s)b (%) (e) or (e, f)
62
2
3
rt
rt
5
58
65
24
4
rt
24
(40, 30)
5
6
rt
rt
24
3
70
(30, 35)
7
8
rt
24
24
60
40
(60, 15)
9
40
24
80c
a Unless otherwise noted, all the reactions were carried out on a 1.0 mmol scale. b Isolated yield. c An inseparable mixture of the two regioisomers
was obtained from column chromatography and the mixture was decomposing.
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Scheme 2 Plausible mechanism for the formation of naphthyl ketones
via the iodine-mediated reaction of 2-(2-phenylethynyl)-Morita–Baylis–
Hillman adducts.
Fig. 3 ORTEP diagram of the single-crystal X-ray structure of 4f.12
hydroxyl group then produces the unstable charged species
B via 6-endo-dig cyclization. Further, the proton transfer to
the carbonyl oxygen thus generates intermediate C. The inter-
mediate C leads to the formation of the intermediate D.
Subsequently, intermediate D is produced from the naphthyl
ketone derivative by the loss of an HI molecule, respectively
(Scheme 2).
Alternatively, we propose another mechanism in which the
reaction initiates by the formation of allylic carbocation inter-
mediate (I) from the reaction of the 2-(2-phenylethynyl)-MBH
adduct 1 in the presence of I2. The intermediate (I) may afford
intermediate III through path A or path B. Further, the inter-
mediate III undergoes enolization to produce the intermediate
IV. Finally, the intermediate IV upon aromatization in the pres-
ence of iodine leads to the formation of the desired naphthyl
ketone derivative (Scheme 3). The experimental results such as
the formation of allyliodide derivative (1d) and the formation
of the Ritter compound (1c) support the mechanistic route 2
(Scheme 3).
On the other hand, the formation of the iodo-substituted
isochromene derivative (e) or the dihydroisobenzofuran deriva-
tive (f) takes place via 6-endo-dig cyclization (pathway a) or
anti-5-exo-dig cyclization (pathway b) from the iodonium alk-
oxide intermediate A, which is generated from the reaction of
2-(2-phenylethynyl)-MBH adduct 1 in the presence of I2 and a
base (Scheme 4).
Scheme 1 Synthetic applications of iodo-substituted isochromene
derivatives.
To demonstrate the utility of this method, the presence of
an iodo group in the isochromene system can be further elabo-
rated using a palladium-catalyzed C–C bond coupling reaction
(Scheme 1). Compound 9b was treated with 4-methoxy phenyl
boronic acid under Suzuki reaction conditions to afford com-
pound 9c in 70% yield.
Based on the experimental results and previous literature
reports,10,11 we propose two plausible mechanistic routes for
the molecular I2 mediated reactions of 2-(2-phenylethynyl)-
MBH to naphthyl ketones as shown in Schemes 2 and 3.
Firstly, we propose that the reaction proceeds via the formation
of the 2-(2-phenylethynyl)-MBH adduct 1 in the presence of
I2, and the I+ ion co-ordinates with the triple bond of the
MBH-alkyne, which leads to the generation of the iodonium
intermediate A. The subsequent nucleophilic attack of the
Scheme 3 Plausible mechanism for the formation of naphthyl ketones via the iodine-mediated reaction of 2-(2-phenylethynyl)-Morita–Baylis–
Hillman adducts.
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hertz. IR spectra were recorded on an FT-IR spectrometer and
are reported in cm−1. Melting points were recorded using an
Electro Thermal capillary melting point apparatus and are
uncorrected. HRMS spectra were recorded using ESI-TOF or
EI+ mode.
Procedure for the synthesis of naphthyl ketone derivatives
(Table 2, entries 1–9)
Molecular iodine (3.0 equiv.) was added to a stirred solution of
the 2-(2-phenylethynyl)-MBH adduct (1.0 mmol) in dichloro-
methane (8.0 mL) at room temperature, and the reaction
mixture was then heated to 50 °C under a closed system and
monitored by TLC. After completion of the reaction, the solu-
tion was cooled to room temperature and the solvent was
removed under reduced pressure. Water was then added to the
reaction mixture and the resulting solution was extracted with
DCM (20 mL × 3). The combined organic layer was washed
with a saturated Na2S2O3 aqueous solution to remove the
excess iodine, dried over magnesium sulfate and filtered. The
solvent was evaporated at reduced pressure and the resulting
residue was further purified by column chromatography.
Scheme 4 Plausible mechanistic pathway for the formation of iodo-
substituted isochromene derivatives in the presence of iodine and a
base.
