Metal-free direct trifluoromethylation of activated alkenes with Langlois' reagent leading to CF3-containing oxindoles

Article abstract of DOI:10.1021/jo500515x

A metal-free and cost-effective synthesis protocol has been initially proposed for the construction of CF₃-containing oxindoles via the direct oxidative trifluoromethylation of activated alkenes with Langlois' reagent (CF₃SO₂Na). The present methodology, which utilizes very cheap CF₃ reagent and a simple oxidant, provides a convenient and practical approach to CF₃-containing oxindoles with a wide variety of functional groups.

Full text of DOI:10.1021/jo500515x

Note
pubs.acs.org/joc
Metal-Free Direct Trifluoromethylation of Activated Alkenes with
Langlois’ Reagent Leading to CF3‑Containing Oxindoles
Wei Wei, Jiangwei Wen, Daoshan Yang, Xiaoxia Liu, Mengyuan Guo, Ruimei Dong, and Hua Wang*
The Key Laboratory of Life-Organic Analysis and Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine,
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, Shandong China
S
* Supporting Information
ABSTRACT: A metal-free and cost-effective synthesis proto-
col has been initially proposed for the construction of CF3-
containing oxindoles via the direct oxidative trifluoromethyla-
tion of activated alkenes with Langlois’ reagent (CF3SO2Na).
The present methodology, which utilizes very cheap CF3
reagent and a simple oxidant, provides a convenient and
practical approach to CF3-containing oxindoles with a wide
variety of functional groups.
he incorporation of a CF3 group into organic molecules of
pharmacological relevance is of great interest in organic
with CF3SO2Na for the synthesis of α-CF3-substituted
ketones.12 Very recently, Lipshutz and Liang reported Cu-
(NO3)2 (10 mol %) catalyzed trifluoromethylation of N-
arylacrylamides with CF3SO2Na leading to oxindoles in the
presence of 3.5 equiv of TBHP.13 However, a toxic transition-
metal catalytic system was still involved in these methods that
have introduced CF3SO2Na as the CF3. In 2011, Baran et al.
described an efficient trifluoromethylation reaction of hetero-
cycles with CF3SO2Na in the presence of excess amounts of
TBHP (5−10 equiv).14 In this paper, we report an efficient,
cost-effective, and metal-free protocol for the direct oxidative
trifluoromethylation of activated alkenes toward a variety of
CF3-containing oxindoles by using very cheapest CF3SO2Na as
the CF3 source and K2S2O8 as the oxidant (Scheme 1). The
protocol complements the methods of Lipschutz et al. and
Baran et al. but avoids the use of copper catalysts and TBHP.
In an initial experiment, N-arylacrylamide 1a was treated with
CF3SO2Na in the presence of 1 equiv of Na2S2O8 in CH3CN/
T
and medicinal chemistry because it could significantly enhance
their chemical and metabolic stability, electronegativity, lip-
ophilicity, and binding selectivity.1,2 Over the past several years,
a number of synthesis methods for introducing a CF3 moiety
into common synthetic scaffolds have been developed.3 In
particular, the synthesis of a CF3-containing oxindoles has
recently drawn increasing attention from chemists, owing to
their importance for both pharmaceutical and synthetic
research.4−7 For example, in 2012, Liu’s group reported the
palladium-/ytterbium-catalyzed oxidative aryltrifluoromethyla-
tion reaction of activated alkenes for the synthesis of CF3-
containing oxindoles by using combination of the TMSCF3/
CsF/PhI(OAc)2.4 Sodeoka and Zhu proposed a complemen-
tary method for copper- or ruthenium-catalyzed aryltrifluor-
omethylation of simple alkenes with expensive Togni’s
reagent.5,6 Very recently, Nevado and co-workers also described
the copper- and tetrabutylammonium iodide-catalyzed aryltri-
fluoromethylation of activated alkenes by employing Togni’s
reagent as the CF3 source.7 Nevertheless, these well-established
trifluoromethylation reactions usually require toxic transition-
metal catalysts, expensive CF3 reagents, and relatively complex
reaction conditions, which have limited their wide applications
in the field of synthetic chemistry and pharmaceutical industry.
Therefore, there is still a great demand for the development of
simple, convenient, economic, and metal-free trifluoromethyla-
tion strategies to construct CF3-substituted oxindoles.
Scheme 1. Trifluoromethylation Reactions with Langlois’
Reagent (CF3SO2Na)
Recently, Langlois’ reagent (CF3SO2Na), a cheap and stable
solid CF3 source, has emerged for the construction of CF3-
containing organic compounds via C−C bond formation.8−13
Several studies have shown that the trifluoromethylations of
heterocycles,8 aryl boronic acids,9 α,β-unsaturated carboxylic
acids,10 and unsaturated organotrifluoroborates11 could be
achieved by the combination of CF3SO2Na and Cu/TBHP
catalytic systems. In 2013, Maiti et al. demonstrated the AgNO3
(20 mol %) catalyzed oxidative trifluoromethylation of olefins
Received: March 4, 2014
Published: April 1, 2014
© 2014 American Chemical Society
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Note
H2O (4:1) at 80 °C (Table 1, entry 1). Gratifyingly, the desired
trifluoromethylated product 3a was obtained in 18% yield.
With the optimized conditions in hand, the scope and
limitations of this reaction were investigated. As shown in Table
2, the effect of N-protecting groups on the reactions was first
a
Table 1. Optimization of the Reaction Conditions
Table 2. Trifluoromethylation of Different Activated Alkenes
a,b
with CF3SO2Na
b
entry
oxidant (equiv)
solvent
yield (%)
1
Na2S2O8 (1)
K2S2O8 (1)
(NH4)2S2O8 (1)
TBHP (1)
DTBP (1)
H2O2 (1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
DME/H2O (4/1)
DMSO/H2O (4/1)
DMF/H2O (4/1)
1,4-dioxane/H2O (4/1)
DMA/H2O (4/1)
DCE/H2O (4/1)
CH3CN/H2O (2/1)
CH3CN/H2O (2/1.5)
CH3CN/H2O (1/1)
CH3CN
18
2
33
3
20
4
10
5
n.r.
trace
trace
65
6
7
PhI(OAc)2 (1)
K2S2O8 (1.5)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
K2S2O8 (2)
none
8
9
88
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
39
35
45
50
65
trace
49
29
26
35
H2O
49
c
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
CH3CN/H2O (4/1)
Trace
d
61
e
77
n.r
a
Reaction conditions: N-arylacrylamide 1a (0.25 mmol), CF3SO2Na 2
(0.75 mmol), oxidant (1−2 equiv), solvent (2.5 mL), 80 °C, 12 h,
under N2. n.r. = no reaction. TBHP: tert-butyl hydroperoxide, 70%
b
solution in water; DTBP: di-tert-butyl peroxide. Isolated yields based
c
d
e
on 1a. 25 °C. 60 °C. 100 °C.
Encouraged by this result, we further optimized the reaction
conditions by changing the oxidants. The investigation results
showed that using K2S2O8 (1 equiv) as an oxidant herein gave
the best yield (33%), whereas other oxidants such as
(NH4)2S2O8, TBHP, DTBP, H2O2, and PhI(OAc)2 did not
or only sluggishly promoted this reaction (Table 1, entries 3−
7). We were pleased to find that increasing the amount of
K2S2O8 up to 2 equiv could improve the yield to 88% (Table 1,
entries 8 and 9). The screening of a range of solvents revealed
that the reaction performed in CH3CN/H2O (4:1) was
significantly better than others (Table 1, entries 9−18). In
contrast, product 3a was isolated in low yield when the reaction
was performed in the absence of H2O or CH3CN (Table 1,
entries 19 and 20). This reaction is a heterogeneous reaction
system; a small amount of water existing in this reaction system
would improve the solubility of inorganic salts CF3SO2Na and
K2S2O8, but this reaction might be suppressed with the excess
amount of water. As a result, higher yield of product might be
obtained in MeCN/water (4:1) system. In addition, the best
yield of 3a was obtained when the reaction was performed at 80
°C (Table 1, entries 9 and 21−23). No conversion was
observed in the absence of oxidant (Table 1, entry 24).
a
Reaction conditions: N-arylacrylamide 1 (0.25 mmol), CF3SO2Na 2
(0.75 mmol), K2S2O8 (2 equiv), CH3CN/H2O (2.5 mL, 4/1), 80 °C,
b
12−36 h, under N2. Isolated yields based on 1.
screened, and the results showed that substrates bearing alkyl
and aryl protecting groups on the nitrogen are suitable for this
reaction (2a,b), whereas N-free and acetyl N-arylacrylamides
failed to give the desired products. Meanwhile, N-arylacryla-
mides with various substitution patterns at the aniline moieties
were examined. In general, the substrates bearing electron-
donating or electron-withdrawing substituents on the aniline
moieties were suitable for this reaction, and the desired
products were obtained in good yields (3d−l). It is noteworthy
that various substituted functional groups such as F, Cl, Br,
cyano, and carbonyl groups were compatible with this process
to afford the corresponding oxindoles (3g−k), which could be
used for further modifications at the substituted positions. The
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sterically congested ortho-substituted substrate was also
effectively reacted with CF3SO2Na to give product 3m in
90% yields. Substituent groups at the meta-position of the
phenyl ring afforded a mixture of two regioselective products
(products 3n and 3n′). Notably, the cyclization of indoline and
tetrahydroquinoline derivatives could afford tricyclic oxindoles
3o and 3p in 45% and 79% yields, respectively. Finally, the
substrates bearing different substituents on olefin were
evaluated. A variety of α-substituted alkenes with different
functional groups such as aryl, benzyl, alcohol, and ester were
well tolerated to this reaction, affording the desired products
3q−t in moderate to good yields.
EXPERIMENTAL SECTION
■
General Methods. Chemicals were commercially available and
were used without further purification unless otherwise stated. All
solvents were dried according to standard procedures. 1H, 13C, and 19
F
NMR spectra were obtained in CDCl3 with TMS as internal standard
(400 MHz 1H, 100 MHz 13C, 376 MHz 19F) at room temperature, the
chemical shifts (δ) are expressed in ppm, and J values are given in
hertz. The following abbreviations are used to indicate the multiplicity:
singlet (s), doublet (d), triplet (t), quartet (q), doublet of doublets
(dd), doublet of triplets (dt), doublet of quartets (dq), and multiplet
(m). All first-order splitting patterns were assigned on the basis of the
appearance of the multiplet. Splitting patterns that could not be easily
interpreted were designated as multiplet (m). HRMS data were
obtained by ESI on a TOF mass analyzer. Column chromatography
was performed on silica gel (200−300 mesh). N-Arylacrylamides 1
were prepared according to previous literatures.17,18 Substrates 1q and
1r were prepared according to the literature.18,19 Substrate 1s and 1t
were prepared according to the literature.17
It is known that CF3SO2Na can be easily transformed to CF3
radical in the presence of a transition-metal catalytic oxidation
system,8−14 which implies that this reaction might also proceed
through a radical process. As shown in Scheme 2, when
General Experimental Procedures. To a mixture of N-
arylacrylamide 1 (0.25 mmol), CF3SO2Na 2 (0.75 mmol), and
K2S2O8 (0.5 mmol) in a 25 mL round-bottomed flack at room
temperature under N2 (balloon) was added CH3CN/H2O (4/1, 2.5
mL). The reaction vessel was allowed to stir at 80 °C for 12−36 h.
After the reaction, the resulting mixture was extracted with EtOAc.
The combined organic phase was dried over anhydrous Na2SO4, and
the solvent was then removed under vacuum. The residue was purified
by flash column chromatography using a mixture of petroleum ether
and ethyl acetate as eluent to give the desired product 3.
Scheme 2. Radical Trapping Experiment
TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy, a well-known
radical-capturing species) was added to the present reaction
system, the trifluoromethylation reaction was completely
suppressed. This result suggested that the reaction should
proceed through a radical pathway.
Based on the above experimental results and previous reports
about oxindole synthesis,15,16 a postulated reaction pathway
was thereby proposed as shown in Scheme 3. Initially,
Experimental Procedure for Preliminary Mechanistic Stud-
ies with TEMPO. To a mixture of N-arylacrylamide 1a (0.25 mmol),
CF3SO2Na (0.75 mmol), TEMPO (0.5 mmol), and K2S2O8 (0.5
mmol) was added CH3CN/H2O (4/1) 2.5 mL at room temperature
under N2 (balloon). The reaction vessel was allowed to stir for 12 h at
80 °C. After the reaction, the solution was concentrated in vacuum,
and no desired product was detected.
1,3-Dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3a).4,13 Com-
pound 3a was obtained in 88% yield (53.5 mg) according to the
Scheme 3. Postulated Reaction Pathway
1
general procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.34
(dt, J1 = 1.0 Hz, J2 = 7.7 Hz, 1H), 7.29 (d, J = 7.2 Hz, 1H), 7.12 (t, J =
7.6 Hz, 1H), 6.91 (d, J = 7.8 Hz, 1H), 3.26 (s, 3H), 2.84 (dq, J1 = 10.7
Hz, J2 = 15.2 Hz, 1H), 2.67 (dq, J1 = 10.5 Hz, J2 = 15.2 Hz, 1H), 1.43
(s, 3H); 13C NMR (CDCl3, 100 MHz, ppm) δ 178.5, 142.9, 131.0,
128.5, 125.3 (q, J = 276 Hz), 123.5 (q, J = 2 Hz), 122.7, 108.5, 44.4 (d,
J = 2 Hz), 40.6 (q, J = 27 Hz), 26.4, 25.0; 19F NMR (376 MHz,
CDCl3) δ −61.9; HRMS calcd for C12H12F3NONa (M + Na)+
266.0769, found 266.0770.
3-Methyl-1-phenyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3b).4,13
Compound 3b was obtained in 73% yield (56 mg) according to the
1
general procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.55
(t, J = 7.4 Hz, 2H), 7.47−7.41 (m, 3H), 7.34 (d, J = 7.4 Hz, 1H), 7.25
(dd, J1 = 1.2 Hz, J2 = 7.8 Hz, 1H), 7.15 (dt, J1 = 1.0 Hz, J2 = 7.5 Hz,
1H), 6.86 (d, J = 7.9 Hz, 1H), 2.99 (dq, J1 = 10.7 Hz, J2 = 15.1 Hz,
1H), 2.75 (dq, J1 = 10.4 Hz, J2 = 15.1 Hz, 1H), 1.56 (s, 3H); 13C NMR
(CDCl3, 100 MHz, ppm) δ 177.9, 143.0, 134.4, 130.7, 129.7, 128.4,
128.2, 126.6, 125.3 (q, J = 278 Hz), 123.8 (q, J = 1.3 Hz), 123.1, 109.8,
44.5 (d, J = 2 Hz), 41.1 (q, J = 27 Hz), 25.4; 19F NMR (376 MHz,
CDCl3) δ −61.9; HRMS calcd for C17H14F3NONa (M + Na)+
328.0925, found 328.0925.
CF3SO2Na was converted into the CF3 radical in the presence
of K2S2O8. Subsequently, the CF3 radical selectively added to
the carbon−carbon double bond of N-arylacrylamide 1a leading
to alkyl radical 4a, which underwent an intramolecular radical
cyclization to generate intermediate 5a. Finally, oxidation of 5a
afforded the corresponding carbocation, followed by the loss of
H+, thus producing the CF3-substituted oxindole 3a.
In summary, we have developed a new metal-free synthesis
strategy for the direct oxidative trifluoromethylation of
activated alkenes toward the CF3-containing oxindoles by
using CF3SO2Na as the CF3 source and K2S2O8 as the oxidant.
Such a green protocol, which utilizes metal-free reaction
conditions, cheap CF3 reagents, and cost-effective oxidants,
provides a practical and efficient approach to various CF3-
containing oxindoles. It would extend the potential applications
of CF3-containing oxindoles bearing a quaternary carbon center
in pharmaceutical and synthetic chemistry.
1,3,5-Trimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3d).4,13
Compound 3d was obtained in 89% yield (57 mg) according to the
1
general procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.13
(d, J = 8.1 Hz, 1H), 7.10 (s, 1H), 6.79 (d, J = 7.8 Hz, 1H), 3.23 (s,
3H), 2.82 (dq, J1 = 10.8 Hz, J2 = 15.2 Hz, 1H), 2.65 (dq, J1 = 10.6 Hz,
J2 = 15.2 Hz, 1H), 2.37 (s, 3H), 1.41 (s, 3H); 13C NMR (CDCl3, 100
MHz, ppm) δ 178.4, 140.5, 132.2, 131.1, 128.8, 125.3 (q, J = 276 Hz),
124.3 (q, J = 2 Hz), 108.2, 44.4 (d, J = 2 Hz), 40.6 (q, J = 28 Hz), 26.4,
25.0, 21.1; 19F NMR (376 MHz, CDCl3) δ −61.9; HRMS calcd for
C13H14F3NONa (M + Na)+ 280.0925, found 280.0931.
5-Methoxy-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one
(3e).4,13 Compound 3e was obtained in 88% yield (60 mg) according
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Note
to the general procedure (36 h): 1H NMR (CDCl3, 400 MHz, ppm) δ
6.90 (d, J = 2.4 Hz, 1H), 6.85 (dd, J1 = 2.5 Hz, J2 = 8.5 Hz,1H), 6.79
(d, J = 2.4 Hz, 1H), 3.82 (s, 3H), 3.23 (s, 3H), 2.83 (dq, J1 = 10.8 Hz,
J2 = 15.2 Hz, 1H), 2.64 (dq, J1 = 10.5 Hz, J2 = 15.2 Hz, 1H), 1.41 (s,
3H); 13C NMR (CDCl3, 100 MHz, ppm) δ 178.1, 156.1, 136.3, 132.4,
125.2 (q, J = 281 Hz), 112.6, 111.2 (q, J = 1.3 Hz), 108.7, 55.8, 44.8
(q, J = 2 Hz), 40.5 (q, J = 28 Hz), 26.5, 25.0; 19F NMR (376 MHz,
CDCl3) δ −61.9; HRMS calcd for C13H14F3NO2Na (M + Na)+
296.0874, found 296.0873.
125.1 (q, J = 272 Hz), 123.4 (q, J = 1.3 Hz), 108.0, 44.2 (d, J = 3 Hz),
40.6 (q, J = 28 Hz), 26.7, 26.3, 25.0; 19F NMR (376 MHz, CDCl3) δ
−62.1; HRMS calcd for C14H14F3NO2Na (M + Na)+ 308.0874, found
308.0874.
1,3-Dimethyl-3-(2,2,2-trifluoroethyl)-5-(trifluoromethyl)indolin-2-
one (3l).13 Compound 3l was obtained in 94% yield (73 mg)
1
according to the general procedure (12 h): H NMR (CDCl3, 400
MHz, ppm) δ 7.62 (dd, J1 = 0.8 Hz, J2 = 7.4 Hz, 1H), 7.52 (s, 1H),
6.98 (d, J = 8.2 Hz, 1H), 3.30 (s, 3H), 2.89 (dq, J1 = 10.6 Hz, J2 = 15.2
Hz, 1H), 2.71 (dq, J1 = 10.4 Hz, J2 = 15.2 Hz, 1H), 1.46 (s, 3H); 13
C
5-Butyl-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3f).
NMR (CDCl3, 100 MHz, ppm) δ 178.3, 145.9, 131.6, 126.4 (q, J = 4.0
Hz), 125.6, 125.2, 124.9, 123.6, 122.9, 120.7 (q, J = 2 Hz), 108.3, 44.3
(d, J = 2 Hz), 40.6 (q, J = 28 Hz), 26.6, 24.9; 19F NMR (376 MHz,
CDCl3) δ −61.6, −62.1; HRMS calcd for C13H11F6NONa (M + Na)+
334.0643, found 334.0642.
