A Highly Selective Manganese-Catalyzed Synthesis of Imines under Phosphine-Free Conditions

Article abstract of DOI:10.1021/acs.organomet.9b00769

An efficient and highly selective phosphine-free NN-manganese(I) complex catalyst system was developed for the acceptorless dehydrogenative coupling of alcohols with amines to form imines. The coupling reactions underwent at 3 mol % catalyst loading, and a large range of alcohols and amines with diverse functional groups was applied, including challenging diol and diamine. The target imine products were obtained in good to excellent yields. The present work provides an alternative method to construct highly active nonprecious metal complex catalysts based on phosphine-free ligands.

Full text of DOI:10.1021/acs.organomet.9b00769

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
A Highly Selective Manganese-Catalyzed Synthesis of Imines under
Phosphine-Free Conditions
Huining Chai,*,†,∥ Kun Yu,‡,∥ Bo Liu,‡,∥ Weiqiang Tan,† and Guangyao Zhang§
†School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033, People’s Republic of
China
‡School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences; Institute of Materia Medica,
Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250062, People’s Republic of China
§Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, Qingdao University, Qingdao 266071,
People’s Republic of China
S
* Supporting Information
ABSTRACT: An efficient and highly selective phosphine-free NN-
manganese(I) complex catalyst system was developed for the accept-
orless dehydrogenative coupling of alcohols with amines to form imines.
The coupling reactions underwent at 3 mol % catalyst loading, and a
large range of alcohols and amines with diverse functional groups was
applied, including challenging diol and diamine. The target imine
products were obtained in good to excellent yields. The present work
provides an alternative method to construct highly active nonprecious
metal complex catalysts based on phosphine-free ligands.
workers showed the similar PNP ligand-supported manganese
complex D (Scheme 1) can also catalyze this reaction.10 Very
recently, Kempe’s group reported the base-switchable synthesis
of amines or imines from the same alcohol and amine
combinations catalyzed by the versatile PNP-type manganese
complex E (Scheme 1).11 Despite the significance of such
coupling reactions, homogeneous cheap metal complex
catalysts mostly contain posphine ligands that are sensitive to
air and moisture and difficult to be prepared on a large scale.
The development of nonprecious metal complex catalysts
possessing phosphine-free ligands is urgent. Intrigued by these
studies,12 we paid much attention to the complexes bearing
bidentate phosphine-free ligands. During our investigation of
transition-metal complex catalysts, we disclose an efficient and
highly selective phosphine-free NN-manganese(I) complex
catalyst system, which enables the synthesis of imines from
alcohols and amines efficiently and selectively (Scheme 1).
INTRODUCTION
■
Substituted imines and their derivatives are important building
blocks in pharmaceuticals and agricultural chemicals.1 More-
over, imine-based compounds can act as effective ligands in
coordination chemistry to construct versatile transition-metal
complex catalysts for catalysis.2 Typically, imines are
synthesized via the reaction of carbonyl compounds, such as
aldehydes or ketones, with amines.3 Significant progress has
been made in acceptorless dehydrogenation reactions of
alcohols in rencent years. Alcohols can be obtained from
lignocellulose, which is a renewable biomass.4 The catalytic
synthesis of imines by acceptorless dehydrogenative coupling
(ADC) reactions of alcohols with amines is an attractive green
and sustainable route, in which H2 and H2O are produced as
byproducts. In this direction, pioneering work was reported by
Milstein and co-workers5 in 2010, and they used a PNP-
ruthenium pincer complex as the catalyst. Following this
report, several catalytic systems for imine synthesis have been
developed with precious-metal catalysts.6 In 2012, Zhang and
Hanson introduced the first synthesis of imines catalyzed by
the PNP-pincer cobalt complex catalyst A (Scheme 1).7 In
2013, Kumar/Singh et al. employed a Fe-phthalocyanine
complex B (Scheme 1) as the catalyst to synthesize imines
from alcohols and amines.8 Notably, in 2016 Milstein’s group
reported the unprecedented dehydogenative coupling of
alcohols and amines catalyzed by pincer-type Mn-PNP
complex C (Scheme 1).9 Subsequently, Kirchner and co-
RESULTS AND DISCUSSION
■
Synthesis and Characterization of Complexes. Ini-
tially, we prepared two NN-manganese(I) complexes (2a, 2b)
by using ligands 1a, 1b with Mn(CO)5Br in MeOH at room
temperature under a nitrogen atmosphere, giving correspond-
ing Mn complexes 2a and 2b in 85% and 83% yields,
Received: November 10, 2019
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.9b00769
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Scheme 1. Synthesis of Imines by Nonprecious Metal Complex Catalysts
respectively (Scheme 2). The NMR analyses of the ligands and
their complexes are consistent with the compositions. In the
a
Scheme 2. Synthesis of Complexes 2a and 2b
a
Conditions: 1a or 1b (1.0 mmol), Mn(CO)5Br (1.0 mmol), CH3OH
(25 mL), 0.1 M Pa N2, 25 °C, 24 h, 85% (2a), 83% (2b).
13C NMR spectrum, the three coordinating CO groups in
complexes appeared at 222.5, 222.1, and 221.6 ppm for 2a and
at 223.3, 223.0, and 220.6 ppm for 2b. In the infrared spectrum
(IR) of complex 2a, the stretching vibrations of CO ligands
gave rise to bands at 1927 and 2036 cm−1. Similarly, carbonyl
ligands in complex 2b were revealed at 1888 and 2013 cm−1 in
the IR spectral analysis. We attempted to obtain the single
crystals of complex 2a for the X-ray structural analysis, but no
success was achieved. To our delight, the molecular structure
of methyl-substituted complex 2b was confirmed by the X-ray
single-crystal crystallographic determination (Figure 1, see
Supporting Information for details). The structure of complex
2b exhibits a distorted octahedral geometry, and the central
manganese atom of complex 2b is surrounded by bidentate
NN ligand 1b, three CO groups, and a bromo atom
positioning trans to one of the carbonyls (Figure 1). The
three coordinating CO ligands are orthogonal to each other
and locate in three different chemical environments, in line
with the 13C NMR spectrum.
