Organocatalyzed arylalkylation of activated alkenes via decarboxylation of PhI(O2CR)2: Efficient synthesis of oxindoles

Article abstract of DOI:10.1016/j.tet.2012.03.051

A novel organocatalyzed arylalkylation of activated alkenes has been developed. This reaction was initiated from the decomposition of PhI(O ₂CR)₂ to generate alkyl radical, followed by addition to alkenes. Then the formed radical was trapped by aromatic ring to generate the cyclized products. This method presents an efficient road to synthesis of a variety of oxindoles.

Full text of DOI:10.1016/j.tet.2012.03.051

Tetrahedron 68 (2012) 5229e5233
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Tetrahedron
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Organocatalyzed arylalkylation of activated alkenes via decarboxylation
of PhI(O2CR)2: efficient synthesis of oxindoles
*
Tao Wu, Hao Zhang, Guosheng Liu
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel organocatalyzed arylalkylation of activated alkenes has been developed. This reaction was ini-
tiated from the decomposition of PhI(O2CR)2 to generate alkyl radical, followed by addition to alkenes.
Then the formed radical was trapped by aromatic ring to generate the cyclized products. This method
presents an efficient road to synthesis of a variety of oxindoles.
Received 10 January 2012
Received in revised form 5 March 2012
Accepted 15 March 2012
Available online 29 March 2012
Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
Keywords:
Organocatalyzed
Decarboxylation
Difunctionalization
Alkenes
Radical cyclization
1. Introduction
A
Difunctionalization of alkenes is an important transformation in
organic chemistry, and have been extensively investigated in the
last several decades. Among those reactions, transition metal
generally exhibits excellent reactivity and selectivity.1 For instance,
palladium-catalyzed oxidative difunctionalization of alkenes pres-
ents one of most efficient way to achieve directed transformation of
alkenes to a variety of vicinal functionalized compounds,2 such as
aminoalcohol,3 diamine,4 diol,5 and aminohalides.6 In contrast,
oxidative dicarbonation of alkene is less reported.7
B
Scheme 1. Organocatalyzed reactions.
Recently, Lei,8 Shi,9 and Hayashi10 independently reported
a metal-free reaction between aryliodide and aromatic compounds
in the present of KOtBu (Scheme 1A). Notable, organocatalysis plays
an important role in those transformations.11 Herein, we reported
a metal free arylalkylation of alkenes. This reaction involves a rad-
ical pathway, and the initial alkyl radical generates from de-
carboxylation of hypervalent dicarboxylate iodide reagent (Scheme
1B).12,13 It is worth noting that a bisnitrogen ligand plays a signifi-
cant effect on this transformation.
CeH bond cleavage.14 During the optimization reaction condition,
we found that the reaction afforded 56% yield of 2a in the presence
of AgF. Interestingly, the unexpected product 3a derived from ad-
dition of two carbon nucleophiles cross double bond was obtained
in the reaction with CsF as base, albelt in low yield (Eq.1). And these
two carbon nucleophiles were generated from CeH cleavage of
aniline and decarboxylation of carboxylic acid, respectively.
2. Results and discussion
Very recently, our group reported a palladium-catalyzed oxi-
dative arylalkylation of activated alkenes, which involves a dual
* Corresponding author. E-mail address: gliu@mail.sioc.ac.cn (G. Liu).
0040-4020/$ e see front matter Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.03.051

5230
T. Wu et al. / Tetrahedron 68 (2012) 5229e5233
group on nitrogen did not yield the desired products 3b and 3c
Above observation promoted us to explore this transformation.
(entries 2 and 3). For the substrate bearing fluoride (1d) or chloride
(1e) in aromatic ring, the reaction presented similar reactivity to
give high yields (entries 4 and 5). However, the active substrate
with bromide (1f) or iodide (1g) gave slightly lower yield (entries 6
and 7). Moreover, when substrate has an electron-withdrawing
group, such nitro (1h), trifluoromethyl (1i), and ester (1j) group,
the reaction afforded the corresponding oxindole product in low
yields (entries 8e10). In contrast, substrate with electron-donating
group afforded the desired products 3kes in good to excellent
yields. The position of the substituents on the aryl ring had no
significant influence on the efficiency (entries 12 and 14). The
substrates having two substituents on the aryl ring were still good
for this transformation (3per). Finally, substrate (1t), without
a substituent at the position of the olefin, did not afford the desired
product 3t.
