Phenol Derivatives as Coupling Partners with Alkylsilicates in Photoredox/Nickel Dual Catalysis

Article abstract of DOI:10.1021/acs.joc.6b00800

Photoredox/nickel dual catalysis via single electron transmetalation allows coupling of C_sp3-C_sp2 hybridized centers under mild conditions. A procedure for the coupling of electron-deficient aryl triflates, -tosylates, and -mesylates with alkylbis(catecholato)silicates is presented. This method represents the first example of the use of phenol derivatives as electrophilic coupling partners in photoredox/nickel dual catalysis.

Full text of DOI:10.1021/acs.joc.6b00800

Note
pubs.acs.org/joc
Phenol Derivatives as Coupling Partners with Alkylsilicates in
Photoredox/Nickel Dual Catalysis
Niki R. Patel and Gary A. Molander*
Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia,
Pennsylvania 19104-6323, United States
S
* Supporting Information
ABSTRACT: Photoredox/nickel dual catalysis via single electron
3
2
transmetalation allows coupling of Csp −Csp hybridized centers
under mild conditions. A procedure for the coupling of electron-
deficient aryl triflates, -tosylates, and -mesylates with alkylbis-
(catecholato)silicates is presented. This method represents the first
example of the use of phenol derivatives as electrophilic coupling
partners in photoredox/nickel dual catalysis.
other phenol derivatives can be thought of as suitable
replacements in the proposed catalytic cycle (Figure 1).11
ransition-metal-catalyzed cross-couplings have become
Tthe foundation by which synthetic chemists generate
C−C and C−heteroatom bonds.1 Despite the tremendous
impact of such methods, C−C bond-forming reactions using
transition metal catalysts are often restricted to the construction
2
2
3
2
of Csp −Csp bonds, with extension to Csp −Csp cross-couplings
proving challenging.2 Recent developments, however, have
3
2
enabled Csp −Csp bonds to be forged with ease via photo-
redox/nickel dual catalysis.3 In particular, we and others have
recently highlighted the success of alkylbis(catecholato)silicates
as efficient radical precursors in dual catalysis.4 Alkylbis-
(catecholato)silicates undergo facile SET oxidation via
reductive quenching of a variety of photocatalysts that results
5
3
in C−Si bond homolysis to produce Csp -centered radicals.
Because of their low oxidation potentials, the use of
[Ru(bpy)3](PF6)2 as a photocatalyst, which is both commer-
cially available or simply made in-house, is feasible.6
Figure 1. Proposed catalytic cycle for photoredox/Ni dual catalysis
with alkylsilicates and phenol derivatives.
3
2
To date, Csp −Csp cross-couplings via photoredox/nickel
dual catalysis have been carried out using only aryl/alkenyl
halide starting materials.3a,b,4,7 However, phenol derivatives, or
“pseudo-halides”, can often be used as replacements for aryl
halides in traditional transition-metal-catalyzed cross-cou-
plings.8 Despite their use in these reactions, the ability to
cross-couple aryl sulfonate esters with alkyl nucleophiles is
limited, analogous to their halide counterparts.9 Because they
are derived from different feedstocks than aryl halides, aryl
triflates, -tosylates, and -mesylates allow access to cross-coupled
substructures that may be complementary to those derived
from the aryl halides alone. In addition, the ease of synthesis of
aryl sulfonates from the corresponding phenols contrasts with
that of the corresponding halides, which requires halogenation
of arenes or aryl diazonium salts.
