Tris(pyrazolyl)borate rhodium complexes. Application for reductive amination and esterification of aldehydes in the presence of carbon monoxide

Article abstract of DOI:10.1016/j.jorganchem.2020.121468

The halide complexes TpRhCl₂(MeOH) and Tp^Me2RhI₂(CO) (Tp = hydrotris-(pyrazolyl)borate; Tp^Me2 = hydrotris-(3,5-dimethylpyrazolyl)borate) were synthesized by reactions of RhCl₃ with K[Tp] in methanol and Tp^Me2Rh(CO)₂ with iodine, respectively. Reactions of Tp^Me2RhCl₂(MeOH) and Tp^Me2RhI₂(CO) with 1,10-phenanthroline afford the phenanthroline derivatives [Tp^Me2Rh(phen)X]⁺ (X = Cl, I). The structures of TpRhCl₂(MeOH) and TpRhI₂(CO) were determined by X-ray diffraction. Tris(pyrazolyl)borate rhodium complexes effectively catalyze the reductive amination and the reductive esterification of aldehydes in the presence of carbon monoxide.

Full text of DOI:10.1016/j.jorganchem.2020.121468

Journal Pre-proof
Tris(pyrazolyl)borate rhodium complexes. Application for reductive
amination and esterification of aldehydes in the presence of carbon
monoxide
Vladimir B. Kharitonov , Vladimir S. Ostrovskii , Yulia V. Nelyubina ,
Dmitry V. Muratov , Denis Chusov , Dmitry A. Loginov
PII:
S0022-328X(20)30370-3
DOI:
Reference:
https://doi.org/10.1016/j.jorganchem.2020.121468
JOM 121468
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Journal of Organometallic Chemistry
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Revised date:
Accepted date:
10 July 2020
11 August 2020
12 August 2020
Please cite this article as: Vladimir B. Kharitonov , Vladimir S. Ostrovskii , Yulia V. Nelyubina ,
Dmitry V. Muratov , Denis Chusov , Dmitry A. Loginov , Tris(pyrazolyl)borate rhodium complexes.
Application for reductive amination and esterification of aldehydes in the presence of carbon monoxide,
Journal of Organometallic Chemistry (2020), doi: https://doi.org/10.1016/j.jorganchem.2020.121468
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Highlights
 Tris(pyrazolyl)borate rhodium complexes were synthesized.
 They effectively catalyze reductive amination and esterification of aldehydes in the
presence of carbon monoxide.
 The catalytic activity is dependent on the nature of auxiliary ligands.
 Primary and secondary amines with aromatic and aliphatic substituents are suitable for
the reductive amination.

Tris(pyrazolyl)borate rhodium complexes. Application for reductive amination and
esterification of aldehydes in the presence of carbon monoxide
Vladimir B. Kharitonov,[a] Vladimir S. Ostrovskii,[a] Yulia V. Nelyubina,[a] Dmitry V.
Muratov,[a] Denis Chusov,[a] Dmitry A. Loginov*[a]
Abstract
The halide complexes TpRhCl2(MeOH) and TpMe2RhI2(CO) (Tp = hydrotris-(pyrazolyl)borate;
TpMe2 = hydrotris-(3,5-dimethylpyrazolyl)borate) were synthesized by reactions of RhCl3 with
K[Tp] in methanol and TpMe2Rh(CO)2 with iodine, respectively. Reactions of
TpMe2RhCl2(MeOH) and TpMe2RhI2(CO) with 1,10-phenanthroline afford the phenanthroline
derivatives [TpMe2Rh(phen)X]+ (X = Cl, I). The structures of TpRhCl2(MeOH) and TpRhI2(CO)
were determined by X-ray diffraction. Tris(pyrazolyl)borate rhodium complexes effectively
catalyze the reductive amination and the reductive esterification of aldehydes in the presence of
carbon monoxide.
Keywords: Amines; Carbon monoxide; Hydridotris(pyrazolyl)borate complexes; Reductive
amination; Rhodium
1. Introduction
It is well known that the easy flexibility of the supporting ligand in the catalyst can
considerably increase its catalytic activity. In particular, we have recently found that indenyl
rhodium complexes show high catalytic activity in the reductive amination of aldehydes and
ketones in the presence of carbon monoxide.1 It is an atom- and step-economical approach to
amines, which are of importance for the electronic and pharmaceutical industry.2 The enhanced
catalytic activity of indenyl complexes is attributed to the easy generation of an additional free
coordination site at the metal atom as a result of the slippage of indenyl ligand from η5 to η3
coordination mode.3
Tris(pyrazolyl)borate anions (Tp) are well-known ligands,4 whose metal complexes
easily undergo k3 – k2 isomerization with the release of a free coordination site at the metal atom.
So, the Tp ligand can be coordinated in a bidentate or tridentate fashion.5 This flexibility should
[a] A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
ul. Vavilova 28, 119991 Moscow, Russia
E-mail: dloginov@ineos.ac.ru
http://www.ineos.ac.ru/en
2

enhance the catalytic activity of tris(pyrazolyl)borate metal complexes as compared with
cyclopentadienyl analogs. However, even in the case of rhodium, which is a typical catalytic
metal, only a few examples of the successful application of Tp complexes in catalysis are
known.6 In particular, bis(ethylene) and cyclooctadiene derivatives, TpRh(C2H4)2 and
TpRh(COD), have proved to be effective catalysts for the stereoregular polymerization of para-
substituted phenylacetylenes,7 hydrogenation of quinoline,8 the addition of amines to alkynes,9
the substitution of allylic carbonates by organolithium reagents,10 as well as di- and trimerization
of alkynes.11 Recently, Jones with co-workers have demonstrated the activation of the E–H
bonds (E = B, C, Si, N) with phosphine and isocyanide complexes.12
Herein, we report the first example of the application of tris(pyrazolyl)borate rhodium
complexes as catalysts for the reductive amination and the reductive esterification of aldehydes
in the presence of carbon monoxide. For catalyst screening, we used both rhodium(I) and
rhodium(III) complexes.
2. Results and Discussion
Tris(pyrazolyl)borate rhodium complexes with labile COD and CO ligands
TpMe2Rh(COD) (1) and TpMe2Rh(CO)2 (2) (TpMe2 = hydrotris-(3,5-dimethylpyrazolyl)borate) as
well as derivatives with halide ligands TpMe2RhCl2(MeOH) (3b) and TpRhI2(CO) (4a) were
synthesized by known procedures (Scheme 1).13,14 Complexes TpRhCl2(MeOH) (3a) and
TpMe2RhI2(CO) (4b) were prepared analogously to the methods employed by Powell, Venanzi,
and Cocivera for the synthesis of 3b and 4a.14 It was shown that in wet solvents (such as
dichloromethane and acetone) the methanol ligand in 3b is replaced by water to give
TpMe2RhCl2(H2O) (3c) in almost quantitative yield.
Scheme 1. Tris(pyrazolyl)borate rhodium complexes studied in this work.
3