The failure to form naphthyl ketones in the presence of
iodine from the reactions of substrates containing nitro and
pyridyl groups of MBH-adducts (Table 2, entries 8 and 9) can
be explained by the proposed reaction mechanism. In both
cases, after the formation of intermediate B, the intermediate
C would not be formed (Scheme 2). In the former case it is due
to the electronic effect of the nitro group on the phenyl ring of
the MBH-adduct whereas in the latter case a pyridine moiety
on the MBH-adduct would act as a base and neutralize inter-
mediate B, leading to the formation of the iodo-substituted
isochromene derivative.
Procedure for the synthesis of iodo-substituted isochromes
and dihydroisobenzofurans (Table 4, entries 1–9)
Molecular iodine (3.0 equiv.) and potassium phosphate tri-
basic (K3PO4, 3.0 equiv.) were added to a stirred solution of
2-(2-phenylethynyl)-MBH adduct (1.0 mmol) in acetonitrile
(8.0 mL) at room temperature and the progress of the reaction
was monitored by TLC (the reaction temperature is mentioned
in the Table). After completion of the reaction, water was
added and the resulting solution was extracted with dichloro-
methane (20 mL × 3). The combined organic phase was
washed with aq. Na2S2O3 solution to remove excess iodine,
dried over magnesium sulfate and filtered. The solvent was
removed by evaporation at reduced pressure. The resulting
residue was further purified by column chromatography.
Conclusions
In conclusion, we report on the molecular iodine mediated
reaction of 2-(2-phenylethynyl)-MBH adducts using I2 and
I2/K3PO4 systems. In the presence of I2, naphthyl ketone
derivatives are formed, whereas in the case of the I2/K3PO4
system, iodo-substituted 1H-isochromene derivatives are
formed, which can be further used in C–C bond forming reac-
tions (Heck, Sonogashira and Suzuki reactions). Furthermore,
the conventional molecular iodine system is much more cost
effective than existing methods that involve the use of tran-
sition metals for the synthesis of naphthyl ketone derivatives.
We believe that this protocol provides a simple, efficient and
convenient alternative to the existing methodologies for produ-
cing a variety of substituted naphthyl ketones and 1H-iso-
chromene derivatives from the same starting materials in
good-to-moderate yields.
Preparation of 1-(3-methoxybuta-1,3-dien-2-yl)-4-(4-methoxy-
phenyl)-3-phenyl-1H-pyrano[4,3-b]quinoline (3c)
To 5.0 mL of a 3 : 1 ratio of DMF–H2O solution containing
compound 9b (0.5 mmol) and 4-methoxyphenylboronic acid
(0.6 mmol) was added PdCl2(PPh3)2 (5 mol%) and the reaction
mixture was stirred for 10 min. K2CO3 (2.5 equiv.) was then
added and the solution was stirred at 80 °C for 2 h under a
nitrogen atmosphere. The resulting reaction mixture was
extracted with ethyl acetate (2 × 10 mL). The combined organic
layers were dried over anhydrous MgSO4 and concentrated
under vacuum. The crude compound was then purified by
column chromatography to afford 9c as a yellow solid.
Experimental section
General information
Reagents and solvents were purchased from various commer-
cial sources and were used directly without any further purifi-
cation, unless otherwise stated. Column chromatography was
Spectral data of compounds
Methyl 4-benzoylnaphthalene-2-carboxylate (1b). Purified by
performed on 63–200 mesh silica gel. 1H and 13C NMR spectra column chromatography (EtOAc–hexane 10 : 90). Yield: 145 mg
were recorded at 400 and 100 MHz, respectively. Chemical (50%), starting from 292 mg of 1a (Table 2, entry 1). Yellow
shifts are reported in parts per million (δ) using CDCl3 as an solid; mp: 118–119 °C. FT-IR (KBr) (ν/cm−1): 1721, 1662. 1H
internal standard and coupling constants are expressed in NMR (400 MHz, CDCl3) δH (ppm): 8.76 (s, 1H), 8.16 (d,
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J = 1.64 Hz, 1H), 8.12–8.09 (m, 1H), 8.05–8.03 (m, 1H),
10-Benzoyl-1,2,3,4-tetrahydroanthracen-1-one (6b). Purified
7.89–7.86 (m, 2H), 7.64–7.60 (m, 3H), 7.48 (t, J = 7.74 Hz, 2H), by column chromatography (EtOAc–hexane 10 : 90). Yield:
3.97 (s, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 197.3, 150 mg (50%), starting from 302 mg of 6a (Table 2, entry 6).
166.6, 138.0, 137.0, 133.9, 133.7, 133.2, 133.1, 130.6, 130.0, Yellow gummy solid; FT-IR (KBr) (ν/cm−1): 1670, 1615, 1589.
