Gold(I) Complexation of Phosphanoxy-Substituted Phosphaalkenes for Activation-Free LAuCl Catalysis

Article abstract of DOI:10.1002/chem.202004281

The phosphanoxy-substituted phosphaalkene bearing the P=C?O?P skeleton can be prepared from diphosphene Mes*P=PMes* (Mes=2,4,6-tBu₃C₆H₂), and their use for catalysis is of interest. In this paper, complexation of the phosp

Full text of DOI:10.1002/chem.202004281

Accepted Article
Accepted Article
Title: Gold(I) Complexation of the Phosphanoxy-Substituted
Phosphaalkenes for the Activation-Free LAuCl Catalysis
Authors: Miki Kato, Yasuhiro Ueta, and Shigekazu Ito
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.202004281
Link to VoR: https://doi.org/10.1002/chem.202004281
0
1/2020

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
Gold(I) Complexation of the Phosphanoxy-Substituted
Phosphaalkenes for the Activation-Free LAuCl Catalysis
Miki Kato, Yasuhiro Ueta, and Shigekazu Ito*[a]
Dedication ((optional))
[
a]
M. Kato, Dr. Y. Ueta, Prof. Dr. S. Ito
Department of Applied Chemistry, School of Materials and Chemical Technology
Tokyo Institute of Technology
2-12-1-H113 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)
E-mail: ito.s.ao@m.titech.ac.jp
Homepage: http://www.apc.titech.ac.jp/~sito/index-e.html
Supporting information for this article is given via a link at the end of the document.((Please delete this text if not appropriate))
Abstract: The phosphanoxy-substituted phosphaalkene bearing the
P=C–O–P skeleton can be prepared from diphosphene
enough to cause the following molecular transformations.[10]
However, several phosphaalkene-chlorogold(I) complexes can
catalyze molecular transformations without activation using silver
co-catalyst.[5a,7,11] It is plausible that the strong π-accepting
character of P=C can promote the Lewis acid functionality on the
3 6 2
Mes*P=PMes* (Mes* = 2,4,6-tBu C H ), and the use for catalysis is of
interest. In this paper, complexation of the phosphanoxy-substituted
phosphaalkenes with gold are investigated, and the catalytic activity
of the mono- and bis(chlorogold) complexes are subsequently
evaluated. Reaction of the P=C–O–P compound with (tht)AuCl (tht =
–
gold centre(s) even in the presence of Cl ion. In addition, most of
the phosphaalkene-chlorogold(I) catalysts can be recovered after
the reactions, which is promising to develop sustainable chemical
processes.[12]
3
tetrahydrothiophene) showed dominant coordination on the sp
2
phosphorus, and complete coordination on the sp phosphorus
required removal of tetrahydrothiophene. Atoms-In-Molecules (AIM)
analysis based on the X-ray structure of the mono(chlorogold)
complex indicated pseudo coordinating interaction between the gold
centre and the P=C unit. The bis(chlorogold) complexes indicated the
The first isolable diphosphene Mes*P=PMes* (Mes* = 2,4,6-
tBu C H , supermesityl) is one of the key compounds for recent
3 6 2
progress on the chemistry of multiple bonds including heavier
main group elements.[13] The “true phosphobenzene” has been
utilized as a starting materials for synthesis of low-coordinated
phosphorus compounds by cleaving the P=P double bond.[
Previously, we described a metathesis-type transformation of
Mes*P=PMes* by using an organolithium reagent and an acyl
chloride affording phosphanoxy-substituted phosphaalkene 1 via
the P–P bond cleavage in the acyl-substituted diphosphane
intermediates (Scheme 1).[14] The presence of both sp and sp3
phosphorus atoms in 1 is quite attractive as one of the non-
symmetric P2 ligand system. Whereas attempted synthesis of
conformational
isomerism,
and
catalyzed
3,4b]
cycloisomerization/alkoxyclization of 1,6-enyne and for hydration of
terminal alkyne without the activation treatment. Even the
mono(chlorogold) complexes catalyzed the alkoxycyclization
reactions without silver co-catalyst, indicating that the alcohols were
effective in activating the AuCl unit.