We found that one of the halide anions in 3b and 4b is also labile and can be easily
displaced. In particular, reactions with 1,10-phenanthroline lead to the cationic complexes
[TpMe2Rh(phen)Cl]+ (5) and [TpMe2Rh(phen)I]+ (6) (Scheme 2). In the case of chlorine
derivative, the reaction is also accompanied by the formation of a sparingly soluble salt
5[TpMe2RhCl3]. Earlier, Powell with co-workers showed that a similar reaction of 3b with 2,2'-
bipyridyl leads to the attachment of two tris(pyrazolyl)borate rhodium moieties to bipyridyl as a
result of the replacement of methanol only,14c which can be explained by greater structural
flexibility of bipyridyl as compared with phenanthroline.
Scheme 2. Reactions of 3b and 4b with 1,10-phenanthroline.
The structures of 3a and 4a were elucidated by X-ray diffraction (Figs. 1 and 2). As
expected, in both compounds the rhodium atom adopts distorted octahedral coordination and the
tris(pyrazolyl)borate ligand is coordinated in a tridentate fashion. In 4a, the CO ligand and the
iodine atoms are disordered by three positions around the three-fold axis passing through the
boron and the rhodium atoms, which precludes any detailed discussion of the Rh–I and Rh–C
distances. The Rh–N and Rh–Cl distances in 3a are close to those in other related
tris(pyrazolyl)borate rhodium complexes.14a,15 At the same time, the Rh–N bonds in 3a (1.991–
2.026 Å, av. 2.006 Å) are shorter than in the carbene derivative TpRhCl2[C(SMe)2] (2.020–2.107
Å, av. 2.051 Å),16 which can be explained by strong -back-donation of the carbene ligand.17
4

Figure 1. General view of compound 3a with atoms shown as thermal ellipsoids at the 50%
probability level. The solvate methanol molecule and hydrogen atoms except those of the BH
and OH groups are omitted for clarity. Selected bond lengths (Å): Rh1–Cl1 2.3469(12), Rh1–Cl2
2.3492(14), Rh1–O1 2.065(3), Rh1–N1a 2.001(4), Rh1–N1b 2.026(4), Rh1–N1c 1.991(4).
Figure 2. General view of compound 4a with atoms shown as thermal ellipsoids at the 50%
probability level. Only one component of the CO ligand and the iodine atoms, which are
5

disordered by three positions around the three-fold axis passing through the boron and the
rhodium atoms, is shown. Hydrogen atoms except one of the BH group are omitted for clarity,
and labels are given only for symmetry-independent atoms. Selected bond lengths (Å): Rh1–I1
2.6476(14), Rh1–C1 1.86(2), Rh1–N1a 2.069(4).
Taking into account the close relation of the rhodium(III) halide complexes 3a,b and 4a,b
to [Cp*RhCl2]2 and Cp*Co(CO)I2, which are well-known catalysts for CH activation,18 we tested
the catalytic ability of the new complexes in the oxidative coupling of benzoic acid with
diphenylacetylene in o-xylene at 150 ºC (Table 1).19 Unfortunately, our attempts were
unsuccessful and all complexes showed very low catalytic activity, giving substituted
naphthalene as the only product. The best yield of 1,2,3,4-tetraphenylnaphthalene (35%) was
achieved using iodide 4a as a catalyst (Table 1, entry 2). Noteworthy, the chloride derivatives
3a,b proved to be almost inactive (entries 3, 4, and 8). The low activity of the
tris(pyrazolyl)borate rhodium complexes may be explained by the presence in their structure of
the tris(pyrazolyl)borate anion, which is a strong donor nitrogen ligand. Earlier, we have found
that N, Nʹ-ligands (such as 2,2'-bipyridyl and 1,10-phenanthroline) can considerably change the
reaction pathway of CH activation.20 The use of methanol as a solvent and more donor 1-phenyl-
1-propyne as a coupling partner as well as the decrease of the reaction temperature to 80 ºC did
not give any positive impact (entries 6–8).
Table 1. The catalytic activity of the tris(pyrazolyl)borate rhodium complexes in the oxidative
coupling of benzoic acid with internal alkynes.
Solvent and
temperature, ºC
o-xylene, 150
o-xylene, 150
o-xylene, 150
o-xylene, 150
o-xylene, 150
o-xylene, 150
Yield,a
%
Entry
Catalyst
Additive
Time
R
1
TpRhI2(CO), 4a
AgOAc
AgOAc
10
24
10
10
10
10
Ph
Ph
Ph
Ph
Ph
Me
16
2
TpRhI2(CO), 4a
35
3
TpMe2RhCl2(MeOH), 3b
TpMe2RhCl2(MeOH), 3b
Tp Me2RhI2(CO), 4b
TpRhI2(CO), 4a
AgOAc
Nd
Nd
12
4b
5c
6c
Cu(OAc)2
Cu(OAc)2
AgOAc
2
6