To assess the viability of aryl sulfonates in photoredox/Ni
dual catalysis, a preliminary screening revealed an 87%
conversion of 4-acetylphenyl triflate (2a) when the reaction
was conducted in the presence of 1a under our previously
established conditions {2 mol % [Ru(bpy)3](PF6)2, 5 mol %
NiCl2(dme), 5 mol % dtbbpy in DMF (0.1 M), 26 W compact
fluorescence lamp (CFL) or blue LEDs} after 24 h.4b,c,12
Further optimization of this reaction allowed full consumption
of triflate 2a when increasing NiCl2(dme) and dtbbpy loading
to 10 mol % (see Supporting Information), which gave 3a in
95% yield on a 0.5 mmol scale after 36 h.13 Using these
conditions, the full scope of this reaction was explored using 1a
as the silicate coupling partner (Table 1). In addition to triflate
2a, silicate 1a coupled successfully to both 1- and 2-naphthyl
triflates in 94% (3c) and 50% (3d) yields, respectively. Minimal
In an effort to expand the scope of alkylsilicate photoredox/
Ni dual catalytic cross-coupling with suitable electrophiles, the
compatibility of aryl sulfonates was assessed. Because they
possess a similar propensity toward oxidative addition as that of
the corresponding aryl iodides and bromides,10 aryl triflates and
Special Issue: Photocatalysis
Received: April 11, 2016
© XXXX American Chemical Society
A
DOI: 10.1021/acs.joc.6b00800
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The Journal of Organic Chemistry
Note
Table 1. Scope of Aryl Triflates in Photoredox/Ni Cross-
Coupling
Table 2. Scope of Alkylbis(catecholato)silicates in
Photoredox/Ni Cross-Coupling
a b
,
a
a
b
c
R′ = R″ = Et or R′ = H, R″ = i-Pr. NMR yield. Reaction provided
comparable yield when no measures were taken to remove oxygen.
d
Reaction with 3m run on gram scale using 5 mol % [NiCl2(dme)]
and dtbbpy with white LEDs.
alkylsilicates when reacted with triflate 2a. Secondary silicates
1b and 1c were amenable to cross-coupling, generating the
expected products in 63% and 92% yields, respectively.
Additionally, simple primary silicates were amenable to cross-
coupling. Hexyl (1e) and isobutyl (1f) silicate derivatives thus
provided cross-coupled products in 74% and 78% yields,
respectively. Silicate 1f performed well on gram scale,
generating cross-coupled product in 82% yield using 5 mol %
NiCl2(dme) and dtbbpy. Furthermore, the conditions of this
reaction successfully allowed alkyl chains containing both
alkenyl and methoxy functional groups (3n and 3o,
respectively), as well as a seven-membered ring lactam/urea
(1i) to be installed with ease. Importantly, the reaction could
be carried out in the presence of oxygen, and thus no degassing
of solvents was necessary.
Although aryl triflates are often prone to hydrolysis under
basic conditions, aryl tosylates and -mesylates exhibit better
stability and are easier to handle and store. Given the observed
reactivity utilizing aryl triflates as electrophilic coupling partners
in photoredox/nickel dual catalysis in the presence of
alkylbis(catecholato)silicates, the scope of this reaction using
aryl tosylates was explored (Table 3). In the event, acetyl-
a
b
R′ = R″ = Et or R′ = H, R″ = i-Pr. Conversion determined by
c
HPLC. Inseparable aryl dimer present in H and 13C NMRs.
1
conversion was observed in the case of 3e, possessing an
electron-donating methoxy group at the para position of the
arene. Additionally, although this reaction has been shown to
work well with electron-deficient aryl triflates, low yields were
obtained when attempting to couple silicate 1a with cyano- and
trifluoromethyl-containing aryl triflates, 2f and 2g, respectively.
Although unreacted starting material remained in the reaction
of 2f, complete conversion of triflate was observed in the case
of 2g, in which the reaction yielded a mixture of cross-coupled
product 3g as well as aryl dimer from the triflate starting
material. It should be noted that dimerization was not observed
in reactions other than those containing trifluoromethyl
functional groups. Interestingly, this reaction proved viable
for meta-substituted aryl triflate derivative 2h, providing cross-
coupled product 3h in good yield.
