Synthesis of α-CF3 ketones from alkenes and electrophilic trifluoromethylating reagents by visible-light driven photoredox catalysis

Article abstract of DOI:10.1016/j.jfluchem.2014.05.013

α-Trifluoromethyl ketones are important fluorinated intermediates and products in chemical synthesis and medicinal development. Herein, visible light-catalyzed photoredox trifluoromethylation of 1-aryl-2-alkyl substituted alkenes using an electrophilic tr

Full text of DOI:10.1016/j.jfluchem.2014.05.013

Accepted Manuscript
Title: Synthesis of ␣-CF3 ketones from alkenes and
electrophilic trifluoromethylating reagents by visible-light
driven photoredox catalysis
Author: Lun Li Qing-Yun Chen Yong Guo
PII:
S0022-1139(14)00142-0
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.jfluchem.2014.05.013
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Revised date:
Accepted date:
20-3-2014
27-5-2014
28-5-2014
Please cite this article as: L. Li, Q.-Y. Chen, Y. Guo, Synthesis of rmalpha-
CF3 ketones from alkenes and electrophilic trifluoromethylating reagents by
visible-light driven photoredox catalysis, Journal of Fluorine Chemistry (2014),
http://dx.doi.org/10.1016/j.jfluchem.2014.05.013
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Synthesis of α-CF3 ketones from alkenes and electrophilic trifluoromethylating
reagents by visible-light driven photoredox catalysis
Lun Li†, Qing-Yun Chen*,† and Yong Guo*,†
† Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R.
of China
yguo@sioc.ac.cn
Introduction
Visible light has been developed as a green resource to promote a wide range of
reactions in the presence of photocatalysts, such as Ru(bpy)3(PF6)2 (1).1 Fluorinated
compounds, especially trifluoromethylated ones, are very useful in a variety of
medicinal, agrochemical, and material applications. These compounds have unique
properties, such as stability, lipophilicity, and bioavailability, that may be attributed to
the presence of fluorine(s).2 Under visible light-promoted conditions, many
trifluoromethylating reagents, e.g., CF3I (3), Togni’s reagent (4), Umemoto’s reagent
(5), and CF3SO2Cl (6), may be converted into trifluoromethyl radicals that can react
with alkenes, alkynes, arenes, and other substrates to give various trifluoromethylated
products (Scheme 1).3
Page 1 of 19

Trifluoromethylating reagents
F3
C
O
I
CF3SO2Cl
CF3SO2Na
CF3I
O
S
Langlois reagent
6
3
BF4
CF3
7
Togni's reagent
Umemoto reagent
4
5
with 5, Gouverneur 2013 JACS
CF3
R1
7
with , Nicewicz 2013 CS
alkenes
including
α,β-unsaturated
with 3, Stephenson 2011, 2012 JACS
X
3
CF3 with , Cho 2012 JOC
or
CF3
R1
R1
carboxylic acid
with 4, Gouverneur 2013 OL
with 6, Han 2014 OL
vinyl borate
4
with , Koike&Akika 2013 CC
with 3, Zhu 2014 CC
3
with , Cho 2013 CEJ
A
allyl silane
with 5, Koike&Akita 2012 ACIE
with 4, Zhu 2013 CEJ
Nu
R1
CF3
5
with , Koike&Akita 2014 OL
R2 R3
with 4, Magnier&Masson 2014 OL
with 5, Koike&Akita 2013 OL
A
H
I
Ru or Ir
alkyne
B
3
with , Cho 2014 ACIE
R
CF3
R
R
Photocatalyst
CF3
CF3
O
B
6
with , Zhang&Yu 2013 EJOC
3
with , MacMillan 2011 ACIE
enol ether
CF3
R1
C
with 3, MacMilan 2009 JACS
R2
with , Kappe 2014 OL
6
C
arene
with 3, Sanford 2012 JACS
including
Ar-CF3
6
with , MacMillan 2011 N
aryl boronic acid
aniline
with 4, Zhu&Ma 2014 OL
D
D
Scheme 1. Summary of visible light photoredox trifluoromethylation
α-Trifluoromethyl ketones are important fluorinated intermediates and products in
chemical synthesis and medicinal development. They are usually synthesized from
ketones or enolates with a radical or electrophilic trifluoromethylating source.4-6
Xiao6h and Maiti6i recently reported the preparation of trifluoromethylated ketones
from alkenes. The reactions involve bisfunctionalization (trifluoromethylation and
oxidation) at the two sides of a double bond. Similarly, when we applied the
photoredox system in the trifluoromethylation of alkenes using an electrophilic
trifluoromethylating reagent, formation of α-trifluoromethylated ketones was
observed.
Results and Discussion
Appropriate conditions for the reaction of anethole (8a) with electrophilic Togni’s
reagent (4) in the presence of a catalytic amount of (1) and excess MgSO4 were
Page 2 of 19