129.7, 128.8, 127.4, 126.7, 126.3, 125.9, 52.6. LRMS (EI) (m/z) 1H NMR (400 MHz, CDCl3) δH (ppm): 8.77 (s, 1H), 8.05–8.02
(relative intensity): 290 (M+, 100), 213 (80), 105 (74). HRMS (m, 1H), 7.84–7.82 (m, 2H), 7.64–7.61 (m, 1H), 7.52–7.45 (m,
calcd for C19H14O3 (M+): 290.0943, found 290.0948.
Methyl
8-benzoyl-2H-naphtho[2,3-d][1,3]dioxole-6-carb- 13C NMR (100 MHz, CDCl3) δC (ppm): 199.5, 198.1, 137.4,
5H), 2.77–2.74 (m, 2H), 2.13–2.11 (m, 2H), 1.57–0.40 (m, 2H).
oxylate (2b). Purified by column chromatography (EtOAc– 136.1, 135.9, 134.4, 133.0, 131.6, 130.6, 130.5, 130.4, 129.9,
hexane 10 : 90). Yield: 174 mg (52%), starting from 336 mg of 129.6, 129.2, 126.6, 125.1, 39.6, 27.7, 23.0. LRMS (EI) (m/z)
2a (Table 2, entry 2). White solid; mp: 179–180 °C. FT-IR (KBr) (relative intensity): 300 (M+, 100), 299 (45), 215 (25), 105 (35).
(ν/cm−1): 1714, 1651. 1H NMR (400 MHz, CDCl3) δH (ppm): HRMS calcd for C21H16O2 (M+): 300.1150, found 300.1151.
8.53 (s, 1H), 8.01 (d, J = 1.44 Hz, 1H), 7.85–7.83 (m, 2H), 7.61
Methyl 4-benzoylphenanthrene-2-carboxylate (7b). Purified
(t, J = 7.38 Hz, 1H), 7.49–7.45 (m, 3H), 7.27–7.26 (m, 1H), 6.08 by column chromatography (EtOAc–hexane 10 : 90). Yield:
(s, 2H), 3.93 (s, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 204 mg (60%), starting from 342 mg of 7a (Table 2, entry 7).
197.5, 166.8, 151.1, 148.7, 138.1, 135.6, 133.6, 132.6, 131.2, Yellow solid; mp: 150–151 °C. FT-IR (KBr) (ν/cm−1): 1721, 1667,
130.8, 130.6, 128.7, 126.1, 124.8, 105.5, 102.6, 102.0, 52.5. 1596. 1H NMR (400 MHz, CDCl3) δH (ppm): 8.73 (d, J =
LRMS (FAB) (m/z) (relative intensity): 335 (M+, 100), 259 (36), 1.76 Hz, 1H), 8.20 (d, J = 8.48 Hz, 1H), 8.13 (d, J = 1.76 Hz, 1H),
219 (35), 105 (50). HRMS (FAB) calcd for C20H15O5 (M+): 7.91–7.85 (m, 5H), 7.58–7.52 (m, 2H) 7.42–7.33 (m, 3H), 3.98
335.0919, found 335.0916.
(s, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 199.7, 166.5,
1-(4-Benzoylnaphthalen-2-yl)ethan-1-one (3b). Purified by 138.6, 137.0, 134.2, 134.0, 133.0, 132.6, 131.4, 130.5, 129.2,
column chromatography (EtOAc–hexane 10 : 90). Yield: 150 mg 129.1, 129.0, 128.6, 128.0, 127.6, 127.3, 126.9, 126.8, 52.6.
(55%), starting from 276 mg of 3a (Table 2, entry 3). White LRMS (FAB) (m/z) (relative intensity): 341 (M+ + H, 100), 136
solid. mp: 117–118 °C. FT-IR (KBr) (ν/cm−1): 1680, 1661, 1619. (71), 105 (40). HRMS (FAB) calcd for C23H17O3 (M+): 341.1178,
1H NMR (400 MHz, CDCl3) δH (ppm): 8.61 (s, 1H), 8.13 (d, J = found 341.1173.