The scope of alkylbis(catecholato)silicates in this reaction
was next examined (Table 2).14 Moderate to excellent yields
were obtained for a variety of primary and secondary
B
DOI: 10.1021/acs.joc.6b00800
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The Journal of Organic Chemistry
Note
Table 3. Cross-Coupling of Aryl Tosylates with
Table 4. Unsuccessful Cross-Coupling Partners in
Photoredox/Ni Cross-Coupling
a
Alkylbis(catecholato)silicates in Photoredox/Ni Cross-
a
Coupling
a
Reacted using 2 mol % [Ru(bpy)3](PF6), 10 mol % [NiCl2(dme)]
b
c
and 10 mol % dttbpy in DMF (0.1 M). Reacted with 2a. Reacted
with 2c. Reacted with silicate 1a.
d
subjecting 2t to the conditions of the cross-coupling reaction in
the presence of silicate 1a (eq 3), the reaction occurred solely
a
b
R′ = R″ = Et or R′ = H, R″ = i-Pr. Conversion determined by
c
HPLC. Inseparable cyclohexyl dimer impurity present in H and 13C
1
NMRs
containing aryl tosylate 2i showed similar reactivity to its
analogous triflate derivative, furnishing 3a in 80% yield. In
addition, 1-naphthyl tosylate 2j proved a sufficient coupling
partner with secondary silicate 1b. Despite the success of meta-
substituted triflate derivative 2h; however, tosylate 2k did not
prove to be an adequate coupling partner.
Along with triflates and tosylates, mesylates were found to be
competent electrophilic coupling partners in this trans-
formation. Coupling products 3a and 3s were produced in
54% and 72% yields, respectively, using aryl methansulfonates
2l and 2m (eqs 1 and 2). Unfortunately, sulfamate and
carbamate derivatives proved to be unsuccessful coupling
partners under this set of conditions.
at the halide, leaving the triflate virtually unreacted (3t). This
suggests that the faster rate of oxidative addition of the aryl
halide onto Ni(I) is critical in determining reactivity. Reactivity
solely at the halide could allow selective photoredox/Ni-
catalyzed cross-coupling at the bromide followed by subsequent
reactivity at the triflate via photoredox/Ni dual catalysis or by
means of traditional Pd- or Ni-catalyzed cross-coupling.
In summary, electron-deficient aryl sulfonates can be readily
cross-coupled with ammonium alkylbis(catecholato)silicates via
photoredox/nickel dual catalysisprocesses that proceed via
single electron transmetalation under mild conditions. The ease
of SET oxidation of alkylbis(catecholato)silicates to produce
3
Csp centered radicals permits the use of a readily available
photocatalyst. The compatibility of phenol derivatives toward
oxidative addition of nickel centers allows the expansion of
aryl−alkyl couplings via photoredox-nickel dual catalysis to
include sulfonate ester based electrophiles. Electron-deficient
aryl triflates, -tosylates, and -mesylates have been shown to be
successful electrophilic coupling partners in the described cross-
coupling reaction. This method represents the first example of
the use of phenol derivatives as electrophilic coupling partners
in photoredox/nickel dual catalysis.
In addition to the substrates described above, other
alkylsilicates and aryl triflates were attempted in the cross-
coupling (Table 4). In general, we observed reduced yields
using electron-rich substrates, likely because of the additive
effects of this class of substrate with the diminished rate of
oxidative addition into aryl sulfonate esters compared to their
analogous halide counterparts. Despite the previous success of
nitrogen-containing silicates with aryl- and alkenyl halides,4b,c 1j
and 1k proved to be poor nucleophilic coupling partners for
this transformation when reacted with 2a and 2c. In addition,
triflates 2n−2s proved to be unsuccessful when reacted with
silicate 1a, generating little to no cross-coupled product after 48
h.
