Catalytic C-H Bond Alkylation of Azoles with Alkyl Halides Mediated by Nickel(II) Complexes of Phenanthridine-Based N^ N-^ N Pincer Ligands

Article abstract of DOI:10.1021/acs.organomet.0c00161

Ni(II) complexes supported by tridentate N^N^-^N diarylamido pincer-type ligands have been demonstrated to act as active catalysts in the carbon-carbon bond forming alkylation of azoles using unactivated alkyl halides. Here, we show that benzann

Full text of DOI:10.1021/acs.organomet.0c00161

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Article
Catalytic C−H Bond Alkylation of Azoles with Alkyl Halides
Mediated by Nickel(II) Complexes of Phenanthridine-Based N^N−^N
Pincer Ligands
Pavan Mandapati, Jason D. Braun, Baldeep K. Sidhu, Gabrielle Wilson, and David E. Herbert*
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ABSTRACT: Ni(II) complexes supported by tridentate N^N−^N
diarylamido pincer-type ligands have been demonstrated to act as
active catalysts in the carbon−carbon bond forming alkylation of
azoles using unactivated alkyl halides. Here, we show that
benzannulated phenanthridine-containing ligands can form homo-
geneous Ni(II) catalysts active with both benzoxazole and
benzothiazole substrates. These precatalysts have been fully
characterized in solution and the solid state, including by cyclic
voltammetry.
INTRODUCTION
■
The homogeneous catalytic conversion of C−H bonds to C−
C bonds mediated by coordination complexes of first-row
transition metals is of prime interest in the drive to increase
sustainability in chemical synthesis.1,2 First, direct functional-
ization of C−H bonds obviates the need for leaving groups
that can limit atom economy.3 Second, the use of first-row
metal catalysts reduces reliance on less abundant precious
metals for transformations that add value to organic substrates
such as aromatic heterocycles.4 With respect to these widely
used synthetic building blocks, transition metal catalyzed C−H
alkylation reactions using alkyl halides with β-hydrogens can be
challenging, as β-hydride elimination can lead to unproductive
side reactions.5 As a result, a relatively limited number of
examples of such cross-couplings have been reported, with
palladium,6,7 nickel,8−11 and copper12−14 catalysts featuring
most prominently.
Well-defined complexes of nickel supported by diarylamido
N^N−^N pincer-type ligands, in particular, have been shown to
direct the alkylation of oxazoles and thiazoles using unactivated
alkyl halides (Figure 1).8,10 While Ni(II) complexes of bis(2-
(dimethylamino)phenyl)amido ligands (A) show excellent
catalytic activity, as reported by Hu and co-workers, addition
of a copper cocatalyst is necessary to achieve high yields.8
Moreover, decomposition of A was observed over time under
the high temperature reaction conditions, depositing nano-
particulate metal into the reaction mixture.8 Punji and co-
workers elaborated this scaffold into a more robust quinolinyl-
based pincer type analogue. The corresponding Ni chloride
complexes supported by a (2-(dimethylamino)phenyl)(8-
Figure 1. N^N−^N pincer-type ligand supported Ni complexes for the
C−H alkylation of azoles (A, see ref 8; B, see ref 10; C, this work).
quinolinyl)amido donor set (B) exhibit greater temperature
stability and do not require a cocatalyst in the catalytic
alkylation of benzothiazoles.10
We recently described synthetic routes to tridentate,
N^N−^N diarylamido pincer-type ligands bearing benzannu-
lated phenanthridine (3,4-benzoquinoline) heterocyclic donor
arms.15 Compared with (8-amino)quinolines, a relatively
broad range of 2-substituted (4-amino)phenanthridines can
be easily accessed via tandem cross-coupling/condensation
reactions using various 4-substituted anilines;16 accessing 6-
substituted (8-amino)quinolines can require less tractable
Skraup reaction conditions.17 Moreover, in these benzannu-
lated pincer-type frameworks, the phenanthridinyl donor arm
Received: March 5, 2020
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© XXXX American Chemical Society
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Scheme 1. Synthesis of (a) Phenanthridine Precursors, (b) Phenanthridine-Based N^N(H)^N Proligands and Nickel
Complexes, and (c) Methyl-Substituted Quinolinyl Analogues of B,10 Described in This Work
Figure 2. Solid-state structures of 3a−c shown with thermal ellipsoids at 50% probability levels. Hydrogens other than H2 are omitted for clarity.
Selected bond distances (Å) and angles (deg) for 3a: C(1)−N(1) 1.3034(11), C(10)−N(2) 1.3957(10), C(15)−N(2) 1.4124(11), C(16)−N(3)
1.4168(12); C(10)−N(2)−C(15) 122.64(7), C(9)−C(10)−N(2) 117.25(7), C(16)−C(15)−N(2) 121.17(8). 3b: C(1)−N(1) 1.302(3),
C(10)−N(2) 1.386(3), C(18)−N(2) 1.397(3), C(23)−N(3) 1.425(3); C(10)−N(2)−C(18) 128.8(2), C(9)−C(10)−N(2) 115.4(2), C(19)−
C(18)−N(2) 122.4(2). 3c: C(1)−N(1) 1.291(4), C(10)−N(2) 1.374(3), C(15)−N(2) 1.395(4), C(16)−N(3) 1.430(4); C(10)−N(2)−C(15)
129.9(2), C(9)−C(10)−N(2) 116.2(2), C(16)−C(15)−N(2) 116.6(3).
can act as an efficient Lewis base with strong π-acid character
thanks to the presence of low-lying vacant orbitals18 and are
sterically less encumbered than isomeric acridines.19 As
mechanistic studies of azole alkylation reactions mediated by
B suggest involvement of a Ni(II)/Ni(III) redox couple,20 we
decided to apply our phenanthridine-containing ligand
architecture in the preparation of π-extended Ni(II) analogues
(C) to probe the impact of π-extension on the stability of
higher oxidation states21 and potentially with it, catalytic
activity. We report here that complexes of the type C are
competent in the catalytic C−H bond alkylation of azoles with
unactivated alkyl halides containing β-hydrogens, with activity
and good substrate scope comparable to A and B without the
requirement of a Cu cocatalyst.
coupling/condensation reactions15,16 to produce 1a−c
(Scheme 1). These were then reduced to the corresponding
(4-amino)phenanthridines 2a−c and coupled with (N,N-
dimethyl)(2-bromo-4-methyl)aniline using Pd-catalyzed C−N
bond formation to give proligands 3a−c as yellow solids, which
could be purified using column chromatography. For each of
the amine proligands, the hydrogen in the 6-position of the
phenanthridine framework resonates significantly downfield of
1
the remaining aromatic resonances in the H NMR spectrum,
indicating formation of the tricyclic phenanthridine.22 The
appearance of a broad singlet assigned to an N−H signal
similarly confirmed formation of the diarylamine unit. For
comparison, the (6-methyl)quinolinyl analogue 5 was also
prepared via Pd-catalyzed C−N coupling.