screened. Screening was performed at room temperature under an air atmosphere and
irradiation by a 24-watt fluorescent lamp with various solvents, such as DMF, DMSO,
MeOH, MeCN, DCE, and DMSO (Table 1, Entries 1–5). DMSO was observed to be
the best solvent, producing product 9a in 17% yield (Entry 2). The reaction performed
under a nitrogen atmosphere gave rise to product 9a in 30% yield (Entry 7); the
reaction carried out under an oxygen atmosphere gave a relatively lower yield (Entry
6). Addition of two equivalents of water slightly decreased the yield (20%)(Entry 8).
Addition of more water resulted in a lower yield of 9a (Entries 9 and 10). No 18O
labeled products were found when five equivalents of H2O18 were added into the
solvent (Entry 11). From these experiments, we conclude that the carbonyl oxygen in
the product comes neither from water nor from air. DMSO commonly functions as an
oxidant in several reactions, such as Swern oxidation and Kornblum oxidation.
Therefore, DMSO is the likely source of oxygen in the products. The function of
bases in the reaction was also examined (Entries 12–16). Inorganic bases gave poor
yields. By contrast, the organic base DMAP increased the product yield to 40% (Entry
14). When we tried to improve the yield by adding pyridine N-oxide, we nevertheless
found the reaction solution turned to be dark after the reaction finished (The color
should be brownish red). The 19F NMR yield was not increased, and 19F NMR
spectrum became complex with a lot of small signal observed. When we used
Umemoto reagent 5, the trifluoromethylation of dibenzothiophene happened without
regioselectivity. We also tried dinitro-substituted Umemoto reagent and the reaction
did not occur.
Page 3 of 19

Table 1. Optimization of Reaction Conditionsa
5% Ru(bpy)3(PF6)2
O
MgSO4, solvent, base
+
4
48 h, rt
MeO
CF3
24W fluorescent lamp
MeO
8a
9a
Entry
1c
Solvent
Base
Yield (%)b
trace
17
DMF
-
-
-
-
-
-
-
-
2c
DMSO
MeOH
MeCN
DCE
3c
trace
trace
trace
10f
4c
5c
6e
DMSO
DMSO
DMSO
7
30
8 c,g
9
20
DMSO/H2O=2/1
DMSO/H2O=1/1
DMSO
-
<5d
10e
11h
12
13
14
15
16
-
<5d
-
-
f
DMSO
NaOH
Na2CO3
DMAP
Et3N
-
DMSO
-
DMSO
40
20
DMSO
DMSO
DABCO·H2O 16
Page 4 of 19

aUnless otherwise noted, reaction conditions: 8a (0.2 mmol), 4 (0.4
mmol), Ru(bpy)3(PF6)2 (0.01 mmol), MgSO4 (200 w%), solvent (2
mL), under a nitrogen atmosphere, rt, 48 h; bYield based on 19F NMR.
c
d
Reaction was carried out under an air atomosphere; The 19F NMR
e
spectroscopy displayed a very complex result; Reaction was carried
f
out under an oxygen amosphere; most of olefin was oxidated into
p-anisaldehyde; gTwo equivalents of water was added; hFive
equivalents of H218O was added.
Control experiments were carried out (Table 2). The reaction did not occur in dark
conditions (Table 2, Entry 2). However, without the photocatalyst, the product yield
was as high as 21%, slightly lower than the yield obtained from the standard reaction
(Entry 3). Under natural light, little to no product was generated (Entry 4). The
reaction was promoted by irradiation by a fluorescent lamp and the effect of
irradiation improved the yield when a photocatalyst was used.
Table 2. Control experiments
Entry
Variation from optimized Yield (%)
conditions
1
2
3
4
No change
In Dark
40
0
No catalyst
Nature light
21
< 5%
Under optimal conditions, we tested for the scope of the method on aromatic
Page 5 of 19

alkenes (Table 3). Electron-rich alkenes gave low to acceptable yields of products
(9a–9i). No product was found by the use of electron-deficient alkenes (9j). We tried
terminal styrenes (1-methoxy-4-vinylbenzene and styrene) in the same reaction
conditions of propenylaromatics and the results were complex. Only trace product
was observed by 19F NMR spectroscopy, accompanying with a lot of other signals.
Table 3. Scope of substrates
O
5 mol% Ru(bpy)3(PF6)2
MgSO4, DMSO, DMAP
4
+
R
R
N2, 48h
CF3
24W fluorescent lamp
8
9
O
OMe O
OMe O
CF3
CF3
CF3
MeO
OMe
9a
9b
9e
9c
17%
40%
27%
O
O
O
MeO
MeO
Br
MeO
MeO
CF3
CF3
CF3
OMe
MeO
OMe
9d 29%
20%
9f 31%
O
O
O
MeO
CF3
CF3
CF3
OMe
MeO
MeO
OMe
OMe
9h 8%
9g 23%
9i 13%
O
CF3
O2N
The yields are all isolated yields.
9j
0%
[t1]
To understand the mechanism of the present reaction better, we added
2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) to the reaction. The reaction was
inhibited by TEMPO (Scheme 2). A “radical clock” (8k) was synthesized, and the
Page 6 of 19

reaction of 8k was carried out under standard reaction conditions, giving rise to 9k.
This latter product was identified and characterized using GC-MS and 19F NMR
spectroscopy. Results suggest that the reaction involves a radical process.
We propose two mechanisms to explain the present reaction, as outlined in
Scheme 3. In path A, Ru(II)(bpy)3 undergoes metal-to-ligand transfer when irradiated
with visible light, thereby producing a redox-active photoexcited state, Ru*(II)(bpy)3.
Togni’s reagent (4) functions as an oxidative quencher, oxidizes Ru*(II)(bpy)3 into
Ru(III)(bpy)3, and generates a CF3 radical. The CF3 radical adds to alkene 8, yielding
an intermediate (Int I). Int I is oxidized by Ru(III)(bpy)3 to give another intermediate
(Int II) with regeneration of Ru(II)(bpy)3. Int II abstracts an oxygen atom from
DMSO, thereby producing α-CF3 ketone 9, the target compound. In path B,
Ru(III)(bpy)3 oxidizes the electron-rich alkene 8 into a radical cation intermediate
(Int III), which is an intermediate proposed in cycloaddition reactions by visible light
photocatalysis.7 Int III is further stabilized by DMSO to form a radical intermediate
(Int IV). Int IV combines with a CF3 radical to give a cation intermediate (Int V).
Further deprotonation and simultaneous leaving of dimethyl sulfide yield the product
9. A mechanism that can explain the occurrence of the reaction under fluorescence
irradiation in the absence of a photocatalyst has yet to be elucidated. The occurrence
of the reaction under fluorescence irradiation in the absence of a photocatalyst could
be explained by a photon-induced charge-transfer complex mechanism. A similar
mechanism is proposed in trifluoromethylation of silylketene acetal of δ-valerolactone
by MacMillan and his coworkers.3c Their reactions also happened in the presence of a
Page 7 of 19

fluorescent light, without the requirement of the photoredox catalyst.
Standard conditions
8a
4
+
NR
TEMPO
MeO
MeO
Standard conditions
O
+ 4
O
CF3
O
8k
9k
Scheme 2. Mechanistic experiments
Fluorescent light
Path A
Ru(II)(bpy)3
Ru*(II)(bpy)3
Me
DMSO
9
4
F3C
Ar
Int II
Ru(III)(bpy)3
Me
CF3
F3C
Int I
Ar
8
Path B
Fluorescent light
Ru(II)(bpy)3
Ru*(II)(bpy)3
8
4
Ru(III)(bpy)3
Me
CF3
Ar
Me
Int III
Me
CF3
Ar
9
O
S
Ar
O
S
DMSO
Int IV
Int V
Scheme 3. Proposed Mechanism
Page 8 of 19