EXPERIMENTAL SECTION
■
General Procedure for Photoredox Cross-Coupling. 3-(4-
Acetylphenyl)propyl Acetate (3a).15 To a 2 dram, clear glass vial
equipped with a Teflon-coated magnetic stir bar were added 4,4′-di-
tert-butyl-2,2′-bipyridine (13.4 mg, 0.050 mmol) and [NiCl2(dme)]
(11 mg, 0.050 mmol). The vial was sealed and evacuated three times
via an inlet needle and purged with argon. Once purged, 1.5 mL of
THF was introduced. The resulting suspension was heated briefly with
a heat gun until the nickel and ligand were fully solubilized, yielding a
pale green solution. Solvents were then evaporated in vacuo to give a
fine coating of the ligated nickel complex. Once dry, a phenol
derivative (134 mg, 0.5 mmol, 1.0 equiv) (liquid phenol derivatives
were added with solvent), alkylsilicate (335 mg, 0.75 mmol, 1.5 equiv),
and [Ru(bpy)3]2PF6 (8.6 mg, 0.01 mmol) were added in succession.
In view of the previously reported relative reactivity of aryl
halides in this reaction,4b the competition between aryl triflates
and -bromides in the cross-coupling was next assessed. When
C
DOI: 10.1021/acs.joc.6b00800
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The Journal of Organic Chemistry
Note
Under an inert atmosphere, DMF (5 mL) was introduced. The cap
was sealed with Parafilm, and the solution was irradiated in front of a
26 W CFL bulb or blue LEDs. The temperature of the reaction was
maintained at approximately 27 °C via a fan. The solution was stirred
vigorously while being irradiated. The reaction progress was
monitored by HPLC or GC/MS. Once judged to be complete, the
solution was transferred to a separatory funnel and diluted with
deionized H2O (∼20 mL) and Et2O (∼20 mL). The layers were
separated, and the aqueous layer was extracted with Et2O (3 × ∼20
mL). The combined organic layers were washed with 1 M NaOH
(∼30 mL), 1 M HCl (∼30 mL), and brine (∼50 mL). The organic
layer was dried (MgSO4), and the solvent was removed in vacuo by
rotary evaporation. Further purification was accomplished via column
chromatography, eluting with hexane/EtOAc to give the desired
compound as a light yellow oil (102 mg, 95%). 1H NMR (CDCl3, 500
MHz): δ 7.89 (d, J = 8.3 Hz, 2H), 7.28 (d, J = 8.3 Hz, 2H), 4.09 (t, J =
6.5 Hz, 2H), 2.75 (t, J = 7.6 Hz, 2H), 2.59 (s, 3H), 2.05 (s, 3H), 2.02−
1.93 (m, 2H). 13C {1H} NMR (CDCl3, 125 MHz): δ 197.8, 171.2,
147.1, 135.4, 128.7, 128.7, 63.7, 32.4, 29.9, 26.7, 21.0.
1604, 1568, 1454, 1411, 1357, 1308, 1267, 1212, 1185, 1139, 1014,
955, 848, 822, 605, 591, 570 cm−1. HRMS (ESI): m/z calcd for
C15H19O [M + H]+ 215.1436, found 215.1436.
1-(4-Hexylphenyl)ethanone (3l).18 Obtained as a colorless oil (76
1
mg, 74%). H NMR (CDCl3, 500 MHz): δ 7.88 (d, J = 8.3 Hz, 2H),
7.27 (d, J = 8.2 Hz, 2H), 2.69−2.62 (t, J = 7.7 Hz, 2H), 2.58 (s, 3H),
1.67−1.58 (m, 2H), 1.38−1.24 (m, 6H), 0.92−0.82 (m, 3H). 13C {1H}
NMR (CDCl3, 125 MHz): δ 197.9, 148.9, 135.0, 128.7, 128.5, 36.1,
31.8, 31.2, 29.0, 26.6, 22.7, 14.2.
1-(4-Isobutylphenyl)ethanone (3m).19 Obtained as a colorless oil
1
(69 mg, 78%). H NMR (CDCl3, 500 MHz): δ 7.87 (d, J = 8.2 Hz,
2H), 7.23 (d, J = 8.3 Hz, 2H), 2.58 (s, 3H), 2.53 (d, J = 7.2 Hz, 2H),
1.90 (m, 1H), 0.91 (d, J = 6.6 Hz, 6H). 13C {1H} NMR (CDCl3, 125
MHz): δ 198.0, 147.7, 135.1, 129.4, 128.4, 45.5, 30.2, 26.6, 22.4.