2
Introduction
chelate transition-metal complexes bearing
1
has been
unsuccessful until now, use of 1 for chemistry of gold complexes
has been possible.
Phosphaalkenes bearing P=C double bond(s) have been utilized
as strong π-accepting ligands because of the low-lying LUMO
levels comparable with that of carbon monoxide (CO). Although
the phosphorus-carbon multiple bonds are normally too reactive
to isolate, the kinetic stabilization method using sterically
encumbered substituents enables to protect the heavier
unsaturated bonds from reactive species.[1,2] So far, many kinds
of isolable low-coordinated organophosphorus compounds have
R2
R2
O
P–P
cleavage Mes*
1
1
) R Li
P
Mes*
P
O
P
P
Mes*
Mes*
P
2
Mes*
P
R1
R1
Mes*
2) R C(O)Cl
1
been reported,[3,4] and several transition-metal-based Lewis acid
Scheme 1. P=P bond cleavage of diphosphene Mes*P=PMes* affording
phosphanoxy-substituted phosphaalkene 1.
catalysts have been developed.[5,6]
We have utilized kinetically stabilized phosphaalkenes for
[7]
developing homogeneous gold catalysis. Homogeneous gold
catalysis featuring the soft π-acidic character has greatly been
progressed over the past few decades, and many catalytic
molecular transformations have been established.[8,9] In general,
the catalytically active gold complexes bearing the ligated
phosphines should not contain chloride, because Cl– ion binds
with gold strongly and prevent coordination of the substrates
In this paper, we describe preparation and catalytic activity of
chlorogold(I) complexes bearing 1. Although the P=C unit in 1
basically shows inferior coordination ability to AuCl, the sp2
phosphorus atom is effective to increase catalytic activity of the
gold centre even in the presence of chloride ion. In the course of
structure determination, the bis(chlorogold) complexes indicated
1
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
dynamic conformational changes. Interestingly, weak interaction
between the P=C group and the sp3 phosphanoxy-coordinated
gold centre in the mono(chlorogold) complex might be effective to
catalyze the cyclization process under the activation-free
conditions accompanying alcohols.
effective to increase the Lewis acidity on the gold centre. The
[15,16]
Atoms-in-Molecule (AIM) study
showed the trajectory from
2
the sp phosphorus atom and the gold centre, indicating both a
pseudo -donation from the lone pair and a back-donating π-
coordination to the P=C unit (Figure 1b).[ Thus, the presence of
P=C–O skeleton in 2a might increase the Lewis acidity by
weakening the Au–Cl interaction. The NBO analysis could not
give scalable parameters depicting the small interaction between
17]
Results and Discussion
2
the gold centre and the sp -phosphorus atom.
Preparation and structure of chlorogold complex bearing the
ligated P=C–O–P system
According to our previous report,[14] phosphanoxy-substituted
a)
phosphaalkenes
1
were prepared from diphosphene
Mes*P=PMes*, organolithium reagents, and benzoyl chloride.
Reaction of 1 with 1 eq of (tht)AuCl (tht = tetrahydrothiophene)
allowed predominant coordination of the gold on the sp3
phosphorus in the phosphanoxy group, and the corresponding
mono(chlorogold) complexes 2 were isolated in moderate yields
(
(
Scheme 2, Eq 1). On the other hand, reaction of 1 with 2 eq of
tht)AuCl was sluggish and gave mixtures of bis(chlorogold)
complexes 3 together with 2. This result indicates that, in contrast
to most of phosphaalkenes we have investigated so far,[7]
coordination ability of the P=C unit in 1 is considerably weak
probably due to the presence of the oxo unit, and comparable with
that of tetrahydrothiophene. To avoid cumbersome purification
processes in the synthesis of 3, the volatile materials including
tetrahydrothiophene were removed from the reaction mixture of 1
and 2 eq of (tht)AuCl, and subsequent addition of the solvent
b)
(
dichloromethane) was conducted. This procedure was
successful, and only bis(chlorogold) complexes 3 were isolated in
good yields (Scheme 2, Eq 2). It should be mentioned that de-
coordination of AuCl from the sp2 phosphorus generating gold
nanoparticles was somewhat problematic in the preparation and
isolation of 3b.