Conclusion
In summary, the reactions of non-terminal styrenes with Togni’s reagent under
visible light photoredox conditions gave α-trifluoromethyl ketones in acceptable
yields. The reaction could occur in a lower yield in the absence of a photocatalyst. In
the case of terminal styrenes, the reaction were complex according to the observation
by 19F NMR spectroscopy. The reaction can be applied to a variety of electron-rich
non-terminal styrenes. Considering the high availability of alkenes, this method
provides a facile access to α-trifluoromethyl ketones.
Experimental Section
General experiment details DMSO were purified by distillation over CaH2. NMR
spectra were obtained on 300 or 400 MHz spectrometers and recorded at 25 °C.
1
Chemical shifts for H NMR spectra are reported in ppm downfield from TMS,
chemical shifts for 13C NMR spectra are recorded in ppm relative to internal chloroform
(δ 77.0 ppm for 13C), chemical shifts for 19F NMR are reported in ppm downfield from
fluorotrichloromethane (CFCl3). Coupling constants (J) are reported in hertz. The terms
m, s, d, t, and q refer to multiplet, singlet, doublet, triplet, and quartet, respectively. 13C
NMR was broad-band decoupled from hydrogen nuclei. Infrared spectra (IR) were
recorded with an infrared spectrometer; absorbance frequencies are given at maximum
intensity in cm−1. The mass analyzer type uesd for the HRMS is time of flight mass
spectrometry (TOF-MS) or Fourier transform ion cyclotron resonance mass
spectrometry (FTICR-MS). Column chromatography was performed using silica gel
(mesh 300–400).
Page 9 of 19

General procedure of Trifluoromethylation of alkenes. A 10 mL Schlenk tude
was charged with a stir bar, Ru(bpy)3(PF6)2 (0.01 mmol,), MgSO4 (200 w%), Togni’s
reagent (0.4 mmol), and DMAP (0.4 mmol) under N2 atmosphere. To the mixture,
DMSO (2 mL) and alkenes (0.2 mmol) were added. The mixture was stirred at room
temperature and under the exposure in the 24 W fluorescent lamp for 48 h. Then, 8
mL water was added. The resulting mixture was extracted with DCM (4 mL × 3). The
organic extracts were washed by brine, dried over anhydrous Na2SO4 and
concentrated in vacuo. The residue was purified by column chromatography on silica
gel.
3,3,3-trifluoro-1-(4-methoxyphenyl)-2-methylpropan-1-one (9a): colorless oil;
IR(KBr) ν/cm-1: 2998, 2953, 2843, 1682, 1608, 1514, 1463, 1132, 846; 1H NMR
(CDCl3, 300 MHz) δ: 1.46 (d, J = 7.0 Hz, 3H), 3.89 (s, 3H), 4.20 (m, J = 7.9 Hz, 7.0
Hz, 1H), 6.97 (d, J = 8.8 Hz, 2H), 7.95 (d, J = 8.8 Hz, 2H); 19F NMR (CDCl3, 282
MHz) δ: -68.4 (d, J = 7.9 Hz); 13C NMR (CDCl3, 100 MHz) δ: 192.8, 164.2, 131.0,
128.7, 125.4 (q, J = 283 Hz), 114.1, 55.6, 43.9 (q, J = 27 Hz), 11.7 (q, J = 3 Hz);
EI-MS m/z: 232 (M+, 13.95), 135 (100); HRMS Calcd for C11H11O2F3 , 232.0711,
found 232.0712.
1-(2,6-dimethoxyphenyl)-3,3,3-trifluoro-2-methylpropan-1-one (9b): colorless
1
oil; IR(KBr) ν/cm-1: 2998, 2951, 2844, 1716, 1596, 1479, 1256, 1115, 814; H NMR
(CDCl3, 300 MHz) δ: 1.37 (d, J = 7.3 Hz, 3H), 3.79 (s, 6H), 4.03 (m, 1H), 6.56 (d, J =
19
8.2 Hz, 2H), 7.31 (t, J = 8.2 Hz, 1H); F NMR (CDCl3, 282 Hz) δ: -69.0 (d, J = 8.0
Hz); 13C NMR (CDCl3, 100 MHz) δ: 197.5, 157.3, 131.7, 125.4 (q, J = 281 Hz),
Page 10 of 19