As we mentioned above, this reaction was involved a tert-butyl
radical, which was generated from the decomposition of PhI(O-
Piv)2. In contrast, the methyl radical is less stable than tert-butyl
radical. Thus, the reaction of PhI(OAc)2 was further studied. It is
delighted that the reaction of 1a with PhI(OAc)2 proceeded
smoothly to afford desired decarboxylation product 4 in 71% yield,
with recovery of 21% 1a (Eq. 2).16 This observation presented an
efficient method to introduce a methyl into molecules. When 1a
was treated with the same reaction condition except with PhI(O-
Piv)2 instead of PhI(OAc)2, the reaction afforded the mixture of 3a
and 4 with a ratio of 5:1 (Eq. 3). Furthermore, the similar results
were obtained in the previous catalytic system (Eqs. 4 and 5). Those
observations suggested that an equilibrium was existed between
PhI(OAc)2 and PhI(OPiv)2 in the presence of HOAc or HOPiv, and the
decarboxylation of PhI(OPiv)2 is much easy than that of PhI(OAc)2.
As shown in Table 1, the screening results of the base indicated that
CsOPiv exhibited better reactivity than other bases, such as CsF and
NaOPiv (entries 1e3). Further studies exhibited that a bidentate
nitrogen-containing ligand is beneficial to the reaction, and the li-
gand L3 was shown to give the best yield (entries 4e7, Fig. 1). When
CaCO3 was added, the reaction yield was increased to 48% (entry 8).
Obvious solvent effect was also observed, and DMA (N,N-dimethyl
acetamide) was proven to be the best for this reaction (entries
8e12). Elevating the reaction temperature, the reaction yielded the
highest results at 110 ꢀC (entries 13 and 14). Surprisingly, the
controlling experiments showed that Palladium catalyst was not
necessary, and a similar yield was given. But the reaction yield was
significant reduced in the absence of ligand L3 (entries 15 and16).
In addition, the reaction was inhibited by employing 2,2,6,6-
tetramethyl-1-piperidinyloxyl (TEMPO) as a radical scavenger,
which suggested that a radical pathway should be involved.15 No-
table, the dinitrogen ligand plays an important role to promote this
radical cyclization.
Table 1
Screening resultsa
Entry
Base
Ligand
Solvent
Temp
Yield (3a)
1
2
3
4
5
6
CsF
d
d
d
L1
L2
L3
L4
L3
L3
L3
L3
L3
L3
L3
L3
d
L3
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
DMA
Dioxane
Toluene
NMP
DMA
DMA
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
80 ꢀC
5%
18%
0
CsOPiv
NaOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
CsOPiv
23%
31%
37%
21%
48%
78%
45%
36%
43%
80%
83% (75%)b
82%
45%
0
7
8c
9c
10c
11c
12c
13c
14c
15c,d
16c,d
17c,e
80 ꢀ
C
90 ꢀC
110 ꢀC
110 ꢀC
110 ꢀC
110 ꢀC
DMA
DMA
DMA
a
The reaction was run in 0.1 mmol scale, GC yield with C14H30 as internal
standard.
b
c
Isolated yield.
CaCO3 (3 equiv).
No Pd (OAc)2.
d
e
TEMPO (1 equiv).
Fig. 1. The structure of ligand L1eL4.
A possible mechanism was shown in Scheme 2: the reaction was
initiated from decomposition of hypervalent iodine to form a tert-
butyl radical. Then following addition of radical to double bond
Based on the optimization condition in hand, the scope of
formed intermediate I, which was trapped by a benzenoid p-sys-
substrates was investigated as shown in Table 2. The effect of the
protecting group on the nitrogen atom was firstly probed. For the
substrate 1a bearing a methyl group on nitrogen atom, the reaction
proceeded smoothly to provide product 2a in good yield (entry 1).
