tBuLi-Promoted Intermolecular Regioselective Nucleophilic Addition of Arenes to Diazo Compounds as N-Terminal Electrophiles: Efficient Synthesis of Hydrazine Derivatives

Article abstract of DOI:10.1002/ejoc.201700864

The tBuLi-promoted intermolecular direct nucleophilic addition of arenes to diazo compounds as the N-terminal electrophiles has been developed. This reaction proceeds in a completely regioselective manner and is an efficient method for the preparation of hydrazine derivatives in high to excellent yields. This transformation not only provides an efficient approach for aromatic C–N bond formation under transition-metal-free and oxidant-free conditions but also represents a strategy for the 3-amination of pyridines and the dearomatization of indoles.

Full text of DOI:10.1002/ejoc.201700864

DOI: 10.1002/ejoc.201700864
Full Paper
Diazo Compounds
tBuLi-Promoted Intermolecular Regioselective Nucleophilic
Addition of Arenes to Diazo Compounds as N-Terminal
Electrophiles: Efficient Synthesis of Hydrazine Derivatives
Lu Zhang,[a] Xiang-He Meng,[a] Pei Liu,[a] Jie Chen,[b] and Yu-Long Zhao*[a]
Abstract: The tBuLi-promoted intermolecular direct nucleo- yields. This transformation not only provides an efficient ap-
philic addition of arenes to diazo compounds as the N-terminal proach for aromatic C–N bond formation under transition-
electrophiles has been developed. This reaction proceeds in a metal-free and oxidant-free conditions but also represents a
completely regioselective manner and is an efficient method strategy for the 3-amination of pyridines and the dearomatiza-
for the preparation of hydrazine derivatives in high to excellent tion of indoles.
Introduction
nitrogen atom of these compounds has rarely been studied.[11]
Recently, an elegant nBuLi-promoted method for the nucleo-
philic addition of arenes to aryldiazonium salts as N-terminal
electrophiles was carried out by Feringa and Szymanski
(Scheme 1a).[12] However, to date, the direct nucleophilic addi-
tion of aromatic precursors to diazo compounds has not been
realized. Herein, we report a regioselective tBuLi-promoted
method for the intermolecular direct nucleophilic addition of
arenes to diazo compounds as the N-terminal electrophiles. This
approach is successful with a broad range of arenes, particularly
a variety of heteroarenes (Scheme 1b). Moreover, this reaction
not only provides an efficient strategy for the formation of
aromatic C–N bonds but also represents a method for the 3-
amination of pyridines and the dearomatization of indoles
(Scheme 1 b).
Arylamines are privileged structural motifs that are found in a
wide variety of biologically active compounds, pharmaceutical
targets, and functional materials.[1] The development of effi-
cient and step-economical methods for the construction of
aromatic C–N bonds has attracted organic chemists for several
decades.[2–6] Despite remarkable advances in the formation of
aromatic C–N bonds using the Ullmann and Buchwald–Hartwig
amination reactions,[3] the need of aryl (pseudo)halides for
these approaches has led synthetic chemists towards methods
for direct aminations of arene C–H bonds. Generally, these di-
rect amination approaches rely on transition-metal-catalyzed
strategies.[4] In the case of transition-metal-free systems, a stoi-
chiometric amount of chemical oxidants, such as hypervalent
iodine reagents and peroxides, are necessary.[5] The C–H amin-
ation of arenes by using electrophilic aminating agents is an
effective approach to C–N bond formation. These reactions,
however, suffer from a limited substrate scope, poor regio-
selectivity, the use of expensive transition-metal catalysts, and
the generation of stoichiometric amounts of byproducts.[6]
Thus, the development of aromatic C–N bond-forming reactions
that provide high regioselectivity in the absence of transition
metals and chemical oxidants is highly desired.
Diazo compounds are important building blocks in synthetic
chemistry.[7] These compounds have been extensively studied
as metal carbene precursors,[8] 1,3-dipoles,[9] and C-nucleo-
philes.[10] However, the electrophilic capability of the terminal
[a] Jilin Province Key Laboratory of Organic Functional Molecular Design and
Synthesis, Faculty of Chemistry, Northeast Normal University,
Changchun 130024, China
E-mail: zhaoyl351@nenu.edu.cn
[b] Research Institute of Exploration and Development, PetroChina Daqing Oil-
field Company Limited,
Daqing 163712, China
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejoc.201700864.
Scheme 1. Nucleophilic addition of arenes to diazo compounds (THF = tetra-
hydrofuran).
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Results and Discussion
of steric hindrance in the reaction. In addition to aryl methyl
ethers as substrates, the nucleophilic addition of aromatic nitro-
gen heterocycles such as 1-methyl-1H-imidazole (1j) and 1-
methyl-1H-pyrrole (1k) proceeded smoothly with excellent se-
lectivity to produce the desired products 3aj, 3bj, and 3bk in
high yields. Similarly, 1-methyl-1H-benzo[d]imidazole (1l) was
also used as effective carbon nucleophile and afforded the 2-
amine products in 75 % yield as tautomers 3bl/3bl′ in a ratio
of approximately 4:1 (Table 2).
As part of our research on C–C and C–N bond formation,[13]
we recently developed a reaction between active methylene
compounds and α-diazocarbonyl derivatives as N-terminal elec-
trophiles that takes place under mild conditions.[14] On the basis
of these experimental results,[12–14] we envisioned that an inter-
molecular direct nucleophilic addition of arenes to diazo com-
pounds might be realized by using diazo species as N-terminal
electrophiles. To test this hypothesis, the reaction of anisole
(1a) with diphenyldiazomethane (2a) was first examined under
various basic reaction conditions. After many attempts, we
found that the nucleophilic addition of 1a (1.0 mmol) to 2a
(0.5 mmol) smoothly afforded the desired 1-(diphenylmethyl-
ene)-2-(2-methoxyphenyl)hydrazine (3aa) in 92 % yield when
the reaction was performed in the presence of tBuLi (2.0 equiv.)
in anhydrous THF (4.0 mL) at room temperature for 30 min
(Table 1, Entry 3). The transformation exclusively took place or-
tho to the methoxy group, and amination at the para position
was not observed, which was expected as the ortho lithiation
of anisole is preferred.[15] Decreasing the amount of tBuLi led
to comparatively lower yields (Table 1, Entries 1 and 2). Other
bases such as nBuLi, lithium diisopropylamide (LDA), tBuOK,
and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were either less
effective (Table 1, Entry 4) or ineffective (Table 1, Entries 5–7).
Table 2. tBuLi-promoted nucleophilic addition of arenes 1 to diaryldiazometh-
anes 2a or 2b.[a,b]
Table 1. Optimization of the reaction conditions.[a]
Entry
Base [equiv.]
Solvent
Time [min]
Yield [%][b]
1
2
3
4
5
6
7
tBuLi (1.0)
tBuLi (1.5)
tBuLi (2.0)
nBuLi (2.0)
LDA (2.0)
THF
THF
THF
THF
THF
THF
THF
30
30
30
40
60
60
60
47
81
92
65
–
tBuOK (2.0)
DBU (2.0)
–
–
[a] Reagents and conditions: 1a (1.0 mmol), 2a (0.5 mmol), base (0.5–
1.0 mmol), and solvent (4.0 mL) at room temperature under nitrogen. [b] Iso-
lated yields are provided.