1-(4-(2-(Cyclohex-3-en-1-yl)ethyl)phenyl)ethanone (3n). Ob-
1
tained as a light yellow oil (62 mg, 55%). H NMR (CDCl3, 500
MHz): δ 7.88 (d, J = 8.1 Hz, 2H), 7.27 (d, J = 8.1 Hz, 2H), 5.71−5.62
(m, 2H), 2.71 (t, J = 7.8 Hz, 2H), 2.58 (s, 3H), 2.20−1.99 (m, 3H),
1.83−1.52 (m, 5H), 1.34−1.21 (m, 1H). 13C {1H} NMR (CDCl3, 125
MHz): δ 197.9, 148.9, 135.1, 128.7, 128.6, 127.2, 126.4, 38.2, 33.4,
33.2, 31.9, 28.9, 26.6, 25.2. IR (neat): ν = 3021, 2912, 2836, 1680,
1605, 1433, 1412, 1356, 1302, 1265, 1181, 1017, 954, 871, 847, 818,
689, 653, 596, 581 cm−1. HRMS (ESI): m/z calcd for C16H21O [M +
H]+ 229.1592, found 229.1590.
3-(Naphthalen-1-yl)propyl Acetate (3c).4b Obtained as a colorless
1
oil (104 mg, 94%). H NMR (CDCl3, 500 MHz): δ 8.02 (d, J = 8.1
Hz, 1H), 7.85 (d, J = 7.9 Hz, 1H), 7.72 (d, J = 7.9 Hz, 1H), 7.55−7.44
(m, 2H), 7.39 (t, J = 7.3 Hz, 1H), 7.32 (d, J = 7.0 Hz, 1H), 4.16 (t, J =
6.5 Hz, 2H), 3.15 (t, J = 7.7 Hz, 2H), 2.15−2.03 (m, 5H). 13C {1H}
NMR (CDCl3, 125 MHz): δ 171.2, 137.3, 134.0, 131.9, 128.9, 127.0,
126.1, 126.0, 125.6, 125.6, 123.7, 64.2, 29.6, 29.4, 21.1.
1-(4-(3-Methoxypropyl)phenyl)ethanone (3o). Obtained as a
1
colorless oil (72 mg, 75%). H NMR (CDCl3, 500 MHz): δ 7.89
3-(Naphthalen-2-yl)propyl Acetate (3d).16 Obtained as a colorless
oil (57 mg, 50%). 1H NMR (CDCl3, 500 MHz): δ 7.83−7.74 (m, 3H),
7.62 (s, 1H), 7.48−7.38 (m, 2H), 7.32 (dd, J = 8.4, 1.8 Hz, 1H), 4.13
(t, J = 6.6 Hz, 2H), 2.85 (t, J = 7.6 Hz, 2H), 2.09−2.01 (m, 5H). 13C
{1H} NMR (CDCl3, 125 MHz): δ 171.2, 138.8, 133.7, 132.2, 128.1,
127.7, 127.5, 127.2, 126.6, 126.1, 125.3, 64.0, 32.5, 30.2, 21.1.
3-(4-Cyanophenyl)propyl Acetate (3f). Obtained as a colorless oil
(d, J = 8.2 Hz, 2H), 7.28 (d, J = 8.2 Hz, 2H), 3.38 (t, J = 6.3 Hz, 2H),
3.34 (s, 3H), 2.75 (t, J = 7.8 Hz, 2H), 2.58 (s, 3H), 1.95−1.85 (m,
2H). 13C {1H} NMR (CDCl3, 125 MHz): δ 197.9, 147.9, 135.2, 128.8,
128.6, 71.7, 58.7, 32.4, 31.0, 26.6. IR (neat): ν = 2926, 2867, 1679,
1606, 1430, 1412, 1386, 1357, 1266, 1207, 1181, 1115, 1073, 1017,
955, 886, 845, 814, 597, 584 cm−1. HRMS (ESI): m/z calcd for
C12H17O2 [M + H]+ 193.1229, found 193.1231.