1.6 Hz, 1H), 8.10–8.05 (m, 2H), 7.88–7.86 (m, 2H), 7.65–7.61
Methyl 2-(4-iodo-7-nitro-3-phenyl-1H-isochromen-1-yl)prop-
(m, 3H), 7.48 (t, J = 7.76 Hz, 2H), 2.74 (s, 3H). 13C NMR 2-enoate (8b). Purified by column chromatography (EtOAc–
(100 MHz, CDCl3) δC (ppm): 197.5, 197.3, 137.9, 137.3, 133.8, hexane 10 : 90). Yield: 323 mg (70%), starting from 337 mg of
133.3, 133.2, 133.2, 132.9, 130.6, 130.3, 129.9, 128.8, 127.6, 8a (Table 2, entry 8). Yellow solid; mp: 142–143 °C. FT-IR (KBr)
126.0, 125.4, 26.8. LRMS (EI) (m/z) (relative intensity): 274 (ν/cm−1): 1722, 1607, 1573. 1H NMR (400 MHz, CDCl3)
(M+, 100), 259.0 (90), 197 (65), 105 (75). HRMS calcd for δH (ppm): 8.22 (dd, J = 8.64, 2.24 Hz, 1H), 7.82 (d, J = 2.08 Hz,
C19H14O2 (M+): 274.0994, found 274.0992.
1H), 7.69 (d, J = 8.64, Hz, 1H), 7.58–7.55 (m, 2H), 7.43–7.40 (m,
1-(4-Benzoyl-7-methoxynaphthalen-2-yl)ethan-1-one
(4b). 3H), 6.63 (s, 1H), 6.35 (s, 1H), 5.67 (s, 1H), 3.88 (s, 3H).
Purified by column chromatography (EtOAc–hexane 10 : 90). 13C NMR (100 MHz, CDCl3) δC (ppm): 165.9, 157.9, 147.1,
Yield: 155 mg (51%), starting from 306 mg of 4a (Table 2, 139.8, 137.0, 135.7, 131.0, 130.6, 130.5, 130.2, 129.9, 128.2,
entry 4). White solid; mp: 133–134 °C. FT-IR (KBr) (ν/cm−1): 124.5, 120.1, 75.7, 70.3, 52.7. LRMS (FAB) (m/z) (relative inten-
1
1680, 1619, 1592. H NMR (400 MHz, CDCl3) δH (ppm): 8.51 (s, sity): 463 (M+, 71), 338 (83), 136 (70), 105 (56). HRMS (FAB)
1H), 8.01–7.96 (m, 2H), 7.87–7.85 (m, 2H), 7.62–7.60 (m, 1H), calcd for C19H14O5N1 (M+): 462.9917, found 462.9905.
7.47 (t, J = 7.72 Hz, 2H), 7.34 (d, J = 2.56 Hz, 1H), 7.29–7.26 (m,
Methyl
2-{4-iodo-3-phenyl-1H-pyrano[4,3-b]quinolin-1-yl}-
1H), 3.97 (s, 3H), 2.72 (s, 3H). 13C NMR (100 MHz, CDCl3) δC prop-2-enoate (9b). Purified by column chromatography
(ppm): 197.6, 197.5, 158.7, 138.0, 137.2, 134.8, 133.8, 133.7, (EtOAc–hexane 10 : 90). Yield: 352 mg (75%), starting from
131.5, 130.6, 128.8, 128.6, 127.4, 123.4, 122.6, 107.9, 55.6, 26.9. 343 mg of 9a (Table 2, entry 9). Yellow solid; mp: 112–113 °C.
LRMS (EI) (m/z) (relative intensity): 304 (M+, 100), 289 (44), 227 FT-IR (KBr) (ν/cm−1): 1723, 1603, 1581. 1H NMR (400 MHz,
(22). HRMS calcd for C20H16O3 (M+): 304.1099, found 304.1106.
CDCl3) δH (ppm): 8.17 (d, J = 8.44 Hz, 1H), 7.75 (d, J = 8.04 Hz,
Ethyl 4-benzoylnaphthalene-2-carboxylate (5b). Purified by 1H), 7.72–7.66 (m, 3H), 7.64 (s, 1H), 7.48 (t, J = 7.52 Hz, 1H),
column chromatography (EtOAc–hexane 10 : 90). Yield: 213 mg 7.46–7.42 (m, 3H), 6.62 (s, 1H) 6.51 (s, 1H), 5.77 (s, 1H), 3.87
(70%), starting from 306 mg of 5a (Table 2, entry 5). White (s, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 166.13, 160.2,
solid; mp: 82–83 °C. FT-IR (KBr) (ν/cm−1): 1717, 1662, 1596. 1H 149.5, 148.4, 138.0, 136.4, 131.8, 130.5, 130.4, 130.3, 130.1,
NMR (400 MHz, CDCl3) δH (ppm): 8.75 (s, 1H), 8.16 (d, J = 129.6, 128.0, 127.9, 127.5, 126.6, 124.0, 76.4, 52.6. LRMS (FAB)
1.36 Hz, 1H), 8.08–8.02 (m, 2H), 7.88–7.86 (m, 2H), 7.63–7.58 (m/z) (relative intensity): 470 (M+, 100), 469 (32), 105 (28).