[a] Reagents and conditions: 1 (1.0 mmol), 2 (0.5 mmol), tBuLi (1.0 mmol)
and THF (4.0 mL) at room temperature for 30–60 min. [b] Isolated yields are
provided. [c] After the mixture of 1 and tBuLi in THF was stirred at –20 °C for
28 min, 2 was added at –70 °C. [d] tBuLi (4.0 equiv.) and 1k (4.0 equiv.) were
used.
Under the optimal conditions (Table 1, Entry 3), the scope
and generality of the tBuLi-promoted direct nucleophilic addi-
tion of arenes 1 to diaryldiazomethanes 2 was examined, and
the results are summarized in Table 2. The reaction showed a
broad tolerance for various arenes. All anisole derivatives 1a–
Interestingly, when the reaction between pyridine 1m and
1f, which contain electron-donating Me, SMe, or OMe, electron- 2b was carried out at –20 °C in the presence of tBuLi (2.5 equiv.)
withdrawing Cl, or ethynyl functional substituents, smoothly under otherwise identical conditions, 2-tert-butyl-5-(2-methyl-
underwent the reaction with diphenyldiazomethane (2a) in a enehydrazinyl)pyridine 3bm was obtained in 71 % yield
completely regioselective manner to give the desired 1-(di- through a sequential alkylation/amination process (Table 3).
phenylmethylene)-2-arylhydrazines 3aa–3af in high to excel- Similarly, the double nucleophilic addition reaction of pyridine
lent yields within 30–40 min. It is noteworthy that 1,3- derivatives 1n–1q and 2b also took place efficiently, and the
dimethoxybenzene (1g), 1,3,5-trimethoxybenzene (1h), and 2- desired products 3bn–3bq, respectively, were formed in good
methoxynaphthalene (1i) also provided the desired products to high yields. These results present a simple and efficient strat-
3ag–3ai in excellent yields, which indicates a good tolerance egy for the amination of pyridines.[16]
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Table 3. tBuLi-promoted nucleophilic addition of pyridines 1m–1q to 2b.[a,b]
(Table 4).[17] In addition, when unsymmetrical diaryldiazometh-
ane 2f was used as the electrophilic reagent, a mixture of the
desired (E)- and (Z)-1-(2-methoxyphenyl)-2-[(4-methoxyphenyl)-
(phenyl)methylene]hydrazines (3fa/3fa′) were obtained in 90 %
yield. Notably, in the case of α-diazoesters 2g–2i, the nucleo-
philic addition also worked well and yielded the desired (Z)
products 3ga–3ia in a regioselective manner in good to high
yields. Interestingly, when the reaction of 1a (4.0 equiv.) with
2g was performed in the presence of tBuLi (4.0 equiv.) under
otherwise identical conditions, the (Z) product 3ga′ was pro-
duced in 90 % yield through the concomitant nucleophilic addi-
tion of the excess amount (2.0 equiv.) of the aryllithium at the
carbonyl carbon of the ethoxycarbonyl group.[18] No desired
product, however, was produced when ethyl diazoacetate 2j
was used as the N-terminal electrophile, even under low tem-
perature conditions.
Because of the significance of indole derivatives[19] and to
further explore the generality of this reaction for aromatic
heterocyclic compounds, the nucleophilic addition reaction of
N-substituted indoles 1r–1w with diaryldiazomethanes 2 was
investigated, and the results are summarized in Table 5. Under
identical conditions, the nucleophilic addition of N-substituted
indoles 1r–1w, which contain either electron-donating or elec-
tron-withdrawing groups on the phenyl ring, exclusively oc-
curred at the 2-position to give the corresponding (E)-2-[(diaryl-
methylene)hydrazono]indolines 4a–4h in high to excellent
yields by a sequential amination/dearomatization process
(Table 5).[20] It should be noted that dearomatization reactions
are important transformations for aromatic compounds, as they
can directly lead to a variety of ring systems from simple start-
ing materials.[21] In this field, because of the potent biological
activities and pharmaceutical applications of indoline alkaloids,
[a] Reagents and conditions: 1m–1q (1.0 mmol), 2b (0.5 mmol), tBuLi
(1.25 mmol), and THF (4.0 mL), at –20 °C for 35–40 min. [b] Isolated yields
are provided.
Next, we investigated the scope of the reaction with regard
to the diazo compound (Table 4). All diaryldiazomethanes 2b–
2e, which contain electron-rich or electron-deficient aromatic
R1 and R2 groups, underwent the reaction with 1a to give
the corresponding products 3ba–3ea in excellent yields
Table 4. tBuLi-promoted nucleophilic addition of anisole 1a to diazo com-
pounds 2.[a,b]
Table 5. tBuLi-promoted nucleophilic addition of N-substituted indoles 1 to
diazo compounds 2.[a,b]
[a] Reagents and conditions: 1a (1.0 mmol), 2 (0.5 mmol), tBuLi (1.0 mmol),
and THF (4.0 mL) at room temperature for 30–60 min. [b] Isolated yields are
provided. [c] After the mixture of 1a and tBuLi in THF was stirred at –20 °C
for 28 min, 2 was added at –70 °C. [d] tBuLi (4.0 equiv.) and 1a (4.0 equiv.)
were used.
[a] Reagents and conditions: 1r–1w (1.0 mmol),
(1.0 mmol), and THF (4.0 mL) at room temperature for 30–40 min. [b] Isolated
yields are provided.
2 (0.5 mmol), tBuLi
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the dearomatization of indoles has attracted considerable at- ally broad substrate scope. This transformation not only pro-
tention, and some elegant dearomative strategies have been vides an efficient method for aromatic C–N bond formation un-
developed.[21,22] Thus, the present work not only provides an der transition-metal-free and oxidant-free conditions but also
efficient method of aromatic C–N bond formation but also rep- represents a strategy for the 3-amination of pyridines and the
resents a strategy for the dearomatization of indoles.
dearomatization of indoles. Further work on applications and
extending the scope of this protocol are currently under investi-
gation in our laboratory.
Furthermore, we found that this nucleophilic addition reac-
tion was easy to scale up. A gram-scale reaction of 1.3 g of 1a
and 1.6 g of 2b was carried out under the optimal conditions
and furnished 2.0 g of the desired product 3ba in an isolated
yield of 90 % (Scheme 2). Arylhydrazines are a highly valuable
class of building blocks for the synthesis of important nitrogen-
containing heterocycles.[23] However, most synthetic methods
suffer from a limited substrate scope or the need of multistep
procedures and expensive transition-metal catalysts.[12,24] This
reaction provides a direct and efficient method for the con-
struction of various arylhydrazines in high to excellent yields.[25]
We also found that the cyclization of 3ba (0.2 mmol) smoothly
proceeded to give 1H-indazole 5 in 60 % yield in the presence
of iodobenzene (10 mol-%) and potassium peroxomonosulfate
(Oxone, 1.5 equiv.) in trifluoroacetic acid (TFA, 2.0 mL) at –10 °C
for 35 min (Scheme 2).
Experimental Section
General Methods: Unless noted otherwise, all the reactions were
performed in a reaction vessel under nitrogen. Room temperature
was approximately 25 °C. All solvents were freshly distilled and de-
gassed according to the literature.[27] Flash chromatography was
performed on silica gel (300–400 mesh). All reactions were moni-
tored by TLC analysis, which was performed on aluminum sheets
1
that were precoated with silica gel 60 (F254). Unless noted, the H
NMR spectroscopic data were recorded at 500 or 600 MHz, and
CDCl3 was used as the NMR solvent. The 13C NMR spectroscopic
data were recorded at 125 or150 MHz, and CDCl3 was used as the
solvent along with TMS as the internal standard. All coupling con-
stants were reported in Hertz (Hz). High resolution mass spectral
data were obtained with a BrukermicroTOF II focus spectrometer
(ESI).