The solid-state structures of the phenanthridine-containing
proligands 3a−c were determined using single crystal X-ray
diffraction (Figure 2). Consistent with the general importance
of “imine-bridged biphenyl” resonance contributors to the
ground-state structure of phenanthridines,23 the C−N distance
between the phenanthridinyl nitrogen and the adjacent carbon
in the 6-position is quite short in all three proligands [3a:
RESULTS AND DISCUSSION
■
Synthesis and Characterization of Proligands and
Their Coordination Complexes. To access the proligands
used in this work, aminophenanthridines/quinolines suitable
for elaboration into the target scaffolds were prepared. First,
(4-nitro)phenanthridines were assembled via tandem cross-
B
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Figure 3. Solid-state structure of 4a, 4b, and 6 shown with thermal ellipsoids at 50% probability levels. Hydrogens are omitted for clarity. Selected
bond distances (Å) and angles (deg) for 4a: Ni(1)−Cl(1) 2.1919(8), Ni(1)−N(1) 1.895(2), Ni(1)−N(2) 1.848(2), Ni(1)−N(3) 1.951(2),
C(1)−N(1) 1.304(4); N(1)−Ni(1)−N(3) 170.83(10), Cl(1)−Ni(1)−N(2) 179.08(8), N(1)−Ni(1)−N(2) 84.95(10), N(3)−Ni(1)−N(2)
86.35(10), N(1)−Ni(1)−Cl(1) 94.03(7), N(3)−Ni(1)−Cl(1) 93.62(7). 4b: Ni(1)−Cl(1) 2.1950(5), Ni(1)−N(1) 1.8937(14), Ni(1)−N(2)
1.8511(14), Ni(1)−N(3) 1.9512(15), C(1)−N(1) 1.316(2); N(1)−Ni(1)−N(3) 171.60(6), Cl(1)−Ni(1)−N(2) 176.71(5), N(1)−Ni(1)−N(2)
85.12(6), N(3)−Ni(1)−N(2) 86.49(6), N(1)−Ni(1)−Cl(1) 94.50(5), N(3)−Ni(1)−Cl(1) 93.90(5). 6: Ni(1)−Cl(1) 2.2094(9), Ni(1)−N(1)
1.896(2), Ni(1)−N(2) 1.859(2), Ni(1)−N(3) 1.949(2), C(1)−N(1) 1.326(4); N(1)−Ni(1)−N(3) 170.93(10), Cl(1)−Ni(1)−N(2) 176.84(8),
N(1)−Ni(1)−N(2) 84.69(10), N(3)−Ni(1)−N(2) 86.25(10), N(1)−Ni(1)−Cl(1) 94.59(8), N(3)−Ni(1)−Cl(1) 94.42(7).
C(1)−N(1) 1.3034(11); 3b: C(1)−N(1) 1.302(3); 3c:
C(1)−N(1) 1.291(4)] pointing to localization of imine C
N character at this site.18 The localization of imine CN π
character at this site has been shown to temper the impacts of
π-extension, for example, in emissive complexes of phenan-
thridinyl-based ligands.22,24
Table 1. Catalyst Comparison for [Ni]-Catalyzed Alkylation
of Benzannulated Azoles
a
With the proligands in hand, Ni(II) coordination complexes
4a−c and the quinoline congener 6 were synthesized through
metalation with NiCl2·6H2O in the presence of base (sodium
tert-butoxide) in dichloromethane at elevated temperatures,
and isolated in good yields (83−93%) as dark red solids. The
disappearance of the signal assigned to the N−H resonance in
b
entry
catalyst
heterocycle
alkyl halide
yield
1
2
3
4
5
6
7
4a
4b
4c
6
4a
4b
4c
4c
4c
4c
4c
6
H1
H1
H1
H1
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
H2
A1
A1
A1
A1
A1
A1
A1
A1
A1
A1
A1
A1
A2
A2
A3
49
49
42
61
46
39
73
63
55
65
0
1
the H NMR spectrum and shifts to the remaining signals,
including the diagnostic signals for the hydrogen nucleus in the
6-position of the phenanthridinyl/quinolinyl arms, confirmed
installation of the ligand frameworks on the Ni(II) ion. The
geometry and structures of the (N^N^N)NiCl complexes were
determined using single-crystal X-ray diffraction (Figure 3). In
keeping with analogous complexes such as B,10 the nickel ions
in 4a,b and 6 sit within the meridional pocket formed by the
N^N−^N diarylamido ligand. All complexes are essentially flat
(angles between planes formed by six carbon rings (e.g., C8−
C13 and C15−C20 for 4a) flanking the amido nitrogens: 4a
9.43°, 4b 3.49°, 6 10.42°), but with distorted square-planar
geometry resulting from tied-back bond angles formed by the
two neutral donor arms [4a: N(1)−Ni(1)−N(3) 170.83(10);
4b: N(1)−Ni(1)−N(3) 171.60(6); 6: N(1)−Ni(1)−N(3)
170.93(10)°]. The Ni−Namido distances (4a: 1.848(2); 4b:
1.8511(14); 6: 1.859(2) Å] are within range of those reported
for A25 and B,10 and shorter than between nickel and the
neutral donor arms [4a: Ni(1)−N(1) 1.895(2), Ni(1)−N(3)
1.951(2); 4b: Ni(1)−N(1) 1.8937(14), Ni(1)−N(3)
1.9512(15); 6: Ni(1)−N(1) 1.896(2), Ni(1)−N(3) 1.949(2)
Å]. For these latter Ni−N distances, the Ni−NMe2 distance is
consistently longer than the Ni−Nheterocycle distance. All three
complexes show similar Ni−Cl distances (∼2.2 Å), implying
very similar trans influence to the amido nitrogens of the ligand
frameworks.
c
8
d
9
e
10
f
11
12
13
39
35
57
87
4c
4c
4c
g
14
g
15
a
Conditions unless otherwise specified: heterocycle (1.006 mmol),
alkyl halide (1.509 mmol), LiOtBu (1.06 mmol), solvent (2.0 mL); oil
bath set to 140 °C, 16 h. GC yield; average of two runs. In the
presence of 100 equiv of elemental Hg. In the presence of 500 equiv
b
c
d
e
f
of elemental Hg. Reaction mixture filtered after 1 h. In the presence
g
of added TEMPO. With 0.2 equiv of NaI.