(m, 3H), 7.47 (t, J = 7.72 Hz, 2H), 4.44 (q, J = 7.12 Hz, 2H), 1.42 HRMS (FAB) calcd for C22H17O3N1 (M+): 470.0253, found
(t, J = 7.12 Hz, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 197.5, 470.0259.
166.2, 138.0, 137.1, 133.8, 133.7, 133.2, 133.1, 130.6, 130.0, 129.6,
Methyl 2-(4-iodo-3-phenyl-1H-isochromen-1-yl)prop-2-enoate
128.8, 127.4, 126.8, 126.7, 125.9, 61.6, 14.5. LRMS (FAB) (m/z) (1e). Purified by column chromatography (EtOAc–hexane
(relative intensity): 305 (M+ + H, 100), 259 (15), 105 (33). HRMS 5 : 95). Yield: 258 mg (62%), starting from 292 mg of 1a
(FAB) calcd for C20H17O3 (M+ + H): 305.1178, found 305.1174.
(Table 4, entry 1). Colorless solid; mp: 93–94 °C. FT-IR (KBr)
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(ν/cm−1): 1721, 1621. 1H NMR (400 MHz, CDCl3) δH (ppm): δC (ppm): 165.4, 151.8, 148.7, 146.1, 141.6, 138.8, 137.8, 130.1,
7.56–7.52 (m, 3H), 7.42–7.38 (m, 4H), 7.28–7.25 (m, 1H), 6.94 128.3, 128.2, 128.1, 126.6, 123.7, 117.8, 81.8, 68.8, 52.5. LRMS
(d, J = 7.36, 1H), 6.55 (m, 1H), 6.31 (s, 1H), 5.50 (s, 1H), 3.88 (s, (FAB) (m/z) (relative intensity): 463 (M+, 100), 378 (30), 337 (45).
3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 166.6, 153.7, 138.1, HRMS (FAB) calcd for C19H14O5N1I1 (M+): 462.9917, found
136.7, 133.5, 130.5, 130.3, 129.7, 129.6, 129.2, 129.1, 128.2, 462.9909.
128.0, 124.8, 75.5, 73.0, 52.5. LRMS (ESI) (m/z) (relative inten-
sity): 441 (M+ + Na, 30), 315 (100), 242 (70). HRMS (ESI) calcd Purified by column chromatography (EtOAc–hexane 5 : 95).
for C19H15O3NaI (M+ + Na): 440.9964, found 440.9961.
Yield: 120 mg (30%), starting from 276 mg of 3a (Table 4, entry
Methyl
2-[(3E)-3-[iodo(phenyl)methylidene]-1,3-dihydro-2- 6). Yellow solid; mp: 98–99 °C. FT-IR (KBr) (ν/cm−1): 1679,
3-(4-Iodo-3-phenyl-1H-isochromen-1-yl)but-3-en-2-one (5e).
1
benzofuran-1-yl]prop-2-enoate (1f). Purified by column 1592. H NMR (400 MHz, CDCl3) δH (ppm): 7.55–7.53 (m, 3H),
chromatography (EtOAc–hexane 5 : 95) (Table 3). White solid; 7.40–7.36 (m, 4H), 7.27–7.22 (m, 1H), 6.84 (d, J = 7.48 Hz, 1H),
mp: 102–103 °C. FT-IR (KBr) (ν/cm−1): 1718, 1644. 1H NMR 6.41 (d, J = 6.16 Hz, 2H), 5.79 (s, 1H), 2.49 (s, 3H). 13C NMR
(400 MHz, CDCl3) δH (ppm): 7.45–7.39 (m, 4H), 7.37–7.32 (m, (100 MHz, CDCl3) δC (ppm): 198.3, 154.1, 145.9, 136.6, 133.5,
2H), 7.21 (t, J = 7.5 Hz, 1H), 6.99 (t, J = 7.62, Hz, 1H), 6.45 (d, 130.5, 129.8, 129.7, 129.5, 129.0, 128.2, 128.0, 124.7, 74.5, 73.0,
J = 7.96 Hz, 1H), 6.40 (d, J = 5.72 Hz, 2H), 6.07 (s, 1H), 3.85 (s, 26.6. LRMS (EI) (m/z) (relative intensity): 402 (M+, 45), 303 (50),
3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 166.0, 156.1, 144.5, 105 (100). HRMS calcd for C19H15IO2 (M+): 402.0117, found
140.8, 138.9, 130.7, 130.2, 129.3, 129.2, 128.6, 128.4, 126.7, 402.0109.