Synthesis of Imines. In an exploration of the optimum
conditions, the reaction of phenylmethanol with aniline was
studied as a model system for the acceptorless dehydrogenative
coupling to form imines (Table 1). The catalytic activities of
complex 2a and 2b were examined in refluxing toluene of
phenylmethanol (0.22 mmol), aniline (0.20 mmol), and
tBuOK (0.10 mmol) under a nitrogen atmosphere (see
Table 1, entries 1 and 2). In the presence of 3 mol % complex
Figure 1. Molecular structure of complex 2b.
catalyst 2a, 97% conversion was obtained for 4a with a higher
selectivity (98.1:1.9) for product imine 5a and product amine
5a′ (see Table 1, entry 1), while complex 2b yielded 90%
conversion for 4a and 77:23 selectivity for 5a:5a′ (see Table 1,
entry 2). The high catalytic activity and selectivity of complex
2a may be derived from the NH functionality.13 In the same
reactions of entry 1, heating the solution in a closed system
resulted in only 41% conversion for 4a (see Table 1, entry 3).
Next, the base effect on the reaction was evaluated. Use of
tBuONa obviously deteriorated the conversion (77%) (see
Table 1, entry 4). The case of utilizing KOH under similar
conditions gave 93% conversion for 4a and 29:71 selectivity for
5a:5a′ (see Table 1, entry 5), while the reaction proceeded less
efficiently with 80% conversion for 4a employing NaOH as a
base (see Table 1, entry 6). When Na2CO3 and K2CO3 were
used as the bases, the conversions for 4a were dropped from
14% to 3.2% (see Table 1, entries 7 and 8). Different solvents
were also screened for the reaction. In refluxing 1,4-dioxane,
both the conversion and the selectivity were decreased greatly
(see Table1, entry 9). In tetrahydrofuran (thf) or 2-Me-thf, the
substrates hardly reacted (see Table 1, entries 10 and 11).
Decreasing the catalyst loading to 2 mol % reduced the
conversion of 4a with deteriorated selectivity of 5a/5a′ (see
Table 1, entry 12). With 4 mol % catalyst loading, there’s no
evident improvement in conversion of 4a and selectivity of 5a/
B
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a
Table 1. Screening of Reaction Conditions
b
b
entry
1
catalyst loading (mol %)
base (0.5 equiv)
solvent (1.5 mL)
conv (%)
5a/5a′ (molar ratio) (%)
3
3
3
3
3
3
3
3
3
3
3
2
4
3
tBuOK
tBuOK
tBuOK
tBuONa
KOH
NaOH
Na2CO3
K2CO3
tBuOK
tBuOK
tBuOK
tBuOK
tBuOK
tBuOK
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
1,4-dioxane
thf
97
90
41
77
93
80
14
3.2
42
0.7
0.4
85
98
97
98.1:1.9
77:23
99:1
99.5:0.5
29:71
99.6:0.4
81:19
100
c
2
3
d
4
5
6
7
8
9
79.4:20.6
100
100
10
11
12
13
2-Me-thf
toluene
toluene
toluene
80:20
98:2
99.5:0.5(93)
e
f
14
a
b
Conditions: 3a (0.22 mmol), 4a (0.20 mmol), complex catalyst 2a (0.006 mmol), 110 °C, 0.1 MPa N2, 24 h. Determined by gas chromatography
c
d
e
f
analysis. Using complex catalyst 2b. Screening in sealed tube. Adding 5 mg of 4 Å MS. Isolated yield of 5a given in parentheses.
a
Table 2. Scope of Primary Alcohols 3
a
Conditions: 3 (0.55 mmol), 4a (0.50 mmol), complex 2a (0.015 mmol), tBuOK (0.25 mmol), 4 Å MS (12.5 mg), toluene (2 mL), 110 °C, 0.1
MPa N2, 24 h. Yields refer to the isolated products.
5a′ (see Table 1, entry 13). To our delight, the selectivity for
5a/5a′ was further improved if 5 mg of 4 Å MS was added, and
product imine 5a was isolated in 93% yield (see Table 1, entry
14). Different amounts of 4 Å MS, base loading, and the ratio
C
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a
Table 3. Scope of Amines 4
a
Conditions: 3a (0.55 mmol), 4 (0.50 mmol), catalyst 2a (0.015 mmol), tBuOK (0.25 mmol), 4 Å MS (12.5 mg), toluene (2 mL), 110 °C, 0.1
MPa N2, 24 h. Yields refer to the isolated products.
of 3a/4a were also screened for the reaction (see Supporting
Information for details).
(91%), exhibiting no steric effect. In a similar manner,
piperonyl alcohol and 4a were efficiently converted to 5u in
good isolated yield (81%). We also explored the reactivity of
alkyl alcohols, but the substrates were hardly reacted.
Under the optimal conditions, the scope of primary alcohols
3 was explored by means of their reactions with aniline (4a)
(Table 2). Methyl-substituted benzyl alcohol substrates
reacted with 4a to afford the target products 5b−5d in
73%−94% isolated yields and exhibited obvious steric impact
on the yields. The reactions of methoxy- and isopropyl-
substituted benzyl alcohols with 4a afforded products 5e−5i in
excellent yields (80−94%). It is noted that 2-MeO substituent
showed a negative effect on the reaction efficiency. F-, Cl-, and
Br- substituents on the aryl group of the benzyl alcohol
substrate did not demonstrate distinct electronic effect on the
product yields of 5g−5l (84%−95%). o-, m-, and p-Br-
substituted benzyl alcohols reacted efficiently with 4a to give
the corresponding products 5l−5n, showing a slight steric
effect on the yields (89%−93%). Importantly, the pharmaceuti-
cally active trifluoromethyl-substituted benzyl alcohol gave the
corresponding product 5o with excellent isolated yield (85%).
Similarly, heteroaromatic substrates, that is, thiophen-2-
ylmethanol, and furan-2-ylmethanol, also efficiently underwent
the reactions to generate 5p−5q (90%−96%). However, 2-
pyridinemethanol reacted with 4a less efficiently, giving 5r in
73% yield. Benzyl alcohol-containing imidazol moiety also
reacted with 4a to give 5s in good yield (82%). 1-
Naphthylmethanol efficiently reacted with 4a to afford 5t
Next, the generality of the protocol was investigated by using
diverse amines 4 as the coupling partners (Table 3). With
methyl substituent anilines as the substrates, their reactions
with benzyl alcohol afforded 5v (75%), 5w (90%), and 5x
(91%). An evident steric effect was revealed on the reactivity of
the o-Me-substituted aniline. Similarly, the o-, m-, and p-
methoxyls showed an obvious impact on the formation of 5y−
5aa (77%−95%) with the order o- < m- < p-methoxyl aniline.
The 2-ethyl group diminished the yield of 5ab (63%).