7
8
TpRhI2(CO), 4a
AgOAc
AgOAc
MeOH, 80
MeOH, 80
10
10
Me
Me
Nd
Nd
TpRhCl2(MeOH), 3a
a Yields are given for the isolated product. Nd = not detected.
The reductive amination of aldehydes catalyzed by the tris(pyrazolyl)borate rhodium
complexes was more successful. Amines are an irreplaceable class of organic compounds, and
reductive amination21 is widely used for the synthesis of industrially important amines22. The
reductive amination without an external hydrogen source provides unique selectivity for this
approach. Carbon monoxide is using as a deoxygenating agent that provides the target amine and
carbon dioxide.23 As model substrates, we chose p-anisidine and 4-tolualdehyde. The catalytic
activity with 1 mol% of the catalysts was very high to find the difference between the complexes
(Table 2, entries 1–3). Therefore, we decided to decrease the catalyst loading to 0.5 mol% (Table
2, entries 4–9). All tris(pyrazolyl)borate rhodium complexes showed higher catalytic activity
compared to Cp2Rh2(CO)3 complex (entries 4–8 vs. 9). The rhodium(I) complex 1 based on the
cyclooctadiene ligand turned out to be less active than the carbonyl derivative 2 (entry 4 vs. 5),
which can be explained by a stronger binding of rhodium with COD as compared with CO. The
rhodium(III) iodide 4b also showed low activity (entry 8). Nevertheless, complex 1 can be used
for this transformation in ethanol with 1 mol% catalyst loading (entry 10). However, for the
complex 4b, even 1 mol% of the catalyst loading is not enough to get a satisfactory yield (entry
12). At the same time, the rhodium(III) chlorides 3b and 3c led to the product with a yield of
more than 90%, even in water (entries 6 and 7). When the catalyst loading is decreased to 0.2
mol%, only traces of the product were detected (entries 13–15). Such a dramatic effect may be
explained by impurities in the starting organic materials, which deactivate catalytic species. The
yield of the product drops dramatically when the pressure was decreased (entries 16–18). At the
same time, the reaction with carbon monoxide at 20 bar under prolonged reaction time can
proceed with preparative yield (entry 16).
Table 2. The catalytic activity of tris(pyrazolyl)borate rhodium complexes in the reductive
amination
Entry
catalyst
Tp Me2Rh(CO)2, 2
Loading catalyst, mol %
Solvent
H2O
Yieldb of 7
99%
1
2
1
1
TpRhCl2(MeOH), 3a
H2O
99%
7

3
4
TpMe2RhI2(CO), 4b
Tp Me2Rh(COD), 1
Tp Me2Rh(CO)2, 2
1
H2O
H2O
H2O
H2O
H2O
H2O
H2O
EtOH
EtOH
EtOH
H2O
H2O
H2O
H2O
H2O
H2O
92%
26%
94%
95%
92%
50%
10%
99%
99%
15%
traces
0%
0.5
5
0.5
6
TpMe2RhCl2(MeOH), 3b
TpMe2RhCl2(H2O), 3c
TpMe2RhI2(CO), 4b
Cp2Rh2(CO)3
0.5
7
0.5
8
0.5
9
0.5
10
11
12
13
14
15
16c
17e
18f
Tp Me2Rh(COD), 1
Tp Me2Rh(CO)2, 2
TpMe2RhI2(CO), 4b
Tp Me2Rh(CO)2, 2
1
1
1
0.2
TpMe2RhCl2(MeOH), 3b
TpMe2RhCl2(H2O), 3c
TpMe2RhCl2(MeOH), 3b
TpMe2RhCl2(MeOH), 3b
TpMe2RhCl2(MeOH), 3b
0.2
0.2
traces
66%d
26%d
3%d
0.5 (20 bar, 20 h)
0.5 (10 bar, 20 h)
0.5 (5 bar, 20 h)
a 40.6 mg (0.33 mmol) p-anisidine, 26 μL (0.22 mmol) 4-tolualdehyde, 200 μL of solvent. b
Yields were determined by NMR. c 20 bar of CO, 20 h. d The average yield of two experiments. e
10 bar of CO, 20 h. f 5 bar of CO, 20 h.
With optimal conditions in hand, we checked the general applicability of different amines
and carbonyl compounds (Scheme 3). The reaction proceeds well with primary and secondary
amines, with aromatic and aliphatic amines, with aldehydes and ketones. The cyclopropyl moiety
and aliphatic chlorides are suitable for the reaction. The only limitation is the combination of
pyrrolidine with aromatic aldehydes. In this case, besides the main product 12, a significant
number of by-products were observed. Even when the catalyst loading was decreased to 0.5
mol% and the reaction time was decreased to 4 hours, only 59% of the product was formed,
while the conversion was 98%.
8

Scheme 3. The substrate scope of the reductive amination using CO as a reducing agent and 3b
as a catalyst.
Finally, we found that the catalytic system can also be applied for the reductive esterification.24
In the case of 3b, the reductive esterification of 4-chlorobenzaldehyde with acetic acid led to a
60% yield of 13 (Scheme 4). This result is comparable to the best catalytic system for this
reaction. The activity of 3b is 120 TON while the best ruthenium-based catalyst has TON 71 per
ruthenium atom,24a and the best rhodium catalyst shows TON 70.24b
Scheme 4. The reductive esterification of 4-chlorobenzaldehyde with acetic acid using CO as a
reducing agent and 3b as a catalyst.
3. Conclusion
In conclusion, the tris(pyrazolyl)borate rhodium complexes were synthesized by simple
procedures starting with rhodium trichloride. Their full characterization was provided. The
trends of the catalytic activity of tris(pyrazolyl)borate rhodium complexes in the reductive
9

amination and the reductive esterification without an external hydrogen source were studied. The
developed catalytic system can be used for the synthesis of secondary and tertiary amines from
aldehydes and ketones. The complex 3b also showed the highest catalytic activity in the
reductive esterification of chlorobenzaldehyde with acetic acid.
4. Experimental section
The reactions were carried out under an inert atmosphere in dry solvents. The isolation of
products was conducted in the air. The starting materials 213 and 3b14c were prepared as
described in the literature. All other reagents were purchased from Acros or Aldrich and used as
1
received. H and 13C{1H} NMR spectra were recorded on a Varian Inova 400 spectrometer
operating at 400.13 and 100.61 MHz, respectively. Chemical shifts are reported in ppm using the
residual signals of the solvents as internal standards. The signals with the apostrophe (ʹ)
correspond to the pyrazolyl ring, which is in the trans-position to the additional auxiliary ligand
(H2O, MeOH, CO, etc.).
4.1. Synthesis of TpRhCl2(MeOH) (3a)
A solution of K[Tp] (478 mg; 1.89 mmol) in MeOH (5 ml) was slowly added to a suspension of
RhCl3∙3H2O (500 mg; 1.9 mmol) in MeOH (1.25 ml). The reaction is quite exothermic, the red
solution turns yellow and then becomes black due to a small amount of rhodium metal formed.
The reaction mixture was refluxed for 4 h. Rhodium was centrifuged off, the solution was
concentrated in vacuo until a precipitate began to form. The solution was left overnight at −30
ºC. The obtained orange crystals were filtered off, crushed and dried in vacuo. Compound 3a
was obtained as a yellow solid (436 mg, 55%). 1H NMR (dmso-d6):  = 8.14 (d, 2H, H5, J=2.4),
8.04 (d, 1H, H5ʹ, J=2.4), 7.96 (q, 1H, CH3OH, J=4.0), 7.86 (d, 2H, H3, J=1.6), 7.68 (d, 1H, H3ʹ,
13
J=1.6), 6.49 (t, 2H, H4, J=2.4), 6.38 (t, 2H, H4ʹ, J=2.4), 3.44 (d, 3H, CH3OH, J=4.0). C{1H}
NMR (dmso-d6):  = 145.45 (s, C3), 143.06 (s, C3ʹ), 137.54 (s, C5), 137.36 (s, C5ʹ), 107.61 (s,
C4), 107.5 (s, C4ʹ), 53.01 (s, CH3OH). HRMS (ESI): calc. for C9H14N7BCl2Rh
[M−MeOH+NH4]+ = 403.9832. Found: 403.9831.
4.2. Synthesis of TpMe2RhCl2(H2O) (3c)
A suspension of 3b complex (50 mg, 0.1 mmol) in wet CH2Cl2 (3 ml) was stirred overnight (an
inert atmosphere is not necessary). The precipitate was centrifuged off and washed with an
additional amount of CH2Cl2. Compound 3c was obtained as a colorless solid (46 mg, 95%). 1H
NMR (dmso-d6):  = 6.60 (s, 2H, H2O), 5.93 (s, 2H, H4), 5.87 (s, 1H, H4ʹ), 2.47 (s, 3H, CH3 at
C3ʹ), 2.45 (s, 6H, CH3 at C3), 2.36 (s, 3H, CH3 at C5ʹ), 2.35 (s, 6H, CH3 at C5). 13C{1H} NMR
10