123.3, 122.7, 81.9, 76.9, 64.4, 52.3. LRMS (ESI) (m/z) (relative
intensity): 419 (M+ + H, 100), 293 (11). HRMS (ESI) calcd for 1-yl]but-3-en-2-one (5f). Purified by column chromatography
C19H16O3I (M+ + H): 419.0144, found 419.0155.
(EtOAc–hexane 5 : 95). Yield: 140 mg (35%), starting from
3-[(3E)-3-[Iodo(phenyl)methylidene]-1,3-dihydro-2-benzofuran-
Methyl 2-(4-iodo-7-methoxy-3-phenyl-1H-isochromen-1-yl)- 276 mg of 3a (Table 4, entry 6). Yellow solid; mp: 102–103 °C.
prop-2-enoate (2e). Purified by column chromatography FT-IR (KBr) (ν/cm−1): 1673, 1645. 1H NMR (400 MHz, CDCl3)
(EtOAc–hexane 5 : 95). Yield: 259 mg (58%), starting from δH (ppm): 7.45–7.42 (m, 4H), 7.37–7.35 (m, 1H), 7.28–7.25
322 mg of 10a (Table 4, entry 2). Yellow liquid. FT-IR (KBr) (m, 1H), 7.19 (t, J = 7.48 Hz, 1H), 6.97 (t, J = 7.58 Hz, 1H), 6.51
(ν/cm−1): 1722, 1611. 1H NMR (400 MHz, CDCl3) δH (ppm): (s, 1H), 6.44 (d, J = 7.92 Hz, 1H), 6.25 (d, J = 7.44 Hz, 2H), 2.43
7.53–7.51 (m, 2H), 7.50–7.47 (m, 1H), 7.39–7.35 (m, 3H), 6.91 (s, 3H). 13C NMR (100 MHz, CDCl3) δC (ppm): 199.0, 156.2,
(dd, J = 8.6, 2.6 Hz, 1H), 6.55 (s, 1H), 6.52 (d, J = 2.56 Hz, 1H), 147.2, 145.0, 140.8, 130.7, 129.9, 129.4, 129.2, 128.6, 128.3,
6.26 (s, 1H), 5.51 (s, 1H), 3.88 (s, 3H), 3.82 (s, 3H). 13C NMR 126.5, 123.2, 123.0, 81.3, 64.4, 26.5. LRMS (EI) (m/z) (relative
(100 MHz, CDCl3) δC (ppm): 166.6, 159.8, 151.6, 137.8, 136.7, intensity): 402 (M+, 55), 126 (100). HRMS calcd for C19H15IO2
131.2, 130.5, 130.4, 129.4, 127.9, 126.5, 113.8, 110.7, 75.3, 72.8, (M+): 402.0117, found 402.0121.
55.7, 52.5. LRMS (ESI) (m/z) (relative intensity): 471 (M+ + Na,
76), 449 (M+, 80). HRMS (ESI) calcd for C20H18O4I (M+ + H): one (6e). Purified by column chromatography (EtOAc–hexane
3-(4-Iodo-7-methoxy-3-phenyl-1H-isochromen-1-yl)but-3-en-2-
449.0250, found 449.0240.
5 : 95). Yield: 273 mg (60%), starting from 306 mg of 4a
Methyl 2-[3-(2H-1,3-benzodioxol-5-yl)-4-iodo-1H-isochromen- (Table 4, entry 7). Yellow gummy solid. FT-IR (KBr) (ν/cm−1):
1
1-yl]prop-2-enoate (3e). Purified by column chromatography 1674, 1592. H NMR (400 MHz, CDCl3) δH (ppm): 7.537.51 (m,
(EtOAc–hexane 5 : 95). Yield: 300 mg (65%), starting from 2H), 7.47 (d, J = 8.56 Hz, 1H), 7.38–7.35 (m, 3H), 6.89 (dd, J =
336 mg of 11a (Table 4, entry 3). Yellow liquid. FT-IR (KBr) 8.56, 2.6 Hz, 1H), 6.44 (d, J = 2.56 Hz, 1H), 6.40 (s, 1H), 6.35 (s,
(ν/cm−1): 1722, 1623. 1H NMR (400 MHz, CDCl3) δH (ppm): 1H), 5.79 (s, 1H), 3.81 (s, 3H), 2.48 (s, 3H). 13C NMR (100 MHz,
7.52 (d, J = 7.8 Hz, 1H), 7.38 (t, J = 7.7 Hz, 1H), 7.26–7.22 CDCl3) δC (ppm): 198.3, 159.8, 152.0 145.7, 136.7, 131.1, 130.4,
(m, 1H), 7.08 (dd, J = 8.14, 1.62 Hz, 1H), 7.0–6.99 (m, 1H), 6.91 129.8, 129.5, 127.9, 126.6, 113.6, 110.7, 74.3, 72.7, 55.7, 26.6.