Halogen-substituted anilines also reacted well with 3a to
afford 5ac−5af in 90%−95% yields. Use of pyridin-2-amine as
the substrate slightly deteriorated the yield of 5ag (82%).
However, when pyridin-3-amine was used as the substrate, the
product yield dropped to 75% for 5ah. In the case of
naphthalen-2-amine, a decent yield was obtained to generate
5ai (83%). Benzylamine also efficiently reacted with benzyl
alcohol 3a, but its reaction gave the product 5aj in yield (77%)
lower than the corresponding reaction by using aniline 4a
(93%). Alkylamines, such as hexylamine and cyclohexylamine,
promoted the reactions to yield the target products 5ak and
5al in good yields (80%−88%).
D
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Scheme 3. Synthesis of Diimines
As an important structural unite, diimine compounds play a
vital role in constructing ligands in catalytic chemistry and
material applications.14,15 Further, to explore the synthetic
potential of the complex catalyst, attempts at synthesis of
diimine products were performed (Scheme 3). Benzene-1,3-
diamine or benzene-1,4-diamine similarly reacted well with
benzyl alcohol to afford diimine products 5am and 5an (80%
and 85%). For the disubstituted benzyl alcohol 1,3-benzene-
dimethanol, the product diimine was also acquired in 49%
yield.
The control experiments were conducted by reacting 3a
with two different steric effect anilines (aniline 4a, o-toluidine
4v), and reacting 4a with two different electronic effect benzyl
alcohols ((4-methoxyphenyl)methanol 3g, (4-(trifluorometh-
yl)-phenyl)methanol 3o) under the standard conditions
(Scheme 4). With aniline and o-methyl substituent aniline as
the substrates, their reactions with benzyl alcohol gave 87%
conversion and 73:27 selectivity for 5a/5v, and o-methyl
substituent exhibited a negative steric effect. When 4a reacted
with electron-donating and -withdrawing substituented benzyl
alcohols, 98% conversion and 71:29 selectivity for 5g/5o were
obtained. The 4-trifluoromethyl substituent demonstrated an
obvious negative electronic impact compared to the 4-methoxy
group.
To further probe into the catalyst activity, gram-scale
reaction was also performed under the optimized conditions.
The target product 5a was obtained in 65% yield (Scheme 5).
a
Scheme 5. Gram-Scale Reaction
a
Conditions: 3a (9.25 mmol), 4a (8.38 mmol), complex 2a (0.25
mmol), tBuOK (4.19 mmol), 4 Å MS (209.5 mg), toluene (30 mL),
110 °C, 0.1 MPa N2, 24 h. Yields refer to the isolated products.
a
Scheme 4. Control Experiments
This protocol may offer a potential application for large-scale
production. It is noteworthy that the reaction mechanism was
explored (Scheme 6) based on those reported work.9−11,13e,f
Initially, the acceptorless dehydrogenation of a primary alcohol
catalyzed by the manganese complex generates the correspond-
ing aldehyde. Considering that the present catalyst is Mn(I),
the reaction may involve (1) extrusion of 1 equiv of hydrogen
bromide with the base tBuOK, forming unsaturated 16-
electron mangenese complex, (2) 16-electron mangenese
complex interacts with BnOH to form [Mn]-OBn, (3) beta-
H elimination of [Mn]-OBn to form [Mn]-H and aldehyde,
and (4) the H2 releases from [Mn]-H and regenerates 16-
electron mangenese complex. Subsequent formation of the
imine product was achieved by condensation of the in situ
generated aldehyde and amine.
CONCLUSIONS
■
In summmary, we have developed an efficient and highly
selective phosphine-free NN-manganese(I) complex catalyst
system for the ADC of alcohols with amines to form imines.
Functional diimines also can be synthesized by this method-
ology. The present work provides an alternative method to
construct highly active nonprecious metal complex catalysts
based on bidentate phosphine-free ligands.
a
Conditions: 3a (0.55 mmol), 4a (0.25 mmol), 4v (0.25 mmol) for
eq (1); 3g (0.275 mmol), 3o (0.275 mmol), 4a (0.50 mmol) for eq
(2). complex 2a (0.015 mmol), tBuOK (0.25 mmol), 4 Å MS (12.5
mg), toluene (2 mL), 110 °C, 0.1 MPa N2, 24 h. Determined by gas
chromatography analysis.
E
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Scheme 6. Proposed Mechanism of the Reaction
mmol) and hydrazine hydrate (1.8 mL) in 5 mL of EtOH was stirred
at 80 °C for 2 h. After it cooled to ambient temperature, the reaction
was quenched with 20 mL of water and extracted with EtOAc (3 × 15
mL). The combined organic phase was concentrated under reduced
pressure. The resultant residue was subject to purification by column
chromatography on silica gel (eluent: CH2Cl2/CH3OH = 20:1, v/v)
to afford 1a. 127.7 mg, 88% yield, white solid, 1H NMR (CDCl3, 600
MHz): δ 11.81 (s, 1H), 8.68 (dt, J = 4.9, 1.4 Hz, 1H), 7.76 (d, J = 7.9
Hz, 1H), 7.69 (td, J = 7.6, 1.5 Hz, 1H), 7.65 (d, J = 2.1 Hz, 1H), 7.19
(ddd, J = 7.5, 4.9, 1.2 Hz, 1H), 6.80 (d, J = 2.2 Hz, 1H). 13C{1H}
NMR (CDCl3, 150 MHz): δ 149.8, 149.4, 145.5, 137.0, 136.6, 122.8,
120.4, 103.6.
Synthesis of Ligand 1b. Under a nitrogen atmosphere a mixture of
1a (145.2 mg, 1 mmol) and sodium hydride (120 mg, 5 mmol) in 20
mL of THF was stirred at 0 °C for 30 min. And iodomethane (124
μL, 2 mmol) was added to reaction system; after it was stirred for 5 h,
the reaction was quenched with 10 mL of methanol and mixed with
20 mL of water, then extracted with EtOAc (3 × 15 mL). The
combined organic phase was concentrated under reduced pressure.
The resultant residue was subjected to purification by column
chromatography on silica gel (eluent: CH2Cl2/CH3OH = 50:1, v/v)
to afford 1b. 143.3 mg, 90% yield, white solid, 1H NMR (CDCl3, 600
MHz): δ 8.62 (ddd, J = 4.8, 1.8, 1.0 Hz, 1H), 7.90 (dt, J = 7.8, 1.0 Hz,
1H), 7.70 (td, J = 7.7, 1.8 Hz, 1H), 7.41 (d, J = 2.2 Hz, 1H), 7.18
(ddd, J = 7.4, 4.8, 1.2 Hz, 1H), 6.86 (d, J = 2.3 Hz, 1H), 3.98 (s, 3H).