Figure 1. a) An ORTEP drawing of 2a of 50% probability level. Hydrogen atoms
are omitted for clarity. One of the o-CMe groups in the P1-connected Mes* unit
3
is disordered, and the atoms of the predominant occupancy factor (0.68) are
shown. Bond lengths (Å) and angles (°): Au–Cl 2.296(3), P1–Au 2.232(2), O–
Ph
Ph
P1 1.633(5), O–C1 1.431(8), C1–P2 1.698(8), P1–Au–Cl 176.5(1), P1–O–C1
Mes*
(tht)AuCl (1 eq)
CH Cl , RT, 5 h
Mes*
2
1
23.5(4). b) A 2D contour plot of the Laplacian distribution ∇ (r) in 2a in the
P
O
P
O
(1)
R
2
2
R
plane of P1, P2, and Au. The bond critical points (BCPs) are colored light green.
The AIM analysis was conducted based on the single point calculation at the
P
P
Mes*
ClAu Mes*
2

B97XD/SDD(Au), 6-31+G(d). At the BCP between the sp phosphorus atom
1
1
a: R = nBu
b: R = Ph
2a (65%)
2b (64%)
and the gold centre (blue arrow), (r) and ∇ (r) of 0.0144 e Bohr and +0.0332
2
–3
–5
e Bohr are characterized, respectively.
1) (tht)AuCl (2 eq)
Ph
CH Cl , RT, 1 h
Mes*
Although the solution quality was not acceptable due to the lack
of X-ray diffraction data enough to determine the metric
parameters completely, the X-ray structure of 3a (R = nBu)
revealed two conformers without obvious Au–Au contact, and
intramolecular Au···Au distances of 5.563 and 5.663 Å were
observed in the crystalline state (Figure 2). The P=C–O–P
2
2
P
O
P
(2)
1
2
3
) in vacuo
AuCl
ClAu
R
) CH Cl , RT, 1 h
2
2
Mes*
3a (80%)
b (85%)
3
skeleton
in
1
is
comparable
with
dppe
[1,4-
Scheme 2. Synthesis of chlorogold(I) complexes bearing the phosphanoxy-
substituted phosphaalkenes.
bis(diphenylphosphino)ethane] that provides bis(chlorogold)
complex avoiding the intramolecular aurophilic interaction.[
18]
Figure 1a shows an ORTEP drawing of 2a indicating that the P=C
moiety directs to the gold centre with the P···Au distance of 3.404
Å. The P2–C1 distance is almost the same as that of 1 (1.701
Å).[14] The structure of 2a indicates the pseudo chelate interaction,
which would relate with the lower coordination ability of 2 (vide
supra). The Au–Cl distance of 2.296 Å is slightly elongated
compared with 3 (vide infra), indicating that the P=C unit might be
2
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
Figure 3. a) A 31P{ H} NMR spectrum of 3b (121 MHz, 300K, C
filling drawing of the DFT-simulated structure of 3b at the B97XD/SDD(Au), 6-
1G(d) level.
1
6
6
D ). b) A space-
3
Catalytic activity of bis(chlorogold) complexes bearing the
ligated P=C–O–P system
As we have demonstrated so far, phosphaalkene-chlorogold(I)
complexes can catalyze several molecular transformations by
activating the terminal alkyne units without silver co-catalyst.[
Bis(chlorogold) complexes 3 can also be used for several catalytic
reactions without Ag salt. Tables 1 and 2 display hydration of 2-
propynyl acetate and cycloisomerization of 1,6-enyene catalyzed
by 3, respectively. Both 3a and 3b showed comparable catalytic
activity with the mononuclear chlorogold complex bearing
7a-f]
Mes*P=CPh
2
.[7a] Complexes 3 showed no decomposition in the
hydration and cycloisomerization reactions.