(d, J = 7.4 Hz, 1H), 6.81 (d, J = 8.12 Hz, 1H), 6.53 (s, 1H), 6.26 LRMS (ESI) (m/z) (relative intensity): 455 (M+ + Na, 35), 433 (M+
(s, 1H), 5.99 (s, 2H), 5.48 (s, 1H), 3.88 (s, 3H). 13C NMR + H, 65), 266 (100). HRMS (ESI) calcd for C20H17IO3Na
(100 MHz, CDCl3) δC (ppm): 166.6, 153.2, 148.7, 147.1, 137.9, (M+ + Na): 455.0120, found 455.0119.
133.7, 130.3, 129.6, 129.2, 129.1, 128.0, 125.3, 124.8, 110.9,
2-(4-Iodo-3-phenyl-1H-isochromen-1-yl)cyclohex-2-en-1-one
107.8, 101.5, 75.5, 72.3, 52.5. LRMS (FAB) (m/z) (relative inten- (7e). Purified by column chromatography (EtOAc–hexane
sity): 461.9 (M+, 100), 149 (50). HRMS (FAB) calcd for 5 : 95). Yield: 270 mg (60%), starting from 302 mg of 6a
C20H15O5I (M+): 461.9964, found 461.9958.
Methyl
dihydro-2-benzofuran-1-yl]prop-2-enoate
(Table 4, entry 8). Yellow solid; mp: 141–142 °C. FT-IR (KBr)
2-[(3E)-3-[iodo(phenyl)methylidene]-6-nitro-1,3- (ν/cm−1): 1673, 1588. 1H NMR (400 MHz, CDCl3) δH (ppm):
(4f). Purified by 7.55–7.52 (m, 3H), 7.39–7.35 (m, 4H), 7.72–7.21 (m, 1H), 6.83
column chromatography (EtOAc–hexane 5 : 95). Yield: 138 mg (d, J = 7.44 Hz, 1H), 6.77 (t, J = 4.14 Hz, 1H), 6.39 (s, 1H),
(30%), starting from 337 mg of 8a (Table 4, entry 4). Yellow 2.64–2.55 (m, 2H), 2.45–2.40 (m, 2H), 2.10–2.04 (m, 2H).
solid; mp: 136–137 °C. FT-IR (KBr) (ν/cm−1): 1717, 1634. 1H 13C NMR (100 MHz, CDCl3) δC (ppm): 198.0, 154.3, 150.8,
NMR (400 MHz, CDCl3) δH (ppm): 8.94 (d, J = 8.76 Hz, 1H), 136.9, 136.7, 133.8, 130.6, 130.1, 129.7, 129.4, 128.8, 128.1,
8.32 (dd, J = 8.78, 2.02 Hz, 1H), 8.21 (s, 1H), 7.55–7.53 (m, 2H), 127.9, 124.6, 73.4, 72.8, 38.6, 26.3, 22.8. LRMS (ESI) (m/z) (rela-
7.36 (t, J = 7.68 Hz, 2H), 7.26–7.25 (m, 1H), 6.31 (s, 1H), 6.24 (s, tive intensity): 429 (M+ + H, 100). HRMS (ESI) calcd for
1H), 5.88 (s, 1H), 3.81 (s, 3H). 13C NMR (100 MHz, CDCl3) C21H17IO2Na (M+ + Na): 451.0171, found 451.0179.
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2-[(3E)-3-[iodo(phenyl)methylidene]-1,3-dihydro-2-benzofuran- mentation Centre at National Taiwan Normal University are
1-yl]cyclohex-2-en-1-one (7f). Purified by column chromato- gratefully acknowledged.
graphy (EtOAc–hexane 5 : 95). Yield: 68 mg (15%), starting
from 302 mg of 6a (Table 4, entry 8). Colorless solid; mp:
108–109 °C; FT-IR (KBr): (ν/cm−1) 1668, 1596; 1H NMR
(400 MHz, CDCl3) δH (ppm): 7.45–7.41 (m, 4H), 7.39–7.36 (m,
Notes and references
1H), 7.35–7.31 (m, 1H), 7.19 (t, J = 7.48 Hz, 1H), 7.13–7.11 (m,
1H), 6.96 (t, J = 7.6 Hz, 1H), 6.50 (s, 1H), 6.43 (d, J = 7.92 Hz,
1H), 2.54–2.45 (m, 3H), 2.42–2.34 (m, 1H), 2.10–2.04 (m, 1H),
2.01–1.93 (m, 1H). 13C NMR (100 MHz, CDCl3) δC (ppm):
198.7, 156.3, 146.3, 145.7, 140.9, 138.3, 130.8, 129.8, 129.4,
129.2, 128.6, 128.1, 123.1, 123.1, 80.7, 64.0, 38.6, 25.9, 22.7.