General Procedure for the Preparation of 3 – Synthesis of 1-
(Diphenylmethylene)-2-(2-methoxyphenyl)hydrazine (3aa): To a
stirred solution of 1a (1.0 mmol, 0.11 mL) in dry THF (2.0 mL) in an
oven-dried Schlenk flask under N2 at room temperature was slowly
Scheme 2. Gram scale and synthetic application.
added tBuLi (1.3
M in hexane, 0.77 mL, 1.0 mmol), and the reaction
mixture was stirred at room temperature for 28 min. The mixture
of 2a (0.5 mmol, 97.1 mg) in dry THF (2.0 mL) was then added
under N2 at room temperature. The resulting mixture was stirred at
room temperature for 2 min, and then H2O (10 mL) was added. The
solution was extracted with CH2Cl2 (3 × 10 mL), and the combined
organic extracts were dried with anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The crude product was puri-
fied by flash chromatography on a silica gel column (basic, 300–
400 mesh; petroleum ether/diethyl ether, 10:1 v/v) to give 3aa
(138.9 mg, 92 %) as a yellow solid; m.p. 101–103 °C. 1H NMR
(500 MHz, CDCl3): δ = 8.00 (s, 1 H), 7.67 (dd, J = 7.9, 1.4 Hz, 1 H),
7.62–7.59 (m, 2 H), 7.55 (t, J = 7.4 Hz, 2 H), 7.47 (ddd, J = 6.5, 3.9,
1.1 Hz, 1 H), 7.36–7.32 (m, 2 H), 7.32–7.27 (m, 2 H), 7.26 (ddd, J =
7.3, 3.4, 1.2 Hz, 1 H), 6.97 (td, J = 7.9, 1.1 Hz, 1 H), 6.78 (td, J = 7.7,
1.5 Hz, 1 H), 6.73 (dd, J = 8.0, 1.2 Hz, 1 H), 3.64 (s, 3 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 145.30, 144.72, 138.49, 134.12, 132.95,
129.47, 129.00, 128.95, 128.08, 127.83, 126.45, 121.47, 119.09,
112.25, 109.96, 55.42 ppm. HRMS (ESI-TOF): calcd. for C20H18N2NaO+
[M + Na]+ 325.1311; found 325.1304.
On the basis of our experimental results and a related re-
port,[26] a possible reaction mechanism for the formation of
3bm–3bq has been proposed (Scheme 3). Initially, the tBuLi
undergoes an intermolecular nucleophilic addition to pyridines
1m–1q to give intermediate A/A′. The carbanion of intermedi-
ate A′ then attacks the terminal nitrogen atom of diazo com-
pound 2b to generate intermediate B. Finally, intermediate B is
readily oxidized by O2 in the process of treating the reaction
mixture, and a subsequent protonation leads to products
3bm–3bq (Scheme 3).
Conclusions
In summary, we have developed a tBuLi-promoted intermolec-
ular direct nucleophilic addition of arenes to diazo compounds
as the N-terminal electrophiles. This reaction proceeds in a com-
1-(Diphenylmethylene)-2-(2-methoxy-5-methylphenyl)hydraz-
1
pletely regioselective manner and demonstrates an exception- ine (3ab): Yellow solid (147.1 mg, 93 %); m.p. 139–140 °C. H NMR
Scheme 3. Proposed mechanisms for the formation of 3bm–3bq.
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(500 MHz, CDCl3): δ = 7.96 (s, 1 H), 7.65–7.58 (m, 2 H), 7.55 (t, J =
7.4 Hz, 2 H), 7.48 (dd, J = 8.7, 4.7 Hz, 2 H), 7.37–7.28 (m, 4 H), 7.26
(500 MHz, CDCl3): δ = 7.53 (dd, J = 15.4, 7.8 Hz, 4 H), 7.46 (d, J =
7.5 Hz, 1 H), 7.42 (d, J = 7.1 Hz, 2 H), 7.27–7.20 (m, 3 H), 7.12 (s, 1
(dd, J = 8.3, 6.1 Hz, 1 H), 6.63 (d, J = 8.1 Hz, 1 H), 6.57 (dd, J = 8.1, H), 6.16 (s, 2 H), 3.82 (s, 6 H), 3.76 (s, 3 H) ppm. 13C NMR (125 MHz,
1.2 Hz, 1 H), 3.62 (s, 3 H), 2.34 (s, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 157.14, 153.90, 147.57, 138.74, 133.52, 129.27, 129.11,
CDCl3): δ = 144.69, 143.41, 138.59, 133.80, 133.05, 131.01, 129.52, 128.79, 127.93, 127.72, 126.57, 117.30, 91.70, 56.30, 55.47 ppm.
129.03, 128.14, 127.85, 126.51, 119.37, 113.01, 110.08, 55.67, HRMS (ESI-TOF): calcd. for C22H22N2NaO3 [M + Na]+ 385.1523;
+
21.15 ppm. HRMS (ESI-TOF): calcd. for C21H20N2NaO+ [M + Na]+
339.146; found 339.1451.
found 385.1528.
1-(Diphenylmethylene)-2-(2-methoxynaphthalen-1-yl)hydraz-
ine (3ai): Yellow solid (158.6 mg, 90 %); m.p. 171–172 °C. H NMR
1
1-(Diphenylmethylene)-2-[2-methoxy-5-(methylthio)phenyl]-
hydrazine (3ac): White solid (130.7 mg, 75 %); m.p. 163–165 °C. 1H
NMR (500 MHz, CDCl3): δ = 7.96 (s, 1 H), 7.66 (s, 1 H), 7.60 (d, J =
7.3 Hz, 2 H), 7.55 (t, J = 7.3 Hz, 2 H), 7.49 (t, J = 7.1 Hz, 1 H), 7.38–
7.24 (m, 5 H), 6.74 (d, J = 6.9 Hz, 1 H), 6.66 (d, J = 8.2 Hz, 1 H), 3.62
(s, 3 H), 2.50 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 145.36,
143.95, 138.26, 134.43, 132.81, 129.97, 129.48, 129.08, 128.87,
128.10, 128.01, 126.53, 118.95, 112.40, 110.54, 55.63, 17.76 ppm.
HRMS (ESI-TOF): calcd. for C21H21N2OS+ [M + H]+ 349.1369; found
349.1362.
(500 MHz, CDCl3): δ = 8.21 (s, 1 H), 7.90 (s, 1 H), 7.76 (d, J = 8.1 Hz,
1 H), 7.68 (d, J = 7.2 Hz, 2 H), 7.64–7.55 (m, 3 H), 7.52 (t, J = 7.4 Hz,
1 H), 7.37 (dd, J = 17.6, 7.4 Hz, 4 H), 7.33–7.27 (m, 2 H), 7.27–7.20
(m, 1 H), 6.99 (s, 1 H), 3.77 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 146.73, 146.02, 138.41, 134.14, 132.93, 130.12, 129.54, 129.18,
129.01, 128.51, 128.21, 128.17, 126.74, 126.31, 124.13, 123.04,
106.90, 105.04, 55.52 ppm. HRMS (ESI-TOF): calcd. for C24H20N2NaO+
[M + Na]+ 375.1468; found 375.1461.