13C{1H} NMR (CDCl3, 150 MHz): δ 152.2, 151.7, 149.4, 136.6,
131.6, 122.3, 119.9, 104.4, 39.2.
EXPERIMENTAL SECTION
■
1
General Considerations. H and 13C{1H} NMR spectra were
recorded on a 600 MHz spectrometer, and all chemical shift values
refer to CDCl3 (δ(1H), 7.26 ppm; δ(13C), 77.16 ppm), deuterated
dimethyl sulfoxide (DMSO-d6) (δ(1H), 2.50 ppm; δ(13C), 39.52
ppm), CD3COCD3 (δ(1H), 2.05 ppm; δ(13C), 206.26 and 29.84
ppm), and CD3OD (δ(1H), 3.31 ppm; δ(13C), 49.00 ppm). X-ray
crystallographic analysis was achieved by Shiyanjia Lab (www.
shiyanjia.com). Analytical thin-layer chromatography (TLC) plates
were viewed by UV light (254 nm). Column chromatographic
purifications were performed on silica gel 160. All the chemical
reagents were purchased from commercial sources and used as
received unless otherwise indicated.
X-ray Crystallographic Studies. The X-ray diffraction studies
for complex 2b were performed on a SMART APEX diffractometer
with graphite-monochromated Mo radiation (λ = 0.710 73 Å). Cell
parameters were obtained by global refinement of the positions of all
collected reflections. Intensities were corrected for Lorentz and
polarization effects and empirical absorption. The structures were
solved by direct methods and refined by full-matrix least-squares on
F2. All non-hydrogen atoms were refined anisotropically. All hydrogen
atoms were placed in calculated positions. Structure solution and
refinement were performed by using the SHELXL-97 package. The X-
ray crystallographic files, in CIF format, are available from the
Cambridge Crystallographic Data Centre on quoting the deposition
number CCDC 1920267 for 2b. Additional crystallographic
information is available in the Supporting Information.
General Procedure for the Synthesis of Imines. Under a
nitrogen atmosphere a mixture of phenylmethanol (3a) (56.9 μL, 0.55
mmol), aniline (4a) (45.6 μL, 0.5 mmol), complex 2a (5.5 mg, 0.015
mmol), 4 Å MS (12.5 mg), and tBuOK (28.1 mg, 0.25 mmol) in 2.0
mL of toluene was stirred at 110 °C for 24 h. After it cooled to
ambient temperature, the reaction was quenched with 10 mL of water
and extracted with ethyl acetate (EtOAc) (3 × 10 mL). The
combined organic phase was concentrated under reduced pressure.
The resultant residue was subject to purification by column
chromatography on silica gel (eluent: n-hexane/ethyl ether = 20:1,
v/v) to afford 5a as a white solid (84.3 mg, 93%).
Synthesis of Complex 2a. Under a nitrogen atmosphere a mixture
of 1a (145.2 mg, 1 mmol) and manganese pentacarbonyl bromide
(274.9 mg, 1 mmol) in 30 mL of MeOH was stirred at 25 °C for 24 h.
All the volatiles were removed under reduced pressure, and the
resultant residue was subject to purification by recrystallization in
CHCl2/CH3OH/n-hexane (1/0.1/3, v/v/v) at 25 °C, affording the
1
complex as a yellow solid (309.43 mg, 85%). mp > 320 °C dec. H
NMR (CD3SOCD3, 600 MHz): δ 14.62 (s, 1H), 9.06 (d, J = 5.4 Hz,
1H), 8.22−8.19 (m, 2H), 8.13 (t, J = 7.6 Hz, 1H), 7.56 (t, J = 6.4 Hz,
1H), 7.29 (d, J = 2.4 Hz, 1H). 13C{1H} NMR (CD3SOCD3, 150
MHz): δ 222.5, 222.1, 221.6, 153.9, 151.8, 151.4, 139.7, 135.5, 125.3,
122.3, 104.9. IR (KBr pellets, cm−1): 2036 (ν CO), 1927 (ν CO).
Synthesis of Ligand 1a. Under a nitrogen atmosphere a mixture of
(E)-3-(dimethylamino)-1-(pyridin-2-yl)prop-2-en-1-one (176.2 mg, 1
F
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Anal. Calcd for C11H7BrMnN3O3: C, 36.29; H, 1.94; N, 11.54.
Found: C, 36.36; H, 1.98; N, 11.50%.
13C{1H} NMR (CD3COCD3, 150 MHz): δ 166.3, 164.6, 159.7,
152.8, 134.1, 131.8 (d, JC−F = 8.8 Hz), 130.0, 126.8, 121.7, 116.6 (d,
JC−F = 22.3 Hz).
(E)-1-(2-Chlorophenyl)-N-phenylmethanimine (5k). 102.5 mg,
95% yield, yellow liquid, 1H NMR (CD3COCD3, 600 MHz): δ
8.94 (s, 1H), 8.26−8.24 (m, 1H), 7.55−7.54 (m, 2H), 7.49−7.43 (m,
3H), 7.30−7.27 (m, 3H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
157.0, 152.7, 136.5, 134.1, 133.5, 130.9, 130.1, 129.3, 128.3, 127.3,
121.9.
Synthesis of Complex 2b. Under a nitrogen atmosphere a mixture
of 1b (159.2 mg, 1 mmol) and manganese pentacarbonyl bromide
(274.9 mg, 1 mmol) in 30 mL of MeOH was stirred at 25 °C for 24 h.
All the volatiles were removed under reduced pressure, and the
resultant residue was subject to purification by recrystallization in
CHCl2/CH3OH/n-hexane (1/0.1/3, v/v/v) at 25 °C, affording the
1
complex as a yellow solid (313.8 mg, 83%). mp > 320 °C dec. H
NMR (CD3SOCD3, 600 MHz): δ 9.08 (s, 1H), 8.18 (d, J = 42.8 Hz,
3H), 7.59 (s, 1H), 7.27 (s, 1H), 4.21 (s, 3H). 13C{1H} NMR
(CD3SOCD3, 150 MHz): δ 223.3, 223.0, 220.6, 153.7, 152.0, 151.6,
139.8, 138.4, 125.5, 122.2, 105.0, 40.4. IR (KBr pellets, cm−1): 2013
(ν CO), 1887 (ν CO). Anal. Calcd for C12H9BrMnN3O3: C, 38.12;
H, 2.40; N, 11.11. Found: C, 38.08; H, 2.37; N, 11.17%.
