Annulation of benzamides with [60]fullerene through palladium(II)-catalyzed C-H bond activation

Article abstract of DOI:10.1021/jo102107k

Palladium-catalyzed heteroannulation of N-substituted benzamides with [60]fullerene, which proceeds through direct sp2 C-H bond activation to form 7-membered ring pallada-intermediate with C60, led to formation of [60]fulleroisoquinolinones in moderate to good yields (8- 64% based on recovered C60). A plausible reaction pathway is proposed. 2011 American Chemical Society.

Full text of DOI:10.1021/jo102107k

ARTICLE
pubs.acs.org/joc
Annulation of Benzamides with [60]Fullerene through
Palladium(II)-Catalyzed C-H Bond Activation
Shih-Ching Chuang,*,† Venkatachalam Rajeshkumar,† Chun-An Cheng,† Jie-Cheng Deng,† and
Guan-Wu Wang*,‡
†Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, ROC 30010
‡Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
S Supporting Information
b
ABSTRACT: Palladium-catalyzed heteroannulation of N-sub-
stituted benzamides with [60]fullerene, which proceeds
through direct sp2 C-H bond activation to form 7-membered
ring pallada-intermediate with C60, led to formation of
[60]fulleroisoquinolinones in moderate to good yields (8-
64% based on recovered C60). A plausible reaction pathway is
proposed.
’ INTRODUCTION
0.0075 mmol, 15 mol %) and Oxone (22 mg, 0.15 mmol) in
o-DCB/TFA (6:1, v/v; 7 mL) at 120 °C in a sealed tube for 24 h;
we obtained the desired C60-fused isoquinolinone 2a in 10%
isolated yield (14% based on recovered C60) (Table 1, entry 1).
Thus, the formation of fulleroisoquinolinone was relatively poor
under these conditions; we explored reactions using other
oxidizing reagents and solvents in a quest for better yields. The
corresponding reactions performed using the common oxi-
dants Cu(OAc)2,4c,12,13 CH3COOAg,9 and Ag2O,10 under the stan-
dard conditions described above, improved the yields of 2a to 45,
26, and 23%, respectively (Table 1, entries 2-4). Next, we tested
the catalytic reaction using AcOH,11 DMSO,12 CH3CN,13 and
1-chloronaphthalene as cosolvents, but the resulting transforma-
tions were relatively less efficient (entries 5-8). The reactions
performed in chlorobenzene/TFA (10:1) gave 2a in 10% yield
with only a trace amount of recovered C60 (entry 9). The
addition of 1 equiv of water deteriorated the reaction perfor-
mance (entry 10). When reactions were carried out with 10 and
20 mol % of Pd(OAc)2, 2a was produced in 27 and 50% yield,
respectively (entries 11 and 12). It is noteworthy that increasing
the loading of Pd(OAc)2 from 10 to 50 mol % did not result in
obvious improvement of yields (entry 2 vs entries 11-14). This
was attributed to formation of higher adducts; we isolated
isomeric mixtures of bisadducts in 19 and 37% yields for 30
and 50 mol % loadings of Pd(OAc)2, respectively (entries 13 and
14). Without the presence of Cu(OAc)2 or excess loadings of
Cu(OAc)2, the yields were not improved; we only isolated 19
and 34% yields of 2a for 0 and 6 equiv loadings of Cu(OAc)2
(entries 15 and 16). Other organic reoxidizing reagent such as
benzoquinone did not give the desired product, but gave mostly
recovered C60 (entry 17).
Fullerene derivatives have an extensive range of applications.1
Although the functionalization of [60]fullerene using organic
methodologies is well established,2 studies of metal-catalyzed
methodologies for fullerene functionalization remain relatively
unexplored.3 Transition-metal catalysis is an efficient tool in
organic synthesis, enabling many diverse chemical transforma-
tions that are otherwise difficult to achieve using traditional
methods.4 Although C-H activation methodologies are well
established in common organic synthesis,5 their transfer to
fullerene chemistry is relatively poorly developed. Recently,
Wang et al. reported the Pd-catalyzed heteroannulations of
[60]fullerene with o-iodoanilines6 and anilides,7 initiated
through oxidative addition of aryl iodides to Pd(0) and C-H
bond activation, respectively. This methodology provides full-
eroindolines (five-membered rings) efficiently. Our research
program on application of transition-metal catalysis for functio-
nalizing C60 led us to study C-H activation of electron-poor
aromatics with fullerenes. We assume that benzamides could be
assembled with [60]fullerene to form fulleroisoquinolinones
(six-membered rings) using the recently reported conditions.7
However, these substrates are less reactive toward C-H activa-
tion under the described conditions because of the low electron
density on the phenyl ring. Herein, we report the efficient Pd-
catalyzed syntheses of the fulleroisoquinolinones 2 through C-
H bond activation of benzamides under relatively mild condi-
tions (Scheme 1).