(dmso-d6):  = 155.34 (s, C3ʹ), 153.71 (s, C3), 144.89 (s, C5’), 144.62 (s, C5), 108.99 (s, C4),
108.73 (s, C4’), 16.08 (s, CH3), 14.56 (s, CH3), 12.67 (s, CH3), 12.44 (s, CH3). HRMS (ESI):
calc. for C15H26N7BCl2Rh [M−H2O+NH4]+ = 488.0772. Found: 488.0756.
4.3. Synthesis of TpMe2RhI2(CO) (4b)
A solution of I2 (109 mg, 0.42 mmol) in ether (8 ml) was added dropwise to a stirred solution of
2 (190 mg, 0.42 mmol) in dichloromethane (9 ml). The reaction mixture was stirred overnight.
The solvent was removed in vacuo. The red residue was washed with water and reprecipitated
from CH2Cl2 with petroleum ether and dried in vacuo. Compound 4b was obtained as a dark-red
solid (235 mg, 82%). IR (KBr, cm-1): ν(BH) = 2533, ν(CO) = 2088. 1H NMR (CDCl3):  = 5.94
(s, 1H, H4ʹ), 5.85 (s, 2H, H4), 2.93 (s, 3H, CH3 at C3ʹ), 2.66 (s, 6H, CH3 at C3), 2.43 (s, 3H, CH3
13
at C5ʹ), 2.36 (s, 6H, CH3 at C5). C{1H} NMR (CDCl3):  = 153.19 (s, C3), 145.25 (s, C3ʹ),
144.63 (s, C5), 136.55 (s, C5ʹ), 109.23 (s, C4), 108.70 (s, C4ʹ), 21.31 (s, CH3), 18.29 (s, CH3),
13
12.92 (s, CH3). The signal of CO was not observed in C{1H} NMR due to its low intensity.
HRMS (ESI): calc. for C19H28N8BIRh [M−CO−I−+2MeCN]+ = 609.0628. Found: 609.0631.
4.4. Synthesis of [TpMe2Rh(phen)Cl]PF6 (5PF6) and [TpMe2Rh(phen)Cl][TpMe2RhCl3]
(5[TpMe2RhCl3])
Benzene (3 ml) was added to a mixture of 3b (50 mg, 0.1 mmol) and 1,10-phenanthroline (20
mg, 0.11 mmol). The reaction mixture was refluxed for 6 h. The solvent was removed in vacuo.
The residue was extracted with methanol. The insoluble residue was washed with acetone and
dried in vacuo to give 5[TpMe2RhCl3] as a colorless solid (33 mg, 59%). An excess of an aqueous
KPF6 solution was added to the solution. The resulting pale pink precipitate was centrifuged off,
washed with water, dried in vacuo, and reprecipitated from acetone with ether to give 5PF6 (20
mg, 26%).
1
5PF6: H NMR (acetone-d6):  = 9.20 (d, 2H, phen, J=8.2), 9.09 (d, 2H, phen, J=5.2), 8.52 (s,
2H, phen), 8.32 (q, 2H, phen, J=5.2), 6.20 (s, 2H, C4), 5.80 (s, 1H, C4ʹ), 2.57 (s, 6H, CH3 at C3),
13
2.51 (s, 3H, CH3 at C3ʹ), 2.46 (s, 6H, CH3 at C5), 0.13 (s, 3H, CH3 at C5ʹ). C{1H} NMR
(acetone-d6):  = 154.85 (s, phen), 153.99 (s), 152.36 (s), 149.21 (s), 146.75 (s), 146.39 (s),
141.40 (s, phen), 131.66 (s), 128.48 (s, phen), 126.41 (s, phen), 110.46 (s, C4), 110.27 (C4ʹ),
15.59 (s, CH3), 11.89 (s, CH3), 11.93 (s, CH3), 10.35 (s, CH3). HRMS (ESI): calc. for
C27H30N8BClRh [M]+ = 615.1429. Found: 615.1442.
1
5[TpMe2RhCl3]: H NMR (dmso-d6):  = 9.17(d, 2H, phen, J=8.0), 8.96 (m, 2H, phen), 8.49 (s,
2H, phen), 8.18 (m, 2H, phen), 6.29 (s, 2H, C4), 5.85 (s, 1H, C4’), 5.81 (s, 3H, C4), 2.59 (s, 9H,
CH3), 2.54 (s, 6H, CH3 at C3), 2.45 (s, 3H, CH3 at C3ʹ), 2.38 (s, 6H, CH3 at C5), 2.35 (s, 9H,
11