(E)-1-(2-Bromophenyl)-N-phenylmethanimine (5l). 115.8 mg,
89% yield, white solid, H NMR (CD3COCD3, 600 MHz): δ 8.87
1
(s, 1H), 8.23 (dd, J = 7.8, 1.8 Hz, 1H), 7.71 (dd, J = 8.0, 1.0 Hz, 1H),
7.52−7.42 (m, 4H), 7.29−7.28 (m, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 159.3, 152.6, 135.4, 134.1, 133.7,
130.1, 129.7, 128.8, 127.3, 126.4, 121.8.
(E)-1-(3-Bromophenyl)-N-phenylmethanimine (5m). 119.7 mg,
92% yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.58 (s,
1H), 8.16 (t, J = 1.8 Hz, 1H), 7.95−7.93 (m, 1H), 7.70−7.68 (m,
1H), 7.47 (t, J = 7.8 Hz, 1H), 7.43−7.41 (m, 2H), 7.29−7.25 (m,
3H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 159.4, 152.3, 139.7,
134.8, 131.8, 131.6, 130.0, 128.6, 127.1, 123.3, 121.8.
(E)-N,1-Diphenylmethanimine (5a). 84.3 mg, 93% yield, white
1
solid, H NMR (CD3OD, 600 MHz): δ 8.55 (s, 1H), 7.93−7.92 (m,
2H), 7.53−7.50 (m, 3H), 7.42−7.39 (m, 2H), 7.26−7.24 (m, 3H).
13C{1H} NMR (CD3OD, 150 MHz): δ 162.8, 153.0, 137.4, 132.7,
130.3, 129.9, 129.9, 127.3, 122.0.
(E)-N-Phenyl-1-(o-tolyl)methanimine (5b). 71.3 mg, 73% yield,
orange oil, 1H NMR (CD3COCD3, 600 MHz): δ 8.84 (s, 1H), 8.10−
8.07 (m, 1H), 7.43−7.25 (m, 8H), 2.64 (s, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 159.7, 153.6, 139.7, 135.2, 131.9, 131.8,
130.0, 128.7, 127.0, 126.6, 121.8, 19.5.
(E)-1-(4-Bromophenyl)-N-phenylmethanimine (5n). 121.0 mg,
1
93% yield, yellow solid, H NMR (CD3OD, 600 MHz) δ 8.51 (s,
1H), 7.83 (d, J = 8.5 Hz, 2H), 7.66 (d, J = 8.5 Hz, 2H), 7.41−7.38
(m, 2H), 7.25−7.23 (m, 3H). 13C{1H} NMR (CD3OD, 150 MHz): δ
161.2, 152.7, 136.6, 133.1, 131.4, 130.3, 127.5, 126.9, 122.0.
(E)-N-Phenyl-1-(m-tolyl)methanimine (5c). 87.9 mg, 90% yield,
1
orange oil, H NMR (CD3COCD3, 600 MHz): δ 8.54 (s, 1H), 7.79
(E)-N-Phenyl-1-(4-(trifluoromethyl)phenyl)methanimine (5o).
105.9 mg, 85% yield, yellow oil, 1H NMR (CD3COCD3, 600
MHz): δ 8.72 (s, 1H), 8.19 (d, J = 8.0 Hz, 2H), 7.87−7.86 (m, 2H),
7.45−7.43 (m, 2H), 7.32−7.27 (m, 3H). 13C{1H} NMR
(s, 1H), 7.75 (d, J = 7.5 Hz, 1H), 7.42−7.38 (m, 3H), 7.35 (d, J = 7.6
Hz, 1H), 7.25−7.22 (m, 3H), 2.41 (s, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 161.2, 153.1, 139.2, 137.5, 132.9,
130.0, 129.9, 129.5, 127.0, 126.6, 121.7, 21.3.
(CD3COCD3, 150 MHz): δ 159.7, 152.3, 140.9, 132.9 (q, JC−F
=
(E)-N-Phenyl-1-(p-tolyl)methanimine (5d). 91.8 mg, 94% yield,
yellow oil, 1H NMR (CD3OD, 600 MHz): δ 8.49 (s, 1H), 7.80 (d, J =
8.1 Hz, 2H), 7.40−7.38 (m, 2H), 7.32−7.31 (m, 2H), 7.24−7.21 (m,
3H), 2.41 (s, 3H). 13C{1H} NMR (CD3OD, 150 MHz): δ 162.9,
153.1, 143.6, 134.8, 130.6, 130.3, 130.0, 127.1, 122.0, 21.6.
(E)-1-(2-Methoxyphenyl)-N-phenylmethanimine (5e). 84.5 mg,
80% yield, white solid, 1H NMR (CD3OD, 600 MHz): δ 8.91 (s, 1H),
8.02 (dd, J = 7.7, 1.8 Hz, 1H), 7.50−7.47 (m, 1H), 7.40−7.37 (m,
2H), 7.24−7.21 (m, 1H), 7.20−7.19 (m, 2H), 7.10−7.08 (m, 1H),
7.05−7.02 (m, 1H), 3.91 (s, 3H). 13C{1H} NMR (CD3OD, 150
MHz): δ 161.2, 158.7, 153.6, 134.4, 130.3, 128.3, 127.1, 125.4, 122.0,
121.8, 112.6, 56.2.
(E)-1-(3-Methoxyphenyl)-N-phenylmethanimine (5f). 98.2 mg,
93% yield, white solid, 1H NMR (CD3OD, 600 MHz): δ 8.50 (s, 1H),
7.54−7.52 (m, 1H), 7.46−7.43 (m, 1H), 7.41−7.38 (m, 3H), 7.26−
7.23 (m, 3H), 7.09−7.07 (m, 1H), 3.86 (s, 3H). 13C{1H} NMR
(CD3OD, 150 MHz): δ 162.8, 161.6, 152.9, 138.7, 130.9, 130.3,
127.3, 123.2, 122.0, 119.2, 113.5, 55.8.
(E)-1-(4-Methoxyphenyl)-N-phenylmethanimine (5g). 89.8 mg,
85% yield, white solid, 1H NMR (CD3OD, 600 MHz): δ 8.45 (s, 1H),
7.86 (d, J = 8.8 Hz, 2H), 7.40−7.37 (m, 2H), 7.23−7.20 (m, 3H),
7.04 (d, J = 8.8 Hz, 2H), 3.86 (s, 3H). 13C{1H} NMR (CD3OD, 150
MHz): δ 164.2, 162.4, 153.2, 131.8, 130.3, 130.1, 126.9, 122.0, 115.3,
56.0.