In contrast, the substrates 1b and 1c with an electron-withdrawing
tem. It is worth noting that addition of bidental nitrogen ligand L3
was significantly helpful in this reaction.17 It is possible that the
radical intermediate stabilized by L3 had a long life time resulting
in full conversion. However, the detailed mechanism for this pro-
cess is unclear at this moment.

T. Wu et al. / Tetrahedron 68 (2012) 5229e5233
5231
Table 2
Organocatalyzed arylalkylationa
Entry
1
Substrate
Product
Yieldb
R¼Me 1a
3a
75%
2
3
Ts 1b
Ac 1c
3b
3c
0%
0%
Scheme 2. The proposed mechanism.
4
R¼F 1d
3d
71%
acrylamides. The addition of organocatalyst significantly improved
the reaction yield. The further studies on the understanding
mechanism and application are under progress.
5
6
7
8
9
10
11
12
13
Cl 1e
Br 1f
I 1g
NO2 1h
CF3 1i
CO2Me 1j
OCF3 1k
Me 1l
3e
3f
3g
3h
3i
3j
3k
3l
76%
66%
59%
0%
18%
47%
77%
86%
67%
4. Experimental section
4.1. General methods
OMe 1m
3m
All commercially available compounds were used as received.
1H, 13C, and 19F spectra were recorded on a Varian Mercury-
400 MHz (400 MHz for 1H; 376 MHz for 19F; 100 MHz for 13C) or
a Bucker Avance-300 MHz (300 MHz for 1H; 282 MHz for 19F;
75 MHz for 13C) spectrometer. CDCl3 was purchased from J&K. The
14
15
16
R¼Me 1n
Ph 1o
1p
3n
3o
3p
86%
64%
71%
chemical shifts (d) were given in parts per million relative to in-
ternal standard TMS (0 ppm for 1H), CDCl3 (77.0 ppm for 13C). Flash
column chromatography was performed on silica gel 60 (particle
size 200e400 mesh ASTM, purchased from Yantai, China) and
eluted with petroleum ether/ethyl acetate. Solvents were dried and
purified according to the procedure from ‘Purification of Laboratory
Chemicals book’. Ligands and palladium catalyst were purchased
from Aldrich or Alfa Aesar.
17
18
19
1q
1r
1s
3q
3r
78%
69%
4.2. General procedure for aryalkylation of activated alkenes
(see Table 2)
In a TFE sealed dry glass tube, CsOPiv (146 mg, 0.6 mmol),
PhI(OOCtBu)2 (204 mg, 0.5 mmol), 2,9-dimethyl-1,10-
phenanthroline (6.4 mg, 0.03 mmol), CaCO3 (60 mg), and alkenes
1 (0.2 mmol) were dissolved in dry DMA (1.0 mL). The mixture was
stirred at 110 ꢀC for 24 h. Then ethyl acetate was added and the
mixture was filtered through a plug of Celite. The solvent was re-
moved under vacuum, and the residue was purified by column
chromatography on silica gel with a gradient eluant of petroleum
ether (or hexane) and ethyl acetate to afford the products 3. The
results were summarized in Table 2.
3s 47% (1:1)
3s0
20
1t
3t
0
4.3. Characterization of products
4.3.1. 1,3-Dimethyl-3-neopentylindolin-2-one (Table 2, entry 1,
a
Reaction condition is same with entry 15 in Table 1 in 0.2 mmol scale.
Isolated yield.