’ RESULTS AND DISCUSSION
First, we synthesized the N-alkylated benzamides 1a-j ac-
cording to conventional methods.8 We used N-methylbenzamide
(1a) as a model substrate for our optimization studies. Initially,
we evaluated the reaction of C60 (36 mg, 0.050 mmol) with 1a
(20 mg, 0.15 mmol) in the presence of Pd(OAc)2 (1.68 mg,
Received: October 25, 2010
Published: February 23, 2011
r
2011 American Chemical Society
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Scheme 1. Heteroannulation of [60]Fullerene with N-Sub-
stituted Benzamides
Table 2. Palladium-Catalyzed Syntheses of the Fulleroiso-
quinolinones 2a-ja
entry
R
R0 amides product yieldb
(%)
yieldc
(%)
recovered
C60 (%)
1
H
H
H
Me
Et
1a
1b
1c
1d
1e
1f
2a
2b
2c
2d
2e
2f
45 (53) 44 (51)
44 (55) 47 (58)
28 (46) 19 (32)
42 (59) 40 (56)
53 (64) 57 (69)
52(59) 60 (67)
36 (51) 34 (48)
20 (26) 21 (27)
14
19
39
28
17
11
32
22
22
19
2
Table 1. Reactions of C60 with 1a under Various Conditionsa
3d
4d
5
Bn
Bn
Me
Et
4-Me
3-Me
3-Me
6
7d
4-OMe Bn
1g
1h
1i
2g
2h
2i
8
4-Cl
4-Ph
Et
9
i-Pr
Bn
6 (8)
5 (6)
10d 4-Ph
1j
2j
30 (37) 29 (36)
a All reactions were performed using 0.050 mmol of C60, 0.15 mmol of
the amide, 0.15 mmol of Cu(OAc)2, and 0.0075 mmol of Pd(OAc)2 in
ODCB/TFA (6:1, v/v; 7 mL) at 120 °C for 24 h unless otherwise noted.
b Isolated yields after column chromatography. Values in parentheses are based
on consumed C60. c Yields were measured by 1H NMR, using mesitylene as an
internal standard. d Reaction was performed using only 0.2 mL of TFA.
entry
oxidant
Oxone
solvents (mL)
yieldb (%)
1
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/AcOH (6:1)
o-DCB/DMSO (6:1)
o-DCB/CH3CN (6:1)
1-Cl-naphthalene/TFA (6:1)
PhCl/TFA(10:1)
10 (14)
45 (53)
26 (37)
23 (35)
4 (10)
<3
2
Cu(OAc)2
CH3COOAg
Ag2O
3
4
5
Cu(OAc)2
Cu(OAc)
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
none
the reaction carried out at 120 °C required good sealing for
prevention of TFA loss. We observed that TFA loss during the
reaction caused lower yielding results.
6
7
<3
8
14 (86)
10 (15)
21
With the optimal conditions in hand, we evaluated the
catalytic scope of this system by employing a variety of substrates
1b-j (Table 2) featuring either electron-donating and -with-
drawing groups on their benzamide aryl rings. In general,
substrates equipped with electron-donating groups afforded their
corresponding fulleroisoquinolinones in good yields (Table 2,
entries 4-7). Substrates 1e and 1f underwent regioselective C-
H activations7 at their less hindered and more electron-rich para
positions (relative to their Me substituents) to afford 2e and 2f in
excellent yields of 53 and 52%, respectively (Table 2, entries 5
and 6). Substrates bearing electron-withdrawing groups, such as
the chloro and phenyl units of 1h-j, provided their products in
only moderate yields (Table 2, entries 8-10). Under the
standard conditions, the reactions of amides bearing N-benzyl
substituents (1c, 1d, 1g, and 1j) yielded debenzylated products.