(E)-1-(2,4-Dimethoxyphenyl)-N-phenylmethanimine (5h). 108.6
mg, 90% yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.79
(s, 1H), 8.06 (d, J = 8.3 Hz, 1H), 7.38 (t, J = 7.6 Hz, 2H), 7.20−7.16
(m, 3H), 6.66−6.64 (m, 2H), 3.94 (s, 3H), 3.89 (s, 3H). 13C{1H}
NMR (CD3COCD3, 150 MHz): δ 165.0, 162.1, 155.8, 154.2, 129.9,
129.3, 126.0, 121.7, 118.7, 107.1, 98.7, 56.2, 55.9.
32.2 Hz), 130.1, 130.1, 127.4, 126.5, 126.5, 121.9.
(E)-N-Phenyl-1-(thiophen-2-yl)methanimine (5p). 89.9 mg, 96%
1
yield, yellow oil, H NMR (CD3COCD3, 600 MHz): δ 8.74 (s, 1H),
7.71 (d, J = 5.0 Hz, 1H), 7.65 (dd, J = 3.6, 1.0 Hz, 1H), 7.41−7.38
(m, 2H), 7.26−7.20 (m, 4H). 13C{1H} NMR (CD3COCD3, 150
MHz): δ 154.1, 152.4, 144.1, 133.7, 131.3, 130.0, 128.7, 126.8, 121.8.
(E)-1-(Furan-2-yl)-N-phenylmethanimine (5q). 77.0 mg, 90%
yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.41 (s,
1H), 7.80 (s, 1H), 7.41−7.38 (m, 2H), 7.25−7.23 (m, 3H), 7.10 (d, J
= 2.7 Hz, 1H), 6.66 (dd, J = 3.4, 1.8 Hz, 1H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 153.7, 152.7, 148.9, 146.7, 130.0, 126.8,
121.7, 116.5, 113.1.
(E)-N-Phenyl-1-(pyridin-2-yl)methanimine (5r). 66.5 mg, 73%
1
yield, white liquid, H NMR (CD3COCD3, 600 MHz): δ 8.71 (m,
1H), 8.59 (s, 1H), 8.23−8.22 (m, 1H), 7.94 (td, J = 7.7, 1.7 Hz, 1H),
7.51−7.44 (m, 3H), 7.34−7.28 (m, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 161.7, 155.7, 152.1, 150.6, 137.6,
130.1, 127.5, 126.2, 121.9, 121.8.
(E)-1-(4-(1H-Imidazol-1-yl)phenyl)-N-phenylmethanimine (5s).
101.4 mg, 82% yield, white solid, 1H NMR (CD3COCD3, 600
MHz): δ 8.65 (s, 1H), 8.21 (s, 1H), 8.13−8.11 (m, 2H), 7.79 (d, J =
8.6 Hz, 2H), 7.70 (t, J = 1.5 Hz, 1H), 7.44−7.41 (m, 2H), 7.29−7.24
(m, 3H), 7.16 (s, 1H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
159.8, 152.7, 140.4, 136.3, 136.0, 131.4, 131.2, 130.0, 126.9, 121.8,
121.5, 118.5.
(E)-1-(Naphthalen-1-yl)-N-phenylmethanimine (5t). 105.2 mg,
1
91% yield, yellow solid, H NMR (CD3OD, 600 MHz): δ 9.16 (s,
1H), 9.00 (d, J = 8.5 Hz, 1H), 8.08−8.07 (dd, J = 7.2, 1.2 Hz, 1H),
8.01−7.93 (m, 2H), 7.62−7.53 (m, 3H), 7.44−7.41 (m, 2H), 7.31−
7.25 (m, 3H). 13C{1H} NMR (CD3OD, 150 MHz): δ 161.9, 153.6,
135.4, 133.1, 132.8, 132.7, 130.6, 130.3, 129.8, 128.5, 127.3, 127.2,
126.3, 125.2, 122.0.
(E)-1-(Benzo[d][1,3]dioxol-5-yl)-N-phenylmethanimine (5u). 91.2
mg, 81% yield, white solid, 1H NMR (CD3OD, 600 MHz): δ 8.40 (s,
1H), 7.48 (s, 1H), 7.39−7.34 (m, 3H), 7.23−7.19 (m, 3H), 6.92 (d, J
= 8.0 Hz, 1H), 6.04 (s, 2H). 13C{1H} NMR (CD3OD, 150 MHz): δ
162.1, 153.0, 152.3, 150.0, 132.2, 130.3, 127.4, 127.0, 122.0, 109.2,
107.4, 103.2.
(E)-1-(4-Isopropylphenyl)-N-phenylmethanimine (5i). 105.0 mg,
1
94% yield, yellow liquid, H NMR (CD3COCD3, 600 MHz): δ 8.54
(s, 1H), 7.89 (d, J = 8.2 Hz, 2H), 7.41−7.39 (m, 4H), 7.24−7.21 (m,
3H), 3.01−2.96 (m, 1H), 1.27 (d, J = 7.0 Hz, 6H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 160.9, 153.4, 153.2, 135.4, 129.9, 129.7,
127.6, 126.5, 121.7, 34.9, 24.1.
(E)-1-(4-Fluorophenyl)-N-phenylmethanimine (5j). 83.7 mg, 84%
yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.59 (s, 1H),
8.05−8.03 (m, 2H), 7.42−7.40 (m, 2H), 7.30−7.23 (m, 5H).
G
DOI: 10.1021/acs.organomet.9b00769
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(E)-1-Phenyl-N-(o-tolyl)methanimine (5v). 73.2 mg, 75% yield,
orange oil, 1H NMR (CD3COCD3, 600 MHz): δ 8.48 (s, 1H), 8.00−
7.98 (m, 2H), 7.53−7.52 (m, 3H), 7.24−7.21 (m, 2H), 7.12 (t, J =
7.4 Hz, 1H), 7.02−7.01 (m, 1H), 2.34 (s, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 160.2, 151.9, 137.7, 132.6, 132.1, 131.0,
129.6, 129.5, 127.6, 126.5, 118.4, 17.9.