3a). Yield 75%. 1H NMR (400 MHz, CDCl3)
d
7.26 (t, J¼8.8 Hz, 1H),
b
7.20 (d, J¼7.6 Hz, 1H), 7.03 (t, J¼7.6 Hz, 1H), 6.85 (d, J¼8.0 Hz, 1H),
3.22 (s, 3H), 2.15 (d, J¼14.4 Hz, 1H), 1.85 (d, J¼14.4 Hz, 1H), 1.29 (s,
3H), 0.60 (s, 9H). 13C NMR (100 MHz, CDCl3)
d 181.0, 142.7, 134.0,
3. Conclusion
127.4, 123.8, 121.9, 107.9, 50.6, 47.3, 31.7, 30.7, 28.2, 26.1. HRMS: m/z
(EI) calculated [Mþ]: 231.1623, measured: 231.1626.
In conclusion, we have developed a novel organocatalyzed
arylalkylation of activated alkenes, which is a decarboxylation of
hypervalent dicarboxylate iodide. This reaction represents an effi-
cient way to synthesize a variety of oxindoles from simple aryl
4.3.2. 5-Fluoro-1,3-dimethyl-3-neopentylindolin-2-one (Table 2, en-
try 4, 3d). Yield 71%. 1H NMR (400 MHz, CDCl3)
d
7.00e6.93 (m,
2H), 6.77 (dd, J¼8.1, 4.2 Hz, 1H), 3.22 (s, 3H), 2.16 (d, J¼14.4 Hz,

5232
T. Wu et al. / Tetrahedron 68 (2012) 5229e5233
1H), 1.83 (d, J¼14.4 Hz, 1H), 1.29 (s, 3H), 0.63 (s, 9H). 13C NMR
3H), 3.80 (s, 3H), 3.20 (s, 3H), 2.15 (d, J¼14.4 Hz, 1H), 1.83 (d,
J¼14.4 Hz, 1H), 1.29 (s, 3H), 0.63 (s, 9H). 13C NMR (100 MHz, CDCl3)
(100 MHz, CDCl3)
d
180.6, 159.1 (d, J¼238.7 Hz), 137.3 (d,
J¼275.9 Hz), 135.8, 113.7 (d, J¼23.1 Hz), 111.8 (d, J¼23.8 Hz), 108.4
d 180.6, 155.6, 136.4, 135.6, 111.6, 111.4, 108.2, 55.8, 50.7, 47.7, 31.7,
(d, J¼8.2 Hz), 50.7, 47.8, 31.7, 30.8, 28.2, 26.3. 19F NMR (376 MHz,
30.8, 28.3, 26.2. HRMS: m/z (ESI) calculated [MþH]: 262.1807,
CDCl3)
measured: 249.1530.
d
ꢁ121.4. HRMS: m/z (EI) calculated [Mþ]: 249.1529,
measured: 262.1809.
4.3.11. 1,3,7-Trimethyl-3-neopentylindolin-2-one (Table 2, entry 14,
4.3.3. 5-Chloro-1,3-dimethyl-3-neopentylindolin-2-one (Table 2, en-
3n). Yield 86%. 1H NMR (400 MHz, CDCl3)
d
7.02 (d, J¼7.2 Hz, 1H),
try 5, 3e). Yield 76%. 1H NMR (300 MHz, CDCl3)
d
7.24 (dd, J¼8.1,
6.97 (d, J¼7.2 Hz, 1H), 6.91 (t, J¼7.2 Hz, 1H), 3.50 (s, 3H), 2.60 (s, 3H),
2.14 (d, J¼14.3 Hz, 1H), 1.83 (d, J¼14.3 Hz, 1H), 1.27 (s, 3H), 0.61 (s,
2.1 Hz, 1H), 7.18 (d, J¼2.1 Hz, 1H), 6.79 (d, J¼8.4 Hz, 1H), 3.22 (s, 3H),
2.16 (d, J¼14.4 Hz, 1H), 1.84 (d, J¼14.4 Hz, 1H), 1.29 (s, 3H), 0.62 (s,
9H). 13C NMR (100 MHz, CDCl3)
d 181.7, 140.6, 134.7, 131.1, 121.8,
9H). 13C NMR (75 MHz, CDCl3)
d
180.3, 141.3, 135.9, 127.3, 124.2,
119.5, 50.9, 46.6, 31.7, 30.8, 29.5, 28.6, 19.1. HRMS: m/z (EI) calcu-
lated [Mþ]: 245.1780, measured: 245.1781.