1
(31 mg, 30%). H NMR (CDCl3, 500 MHz): δ 7.58 (d, J = 7.3 Hz,
N-(3-(4-Acetylphenyl)propyl)-2-oxoazepane-1-carboxamide (3p).
1
2H), 7.27 (d, J = 7.7 Hz, 2H), 4.09 (t, J = 6.2 Hz, 2H), 2.75 (t, J = 7.7
Hz, 2H), 2.04 (s, 3H), 2.04−1.93 (m, 2H). 13C {1H} NMR (CDCl3,
125 MHz): δ 171.3, 146.9, 132.4, 129.3, 119.0, 110.2, 63.5, 32.5, 29.8,
21.0. IR (neat): ν = 2957, 2227, 1734, 1608, 1505, 1453, 1415, 1387,
1366, 1234, 1178, 1038, 915, 878, 846, 815, 733, 633, 606, 559 cm−1.
HRMS (ESI): m/z calcd for C12H13NO2Na [M + Na]+ 226.0844,
found 226.0834.
Obtained as a colorless oil (86 mg, 57%). H NMR (CDCl3, 500
MHz): δ 9.35 (br s, 1H), 7.88 (d, J = 8.3 Hz, 2H), 7.29 (d, J = 8.2 Hz,
2H), 4.03−3.93 (m, 2H), 3.32 (q, J = 5.7 Hz, 2H), 2.77−2.66 (m,
4H), 2.58 (s, 3H), 1.96−1.86 (m, 2H), 1.81−1.67 (m, 6H). 13C {1H}
NMR (CDCl3, 125 MHz): δ 197.9, 179.6, 155.0, 147.4, 135.2, 128.7,
128.7, 43.9, 40.0, 39.9, 33.3, 30.8, 29.2, 28.4, 26.7, 23.6. IR (neat): ν =
1695, 1680, 1651, 1606, 1526, 1453, 1435, 1397, 1358, 1333, 1267,
1213, 1179, 1163, 1082, 969, 844, 729, 645, 595 cm−1. HRMS (ESI):
m/z calcd for C18H25N2O3 [M + H]+ 317.1865, found 317.1877.
1-Cyclohexylnaphthalene (3q).20 Obtained as a yellow semisolid
3-(4-(Trifluoromethyl)phenyl)propyl Acetate (3g).4e Obtained as a
colorless oil (61 mg, 42%). 1H NMR (CDCl3, 500 MHz): δ 7.56 (d, J
= 8.0 Hz, 2H), 7.31 (d, J = 7.9 Hz, 2H), 4.10 (t, J = 6.5 Hz, 2H), 2.76
(t, J = 7.8 Hz, 2H), 2.06 (s, 3H), 2.03−1.95 (m, 2H). 13C {1H} NMR
(CDCl3, 125 MHz): δ 171.2, 145.4, 128.8, 128.6 (q, J = 32.3 Hz),
125.5 (q, J = 3.8 Hz), 122.3 (q, J = 271.9 Hz), 63.7, 32.2, 30.0, 21.1.
3-(3-(Trifluoromethyl)phenyl)propyl Acetate (3h). Obtained as a
1
(69 mg, 63%). H NMR (CDCl3, 500 MHz): 8.11 (d, J = 8.5, 1H),
7.84 (d, J = 7.8, 1H), 7.68 (d, J = 8.0, 1H), 7.52−7.35 (m, 4H), 3.34−
3.30 (m, 1H), 2.10−1.80 (m, 5H), 1.75−1.49 (m, 4H), 1.40−1.28 (m,
1H). 13C {1H} NMR (CDCl3, 125 MHz): δ 143.9, 134.0, 131.5, 129.0,
126.3, 125.8, 125.7, 125.3, 123.3, 122.4, 39.4, 34.3, 27.4, 26.7.