2-[2-(Diphenylmethylene)hydrazinyl]-1-methyl-1H-imidazole
(3aj): Yellow liquid (100.9 mg, 73 %). 1H NMR (500 MHz, CDCl3): δ =
7.65 (s, 1 H), 7.57–7.52 (m, 2 H), 7.52–7.46 (m, 3 H), 7.35–7.32 (m, 2
H), 7.30 (dd, J = 6.4, 2.8 Hz, 3 H), 6.67 (d, J = 1.3 Hz, 1 H), 6.63 (d,
J = 1.2 Hz, 1 H), 3.82 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
147.69, 146.06, 137.67, 132.00, 129.61, 129.40, 128.79, 128.48,
128.15, 126.60, 124.23, 118.79, 33.81 ppm. HRMS (ESI-TOF): calcd.
1-(5-Chloro-2-methoxyphenyl)-2-(diphenylmethylene)-
hydrazine (3ad): Yellow solid (134.7 mg, 80 %); m.p. 170–172 °C.
1H NMR (500 MHz, CDCl3): δ = 7.94 (s, 1 H), 7.62 (dd, J = 4.0, 2.1 Hz,
2 H), 7.60 (d, J = 0.9 Hz, 1 H), 7.57 (dd, J = 11.3, 4.3 Hz, 2 H), 7.53–
7.48 (m, 1 H), 7.35–7.28 (m, 5 H), 6.71 (dd, J = 8.5, 2.5 Hz, 1 H), 6.62
(d, J = 8.5 Hz, 1 H), 3.64 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 146.05, 143.97, 138.16, 135.09, 132.75, 129.58, 129.24, 128.90,
128.27, 128.21, 126.84, 126.70, 118.27, 112.25, 110.80, 55.75 ppm.
HRMS (ESI-TOF): calcd. for C20H17ClN2NaO+ [M + Na]+ 359.0922;
found 359.0917.
for C17H17N4 [M + H]+ 277.1448; found 277.1452.
+
2-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-1-methyl-1H-
imidazole (3bj): Yellow solid (129.5 mg, 75 %); m.p. 186–188 °C. 1H
NMR (600 MHz, CDCl3): δ = 7.65 (s, 1 H), 7.52 (d, J = 7.4 Hz, 2 H),
7.39 (d, J = 8.6 Hz, 2 H), 7.31–7.22 (m, 4 H), 6.65 (d, J = 12.1 Hz, 2
H), 3.78 (s, 3 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 145.66, 145.47,
1-(Diphenylmethylene)-2-(5-ethynyl-2-methoxyphenyl)hydraz-
1
ine (3ae): Yellow solid (140.4 mg, 86 %); m.p. 155–156 °C. H NMR 135.98, 134.66, 130.43, 130.15, 128.51, 127.83, 124.63, 119.06,
33.73 ppm. HRMS (ESI-TOF): calcd. for C17H15Cl2N4 [M + H]+
345.0668; found 345.0676.
+
(500 MHz, CDCl3): δ = 7.94 (s, 1 H), 7.78 (d, J = 1.9 Hz, 1 H), 7.61
(dd, J = 8.2, 1.3 Hz, 2 H), 7.57 (t, J = 7.3 Hz, 2 H), 7.51 (dd, J = 10.6,
4.4 Hz, 1 H), 7.37–7.26 (m, 5 H), 6.96 (dd, J = 8.2, 2.0 Hz, 1 H), 6.67
(d, J = 8.3 Hz, 1 H), 3.68 (s, 3 H), 3.01 (s, 1 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 145.92, 145.66, 138.27, 133.96, 132.84, 129.54,
129.16, 128.94, 128.16, 128.13, 126.65, 123.61, 115.60, 114.81,
109.68, 84.54, 75.16, 55.56 ppm. HRMS (ESI-TOF): calcd. for
C22H18N2NaO+ [M + Na]+ 349.1311; found 349.1305.
2-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-1-methyl-1H-
pyrrole (3bk): Yellow solid (120.5 mg, 70 %); m.p. 60–62 °C. 1H NMR
(600 MHz, CDCl3): δ = 7.55 (t, J = 2.1 Hz, 1 H), 7.55–7.53 (m, 1 H),
7.42–7.40 (m, 1 H), 7.40–7.39 (m, 1 H), 7.30–7.29 (m, 1 H), 7.29–7.27
(m, 1 H), 7.25–7.23 (m, 1 H), 7.23–7.21 (m, 1 H), 6.77 (s, 1 H), 6.42
(dd, J = 2.8, 2.1 Hz, 1 H), 6.03–5.98 (m, 1 H), 5.78 (dd, J = 3.6, 1.9 Hz,
1 H), 3.52 (s, 3 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 143.85,
136.39, 135.54, 134.13, 133.76, 130.72, 130.48, 130.18, 128.40,
127.61, 118.60, 106.17, 99.15, 32.92 ppm. HRMS (ESI-TOF): calcd. for
1-(2,5-Dimethoxyphenyl)-2-(diphenylmethylene)hydrazine
(3af): Yellow solid (154.6 mg, 93 %); m.p. 174–175 °C. 1H NMR
(500 MHz, CDCl3): δ = 7.98 (s, 1 H), 7.63–7.58 (m, 2 H), 7.55 (t, J =
7.4 Hz, 2 H), 7.48 (t, J = 7.5 Hz, 1 H), 7.35–7.24 (m, 6 H), 6.64 (d, J =
8.7 Hz, 1 H), 6.29 (dd, J = 8.7, 3.0 Hz, 1 H), 3.81 (s, 3 H), 3.59 (s, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 154.93, 145.09, 139.96,
138.43, 135.09, 132.94, 129.56, 129.15, 128.99, 128.17, 128.03,
126.59, 111.15, 102.94, 99.39, 56.18, 55.71 ppm. HRMS (ESI-TOF):
C18H16Cl2N3 [M + H]+ 344.0716; found 344.0719.
+
2-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-1-methyl-1H-
benzo[d]imidazole (3bl) and (E)-2-{[Bis(4-chlorophenyl)-
methylene]hydrazono}-1-methyl-2,3-dihydro-1H-benzo[d]imid-
azole (3bl′): Yellow solid (148.2 mg, 75 %; 3bl/3bl′ mixture, approx-
imately 4:1 by 1H NMR analysis). 1H NMR (600 MHz, CDCl3): δ = 9.14
(s, 1 H), 7.53–7.46 (m, 2 H × 1, 2 H × 0.3), 7.46–7.42 (m, 2 H × 1,
2 H × 0.3), 7.39–7.33 (m, 2 H × 1, 2 H × 0.3), 7.27 (d, J = 8.3 Hz, 1 H),
7.24–7.20 (m, 2 H), 7.17 (d, J = 7.7 Hz, 1 H), 7.04–7.00 (m, 1 H), 6.97
(d, J = 4.2 Hz, 2 H), 6.90 (d, J = 7.6 Hz, 1 H), 3.95 (s, 3 H × 0.3), 3.31
(s, 3 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 156.12, 152.60, 138.36,
134.22, 134.11, 133.73, 133.24, 131.94, 130.31, 130.23, 130.11,
129.20, 128.67, 128.20, 128.09, 127.92, 122.13, 121.42, 121.18,
117.28, 108.51, 108.31, 107.12, 31.71, 27.75 ppm. HRMS (ESI-TOF):
calcd. for C21H20N2NaO2 [M + Na]+ 355.1417; found 355.1399.