Figure 2. A drawing of the qualitatively determined structures of 3a in the
crystalline state. Hydrogen atoms are omitted for clarity. Bond lengths around
the gold centres (Å): P1–Au 2.226(4), P2–Au2 2.238(3), Au1–Cl1 2.264(6),
Au2–Cl2 2.285(3), P3–Au3 2.230(4), P4–Au4 2.234(3), Au3–Cl3 2.270(6), Au4–
Cl4 2.278(3).
Table 1. Gold-catalyzed hydration of 2-propynyl acetate.
In the NMR analyses of 3b (R = Ph), the broadened 31P NMR (121
MHz) signals were observed around  140 and 180 at 300 K
Au cat. (3 mol%)
H O (10 eq)
2
OAc
O
OAc
Ph
Ph
acetone, RT, 48 h
(
Figure 3a), which is in sharp contrast with 3a (
P
138.7, 154.0;
3
PP = 40.4 Hz). The 31P NMR spectrum of 3b might correlate with
J
the rapid interconversion between at least two conformers.
Neither separation nor sharpening of the 31P NMR signals was
observed between 183–323 K. Preliminary DFT calculations for
Yield (%)[a]
Recovery (%)[b]
Au cat.
3a
69
60
31
40
3
b as well as the X-ray structure of 3a indicated that the aurophilic
3b
interaction[
19]
might not be advantageous. Therefore, we
speculated that the presence of four aromatic rings in 3b might
produce the propeller-type conformations (Figure 3b). In the H
1
[
a] Determined by H NMR.
1
8
VT-NMR analyses (400 MHz, THF-d ), the aromatic protons
showed coalesce around 243 K, and the protons of the Ph-C=P
unit became non-equivalent below 213 K ( ~ 360 Hz, see
Supporting Information). According to the Gutowky-Holm’s
formula,[20] activation energy (G ) of 11 kcal/mol was roughly
estimated.
Table 2. Gold-catalyzed cycloisomerization of 1,6-enyne.
‡
MeO C
Au cat. (3 mol%)
CH Cl , RT, 24 h
MeO2C
MeO2C
2
MeO C
2
2
2
Au cat.
Yield (%)[a]
Recovery (%)[b]
3
a
b
95
93
0
7
3
1
[
a] Determined by H NMR.
Table 3 summarizes alkoxycyclization of 1,6-enyne catalyzed by
. Whereas 3a showed a moderate catalytic activity, 3b gave the
3
methylenecyclopentene product in an excellent yield. However,
both 3a and 3b showed de-coordination of AuCl from the P=C unit
in the catalytic process, and the mononuclear complexes 2 were
obtained after the alkoxycyclization reaction. Although the
2
detailed mechanism has been unclear, the sensitive P(sp )-Au
bond to alcohol might correlate with the lower coordination ability
of the sp2 phosphorus in 1. Considerable amount of the de-
coordination product 2b after the catalytic reaction using 3b
3
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
correlated with the instability observed during the preparation
process.
6
was not facilitated by 2b even in the presence of AgSbF (see
Supporting Information).
Table 3. Gold-catalyzed alkoxycyclization of 1,6-enyne.
Table 5. Alkoxycyclization of 1,6-enyne catalyzed by mononuclear complexes
2.
MeO C
3 (3 mol%)
MeO2C
MeO2C
2
MeO C
Au cat. (3 mol%)
MeO2C
2
CH Cl / MeOH (1:1)
MeO C
2
2
2
RT, 24 h
MeO C
CH2Cl2 / MeOH (1:1)
RT, Time
MeO C
2
2
OMe
OMe
3
Yield (%)[a]
Recovery of 1,6-
enyne (%)[
Recovery of 3
(%)
Yield of
(%)
2
a]
[b]
[b]
Yield (%)[a]
Entry
Au cat.
Time (d)
Recovery of 1,6-
enyne (%)[
a]
3
a
b
73
97
23
3
84
67
16
33
1
2
3
4
5
6
7
2a
1
1
6
6
1
3
1
19
15
62
95
25
80
0
81
85
38
<5
75
20
>99
3
2b
2a
a] Determined by H NMR. [b] Determined by 31P NMR.