Compound 3f was obtained in 93% yield (69.5 mg) according to
the general procedure (24 h): H NMR (CDCl3, 400 MHz, ppm) δ
1
7.13 (dd, J1 = 1.6 Hz, J2 = 6.3 Hz, 1H), 7.11 (s, 1H), 6.81 (d, J = 8.0
Hz, 1H), 3.24 (s, 3H), 2.83 (dq, J1 = 10.8 Hz, J2 = 15.2 Hz, 1H), 2.69−
2.60 (m, 3H), 1.64−1.56 (m, 2H), 1.42 (s, 3H), 1.36 (q, J = 7.4 Hz,
2H), 0.94 (t, J = 7.4 Hz, 3H); 13C NMR (CDCl3, 100 MHz, ppm) δ
178.5, 140.6, 137.5, 131.0, 128.2, 125.3 (q, J = 280 Hz), 123.8 (q, J = 2
Hz), 108.1, 44.5 (d, J = 2 Hz), 40.6 (q, J = 28 Hz); 35.4, 34.0, 26.5,
25.0, 22.3, 13.9; 19F NMR (376 MHz, CDCl3) δ −61.9; HRMS calcd
for C16H20F3NONa (M + Na)+ 322.1395, found 322.1392.
5-Fluoro-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one
(3g).4,13 Compound 3g was obtained in 92% yield (60 mg) according
to the general procedure (12 h): 1H NMR (CDCl3, 400 MHz, ppm) δ
7.06−7.01 (m, 2H), 6.82 (dd, J1 = 4.2 Hz, J2 = 9.2 Hz, 1H), 3.25 (s,
3H), 2.84 (dq, J1 = 10.7 Hz, J2 = 15.2 Hz, 1H), 2.65 (dq, J1 = 10.4 Hz,
J2 = 15.2 Hz, 1H), 1.43 (s, 3H); 13C NMR (CDCl3, 100 MHz, ppm) δ
178.1, 159.3 (d, J = 240 Hz), 138.8 (d, J = 2 Hz), 132.6 (d, J = 8 Hz),
125.1 (q, J = 276 Hz), 114.8 (d, J = 23 Hz), 111.9 (q, J = 2 Hz), 111.6
(q, J = 2 Hz), 108.9 (d, J = 8 Hz), 44.8 (d, J = 2 Hz), 40.6 (q, J = 28
Hz), 26.6, 24.9; 19F NMR (376 MHz, CDCl3) δ −62.0, −120.3;
HRMS calcd for C12H11F4NONa (M + Na)+ 284.0674, found
284.0671.
1,3,7-Trimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3m). Com-
pound 3m was obtained in 90% yield (58 mg) according to the general
1
procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.10 (d, J =
7.5 Hz, 1H), 7.06 (d, J = 7.7 Hz, 1H), 7.98 (t, J = 7.4 Hz, 1H), 3.54 (s,
3H), 2.86 (dq, J1 = 10.7 Hz, J2 = 15.2 Hz, 1H), 2.65 (dq, J1 = 10.5 Hz,
J2 = 15.2 Hz, 1H), 2.62 (s, 3H), 1.40 (s, 3H); 13C NMR (CDCl3, 100
MHz, ppm) δ 179.4, 140.7, 132.1, 131.6, 125.2 (q, J = 287 Hz), 122.5,
121.4 (d, J = 1 Hz), 120.0, 43.7 (q, J = 2 Hz), 40.9 (q, J = 22 Hz), 29.8,
25.5, 19.0; 19F NMR (376 MHz, CDCl3) δ −61.9; HRMS calcd for
C13H14NOF3Na (M + Na)+ 280.0925, found 280.0926.
1,3-Dimethyl-4-nitro-3-(2,2,2-trifluoroethyl)indolin-2-one (3n)
and 1,3-Dimethyl-6-nitro-3-(2,2,2-trifluoroethyl)indolin-2-one
(3n′).4 Compounds 3n and 3n′ were obtained in 70% total yield
(50.5 mg) according to the general procedure (12 h): 1H NMR
(CDCl3, 400 MHz, ppm) δ 8.02 (dd, J1 = 2.1 Hz, J2 = 8.2 Hz, 0.8H),
7.93 (dd, J1 = 1.0 Hz, J2 = 8.5 Hz, 1H), 7.74 (d, J = 2.0 Hz, 0.8H), 7.54
(t, J = 7.9 Hz, 1H), 7.43 (d, J = 8.2 Hz, 0.8H), 7.23 (dd, J1 = 0.8 Hz, J2
= 7.8 Hz, 1H), 3.38 (dq, J1 = 10.6 Hz, J2 = 15.2 Hz, 1H), 3.33 (s,
2.4H), 3.32 (s, 3H), 3.04−2.89 (m, 1.8H), 2.72 (dq, J1 = 10.3 Hz, J2 =
15.2 Hz, 0.8H), 1.61 (s, 3H), 1.47 (s, 2.4H); 13C NMR (CDCl3, 100
MHz, ppm) δ 178.1, 177.8, 148.7, 146.1, 145.6, 144.2, 137.9, 125.6,
125.2 (q, J = 276 Hz), 124.9 (q, J = 276 Hz), 124.0 (q, J = 1.3 Hz),
118.6, 118.2, 114.0, 103.5, 44.6 (d, J = 3 Hz), 44.5 (d, J = 2 Hz), 40.5
(q, J = 28 Hz), 38.6 (q, J = 28 Hz), 27.1, 26.8, 24.8, 22.9; 19F NMR
(376 MHz, CDCl3) δ −62.0, −64.4.
