Page 5 of 7
The Journal of Organic Chemistry
spectrometer. After the measurements, the sealed cuvette was
(0.1 mmol, 1.0 equiv.), carbon tetrabromide (0.2 mmol, 2.0
1
2
3
4
5
6
7
8
brought back into the glovebox, emptied, cleaned with fluorobenꢀ
zene and dried under a stream of argon before preparation of the
next sample. The luminescence emission spectrum of the photoꢀ
catalyst excited at 420 nm was measured six times (three different
samples measured twice each) and an average was taken as the
standard reference spectrum. The samples containing potential
quenchers were each measured twice and an average was taken.
The emission intensity (I) at a preꢀdefined wavelength was noted
and compared with that of the photocatalyst in isolation (I0). The
amount of decrease in the emission intensity was then quantified
equiv.), the additive (0.1 mmol) and sodium bromide (0.2 mmol,
2.0 equiv.). The flask was purged with a stream of argon, and dry
DMF (1.0 ml) was added with a syringe. The mixture was deꢀ
gassed by freeze–pump–thaw (three cycles) and irradiated with
light from blue LEDs (455 nm). After 14 h, the amount of formed
product and the remaining additive was quantified using GCꢀFID
by adding mesitylene as internal standard.
General Procedure for the PPh3/NBS-Mediated Appel Reac-
tion (Conditions B). To
a mixture of NꢀBromosaccharin
9
(0.2 mmol, 2.0 equiv.) and PPh3 (0.2 mmol, 2.0 equiv.) in dry
CH2Cl2 (1.0 mL, 0.1 M) was added 2ꢀphenylethanol (0.1 mmol,
1.0 equiv.) and the additive (0.1 mmol) at room temperature.
After 5 h of stirring, the amount of formed product and the reꢀ
maining additive was quantified using GCꢀFID by adding mesityꢀ
lene as internal standard.
as a “quenching fraction” (F) defined by the following formula:
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ꢄ
ꢁ
ꢂ
ꢀ % = 100 ꢃ1 − ꢆ %
ꢄꢅ
The structure of the photocatalyst [Ir-F] employed in this study
and the emission wavelength used to calculate the quenching
percentage (F) as well as UV/vis absorption spectra and extinction
coefficients at 455 nm and 365 nm for the selected photocatalyst
can be found in the Supporting Information.
ASSOCIATED CONTENT
Supporting Information
General Procedure for the Cp*Rh-Catalyzed Oxidative Ole-
fination (Conditions A). To a flameꢀdried, Arꢀfilled Schlenkꢀ
flask equipped with a magnetic stirring bar was added AgSbF6
(2.0 mol%) and Cu(OAc)2 (2.1 equiv.) in a glove box. 1 mL of a
stock solution containing acetanilide (1.0 equiv. = 0.20 mmol) and
Detailed screening results, screening procedures, results of screenꢀ
ing verification experiments and spectra. The Supporting Inforꢀ
mation is available free of charge on the ACS Publications webꢀ
site.
t
(Cp*RhCl2)2 (0.5 mol%) in AmOH (1 mL/equiv.) was added
under a stream of argon, followed by styrene (1.5 equiv.) and the
corresponding additive (1.0 equiv.) in quick succession and shakꢀ
ing the flask gently after each addition. The flask was sealed and
the reaction was stirred at 120 °C for 15 h. The reactions were
analyzed by GCꢀFID using mesitylene as internal standard.
General Procedure for the CpERh-Catalyzed Oxidative Ole-
fination (Conditions B). To an ovenꢀdried, airꢀfilled Schlenkꢀ
flask equipped with a magnetic stirring bar was added AgSbF6
(10 mol%) and Cu(OAc)2 • H2O (20 mol%) under air. 1 mL of a
stock solution containing acetanilide (2.0 equiv.) and (CpERhCl2)2
(2.5 mol%) in acetone (1 mL/equiv.) was added, followed by
styrene (1.0 equiv.= 0.2 mmol) and the corresponding additive
(1.0 equiv.) in quick succession and shaking the flask gently after
each addition. The flask was sealed and the reaction was stirred at
room temperature for 15 h. The reactions were analyzed by GCꢀ
FID using mesitylene as internal standard.