1
[
2b
2b[b]
2b[b]
4
The superior catalytic activity of 3b for the allkoxycyclization
prompted to examine other catalytic reaction including
hydroalkoxylation. As shown in Table 4, 2,2-diphenylhexa-4,5-
dien-1-ol was converted into the corresponding 2-
vinyltetrahydrofuran in a low yield (Entry 1). Use of AgSbF
co-catalyst improved the yield up to 91% (Entry 2).
6
as a
1
[
a] Determined by H NMR. [b] Reaction was carried out at 40 °C.
OEt
Table 4. Gold-catalyzed intramolecular hydroalkoxylation of allenyl alcohol.
Ph P
2
AuCl
O
4
Ph Ph
3
b (5 mol%)
OH
•
As discussed above, the presence of P=C–O skeleton in 2a might
increase the Lewis acidity by interacting over the gold centre. Also,
possible H-bond interaction between the chloride in 2 and
methanol might be advantageous to the activation-free catalytic
alkoxycyclization. Although the detailed analysis should be
conducted, Figure 4 suggests a plausible interaction that increase
the Lewis-acid character on the gold centre in 2.[22,23] In the
alkoxycyclization reaction with 3, methanol might facilitate de-
Toluene, RT, 24 h
Ph
Ph
Entry
Additive
Yield (%)[a]
Recovery (%)[a]
1
2
–
11
91
89
9
AgSbF
6
(10 mol%)
2
coordination of AuCl from the sp phosphorus atom (see Table 3).
The 31P NMR titration study showed that the amount of methanol
1
[
a] Determined by H NMR.
affected the 31P chemical shifts and the spin-spin coupling
parameters, although the deviation was considerably small (see
Supporting Information).
Mono(chlorogold) complexes (2) for the activation-free gold
catalysis
In addition to bis(chlorogold) complexes 3, catalytic reactions
using the mononuclear complexes 2 were also examined. The
hydration and the cycloisomerization reactions did not occur in the
presence of 2. On the other hand, alkoxycyclization of 1,6-enyne
was catalyzed in the presence of 2 (Table 5). Both 2a and 2b
provided small amounts of the cyclization product after 24 h (Entry
Ph
Mes*
P
O
P
R
Au
Mes*
1
, 2). Elongation of the reaction time was effective to improve the
yield up to 62% with 2a (Entry 3) and, to our delight, 95% with 2b
Entry 4). No decomposition of 2 was observed after the catalytic
Cl
(
H OMe
processes. Warming at 40 °C was effective to accelerate the
reaction (Entry 5, 6). The methoxydiphenylphosphine-
chlorogold(I) complex 4 showed no catalytic activity, indicating
that the presence of the P=C unit in 2 is responsible to the gold-
catalyzed the alkoxycyclization under the activation-free condition
Figure 4. Plausible interaction between 2 and methanol increasing the Lewis
acidity of the gold centre.
[
21]
To explore the effects of alcohol on the catalytic activity of the
mono(chlorogold) complex in more detail, reaction of 1,6-enyne
(
Entry 7). The intramolecular hydroalkoxylation of allenyl alcohol
4
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
7.1 Hz), 7.31–7.35 (m, 4H); 13C{ H} NMR (75 MHz, CDCl
J = 15.9 Hz), 25.9, 31.0, 31.4, 32.9 (d, J = 6.7 Hz), 33.0 (d, J = 6.8 Hz),
4.6, 35.0, 37.1 (d, J = 33.3 Hz), 40.0–41.0, 122.5 (d, J = 8.4 Hz), 124.7
d, J = 1.8 Hz), 126.8 (d, J = 6.3 Hz), 127.2 (d, J = 2.0 Hz), 128.0 (d, J =
.4 Hz), 131.0 (dd, J = 61.7 Hz, J = 3.8 Hz), 138.7 (d, J = 3.3 Hz), 138.9
d, J = 3.5 Hz), 151.3, 151.9 (d, J = 3.3 Hz), 155.3 (d, J = 2.1 Hz), 155.7
1
in the presence of other alcohols was investigated. Whereas
tBuOH deactivated the catalytic functionality of 2b, use of 2,2,2-
3
)  14.1, 23.4 (d,
3
(
3
(
(
trifluoroethan-1-ol (CF
cycloisomerization process (Scheme 3). Although the low
nucleophilicity of CF CH OH was useless for the alkoxylation
3 2
CH OH) was quite effective to promote the
3
2
process, the increased Lewis acid character by the perfluorinated
ethanol was suitable to activate the alkyne unit leading to the
vinylcyclopentene product.