+
1-(2,6-Dimethoxyphenyl)-2-(diphenylmethylene)hydrazine
(3ag): Yellow solid (157.9 mg, 95 %); m.p. 132–134 °C. 1H NMR
(500 MHz, CDCl3): δ = 7.55 (dd, J = 12.0, 4.8 Hz, 5 H), 7.48 (t, J =
7.4 Hz, 1 H), 7.41 (d, J = 7.0 Hz, 2 H), 7.29–7.21 (m, 3 H), 6.91 (t, J =
8.3 Hz, 1 H), 6.58 (d, J = 8.3 Hz, 2 H), 3.84 (s, 6 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 151.57, 147.23, 138.71, 133.34, 129.32, 129.14,
128.88, 127.98, 127.77, 126.53, 123.95, 122.58, 105.68, 56.54 ppm.
HRMS (ESI-TOF): calcd. for C21H20N2NaO2 [M + Na]+ 355.1417;
+
calcd. for C21H17Cl2N4 [M + H]+ 395.0825; found 395.0823.
+
found 355.1409.
5-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-2-(tert-butyl)-
1
1-(Diphenylmethylene)-2-(2,4,6-trimethoxyphenyl)hydrazine pyridine (3bm): White solid (141.4 mg, 71 %); m.p. 181–183 °C. H
(3ah): Yellow solid (170.3 mg, 94 %); m.p. 110–111 °C. 1H NMR
NMR (600 MHz, CDCl3): δ = 8.32 (d, J = 2.7 Hz, 1 H), 7.57 (d, J =
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8.3 Hz, 2 H), 7.46 (d, J = 8.6 Hz, 2 H), 7.40 (dd, J = 8.6, 2.8 Hz, 1 H),
7.38 (s, 1 H), 7.26 (t, J = 8.7 Hz, 4 H), 7.23 (d, J = 8.6 Hz, 1 H), 1.34
(s, 9 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 161.58, 143.00, 138.18,
136.35, 135.82, 134.54, 134.31, 130.54, 130.32, 128.51, 127.60,
CDCl3): δ = 163.75 (d, J = 22.1 Hz), 161.76 (d, J = 20.8 Hz), 145.28,
142.66, 134.58 (d, J = 3.0 Hz), 133.86, 130.95 (d, J = 8.2 Hz), 128.59
(d, J = 3.3 Hz), 127.98 (d, J = 8.0 Hz), 121.42, 119.31, 116.74 (d, J =
21.5 Hz), 115.03 (d, J = 21.8 Hz), 112.23, 109.94, 55.40 ppm. 19F NMR
(470 MHz, CDCl3): δ = –113.04 to –113.18 (m, 1 F), –115.79 to
–115.94 (m, 1 F) ppm. HRMS (ESI-TOF): calcd. for C20H17F2N2O+ [M
+ H]+ 339.1303; found 339.1313.
120.55, 119.11, 36.74, 30.36 ppm. HRMS (ESI-TOF): calcd. for
+
C
22H22Cl2N3 [M + H]+ 398.1185; found 398.1196.
5-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-2-(tert-butyl)-4-
methylpyridine (3bn): White solid (115.5 mg, 56 %); m.p. 160–
162 °C. 1H NMR (600 MHz, CDCl3): δ = 8.87 (s, 1 H), 7.59 (d, J =
1.7 Hz, 1 H), 7.58–7.57 (m, 1 H), 7.50–7.49 (m, 1 H), 7.49–7.47 (m, 1
H), 7.29 (d, J = 1.7 Hz, 1 H), 7.28 (d, J = 1.5 Hz, 2 H), 7.26 (t, J =
2.5 Hz, 1 H), 7.21 (s, 1 H), 6.99 (s, 1 H), 1.93 (s, 3 H), 1.33 (s, 9 H) ppm.
13C NMR (150 MHz, CDCl3): δ = 161.16, 143.41, 136.39, 136.21,
135.77, 134.50, 134.35, 130.35, 130.30, 129.41, 128.52, 127.59,
1-(Di-p-tolylmethylene)-2-(2-methoxyphenyl)hydrazine (3da):
1
Yellow solid (148.7 mg, 90 %); m.p. 154–156 °C. H NMR (500 MHz,
CDCl3): δ = 7.99 (s, 1 H), 7.66 (dd, J = 7.9, 1.2 Hz, 1 H), 7.49 (d, J =
8.2 Hz, 2 H), 7.35 (d, J = 7.7 Hz, 2 H), 7.23 (d, J = 7.9 Hz, 2 H), 7.11
(d, J = 8.0 Hz, 2 H), 6.99–6.93 (m, 1 H), 6.79–6.72 (m, 2 H), 3.67 (s, 3
H), 2.45 (s, 3 H), 2.34 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
145.39, 145.17, 138.78, 137.74, 136.15, 134.48, 130.11, 128.89,
128.82, 126.58, 121.56, 118.87, 112.33, 110.07, 55.55, 21.48,
21.23 ppm. HRMS (ESI-TOF): calcd. for C22H22N2NaO+ [M + Na]+
353.1624; found 353.1614.
120.26, 36.58, 30.36, 16.54 ppm. HRMS (ESI-TOF): calcd. for
+
C
23H24Cl2N3 [M + H]+ 412.1342; found 412.1349.
5-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-2-(tert-butyl)-4-
methoxypyridine (3bo): White solid (130.6 mg, 61 %); m.p. 184–
185 °C. 1H NMR (600 MHz, CDCl3): δ = 8.81 (s, 1 H), 7.59 (s, 1 H),
7.58–7.54 (m, 2 H), 7.51–7.44 (m, 2 H), 7.29–7.28 (m, 1 H), 7.27 (d,
J = 1.3 Hz, 2 H), 7.26 (t, J = 2.2 Hz, 1 H), 6.74 (s, 1 H), 3.78 (s, 3 H),
1.35 (s, 9 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 162.31, 151.49,
142.95, 136.45, 135.42, 134.08, 133.49, 130.44, 130.07, 128.40,
128.07, 127.54, 100.57, 55.16, 37.10, 30.34 ppm. HRMS (ESI-TOF):
calcd. for C23H24Cl2N3O+ [M + H]+ 428.1219; found 428.1211.
1-[Bis(4-methoxyphenyl)methylene]-2-(2-methoxyphenyl)-
hydrazine (3ea): Yellow solid (166.7 mg, 92 %); m.p. 161–163 °C.