108.9, 50.6, 47.6, 31.7, 30.8, 28.1, 26.3. HRMS: m/z (EI) calculated
[Mþ]: 265.1233, measured: 265.1234.
4.3.12. 1,3-Dimethyl-3-neopentyl-7-phenylindolin-2-one (Table 2,
4.3.4. 5-Bromo-1,3-dimethyl-3-neopentylindolin-2-one (Table 2, en-
entry 15, 3o). Yield 64%. 1H NMR (400 MHz, CDCl3)
d 7.48e7.30 (m,
try 6, 3f). Yield 66%. 1H NMR (400 MHz, CDCl3)
d
7.39 (d, J¼8.4 Hz,
5H), 7.19 (d, J¼6.8 Hz, 1H), 7.09e7.01 (m, 2H), 2.74 (s, 3H), 2.19 (d,
1H), 7.31 (s, 1H), 6.73 (d, J¼8.4 Hz, 1H), 3.20 (s, 3H), 2.15 (d,
J¼14.3 Hz, 1H), 1.89 (d, J¼14.3 Hz, 1H), 1.34 (s, 3H), 0.67 (s, 9H). 13C
J¼14.4 Hz, 1H), 1.83 (d, J¼14.4 Hz, 1H), 1.29 (s, 3H), 0.63 (s, 9H). 13C
NMR (100 MHz, CDCl3) d 181.9,139.8,139.1,135.0,130.4,130.0,127.7,
NMR (100 MHz, CDCl3)
d
180.3,141.9,136.4,130.3,127.0,114.7,109.4,
127.5, 125.4, 122.7, 121.2, 51.1, 46.6, 31.7, 30.8, 30.2, 28.4. HRMS: m/z
(EI) calculated [Mþ]: 307.1936, measured: 307.1938.
50.7, 47.6, 31.8, 30.8, 28.1, 26.3. HRMS: m/z (EI) calculated [Mþ]:
309.0728, measured: 309.0725.
4.3.13. 1,3,4,6-Tetramethyl-3-neopentylindolin-2-one (Table 2, entry
4.3.5. 5-Iodo-1,3-dimethyl-3-neopentylindolin-2-one (Table 2, entry
16, 3p). Yield 71%. 1H NMR (300 MHz, CDCl3)
d
6.63 (s, 1H), 6.53 (s,
1H), 3.19 (s, 3H), 2.35 (s, 3H), 2.08 (d, J¼3.6 Hz, 2H),1.34 (s, 3H), 0.64
(s, 9H). 13C NMR (75 MHz, CDCl3)
181.3, 143.0, 137.3, 134.4, 128.1,
7, 3g). Yield 59%. 1H NMR (400 MHz, CDCl3)
d
7.57 (d, J¼8.0 Hz, 1H),
7.48 (s, 1H), 6.63 (d, J¼8.0 Hz, 1H), 3.20 (s, 3H), 2.14 (d, J¼14.4 Hz,
d
1H), 1.82 (d, J¼14.4 Hz, 1H), 1.28 (s, 3H), 0.62 (s, 9H). 13C NMR
125.4, 106.7, 49.0, 47.8, 31.6, 29.9, 26.2, 25.3, 21.5, 18.6. HRMS: m/z
(EI) calculated [Mþ]: 259.1936, measured: 259.1932.
(100 MHz, CDCl3) d 180.1, 142.5, 136.7, 136.3, 132.6, 110.0, 84.5, 50.7,
47.4, 31.7, 30.8, 28.1, 26.2. HRMS: m/z (EI) calculated [Mþ]:
357.0590, measured: 357.0591.