General Procedure for the Thermal Amidation of Phenyl
Acetic Acid (Conditions A). 4 Å molsieves were activated under
vacuum by heating with a heat gun at 600 °C for ca. half an hour
and subsequently stored under argon. To an ovenꢀdried, Arꢀfilled
Schlenkꢀflask were added activated 4 Å molsieves (ca. 10 mg),
phenyl acetic acid (1.0 equiv. = 0.20 mmol), the corresponding
additive (1.0 equiv.) and pyrrolidine (2.0 equiv.). The flask was
sealed and the reaction was heated to 150 °C for 2.5 h. The reacꢀ
tion was analyzed by GCꢀFID the internal standard mesitylene.
General Procedure for the Silane-Mediated Amidation of
Phenyl Acetic Acid (Conditions B). To a flameꢀdried, Arꢀfilled
Schlenkꢀflask equipped with a magnetic stirring bar was added the
corresponding additive (1.0 equiv.). 1.6 mL of a stock solution
containing phenyl acetic acid (1.0 equiv. = 0.20 mmol) and pyrꢀ
rolidine (1.0 equiv.) in DMF (1.6 mL) was added under a stream
of argon. After stirring the mixture for a few seconds, phenyl
silane (3.0 equiv.) was added under a stream of argon. The flask
was sealed and the reaction was stirred at room temperature for
5 h. The reaction was analyzed by GCꢀFID using mesitylene as
internal standard.
AUTHOR INFORMATION
Corresponding Author
*glorius@uniꢀmuenster.de
Author Contributions
‡T.G. and M.T. contributed equally.
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENTS
We thank the Deutsche Forschungsgemeinschaft (Leibniz Award)
for generous financial support and Dr. K. Collins (Bayer Pharma
Wuppertal), Dr. L. Candish, L. Pitzer, Dr. M. van Gemmeren, and
S. Vásquez Céspedes (all WWU Münster) for helpful discussions.
REFERENCES
1 (a) Cooper, T. W. J.; Campbell, I. B.; MacDonald, S. J. F. Angew.
Chem., Int. Ed. 2010, 49, 8082. (b) Collins, K. D.; Glorius, F. Acc. Chem.
Res. 2015, 48, 619. (c) Foley, D. J.; Nelson, A.; Marsden, S. P. Angew.
Chem., Int. Ed. 2016, 55, 13650.
2 An illustrative quote: “In other words, [these] conditions are mild,
that illꢀdefined but intuitively meaningful word.” Crossley, S. W. M.;
Obradors, C.; Martinez, R. M.; Shenvi, R. A. Chem. Rev. 2016, 116, 8912.
3 Gensch, T.; Glorius, F. Science 2016, 352, 294.
4 Bess, E. N.; Bischoff, A. J.; Sigman, M. S. Proc. Natl. Acad. Sci.
2014, 111, 14698.
5 Kutchukian, P. S.; Dropinski, J. F.; Dykstra, K. D.; Li, B.; DiRocco,
D. A.; Streckfuss, E. C.; Campeau, L.; Cernak, T.; Vachal, P.; Davies, I.
W.; Krska, S. W.; Dreher, S. D. Chem. Sci. 2016, 7, 2604.
6 (a) Collins, K. D.; Glorius, F. Nat. Chem. 2013, 5, 597. (b) Collins,
K. D.; Glorius, F. Tetrahedron 2013, 69, 7817. (c) Collins, K. D.; Rühꢀ
ling, A.; Glorius, F. Nat. Protoc. 2014, 9, 1348. (d) Collins, K. D.; Rühꢀ
ling, A.; Lied, F.; Glorius, F. Chem. Eur. J. 2014, 20, 3800.
7 Richardson, J.; Ruble, J. C.; Love, E. A.; Berritt, S. J. Org. Chem.
2017, 82, 3741.
8 Anastas, P. T.; Kirchhoff, M. M. Acc. Chem. Res. 2002, 35, 686.
9 For selected reviews on visible light photoredox catalysis, see: (a)
Narayanam, J. M. R.; Stephenson, C. R. J. Chem. Soc. Rev. 2011, 40, 102.
(b) Shi, L.; Xia, W. Chem. Soc. Rev. 2012, 41, 7687. (c) Prier, C. K.;
General Procedure for the Photocatalytic Appel Reaction
(Conditions A). A flameꢀdried 10 ml Schlenk flask with magnetic
stir bar was charged with tris(2,2′ ꢀbipyridyl)ruthenium(II) dihexꢀ
afluorophosphate (0.001 mmol, 1.0 mol%), 2ꢀphenylethanol
5
ACS Paragon Plus Environment