13
CH3), 0.01 (s, 3H, CH3 at C5ʹ). C{1H} NMR (dmso-d6):  = 155.08 (s, phen), 154.35 (s),
153.63 (s), 152.03 (s), 148.48 (s), 146.69 (s), 146.54 (s), 143.38 (s), 141.56 (s, phen), 131.16 (s),
128.51 (s, phen), 126.72 (s, phen), 110.58 (s, C4), 110.00 (s, C4’), 108.32 (s, C4), 16.21 (s,
CH3), 15.89 (s, CH3), 12.83 (s, CH3), 12.67 (s, CH3), 12.56 (s, CH3), 10.81 (s, CH3). Anal. Calcd
for С42Н352N14B2Cl4Rh2: C, 44.95; H, 4.67; N, 17.47. Found: C, 44.44; H, 4.80; N, 17.04.
4.5. Synthesis of [TpMe2Rh(phen)I]PF6 (6PF6)
Benzene (3 ml) was added to a mixture of 4b (70 mg, 0.1 mmol) and 1,10-phenanthroline (20
mg, 0.11 mmol). The reaction mixture was refluxed under vigorous stirring for 6 h. The solvent
was removed in vacuo. The residue was extracted with methanol. Then, an excess of aqueous
KPF6 solution was added. The resulting brown precipitate was centrifuged off, washed with
water, dried in vacuo, and reprecipitated from CH2Cl2 with ether. Complex 6PF6 was obtained as
a brown solid (42 mg, 48%). 1H NMR (acetone-d6):  = 9.20 (dd, 2H, phen, J=8.2), 9.07 (d, 2H,
phen, J=5.2), 8.51 (s, 2H, phen), 8.33 (q, 2H, phen, J=5.2), 6.26 (s, 2H, C4), 5.75 (s, 1H, C4ʹ),
2.62 (s, 6H, CH3 at C3), 2.60 (s, 3H, CH3 at C3ʹ), 2.49 (s, 6H, CH3 at C5), 0.04 (s, 3H, CH3 at
C5ʹ). 13C{1H} NMR (acetone-d6):  = 155.55 (s, phen), 154.78 (s), 151.84 (s), 150.79 (s), 147.43
(s), 145.78 (s), 141.43 (s, phen), 131.43 (s, phen), 128.55 (s, phen), 126.70 (s, phen), 110.74 (s,
C4), 110.27 (s, C4ʹ), 20.47 (s, CH3), 12.61 (s, CH3), 12.12 (s, CH3), 10.10 (s, CH3). Anal. Calcd
for С28Н30N8BF6IPRh: C, 38.89; H, 3.50; N, 13.01. Found: C, 39.14; H, 3.88; N, 12.25.
4.6. Synthesis of 4-methoxy-N-(4-methylbenzyl)aniline (7)
Rhodium catalyst 3b (0.56 mg, 0.5 mol%, 1.1 µmol), p-anisidine (40.6 mg, 150 mol %, 0.33
mmol) and p-tolualdehyde (26 μL, 100 mol %, 0.22 mmol) were charged into a glass vial in a 10
ml stainless steel autoclave. 0.2 ml of H2O was added and the autoclave was sealed, flushed three
times with 10 bar of CO, and then charged with 30 bar of CO. The reactor was placed into an oil
bath preheated to 120 °C. After 4 h of heating, the reactor was cooled to room temperature and
depressurized. The reaction mixture was transferred into a flask and the autoclave was washed
with dichloromethane (2×1 ml); the product was extracted with dichloromethane (3×1 ml), the
combined organic layers were filtered through a silica gel pad, the solvent was removed on a
rotary evaporator. 95% yield by NMR.
12

1H NMR (400 MHz, CDCl3):  = 7.28 (d, J = 7.8 Hz, 2H), 7.17 (d, J = 7.8 Hz, 2H), 6.80 (d, J =
9.0 Hz, 2H), 6.62 (d, J = 9.0 Hz, 2H), 4.25 (s, 2H), 3.76 (s, 3H), 2.37 (s, 3H).
NMR spectra are in agreement with the literature data.1c
4.7. Synthesis of N-(cyclohexylmethyl)-4-methoxyaniline (8)
Rhodium catalyst 3b (1.35 mg, 1.2 mol%, 2.6 µmol), p-anisidine (40.6 mg, 150 mol %, 0.33
mmol) and cyclohexanecarboxaldehyde (24.6 mg, 100 mol %, 0.22 mmol) were charged into a
glass vial in a 10 ml stainless steel autoclave. 0.2 ml of water was added and the autoclave was
sealed, flushed three times with 10 bar of CO, and then charged with 30 bar of CO. The reactor
was placed into an oil bath preheated to 120 °C. After 42 h of heating, the reactor was cooled to
room temperature and depressurized. The reaction mixture was transferred into a flask and the
autoclave was washed with dichloromethane (2×1 ml); the product was extracted with
dichloromethane (3×1 ml), the combined organic layers were dried with magnesium sulfate and
filtered through a silica gel pad, the solvent was removed on a rotary evaporator. 99 % yield by
NMR.
1H NMR (300 MHz, CDCl3):  = 6.80 (d, J = 8.9 Hz, 2H), 6.58 (d, J = 8.9 Hz, 2H), 3.75 (s, 3H),
3.50 – 3.20 (br s, 1H), 2.93 (d, J = 6.6 Hz, 2H), 1.90 – 1.80 (d, J = 11.6 Hz, 2H), 1.80 – 1.60 (m,
3H), 1.65 – 1.50 (m, 1H), 1.34 – 1.14 (m, 3H), 1.11 – 0,94 (m, 2H).
NMR spectra are in agreement with the literature data.1c
4.8. Synthesis of 4-(4-methylbenzyl)morpholine (9)
Rhodium catalyst 3b (1.12 mg, 1 mol %, 2.2 µmol), morpholine (28.8 µL, 150 mol %, 0.33
mmol) and p-tolylaldehyde (22 μL, 100 mol %, 0.18 mmol) were charged into a glass vial in a
10 mL stainless steel autoclave. 0.2 ml of water was added and the autoclave was sealed, flushed
three times with 10 bar of CO, and then charged with 30 bar of CO. The reactor was placed into
an oil bath preheated to 120 °C. After 4 h of heating, the reactor was cooled to room temperature
and depressurized. The reaction mixture was transferred into a flask and the autoclave was
13

washed with dichloromethane (2×1 ml); the product was extracted with dichloromethane (3×1
ml), the combined organic layers were dried with magnesium sulfate and filtered through a silica
gel pad, the solvent was removed on a rotary evaporator. 99% yield by NMR (average of two
experiments).
1H NMR (300 MHz, CDCl3):  = 7.22 (d, J = 7.6 Hz, 2H), 7.13 (d, J = 7.6 Hz, 2H), 3.75-3.65
(m, 4H), 3.46 (s, 2H), 2.48-2.37 (m, 4H), 2.34 (s, 3H).
NMR spectra are in agreement with the literature data.1c
4.9. Synthesis of N-isopropyl-4-methoxyaniline (10)
Rhodium catalyst 3b (1.12 mg, 1 mol%, 2.2 µmol), p-anisidine (40.6 mg, 150 mol %, 0.33
mmol) and acetone (16 μL, 100mol%, 0.22 mmol) were charged into a glass vial in a 10 ml
stainless steel autoclave. 0.2 ml of water was added and the autoclave was sealed, flushed three
times with 10 bar of CO, and then charged with 30 bar of CO. The reactor was placed into an oil
bath preheated to 120 °C. After 42 h of heating, the reactor was cooled to room temperature and
depressurized. The reaction mixture was transferred into a flask and the autoclave was washed
with dichloromethane (2×1 ml); the product was extracted with dichloromethane (3×1 ml), the
combined organic layers were filtered through a silica gel pad, the solvent was removed on a
rotary evaporator. 99 % yield by NMR.
1H NMR (300 MHz, CDCl3):  = 6.77 (d, J = 8.9 Hz, 2H), 6.58 (d, J = 8.9 Hz, 2H), 3.75 (s, 3H),
3.55 (sept, J = 6.2 Hz, 1H), 3.20 – 2.96 (br s, 1H), 1.19 (d, J = 6.2 Hz, 6H).
NMR spectra are in agreement with the literature data.1c
4.10. Synthesis of 1-((2,2-dichlorocyclopropyl)methyl)-4-(4-methylbenzyl)piperazine (11)
Rhodium
catalyst
3b
(1.12
mg,
1
mol%,
2.2
µmol),
1-((2,2-
dichlorocyclopropyl)methyl)piperazine (69 mg, 100 mol %, 0.33 mmol) and p-tolualdehyde(26
14

μL, 100 mol %, 0.22 mmol) were charged into a glass vial in a 10 ml stainless steel autoclave.
0.2 ml of H2O was added and the autoclave was sealed, flushed three times with 10 bar of CO,
and then charged with 30 bar of CO. The reactor was placed into an oil bath preheated to 120 °C.
After 22 h of heating, the reactor was cooled to room temperature and depressurized. The
reaction mixture was transferred into a flask and the autoclave was washed with dichloromethane
(2×1 ml); the product was extracted with dichloromethane (3×1 ml), the combined organic layers
were filtered through a silica gel pad, the solvent was removed on a rotary evaporator. 80 %
yield by NMR (average of two experiments).
1H NMR (400 MHz, CDCl3):  = 7.20 (d, J = 7.7 Hz, 2H), 7.12 (d, J = 7.7 Hz, 2H), 3.48 (s, 2H),
2.67-2.58 (m, 6H) 2.55-2.45 (m, 4H), 2.33 (s, 3H), 1.80-1.72 (m, 1H), 1.66-1.62 (m, 1H), 1.13-
1.09 (m, 1H).
NMR spectra are in agreement with the literature data.1b
4.11. Synthesis of 1-(4-methylbenzyl)pyrrolidine (12)
Rhodium catalyst 3b (0.56 mg, 0.5 mol%, 1.1 µmol), pyrrolidine (27 μL, 150 mol %, 0.33
mmol) and p-tolylaldehyde (26 μL, 100 mol %, 0.22 mmol) were charged into a glass vial in a
10 ml stainless steel autoclave. 0.2 ml of water was added and the autoclave was sealed, flushed
three times with 10 bar of CO, and then charged with 30 bar of CO. The reactor was placed into
an oil bath preheated to 120 °C. After 4 h of heating, the reactor was cooled to room temperature
and depressurized. The reaction mixture was transferred into a flask and the autoclave was
washed with dichloromethane (2×1 ml); the product was extracted with dichloromethane (3×1
ml), the combined organic layers were dried with magnesium sulfate and filtered through a silica
gel pad, the solvent was removed on a rotary evaporator. 59% yield by NMR (average of two
experiments).
1H NMR (400 MHz, CDCl3):  = 7.24 (d, J = 7.8 Hz, 2H), 7.14 (d, J = 7.8 Hz, 2H), 3.60 (s, 2H),
2.56 – 2.44 (m, 4H), 2.35 (s, 3H), 1.84 – 1.75 (m, 4H).
NMR spectra are in agreement with the literature data25.
4.12. Synthesis of 4-Chlorobenzyl Acetate (13)
15

Rhodium catalyst 3b (2.52 mg, 0.5 mol%, 5.0 µmol), 4-chlorobenzaldehyde (70.28 mg, 100 mol
%, 0.50 mmol) acetic acid (143 µL, 500 mol%, 2.50 mmol) and water (45 µL, 500 mol %, 2.50
mmol) were charged into a glass vial in a 10 ml stainless steel autoclave. 0.17 ml of toluene was
added and the autoclave was sealed, flushed three times with 10 bar of CO, and then charged
with 30 bar of CO. The reactor was placed into an oil bath preheated to 160 °C. After 44 h of
heating, the reactor was cooled to room temperature and depressurized. The reaction mixture was
transferred into a flask and the autoclave was washed with dichloromethane (2×1 ml); the
product was extracted with dichloromethane (3×1 ml), the combined organic layers were dried
with magnesium sulfate and filtered through a silica gel pad, the solvent was removed on a rotary
evaporator. 60% yield by NMR.
1H NMR (300 MHz, CDCl3):  = 7.28 (two apparent d, J = 8.2 Hz, appears as dd, 4H), 5.04 (s,
2H), 2.07 (s, 3H).
NMR spectra are in agreement with the literature data.24b
4.13. X-ray crystallography
Crystals of 3a∙MeOH were obtained by slow evaporation of its methanol solution.
Crystals of 4a were obtained by slow diffusion in a two-layer system, a mixture of
petroleum ether / solution of complex in dichloromethane. X-ray diffraction data were
collected at 120 K with APEX2 DUO CCD diffractometer, using graphite
monochromated Mo-K
 radiation ( = 0.71073 Å, 
-scans). Using Olex2,26 the
structures were solved with the ShelXT structure solution program27 using Intrinsic
Phasing and refined with the XL refinement package28 using Least Squares minimization.
Hydrogen atoms of the OH and BH groups were located from a difference Fourier
synthesis, positions of other hydrogen atoms were calculated, and they all were refined in
the isotropic approximation within the riding model. Crystallographic data and structure
refinement parameters for 3a and 4a are listed in Table 3.
Table 3
Crystallographic data and structure refinement parameters for 3a∙MeOH and 4a.
Compound
3a∙MeOH
4a
Empirical formula
Molecular weight
Crystal system
Space group
C11H18BCl2N6O2Rh
450.93
C10H10BI2N6ORh
597.76
Orthorhombic
Pna21
Trigonal
P-3
16

a (Å)
17.5961(14)
11.538(5)
b (Å)
7.7777(6)
11.538(5)
c (Å)
12.6395(10)
8.392(3)
90
90
 (deg)
90
90
 (deg)
90
120
 (deg)
V (Å3)
1729.8(2)
967.5(9)
Z
4
2
Dcalcd (g cm–3)
1.732
2.052
58
58
2max (deg)
(Mo-K) (cm–3)
Collected reflections
Independent reflections
Observed reflections (I > 2(I))
Parameters
13.12
40.78
20300
12161
4595 (Rint = 0.0524)
1733 (Rint = 0.0576)
4078
210
1530
74
R (on F for obs. refls)
1
0.0305
0.0420
2
0.0609
0.1073
wR (on F for all refls)
2
F(000)
904
552
GOF
1.042
1.045
Largest diff. peak and hole (e Å–3)
0.935 and −0.723
1.197 and −1.096
Acknowledgements
This work was supported by the Russian Science Foundation (Grant No. 19-73-20212). The
NMR studies were performed with the financial support from the Ministry of Science and Higher
Education of the Russian Federation using the equipment of the Center for molecular
composition studies of INEOS RAS.
Appendix A. Supplementary material
Copies of NMR spectra for the tris(pyrazolyl)borate rhodium complexes.
CCDC 2000123 and 2000124 contain the supplementary crystallographic data for 3a∙MeOH and
4a, respectively. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
17

Declaration of interests
X☐The authors declare that they have no known competing financial interests or personal relationships that could
have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests:
GRAPHICAL ABSTRACT
References
1 a) V.B. Kharitonov, D.V. Muratov, D.A. Loginov, Coord. Chem. Rev. 399 (2019) 213027; b)
V.B. Kharitonov, M. Makarova, M.A. Arsenov, Y.V. Nelyubina, O. Chusova, A.S. Peregudov,
S.S. Zlotskii, D. Chusov, D.A. Loginov, Organometallics 37 (2018) 2553–2562; c) S.A.
Runikhina, M.A. Arsenov, V.B. Kharitonov, E.R. Sovdagarova, O. Chusova, Y.V. Nelyubina,
G.L. Denisov, D.L. Usanov, D. Chusov, D.A. Loginov, J. Organomet. Chem. 867 (2018) 106–
112.
2 a) E. Podyacheva, O.I. Afanasyev, A. A. Tsygankov, M. Makarova, D. Chusov, Synthesis 51
(2019) 2667–2677; b) V.B. Kharitonov, E. Podyacheva, Y.V. Nelyubina, D.V. Muratov, A.S.
Peregudov, G. Denisov, D. Chusov, D.A. Loginov, Organometallics 38 (2019) 3151–3158; c)
A.A. Tsygankov, M. Makarova, D. Chusov, Mendeleev Commun. 28 (2018) 113–122.
3 a) M.J. Calhorda, C.C. Romao, L.F. Veiros, Chem.- Eur. J. 8 (2002) 868−875; b) M.J.
Calhorda, L.F. Veiros, Coord. Chem. Rev. 185−186 (1999) 37−51; c) C. Bonifaci, A. Ceccon, A.
Gambaro, P. Ganis, S. Santi, G. Valle, A. Venzo, Organometallics 12 (1993) 4211−4214.
18

4 a) M. Sallmann, C. Limberg, Acc. Chem. Res. 48 (2015) 2734−2743; b) H.V.R. Dias, C.J.
Lovely, Chem. Rev. 108 (2008) 3223−3238; c) C. Slugovc, I. Padilla-Martinez, S. Sirol, E.
Carmona, Coord. Chem. Rev. 213 (2001) 129−157; d) S. Trofimenko, Chem. Rev. 93 (1993)
943−980.
5 a) R. Criado, M. Cano, J.A. Campo, J.V. Heras, E. Pinilla, M.R. Torres, Polygedron 23 (2004)
301−309; b) A. Albinati, M. Bovens, H. Rueegger, L.M. Venanzi, Inorg. Chem. 36 (1997)
5991−5999; c) N.G. Connelly, D.J.H. Emslie, B. Metz, A.G. Orpen, M.J. Quayle, Chem.
Commun. (1996) 2289−2290.
6 For the most outstanding works, see: a) A.M. Geer, Á.L. Serrano, B. de Bruin, M.A. Ciriano,
C. Tejel, Angew. Chem. Int. Ed. 54 (2014) 472–475; b) J. Yang, A. Sabarre, L.R. Fraser, B.O.
Patrick, J.A. Love, J. Org. Chem. 74 (2009) 182–187; c) C. Cao, L.R. Fraser, J.A. Love, J. Am.
Chem. Soc. 127 (2005) 17614–17615.
7 a) A.M. Trzeciak, J.J. Ziolkowski, Appl. Organometal. Chem. 18 (2004) 124–129; b) H.
Katayama, K. Yamamura, Y. Miyaki, F. Ozawa, Organometallics 16 (1997) 4497–4500.
8 Y. Alvarado, M. Busolo, F. Lopez-Linares, J. Mol. Cat. A: Chem. 142 (1999) 163–167.
9 Y. Fukumoto, H. Asai, M. Shimizu, N. Chatani, J. Am. Chem. Soc. 129 (2007) 13792–13793.
10 P.A. Evans, D. Uraguchi, J. Am. Chem. Soc. 125 (2003) 7158–7159.
11 G. Bottari, L.L. Santos, C.M. Posadas, J. Campos, K. Mereiter, M. Paneque, Chem. Eur. J. 22
(2016) 13715–13723.
12 a) J. Yuwen, W.W. Brennessel, W.D. Jones, Inorg. Chem. 58 (2019) 557–566; b) A.M.
Parsons, W.D. Jones, Dalton Trans. 48 (2019) 10945–10952; c) J. Guan, A. Wriglesworth, X.Z.
Sun, E.N. Brothers, S.D. Zarić, M.E. Evans, W.D. Jones, M. Towrie, M.B. Hall, M.W. George,
J. Am. Chem. Soc. 140 (2018) 1842–1854; d) J. Yuwen, Y. Jiao, W.W. Brennessel, W.D. Jones,
Inorg. Chem. 55 (2016) 9482–9491; e) B. Procacci, Y. Jiao, M.E. Evans, W.D. Jones, R.N.
Perutz, A.C. Whitwood, J. Am. Chem. Soc. 137 (2015) 1258–1272.
13 U.E. Bucher, A. Currao, R. Nesper, H. Rueegger, L.M. Venanzi, E. Younger, Inorg. Chem. 34
(1995) 66–74.
14 a) A. Albinati, U.E. Bucher, V. Gramlich, O. Renn, H. Rueegger, L.M. Venanzi, Inorg. Chim.
Acta 284 (1999) 191–204; b) M. Cocivera, T.J. Desmond, G. Ferguson, B. Kaitner, F.J. Lalor,
D.J. O'Sullivan, Organometallics 1 (1982) 1125–1132; c) S. May, P. Reinsalu, J. Powell, Inorg.
Chem. 19 (1980) 1582–1589.
15 A. Fehn, S. Mihan, K. Polborn, W. Beck, Z. Anorg. Allg. Chem. 623 (1997) 665–675.
16 A.F. Hill, A.J.P. White, D.J. Williams, J.D.E.T. Wilton-Ely, Organometallics 17 (1998) 3152–
3154.
19