To overcome this problem, we performed these experiments
using only 0.2 mL of TFA to obtain the desired products in
moderate yields (Table 2, entries 3, 4, 7, and 10). The extremely
low yield of 2i may be attributed to the bulkiness of the isopropyl
group that makes formation of pallada-intermediate poor
(entry 9). We further surveyed the reaction yields using 10, 15,
and 20 mol % of Pd(OAc)2 catalysts under optimal conditions
and summarized the isolated yields measured by the weighing
method in Figure 1. We found that the yields obtained from
10 mol % of Pd(OAc)2 are relatively lower and those from 15 and
20 mol % of Pd(OAc)2 catalysts are higher and comparable (see
the Supporting Information for plots of yields on the basis of
recovered C60).
9
10c
11d
12d
13d
14d
15
16
17
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
o-DCB/TFA (6:1)
27 (84)
50 (61)
37 (43)g
0h
19 (54)
34 (40)
0i
e
Cu(OAc)2
benzoquinone f
a All reactions were performed with 0.050 mmol of C60, 0.15 mmol of 1a,
0.15 mmol of oxidant, and 0.0075 mmol of Pd(OAc)2 in the listed
solvent at 120 °C for 24 h unless otherwise noted. b Isolated yields after
column chromatography. Values in parentheses are based on consumed
C60. c Reaction performed with 1 equiv of H2O added. d Entries 11, 12,
13, and 14 were carried out with 10, 20, 30, and 50 mol % of Pd(OAc)2,
respectively. 6 equiv of Cu(OAc)2 was loaded. f 3 equiv of benzoqui-
e
none. g 19% bisadducts were isolated. h 37% bisadducts were isolated.
i 98% C60 was recovered.
Therefore, our systematic screening of a range of oxidants and
solvents revealed that the heteroannulation of [60]fullerene with
the N-substituted benzamide 1a was optimized when performed
in the presence of Cu(OAc)2 in ODCB/TFA (6:1), giving the
fulleroisoquinolinone 2a in good yield (45%; Table 1, entry 2).
Notably, TFA has been used as a solvent in organic syntheses for
the sp2 C-H bond activation of amides9 and oxime ethers.10
Since the reaction incorporated TFA as a cosolvent (bp 72.4 °C),
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We characterized the fulleroisoquinolinones 2a-j using infra-
atom C3 correlates with the protons on both C9 and C11, which
are three bonds away. We unambiguously assigned the quatern-
ary sp2-hybridized carbon atoms C4, C5, and C8 through their
three-bond correlations with the protons on the C6, C7/C9, and
C6 atoms, respectively. Notably, all of the signals of the sp2-
hybridized aryl protons of the fulleroisoquinolinones appear
downfield away from CHCl3 (7.26 ppm). Figure 3 presents the
structure of compound 2d determined using X-ray diffraction
analysis.14
Scheme 2 presents a plausible mechanism for the formation of
the fulleroisoquinolinones. Complexation of Pd(II) with the
nitrogen atom in amides 1a-j, followed by ortho C-H activa-
tion, results in the formation of a five-membered-ring palladacyle
Ia.15 Subsequent insertion of C60 to intermediate Ia generates
intermediate Ib. Finally, reductive elimination affords the full-
eroisoquinolinones 2a-j and Pd(0), which is oxidized to Pd(II)
by Cu(OAc)2 to complete the catalytic cycle.