1H NMR (500 MHz, CDCl3): δ = 7.95 (s, 1 H), 7.64 (d, J = 7.9 Hz, 1 H),
7.53 (d, J = 8.8 Hz, 2 H), 7.26 (d, J = 8.5 Hz, 2 H), 7.05 (d, J = 8.5 Hz,
2 H), 6.95 (t, J = 6.5 Hz, 1 H), 6.83 (d, J = 8.8 Hz, 2 H), 6.75 (q, J =
7.8 Hz, 2 H), 3.86 (s, 3 H), 3.78 (s, 3 H), 3.66 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 159.89, 159.66, 145.38, 144.83, 134.61, 131.91,
130.44, 128.02, 125.23, 121.58, 118.77, 114.85, 113.57, 112.25,
110.05, 55.54, 55.34, 55.32 ppm. HRMS (ESI-TOF): calcd. for
5-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-2-(tert-butyl)-3-
methoxypyridine (3bp): White solid (145.6 mg, 68 %); m.p. 195–
197 °C. 1H NMR (600 MHz, CDCl3): δ = 7.83 (d, J = 2.1 Hz, 1 H), 7.56
(d, J = 8.3 Hz, 2 H), 7.45 (d, J = 8.6 Hz, 2 H), 7.42 (s, 1 H), 7.28 (s, 1
H), 7.27 (d, J = 2.3 Hz, 2 H), 7.25 (s, 1 H), 7.05 (d, J = 2.0 Hz, 1 H),
3.86 (s, 3 H), 1.36 (s, 9 H) ppm. 13C NMR (150 MHz, CDCl3): δ =
155.10, 149.76, 143.04, 140.00, 136.36, 135.82, 134.32, 130.57,
130.34, 128.55, 127.63, 124.69, 103.84, 54.99, 37.29, 28.86 ppm.
HRMS (ESI-TOF): calcd. for C23H24Cl2N3O+ [M + H]+ 428.1219; found
428.1216.
C22H22N2NaO3 [M + Na]+ 385.1523; found 385.1516.
+
1-(2-Methoxyphenyl)-2-[(4-methoxyphenyl)(phenyl)methyl-
ene]hydrazine (3fa/3fa′): White solid (149.6 mg, 90 %; 3f/3f′ mix-
ture, approximately 1.3:1 by 1H NMR analysis). 1H NMR (500 MHz,
CDCl3): δ = 8.06 (s, 1 H), 7.88 (s, 1 H × 0.7), 7.69–7.63 (m, 1 H × 1, 1
H × 0.7), 7.60 (d, J = 7.6 Hz, 2 H), 7.56–7.51 (m, 4 H × 0.7), 7.46 (t,
J = 7.3 Hz, 1 H × 0.7), 7.36–7.30 (m, 2 H), 7.30–7.21 (m, 3 H × 1, 2
H × 0.7), 7.06 (d, J = 8.4 Hz, 2 H), 7.00–6.92 (m, 1 H × 1, 1 H × 0.7),
6.84 (d, J = 8.6 Hz, 2 H × 0.7), 6.80–6.69 (m, 2 H × 1, 2 H × 0.7), 3.86
(s, 3 H), 3.78 (s, 3 H × 0.7), 3.67 (s, 3 H), 3.63 (s, 3 H × 0.7) ppm. 13C
NMR (125 MHz, CDCl3): δ = 159.84, 159.59, 145.34, 145.27, 144.88,
144.62, 138.92, 134.42, 134.26, 133.21, 131.42, 130.39, 129.40,
128.90, 128.03, 127.81, 127.76, 126.57, 124.91, 121.48, 119.00,
118.76, 114.81, 113.52, 112.32, 112.13, 110.00, 109.97, 55.46, 55.42,
5-{2-[Bis(4-chlorophenyl)methylene]hydrazinyl}-2-(tert-butyl)-4-
phenylpyridine (3bq): White solid (175.5 mg, 74 %); m.p. 230–
231 °C. 1H NMR (600 MHz, CDCl3): δ = 9.05 (s, 1 H), 7.50 (s, 1 H),
7.48–7.46 (m, 1 H), 7.46–7.45 (m, 1 H), 7.35 (d, J = 1.8 Hz, 1 H), 7.34
(d, J = 2.2 Hz, 1 H), 7.33 (dd, J = 5.9, 3.9 Hz, 1 H), 7.27 (dd, J = 10.2,
4.6 Hz, 2 H), 7.25 (t, J = 2.1 Hz, 1 H), 7.24–7.22 (m, 1 H), 7.13–7.09
(m, 2 H), 7.06 (s, 1 H), 7.04–7.00 (m, 2 H), 1.37 (s, 9 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 160.92, 143.41, 135.90, 135.75, 135.30, 134.65,
134.38, 134.16, 133.18, 130.20, 130.01, 129.88, 128.93, 128.43,
128.09, 128.03, 127.35, 118.75, 36.68, 30.30 ppm. HRMS (ESI-TOF):
calcd. for C28H25Cl2N3Na+ [M + Na]+ 496.1318; found 496.1325.
+
55.24, 55.22 ppm. HRMS (ESI-TOF): calcd. for C21H20N2NaO2 [M +
Na]+ 355.1417; found 355.1413.
Ethyl (Z)-2-[2-(2-Methoxyphenyl)hydrazono]-2-phenylacetate
(3ga): Yellow solid (95.5 mg, 64 %); m.p. 87–89 °C. 1H NMR
(500 MHz, CDCl3): δ = 12.49 (s, 1 H), 7.68 (d, J = 7.5 Hz, 2 H), 7.64
(dd, J = 7.4, 1.7 Hz, 1 H), 7.36 (t, J = 7.7 Hz, 2 H), 7.30 (t, J = 7.3 Hz,
1 H), 7.00–6.89 (m, 2 H), 6.86 (d, J = 7.6 Hz, 1 H), 4.35 (q, J = 7.1 Hz,
2 H), 3.90 (s, 3 H), 1.35 (t, J = 7.1 Hz, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 163.52, 146.78, 136.83, 132.75, 128.67, 128.53, 127.86,
127.47, 122.09, 121.46, 113.44, 110.53, 61.00, 55.79, 14.27 ppm.
1-[Bis(4-chlorophenyl)methylene]-2-(2-methoxyphenyl)hydraz-
1
ine (3ba): Yellow solid (168.9 mg, 91 %); m.p. 151–152 °C. H NMR
(500 MHz, CDCl3): δ = 7.96 (s, 1 H), 7.62 (d, J = 7.8 Hz, 1 H), 7.54 (d,
J = 8.1 Hz, 2 H), 7.48 (d, J = 8.4 Hz, 2 H), 7.26 (dd, J = 8.0, 2.6 Hz, 4
H), 6.96 (t, J = 7.5 Hz, 1 H), 6.81 (t, J = 7.6 Hz, 1 H), 6.75 (d, J =
7.9 Hz, 1 H), 3.69 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
145.40, 142.11, 136.75, 135.24, 133.76, 133.67, 130.86, 130.48,
129.98, 128.33, 127.51, 121.47, 119.68, 112.41, 110.03, 55.47 ppm.
HRMS (ESI-TOF): calcd. for C20H17Cl2N2O+ [M + H]+ 371.0712; found
371.0712.
HRMS (ESI-TOF): calcd. for C17H18N2NaO3 [M + Na]+ 321.1210;
+
found 321.1207.