( )-1-Bicyclo[2.2.1]heptan-2-yl)naphthalene (3s). Obtained as a
colorless oil (80 mg, 72%). 1H NMR (CDCl3, 500 MHz): δ 8.09 (d, J
= 8.3 Hz, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.67 (d, J = 7.5 Hz, 1H),
7.53−7.43 (m, 2H), 7.43−7.34 (m, 2H), 3.43−3.32 (m, 1H), 2.59 (d, J
= 3.5 Hz, 1H), 2.38 (s, 1H), 2.02−1.94 (m, 1 H), 1.79−1.58 (m, 4H),
1.57−1.22 (m, 3H). 13C {1H} NMR (CDCl3, 125 MHz): δ 143.2,
134.2, 132.1, 128.9, 126.1, 125.6, 125.5, 125.4, 124.4, 121.7, 43.4, 41.7,
39.7, 37.1, 36.7, 30.6, 29.4. IR (neat): ν = 2948, 2868, 1739, 1596,
1509, 1452, 1396, 1372, 1311, 1297, 1239, 1139, 1045, 950, 907, 793,
775, 731, 648, 560 cm−1. HRMS (ESI): m/z calcd for C17H18 [M+]
222.1409, found 222.1414.
3-(4-(((Trifluoromethyl)sulfonyl)oxy)phenyl)propyl Acetate (3t).
Obtained as a yellow oil (167 mg, 97%). 1H NMR (CDCl3, 500
MHz): δ 7.26 (d, J = 8.6 Hz, 2H), 7.19 (d, J = 8.6 Hz, 2H), 4.09 (t, J =
6.4 Hz, 2H), 2.72 (t, J = 7.6 Hz, 2H), 2.05 (s, 3H), 2.00−1.92 (m,
2H). 13C {1H} NMR (CDCl3, 125 MHz): δ 171.2, 148.0, 141.9, 130.2,
121.4, 118.8 (q, J = 319.5 Hz), 63.6, 31.7, 30.1, 21.0. 19F NMR
(CDCl3, 470 MHz): −72.9. IR (neat): ν = 1737, 1501, 1419, 1367,
1246, 1205, 1179, 1135, 1039, 1017, 884, 846, 813, 734, 638, 606, 568,
535, 517, 498 cm−1. HRMS (ESI): m/z calcd for C12H13F3O5SNa [M
+ Na]+ 349.0333, found 349.0334.
1
colorless oil (103 mg, 84%). H NMR (CDCl3, 500 MHz): δ 7.49−
7.34 (m, 4H), 4.10 (t, J = 6.5 Hz, 2H), 2.75 (t, J = 7.5 Hz, 2H), 2.05
(s, 3H), 2.03−1.93 (m, 2H). 13C {1H} NMR (CDCl3, 125 MHz): δ
171.2, 142.2, 131.9, 129.0, 130.9 (q, J = 32.0 Hz), 125.2 (q, J = 3.7
Hz), 124.3 (q, J = 272.2 Hz), 123.1 (q, J = 3.9 Hz), 63.7, 32.2, 30.1,
21.0. 19F NMR (CDCl3, 470 MHz): −62.6. IR (neat): ν = 1737, 1450,
1388, 1367, 1328, 1236, 1199, 1161, 1120, 1072, 1039, 1002, 951, 904,
799, 733, 702, 661, 631, 606 cm−1. HRMS (ESI): m/z calcd for
C12H13F3O2Na [M + Na]+ 269.0765, found 269.0754.
1-(4-Cyclohexylphenyl)ethanone (3i).17 Obtained as a white solid
1
(63 mg, 63%); mp, 57−58 °C. H NMR (CDCl3, 500 MHz): δ 7.89
(d, J = 8.3 Hz, 2H), 7.29 (d, J = 8.2 Hz, 2H), 2.58 (m, 4H), 1.92−1.81
(m, 4H), 1.80−1.72 (m, 1H), 1.50−1.34 (m, 4H), 1.33−1.18 (m, 1H).