1H), 8.50 (d, J = 2.6 Hz, 1H), 8.46 (dd, J = 4.7, 1.5 Hz, 1H), 8.01−
7.99 (m, 2H), 7.66−7.64 (m, 1H), 7.57−7.53 (m, 3H), 7.42−7.40
(m, 1H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 163.2, 148.6,
148.0, 143.8, 137.1, 132.6, 129.8, 129.7, 128.1, 124.6.
(E)-N-(Naphthalen-2-yl)-1-phenylmethanimine (5ai). 96.0 mg,
83% yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.75 (s,
1H), 8.04−8.02 (m, 2H), 7.96−7.91 (m, 3H), 7.71 (d, J = 1.8 Hz,
1H), 7.56−7.46 (m, 6H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
161.4, 150.6, 137.6, 135.2, 133.0, 132.2, 129.8, 129.7, 129.7, 128.7,
128.6, 127.3, 126.2, 122.0, 118.6.
(E)-1-Phenyl-N-(m-tolyl)methanimine (5w). 87.9 mg, 90% yield,
1
yellow liquid, H NMR (CD3COCD3, 600 MHz): δ 8.57 (s, 1H),
7.97−7.96 (m, 2H), 7.52−7.51 (m, 3H), 7.28 (t, J = 7.7 Hz, 1H),
7.08−7.04 (m, 3H), 2.36 (s, 3H). 13C{1H} NMR (CD3COCD3, 150
MHz): δ 160.7, 153.0, 139.6, 137.6, 132.1, 129.8, 129.6, 129.5, 127.4,
122.4, 118.8, 21.4.
(E)-N-Benzyl-1-phenylmethanimine (5aj). 75.2 mg, 77% yield,
orange oil, 1H NMR (CD3COCD3, 600 MHz): δ 8.50 (s, 1H), 7.84−
7.82 (m, 2H), 7.46−7.44 (m, 3H), 7.37−7.33 (m, 4H), 7.26−7.23
(m, 1H), 4.80 (s, 2H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
162.4, 140.9, 137.6, 131.4, 129.4, 129.2, 129.0, 128.8, 127.6, 65.4.
(E)-N-Hexyl-1-phenylmethanimine (5ak). 83.3 mg, 88% yield,
(E)-1-Phenyl-N-(p-tolyl)methanimine (5x). 88.8 mg, 91% yield,
1
yellow liquid, H NMR (CD3COCD3, 600 MHz): δ 8.59 (s, 1H),
7.96−7.94 (m, 2H), 7.51−7.50 (m, 3H), 7.22−7.17 (m, 4H), 2.34 (s,
3H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 160.1, 150.4, 137.7,
136.4, 132.0, 130.5, 129.6, 129.5, 121.7, 21.0.
1
white oil, H NMR (CD3COCD3, 600 MHz): δ 8.33 (s, 1H), 7.78−
7.76 (m, 2H), 7.43−7.42 (m, 3H), 3.58 (td, J = 6.9, 1.5 Hz, 2H),
1.68−1.63 (m, 2H), 1.39−1.29 (m, 6H), 0.90−0.87 (m, 3H).
13C{1H} NMR (CD3COCD3, 150 MHz): δ 161.0, 137.8, 131.2,
129.4, 128.7, 62.0, 32.4, 31.7, 27.8, 23.3, 14.3.
(E)-N-(2-Methoxyphenyl)-1-phenylmethanimine (5y). 81.3 mg,
1
77% yield, yellow oil, H NMR (CD3COCD3, 600 MHz): δ 8.53 (s,
1H), 7.96−7.95 (m, 2H), 7.52−7.50 (m, 3H), 7.19−7.16 (m, 1H),
7.06−7.02 (m, 2H), 6.96 (td, J = 7.5, 1.2 Hz, 1H), 3.83 (s, 3H).
13C{1H} NMR (CD3COCD3, 150 MHz): δ 161.8, 153.1, 142.9,
137.8, 132.0, 129.5, 129.5, 127.2, 121.8, 121.5, 113.0, 56.1.
(E)-N-Cyclohexyl-1-phenylmethanimine (5al). 74.9 mg, 80%
1
yield, yellow liquid, H NMR (CD3OD, 600 MHz): δ 8.38 (s, 1H),
7.74−7.73 (m, 2H), 7.44−7.43 (m, 3H), 3.28−3.23 (m, 1H), 1.87−
1.84 (m, 2H), 1.77−1.70 (m, 3H), 1.62−1.55 (m, 2H), 1.46−1.38
(m, 3H). 13C{1H} NMR (CD3OD, 150 MHz): δ 162.3, 137.3, 132.0,
129.7, 129.3, 71.3, 35.3, 26.7, 25.9.
(1E,1′E)-N,N′-(1,3-Phenylene)bis(1-phenylmethanimine) (5am).
113.7 mg, 80% yield, yellow solid, 1H NMR (CD3COCD3, 600
MHz): δ 8.67 (s, 2H), 8.01−7.99 (m, 4H), 7.54−7.53 (m, 6H),
7.46−7.43 (m, 1H), 7.16−7.15 (m, 3H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 161.5, 154.0, 137.5, 132.2, 130.6,
129.6, 129.6, 119.5, 113.9.
(E)-N-Benzylidine-3-methoxyaniline (5z). 94.0 mg, 89% yield,
yellow liquid, H NMR (CD3COCD3, 600 MHz): δ 8.58 (s, 1H),
7.97−7.96 (m, 2H), 7.52−7.49 (m, 3H), 7.32−7.29 (m, 1H), 6.85−
6.81 (m, 3H), 3.83 (s, 3H). 13C{1H} NMR (CD3COCD3, 150 MHz):
δ 161.4, 161.1, 154.4, 137.4, 132.1, 130.7, 129.6, 129.5, 113.9, 112.4,
107.2, 55.6.
1
(E)-N-(4-Methoxyphenyl)-1-phenylmethanimine (5aa). 100.4 mg,
95% yield, white solid, 1H NMR (CD3OD, 600 MHz): δ 8.53 (s, 1H),
7.89−7.87 (m, 2H), 7.48−7.46 (m, 3H), 7.26−7.24 (m, 2H), 6.95−
6.94 (m, 2H), 3.79 (s, 3H). 13C{1H} NMR (CD3OD, 150 MHz): δ
160.7, 160.1, 145.6, 137.6, 132.3, 129.8, 129.7, 123.3, 115.5, 55.9.
(E)-N-(2-Ethylphenyl)-1-phenylmethanimine (5ab). 65.9 mg, 63%
(1E,1′E)-N,N′-(1,4-Phenylene)bis(1-phenylmethanimine) (5an).