4.3.14. 1,3,5,7-Tetramethyl-3-neopentylindolin-2-one (Table 2, entry
17, 3q). Yield 78%. 1H NMR (300 MHz, CDCl3)
d 6.84 (s, 1H), 6.79 (s,
4.3.6. 1,3-Dimethyl-3-neopentyl-5-(trifluoromethyl)indolin-2-one
1H), 3.48 (s, 3H), 2.55 (s, 3H), 2.28 (s, 3H), 2.12 (d, J¼14.3 Hz, 1H),
(Table 2, entry 9, 3i). Yield 18%. 1H NMR (400 MHz, CDCl3)
d 7.12 (d,
1.79 (d, J¼14.3 Hz, 1H), 1.26 (s, 3H), 0.62 (s, 9H). 13C NMR (75 MHz,
J¼8.4 Hz, 1H), 7.09 (s, 1H), 6.83 (d, J¼8.4 Hz, 1H), 3.23 (s, 3H), 2.18 (d,
CDCl3) d 181.7, 138.2, 134.9, 131.6, 131.1, 122.5, 119.2, 50.9, 46.7, 31.7,
J¼14.4 Hz, 1H), 1.85 (d, J¼14.4 Hz,1H),1.31 (s, 3H), 0.61 (s, 9H).13C NMR
30.8, 29.5, 28.7, 20.8, 18.9. HRMS: m/z (EI) calculated [Mþ]:
(100 MHz, CDCl3)
d
180.7, 141.5, 135.7, 120.8, 117.9, 108.3, 50.8, 47.7, 31.8,
259.1936, measured: 259.1935.
30.8, 30.7, 28.1, 28.0, 26.4. 19F NMR (376 MHz, CDCl3, ppm)
d
ꢁ58.4.
HRMS: m/z (EI) calculated [Mþ]: 299.1497, measured: 299.1498.
4.3.15. 1,3,6,7-Tetramethyl-3-neopentylindolin-2-one (Table 2, entry
18, 3r). Yield 69%. 1H NMR (300 MHz, CDCl3)
d
6.92 (d, J¼9.6 Hz,
4.3.7. Methyl 1,3-dimethyl-3-neopentyl-2-oxoindoline-5-carboxylate
1H), 6.84 (d, J¼9.6 Hz, 1H), 3.52 (s, 3H), 2.49 (s, 3H), 2.31 (s, 3H),
2.13 (d, J¼14.3 Hz, 1H), 1.80 (d, J¼14.3 Hz, 1H), 1.25 (s, 3H), 0.61
(Table 2, entry 10, 3j). Yield 47%. 1H NMR (400 MHz, CDCl3)
d 8.03
(d, J¼8.8 Hz,1H), 7.89 (s,1H), 6.90 (d, J¼8.0 Hz,1H), 3.92 (s, 3H), 3.27
(s, 9H). 13C NMR (75 MHz, CDCl3)
d 182.2, 140.8, 137.0, 132.5,
(s, 3H), 2.17 (d, J¼14.4 Hz, 1H), 1.93 (d, J¼14.4 Hz, 1H), 1.32 (s, 3H),
123.5, 121.0, 118.7, 50.8, 46.3, 31.7, 30.7, 30.4, 28.7, 20.8, 14.1.
HRMS: m/z (EI) calculated [Mþ]: 259.1936, measured: 259.1934.
0.61 (s, 9H). 13C NMR (100 MHz, CDCl3)
d
176.6, 162.4, 142.4, 129.6,
125.7, 120.4, 119.3, 102.9, 47.4, 46.1, 42.6, 27.2, 26.2, 23.5, 21.8.
HRMS: m/z (EI) calculated [Mþ]: 289.1678, measured: 289.1674.
4.3.16. 5,7-Dimethyl-7-neopentyl-5H-[1,3]dioxolo[4,5-f]indol-6(7H)-
one
7(8H)-one (Table 2, entry 19, 3s and 3s0). Yield 47% (1:1). Com-
pound 3s 1H NMR (400 MHz, CDCl3)
6.73 (s, 1H), 6.48 (s, 1H),
and
6,8-dimethyl-6-neopentyl-6H-[1,3]dioxolo[4,5-g]indol-
4.3.8. 1,3-Dimethyl-3-neopentyl-5-(trifluoromethoxy)indolin-2-one
(Table 2, entry 11, 3k). Yield 77%. 1H NMR (300 MHz, CDCl3)
d
7.14
d
(d, J¼8.1 Hz, 1H), 7.10 (s, 1H), 6.84 (d, J¼8.4 Hz, 1H), 3.23 (s, 3H), 2.18
5.93 (d, J¼8.8 Hz, 2H), 3.18 (s, 3H), 2.12 (d, J¼14.0 Hz, 1H), 1.77 (d,
(d, J¼14.4 Hz, 1H), 1.86 (d, J¼14.5 Hz, 1H), 1.31 (s, 3H), 0.61 (s, 9H).