13C {1H} NMR (CDCl3, 125 MHz): δ 197.9, 153.8, 135.2, 128.6,
127.1, 44.8, 34.2, 26.8, 26.6, 26.1.
( )-1-(4-(Bicyclo[2.2.1]heptan-2-yl)phenyl)ethanone (3j). Ob-
1
tained as a yellow oil (92 mg, 92%). H NMR (CDCl3, 500 MHz):
δ 7.87 (d, J = 8.5 Hz, 2H), 7.30 (d, J = 8.3 Hz, 2H), 2.83−2.75 (m,
1H), 2.57 (s, 3H), 2.42−2.34 (m, 2H), 1.84−1.70 (m, 1H), 1.69−1.48
(m, 3H), 1.41−1.34 (m, 1H), 1.33−1.18 (m, 3H). 13C {1H} NMR
(CDCl3, 125 MHz): δ 197.9, 153.5, 134.8, 128.5, 127.3, 47.6, 42.8,
39.2, 37.0, 36.3, 30.7, 28.9, 26.6. IR (neat): ν = 2949, 2869, 1679,
D
DOI: 10.1021/acs.joc.6b00800
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
(10) (a) Jutand, A.; Mosleh, A. Organometallics 1995, 14, 1810.
(b) Jutand, A.; Mosleh, A. J. Org. Chem. 1997, 62, 261. (c) Alcazar-
Roman, L. M.; Hartwig, J. F. Organometallics 2002, 21, 491.
(11) For a detailed computational study of photoredox/nickel dual
catalysis utilizing aryl halides, see: Gutierrez, O.; Tellis, J. C.; Primer,
D. N.; Molander, G. A.; Kozlowski, M. C. J. Am. Chem. Soc. 2015, 137,
4896.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.joc.6b00800.
Additional experimental details and spectral data (PDF)
(12) Despite extensive studies using alkyltrifluoroborates as radical
precursors in photoredox/nickel dual catalysis, the use of such starting
materials has yet to prove fruitful for coupling to aryl sulfonate esters.
(13) Control studies showed that light, a Ru photocatalyst, and Ni as
well as ligand catalysts were essential for reaction success; without
these components, trace conversion to a cross-coupled product was
observed.
(14) Note that both diisopropylammonium and triethylammonium
counterions on alkylbis(catecholato)silicates show no difference in
reactivity or yield.
(15) Li, X.; Wang, W.; Zhang, C. Adv. Synth. Catal. 2009, 351, 2342.
(16) Kim, D. W.; Hong, D. J.; Seo, J. W.; Kim, H. S.; Kim, H. K.;
Song, C. E.; Chi, D. Y. J. Org. Chem. 2004, 69, 3186.
(17) Guo, X.; Li, C. Org. Lett. 2011, 13, 4977.
(18) Shen, Z.; Goh, K. K. K.; Yang, Y.; Lai, Y.; Wong, C. H. A.;
Cheong, H.; Loh, T. Angew. Chem., Int. Ed. 2011, 50, 511.
(19) Bellale, E. V.; Bhalerao, D. S.; Akamanchi, K. G. J. Org. Chem.
2008, 73, 9473.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: gmolandr@sas.upenn.edu.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Dr. Matthieu Jouffroy and Kingson Lin (University
of Pennsylvania) for the preparation of alkylsilicates. We thank
NIGMS (RO1 GM113878) for financial support of this
research. We thank Evonik for their generous donation of
trialkoxysilanes for the synthesis of alkylbis(catecholato)
silicates.
(20) Czaplik, W. M.; Mayer, M.; von Wangelin, A. J. Angew. Chem.,
Int. Ed. 2009, 48, 607.
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DOI: 10.1021/acs.joc.6b00800
J. Org. Chem. XXXX, XXX, XXX−XXX