1
120.9 mg, 85% yield, pale yellow solid, H NMR (CD3COCD3, 600
1
MHz): 8.67 (s, 2H), 8.00−7.98 (m, 4H), 7.54−7.52 (m, 6H), 7.36 (s,
4H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 160.4, 150.9, 137.6,
132.1, 129.6, 129.6, 122.8.
(1E,1′E)-1,1′-(1,3-Phenylene)bis(N-phenylmethanimine) (5ao).
69.7 mg, 49% yield, yellow solid, 1H NMR (CD3COCD3, 600
MHz): δ 8.71 (s, 2H), 8.57 (s, 1H), 8.13 (dd, J = 7.6, 1.4 Hz, 2H),
7.68 (t, J = 7.6 Hz, 1H), 7.44 (t, J = 7.8 Hz, 4H), 7.33−7.31 (m, 4H),
7.28−7.25 (m, 2H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
160.5, 152.8, 138.1, 132.2, 130.1, 130.0, 129.5, 127.0, 121.8.
yield, yellow oil, H NMR (CD3COCD3, 600 MHz): δ 8.51 (s, 1H),
8.00−7.98 (m, 2H), 7.53−7.52 (m, 3H), 7.26−7.15 (m, 3H), 7.03
(dd, J = 7.7, 1.3 Hz, 1H), 2.79 (q, J = 7.5 Hz, 2H), 1.17 (t, J = 7.6 Hz,
3H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 160.3, 151.3, 138.8,
137.7, 132.1, 129.6, 129.5, 129.5, 127.7, 126.8, 118.5, 25.5, 15.5.
(E)-N-(4-Fluorophenyl)-1-phenylmethanimine (5ac). 94.6 mg,
1
95% yield, white solid, H NMR (CD3COCD3, 600 MHz): δ 8.60
(s, 1H), 7.97−7.96 (m, 2H), 7.53−7.50 (m, 3H), 7.33−7.31 (m, 2H),
7.19−7.16 (m, 2H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
162.8, 161.1 (d, JC−F = 1.8 Hz), 149.2, 137.4, 132.2, 129.6 (d, JC−F
3.3 Hz), 123.5 (d, JC−F = 8.3 Hz), 116.6, 116.5.
=
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.organomet.9b00769.
■
(E)-N-(4-Chlorophenyl)-1-phenylmethanimine (5ad). 98.1 mg,
S
1
91% yield, white solid, H NMR (CD3COCD3, 600 MHz): δ 8.60
(s, 1H), 7.97 (d, J = 6.2 Hz, 2H), 7.54−7.50 (m, 3H), 7.43 (d, J = 8.7
Hz, 2H), 7.28 (d, J = 8.7 Hz, 2H). 13C{1H} NMR (CD3COCD3, 150
MHz): δ 161.8, 151.7, 137.2, 132.4, 131.7, 130.0, 129.7, 129.6, 123.4.
N-(3-Chlorophenyl)-1-phenylmethanimine (5ae). 97.1 mg, 90%
NMR spectra of the new compounds and the X-ray
crystallographic data for 2b (PDF)
Crystallographic X-ray data for 2b (XYZ)
1
yield, yellow oil, H NMR (CD3COCD3, 600 MHz): δ 8.60 (s, 1H),
7.99−7.97 (m, 2H), 7.55−7.51 (m, 3H), 7.42 (t, J = 7.9 Hz, 1H),
7.29−7.26 (m, 2H), 7.22−7.20 (m, 1H). 13C{1H} NMR
(CD3COCD3, 150 MHz): δ 162.6, 154.5, 137.1, 135.1, 132.5,
131.4, 129.8, 129.6, 126.4, 121.6, 120.6.
(E)-N-(4-Bromophenyl)-1-phenylmethanimine (5af). 122.3 mg,
94% yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 8.60 (s,
1H), 7.97 (d, J = 6.6 Hz, 2H), 7.58−7.51 (m, 5H), 7.22 (d, J = 8.5
Hz, 2H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ 161.4, 151.7,
136.8, 132.5, 132.0, 129.3, 129.2, 123.4, 119.1.
Accession Codes
CCDC 1920267 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(E)-1-Phenyl-N-(pyridin-2-yl)methanimine (5ag). 74.7 mg, 82%
yield, white solid, 1H NMR (CD3COCD3, 600 MHz): δ 9.23 (s, 1H),
8.50−8.49 (m, 1H), 8.06−8.05 (m, 2H), 7.86 (td, J = 7.6, 1.9 Hz,
1H), 7.57−7.53 (m, 3H), 7.34 (dt, J = 7.9, 1.0 Hz, 1H), 7.27 (ddd, J =
7.4, 4.8, 1.1 Hz, 1H). 13C{1H} NMR (CD3COCD3, 150 MHz): δ
163.2, 161.8, 149.8, 139.1, 137.1, 132.8, 130.2, 129.7, 122.9, 120.9.
(E)-1-Phenyl-N-(pyridin-3-yl)methanimine (5ah). 68.3 mg, 75%
AUTHOR INFORMATION
Corresponding Author
*E-mail: chaihuining@qut.edu.cn.
ORCID
Huining Chai: 0000-0002-7267-2952
Kun Yu: 0000-0001-7342-8938
■
1
yield, white liquid, H NMR (CD3COCD3, 600 MHz): δ 8.66 (s,
H
DOI: 10.1021/acs.organomet.9b00769
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
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Bo Liu: 0000-0003-4526-714X
Weiqiang Tan: 0000-0003-2737-2018
Guangyao Zhang: 0000-0002-7159-5166
Author Contributions
∥These authors contributed equally to this work.
Notes
The authors declare the following competing financial
interest(s): The authors declare no competing financial
interest.
ACKNOWLEDGMENTS
■
We are grateful to the National Natural Science Foundation of
China (21801158) and the Open Project Fund of Qingdao
University of Technology (QUTSEME201934) for support of
this research. We thank Prof. Z.-K. Yu (DICP) for helpful
discussion.
́
́
M. A.; Lezaun, V.; Martínez, A.; Olivan, M.; Onate, E. Osmium
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Hydride Acetylacetonate Complexes and Their Application in
Acceptorless Dehydrogenative Coupling of Alcohols and Amines
and for the Dehydrogenation of Cyclic Amines. Organometallics 2017,
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(7) Zhang, G.; Hanson, S. K. Cobalt-Catalyzed Acceptorless Alcohol
Dehydrogenation: Synthesis of Imines from Alcohols and Amines.
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