Comparing all four precatalysts, the 6-methyl substituted
quinolinyl congener 6, a direct analogue of B,10 was found to
give the highest yield (61%, run 4) in the direct alkylation of
benzothiazole (H1) with iodooctane (A1) using 5 mol %
catalyst loading, 1 equiv of LiOtBu, 1,4-dioxane solvent and 16
h reaction time at 140 °C. As noted, complex B has been
previously shown to be highly competent in the coupling of
alkyl halides with sulfur-containing benzothiazoles.10 Phenan-
thridinyl-based analogues 4a−c were competitive, but gave
slightly lower yields (42−49%; runs 1−3) under these
Catalytic Activity. We then screened the prepared
coordination complexes for reactivity in the direct C−H
activation of azoles using unactivated alkyl halides (Table 1).
C
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a
Table 2. Scope for 4c Catalyzed Alkylations of Benzoxazole with Alkylbromides
a
Conditions: heterocycle (1.006 mmol), 1-bromoalkane (1.509 mmol), LiOtBu (1.060 mmol), solvent (2.0 mL); 140 °C, 16 h; GC yield in
parentheses.
Figure 4. (a) Cyclic voltammograms (solid line) and corresponding differential pulse voltammograms (dashed line) of 4a−c and 6 in CH2Cl2 with
0.10 M [nBu4N][PF6] as the supporting electrolyte, glassy carbon working electrode. CV scan rates were 100 mV/s. Potentials are referenced vs the
FcH0/+ redox couple (FcH = ferrocene). (b) Normalized DPVs of 4a−c and 6.
conditions. In the coupling of alkyl halides with the oxygen-
containing starting material benzoxazole (H2), 4c began to
significantly outperform all other precatalysts. Yields of the
coupled product were found to reach as high as 87% using
octyl chloride (A3) in the presence of NaI.
pathway proposed by Punji and co-workers, which involves on-
cycle high-valent Ni(III) and Ni(IV) intermediates.20 Accord-
ingly, we collected electrochemical data for the precatalysts
screened in this work in an attempt to correlate catalytic
behavior with redox potentials.
Having observed promising reactivity with benzannulated
coordination complex 4c, we next explored a brief substrate
scope for 4c as precatalyst (Table 2). The reaction conditions
were found to be amenable to the coupling of benzoxazole
with a variety of alkyl halides bearing carbazole (P3), ester
(P4), aryl (P5), arylether (P6), thioether (P7), alkenyl (P8),
and aliphatic (P9, P10) substituents. The catalysis mediated by
4a−c and 6 likely proceeds analogously to what has been
observed by Punji and co-workers using their related
quinolinyl-supported precatalyst B.10,20 In support of this,
participation of heterogeneous particulate nickel generated via
catalyst decomposition appears to be minimal, as catalysis in
the presence of added Hg (Table 1, runs 8−9) and following
filtration (run 10) proceeded unimpeded. On the other hand,
addition of the radical scavenger TEMPO (2,2,6,6-tetrame-
thylpiperidine 1-oxyl) completely shut down reactivity (run
11). This is consistent with the homogeneous radical rebound
Cyclic voltammograms (CVs) and differential pulse
voltammograms (DPVs) of precatalysts 4a−c and 6 were
taken in dichloromethane solution with 0.1 M [nBu4N][PF6]
as the supporting electrolyte (Figure 4). A quasi-reversible
anodic wave between 0 and +0.3 V (vs FcH0/+; FcH =
ferrocene) is observed for each compound, consistent with an
overall 1e− oxidation. All compounds exhibit broad, irreversible
reductions that overlap with the edge of the solvent window,
making comparisons of these cathodic features within the
series challenging. Accordingly, we focus here on the anodic
electrochemical events. The oxidation potentials and peak
parameters for the complexes are tabulated in Table 3. The
electron releasing tBu group of 4b shifts the oxidation potential
to more accessible potentials compared with methyl analogues
4a and 6. In comparison, an anodically shifted oxidation is
observed for 4c, consistent with the presence of an electron
withdrawing substituent on the ligand. The alkylation pathway
D
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spectrometers. 1H and 13C{1H} NMR spectra were referenced to
residual solvent peaks. Elemental analyses were performed by
Microanalytical Service Ltd., Delta, BC, Canada, and at the University
of Manitoba using a PerkinElmer 2400 Series II CHNS/O Elemental
Analyzer. High-resolution mass spectra were recorded using a Bruker
microOTOF-QIII.
Table 3. Electrochemical Parameters for Ni Complexes
a
compound
E1/2 (V)
Δptp (mV)
i
red/iox
4b
4a
6
0.01
0.07
0.16
0.26
133
143
91
1.17
1.04
0.87
0.92
Synthesis of 4-Nitro-2-trifluoromethylphenanthridine (1c).
A 500 mL Teflon-stoppered flask was charged with Pd(PPh3)4 (1.04
g, 0.90 mmol), and 50 mL of 1,2-dimethoxyethane (DME). After
stirring briefly to mix, 2-iodo-6-nitro-4-trifluoromethylaniline (10.0 g,
30.1 mmol), 2-formylphenylboronic acid (4.97 g, 33.1 mmol), and an
additional 70 mL of DME were added, followed by Na2CO3 (9.6 g,
90.4 mmol) dissolved in 100 mL of degassed water. The flask was
then sealed and the mixture stirred vigorously for 6 h in an oil bath set
to 130 °C. The flask was then allowed to cool, charged with 130 mL
of 2 M HCl, and refluxed for additional 2 h. The reaction mixture was
cooled, neutralized with NaOH, and pumped to dryness. The residue
was then taken up in dichloromethane (100 mL) and washed with
brine (3 × 100 mL). The organic layer was separated, dried over
Na2SO4 and volatiles removed. Column chromatography on neutral
alumina gave a pale yellow solid (Rf = 0.41; 1:5 EtOAc/hexanes).