d, J = 1.5 Hz), 187.9 (dd, J = 44.0 Hz, J = 8.8 Hz); 31P{ H} NMR (121 MHz,
CDCl )  123.9 (d, J = 93.0 Hz), 198.7 (d, J = 93.0 Hz); HRMS (APCI) calcd
1
3
+
2
for C47H72AuClNaOP [M+Na] 969.4310, found 969.4312.
X-ray crystallographic data of 2a: C47
dimensions = 0.230 x 0.200 x 0.080 mm , orthorhombic, Pna2
H
72ClOP
2
Au, M
W
= 947.40, crystal
(#33), a =
MeO C
2b (3 mol%)
MeO2C
MeO2C
2
3
1
CH Cl /CF CH OH (1:1)
20.3117(4), b = 22.7508(8), c = 10.2382(7) Å, V = 4731.1(4) Å , Z = 4, T =
23 K,  = 0.71075 Å, calc = 1.330 g m–3, µMoK = 3.265 mm–1, F000 = 1952,
3
MeO C
2
2
3
2
2
RT, 24 h
1
96%
–26≤h≤26, –29≤k≤28, –12≤l≤13, 45194 total reflections (2max = 54.97°),
10327 unique (Rint = 0.0369), R = 0.0383 (>2(I)), 0.0441 (all data), wR2
= 0.1146 (>2(I)), 0.1201 (all data), S = 0.952 (482 parameters). CCDC-
2025940.
Scheme 3. Cycloisomerization of 1,6-enyne promoted by 2b in the presence of
,2,2-trifluroethan-1-ol.
2
Preparation of 2b: A mixture of 1b (73.5 mg, 0.10 mmol) and (tht)AuCl
(32.1 mg, 0.10 mmol) in dichloromethane (1 mL) was stirred for 5 h at the
room temperature. After the volatile materials are removed in vacuo, the
Conclusion
resultant residue was washed with hexane (5 ml) to afford 2b as a white
In conclusion, we described utility of the phosphaoxy-substituted
phosphaalkenes for the activation-free gold catalysis. The
mononuclear structure of 2 accompanied weak interaction
between the P=C unit and the gold centre, which might increase
the Lewis acidity. Bis(chlorogold) complexes 3 did not contain the
aurophilic interaction, and showed the conformational isomerism
probably due to the presence of four aryl substituents.
Bis(chlorogold) complexes 3 containing the P(sp )–Au bond
catalyzed cyclioisomerization/alkoxycyclization of 1,6-enyne and
hydration of 2-propynyl acetate without the activation treatment.