J¼14.0 Hz, 1H), 1.25 (s, 3H), 0.64 (s, 9H). 13C NMR (100 MHz,
13C NMR (75 MHz, CDCl3)
d
180.6, 144.4, 144.3, 141.4, 135.6, 120.7,
CDCl3) d 181.5, 147.2, 144.3, 143.1, 137.2, 115.7, 105.7, 101.2, 92.3,
117.9, 108.2, 50.7, 47.6, 31.7, 30.7, 28.0, 26.3. 19F NMR (376 MHz,
CDCl3)
51.0, 48.0, 32.0, 31.1, 28.6, 26.7. HRMS: m/z (ESI) calculated
d
ꢁ58.8. HRMS: m/z (EI) calculated [Mþ]: 315.1446, mea-
[MþNa]: 298.1419, measured: 298. 1421. Compound 3s0 1H NMR
sured: 315.1442.
(400 MHz, CDCl3)
d
6.71 (d, J¼7.6 Hz, 1H), 6.27 (d, J¼7.6 Hz, 1H),
5.95 (d, J¼8.8 Hz, 2H), 3.18 (s, 3H), 2.09 (d, J¼14.4 Hz, 1H), 1.97 (d,
4.3.9. 1,3,5-Trimethyl-3-neopentylindolin-2-one (Table 2, entry 12,
J¼14.0 Hz, 1H), 1.37 (s, 3H), 0.65 (s, 9H). 13C NMR (100 MHz,
3l). Yield 86%. 1H NMR (300 MHz, CDCl3)
d
7.05 (d, J¼10.8 Hz, 1H),
CDCl3) d 180.3, 144.3, 143.1, 137.2, 115.7, 105.7, 101.2, 92.3, 49.6,
7.02 (s, 1H), 6.74 (d, J¼11.2 Hz, 1H), 3.20 (s, 3H), 2.34 (s, 3H), 2.14 (d,
46.8, 31.8, 30.3, 27.3, 26.3. HRMS: m/z (ESI) calculated [MþH]:
J¼14.3 Hz, 1H), 1.84 (d, J¼14.4 Hz, 1H), 1.28 (s, 3H), 0.61 (s, 9H). 13C
276.1600, measured: 276.1602.
NMR (75 MHz, CDCl3)
d 181.0, 134.2, 131.4, 127.7, 124.7, 107.7, 50.7,
47.4, 31.7, 30.8, 28.3, 26.2, 21.2. HRMS: m/z (EI) calculated [Mþ]:
Acknowledgements
245.1780, measured: 245.1781.
We thank 973 program of China (2009CB825300), NSFC
(20972175 and 21121062), and STCSM(11JC1415000) for financial
support.
4.3.10. 5-Methoxy-1,3-dimethyl-3-neopentylindolin-2-one (Table 2,
entry 13, 3m). Yield 67%. 1H NMR (400 MHz, CDCl3)
d 6.83e6.74 (m,

T. Wu et al. / Tetrahedron 68 (2012) 5229e5233
5233
9. Sun, C.-L.; LI, H.; Yu, D.-G.; Yu, M.; Zhou, X.; Lu, X.-Y.; Huang, K.; Zheng, S. F.; Li,
B.-J.; Shi, Z.-J. Nat. Chem. 2010, 2, 1044.
Supplementary data
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Supplementary data related to this article can be found online at
doi:10.1016/j.tet.2012.03.051.
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