Isolated yield = 7.86 g (89%). 1H NMR (CDCl3, 300 MHz, 22 °C) δ
9.48 (s, 1H; CArH), 9.01 (s, 1H; CArH), 8.67 (d, 1H, JHH = 8.0 Hz;
CArH), 8.18 (overlapped m, 2H; CArH), 8.05 (ddd, 1H, JHH = 8.4, 7.2,
1.4 Hz; CArH), 7.92 ppm (m, 1H; CArH). 13C{1H} NMR (CDCl3,
125 MHz, 22 °C):δ 158.0 (CAr), 149.8 (CAr), 137.5 (CAr), 133.1
(CAr), 131.2 (q, CAr), 130.0 (CAr), 129.8 (CAr), 128.4 (CAr), 126.9
(CAr), 126.0 (CAr), 124.3 (CAr), 123.2 (q, CF3), 122.3 (CAr), 118.7
ppm (q, CAr). 19F{1H} NMR (CDCl3, 282 MHz, 22 °C) δ −62.03
ppm.
4c
147
a
Δptp = distance measured from “peak-to-peak”, showing the
separation in mV between the peak maximum of the oxidation and
corresponding reduction.
catalyzed by B proposed by Punji and co-workers20 invokes a
one-electron Ni(II/III) pathway that occurs by oxidative
addition of alkyl iodide via iodine atom transfer (IAT).26 The
lack of reactivity in the presence of the radical trap TEMPO
(Table 1, run 11) supports a similar mechanism here.
Oxidative addition by (inner-sphere) electron-transfer mech-
anisms are typically associated with metal centers with
coordinative unsaturation to bind a substrate, and sufficiently
cathodic electrochemical potentials to reduce the organic
electrophile.27 The observation of higher yields for the most
electrophilic congener 4c with a pronounced anodic shift to its
oxidation event suggests that the elevated π-acidicity of the
CF3-substituted phenanthridine ligand framework18 may be
key in this context.
CONCLUSION
■
4-Amino-2-trifluoromethylphenanthridine (2c). To a stirred
solution of 1c (6.02 g, 20.5 mmol) in methanol (100 mL), Zn dust
(2.68 g, 41.1 mmol), and hydrazinium monoformate solution (54 mL;
prepared by slowly neutralizing equal molar amounts of hydrazine
hydrate (50 mL) with 85% formic acid (4 mL) in an ice−water bath)
were added and stirred vigorously at 60 °C. The resulting green
suspension was cooled and filtered over Celite. The filtrate was
pumped dry, the residue dissolved in dichloromethane (100 mL), and
washed with brine (3 × 60 mL). The organic layer was separated,
dried over Na2SO4, and dried to leave a brown solid. Column
chromatography on neutral alumina gave a pale-yellow solid (Rf =
In conclusion, we have demonstrated that the introduction of
benzannulated phenanthridine ligands supporting Ni(II)
coordination complexes maintain the high activity observed
in the C−H alkylation of azoles observed with quinoline
congeners,10 for both benzoxazole and benzothiazole. The
synthetic route to the N^N(H)^N proligand frameworks 3a−c
allows for facile incorporation of different substituents, whose
electron-releasing/electron-withdrawing properties can be
quantified in terms of the redox properties of their Ni
complexes in solution. Comprehensive mechanistic studies,
including investigating correlation of catalytic activity to the π-
acidity of the benzannulated phenanthridine ligand frame-
works,18 and expansion of the scope of C−C bond forming
reactions to other substrate classes is presently underway.
1
0.43; 1:5 EtOAc/hexane). Isolated yield = 3.74 g (86%). H NMR
(CDCl3, 300 MHz, 22 °C) δ 9.15 (s, 1H; CArH), 8.50 (d, 1H, JHH
=
8.3; CArH), 8.07 (s, 1H; CArH), 8.01 (dd, 1H, JHH = 8.0, 1.3 Hz;
CArH), 7.83 (app t, 1H, JHH = 8.4, 7.0 Hz; CArH), 7.70 (app t, 1H, JHH
= 8.1, 7.0; CArH), 7.13 (d, 1H, JHH = 1.8 Hz; CArH), 5.22 ppm (br s,
2H; NH). 13C{1H} NMR (CDCl3, 75 MHz, 22 °C) δ 152.2 (CAr),
145.6 (CAr), 134.5 (CAr), 132.7 (CAr), 131.3 (q, CAr), 128.9 (CAr),
128.1 (CAr), 126.9 (CAr), 124.3 (CAr), 122.5 (CAr), 107.9 (q, CF3),
106.7 ppm (q, CAr). 19F{1H} NMR (CDCl3, 282 MHz, 22 °C) δ
−62.28 ppm.
EXPERIMENTAL SECTION
■
Unless otherwise specified, air sensitive manipulations were carried
either in an N2-filled glovebox or using standard Schlenk techniques
under Ar. (N,N-Dimethyl)-para-toluidine (Sigma-Aldrich), 2-formyl-
phenyl boronic acid (AK Scientific), N-iodosuccinimide (AK
Scientific), N-bromosuccinimide (Alfa Aesar), Pd(PPh3)4 (Sigma-
Aldrich), Pd2(dba)3 (Sigma-Aldrich), 2-nitro-4-(trifluoromethyl)-
aniline (Sigma-Aldrich), (1,1′-diphenylphosphino)ferrocene (dppf,
Sigma-Aldrich), ( )-2,2′-bis(diphenylphosphino)-1,1′-binapthalene
(rac-BINAP, Sigma-Aldrich), Na2CO3 (Alfa Aesar), trifluoroacetic
acid (Sigma-Aldrich), sodium tert-pentoxide (NaOtAm, Sigma-
Aldrich), sodium tert-butoxide (NaOtBu, Sigma-Aldrich), zinc (Alfa
Aesar), hydrazine hydrate (Sigma-Aldrich), formic acid (Alfa Aesar),
NiCl2·6H2O (Alfa Aesar), and all reagents used in precursor synthesis
and catalytic trials were purchased and used without any further
purification. (2-Bromo-4,N,N-trimethyl)aniline,28 (8-amino-4-
methyl)quinoline,29 (4-amino-2-methyl)phenanthridine (2a),15 (4-
amino-2-tert-butyl)phenanthridine (2b),18 and 2-iodo-6-nitro-4-tri-
fluoromethylaniline30 were synthesized according to published
procedures. Organic solvents were dried and distilled using
appropriate drying agents, while distilled water was degassed prior
to use. Multinuclear 1D and 2D NMR spectra were recorded on
Bruker Avance 300 MHz or Bruker Avance III 500 MHz
Synthesis of MeQuinNN(H)NMe2 (5).