Ethyl (Z)-2-[2-(2-Methoxyphenyl)hydrazono]-2-(p-tolyl)acetate
(3ha): Yellow solid (109.3 mg, 70 %); m.p. 111–113 °C. 1H NMR
(600 MHz, CDCl3): δ = 12.40 (s, 1 H), 7.63 (d, J = 7.0 Hz, 1 H), 7.57
(d, J = 7.5 Hz, 2 H), 7.18 (d, J = 7.4 Hz, 2 H), 6.99–6.90 (m, 2 H), 6.88
(d, J = 7.2 Hz, 1 H), 4.37 (dd, J = 13.6, 6.7 Hz, 2 H), 3.93 (s, 3 H), 2.37
(s, 3 H), 1.36 (t, J = 6.9 Hz, 3 H) ppm. 13C NMR (150 MHz, CDCl3):
δ = 163.58, 146.75, 137.31, 134.04, 132.93, 128.70, 128.60, 128.55,
121.87, 121.47, 113.41, 110.53, 60.92, 55.81, 21.23, 14.26 ppm. HRMS
1-[Bis(4-fluorophenyl)methylene]-2-(2-methoxyphenyl)hydraz-
1
ine (3ca): Yellow solid (152.3 mg, 90 %); m.p. 149–151 °C. H NMR
(500 MHz, CDCl3): δ = 7.91 (s, 1 H), 7.62 (d, J = 7.9 Hz, 1 H), 7.59–
+
7.49 (m, 2 H), 7.39–7.30 (m, 2 H), 7.26 (t, J = 8.2 Hz, 2 H), 7.06–6.88
(ESI-TOF): calcd. for C18H20N2NaO3 [M + Na]+ 335.1366; found
(m, 3 H), 6.82–6.70 (m, 2 H), 3.70 (s, 3 H) ppm. 13C NMR (125 MHz, 335.1357.
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Ethyl (Z)-2-(4-Chlorophenyl)-2-[2-(2-methoxyphenyl)hydraz- (500 MHz, CDCl3): δ = 7.68 (dd, J = 6.6, 2.9 Hz, 2 H), 7.43–7.36 (m,
ono]acetate (3ia): Yellow solid (109.8 mg, 66 %); m.p. 110–112 °C.
4 H), 7.36–7.33 (m, 1 H), 7.31 (dt, J = 4.0, 2.2 Hz, 3 H), 7.05 (d, J =
1H NMR (600 MHz, CDCl3): δ = 12.48 (s, 1 H), 7.64–7.62 (m, 1 H), 7.2 Hz, 1 H), 6.88 (d, J = 7.6 Hz, 1 H), 6.76 (t, J = 7.4 Hz, 1 H), 4.04
7.62–7.58 (m, 2 H), 7.34–7.32 (m, 1 H), 7.32–7.30 (m, 1 H), 6.98–6.93 (s, 2 H), 3.39 (s, 3 H), 2.47 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
(m, 2 H), 6.89–6.86 (m, 1 H), 4.36 (q, J = 7.1 Hz, 2 H), 3.92 (s, 3 H),
δ = 168.70, 159.63, 144.83, 139.65, 136.52, 131.40, 130.18, 128.92,
1.36 (t, J = 7.1 Hz, 3 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 163.24, 128.43, 128.05, 127.98, 127.53, 127.24, 122.43, 120.69, 118.87, 32.52,
31.49, 19.39 ppm. HRMS (ESI-TOF): calcd. for C23H22N3 [M + H]+
+
146.90, 135.33, 133.30, 132.59, 129.87, 128.01, 127.29, 122.39,
121.50, 113.50, 110.64, 61.10, 55.82, 14.24 ppm. HRMS (ESI-TOF): 340.1808; found 340.1791.
calcd. for C17H18ClN2O3 [M + H]+ 333.1000; found 333.0991.
+
(E)-6-Chloro-2-[(diphenylmethylene)hydrazono]-1-methyl-
indoline (4e): Yellow solid (154.7 mg, 86 %); m.p. 164–166 °C. 1H
NMR (500 MHz, CDCl3): δ = 7.68 (dd, J = 7.8, 1.8 Hz, 2 H), 7.45–7.28
(m, 8 H), 7.11 (d, J = 7.8 Hz, 1 H), 6.85 (dd, J = 7.8, 1.7 Hz, 1 H), 6.69
(d, J = 1.5 Hz, 1 H), 4.06 (s, 2 H), 3.09 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 167.22, 160.76, 148.20, 139.32, 136.13, 133.46,
130.04, 129.10, 128.44, 128.07, 128.01, 127.47, 125.00, 124.92,
120.16, 107.52, 31.97, 27.95 ppm. HRMS (ESI-TOF): calcd. for
(E)-1,1-Bis(2-methoxyphenyl)-2-[2-(2-methoxyphenyl)-
hydrazono]-2-phenylethan-1-ol (3ga′): White solid (210.8 mg,
90 %); m.p. 205–207 °C. 1H NMR (600 MHz, CDCl3): δ = 9.32 (s, 1 H),
7.43–7.41 (m, 1 H), 7.33–7.19 (m, 5 H), 7.10–6.99 (m, 4 H), 6.95 (s, 2
H), 6.86–6.82 (m, 1 H), 6.77 (s, 2 H), 6.68–6.65 (m, 2 H), 5.31 (s, 1 H),
3.60 (s, 3 H), 3.56–3.35 (m, 6 H) ppm. 13C NMR (150 MHz, CDCl3):
δ = 157.51, 146.56, 145.76, 140.71, 135.31, 129.53, 129.04, 129.02,
126.50, 126.30, 121.50, 121.14, 118.32, 111.90, 111.72, 110.63, 79.71,
C22H19ClN3 [M + H]+ 360.1262; found 360.1255.
+
55.76, 55.44 ppm. HRMS (ESI-TOF): calcd. for C29H29N2O4 [M + H]+
+
(E)-2-[(Diphenylmethylene)hydrazono]-1-propylindoline (4f):
Yellow solid (164.4 mg, 93 %); m.p. 99–100 °C. 1H NMR (500 MHz,
CDCl3): δ = 7.76–7.63 (m, 2 H), 7.45–7.27 (m, 8 H), 7.23 (d, J = 7.2 Hz,
1 H), 7.17 (t, J = 7.6 Hz, 1 H), 6.87 (t, J = 7.4 Hz, 1 H), 6.71 (d, J =
7.8 Hz, 1 H), 4.10 (s, 2 H), 3.56 (t, J = 7.2 Hz, 2 H), 1.63–1.54 (m, 2
H), 0.82 (t, J = 7.4 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
166.74, 160.04, 146.59, 139.43, 136.44, 130.14, 128.93, 128.38,
128.02, 127.90, 127.54, 127.35, 126.66, 124.50, 120.24, 107.19, 43.20,
469.2122; found 469.2117.
General Procedure for the Preparation of 4 – Synthesis of (E)-
2-[(Diphenylmethylene)hydrazono]-1-methylindoline (4a): To a
stirred solution of 1r (1.0 mmol, 0.13 mL) in dry THF (2.0 mL) in an
oven-dried Schlenk flask under N2 at room temperature was slowly
added tBuLi (1.3
M in hexane, 0.77 mL, 1.0 mmol), and the reaction
mixture was stirred at room temperature for 28 min. The mixture
of 2a (0.5 mmol, 97.1 mg) in dry THF (2.0 mL) was then added
under N2 at room temperature. The resulting mixture was stirred at
room temperature for 2 min, and then H2O (10 mL) was added.