118.5, 104.0, 55.9, 50.6 (q, J = 25 Hz), 10.1 (q, J = 3 Hz); EI-MS m/z: 262 (M+,
13.95), 165 (100), 150 (16.07), 107 (14.38), 166 (10.06); HRMS Calcd for
C12H13O3F3 , 262.0817, found 262.0815;
3,3,3-trifluoro-1-(2-methoxyphenyl)-2-methylpropan-1-one (9c): colorless oil;
1
IR(KBr) ν/cm-1: 2998, 2951, 2845, 1686, 1600, 1487, 1246, 1166, 756; H NMR
(CDCl3, 300 MHz) δ: 1.39 (d, J = 7.0 Hz, 3H), 3.91 (s, 3H), 4.40 (m, J = 7.0 Hz, 7.9
Hz, 1H), 6.96 (d, J = 8.5 Hz, 1H), 7.01 (dd, J = 7.9 Hz, 7.5 Hz, 1H), 7.49 (dd, J = 8.5
Hz, 7.5 Hz, 1H), 7.64 (d, J = 7.9 Hz, 1H); 19F NMR (CDCl3, 282 Hz) δ: -68.9 (d, J =
7.9 Hz); 13C NMR (CDCl3, 100 MHz) δ: 196.9, 158.2, 134.3, 130.9, 127.3, 125.7 (q, J
= 287 Hz), 121.1, 111.5, 55.6, 48.8 (q, J = 26 Hz), 11.0 (q, J = 3 Hz); EI-MS m/z: 232
(M+, 19.46), 135 (100), 77 (51.21), 92 (26.06), 136 (20.09); HRMS Calcd for
C11H11O2F3 , 232.0711, found 232.0713.
1-(3-bromo-4-methoxyphenyl)-3,3,3-trifluoro-2-methylpropan-1-one
(9d):
white solid; IR(KBr) ν/cm-1: 3078, 2990, 2947, 2846, 1671, 1593, 1260, 1052, 841;
1H NMR (CDCl3, 300 MHz) δ: 1.47 (d, J = 7.0Hz, 3H), 3.99 (s, 3H), 4.16 (m, 1H),
6.98 (d, J = 8.8Hz, 1H), 7.93 (d, J = 8.8 Hz, 1H), 8.18 (s, 1H); 19F NMR (CDCl3, 282
MHz) δ: -68.7 (d, J = 7.9 Hz); EI-MS m/z: 310 (M+, 12.26), 312 (M+2, 12.34), 213
(100), 215 (97.19), 63 (29.72); HRMS Calcd for C11H10O2F3Br, 309.9816, found
309.9814.
3,3,3-trifluoro-2-methyl-1-(2,4,5-trimethoxyphenyl)propan-1-one
(9e):
1
colorless oil; IR(KBr) ν/cm-1: 2951, 2849, 1667, 1606, 1514, 1404, 1262, 820; H
NMR (CDCl3, 300 MHz) δ: 1.41 (d, J = 7.0 Hz, 3H), 3.88 (s, 3H), 3.95 (s, 3H), 3.97
Page 11 of 19

(s, 3H), 4.52 (m, 1H), 6.50 (s, 2H), 7.39 (s, 1H); 19F NMR (CDCl3, 282 MHz) δ: -68.9
(d, J = 8.0 Hz); EI-MS m/z: 292 (M+, 20.07), 195 (100), 135 (20.64), 163 (15.64), 77
(14.03); HRMS Calcd for C13H15O4F3 , 292.0922, found 292.0923.
3,3,3-trifluoro-2-methyl-1-(3,4,5-trimethoxyphenyl)propan-1-one (9f): colorless
1
oil; IR(KBr) ν/cm-1: 3001, 2945, 2841, 1683, 1584, 1463, 1252, 997; H NMR
(CDCl3, 300 MHz) δ: 1.44 (d, J = 7.3 Hz, 3H), 3.89 (s, 6H), 3.90 (s, 3H), 4.17 (m,
1H), 7.17 (s, 2H); 19F NMR (CDCl3, 282 MHz) δ: -68.7 (d, J = 5.9 Hz); 13C NMR
(CDCl3, 100 MHz) δ: 193.1, 153.2, 143.5, 130.7, 125.2 (q, J = 281 Hz), 106.3, 60.9,
56.3, 43.9 (q, J = 24 Hz), 11.8; EI-MS m/z: 292 (M+, 25.64), 195 (100), 152 (11.25),
77 (8.67), 66 (7.12); HRMS Calcd for C13H15O4F3 , 292.0922, found 292.0919.
1-(3,4-dimethoxyphenyl)-3,3,3-trifluoro-2-methylpropan-1-one (9g): colorless
1
oil; IR(KBr) ν/cm-1: 3084, 2942, 2844, 1682, 1596, 1464, 1266, 1022; H NMR
(CDCl3, 300 MHz) δ: 1.47 (d, J = 7.0 Hz, 3H), 3.95 (s, 3H), 3.97 (s, 3H), 4.23 (m, J =
8.0 Hz, 7.0 Hz, 1H), 6.92 (d, J = 8.8 Hz, 1H), 7.55 (s, 1H), 7.57 (d, J = 8.8 Hz, 1H);
19F NMR (CDCl3, 282 MHz) δ: -68.7 (d, J = 8.0Hz); 13C NMR (CDCl3, 100 MHz) δ:
192.9, 154.1, 149.3, 128.8, 125.2 (q, J = 280 Hz), 123.4, 110.5, 109.9, 56.1, 55.9, 43.7
(q, J = 25.5 Hz), 11.8; EI-MS m/z: 262 (M+, 18.77), 165 (100), 79 (12.59), 77 (12.43),
166 (11.02); HRMS Calcd for C12H13O3F3 , 262.0817, found 262.0815.
1-(2,4-dimethoxyphenyl)-3,3,3-trifluoro-2-methylpropan-1-one (9h): colorless
1
oil; IR(KBr) ν/cm-1: 2959, 2931, 2859, 1674, 1602, 1463, 1253, 1072; H NMR
(CDCl3, 300 MHz) δ: 1.39 (d, J = 7.0 Hz, 3H), 3.87 (s, 3H), 3.92 (s, 3H), 4.45 (m,
1H), 6.46 (s, 1H), 6.56 (d, J = 8.8 Hz, 1H), 7.79 (d, J = 8.8 Hz, 1H); 19F NMR
Page 12 of 19

(CDCl3, 282 MHz) δ: -68.9(d, J = 9.9 Hz); EI-MS m/z: 262 (M+, 18.77), 165 (100),
122 (8.93), 107 (8.35), 77 (7.73); HRMS Calcd for C12H13O3F3 , 262.0817, found
262.0815.
1-(3,5-dimethoxyphenyl)-3,3,3-trifluoro-2-methylpropan-1-one (9i): colorless
1
oil; IR(KBr) ν/cm-1: 3092, 2944, 2841, 1697, 1594, 1458, 1428, 1063; H NMR
(CDCl3, 300 MHz) δ: 1.46 (d, J = 7.3 Hz, 3H), 3.78 (s, 3H), 3.84 (s, 3H), 4.17 (m,
1H), 6. 50 (s, 2H), 7.07 (s, 1H); 19F NMR (CDCl3, 282 MHz) δ: -68.8 (d, J = 8.0 Hz);
EI-MS m/z: 262 (M+, 24.74), 165 (100), 137 (35.17), 77 (19.33), 107 (17.49); HRMS
Calcd for C12H13O3F3 , 262.0817, found 262.0820.
(4-methoxyphenyl)(4-(2,2,2-trifluoroethyl)tetrahydrofuran-3-yl)methanone
(9k): colorless oil; IR(KBr) ν/cm-1: 2941, 2880, 1670, 1600, 1512, 1442, 1173, 839;
19F NMR (CDCl3, 282 MHz) δ: -65.5 (t, J = 9.9 Hz); HRMS Calcd for C14H15O3F3 ,
288.0973, found 288.0969.
Acknowledgments. This work was supported by National Basic Research Program
of China (973 Program) (No. 2012CB821600), National Natural Science Foundation
of China (No. 21032006, 21172241) and Shanghai Science and Technology
Commission (11ZR1445700).
References and Footnotes
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Zeitler, Angew. Chem. Int. Ed. 48 (2009) 9785-9789; (d) Y.-Q. Zou, J.-R. Chen,
W.-J. Xiao, Angew. Chem. Int. Ed. 52 (2013) 11701-11703; (e) F. Teplý, Collect.
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ref 3c and ref 3b.
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Graphical Abstract
F3C
O
I
O
O
R
R
Ru(bpy)3(PF6)2
CF3
visible light
DMSO
Page 18 of 19

Highlights
Synthesis of α‐trifluoromethyl ketones is reported.
Visible light photoredox trifluoromethylation of alkenes is performed.
An electrophilic trifluoromethylating reagent (Togni’s reagent) was used.
The reaction involves a trifluoromethyl radical.
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