A 350 mL Teflon-stoppered flask was charged with Pd2(dba)3 (1.91 g,
2.09 mmol), dppf (2.69 g, 4.69 mmol), and toluene (30 mL). After
stirring briefly, (8-amino-4-methyl)quinoline29 (4.15 g, 26.1 mmol),
(2-bromo-4,N,N-trimethyl)aniline28 (6.70 g, 31.3 mmol) were
combined with an additional 90 mL of toluene, followed by NaOtAm
(4.30 g, 39.1 mmol). The mixture was then stirred vigorously for 72 h
in an oil bath set to 130 °C. After cooling the flask and removing the
volatiles, the residue was taken up in dichloromethane (120 mL), and
the resulting suspension filtered over Celite and dried. Column
chromatography gave a yellow oil which solidified on standing
E
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(neutral alumina; 1:10 EtOAc/hexane; Rf = 0.5). Isolated yield = 8.23
g (74%). 1H NMR (CDCl3, 500 MHz, 22 °C) δ 8.76 (dd, 1H; JHH
Synthesis of CF3PhenNN(H)NMe2 (3c).
=
4.2, 1.7 Hz, C1H), 8.65 (brs, 1H; NH), 8.01 (dd, 1H, JHH = 8.3, 1.7
Hz; C3H), 7.50 (d, 1H, JHH = 1.9 Hz; C16H), 7.46 (d, 1H, JHH = 1.7
Hz; C7H), 7.38 (dd, 1H, JHH = 8.2, 4.2 Hz; C2H), 7.06 (d, 1H, JHH
=
8.0 Hz; C13H), 7.00 (s, 1H, C5H), 6.81 (m, 1H, JHH = 8.0, 2.0 Hz;
C14H), 2.72 (s, 6H; N(C(18,19)H3)2), 2.51 (s, 3H; C10H3), 2.38 (s, 3H,
C17H3). 13C{1H} NMR (CDCl3, 125 MHz, 22 °C) δ 146.7(C1), 142.7
(C12), 139.7 (C8), 138.1 (C9), 137.3 (C6), 136.0 (C11), 136.0 (C3),
132.7 (C15), 129.1 (C4), 122.1 (C14), 121.6 (C2), 119.2 (C13), 118.5
(C16), 115.5 (C5), 109.6 (C7), 44.1 (N(C18,19)2), 22.5 (C10), 21.4 ppm
(C17).
An identical procedure to the synthesis of 5 was employed, using
Pd2(dba)3 (0.20 g, 0.22 mmol), dppf (0.27 g, 0.49 mmol), 2c (1.16 g,
4.42 mmol), (2-bromo-4,N,N-trimethyl)aniline28 (1.14 g, 5.30 mmol)
and NaOtAm (0.73 g, 6.63 mmol). Column chromatography on
neutral alumina gave a yellow solid (1:10 EtOAc/hexane; Rf = 0.5).
Isolated yield = 1.50 g (85%) 1H NMR (CDCl3, 300 MHz, 22 °C) δ
9.30 (s, 1H; C1H), 8.89 (brs, 1H; NH), 8.63 (d, 1H, JHH = 8.3 Hz;
C6H), 8.18 (s, 1H; C13H), 8.11 (d, 1H, JHH = 8.0 Hz; C3H), 7.92 (t,
1H, JHH = 8.3, 6.9 Hz; C5H), 7.83−7.73 (m, 2H; C4H, C11H), 7.46 (s,
1H, C20H) 7.07 (d, 1H, JHH = 8.0, Hz; C17H), 6.87 (d, 1H, JHH = 8.2;
C18H), 2.72 (s, 6H; N(C22, 23H3)2), 2.37 ppm (s, 3H; C21H3).
13C{1H} NMR (CDCl3, 125 MHz, 22 °C) δ 152.3 (C1), 143.2 (C10),
141.9 (C16), 135.2 (C15), 135.1 (C9), 133.1 (C2), 133.0 (C19), 131.5
(C5), 129.6 (C14, quartet), 129.0 (C3), 128.2 (C4), 127.1 (C12), 125.8
(C8), 123.7 (C7), 123.3 (C18), 122.6 (C6), 119.5 (C17), 119.4 (C20),
108.0 (C13), 104.2 (C11), 44.14 (N(C22, 23)2), 21.4 ppm (C21).
19F{1H} NMR (CDCl3, 282 MHz, 22 °C) δ −62.37 ppm (s, 3F;
CF3).
Synthesis of MePhenNN(H)NMe2 (3a).
An identical procedure to the synthesis of 5 was employed, using
Pd2(dba)3 (0.51 g, 0.55 mmol), dppf (0.67 g, 1.21 mmol), 2a (2.30 g,
11.0 mmol), (2-bromo-4,N,N-trimethyl)aniline28 (2.83 g, 13.3 mmol)
and NaOtAm (1.82 g, 16.6 mmol). Column chromatography on
neutral alumina gave a yellow solid (1:10 EtOAc/hexane; Rf = 0.5).
Isolated yield = 1.34 g (97%). 1H NMR (CDCl3, 500 MHz, 22 °C) δ
9.18 (s, 1H; C1H), 8.72 (br s, 1H; NH), 8.61 (d, 1H, JHH = 8.2 Hz;
C6H), 8.06 (d, 1H, JHH = 7.7 Hz; C3H), 7.84 (dd, 1H, JHH = 8.4, 7.0
Hz; C5H), 7.78 (s, 1H; C20H), 7.71 (dd, 1H, JHH = 8.0, 7.0 Hz; C4H),
7.55 (s, 1H; C13H), 7.51(s, 1H; C11H), 7.07 (d, 1H, JHH = 8.0 Hz;
C17H), 6.82 (dd, 1H, JHH = 8.0, 1.9 Hz; C18H), 2.74 (s, 6H;
N(C22,23H3)2), 2.60 (s, 3H; C14H3), 2.38 ppm (s, 3H; C21H3).
13C{1H} NMR (CDCl3, 75 MHz, 22 °C) δ 149.5 (C1), 142.7 (C16),
140.7 (C10), 137.7 (C12), 136.1 (C15), 132.8 (C9), 132.7 (C19), 132.6
(C2), 130.5 (C5), 128.6 (C3), 127.3 (C4), 127.1 (C8), 124.7 (C7),
122.4 (C6), 122.0 (C18), 119.1 (C17), 118.7 (C11), 111.0 (C20), 110.5
(C13), 44.1 (N(C22,23)2), 22.8 (C14), 21.3 ppm (C21).
Synthesis of MeQuinNNNMe2-Ni (6).
To a stirred solution of compound 5 (1.01 g, 3.43 mmol) in 30 mL of
dichloromethane, NiCl2·6H2O (0.86g, 3.60 mmol), and NaOtBu
(0.35 g, 3.60 mmol) were added, and the mixture stirred vigorously at
65 °C for 18 h. The resulting red suspension was allowed to cool, and
the volatiles removed in vacuo. The residue was then washed with
diethyl ether (3 × 15 mL) to isolate red solid. The compound is
further purified by redissolving in DCM and passed through Celite.