The solution was extracted with CH2Cl2 (3 × 10 mL). The combined
organic extracts were dried with anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The crude product was puri-
fied by flash chromatography on a silica gel column (basic, 300–
400 mesh; petroleum ether/diethyl ether, 10:1 v/v) to give 4a
(147.9 mg, 91 %) as a yellow solid; m.p. 158–160 °C. 1H NMR
(500 MHz, CDCl3): δ = 7.73–7.66 (m, 2 H), 7.41 (d, J = 4.4 Hz, 4 H),
7.40–7.36 (m, 1 H), 7.36–7.32 (m, 3 H), 7.26–7.17 (m, 2 H), 6.91 (t,
J = 7.4 Hz, 1 H), 6.73 (d, J = 7.8 Hz, 1 H), 4.13 (s, 2 H), 3.14 (s, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 167.55, 159.94, 147.00,
139.53, 136.23, 130.15, 128.92, 128.40, 127.99, 127.61, 127.45,
126.57, 124.35, 120.49, 106.91, 32.51, 27.87 ppm. HRMS (ESI-TOF):
+
32.40, 20.39, 11.54 ppm. HRMS (ESI-TOF): calcd. for C24H24N3 [M +
H]+ 354.1965; found 354.1959.
(E)-2-{[Bis(4-chlorophenyl)methylene]hydrazono}-1-methyl-
indoline (4g): Yellow solid (179.4 mg, 91 %); m.p. 181–182 °C. 1H
NMR (500 MHz, CDCl3): δ = 7.59 (d, J = 8.1 Hz, 2 H), 7.39 (d, J =
7.9 Hz, 2 H), 7.34 (d, J = 8.0 Hz, 2 H), 7.30 (d, J = 8.2 Hz, 2 H), 7.26
(d, J = 7.1 Hz, 1 H), 7.24–7.19 (m, 1 H), 6.93 (t, J = 7.2 Hz, 1 H), 6.75
(d, J = 7.6 Hz, 1 H), 4.11 (s, 2 H), 3.15 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 168.25, 157.27, 146.68, 137.54, 134.90, 133.96,
133.89, 131.49, 129.36, 128.18, 127.74, 127.60, 126.36, 124.27,
120.71, 107.03, 32.49, 27.82 ppm. HRMS (ESI-TOF): calcd. for
+
C
22H18Cl2N3 [M + H]+ 394.0872; found 394.0876.
(E)-2-{[Bis(4-methoxyphenyl)methylene]hydrazono}-1-methyl-
indoline (4h): Yellow solid (177.3 mg, 92 %); m.p. 112–114 °C. 1H
NMR (600 MHz, CDCl3): δ = 7.63 (d, J = 8.8 Hz, 2 H), 7.39 (d, J =
8.7 Hz, 2 H), 7.22 (d, J = 7.2 Hz, 1 H), 7.19 (t, J = 6.1 Hz, 1 H), 6.92
(d, J = 8.7 Hz, 2 H), 6.87 (t, J = 8.2 Hz, 3 H), 6.70 (d, J = 7.8 Hz, 1 H),
4.09 (s, 2 H), 3.84 (s, 3 H), 3.81 (s, 3 H), 3.15 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 166.84, 160.48, 159.38, 159.37, 147.19, 132.78,
132.04, 130.05, 128.56, 127.63, 126.66, 124.39, 120.33, 113.44,
112.76, 106.82, 55.37, 55.27, 32.45, 27.92 ppm. HRMS (ESI-TOF):
calcd. for C22H20N3 [M + H]+ 326.1652; found 326.1644.
+
(E)-2-[(Diphenylmethylene)hydrazono]-1,5-dimethylindoline
(4b): Yellow solid (152.7 mg, 90 %); m.p. 154–156 °C. 1H NMR
(500 MHz, CDCl3): δ = 7.72–7.65 (m, 2 H), 7.47–7.28 (m, 8 H), 7.08
(s, 1 H), 7.01 (d, J = 7.8 Hz, 1 H), 6.62 (d, J = 7.9 Hz, 1 H), 4.10 (s, 2
H), 3.13 (s, 3 H), 2.31 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
167.73, 159.56, 144.67, 139.58, 136.25, 130.13, 129.91, 128.80,
128.33, 127.94, 127.90, 127.71, 127.40, 126.64, 125.28, 106.55, 32.48,
27.89, 20.93 ppm. HRMS (ESI-TOF): calcd. for C23H21N3Na+ [M + Na]+
362.1628; found 362.1632.
calcd. for C24H23N3NaO2 [M + Na]+ 408.1682; found 408.1677.
+
Preparation of 6-Chloro-3-(4-chlorophenyl)-1-(2-methoxy-
phenyl)-1H-indazole (5): To a stirred solution of 3ba (0.2 mmol)
and iodobenzene (0.02 mmol) in TFA (2.0 mL) was added potassium
peroxomonosulfate (0.3 mmol) at –10 °C, and the resulting mixture
was stirred at –10 °C for 35 min. After 3ba was consumed (progress
monitored by TLC), the reaction mixture was poured into water
(50 mL) and then extracted with CH2Cl2 (3 × 10 mL). The combined
organic extracts were dried with anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The crude product was puri-
fied by flash chromatography on a silica gel column (basic, 300–
400 mesh; petroleum ether/diethyl ether, 9:1 v/v) to give 5 (44.2 mg,
(E)-2-[(Diphenylmethylene)hydrazono]-5-methoxy-1-methyl-
indoline (4c): Yellow solid (159.9 mg, 90 %); m.p. 186–188 °C. 1H
NMR (500 MHz, CDCl3): δ = 7.68 (dd, J = 6.5, 3.1 Hz, 2 H), 7.44–7.35
(m, 5 H), 7.35–7.31 (m, 3 H), 6.93–6.86 (m, 1 H), 6.74 (dd, J = 8.4,
2.3 Hz, 1 H), 6.61 (d, J = 8.4 Hz, 1 H), 4.12 (s, 2 H), 3.77 (s, 3 H), 3.11
(s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 167.67, 159.34, 154.66,
140.85, 139.61, 136.29, 130.13, 128.75, 128.30, 127.93, 127.86,
127.40, 112.16, 111.75, 106.83, 55.89, 32.81, 27.96 ppm. HRMS (ESI-
TOF): calcd. for C23H21N3NaO+ [M + Na]+ 378.1577; found 378.1573.
(E)-2-[(Diphenylmethylene)hydrazono]-1,7-dimethylindoline 60 %) as a yellow solid; m.p. 205–206 °C. 1H NMR (600 MHz, CDCl3):
(4d): Yellow solid (156.1 mg, 92 %); m.p. 135–137 °C. 1H NMR
δ = 7.93 (d, J = 8.5 Hz, 2 H), 7.90 (d, J = 8.6 Hz, 1 H), 7.52–7.49 (m,
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1 H), 7.49–7.44 (m, 3 H), 7.25–7.23 (m, 1 H), 7.21 (dd, J = 8.6, 1.6 Hz,
1 H), 7.12 (dd, J = 7.6, 6.2 Hz, 2 H), 3.82 (s, 3 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 154.20, 144.80, 142.58, 134.27, 133.11, 131.50,
130.13, 129.06, 128.88, 128.75, 127.73, 122.64, 121.82, 121.21,
120.51, 112.45, 111.34, 55.88 ppm. HRMS (ESI-TOF): calcd. for
C
20H15Cl2N2O+ [M + H]+ 369.0556; found 369.0552.
Acknowledgments
[10]
[11]
Financial support of this research by the National Natural Scien-
ces Foundation of China (21472017), the Natural Sciences Foun-
dation of Jilin Province (20150101065JC), and the Thirteenth
Five-Year Sci-Tech Research Guideline of the Education Depart-
ment of Jilin Province are greatly acknowledged.
Keywords: Arenes · Diazo compounds · Nucleophilic
addition · Regioselectivity · C–N bond formation
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Received: June 18, 2017
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© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim