Synthesis of O,N,O[sbnd]P multidentate ligands and the formation of early–late heterobimetallic complexes

Article abstract of DOI:10.1016/j.ica.2017.11.027

A multidentate O,N,O[sbnd]P ligand 4 designed for early–late heterobimetallic (ELHB) complexes was synthesized. The ligand 4 has an O,N,O-tridentate ligand moiety and a triarylphosphine group. The O,N,O-moiety based on lutidine scaffold selectively coordinated to early transition metals such as titanium and niobium in the reaction with the corresponding metal alkoxides to form mononuclear complexes. Coordination of the triarylphosphine moiety to the niobium atom was negligible in the Nb-ONO[sbnd]P complex according to ³¹P NMR spectroscopy, whereas a part of the phosphorus atom coordinated to the titanium atom in the Ti-ONO[sbnd]P complex. Addition of [PdCl(π-allyl)]₂ or [RhCl(cod)]₂ to the Nb-ONO[sbnd]P complex gave rise to the formation of ELHB complexes. Thus, the one-pot preparation of ELHB complexes was achieved by simple procedure.

Full text of DOI:10.1016/j.ica.2017.11.027

Inorganica Chimica Acta 471 (2018) 355–363
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Research paper
Synthesis of O,N,OAP multidentate ligands and the formation of
early–late heterobimetallic complexes
⇑
Noriyuki Suzuki , Satoru Yoneyama, Keisuke Shiba, Takeshi Hasegawa, Yoshiro Masuyama
Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 19 August 2017
Received in revised form 12 November 2017
Accepted 15 November 2017
Available online 21 November 2017
A multidentate O,N,OAP ligand 4 designed for early–late heterobimetallic (ELHB) complexes was synthe-
sized. The ligand 4 has an O,N,O-tridentate ligand moiety and a triarylphosphine group. The O,N,O-moiety
based on lutidine scaffold selectively coordinated to early transition metals such as titanium and niobium
in the reaction with the corresponding metal alkoxides to form mononuclear complexes. Coordination of
the triarylphosphine moiety to the niobium atom was negligible in the Nb-ONOAP complex according to
3
1
P NMR spectroscopy, whereas a part of the phosphorus atom coordinated to the titanium atom in the
Ti-ONOAP complex. Addition of [PdCl( -allyl)] or [RhCl(cod)] to the Nb-ONOAP complex gave rise to
Keywords:
Heterobimetallic complex
Niobium
Palladium
Multidentate ligand
p
2
2
the formation of ELHB complexes. Thus, the one-pot preparation of ELHB complexes was achieved by
simple procedure.
Ó 2017 Elsevier B.V. All rights reserved.
1
. Introduction
Cooperative effects of early and late transition metals in cat-
still pursued. Hence, the development of simple protocols for
preparation of ELHB complexes is considered important. The one-
pot synthesis of ELHB complexes must be convenient, particularly
with regard to practical usage for catalytic reactions.
We previously reported on the preparation of multidentate O,N,
OAN,N ligands 1 and selective formation of titanium-palladium
complexes 3 (Scheme 1) [52]. We employed O,N,O-tridentate
ligands that have a lutidine scaffold to construct the Ti-coordinated
moiety [53,54–63].
alytic reactions have received much attention because they could
be utilized to achieve novel, highly selective synthetic reactions.
Early–late heterobimetallic (ELHB) complexes must be one of the
most promising ways to realize synergy effects. There are many
reports on the synthesis of ELHB complexes [1–25]. There are also
many examples of successful cooperative effects resulting from
two metals in a heterobimetallic complex in catalytic reactions
4
We found that titanium tetraisopropoxide [Ti(Oi-Pr) ] selec-
[
9,14,17,26–39].
tively reacted with the O,N,O-tridentate ligands 1 to form the tita-
nium complex 2 at room temperature (rt) due to the oxophilicity of
the early transition metal. Simply adding bis(benzonitrile)palla-
dium dichloride to a solution of 2 resulted in the quantitative for-
mation of 3 at ambient temperature. The di(pyridin-2-yl)methyl
group, a bidentate ancillary nitrogen ligand, in 1 selectively coordi-
nated to palladium by exchanging with benzonitrile. However, to
date, our attempts to synthesize ELHB complexes with other late
transition metals such as Ni and Rh have been unsuccessful. We
postulated that one possible reason for this problem is the coordi-
nation of the pyridyl group on the side arm to the Ti atom in 2.
Thus, we next designed multidentate ligands 4 that possess a
phosphine moiety, because triarylphosphine is widely used, in
many catalytic reactions, as ancillary ligand with various late tran-
sition metals. Here we report on the synthesis of O,N,OAP multi-
dentate ligands 4 and the preparation of Nb–Pd and Nb–Rh
complexes using the ligand (Fig. 1) [64–80].
It has been demonstrated that novel catalytic reactions can be
accomplished by using well designed ligands. For example, the
interaction between the ligand and the substrate can control the
conformation where the metal center selectively activates the
specific position of the substrate [29–32,40–51].
Thus, for ELHB complexes, ligand design is very important to
realize the cooperative effects. The ligand should be designed so
that the two metals are located at an appropriate distance from
each other. Multidentate ligands are useful for constructing ELHB
complexes, although they have to coordinate to two different
metal atoms selectively [19]. Some of ELHB complexes, however,
involves tedious preparative methods and suffers from low selec-
tivity and low yields. Although many ELHB complexes can be syn-
thesized in a straightforward fashion, simple protocols should be
⇑
Corresponding author.
E-mail address: norisuzuki@sophia.ac.jp (N. Suzuki).
Attempts to use them in catalytic reactions are also described.
https://doi.org/10.1016/j.ica.2017.11.027
020-1693/Ó 2017 Elsevier B.V. All rights reserved.
0

3
56
N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
Scheme 2. Preparation of the O,N,O-tridentate ligand scaffold 6. (i) 1 eq n-BuLi at
78 °C, 2.5 h, then 1 eq R
ꢀ
2
C@O, rt, overnight in THF; (ii) 2 eq n-BuLi, ꢀ78 °C to ꢀ20
°
C, 5 h, then 1.2 eq 2-bromobenzaldehyde, ꢀ78 °C to rt, 2 h.
The O,N,OAP ligands 4 showed single signal at ꢀ6 ppm showing
triarylphosphine(III) character. The molecular structure of 4b was
determined by X-ray diffraction study. It clearly showed that tri-
arylphosphine moiety was bound to the O,N,O-ligand part (Fig. 2).
2.2. Preparation of titanium and niobium complexes of 4
Scheme 1. The O,N,OAN,N multidentate ligands 1 and Ti-Pd heterobimetallic
complexes.
We previously reported that the [ONOANN]Ti(OR)
were obtained from the ligand 1 and Ti(Oi-Pr)
2
complexes
4
by alcohol
2
exchange reactions [52]. In the present study we added Ti(Oi-Pr)
to the benzene solution of 4 (Scheme 5). We employed 4b because
a was less soluble in common organic solvents. The benzene solu-
4
4
tion was stirred for 1 h at rt, and volatiles were removed in vacuo.
1
H NMR spectroscopy of the residue suggested the quantitative
formation 9 [82]. Two isopropoxy groups were observed, and one
of the methylene signals of 4b shifted downfield significantly. Sig-
nals of the pyridine ring shifted upfield. These changes in the
chemical shifts were similar to those observed in the reaction
between the ligand 1 and Ti(Oi-Pr)
methine proton of isopropoxy groups were observed at 5.03 and
.18 ppm. Besides, there found a broad signal at 4.52 ppm, imply-
4
. Two septets assignable to
5
ing that free isopropanol coordinates to the titanium atom to form
six-coordinated complex. Two diastereomeric configuration are
possible owing to the presence of chiral carbon, and interchange
between these two in solution might cause broadening the
Fig. 1. The O,N,OAP multidentate ligands 4 and its ELHB complexes.
2
. Results and discussion
methine signals. We also carried out the reaction of niobium(V)
1
5
ethoxide, Nb(OEt) , and 4b. The H NMR spectra of the reaction
2
.1. Preparation of O,N,OAP ligands
mixture suggested the formation of the Nb complex 10. Liberated
ethanol was observed, and inequivalent ethoxy groups were also
found. The signals of the O,N,OApyridine shifted similarly to the
In this study, we decided to use a monodentate phosphine
3
1
ligand as an ancillary ligand for late transition metals. In solution,
a monodentate ligand bound to the O,N,O-complex would be in an
equilibrium between coordination to the metal to form an ELHB
complex and dissociation. We envisioned that the formation of
heterobimetallic complexes in solution with monodentate ligand
moiety might be effective for catalytic reactions. We employed a
benzene ring as a spacer to install a phosphine ligand.
Ti case. In P NMR spectroscopy of 9 and 10, a major signal
appeared at ꢀ5 ppm indicating that most of the phosphorus atoms
have no interaction with the metal. A minor signal was observed at
27 ppm. The integration ratios of the major and minor signals were
74/26 in 9 and 91/9 in 10.
The 31P NMR of the phosphine oxide 8 appeared at 30 ppm.
Thus, it is likely that these signals represent the oxidized species
In the previous studies, the O,N,O-tridentate ligands 1 were pre-
pared from 2,6-lutidine [55,56,60,81].
We now adopted the same methodology to synthesize O,N,OAP
multidentate ligand 4 bearing a phosphine ligand on one of the
alkoxide arms. Mono-ols 5a and 5b were prepared from 2,6-luti-
dine by lithiation and subsequent reactions with the corresponding
ketones. The mono-ols 5 were again treated with two equiv of n-
butyllithium, and then reacted with 2-bromobenzaldehyde to
afford the diols 6 (Scheme 2).
On the other hand, phosphine oxide 7 was prepared from
p-dibromobenzene via stepwise phosphination and borylation fol-
lowed by oxidation (Scheme 3). Finally, Suzuki-Miyaura coupling
between 6 and 7 afforded 8, and subsequent reduction of 8 with
phenylsilane gave the O,N,OAP ligand 4 (Scheme 4). 31P NMR spec-
Scheme 3. Preparation of phosphine oxide 7. (i) 1 eq n-BuLi, ꢀ78 °C, 1 h; (ii) 1 eq
Ph
2
PCl, ꢀ78 °C, 2 h, then rt 1 h; (iii) 1.1 eq n-BuLi, ꢀ78 °C, 1 h; (iv) 1.3 eq i-PrOBpin,
troscopy of the phosphine oxide 8 showed single signal at 30 ppm,
which is characteristic for aryl phosphine oxide.
ꢀ
78 °C, 0.5 h, then rt, 2.5 h in THF; (v) FeCl
3
ꢁ6H
2 2
O 10 mol%, KSCN 30 mol%, O , 80 °C,
22 h in CH CN.
3

N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
357
phine signal was observed at 31.5 ppm in 31P NMR as a doublet
1
being coupled with rhodium (JRh-P = 157 Hz). The
H and
3
1
P NMR spectra showed good correspondence with the spectro-
scopic data of ClRh(cod)PPh [80], suggesting the formation of
2. A minor signal at 25 ppm observed in the P NMR spectrum
3
3
1
1
of 10 remained intact in those of 11 and 12, supporting that the
signals are assignable to phosphine oxides.
It should be noted that the ELHB complexes 11 and 12 can be
prepared by a very simple protocol. It was confirmed that addition
of the O,N,OAP ligand 4b, niobium(V) ethoxide and palladium or
rhodium complex in this order to the reaction solution at rt
resulted in quantitative formation of 11 and 12. Removal of free
ethanol in vacuo was not essential.
2.4. Heck reaction with the [ONOAP]Nb-Pd heterobimetallic complex
To adopt the preparative protocol of 11 for the catalytic reac-
tions, we chose Pd(dba)
2
as palladium(0) species. We added the
to benzen-d and examined the
ligand 4b, Nb(OEt) and Pd(dba)
5
2
6
3
1
reaction mixture. Similar change was observed in P NMR spectra
to the case of 11, although two signals were observed at 25 and 27
ppm. This clearly indicated that the phosphorus atom coordinated
to palladium metal. On the basis of these results, the formation of
complex 13 as a mixture of complexes that have one (13a) and two
Scheme 4. Preparation of O,N,OAP multidentate ligand 4. (i) PdCl
2
(dppf)ꢁCH
2 2
Cl 10
mol%, Na CO 4 eq, 75 °C, 24 h in THF/H O; (ii) 3 eq PhSiH , 120 °C, 36 h in xylene.
2
3
2
3
(
13b) coordinated ligands 10 can be suggested (Scheme 7).
1
Although the structure of 13 in solution is still vague, the
H
NMR spectrum of the reaction solution showed broad signals, sup-
porting the formation of the mixture and its equilibrium in solu-
tion. Our attempts to isolate 11 or 13 have been unsuccessful so
far, presumably because the ligand 4 includes chirality and dicoor-
dinated complex resulted in diasteromeric mixture and it makes
crystallization difficult.
Thus, we carried out Mizoroki-Heck reactions using the hetero-
bimetallic complexes 13 as catalyst. Acrylic acid and methyl acry-
late were used for coupling with iodobenzene. We envisioned that
acrylic acid might coordinate to niobium as acrylate by ligand
exchange with the ethoxide groups, which might facilitate coordi-
nation of the C@C moiety in acrylic acid to palladium to enhance
the catalytic ability in Mizoroki-Heck reaction (Fig. 4) [86].
The ELHB complex 13 was prepared in situ prior to the catalytic
reaction. The results are summarized in Table 1. The reaction of
acrylic acid and iodobenzene in the presence of 13 gave cinnamic
acid in 61% yield after stirring at 120 °C for 3 h (entry 1), while
Fig. 2. The molecular structure of 4b. Drawn with 50% probability. Hydrogen atoms
are omitted for clarity.
of 9 and 10. It have been reported that titanium-coordinated tri-
arylphosphines appears at 8–12 ppm in 31P NMR [83,84]. Possibil-
ity that the minor signal is due to the phosphine atom coordinated
to the metal cannot be ruled out, although it is unlikely. Mass spec-
trometry gave the molecular mass of the corresponding titanium
and niobium complexes.
5
the reaction without Nb(OEt) resulted in 44% (entry 2). Methyl
acrylate gave methyl cinnamate in 45% yield. The difference in
experimental results might suggest a cooperative effect by the
Nb-Pd heterobimetallic catalyst, although the effect was less sig-
nificant than expected.
Thus we examined another entry using an equimolar mixture of
acrylic acid and methyl acrylate, and it was reacted with iodoben-
zene in the presence of 13. However, cinnamic acid and methyl
cinnamate were obtained in 24% and 23% yield, respectively. This
result was contrary to expectations, and the study requires further
investigation.
2
.3. Preparation of Nb-Pd and Nb-Rh ELHB complexes of the [ONOAP]
ligand 4b
To accomplish the synthesis of early-late heterobimetallic com-
plexes the niobium complex 10 was employed for that purpose
because the niobium will not compete with late transition metal
for the coordination of the phosphine ligand. We added 0.5 equiv
3. Conclusion
2
of [Pd(p-allyl)Cl] to a benzene solution of 10 (Scheme 6). After
3
1
stirring at rt for 1 h, the P NMR spectroscopy showed that the
chemical shifts of the phosphine atom shifted downfield (26
ppm), indicating coordination of the phosphine to palladium
Multidentate O,N,OAP ligand was prepared from 2,6-lutidine
and its structure was unambiguously characterized. Using one of
these ligands, Nb-Pd and Nb-Rh heterobimetallic complexes were
selectively synthesized by a simple synthetic method. The Nb-Pd
complex catalyzed Mizoroki-Heck reaction, although the expected
synergetic effect was not clearly observed.
(
Fig. 3) [85]. This result suggested the formation of Nb-Pd hetero-
bimetallic complex 11. The rhodium complex, [RhCl(cod)] , was
stirred with 10 in benzene at rt for 1 h. Downfield shift of the phos-
2

3
58
N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
Scheme 5. Synthesis of titanium complexes using [ONOAP] ligands.
Scheme 6. Preparation of Nb-Pd complex 11 and Nb-Rh complex 12.

N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
359
Fig. 3. 31P NMR spectra of the ONOAP ligand 4b, mono- and heterobimetallic complexes, 10, 11 and 12.
Fig. 4. Potential ‘‘intramolecular” interaction of ligated acrylate and Pd in 13.
Scheme 7. Preparation of Nb–Pd complex 13 in situ.
ical Co., Inc. and degassed prior to use. Titanium(IV) isopropoxide,
niobium(V) ethoxide, 2,6-lutidine, 2,4-dimethylpentan-3-one, ben-
zophenone, n-butyllithium (1.6 M hexane solution), iron(III) chlo-
ride hexahydrate, were purchased from Kanto Chemical Co., Inc.
and used as received. 1,4-Dibromobenzene, 2-isopropoxy-4,4,5,5-
tetramethyl-1,3,2-dioxaborane, phenylsilane, cyclooctadiene rho-
dium(I) chloride dimer and allylpalladium(II) chloride dimer were
4
. Experimental section
4.1. General
All manipulations involving organometallic compounds were
conducted under argon using the standard Schlenk technique or
under nitrogen in a glove box. Anhydrous tetrahydrofuran was
purchased from Kanto Chemical Co., Inc. and purified with Glass
Contour Solvent System (SG Water, USA) prior to use. Hexane
and toluene (dehydrated grade) were purchased from Kanto Chem-
0
purchased from Tokyo Chemical Industry Co., Ltd. Dichloro[1,1 -bis
TM
(diphenylphosphino)ferrocene]palladium(II)
dichloromethane
adduct was purchased from Wako Pure Chemical Industries, Ltd.

3
60
N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
Table 1
CH), 2.93 (d, J = 14.9 Hz, 1H CH
), 2.94 (dd, J = 14.4, 9.3 Hz, 1H,
), 3.25 (dd, J = 2.7, 14.4 Hz, 1H,
), 5.43 (dd, J = 2.7, 9.3 Hz, 1H, CH(OH)), 7.00–7.15 (m, 3H, Ar-
2
Mizoroki-Heck Reactions using the Nb-Pd complex.
CH
CH
2
), 2.96 (d, J = 14.9 Hz, 1H, CH
2
2
13
1
H), 7.27–7.34 (m, 1H, Ar-H), 7.46–7.63 (m, 3H, Ar-H). C{ H}
NMR (CDCl , Me Si, 75.6 MHz): d 17.87, 18.00, 18.06, 35.00,
5.15, 39.03 (CH ), 44.80 (CH ), 72.50, 78.15 (q, CH(OH)), 121.27
3
4
3
2
2
(
(
Ar), 121.57 (q, Ar), 122.88 (Ar), 127.49 (Ar), 127.63 (Ar), 128.72
Ar), 132.51 (Ar), 137.38 (Ar), 142.70 (q, Ar), 157.56 (q, Ar),
1
60.67 (q, Ar).
4
.4. Synthesis of diphenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
Entry
R
X mol% of Nb
Yielda (%)
2-yl)phenyl)phosphine [87]
1
2
3
H
H
Me
4
0
4
61
44
45
To a solution of 1,4-dibromobenzene (3.54 g, 15 mmol) in THF
30 mL) was added dropwise n-butyllithium (1.6 M hexane solu-
(
a
Yields were determined by 1H NMR analysis of the crude product using tert-
tion, 9.2 mL, 15 mmol) at ꢀ78 °C, and the mixture was stirred for
1 h. Chlorodiphenylphosphine (3.23 g, 15 mmol) was added to this
solution and the mixture was stirred at ꢀ78 °C for 2 h. The mixture
was then warmed to rt and stirred for additional 1 h. After volatiles
were removed in vacuo, the residue was dissolved in THF (30 mL)
and cooled to ꢀ78 °C. n-Butyllithium (1.6 M hexane solution, 10.3
mL, 16.5 mmol) was added dropwise at this temperature and stir-
red at ꢀ78 °C for 1 h. To this mixture 2-isopropoxy-4,4,5,5-tetram-
ethyl-1,3,2-dioxaborane (3.63 g, 19.5 mmol) was added, and the
mixture was stirred for 0.5 h. And the reaction mixture was then
warmed to rt, and stirred for 2.5 h. To this mixture saturated
ammonium chloride aqueous solution (15 mL) was added, and
extracted with dichloromethane. The organic layer was washed
twice with water and brine, and dried over magnesium sulfate.
Volatiles were removed in vacuo and the residue was purified with
column chromatography (silica gel, hexane/EtOAc = 4/1) to give
butylbenzene as an internal standard.
2
-Bromobenzaldehyde, chlorodiphenylphosphine and bis(diben-
zylideneacetone)palladium(0) were purchased from Sigma-Aldrich
Co. LLC. Compounds 5a and 5b were prepared as previously
reported [52]. NMR spectra were recorded on JEOL ECX 300 and
ECA 500 spectrometers. The chemical shifts in 31P NMR spectra
were determined reference to triphenylphosphine (ꢀ6.0 ppm) as
an external standard. Fast atom bombardment (FAB) mass spec-
trometry was measured on JEOL JMS-700 instrument. EI-MS spec-
tra were recorded on a Shimadzu GCMS QP-5050. Electrospray
ionization-mass spectrometer (ESI-MS) spectra were recorded on
a JEOL JMS-T100LC instrument and are reported in mass-to-charge
ratio (m/z).
the title compound as colorless crystalline solid (4.78 g, 82%). 1
NMR (CDCl , Me Si, 300.5 MHz): d 1.33 (s, 12H, CH ), 7.24–7.33
m, 12H, Ar), 7.75 (dd, J = 1.7, 8.2 Hz, 2H, CH). P NMR (CDCl
H
3
4
3
4
.2. Synthesis of 2-(6-(2-(2-bromophenyl)-2-hydroxyethyl)pyridin-2-
yl)-1,1-diphenylethan-1-ol (6a)
3
1
(
3
,
PPh
3
for external standard = –6.0 ppm, 202.5 MHz): d ꢀ4.5.
To a solution of 5a (2.89 g, 10 mmol) in THF (20 mL) was added
n-butyllithium (1.6 M hexane solution, 20 mmol) dropwise at ꢀ78
4
2
.5. Synthesis of diphenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
-yl)phenyl)phosphine oxide (7) [88]
°
C. The mixture was warmed to ꢀ20 °C over a period of 5 h. The
orange mixture was again cooled to ꢀ78 °C, 2-bromobenzaldehyde
The reaction was carried out under an oxygen atmosphere (1
atm). To an acetonitrile (24 mL) solution of diphenyl(4-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)phosphine (4.78 g,
2 mmol) were added iron(III) chloride hexahydrate (324 mg, 1.2
(
2.22 g, 12 mmol) was added and stirred for 1 h. The pale orange
mixture was allowed to warm to rt and stirred for 2 h. Hydrochlo-
ric acid was then added to quench the reaction. The solution was
made basic by adding NaOHaq and extracted with dichloro-
methane. The organic layer was washed twice with water and
brine, and was dried over MgSO . Volatiles were removed in vacuo
4
and the residue was purified with column chromatography (silica
1
mmol) and potassium thiocyanate (350 mg, 3.6 mmol). The
bloody-red mixture was stirred at 80 °C for 22 h. After adding
aqueous sodium sulfite (10 mL) the reaction mixture was stirred
and extracted with dichloromethane. The organic layer was
washed twice with water and with brine, dried over magnesium
sulfate, and filtered. The filtrate was concentrated and purified
with column chromatography on silica gel (hexane/ethyl acetate
=
Me
7
gel, hexane/EtOAc = 4/1) to give 6a as white solid (2.70 g, 57%).
1
H NMR (CDCl
3
, Me
4
Si, 300.5 MHz): d 2.60 (br, 1H, OH), 2.84
), 3.22 (dd, J = 3.1, 14.4 Hz, 1H, CH ),
), 3.77 (d, J = 6 Hz, 1H, CH ), 5.31 (dd, J =
(
dd, J = 9.1, 14.4 Hz, 1H, CH
.76 (d, J = 6 Hz, 1H, CH
.1, 9.1 Hz, 1H, CH(OH)), 6.87 (d, J = 7.6 Hz, 1H, Py), 6.96 (d, J =
.9 Hz, 1H, Py), 7.07–7.29 (m, 8H, Ar), 7.37–7.51 (m, 7H, Ar).
2
2
3
3
7
2
2
1
1/4) to give 7 as white solid (4.61 g, 95% isol.). H NMR (CDCl
3
,
4 3
Si, 300.5 MHz): d 1.34 (s, 12H, CH ), 7.42–7.48 (m, 4H, Ar),
1
3
C
),
.51–7.57 (m, 2H, Ar), 7.62–7.72 (m, 6H, Ar), 7.89 (dd, J = 3.1, 8.3
1
{
3 4 2
H} NMR (CDCl , Me Si, 75.6 MHz): d 45.09 (CH ), 47.38 (CH
2
1
3
1
Hz, 2H, Ar). C{ H} NMR (CDCl
8
1
3 4
, Me Si, 125.8 MHz): d 24.87,
7
1
1
2.38, 78.44 (q), 121.47, 121.92 (q), 122.67, 126.05, 126.32,
26.51, 126.63, 127.33, 127.57, 127.97, 128.03, 128.70, 132.49,
37.37, 142.59 (q), 147.03 (q), 147.06 (q), 157.14 (q), 158.69 (q).
4.20, 128.50 (d, JPC = 12 Hz, 4C), 131.19 (d, JPC = 9.6 Hz, 2C),
31.96 (d, JPC = 2.4 Hz, 2C), 132.09 (d, JPC = 9.6 Hz, 4C), 134.55 (d,
JPC = 12 Hz, 2C), 135.13 (d, JPC = 102.6 Hz, q), a signal assignable
31
to C-B was not detected due to broadness and overlapping.
P
4.3. Synthesis of 3-((6-(2-(2-bromophenyl)-2-hydroxyethyl)pyridin-2-
3 3
NMR (CDCl , PPh for external standard = –6.0 ppm, 121.7 MHz):
yl)methyl)-2,4-dimethylpentan-3-ol (6b)
d 30.1.
The title compound was prepared similarly to 6a using 5b (2.21
g, 10 mmol) instead of 5a. Viscous yellow oil (3.70 g, 91%). H NMR
4.6. Preparation of 8a
1
(
=
3
CDCl
3
, Me
6.7 Hz, 3H, CH
H, CH ), 1.92 (sept, 6.9 Hz, 1H, CH), 1.94 (sept, J = 6.9 Hz, 1H,
4
Si, 300.5 MHz): d 0.89 (d, J = 6.8 Hz, 3H, CH
3
), 0.89 (d, J
The O,N,O-intermediate 6a (949 mg, 2 mmol) was dissolved in
THF (20 mL). To this solution the phosphine oxide 7 (1.21 g, 3
3
), 0.93 (d, J = 6.9 Hz, 3H, CH ), 0.94 (d, J = 6.7 Hz,
3
3
mmol), PdCl
2
(dppf)ꢁCH
2
Cl
2
(163 mg, 0.2 mmol) and aqueous

N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
361
1
sodium carbonate (0.4 M, 20 mL) were added in this order. The
vessel containing the deep crimson mixture was sealed and stirred
at 75 °C for 24 h. After being cooled to rt, the reaction mixture was
extracted with dichloromethane. The organic layer was washed
twice with water and once with brine, and dried over magnesium
sulfate. The solution was filtered, and the filtrate was concentrated.
Purification with column chromatography on acidic silica gel using
43%). H NMR (CDCl
3
, Me
4
Si, 300.5 MHz): d 0.82 (d, J = 6.9 Hz, 3H,
CH
(d, J = 6.9 Hz, 3H, CH
14.8 Hz, 1H, CH ), 2.87 (d, J = 14.8 Hz, 1H, CH
CH ), 5.22 (dd, J = 8.5, 4.1 Hz, 1H, CH), 6.68 (d, J = 7.2 Hz, 1H),
7.04 (d, J = 7.2 Hz, 1H), 7.20 (dd, J = 1.4 Hz, J = 7.6 Hz, 1H), 7.28–
3
), 0.85 (d, J = 6.9 Hz, 3H, CH
), 1.87 (sept, J = 6.9 Hz, 2H, CH), 2.85 (d, J =
), 2.97–3.03 (m, 2H,
3 3
), 0.88 (d, J = 6.9 Hz, 3H, CH ), 0.89
3
2
2
2
1
3
1
7.49 (m, 17H), 7.72 (d, J = 7.6 Hz, 1H). C{ H} NMR (CDCl
75.6 MHz): 17.89 (2C, CH ), 17.98 (CH ), 18.07 (CH ), 34.93, 35.15
(CH), 39.08 (CH ), 45.00 (CH ), 70.14 (C(OH)), 78.00 (q, C(OH)),
120.81, 122.73, 126.10, 127.26, 128.07, 128.52 (d, JPC = 7.2 Hz,
3 4
, Me Si,
ethyl acetate as an eluent gave the title compound as white solid
3
3
3
1
(
6
6
1.25 g, 93%). H NMR (CDCl
3
, Me
), 3.65 (dd, J = 15.5, 22.0 Hz, 2H, CH
.2 Hz, 1H, CH), 6.62 (d, J = 7.6 Hz, 1H, Py), 6.88 (d, J = 7.6 Hz, 1H,
4
Si, 300.5 MHz): d 2.91 (d, J =
2
2
3
.2 Hz, 2H, CH
2
2
), 5.10 (t, J =
3
4C), 128.76 (2C), 129.41 (d,
JPC = 7.2 Hz, 2C), 129.82 (CH), 132.09
13
1
(d, | JPC| = 10.1 Hz), 133.58 (d, 2JPC = 19.5 Hz, 2C), 133.75 (d, 2
1
Py), 7.07–7.76 (m, 25H, Ar). C{ H} NMR (CDCl
3
, Me
4
Si, 75.6
J
PC
=
1
MHz): d 45.39, 46.50, 68.64, 77.27, 120.70 (Ar), 121.58 (Ar),
19.5 Hz, 4C), 137.24 (d, | JPC| = 10.8 Hz, 2C, q), 137.28 (CH),
125.23, 125.53 (d, JPC = 11.3 Hz), 126.33, 126.95 (d, JPC = 5.9 Hz),
127.42, 127.48 (d, JPC = 12.5 Hz), 128.38 (d, JPC = 12.5 Hz), 128.73,
130.80, 130.91 (d, JPC = 2.8 Hz), 131.00, 131.05 (d, JPC = 5.9 Hz),
131.14, 131.18 (d, JPC = 2.3 Hz), 131.35 (d, JPC = 105 Hz), 131.49
139.81 (q), 140.94 (q), 141.38 (q), 157.83 (q), 160.62 (q). 31
NMR (CDCl , external standard = PPh
as ꢀ6.0 ppm, 121.7 MHz):
d ꢀ5.2. High resolution mass spectrometry (FAB+): [MꢀH] calcd.
for C39 P: 586.28749, found = 586.28839. The molecular
P
3
3
H41NO
2
(
1
d, JPC = 104 Hz), 143.70 (d, JPC = 2.5 Hz), 136.32, 138.06, 139.51,
structure of 4b was determined by X-ray diffraction study
(CCDC-1570197, see the Supporting Information).
31
46.01 (d, JPC = 11.7 Hz), 156.23, 157.55. P NMR (CDCl
3
, PPh
3
as
an external standard = –6.0 ppm, 121.7 MHz): d 29.7.
.7. Preparation of 8b
The title compound was prepared similarly to 8a using 6b (813
4
.10. Preparation of the titanium complex 9
4
The ligand 4b (59 mg, 0.1 mmol) was dissolved in benzene (0.6
mL) and to this solution titanium(IV) isopropoxide (29 mg, 0.1
mmol) was added. The mixture was stirred at rt for 1 h, the vola-
tiles were removed in vacuo leaving white solid. The formation
of the titanium complex 9 was observed by H NMR. P NMR
exhibited that 67% of the phosphorus atom did not coordinate to
1
mg, 2 mmol) instead of 6a. Brown solid (1.207 g, quant). H NMR
CDCl , Me Si, 300.5 MHz): d 0.78 (d, J = 7 Hz, 3H, CH ), 0.827 (d,
J = 7 Hz, 3H, CH ), 0.85 (d, J = 7 Hz, 3H, CH ), 0.86 (d, J = 7 Hz, 3H,
CH ), 1.80 (sept, J = 7 Hz, 1H, CH), 1.85 (sept, J = 7 Hz, 1H, CH),
,80 (d, J = 15 Hz, 1H, CH ), 2.82 (d, J = 15 Hz, 1H, CH ), 2.95 (dd,
J = 14.5, 3.8 Hz, 1H, CH ), 3.08 (dd, J = 14.5, 8.6 Hz, 1H, CH ), 5.16
dd, J = 8.6, 3.8 Hz, 1H, CH), 6.69 (d, J = 7.7 Hz, 1H, CH), 7.00 (d, J
(
3
4
3
1
31
3
3
3
1
2
2
2
the metal. H NMR (C
6
D
6
, Me
4
Si, 500 MHz): d 0.75 (d, J = 7 Hz,
), 1.14 (d, J = 7 Hz, 3H, CH ),
), 1.18 (d, J = 7 Hz, 3H, CH ), 1.26 (d, br, J
), 1.29 (d, J = 6 Hz, 3H, CH ), 1.31 (d, J = 6 Hz, 3H,
), 1.36 (d, J = 6 Hz, 3H, CH ),1.47 (d, J = 7 Hz, 3H, CH ), 1.49 (d,
J = 7 Hz, 3H, CH ), 1.84 (sept, J = 7 Hz, 1H, CH), 1.94 (sept, J = 7 Hz,
1H, CH), 2.76 (d, J = 14 Hz, 1H, CH ), 2.93 (dd, J = 14, 2 Hz, 1H,
CH ), 3.24 (dd, J = 14, 9 Hz, 1H, CH ), 3.27 (d, J = 14 Hz, 1H, CH ),
2
2
3H, CH
1.18 (d, J = 7 Hz, 3H, CH
= 7 Hz, 3H, CH
CH
3
), 0.86 (d, J = 7 Hz, 3H, CH
3
3
(
3
3
=
7.7 Hz, 1H, CH), 7.14 (d, J = 7.7 Hz, 1H, CH), 7.27–7.74 (m, 18H,
3
3
1
3
1
Ar). C{ H} NMR (CDCl
3 4
, Me Si, 75.6 MHz): d 17.74 (2C), 17.89,
3
3
3
1
1
1
6
1
7.95, 34.75, 34.98, 38.75, 45.99, 69.64, 77.82, 120.76, 122.46,
3
26.39, 127.13, 128.32 (J = 12 Hz, 4C), 128.35 (J = 12 Hz, 4C),
29.27, 129.44, 131.68, 131.76 (J = 3 Hz, 2C), 131.88 (J = 10 Hz,
C), 132.24 (J = 104 Hz, q, 1C), 132.28 (J = 104 Hz, q, 2C), 137.03,
2
2
2
2
4.52 (br, 1H, CH), 5.03 (sept, J = 6.3 Hz, 1H, CH), 5.18 (sept, J = 6.3
Hz, 1H, CH), 5.65 (dd, J = 9, 2 Hz, 1H, CH), 6.19 (d, J = 7.5 Hz, 1H,
Ar), 6.52 (d, J = 7.5 Hz, 1H, Ar), 6.84 (dd, J = 7.5, 7.5 Hz, 1H, Ar),
39.00, 140.88, 157.37, 160.34. 31P NMR (CDCl
3 3
, PPh as external
standard = ꢀ6.0 ppm, 121.7 MHz): d 29.6. High resolution mass
1
3
1
spectrometry (ESI+): [M + H] calcd. for C39
found = 604.29741.
3
H43NO P; 604.29805,
6.94–7.88 (m, 17H, Ar), 8.31 (d, J = 8 Hz, 1H, Ar). C{ H} NMR
(C , Me Si, 126.8 MHz) d 17.2, 17.3, 17.4, 17.6 (CH
ꢂ 4), 25.0,
5.1, 25.2, 25.3 (CH ꢂ 2), 40.9 (CH ), 46.1
ꢂ 4), 34.27, 34.30 (CH
(CH ), 75.6 (CH), 76.2 (CH), 76.3 (CH), 75.0 (br, CH), 85.6 (q),
120.2, 122.2, 125.4, 125.6, 126.9, 127.40 (d,
27.49, 128.42, 128.48, 128.52, 132.70 (d, 2JPC = 19 Hz), 132.8 (d,
6
D
6
4
3
2
3
3
2
0
0
4
2
.8. Preparation of 2-(6-(2-(4 -(diphenylphosphino)-[1,1 -biphenyl]-
2
3
-yl)-2-hydroxyethyl)pyridin-2-yl)-1,1-diphenylethanol (4a)
JPC = 6.6 Hz), 127.41,
1
2
In degassed xylene (20 mL), 8a (1.34 g, 2 mmol) and phenylsi-
J
PC = 19 Hz), 136.3 (aromatic CH ꢂ 14, two of 15 inequivalent car-
2
2
lane (649 mg, 6 mmol) were dissolved. The dark brown mixture
was sealed and stirred at 120 °C for 36 h. The reaction mixture
was then cooled to rt and concentrated in vacuo. The residue
was purified by column chromatography on FlorisilÒ (hexane/ethyl
acetate = 4/1). The title compound was obtained as colorless solid
bon atoms are overlapped), 134.9 (d, JPC = 12 Hz), 136.67 (d, JPC
=
2
12 Hz), 136.74 (d,
(aromatic quaternary carbon ꢂ 8). P NMR (C
dard = PPh
(FAB+; nitrobenzylalcohol as matrix): [Mꢀ(OC
calcd for C46 PTi; 785.3, found = 780.0.
JPC = 12 Hz), 138.1, 141.2, 142.4, 157.1, 158.2
3
1
6
D
6
, external stan-
3
as ꢀ6.0 ppm, 121.7 MHz): d ꢀ5.2. Mass spectrometry
3
H
7
)
2
+(OCH NO )]
2
6
C H
4
2
(
184 mg, 14%).
46 2 5
H N O
1
H NMR (CDCl
3
, Me
4
Si, 300.5 MHz): d 2.87 (dd, J = 14.0, 8.2 Hz,
), 3.63 (dd, J = 15.5,
), 5.14 (dd, J = 8.4, 4.2 Hz, 1H, CH), 6.56 (d, J =
.6 Hz, 1H, Py), 6.85 (d, J = 7.6 Hz, 1H, Py), 7.05–7.45 (m, 24H,
2
2
7
H, CH
2
), 2.90 (dd, J = 14.0, 4.0 Hz, 2H, CH
2
4.11. Preparation of the niobium complex 10
3.4 Hz, 2 H, CH
2
To a solution of the ligand 4b (59 mg, 0.1 mmol) in benzene
(0.6 mL) was added niobium(V) ethoxide (31 mg, 0.1 mmol) at rt.
The mixture was stirred at rt for 1 h, the volatiles were removed
in vacuo leaving white solid. The formation of the niobium com-
31
Ar), 7.54 (d, J = 7.6 Hz, 1H, Py). P NMR (CDCl
dard = PPh
obtained due to low solubility.
3
, external stan-
13
3
as ꢀ6.0 ppm, 121.7 MHz): d ꢀ5.7.
C NMR not
1
31
plex 10 was observed by H NMR. P NMR exhibited most of the
0
0
phosphorus atom (93%) did not coordinate to the metal. 1H NMR
4
2
.9. Preparation of 3-((6-(2-(4 -(diphenylphosphino)-[1,1 -biphenyl]-
-yl)-2-hydroxyethyl)pyridin-2-yl)methyl)-2,4-dimethylpentan-3-ol
(CDCl
= 7 Hz, 3H, CH
CH ), 1.29 (d, J = 7 Hz, 3H, CH
J = 7 Hz, 3H, CH ), 1.85 (sept, J = 7 Hz, 2H, CH), 2.14 (sept, J = 7 Hz,
2H, CH), 2.77 (d, J = 14 Hz, 2H, CH ), 3.91–4.11 (m, 4H, CH ),
3
, Me
4
Si, 300.5 MHz): d 0.81 (d, J = 7 Hz, 3H, CH
), 1.02 (d, J = 7 Hz, 3H, CH ), 1.13 (d, J = 7 Hz, 3H,
), 1.33 (t, J = 7 Hz, 3H, CH ), 1.43 (t,
3
), 0.98 (t, J
(4b)
3
3
3
3
3
The title compound was synthesized in a similar manner to 4a,
using 8b (1.21 g, 2 mmol) instead of 8a. Pale yellow solid (505 mg,
3
2
2

3
62
N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
4
1
=
.38–4.50 (m, 2H, CH
H, CH), 6.23 (d, J = 7 Hz, 1H, Ar), 6.56 (d, J = 7 Hz, 1H, Ar), 6.84 (t, J
2
), 4.79 (q, J = 7 Hz, 2H, CH
2
), 5.75 (d, J = 10 Hz,
dimer (25 mg, 0.05 mmol) was added to this yellow solution and
stirred at rt. Removal of the volatile in vacuo left the title com-
3
1
7.6 Hz, 1H, Ar), 7.04–7.41 (m, 16H, Ar), 8.51 (d, J = 7.6 Hz, 1H, Ar).
pound as yellow solid. The P NMR spectroscopy indicated at least
1
3
1
1
C{ H} NMR (CDCl
3
, Me
), 19.33 (CH
5.14 (CH), 36.71 (CH), 41.03 (CH
7.13 (CH O), 71.26 (CH
22.62, 124.69, 127.16, 127.67 (overlapped with C
4
Si, 75.6 MHz): d 18.35 (CH
3
), 18.89 (CH
3
),
),
93% of phosphorus atom coordinated to the metal. H NMR (CDCl
Me Si, 300.5 MHz): d 0.78 (d, J = 7.1 Hz, 3H, CH CH), 0.99 (t, J = 7.0
Hz, 3H, CH CH ), 1.01 (d, J = 7.0 Hz, 3H, CH CH), 1.13 (d, J = 7.0 Hz,
3H, CH CH), 1.27 (t, J = 7.0 Hz, 3H, CH CH ) 1.35 (d, J = 7.0 Hz, 3H,
CH CH), 1.47 (t, J = 7.0 Hz, 3H, CH CH ), 1.62 (m, 2H, cod), 1.75
(m, 2H, cod), 1.86 (sept, J = 7.1 Hz, 1H, CH), 2.14 (sept, J = 7.0 Hz,
1H, CH), 2.16 (m, 4H, cod), 2.73 (d, J = 14 Hz, 1H, CH ), 2.82 (d, J
= 13.6 Hz, 1H, CH ), 3.19 (br, 2H, cod), 3.81 (dd, J = 13.6, 10 Hz,
1H, CH ), 4.01 (dq, J = 10.7, 7.0 Hz, 1H, CH ), 4.09 (d, J = 14 Hz,
), 4.30 (dq, J = 10.7, 7.0 Hz, 1H, CH ), 4.41 (q, J = 7.0 Hz,
O), 4.82 (q, J = 7.0 Hz, 2H, CH O), 5.76 (d, J = 10 Hz, 1H,
3
,
1
3
6
1
9.07 (CH
3
3
3
), 19.37 (CH ), 19.48 (CH
3
), 19.69 (CH
3
4
3
2
), 46.46 (CH
2 2
), 66.48 (CH O),
3
2
3
2
2
O), 75.40 (CH-O), 85.00 (q, CAO),
), 128.39
), 128.77, 128.81 ( JPC = 9 Hz), 128.84,
3
3
2
6
D
6
3
3
2
3
(
overlapped with
C
6
D
6
3
3
2
1
1
=
1
28.98 ( JPC = 9 Hz), 129.83, 129.86 ( JPC = 10 Hz), 133.98 ( JPC
3 Hz), 134.03 ( JPC = 20 Hz), 134.25 ( JPC = 13 Hz), 136.46 (| JPC
13 Hz, q), 138.03 (| JPC| = 12 Hz, q), 138.06 (| JPC| = 13 Hz, q),
38.25 (CH), 139.67 (q), 142.66 (q), 143.85 (q), 160.56 (q), 161.26
=
|
2
2
2
1
2
1
1
2
2
1H, CH
2H, CH
2
2
3
1
(
1
q).
P
NMR (CDCl
21.7 MHz): d ꢀ5.1.
Mass spectrometry (FAB+, nitrobenzylalcohol as matrix):
ONOP-Nb( -OCH NO )] calcd. for C46 46NbN P; 830.2,
found = 830.0.
3
,
external standard = PPh
3
as ꢀ6.0 ppm,
2
2
CH), 5.89 (br, 2H, cod), 6.59 (d, J = 5.2 Hz, 1H), 6.62 (d, J = 5.4 Hz,
1H), 7.00–7.40 (m, 12H), 7.71 (m, 2H), 7.85 (m, 2H), 8.03 (dd, J =
10.1, 8.2 Hz, 2H), 8.55 (d, J = 7.8 Hz, 1H).
[
j
C
2 6
H
4
2
H
2 5
O
1
3
1
C{ H} NMR was not obtained due to low solubility. 31P NMR
(
CDCl
3
, external standard = PPh
3
as ꢀ6.0 ppm, 121.7 MHz): d
4.12. Preparation of the niobium-palladium complex 11
31.50 (d, JP-Rh = 157 Hz).
To a solution of the O,N,OAP ligand 4b (59 mg, 0.10 mmol) in
benzene (0.6 mL) was added Nb(OEt) (31 mg, 0.10 mmol) at rt.
4.14. Mizoroki-Heck reactions in the presence of 13
5
The mixture was stirred for 1 h at rt, and the volatiles were
removed in vacuo leaving 10 as white solid. The residue was dis-
solved in benzene (0.6 mL) and to this yellow solution was added
allylpalladium(II) chloride dimer (18 mg, 0.05 mmol) and stirred
at rt. Removal of the volatile in vacuo left the title compound as
Typical procedure for the catalytic Mizoroki-Heck reactions is as
follows. To a solution of 4b (24 mg, 0.04 mmol) in toluene (2 mL)
was added niobium(V) ethoxide (13 mg, 0.04 mmol) and the mix-
ture was stirred at rt for 0.5 h. And then bis(dibenzylideneace-
tone)palladium(0) (12 mg, 0.02 mmol) was added and the
mixture was stirred for 0.5 h to prepare 13 in situ. To this catalyst
solution was added iodobenzene (203 mg, 1 mmol), acrylic acid
(72 mg, 1 mmol) and triethylamine (202 mg, 2 mmol) and the ves-
sel was sealed and stirred at 120 °C for 3 h. Hydrochloric acid was
added to the dark brown mixture and extracted with dichloro-
methane. The organic layers were combined and the volatiles were
3
1
yellow solid. The P NMR spectroscopy indicated at least 91% of
1
phosphorus atom coordinated to the metal. H NMR (CDCl
00.5 MHz): d 0.80 (d, J = 7.2 Hz, 3H, CH ), 0.97 (t, J = 7.2 Hz, 3H,
CH ), 1.01 (d, J = 6.9 Hz, 3H, CH ), 1.13 (d, J = 6.9 Hz, 3H, CH
.29 (t, J = 6.9 Hz, 3H, CH ), 1.34 (d, J = 7.2 Hz, 3H, CH ) 1.46 (t, J
7.2 Hz, 3H, CH ), 1.86 (sept, J = 7.2 Hz, 1H, CH) 2.14 (sept, J =
.9 Hz, 1H, CH) 2.38 (d, J = 12.6 Hz, 1H, CH in allyl), 2.75 (d, J =
4.2 Hz, 1H, CH ), 2.82 (dd, J = 14.0, 1.0 Hz, 1H, CH ), 3.50 (br, 1H,
), 3.99 (dq, J = 10.7, 6.9
O), 4.07 (d, J = 14.2 Hz, 1H, CH ), 4.29 (dq, J = 10.7,
.9 Hz, 1H, CH O), 4.36–4.46 (m, 2H, CH O), 4.81 (q, J = 7.0 Hz,
H, CH O), 4.94 (m, 1H, allyl), 5.74 (dd, J = 10.0, 1.0 Hz, 1H, CH-
3 4
, Me Si,
3
3
3
3
3
)
1
=
6
1
3
3
3
1
2
removed in vacuo. The solid residue was measured by H NMR to
determine the yield of cinnamic acid using tert-butylbenzene as
internal standard (61%).
2
2
allyl), 3.88 (dd, J = 14.0, 10.0 Hz, 1H, CH
Hz, 1H, CH
2
2
2
6
2
2
2
Acknowledgments
2
O), 6.65 (d, J = 7.4 Hz, 2H), 7.03–7.40 (m, 18H), 8.54 (d, J = 7.9 Hz,
H), a few of allyl signals were overlapped with others. COSY did
This study was financially supported by JSPS KAKENHI (C)
7K05791. The authors thank Ms. E. Okano and Dr. K. Matsuura
for assistance in NMR measurement and mass spectrometry.
1
1
1
3
1
not show two-dimensional correlations of allyl protons. C{ H}
NMR (CDCl , Me Si, 75.6 MHz): d 18.30 (CH ), 18.90 (CH ), 19.02
), 19.32 (CH ), 19.34 (CH ), 19.44 (CH ), 19.59 (CH ), 35.07
CH), 36.60 (CH), 40.94 (CH ), 46.35 (CH ), 61.1 (CH , br, allyl),
6.31 (CH O), 67.09 (CH O), 71.13 (CH O), 75.49 (CH-O), 78.5
CH , br, allyl), 84.97 (q, CAO), 117.63 (d, JPC = 5.3 Hz, CH, allyl),
23.36 (CH), 124.78 (CH), 127.07 (CH), 127.64 (CH, overlapped
), 128.28 (CH), 129.47 (CH), 129.65 (d, J = 10.7 Hz, CH),
30.37 (J = 10.7 Hz, CH), 130.45 (J = 2.3 Hz, CH), 131.40 (J = 41.5
Hz, q), 132.26 (J = 10.0 Hz, CH), 133.36 (J = 40.9 Hz, q), 133.55 (J
3
4
3
3
(CH
3
3
3
3
3
Appendix A. Supplementary data
(
2
2
2
6
2
2
2
Supplementary data associated with this article can be found, in
the online version, at https://doi.org/10.1016/j.ica.2017.11.027.
(
2
1
6 6
with C D
1
References
[
1] For reviews, see Refs. [1–25]; V. Ritleng, M.J. Chetcuti, Chem. Rev. 107 (2007)
797–858.
2] B.G. Cooper, J.W. Napoline, C.M. Thomas, Catal. Rev. 54 (2012) 1–40.
=
1
1
40.7 Hz, q), 134.27 (J = 12.3 Hz, CH), 134.32 (J = 12.7 Hz, CH),
[
34.60 (J = 13.0 Hz, CH), 138.99 (q), 139.26 (CH), 143.97 (q),
44.43 (J = 20.1 Hz, q), 160.15 (q), 160.84 (q). 3 P NMR (CDCl
1
[3] N. Wheatley, P. Kalck, Chem. Rev. 99 (1999) 3379–3420.
4] Bifunctional Molecular Catalysis, Springer-Verlag: Berlin Heidelberg, 2011.
[5] B. Oelkers, M.V. Butovskii, R. Kempe, Chemistry 18 (2012) 13566–13579.
6] A. Inagaki, M. Akita, Coord. Chem. Rev. 254 (2010) 1220–1239.
7] A. Ceccon, S. Santi, L. Orian, A. Bisello, Coord. Chem. Rev. 248 (2004) 683–724.
8] S.K. Mandal, H.W. Roesky, Acc. Chem. Res. 43 (2010) 248–259.
9] M. Shibasaki, M. Kanai, S. Matsunaga, N. Kumagai, Acc. Chem. Res. 42 (2009)
1117–1127.
10] M. Westerhausen, Dalton Trans. (2006) 4755–4768.
11] K. Osakada, M. Tanabe, Bull. Chem. Soc. Jpn. 78 (2005) 1887–1898.
12] M. Akita, A. Sakurai, M.-C. Chung, Y. Moro-oka, J. Organomet. Chem. 670 (2003)
2–10.
13] A. Ricci, C. Lo Sterzo, J. Organomet. Chem. 653 (2002) 177–194.
14] M. Shibasaki, N. Yoshikawa, Chem. Rev. 102 (2002) 2187–2210.
15] C. Piguet, C. Edder, S. Rigault, G. Bernardinelli, J.-C.G. Bünzli, G. Hopfgartner, J.
Chem. Soc., Dalton Trans. (2000) 3999–4006.
3
,
[
external standard = PPh
resolution MS (FAB+): [M] calcd. for C48
3
as ꢀ6.0 ppm, 121.7 MHz): d 22.73. Low
[
[
[
[
5
H60ClNNbO PPd; 995.7,
found = 995.2.
4.13. Preparation of the niobium-rhodium complex 12
[
[
[
To a solution of the O,N,OAP ligand 4b (59 mg, 0.10 mmol) in
benzene (0.6 mL) was added Nb(OEt) (31 mg, 0.10 mmol) at rt.
5
[
[
[
The mixture was stirred for 1 h at rt, and the volatiles were
removed in vacuo leaving 10 as white solid. The residue was dis-
solved in benzene (0.6 mL). Chloro(1,5-cyclooctadiene)rhodium(I)

N. Suzuki et al. / Inorganica Chimica Acta 471 (2018) 355–363
363
[
[
[
[
16] M. Delferro, T.J. Marks, Chem. Rev. 111 (2011) 2450–2485.
17] N. Mankad, Synlett 25 (2014) 1197–1201.
18] B.J. Coe, Coord. Chem. Rev. 257 (2013) 1438–1458.
19] O. Wichmann, R. Sillanpää, A. Lehtonen, Coord. Chem. Rev. 256 (2012) 371–
[55] B. Koning, J. Buter, R. Hulst, R. Stroetinga, R.M. Kellogg, Eur. J. Org. Chem.
(2000) 2735–2743.
[56] J.J.H. Edema, R. Libbers, A. Ridder, R.M. Kellogg, A.L. Spek, J. Organomet. Chem.
464 (1994) 127–131.
3
92.
20] P.B. Chatterjee, K. Bhattacharya, M. Chaudhury, Coord. Chem. Rev. 255 (2011)
150–2164.
21] M. González-Maupoey, V. Tabernero, T. Cuenca, Coord. Chem. Rev. 253 (2009)
854–1881.
[57] B. Kaptein, G. Barf, R.M. Kellogg, F.V. Bolhuis, J. Org. Chem. 55 (1990) 1890–
1901.
[
[
2
[58] D.L. Goanvic, M. Holler, P. Pale, Tetrahedron Asymmetry 13 (2002) 119–121.
[59] C. Gómez, B. Maciá, M. Yus, ARKIVOC (2005) 10–20.
[60] H. Mack, M.S. Eisen, J. Chem. Soc., Dalton Trans. (1998) 917–921.
[61] J. Knizek, H. Nöth, Eur. J. Inorg. Chem. (2011) 1888–1900.
[62] M.C.W. Chan, K.-H. Tam, Y.-L. Pui, N. Zhu, J. Chem. Soc., Dalton Trans. (2002)
3085–3087.
1
[
[
[
[
[
22] A. Igashira-Kamiyama, T. Konno, Dalton Trans. 40 (2011) 7249–7263.
23] S. Szafert, L. John, P. Sobota, Dalton Trans. (2008) 6509–6520.
24] K. Severin, Chem.-A Eur. J. 8 (2002) 1514–1518.
25] R. Kempe, H. Noss, T. Irrgang, J. Organomet. Chem. 647 (2002) 12–20.
26] For examples, see also Refs. [9, 14 and 17]: C. Capacchione, A. Proto, J. Okuda, J.
Polym. Sci. Part A: Polym. Chem. 42 (2004) 2815–2822.
[63] R. Fandos, C. Hernández, A. Otero, A. Rodríguez, M.J. Ruiz, P. Terreros, Chem.-A
Eur. J. (2003) 671–677.
[64] For examples of niobium-containing heterobimetallic complexes, see Refs.
[64–80]; W.X. Oliveira, C.L. Pereira, C.B. Pinheiro, J. Cano, F. Lloret, M. Julve,
Chem. Commun. (Camb) 51 (2015) 11806–11809.
[65] D.A. Evers, A.H. Bluestein, B.M. Foxman, C.M. Thomas, Dalton Trans. 41 (2012)
8111–8115.
[66] R. Podgajny, D. Pinkowicz, T. Korzeniak, W. Nitek, M. Rams, B. Sieklucka, Inorg.
Chem. 46 (2007) 10416–10425.
[
[
[
[
27] S. Liu, A. Motta, A.R. Mouat, M. Delferro, T.J. Marks, J. Am. Chem. Soc. 136
(
2014) 10460–10469.
28] S. Liu, A. Motta, M. Delferro, T.J. Marks, J. Am. Chem. Soc. 135 (2013) 8830–
833.
29] G.J. Cheng, Y.F. Yang, P. Liu, P. Chen, T.Y. Sun, G. Li, X. Zhang, K.N. Houk, J.Q. Yu,
Y.D. Wu, J. Am. Chem. Soc. 136 (2014) 894–897.
8
30] L. Wan, N. Dastbaravardeh, G. Li, J.Q. Yu, J. Am. Chem. Soc. 135 (2013) 18056–
[67] D.J. Mindiola, K. Meyer, J.-P.F. Cherry, T.A. Baker, C.C. Cummins,
Organometallics 19 (2000) 1622–1624.
1
8059.
[
[
[
31] R.Y. Tang, G. Li, J.Q. Yu, Nature 507 (2014) 215–220.
[68] O. Lavastre, G. Bonnet, G. Boni, M.M. Kubicki, C. Moïse, J. Organomet. Chem.
547 (1997) 141–147.
[69] P. Oudet, G. Bonnet, C. Moise, Polyhedron 14 (1995) 2173–2177.
[70] G.I. Nikonov, D.A. Lemenovskii, L.G. Kuzmina, J. Organomet. Chem. 496 (1995)
187–190.
[71] A. Antiñolo, F. Carrillo, M. Fajardo, S. Garcia-Yuste, A. Otero, J. Organomet.
Chem. 482 (1994) 93–98.
[72] P. Oudet, M.M. Kubicki, C. Moise, Organometallics 13 (1994) 4278–4284.
[73] F. Calderazzo, G.E. De Benedetto, G. Pampaloni, L. Rocchi, U. Englert, J.
Organomet. Chem. 462 (1993) C10–C11.
32] D. Leow, G. Li, T.S. Mei, J.-Q. Yu, Nature 486 (2012) 518–522.
33] T. Mizuta, C. Miyaji, T. Katayama, J.-I. Ushio, K. Kubo, K. Miyoshi,
Organometallics 28 (2009) 539–546.
[
[
[
34] C. Takayama, Y. Yamaguchi, T. Mise, N. Suzuki, J. Chem. Soc., Dalton Trans.
(
2001) 948–953.
35] Y. Yamaguchi, N. Suzuki, T. Mise, Y. Wakatsuki, Organometallics 18 (1999)
96–1001.
36] H. Ishino, S. Takemoto, K. Hirata, Y. Kanaizuka, M. Hidai, M. Nabika, Y. Seki, T.
Miyatake, N. Suzuki, Organometallics 23 (2004) 4544–4546.
9
[
[
[
[
[
[
[
37] I.G. Powers, C. Uyeda, ACS Catal. 7 (2016) 936–958.
[74] P.M. Boorman, J.F. Fait, G.K.W. Freeman, Polyhedron 8 (1989) 1762–1764.
[75] M.Y. Darensbourg, R. Silva, J. Reibenspies, C.K. Prout, Organometallics 8 (1989)
1315–1323.
[76] K.S. Wong, W.R. Scheidt, J.A. Labinger, Inorg. Chem. 18 (1979) 1709–1712.
[77] K.S. Wong, W.R. Scheidt, J.A. Labinger, Inorg. Chem. 18 (1979) 136–140.
[78] B. Balbach, S. Baral, H. Biersack, W.A. Herrmann, J.A. Labinger, W.R. Scheidt, F.J.
Timmers, M.L. Ziegler, Organometallics 7 (1988) 325–331.
[79] D. Perrey, J.C. Leblanc, C. Moïse, J. Martin-Gil, J. Organomet. Chem. 412 (1991)
363–370.
[80] Y.V. Skripkin, A.A. Pasynskii, V.T. Kalinnikov, M.A. Porai-Koshits, L.K.
Minacheva, A.S. Antsyshkina, V.N. Ostrikova, J. Organomet. Chem. 231 (1982)
205–217.
[81] H. Ishii, M. Goyal, M. Ueda, K. Takeuchi, M. Asai, Appl. Catal. A 201 (2000) 101–
105.
38] P. Buchwalter, J. Rose, P. Braunstein, Chem. Rev. 115 (2015) 28–126.
39] J.F. Berry, C.M. Thomas, Dalton Trans. 46 (2017) 5472–5473.
40] S. Ishikawa, K. Manabe, Angew. Chem. Int. Ed. Engl. 49 (2010) 772–775.
41] M. Yamaguchi, K. Manabe, Org. Lett. 16 (2014) 2386–2389.
42] K. Ohmatsu, N. Imagawa, T. Ooi, Nat. Chem. 6 (2014) 47–51.
43] A.J. Martinez-Martinez, A.R. Kennedy, R.E. Mulvey, C.T. O’Hara, Science 346
(
2014) 834–837.
[
[
44] Y. Kuninobu, H. Ida, M. Nishi, M. Kanai, Nat. Chem. 7 (2015) 712–717.
45] G. Chen, W. Gong, Z. Zhuang, M.S. Andra, Y.Q. Chen, X. Hong, Y.F. Yang, T. Liu, K.
N. Houk, J.-Q. Yu, Science 353 (2016) 1023–1027.
[
[
46] F.L. Zhang, K. Hong, T.J. Li, H. Park, J.-Q. Yu, Science 351 (2016) 252–256.
47] J. He, S. Li, Y. Deng, H. Fu, B.N. Laforteza, J.E. Spangler, A. Homs, J.-Q. Yu, Science
3
43 (2014) 1216–1220.
[
48] D.H. Wang, K.M. Engle, B.F. Shi, J.-Q. Yu, Science 327 (2010) 315–319.
[82] See the Supporting Information.
[
49] K.S. Chan, M. Wasa, L. Chu, B.N. Laforteza, M. Miura, J.-Q. Yu, Nat. Chem. 6
[83] K.-W. Chou, W.-J. Su, H.-F. Huang, X.-R. Zou, Y.-N. Chang, P.-Y. Lee, L.-C. Liang,
Polyhedron 125 (2017) 164–172.
[84] R.J. Long, V.C. Gibson, A.J. White, D.J. Williams, Inorg. Chem. 45 (2006) 511–
513.
[85] S. Fantasia, S.P. Nolan, Chem.-A Eur. J. 14 (2008) 6987–6993.
[86] We observed the mixture of 13 and acrylic acid by 1H NMR to examine
potential interaction between acrylate and Pd. However, the results were
unsatisfactory to support our idea. See the Supporting Information for the
detail.
[87] E. Lee, J. Lim, Y. Kim, J. Park, E. Jeong, S. Hwang, in: L. Samsung Display Co. (Ed.),
US, 2015.
[88] M. Zhu, Y. Li, J. Miao, B. Jiang, C. Yang, H. Wu, J. Qin, Y. Cao, Org. Electron. 15
(2014) 1598–1606.
(
2014) 146–150.
50] Y.J. Liu, H. Xu, W.J. Kong, M. Shang, H.X. Dai, J.-Q. Yu, Nature 515 (2014) 389–
93.
51] X.C. Wang, W. Gong, L.Z. Fang, R.Y. Zhu, S. Li, K.M. Engle, J.-Q. Yu, Nature 519
2015) 334–338.
52] N. Suzuki, K. Haraga, T. Shimamura, Y. Masuyama, Eur. J. Inorg. Chem. 2015
2015) 5480–5487.
53] N. Suzuki, G. Kobayashi, T. Hasegawa, Y. Masuyama, J. Organomet. Chem. 717
2012) 23–28.
[
[
[
[
[
3
(
(
(
54] For examples of ONO ligands, see Refs. [54–63]; G. Vargas, N. Farfán, R.
Santillan, A. Gutiérrez, E. Gómez, V. Barba, Inorg. Chim. Acta 358 (2005) 2996–
3
002.