5-Chloro-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one
(3h).4,13 Compound 3h was obtained in 94% yield (65 mg) according
to the general procedure (12 h): 1H NMR (CDCl3, 400 MHz, ppm) δ
7.30 (dd, J1 = 2.1 Hz, J2 = 6.2 Hz, 1H), 7.26 (d, J = 1.8 Hz, 1H), 6.82
(d, J = 8.3 Hz, 1H), 3.24 (s, 3H), 2.86 (dq, J1 = 10.7 Hz, J2 = 15.2 Hz,
1H), 2.65 (dq, J1 = 10.4 Hz, J2 = 15.2 Hz, 1H), 1.42 (s, 3H); 13C NMR
(CDCl3, 100 MHz, ppm) δ 177.9, 141.5, 132.7, 128.5, 128.1, 125.6 (q,
J = 275 Hz), 124.1 (q, J = 1.3 Hz), 109.4, 44.6 (q, J = 2 Hz), 40.6 (q, J
= 28 Hz), 26.6, 24.9; 19F NMR (376 MHz, CDCl3) δ −62.0; HRMS
calcd for C12H11F3ClNONa (M + Na)+ 300.0379, found 300.0378.
5-Bromo-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one
(3i).4,13 Compound 3i was obtained in 85% yield (68 mg) according to
1,3-Dimethyl-4-nitro-3-(2,2,2-trifluoroethyl)indolin-2-one (3n):4
1H NMR (CDCl3, 400 MHz, ppm) 7.94 (dd, J1 = 1.0 Hz, J2 = 8.5
Hz, 1H), 7.54 (t, J = 7.9 Hz, 1H), 7.23 (dd, J1 = 0.8 Hz, J2 = 7.9 Hz,
1H), 3.39 (dq, J1 = 10.6 Hz, J2 = 15.2 Hz, 1H), 3.33 (s, 3H), 3.00 (dq,
J1 = 10.8 Hz, J2 = 15.2 Hz, 1H), 1.62 (s, 3H); HRMS calcd for
C12H11F3N2O3Na (M + Na)+ 311.0619, found 311.0619.
1
the general procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ
7.46 (dd, J1 = 1.9 Hz, J2 = 6.3 Hz, 1H), 7.39 (d, J = 1.8 Hz, 1H), 6.78
(d, J = 8.3 Hz, 1H), 3.24 (s, 3H), 2.85 (dq, J1 = 10.6 Hz, J2 = 15.2 Hz,
1H), 2.66 (dq, J1 = 10.4 Hz, J2 = 15.2 Hz, 1H), 1.42 (s, 3H); 13C NMR
(CDCl3, 100 MHz, ppm) δ 177.8, 142.0, 133.1, 131.4, 126.8 (q, J = 1.7
Hz), 125.1 (q, J = 277 Hz), 115.3, 109.9, 44.5 (d, J = 2 Hz), 40.3 (q, J
= 28 Hz), 26.6, 24.9; 19F NMR (376 MHz, CDCl3) δ −62.0; HRMS
calcd for C12H11F3BrNONa (M + Na)+ 343.9874, found 343.9875.
1,3-Dimethyl-2-oxo-3-(2,2,2-trifluoroethyl)indoline-5-carbonitrile
(3j).5b Compound 3j was obtained in 90% yield (60 mg) according to
1,3-Dimethyl-6-nitro-3-(2,2,2-trifluoroethyl)indolin-2-one (3n′):4
1H NMR (CDCl3, 400 MHz, ppm) δ 8.04 (dd, J1 = 2.1 Hz, J2 = 8.2
Hz, 1H), 7.75 (d, J = 2.1 Hz, 1H), 7.43 (d, J = 7.9 Hz, 1H), 3.35 (s,
3H), 2.94 (dq, J1 = 10.4 Hz, J2 = 15.2 Hz, 1H), 2.72 (dq, J1 = 10.4 Hz,
J2 = 15.2 Hz, 1H), 1.48 (s, 3H); HRMS calcd for C12H11F3N2O3Na
(M + Na)+ 311.0619, found 311.0618.
1-Methyl-1-(2,2,2-trifluoroethyl)-4,5-dihydropyrrolo[3,2,1-hi]-
indol-2(1H)-one (3o). Compound 3o was obtained in 45% yield (29
mg) according to the general procedure (30 h): 1H NMR (CDCl3, 400
MHz, ppm) δ 8.18 (d, J = 8.2 Hz, 1H), 7.25 (t, J = 7.0 Hz, 1H), 7.11
(t, J = 7.8 Hz, 1H), 4.56−4.45 (m, 2H), 3.64−3.52 (m, 1H), 3.22 (t, J
= 8.0 Hz, 2H), 3.16−3.04 (m, 1H), 2.24 (s, 3H); 13C NMR (CDCl3,
100 MHz, ppm) δ 166.2, 143.9, 131.2, 127.5, 124.8 (q, J = 286 Hz),
124.7, 124.5, 118.8, 54.5 (d, J = 2 Hz), 50.5, 46.5 (q, J = 28 Hz), 29.4,
28.5; 19F NMR (376 MHz, CDCl3) δ −59.9; HRMS calcd for
C13H12F3NONa (M + Na)+ 278.0769, found 278.0771.