Isolated yield = 1.17 g (89%). 1H NMR (CDCl3, 500 MHz, 22 °C) δ
8.46 (d, 1H, JHH = 5.0 Hz; C1H), 7.98 (dd, 1H, JHH = 8.2, 1.5 Hz;
Synthesis of tBuPhenNN(H)NMe2 (3b).
C3H), 7.34 (s, 1H; C16H), 7.24 (s, 1H; C7/5H), 7.17 (dd, 1H, JHH
=
8.2, 5.3 Hz; C2H), 6.96 (d, 1H, JHH = 8.1; C13H), 6.67 (s, 1H; C5/7H),
6.47−6.40 (m, 1H; C14H), 3.02 (s, 6H; N(C19,18H3)2), 2.48 (s, 3H;
C10H3), 2.36 ppm (s, 3H; C17H3). 13C{1H} NMR (CDCl3, 125 MHz,
22 °C) δ 149.5 (C1), 147.9 (C8), 147.2 (C11), 146.1 (C9), 145.2 (C12),
139.6 (C6), 138.5 (C15), 137.7 (C3), 129.5 (C4), 120.9 (C2), 119.9
(C13), 117.9 (C14), 115.5 (C16), 112.5 (C5/7), 112.3 (C5/7), 51.9
(N(C18, 19)2), 22.6 (C10), 21.7 ppm (C17). Anal. Calcd for
C19H20ClN3Ni: C, 59.35; H, 5.24. Found: C, 59.07; H, 5.25.
Synthesis of MePhenNNNMe2-Ni (4a).
An identical procedure to the synthesis of 5 was employed, using
Pd2(dba)3 (0.55 g, 0.60 mmol), dppf (0.73 g, 1.32 mmol), 2b (3.0 g,
11.9 mmol), (2-bromo-4,N,N-trimethyl)aniline28 (2.87 g, 13.4
mmol), and NaOtAm (1.98 g, 17.9 mmol). Column chromatography
on neutral alumina gave a yellow solid (1:10 EtOAc/hexane; Rf =
1
0.5). Isolated yield = 4.18 g (91%) H NMR (CDCl3, 300 MHz, 22
°C) δ 9.18 (s, 1H; C1H), 8.73 (brs, 1H; NH), 8.65 (d, 1H, JHH = 8.4
Hz; C6H), 8.11−7.97 (m, 2H; C3H, C23H), 7.96−7.80 (m, 2H; C5H,
C13H), 7.69 (m, 1H; C4H), 7.54 (s, 1H; C11H), 7.08 (dd, 1H, JHH
=
8.0, 2.5 Hz; C20H), 6.80 (dd, 1H, JHH = 8.1, 2.2 Hz; C21H), 2.78 (s,
6H; N(C25, 26H3)2), 2.37 (s, 3H; C24H3), 1.52 ppm (s, 9H;
(C15,16,17H3)3). 13C{1H} NMR (CDCl3, 75 MHz, 22 °C) δ 150.6
(C12), 150.0 (C1), 142.3 (C19), 140.1 (C10), 136.6 (C18), 133.2 (C9),
133.1 (C2), 132.9 (C22), 130.6 (C5), 128.8 (C3), 127.2 (C4), 127.0
(C8), 124.3 (C7), 122.4 (C6), 121.5 (C21), 119.3 (C20), 117.4 (C11),
108.9 (C23), 107.4 (C13), 44.2 (N(C25, 26)2), 35.7 (C14), 31.7
(C15, 16, 17), 21.5 ppm (C24).
An identical procedure to the synthesis of 6 was employed, using 3a
(1.14 g, 3.33 mmol), NiCl2·6H2O (0.81 g, 3.42 mmol), and NaOtBu
(0.34 g, 3.50 mmol) in 15 mL of dichloromethane. Isolated yield =
F
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Organometallics XXXX, XXX, XXX−XXX

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Article
1
1.32 g (91%). H NMR (CDCl3, 300 MHz, 22 °C) δ 8.88 (s, 1H;
C1H), 8.39 (d, 1H, JHH = 8.4 Hz; C6H), 7.88 (d, 1H, JHH = 8.1 Hz;
C3H), 7.83 (t, 1H, JHH = 7.8 Hz; C5H), 7.61 (t, 1H, JHH = 7.6 Hz;
C4H), 7.37 (s, 1H; C20H), 7.31 (s, 1H; C11H), 7.28 (s, 1H; C13H),
6.96 (d, 1H, JHH = 8.1 Hz; C17H), 6.43 (d, 1H, JHH = 7.8 Hz; C18H),
3.05 (s, 6H; N(C22, 23H3)2), 2.57 (s, 3H; C14H3), 2.36 ppm (s, 3H;
C21H3). 13C{1H} NMR (CDCl3, 125 MHz, 22 °C) δ 153.9 (C1),
148.5 (C10), 147.3 (C15), 145.0 (C16), 140.0 (C9), 139.6 (C12), 138.3
(C19), 132.7 (C2), 132.4 (C5), 129.6 (C3), 127.5 (C4), 126.0 (C8),
125.2 (C7), 122.2 (C6), 119.8 (C17), 117.6 (C18), 115.4 (C20), 112.2
(C11), 108.3 (C13), 51.8 (N(C22, 23)2), 22.8 (C14) and 21.6 (C21). Anal.
Calcd for C23H22ClN3Ni: C, 63.57; H, 5.10. Found: C, 63.60; H, 5.21.
Synthesis of tBuPhenNNNMe2-Ni (4b).
software.31 Structure solution and refinement was carried out using
XS, XT and XL software, embedded within the Bruker SHELXTL
suite.32 For each structure, the absence of additional symmetry was
confirmed using ADDSYM incorporated in the PLATON program.33
CCDC Nos. 1985563−1985568 contain the supplementary crystallo-
graphic data for this paper. The data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/structures.
Crystal Structure Data for 3a (CCDC No. 1985568). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
saturated CHCl3 solution of the compound at room temperature.