1
solid (62.2 mg, 64%). H NMR (300 MHz, CDCl
3
)  0.82 (s, 9H), 1.02 (s,
9
2
7
3
H), 1.26 (s, 9H), 1.36 (s, 9H), 1.40 (s, 9H), 1.62 (s, 9H), 6.05–6.09 (m,
H), 6.65–6.71 (m., 2H), 6.88 (t, 1H, J = 2.9 Hz), 7.05–7.08 (m, 2H), 7.20–
.30 (m, 3H), 7.32–7.41 (m, 4H); 13C{ H} NMR (75 MHz, CDCl
1
3
)  31.1,
1.4, 32.2 (d, J = 6.0 Hz), 32.9 (d, J = 6.7 Hz), 33.6 (d, J = 2.9 Hz), 33.9,
34.7, 34.9, 37.2, 38.1, 39.8, 41.4, 123.1 (d, J = 11.2 Hz), 123.7 (d, J = 7.7
Hz), 126.3 (d, J = 4.2 Hz), 126.7 (d, J = 1.7 Hz), 126.8 (d, J = 6.3 Hz),
127.5 (d, J = 3.1 Hz), 127.9–128.3, 131.0 (dd, J = 62.3 Hz, J = 5.9 Hz),
2
132.5 (d, J = 2.1 Hz), 137.2 (d, J = 60.6 Hz), 138.9 (dd, J = 17.3 Hz, J =
4
.5 Hz), 151.1, 152.1 (d, J = 2.6 Hz), 154.6, 156.0 (d, J = 3.7 Hz), 158.9
1
(
(
(
d, J = 8.0 Hz), 160.7 (d, J = 3.8 Hz), 186.9 (d, J = 13.7 Hz); 31P{ H} NMR
Interestingly, even mono(chlorogold) complexes
2 showed
121 MHz, CDCl
APCI) calcd for C49
3
)  107.6 (d, J = 124.4 Hz), 188.9 (d, J = 124.4 Hz); HRMS
catalytic activity in the alkoxycyclization, indicating the additional
effects of alcohol for increase of the Lewis acidity. The findings of
this study suggest novel design for the sustainable gold catalysis
as well as for elucidation of catalytic mechanisms promoted by
the phosphaalkene unit.
+
H
68AuClNaOP
2
[M+Na] 989.3997, found 989.3976.
Preparation of 3a: A mixture of 1a (71.5 mg, 0.10 mmol) and (tht)AuCl
64.1 mg, 0.20 mmol) in dichloromethane (1 mL) was stirred for 1 hour at
(
the room temperature. After the volatile materials are removed under the
reduced pressure, the resultant residue was dissolved in dichloromethane
(1 mL) under nitrogen atmosphere. The mixture was stirred for 1 h at the
room temperature, and the volatile materials were removed under the
Experimental Section
reduced pressure. The resultant residue was washed with hexane (5 ml)
1
to afford 3a as a pink solid (98.2 mg, 80%). H NMR (300 MHz, CDCl
3
) 
All experiments were carried out under inert atmosphere (nitrogen or
argon) unless otherwise noted. H NMR, 13C NMR, and 31P NMR spectra
were measured on a Bruker AVANCE 300 spectrometer or a JEOL JNM-
ECZ400S (400 MHz) spectrometer. Chemical shifts of 1H NMR were
0
1
1
.85–0.91 (m, 1H), 1.03 (t, 3H, J = 7.3 Hz), 1.31 (s, 18H), 1.37 (s, 9H),
.54 (s, 9H), 1.68 (s, 9H), 1.83 (s, 9H), 1.83–2.00 (m, 2H), 2.10–2.30 (m,
H), 2.73–2.85 (m, 1H), 3.55–3.69 (m, 1H),5.79–5.83 (m, 2H), 6.67 (pt, 2H,
1
J = 7.2 Hz), 6.99–7.06 (m, 1H), 7.29–7.31 (m, 2H), 7.53–7.58 (m, 2H);
expressed in parts per million downfield from CHCl
standard ( = 7.26) in CDCl , C as an internal standard ( = 7.16) in
. Chemical shifts of C NMR were expressed in parts per million
downfield from CDCl as an internal standard ( = 77.16) in CDCl , C
as an internal standard ( = 128.4). Chemical shifts of 31P NMR were
expressed in parts per million downfield from 85% H PO as an external