LRMS (ESI) (m/z) (relative intensity): 451 (M+ + Na, 100), 429
(100). HRMS (ESI) calcd for C21H17IO2Na (M+ + Na): 451.0171,
found 451.0166.
Ethyl 2-(4-iodo-3-phenyl-1H-isochromen-1-yl)prop-2-enoate
(8e) and ethyl 2-[(3E)-3-[iodo(phenyl)methylidene]-1,3-dihydro-
2-benzofuran-1-yl]prop-2-enoate (8f). Purified by column
chromatography (EtOAc–hexane 5 : 95). Yield: 345 mg (80%),
starting from 292 mg of 5a (Table 4, entry 9). Yellow solid;
1H NMR (400 MHz, CDCl3) δH (ppm): 8.55–8.53 (m, 2H),
7.46–7.32(m, 9H), 7.27–7.20 (m, 2H), 6.99 (t, J = 7.58 Hz, 1H),
6.93 (d, J = 7.44 Hz, 1H), 6.52 (s, 1H), 6.45 (d, J = 7.92 Hz, 1H),
6.41 (s, 2H), 6.31 (s, 1H), 6.05 (s, 1H), 5.46 (s, 1H) 4.38–4.29
(m, 4H), 1.37–1.30 (m, 6H). 13C NMR (100 MHz, CDCl3) δC
(ppm): 166.1, 166.5, 156.1, 153.7, 144.6, 140.9, 139.1, 138.3,
136.7, 133.5, 130.7, 130.5, 130.3, 129.9, 129.7, 129.6, 129.3,
129.2, 129.2, 129.1, 128.6, 128.3, 128.1, 127.9, 126.7, 124.8,
123.2, 122.6, 82.1, 76.9, 75.5, 73.0, 64.3, 61.4, 61.2, 14.4, 14.4.
LRMS (FAB) (m/z) (relative intensity): 432 (M+, 100), 333 (36),
306 (62), 105 (32). HRMS (FAB) calcd for C20H17IO3 (M+):
432.0222, found 432.0223.
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Methyl
2-[4-(4-methoxyphenyl)-3-phenyl-1H-pyrano[4,3-b]-
quinolin-1-yl]prop-2-enoate (9c). Purified by column chromato-
graphy (EtOAc–hexane 15 : 90). Yield: 157 mg (70%), starting
from 171 mg of 9b. Yellow solid; mp: 154–155 °C. FT-IR (KBr)
(ν/cm−1): 1722, 1609. 1H NMR (400 MHz, CDCl3) δH (ppm):
7.99 (d, J = 8.4 Hz, 1H), 7.75–7.71 (m, 2H), 7.62–7.58 (m, 1H),
7.44–7.39 (m, 3H), 7.28–7.26 (m, 2H), 7.21–7.17 (m, 2H), 6.89
(d, J = 8.72 Hz, 2H), 6.63 (s, 1H) 6.55 (s, 1H), 5.83 (s, 1H), 3.91
(s, 3H), 3.82 (s, 3H). 13C NMR (100 MHz CDCl3) δC (ppm):
166.4, 158.7, 155.8, 151.4, 148.2, 138.6, 135.1, 133.5, 131.7,
130.0, 129.8, 129.7, 129.4, 128.8, 127.8, 127.6, 127.5, 127.1,
125.8, 124.4, 113.5, 75.7, 55.3, 52.5. LRMS (EI) (m/z) (relative
intensity): 449 (M+, 50), 344 (100), 284 (50), 246 (60), 105 (90).
HRMS calcd for C29H23N1O4 (M+): 449.1627, found 449.1628.
Acknowledgements
Financial support for this work by the National Science
Council of the Republic of China (NSC 100-2113-M-003-008-
MY3) and National Taiwan Normal University (99T3030-2,
99-D, and 100-D-06), Chiu-Hui He, Mei-Ling Chen, Ting-Shen
Kuo, for providing NMR, mass and crystal data, and the Instru-
This journal is © The Royal Society of Chemistry 2014
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8256 | Org. Biomol. Chem., 2014, 12, 8247–8256
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