1
the general procedure (12 h): H NMR (CDCl3, 400 MHz, ppm) δ
7.67 (dd, J1 = 1.6 Hz, J2 = 6.6 Hz, 1H), 7.54 (d, J = 1.2 Hz, 1H), 6.98
(d, J = 8.2 Hz, 1H), 3.29 (s, 3H), 2.88 (dq, J1 = 10.6 Hz, J2 = 15.3 Hz,
1H), 2.69 (dq, J1 = 10.3 Hz, J2 = 15.2 Hz, 1H), 1.45 (s, 3H); 13C NMR
(CDCl3, 100 MHz, ppm) δ 178.1, 146.7, 133.9, 132.0, 127.0 (J = 1.3
Hz), 124.9 (q, J = 276 Hz), 119.0, 109.0, 106.0, 44.2 (d, J = 2 Hz),
40.5 (q, J = 28 Hz), 26.7, 24.9; 19F NMR (376 MHz, CDCl3) δ −62.0;
HRMS calcd for C13H11F3N2ONa (M + Na)+ 291.0721, found
291.0723.
1-Methyl-1-(2,2,2-trifluoroethyl)-5,6-dihydro-1H-pyrrolo[3,2,1-ij]-
5-Acetyl-1,3-dimethyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3k).
quinolin-2(4H)-one (3p).4,13 Compound 3p was obtained in 79%
1
Compound 3k was obtained in 73% yield (52 mg) according to the
yield (53 mg) according to the general procedure (30 h): H NMR
1
general procedure (24 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.99
(CDCl3, 400 MHz, ppm) δ 7.13 (d, J = 7.4 Hz, 1H), 7.08 (d, J = 7.5
Hz, 1H), 6.99 (t, J = 7.5 Hz, 1H), 3.75 (t, J = 5.8 Hz, 2H), 2.84−2.61
(m, 4H), 2.07−2.01 (m, 2H), 1.44 (s, 3H); 13C NMR (CDCl3, 100
MHz, ppm) δ 177.3, 138.7, 129.7, 127.3, 125.4 (q, J = 278 Hz), 122.1,
121.5 (q, J = 2 Hz), 120.5, 45.7 (d, J = 2.0 Hz), 40.5 (q, J = 28 Hz),
(dd, J1 = 1.6 Hz, J2 = 8.2 Hz, 1H), 7.93 (s, 1H), 6.95 (d, J = 8.2 Hz,
1H), 3.30 (s, 3H), 2.88 (dq, J1 = 10.6 Hz, J2 = 15.2 Hz, 1H), 2.69 (dq,
J1 = 10.4 Hz, J2 = 15.2 Hz, 1H), 2.61(s, 3H), 1.45 (s, 3H); 13C NMR
(CDCl3, 100 MHz, ppm) δ 196.6, 178.7, 147.2, 132.3, 131.3, 130.5,
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The Journal of Organic Chemistry
Note
39.1, 24.6, 24.5, 21.1; 19F NMR (376 MHz, CDCl3) δ −61.8; HRMS
calcd for C14H14F3NONa (M + Na)+ 292.0925, found 292.0924.
1-Methyl-3-phenyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3q).4,13
Compound 3q was obtained in 67% yield (51 mg) according to the
the Scientific Research Foundation of Qufu Normal University
(BSQD 2012020).
REFERENCES
1
■
general procedure (22 h): H NMR (CDCl3, 400 MHz, ppm) δ 7.42
(1) (a) Banks, R. E., Smart, B. E., Tatlow, J. C., Eds. Organofluorine
Chemistry: Principles and Commercial Applications; Plenum Press: New
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Reactivity Applications; Wiley-VCH: Weinheim, 2004. (c) Ojima, I. In
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Chichester, 2009. (d) Purser, S.; Moore, P. R.; Swallow, S.; Governeur,
V. Chem. Soc. Rev. 2008, 37, 320−330.
(dt, J1 = 1.2 Hz, J2 = 8.9 Hz, 1H), 7.38−7.29 (m, 6H), 7.19 (dt, J1 =
1.0 Hz, J2 = 8.5 Hz, 1H), 6.97 (d, J = 7.8 Hz, 1H), 3.45 (dq, J1 = 10.5
Hz, J2 = 15.2 Hz, 1H), 3.25 (s, 3H), 3.07 (dq, J1 = 10.5 Hz, J2 = 15.0
Hz, 1H); 13C NMR (CDCl3, 100 MHz, ppm) δ 176.9, 144.1, 138.6,
129.1, 128.8, 128.8, 128.0, 126.4, 126.1 (q, J = 2.0 Hz), 125.1 (d, J =
271 Hz), 122.6, 108.8, 51.9 (d, J = 2.0 Hz), 40.9 (q, J = 28 Hz), 26.6;
19F NMR (376 MHz, CDCl3) δ −61.1; HRMS calcd for
(2) (a) Muller, K.; Faeh, C.; Diederich, F. Science 2007, 317, 1881−
C17H14F3NONa (M + Na)+ 328.0925, found 328.0923.