Next, we compared the electrochemical and UV-vis spectro-
scopic properties of the structurally similar six- (fulleroisoqui-
nolinones) and five-membered-ring (fulleroindolines) com-
pounds. Table 3 summarizes the half-wave reduction potentials
of the isomeric compounds 2a and 3a.7 To our surprise, the
fulleroisoquinolinone 2a exhibits its first reduction potential at -
1.14 V, which is only 10 mV more negative than that of C60; we
observed similar trends in the values of its second (-1.52 V) and
third (-1.99 V) reduction potentials, suggesting that attachment
of the electronegative nitrogen atom to the sp3-hybridized
carbon atom of the fullerene cage compensates for the reduced
potentials typically imparted after monofunctionalization. In
contrast, the five-membered-ring fulleroindoline 3a underwent
an inherently lower first reduction at -1.17 V, consistent with
the observations of Suzuki et al., who found that five-membered-
ring fullerene derivatives generally exhibit more-negative
potentials.16 Again, this behavior is consistent with the notion
1
red (IR) and H and 13C nuclear magnetic resonance (NMR)
spectroscopy, fast atom bombardment mass spectrometry (FAB
MS), and X-ray crystallography. All MS data corresponded to the
expected formulas of the isolated fulleroisoquinolinones. Be-
cause each of these compounds possesses a symmetrical plane, its
13C NMR spectrum exhibits 30 peaks for the sp2-hybridized
carbon atoms on the C60 cage. In their IR spectra, CdO
stretching bands appear at ca. 1650 cm-1. Figure 2 displays a
2D-HMBC spectrum of the selected compound 2f. We made
partial peak assignments on the basis of one- (2D-HMQC) and
three-bond (2D-HMBC) correlation spectra. For example, the
signals of the protons on the C6, C7, C9, C10, C11, and C12
atoms of 2f were readily assignable in terms of their one-bond
couplings, according to the 2D-HMQC data (see the Supporting
Information). The sp3-hybridized carbon atoms of the C60
moiety of 2f appear as two signals at 62.60 (C1) and 79.29
(C2) ppm; C1 and C2 correlate with the protons on C6 and C11,
respectively, through three-bond couplings. The CdO carbon
Figure 1. Summary of reaction yields using 10 (white), 15 (gray), and
20 mol % (black) Pd(OAc)2 catalysts under optimal conditions.
Figure 2. 2D-HMBC spectrum of compound 2f.
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However, the products would become relatively unreactive
under the cosolvent of trifluoroacetic acid due to protonation.
This manner will retard them for further being functionlized to
form higher adducts. Finally, the electronic absorptions of 2a and
3a in their UV-vis spectra were nearly identical; they both
feature typical absorptions at 426 nm and extended absorption at
688 nm, consistent with those of corresponding fullerene
monoadducts.7
In conclusion, fulleroisoquinolinones can be prepared effi-
ciently from heteroannulations of [60]fullerene with N-alkyl-
benzamides through C-H bond activation under Pd(II)
catalysis. We used trifluoroacetic acid as a key cosolvent for
improving the reaction performance. The isolated fulleroisoqui-
nolinones are easier to be reduced as compared to their 5-mem-
bered-ring isomers according to electrochemical studies.
Extensions of this study to the syntheses of isoquinolinones
using alkynes are underway.
Figure 3. X-ray crystal structure of compound 2d.
Scheme 2. Proposed Reaction Pathway
’ EXPERIMENTAL SECTION
General Procedure for the Synthesis of [60]Fullero-
isoquinolinone 2. To a pressure-affordable thick-wall glass tube
containing C60 (36 mg, 0.05 mmol), benzamide 1 (0.15 mmol),
Pd(OAc)2 (1.68 mg, 0.0075 mmol), and Cu(OAc)2 (27 mg,
0.15 mmol) were added 6 mL of dry o-dichlorobenzene, 1 mL of
TFA, and a stir bar. The tube was sealed with an O-ring and
Teflon cap. After the tube was stirred at 120 °C without loss of
TFA (bp 72.4 °C) for 24 h, the reaction mixture was cooled to
room temperature and then subjected to column chromato-
graphy using toluene as a starting eluent for recovery of the
unreacted C60. Subsequent elution with 2% ethyl acetate in
toluene afforded fulleroisoquinolinone 2. Spectral data of com-
pound 2a-j follow.
Table 3. Half-Wave Reduction Potentials (V)a of C60, 2a, 3a,
and 3b
Spectral data of compound 2a: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 4.11 (s, 3H), 7.63 (dt, J = 7.3, 1.0 Hz, 1H), 7.74
(dt, J = 1.7 Hz, 7.2 Hz, 1H), 8.65 (dd, J = 1.6 Hz, 8.1 Hz, 2H); 13C
NMR (176.0 MHz, CS2/CDCl3 = 1:2, with Cr(acac)3 as
relaxation reagent) 33.5, 62.1, 79.5, 125.8, 128.0, 128.4, 130.0,
132.8, 133.63, 134.1, 135.4, 138.1, 139.3, 140.9, 141.17, 141.23,
141.7, 142.2, 142.3, 142.6, 142.7, 143.0, 144.3, 144.5, 144.9,
145.0, 145.1, 145.2, 145.7, 145.8, 146.0, 146.1, 146.4, 146.5,
146.8, 147.6, 148.1, 155.4, 161.9; FT-IR (KBr) ν (cm-1) 526,
554, 728, 901, 1374, 1465, 1653; HRMS (FABþ) calcd for
C68H8NO (M þ 1) 854.0606 found 854.0620.