Crystal structure parameters: C23H23N3 341.44 g/mol, monoclinic,
space group P21/c; a = 17.2243(11) Å, b = 14.7273(9) Å, c =
7.1219(5) Å, α = 90°, β = 99.910(3)°, γ = 90°, V = 1779.6(2) Å3; Z =
4, ρcalcd = 1.274 g cm−3; crystal dimensions 0.266 × 0.200 × 0.150
mm3; θmax = 39.509°; 114196 reflections, 10645 independent (Rint
=
0.0597), intrinsic phasing; absorption coeff (μ = 0.076 mm−1),
absorption correction semiempirical from equivalents (SADABS);
2
refinement (against Fo ) with SHELXTL V6.1, 239 parameters, 0
restraints, R1 = 0.0553 (I > 2σ) and wR2 = 0.1722 (all data), GoF =
1.046, residual electron density 0.620/−0.610 e Å−3.
Crystal Structure Data for 3b (CCDC No. 1985565). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
saturated CHCl3 solution of the compound at room temperature.
Crystal structure parameters: C26H29N3 383.52 g/mol, trigonal, space
group P32; a = 10.2023(3) Å, b = 10.2023(3) Å, c = 17.7612(6) Å, α
= 90°, β = 90°, γ = 120°, V = 1061.03(11) Å3; Z = 3, ρcalcd = 1.193 g
cm−3; crystal dimensions 0.100 × 0.050 × 0.050 mm3; θmax = 30.499°;
37488 reflections, 6534 independent (Rint = 0.0833), intrinsic
phasing; absorption coeff (μ = 0.070 mm−1), absorption correction
An identical procedure to the synthesis of 6 was employed, using 3b
(1.01 g, 2.60 mmol), NiCl2·6H2O (0.65 g, 2.74 mmol), and NaOtBu
(0.26 g, 2.74 mmol) in 15 mL of dichloromethane. Isolated yield =
1
1.17 g (93%). H NMR (CDCl3, 500 MHz, 22 °C) δ 8.93 (s, 1H;
C1H), 8.51 (d, 1H, JHH = 8.3 Hz; C6H), 7.94 (d, 1H, JHH = 8.1 Hz;
C3H), 7.88 (t, 1H, JHH = 8.1 Hz; C5H), 7.64 (m, 2H; C4, 11/13H), 7.55
(s, 1H; C11/13H), 7.40 (s, 1H; C23H), 6.98 (d, 1H, JHH = 8.2 Hz;
C20H), 6.43 (d, 1H, JHH = 8.2 Hz; C21H), 3.05 (s, 6H; N(C25, 26H3)2),
2.36 (s, 3H; C24H3) and 1.49 ppm (s, 9H; (C15, 16, 17H3)3). 13C{1H}
NMR (CDCl3, 125 MHz, 22 °C) δ 154.4 (C1), 152.9 (C12), 148.4
(C10), 147.5 (C18), 145.2 (C19), 140.1 (C9), 138.5 (C22), 133.4 (C2),
132.6 (C5), 129.9 (C3), 127.7 (C4), 126.3 (C8), 125.0 (C7), 122.3
(C6), 120.0 (C20), 117.5 (C21), 115.4 (C23), 109.4 (C11/13), 104.7
(C11/13), 51.9 (N(C25, 26)2), 35.7 (C15, 16, 17)3), 31.8 (C14), 21.9 ppm
(C24). Anal. Calcd for C26H28ClN3Ni: C, 65.51; H, 5.92. Found: C,
65.35; H, 6.03.
2
semiempirical from equivalents (SADABS); refinement (against Fo )
with SHELXTL V6.1, 269 parameters, 1 restraints, R1 = 0.0533 (I >
2σ) and wR2 = 0.1243 (all data), GoF = 1.032, residual electron
density 0.294/−0.245 e Å−3.
Crystal Structure Data for 3c (CCDC No. 1985563). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
CHCl3 solution of the compound at room temperature. Crystal
structure parameters: C23H20F3N3 395.42 g/mol, triclinic, space group
̅
P1; a = 7.8443(4) Å, b = 9.5831(4) Å, c = 13.4612(6) Å, α =
Synthesis of CF3PhenNNNMe2-Ni (4c).
89.4932(18)°, β = 78.5285(18)°, γ = 87.8849(19)°, V = 991.02(8)
Å3; Z = 2, ρcalcd = 1.325 g cm−3; crystal dimensions 0.280 × 0.150 ×
0.040 mm3; θmax = 27.721°; 23306 reflections, 4645 independent (Rint
= 0.0560), intrinsic phasing; absorption coeff (μ = 0.099 mm−1),
absorption correction semiempirical from equivalents (SADABS);
2
refinement (against Fo ) with SHELXTL V6.1, 265 parameters, 0
restraints, R1 = 0.0793 (I > 2σ) and wR2 = 0.2179 (all data), GoF =
1.050, residual electron density 1.031/−0.771 e Å−3.
Crystal Structure Data for 4a (CCDC No. 1985564). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
CHCl3 solution of the compound at room temperature. Crystal
structure parameters: C23H22Cl1N3Ni1 434.59 g/mol, triclinic, space
An identical procedure to the synthesis of 6 was employed, using 3c
(1.80 g, 4.56 mmol), NiCl2·6H2O (1.14 g, 4.77 mmol), and NaOtBu
(0.46 g, 4.79 mmol) in 15 mL of dichloromethane. Isolated yield =
1
̅
group P1; a = 6.9170(4) Å, b = 11.9707(8) Å, c = 12.3017(11) Å, α =
1.86 g (83%). H NMR (CDCl3, 500 MHz, 22 °C) δ 9.10 (s, 1H;
72.668(3)°, β = 82.739(3)°, γ = 89.465(3)°, V = 964.12(11) Å3; Z =
2, ρcalcd = 1.497 g cm−3; crystal dimensions 0.200 × 0.100 × 0.030
C1H), 8.48 (d, 1H, JHH = 8.3 Hz; C6H), 8.10−7.90 (m, 2H; C3, 5H),
7.84−7.56 (m, 3H; C4, 11, 13H), 7.36 (s, 1H; C20H), 7.01 (d, 1H, JHH
= 8.2 Hz; C17H), 6.52 (d, 1H, JHH = 8.2 Hz; C18H), 3.06 (s, 6H;
N(C22,23H3)2), and 2.37 (s, 3H; C21H3). 13C{1H} NMR (CDCl3, 125
MHz, 22 °C) δ 156.1 (C1), 149.0 (C10), 146.5 (C15), 145.3 (C16),
142.6 (C9), 138.8 (C19), 133.4 (C5), 132.9 (C2), 131.1 (C14, quartet),
130.1 (C3), 128.5 (C4), 126.1 (C12), 125.5 (C8), 123.4 (C7), 122.4
(C6), 120.1 (C17), 119.0 (C18), 115.8 (C20), 105.9 (C13), 105.1 (C11),
52.0 (N(C22, 23)2), 21.7 ppm (C21). 19F{1H} NMR (CDCl3, 470
MHz, 22 °C) δ −62.27 ppm (s, 3F; CF3). Anal. Calcd for
C23H19ClF3N3Ni: C, 56.54; H, 3.92. Found: C, 56.33; H, 3.63.