17 N.S. Antonova, J.J. Carbo, J.M. Poblet, Organometallics 28 (2009) 4283–4287.
18 For selected recent works, see: a) R. Yoshimura, K. Tanaka, Chem. Eur. J. 26 (2020) 4969–
4973; b) C. Maeng, J.-Y. Son, S.C. Lee, Y. Baek, K. Um, S.H. Han, G.H. Ko, G.U. Han, K. Lee,
K. Lee, P.H. Lee, J. Org. Chem. 85 (2020) 3824–3837; c) R. Yoshimoto, Y. Usuki, T. Satoh,
Chem. Asian J. 15 (2020) 802–806; d) E.A. Trifonova, A.A. Komarova, D. Chusov, D.S.
Perekalin, Synlett 31 (2020) 1117–1120; e) M.M. Vinogradov, D.V. Vorobyeva, Y.V.
Nelyubina, S.N. Osipov, D.A. Loginov, Mendeleev Commun. 30 (2020) 494–495; f) X. Shi, W.
Xu, R. Wang, X. Zeng, H. Qiu, M. Wang, J. Org. Chem. 85 (2020) 3911–3920; g) R. Mei, U.
Dhawa, R.C. Samanta, W. Ma, J. Wencel‐Delord, L. Ackermann, ChemSusChem 13 (2020)
3306–3356; h) A. Baccalini, S. Vergura, P. Dolui, G. Zanoni, D. Maiti, Org. Biomol. Chem. 17
(2019) 10119–10141; i) H. Chen, L. Ouyang, J. Liu, W.-J. Shi, G. Chen, L. Zheng, J. Org.
Chem. 84 (2019) 12755–12763.
19 a) A.P. Molotkov, M.A. Arsenov, D.A. Kapustin, D.V. Muratov, N.E. Shepel’, Y.V. Fedorov,
A.F. Smol’yakov, E.I. Knyazeva, D.A. Lypenko, A.V. Dmitriev, A.E. Aleksandrov, E.I.
Maltsev, D.A. Loginov, ChemPlusChem 85 (2020) 334–345; b) D.A. Loginov, V.E. Konoplev,
J. Organomet. Chem. 867 (2018) 14−24; c) Y. Honjo, Y. Shibata, E. Kudo, T. Namba, K.
Masutomi, K. Tanaka, Chem. Eur. J. 24 (2018) 317–321; d) V. P. Datsenko, Y. V. Nelyubina, A.
F. Smol'yakov, D. A. Loginov, J. Organomet. Chem. 874 (2018) 7−12; e) D. A. Loginov, D. V.
Muratov, Y. V. Nelyubina, J. Laskova, A.R. Kudinov, J. Mol. Catal. A: Chemical 426 (2017)
393–397; f) E. Kudo, Y. Shibata, M. Yamazaki, K. Masutomi, Y. Miyauchi, M. Fukui, H.
Sugiyama, H. Uekusa, T. Satoh, M. Miura, K. Tanaka, Chem. Eur. J. 22 (2016) 14190–14194; g)
D.A. Loginov, A.O. Belova, A.V. Vologzhanina, A.R. Kudinov, J. Organomet. Chem. 793
(2015) 232–240; h) M. Shimizu, K. Hirano, T. Satoh, M. Miura, J. Org. Chem. 74 (2009) 3478–
3483; i) K. Ueura, T. Satoh, M. Miura, J. Org. Chem. 72 (2007) 5362–5367.
20 a) G.B. Shul’pin, D.A. Loginov, L.S. Shul’pina, N.S. Ikonnikov, V.O. Idrisov, M.M.
Vinogradov, S.N. Osipov, Y.V. Nelyubina, P.M. Tyubaeva, Molecules 21 (2016) 1593; b) S.S.
Kuvshinova, A.F. Smol'yakov, D.V. Vorobyeva, S.N. Osipov, D.A. Loginov, Mendeleev
Commun. 28 (2018) 359–361.
21 a) A.Y. Sukhorukov, Front. Chem. 8 (2020) 215; b) C. Nogues, G. Argouarch,
ChemistrySelect 5 (2020) 8319–8327; c) H. Alinezhad, H. Yavari, F. Salehian, Curr. Org. Chem.
19 (2015) 1021–1049; d) T. C. Nugent, M. El-Shazly, Adv. Synth. Catal. 352 (2010) 753–819; e)
P. Zhou, Z. Zhang, L. Jiang, C. Yu, K. Lv, J. Sun, S. Wang, Appl. Catal. B Environ. 210 (2017)
522–532.
22 O. I. Afanasyev, E. Kuchuk, D. L. Usanov, D. Chusov, Chem. Rev. 119 (2019) 11857–11911.
20

23 D. Chusov, B. List, Angew. Chem. Int. Ed. 53 (2014) 5199–5201.
24 a) S.A. Runikhina, D.L. Usanov, A.O. Chizhov, D. Chusov, Org. Lett. 20 (2018) 7856–7859;
b) V.S. Ostrovskii, S.A. Runikhina, O.I. Afanasyev, D. Chusov, Eur. J. Org. Chem. (2020)
4116–4121.
25 O.I. Afanasyev D.L. Usanov, D. Chusov, Org. Biomol. Chem, 15 (2017) 10164–10166.
26 O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl. Cryst. 42
(2009) 339–341.
27 G.M. Sheldrick, Acta Cryst. A71 (2015) 3–8.
28 G.M. Sheldrick, Acta Cryst. A64 (2008) 112–122.
21