compd
E1
E2
E3
C60
2a
-1.13
-1.14
-1.17
-1.13
-1.52
-1.52
-1.54
-1.50
-1.98
-1.99
-1.92
-1.99
3a
3b16
a Versus ferrocene/ferrocenium. Conditions: ca. 0.50 mM of C60, 2a, or
3a and 0.050 mM Bu4NPF6 in anhydrous o-DCB; reference electrode:
Ag/0.01 M AgNO3 and 0.050 mM n-Bu4NClO4 in anhydrous acetoni-
trile; working electrode: glassy carbon; auxiliary electrode: Pt; scanning
rate: 20 mV s-1
.
Spectral data of compound 2b: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 1.52 (t, J = 6.9 Hz, 3H), 4.87 (q, J = 6.9 Hz, 2H),
7.62 (dt, J = 1.1 Hz, 8.1 Hz, 1H), 7.73 (dt, J = 1.8 Hz, 8.0 Hz, 1H),
8.66 (d, J = 8.2 Hz, 2H); 13C NMR (176.0 MHz, CS2/CDCl3 =
1:2, with Cr(acac)3 as relaxation reagent) 15.0, 40.2, 62.6, 79.1,
125.7, 127.8, 129.6, 130.0, 132.5, 133.2, 133.6, 135.3, 138.0,
139.1, 140.9, 141.1, 141.3, 141.6, 142.17, 142.19, 142.5, 142.6,
142.9, 144.3, 144.3, 144.5, 144.7, 144.9, 144.99, 145.02, 145.6,
145.8, 145.9, 146.0, 146.3, 146.4, 147.4, 147.5, 148.0, 155.3,
160.2; FT-IR (KBr) ν (cm-1) 526, 738, 830, 1199, 1310, 1398,
that attachment of a heteroatom to an sp3-hybridized carbon
atom of a C60 cage shifts the reductive waves anodically (cf.
values for 3b in Table 3). Notably, we observed similar reduction
potentials when analyzing these compounds using differential
pulse voltammetry and Osteryoung square wave voltammetry.8
Furthermore, the first reduction potential of the monoadducts
is nearly the same as that of C60, indicating that they should
have nearly the same reactivity toward further functionalization.
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1462, 1514, 1653; HRMS (FABþ) calcd for C69H10NO (M þ 1)
868.0762 found 868.0760.
Spectral data of compound 2h. 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 1.51 (t, J = 6.9, 3H), 4.85 (q, J = 6.9 Hz, 2H), 7.59
(dd, J = 1.9, 8.4 Hz, 1H), 8.59 (s, 1H), 8.62 (s, 1H); 13C NMR
(176.0 MHz, CS2/CDCl3 = 1:2, with Cr(acac)3 as relaxation
reagent) 14.7, 40.3, 62.2, 79.3, 124.1, 128.4, 129.6, 131.5, 133.8,
135.2, 135.3, 138.0, 139.39, 139.5, 141.0, 141.1, 141.3, 141.5,
142.19, 142.22, 142.6, 142.7, 143.0, 144.2, 144.3, 144.5, 144.6,
144.9, 144.98, 145.04, 145.6, 145.8, 145.9, 146.0, 146.38, 146.44,
Spectral data of compound 2c: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 6.07 (s, 2H), 7.08-7.19 (m, 3H), 7.31 (d, J = 7.4
Hz, 2H), 7.66 (t, J = 7.3 Hz, 1H), 7.77 (dt, J = 1.5 Hz, 7.7 Hz,
1H), 8.69 (dd, J = 1.8 Hz, 8.1 Hz, 2H); 13C NMR (150.7 MHz,
CS2/CDCl3 = 1:2) 48.39, 63.1, 79.7, 125.8, 126.9, 127.2, 128.2,
128.4, 129.8, 130.6, 133.2, 133.9, 134.4, 135.4, 139.4, 141.1,
141.4, 141.8, 142.39, 142.42, 142.8, 142.9, 143.1, 144.5, 144.5,
144.7, 145.0, 145.2, 145.3, 145.8, 146.0, 146.1, 146.2, 146.56,
147.1, 147.6, 148.1, 154.7, 159.9; FT-IR (KBr) ν (cm-1
)
526, 766, 1064, 1150, 1308, 1418, 1457, 1512, 1540, 165;
HRMS (FABþ), calcd for C69H9ClNO (M þ 1) 902.0373 found
902.0361.
146.63, 147.5, 147.8, 148.3, 155.5, 162.5; FT-IR (KBr) ν (cm-1
)
526, 736, 970, 1030, 1321, 1393, 1451, 1513, 1541, 1651;
HRMS (FABþ) calcd for C74H12NO (M þ 1) 930.0919 found
930.0933.
Spectral data of compound 2i: 1H NMR (600 MHz, CS2/
CDCl3 = 1:2) δ 1.83 (d, J = 6.6 Hz, 6H), 5.85 (septet, 1H), 7.35
(m, 3H), 7.54 (dd, J = 1.0 Hz, 7.9 Hz, 2H), 7.79 (dd, J = 1.6 Hz,
8.2 Hz, 1H), 8.67 (d, J = 8.2 Hz, 1H), 8.76 (d, J = 1.5 Hz, 1H) ;
13C NMR (150.7 MHz, CS2/CDCl3 = 1:2, with Cr(acac)3 as
relaxation reagent) 20.7, 51.3, 63.7, 80.5, 125.7, 126.9, 127.2,
128.2, 128.6, 129.0, 130.3, 133.8, 133.9, 135.7, 137.8, 139.5,
139.8, 141.2, 141.3, 141.5, 141.8, 142.5, 142.8, 142.9, 143.2,
144.5, 144.76, 144.79, 144.9, 145.1, 145.2, 145.8, 146.1, 146.3,
146.6, 146.7, 147.6, 147.8, 148.3, 155.7, 161.7; FT-IR (KBr) ν
(cm-1) 527, 695, 749, 851, 1031, 1072, 1200, 1340, 1375, 1433,
1515, 1541, 1653; HRMS (FABþ) calcd for C76H16NO (M þ 1)
958.1232 found 958.1217.
Spectral data of compound 2d: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 2.54 (s, 3H), 6.09 (s, 2H), 7.08-7.23 (m, 3H),
7.31 (d, J = 7.4 Hz, 2H), 7.46 (d, J = 8.0 Hz, 1H), 8.43 (s, 1H),
8.58 (d, J = 8.0 Hz, 1H); 13C NMR (176.0 MHz, CS2/CDCl3 =
1:2, with Cr(acac)3 as relaxation reagent) 21.9, 47.8, 62.7, 79.3,
123.2, 126.6, 126.9, 128.1, 129.0, 129.9, 130.7, 133.6, 133.7,
135.1, 137.6, 137.8, 139.1, 140.8, 141.08, 141.10, 141.6, 142.10,
142.14, 142.5, 142.6, 142.7, 142.8, 143.5, 144.18, 144.23, 144.4,
144.7, 144.8, 144.9, 145.1, 145.5, 145.7, 145.8, 145.9, 146.26,
146.30, 147.5, 147.9, 155.3, 161.8; FT-IR (KBr) ν (cm-1
)
527, 6943, 973, 1122, 1183, 1379, 1414, 1513, 1540, 1651;
HRMS (FABþ) calcd for C75H14NO (M þ 1) 944.1075 found
944.1066.
Spectral data of compound 2j: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 6.10 (s, 2H), 7.09-7.26 (m, 2H), 7.35-7.46 (m,
6H), 7.60 (td, J = 1.5 Hz, 7.4 Hz, 2H), 7.87 (dd, J = 1.6 Hz, 8.2
Hz, 1H), 8.79 (d, J = 8.2 Hz, 1H), 8.87 (d, J = 1.5 Hz, 1H); 13C
NMR (150.7 MHz, CS2/CDCl3 = 1:2) 48.2, 63.1, 79.7, 124.5,
126.8, 127.0, 127.1, 127.2, 128.4, 128.5, 128.9, 129.0, 131.3,
133.9, 134.7, 137.7, 138.0, 139.5, 139.6, 141.1, 141.3, 141.8,
142.3, 142.4, 142.7, 142.8, 143.0, 144.4, 144.6, 145.0, 145.06,
145.10, 145.2, 145.7, 145.9, 146.07, 146.10, 146.2, 146.49, 146.54,
147.5, 147.7, 148.2, 155.4, 162.2; FT-IR (KBr) ν (cm-1) 527, 545,
695, 752, 972, 1031, 1122, 1215, 1384, 1408, 1436, 1606, 1650;
HRMS (FABþ) calcd for C80H16NO (M þ 1) 1006.1232, found
1006.1255.
Spectral data of compound 2e: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 2.59 (s, 3H), 4.11 (s, 3H), 7.55 (dd, J = 1.5 Hz, J
= 8.3 Hz, 1H), 8.45 (s, 1H), 8.52 (d, J = 8.2 Hz, 1H); 13C NMR
(150.7 MHz, CS2/CDCl3 = 1:2, with Cr(acac)3 as relaxation
reagent) 20.8, 33.5, 61.9, 79.5, 125.6, 129.5, 130.2, 131.1, 133.5,
133.6, 135.5, 137.8, 138.1, 139.3, 140.9, 141.15, 141.23, 141.8,
142.17, 142.23, 142.5, 142.6, 142.9, 144.3, 144.5, 144.8, 144.9,
145.1, 145.2, 145.71, 145.74, 145.9, 146.0, 146.3, 146.4, 146.9,
147.6, 148.1, 155.5, 161.7; FT-IR (KBr) ν (cm-1) 526, 578, 594,
761, 1061, 1362, 1424, 1465, 1513, 1541, 1655; HRMS (FABþ),
calcd for C69H10NO (M þ 1) 868.0762 found 868.0764.
Spectral data of compound 2f: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 1.51 (t, J = 6.9 Hz, 3H), 2.59 (s, 3H), 4.83 (q, J =
6.8 Hz, 2H), 7.52 (d, J = 8.3 Hz, 1H), 8.43 (s, 1H), 8.50 (d, J = 8.3
Hz, 1H); 13C NMR (150.7 MHz, CS2/CDCl3 = 1:2, with
Cr(acac)3 as relaxation reagent) 15.0, 20.8, 40.1, 62.3, 79.0,
125.5, 129.6, 130.19, 130.23, 133.3, 133.4, 135.3, 137.5, 137.9,
139.1, 140.8, 141.0, 141.3, 141.6, 142.10, 142.13, 142. 5, 142.6,
142.9, 144.2, 144.3, 144.4, 144.6, 144.8, 144.9, 145.0, 145.5,
145.7, 145.8, 145.9, 146.2, 146.3, 147.4, 147.5, 147.9, 155.4,
160.1; FT-IR (KBr) ν (cm-1) 526, 578, 766, 1069, 1185, 1319,
1380, 1425, 1462, 1513, 1650; HRMS (FABþ) calcd for
C70H12NO (M þ 1) 882.0919, found 882.0910.
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental procedures and
b
full spectroscopic/spectrometric data (IR; 1H and 13C NMR) for
all new compounds; X-ray crystallographic data for compound
2d (CIF). This material is available free of charge via the Internet
at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Corresponding author. jscchuang@faculty.nctu.edu.tw; gwang@
ustc.edu.cn.
Spectral data of compound 2g: 1H NMR (300 MHz, CS2/
CDCl3 = 1:2) δ 3.92 (s, 3H), 6.06 (s, 2H), 7.10-7.23 (m, 4H),
7.33 (d, J = 7.4 Hz, 2H), 8.13 (d, J = 1.9 Hz, 1H), 8.67 (d, J = 8.6
Hz, 1H); 13C NMR (150.7 MHz, CS2/CDCl3 = 1:2) 48.1, 55.5,
63.1, 79.7, 113.4, 116.3, 118.9, 126.8, 127.2, 128.4, 133.0, 133.9,
135.3, 136.3, 138.0, 138.1, 139.5, 141.1, 141.4, 141.8, 142.39,
142.42, 142.7, 142.8, 143.0, 143.1, 144.5, 144.5, 144.7, 145.0,
145.16, 145.21, 145.3, 145.8, 146.0, 146.1, 146.2, 146.56, 146.60,
’ ACKNOWLEDGMENT
We thank the National Science Council for financial support
of this research (NSC962113-M009-028-MY2 and NSC982119-
M009-001-MY2).
147.8, 147.9, 148.3, 155.5, 162.4, 163.5; FT-IR (KBr) ν (cm-1
)
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