X-ray Crystallography. X-ray crystal structure data was using
collected from multifaceted crystals of suitable size and quality
selected from a representative sample of crystals of the same habit
using an optical microscope. In each case, crystals were mounted on
MiTiGen loops with data collection carried out in a cold stream of
nitrogen (150 K; Bruker D8 QUEST ECO; Mo Kα radiation). All
diffractometer manipulations were carried out using Bruker APEX3
mm3; θmax = 27.979°; 39487 reflections, 4613 independent (Rint
=
0.0453), intrinsic phasing; absorption coeff (μ = 1.159 mm−1),
absorption correction semiempirical from equivalents (SADABS);
2
refinement (against Fo ) with SHELXTL V6.1, 257 parameters, 0
restraints, R1 = 0.0424 (I > 2σ) and wR2 = 0.1011 (all data), GoF =
1.137, residual electron density 0.806/−0.637 e Å−3.
Crystal Structure Data for 4b (CCDC No. 1985566). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
CHCl3 solution of the compound at room temperature. Crystal
structure parameters: C26H28Cl1N3Ni1 476.67 g/mol, monoclinic,
space group P21/c; a = 14.9402(10) Å, b = 16.7884(11) Å, c =
8.9308(6) Å, α = 90°, β = 98.074(3)°, γ = 90°, V = 2217.8(3) Å3; Z =
4, ρcalcd = 1.428 g cm−3; crystal dimensions 0.200 × 0.150 × 0.050
mm3; θmax = 33.129°; 68772 reflections, 7415 independent (Rint
=
0.0419), intrinsic phasing; absorption coeff (μ = 1.014 mm−1),
absorption correction semiempirical from equivalents (SADABS);
G
https://dx.doi.org/10.1021/acs.organomet.0c00161
Organometallics XXXX, XXX, XXX−XXX

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pubs.acs.org/Organometallics
Article
2
refinement (against Fo ) with SHELXTL V6.1, 286 parameters, 0
restraints, R1 = 0.0453 (I > 2σ) and wR2 = 0.0915 (all data), GoF =
1.054, residual electron density 0.647/−0.642 e Å−3.
Gabrielle Wilson − Department of Chemistry and the Manitoba
Institute of Materials, University of Manitoba, Winnipeg,
Manitoba R3T 2N2, Canada
Crystal Structure Data for 6 (CCDC No. 1985567). X-ray quality
crystals were grown following diffusion of diethyl ether vapor into a
CHCl3 solution of the compound at room temperature. Crystal
structure parameters: C19H20Cl1N3Ni1 384.54 g/mol, triclinic, space
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.organomet.0c00161
̅
group P1; a = 9.8825(13) Å, b = 14.352(3) Å, c = 24.736(4) Å, α =
Notes
90.844(12)°, β = 94.338(10)°, γ = 102.995(13)°, V = 3406.9(10) Å3;
Z = 8, ρcalcd = 1.499 g cm−3; crystal dimensions 0.300 × 0.200 × 0.050
The authors declare no competing financial interest.
mm3; θmax = 30.679°; 97358 reflections, 20976 independent (Rint
=
0.1012), intrinsic phasing; absorption coeff (μ = 1.300 mm−1),
ACKNOWLEDGMENTS
■
absorption correction semiempirical from equivalents (SADABS);
The following sources of funding are gratefully acknowledged:
Natural Sciences Engineering Research Council of Canada for
a USRA (GW) and a Discovery Grant to DEH (RGPIN-2014-
03733); the Canadian Foundation for Innovation and
Research Manitoba for an award in support of an X-ray
diffractometer (CFI #32146); and the University of Manitoba
for GETS support (PM, JDB). We are also grateful to Bin
Huang for assistance collecting spectra of 2c.
2
refinement (against Fo ) with SHELXTL V6.1, 881 parameters, 0
restraints, R1 = 0.0601 (I > 2σ) and wR2 = 0.1253 (all data), GoF =
1.021, residual electron density 0.770/−0.722 e Å−3.
Representative Procedure for Catalytic Trials. To a 50 mL
Teflon stoppered flask catalyst 4c (0.012 g, 0.05 mmol), LiOtBu
(0.081 g, 1.01 mmol), benzoxazole (H2; 0.12 g, 1.01 mmol), and 1-
iodooctane (A1; 0.291 g, 0.75 mmol), added 1,4-dioxane (2.0 mL)
inside an N2-filled glovebox. The resulting reaction mixture was
stirred in a preheated oil bath set to 140 °C for 16 h. An aliquot (10
μL) of the reaction mixture diluted with 1 mL acetone was injected to
GC instrument to analyze the products. GC yields of the products
were obtained from the calibration curves plotted for pure reactants
and products, with biphenyl as an internal standard, and are reported
as an average of two runs.
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ASSOCIATED CONTENT
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sı
* Supporting Information
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AUTHOR INFORMATION
■
Corresponding Author
David E. Herbert − Department of Chemistry and the
Manitoba Institute of Materials, University of Manitoba,
Winnipeg, Manitoba R3T 2N2, Canada; orcid.org/0000-
0001-8190-2468; Email: david.herbert@umanitoba.ca
Authors
Pavan Mandapati − Department of Chemistry and the
Manitoba Institute of Materials, University of Manitoba,
Winnipeg, Manitoba R3T 2N2, Canada; orcid.org/0000-
0002-3686-4850
Jason D. Braun − Department of Chemistry and the Manitoba
Institute of Materials, University of Manitoba, Winnipeg,
Manitoba R3T 2N2, Canada; orcid.org/0000-0002-5850-
8048
Baldeep K. Sidhu − Department of Chemistry and the
Manitoba Institute of Materials, University of Manitoba,
Winnipeg, Manitoba R3T 2N2, Canada; orcid.org/0000-
0002-2016-6601
(14) Ren, P.; Salihu, I.; Scopelliti, R.; Hu, X. Copper-Catalyzed
Alkylation of Benzoxazoles with Secondary Alkyl Halides. Org. Lett.
2012, 14, 1748−1751.
(15) Mandapati, P.; Giesbrecht, P. K.; Davis, R. L.; Herbert, D. E.
Phenanthridine-Containing Pincer-like Amido Complexes of Nickel,
Palladium, and Platinum. Inorg. Chem. 2017, 56, 3674−3685.
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Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
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