̈
1886. (b) Furuya, T.; Kamlet, A. S.; Ritter, T. Nature 2011, 473, 470−
477. (c) Parsons, A. T.; Buchwald, S. L. Nature 2011, 480, 184−185.
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4521. (e) Wu, X. F.; Neumann, H.; Beller, M. Chem.Asian J. 2012, 7,
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Sodeoka, M. Adv. Synth. Catal. 2010, 352, 2708−2732.
3-Benzyl-1-methyl-3-(2,2,2-trifluoroethyl)indolin-2-one (3r).
Compound 3r was obtained in 68% yield (54 mg) according to the
general procedure (12 h): 1H NMR (CDCl3, 400 MHz, ppm) δ 7.27−
7.22 (m, 2H), 7.12−7.05 (m, 4H), 6.79 (d, J = 6.7 Hz, 2H), 6.62 (d, J
= 7.8 Hz, 1H), 3.11−3.01 (m, 3H), 2.97 (s, 3H), 2.81 (dq, J1 = 10.3
Hz, J2 = 15.1 Hz, 1H); 13C NMR (CDCl3, 100 MHz, ppm) δ 177.3,
144.0, 134.0, 130.1, 128.6, 128.0, 127.6, 127.0, 125.3 (q, J = 276 Hz),
124.5 (q, J = 2.0 Hz), 122.1, 108.1, 50.1 (d, J = 2.0 Hz), 44.7, 39.5 (q, J
= 28 Hz), 25.9; 19F NMR (376 MHz, CDCl3) δ −61.2; HRMS calcd
for C18H16F3NONa (M + Na)+ 342.1082, found 342.1082.
3-(Hydroxymethyl)-1-methyl-3-(2,2,2-trifluoroethyl)indolin-2-one
(3s).4,13 Compound 3s was obtained in 74% yield (48 mg) according
to the general procedure (12 h): 1H NMR (CDCl3, 400 MHz, ppm) δ
7.38 (dt, J1 = 1.2 Hz, J2 = 7.7 Hz, 1H), 7.30 (d, J = 7.2 Hz, 1H), 7.14
(dt, J1 = 0.9 Hz, J2 = 7.6 Hz, 1H), 6.94 (d, J = 7.8 Hz, 1H), 3.77 (d, J
= 10.8 Hz, 1H), 3.68 (d, J = 11.1 Hz, 1H), 3.27 (s, 3H), 3.09 (dq, J1 =
10.8 Hz, J2 = 15.3 Hz, 1H), 2.83 (dq, J1 = 10.4 Hz, J2 = 15.3 Hz, 1H),
2.60 (s, 1H); 13C NMR (CDCl3, 100 MHz, ppm) δ 177.1, 143.7,
129.2, 127.0, 125.6 (q, J = 277 Hz), 124.0 (q, J = 1.3 Hz), 122.9, 108.7,
67.4, 49.8 (d, J = 2 Hz, 1H), 36.4 (q, J = 28 Hz), 26.4; 19F NMR (376
MHz, CDCl3) δ −61.5; HRMS calcd for C12H12F3NO2Na (M + Na)+
282.0718, found 282.0721.
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(1-Methyl-2-oxo-3-(2,2,2-trifluoroethyl)indolin-3-yl)methyl Ace-
tate (3t).4,13 Compound 3t was obtained in 71% yield (53.5 mg)
1
according to the general procedure (36 h): H NMR (CDCl3, 400
MHz, ppm) δ 7.37 (dt, J1 = 1.1 Hz, J2 = 7.8 Hz, 1H), 7.32 (d, J = 7.4
Hz, 1H), 7.12 (t, J = 7.6 Hz, 1H), 6.92 (d, J = 7.8 Hz, 1H), 4.42 (d, J =
10.9 Hz, 1H), 4.10 (d, J = 10.8 Hz, 1H), 3.27 (s, 3H), 2.95−2.82 (m,
2H), 1.99 (s, 3H); 13C NMR (CDCl3, 100 MHz, ppm) δ 175.1, 170.0,
143.6, 129.3, 126.6, 125.2 (q, J = 279 Hz), 124.6 (d, J = 2 Hz), 122.7,
108.5, 67.0, 48.2 (d, J = 2 Hz), 36.8 (q, J = 28 Hz), 26.5, 20.5; 19F
NMR (376 MHz, CDCl3) δ −61.4; HRMS calcd for C14H14F3NO3Na
(M + Na)+ 324.0823, found 324.0820.
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13090.
ASSOCIATED CONTENT
■
S
* Supporting Information
1H and 13C NMR spectra for all compounds prepared. This
material is available free of charge via the Internet at http://
pubs.acs.org/.
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AUTHOR INFORMATION
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Corresponding Author
*Tel: +86 537 4458317. Fax: +86 537 4458317. E-mail:
huawang_qfnu@126.com.
(12) Deb, A.; Manna, S.; Modak, A.; Patra, T.; Maity, S.; Maiti, D.
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (Nos. 21302109, 21302110, and
21375075), the Taishan Scholar Foundation of Shandong
Province, the Excellent Middle-Aged and Young Scientist
Award Foundation of Shandong Province (BS2013YY019), and
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Note
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