3
as an internal
13
1
C{ H} NMR (75 MHz, CDCl )  14.1, 23.8 (d, J = 21.1 Hz), 31.1, 32.3 (d,
3
3
6 6
H
J = 5.6 Hz), 33.9, 34.2, 34.3 (d, J = 1.7 Hz), 34.7, 35.4, 38.2 (d, J = 25.6
Hz), 38.9 (d, J = 2.0 Hz), 39.0 (d, J = 2.1 Hz), 40.5 (d, J = 3.9 Hz), 118.7
13
6 6
C D
3
3
6 6
D
(
=
d, J = 32.3 Hz), 123.1 (d, J = 10.1 Hz), 123.9 (d, J = 7.7 Hz), 124.5 (d, J
36.3 Hz), 125.3 (d, J = 9.5 Hz), 125.9 (d, J = 9.3 Hz), 127.1 (d, J = 10.1
Hz), 128.0 (d, J = 3.7 Hz), 130.7 (d, J = 5.8 Hz), 136.1 (d, J = 4.4 Hz),
3
4
standard ( = 0). Mass spectra were measured on a JEOL JMS-T100LC
spectrometer. X-ray diffraction data were measured on a Rigaku RAXIS-
RAPID diffractometer. The structures were solved by a direct method
1
1
53.1 (d, J = 4.5 Hz), 155.6 (d, J = 3.0 Hz), 157.4, 158.2 (d, J = 3.3 Hz),
58.6, 159.6 (d, J = 18.3 Hz), 183.5 (dd, J = 103.2 Hz, J = 6.1 Hz); 31P{1H}
NMR (121 MHz, CDCl
HRMS (APCI) calcd for C47
3
)  138.7 (d, J = 40.4 Hz), 154.0 (d, J = 40.4 Hz);
(
SHELXL-2014).[24] The X-ray structure solution and refinement were
carried out using the Yadokari-XG software.[25] Density Functional Theory
DFT) calculations were carried out using Gaussian 09 (B.01) package.[26]
+
2
H72Au Cl
2
NaOP
2
[M+Na] 1201.3664, found
1201.3654.
(
2 2 W
X-ray crystallographic data of 3a: C47H72Cl OP Au2 M = 1179.81, crystal
dimensions = 0.160 x 0.160 x 0.080 mm , triclinic, P-1 (#2), a = 15.9562(5),
Preparation of 2a: A mixture of 1a (71.5 mg, 0.10 mmol) and (tht)AuCl
32.1 mg, 0.10 mmol) in dichloromethane (1 mL) was stirred for 5 h at the
room temperature. After the volatile materials are removed in vacuo, the
3
(
b = 18.3089(6), c = 20.0597(8) Å,  = 116.9745(9),  = 98.5272(10),  =
3
1
1
2
01.1501(5) °, V = 4934.0(3) Å , Z = 4, T = 143 K,  = 0.71075 Å, calc
=
resultant residue was washed with hexane (5 ml) to afford 2a as a pink
–3
–1
.588 g m , µMoK = 6.145 mm , F000 = 2336, –20≤h≤20, –23≤k≤23, –
6≤l≤25, 79631 total reflections (2max = 54.97°), 22476 unique (Rint
1
solid (61.1 mg, 65%). H NMR (300 MHz, CDCl
3
)  0.57 (t, 3H, J = 6.7 Hz),
=
0.85–1.20 (m, 5H), 1.33 (s, 18H), 1.46 (s, 18H), 1.50 (s, 18H), 2.30–2.50
(
m, 1H), 6.22 (d, 2H, J = 7.9 Hz), 6.77 (pt, 2H, J = 7.8 Hz), 6.95 (t, 1H, J =
5
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
0
0
.0634), R = 0.0583 (>2(I)), 0.1073 (all data), wR2 = 0.1477 (>2(I)),
.2350 (all data), S = 1.436 (898 parameters). See Supporting Information.
[2]
MesP=CPh
2
: T. C. Klebach, R. Lourens, F. Bickelhaupt, J. Am. Chem.
Soc. 1978, 100, 4886–4888.
[
[
[
3]
4]
5]
a) K. B. Dillon, F. Mathey, J. F. Nixon, Phosphorus: The Carbon Copy
Wiley, Chichester, 1999; b) M. Regitz, O. J. Scherer Eds., Multiple Bonds
and Low Coordination in Phosphorus Chemistry Thieme, Stuttgart, 1990.
a) F. Mathey, Angew. Chem. Int. Ed. 2003, 42, 1578–1604; Angew.
Chem. 2003, 115, 1616–1643; b) M. Yoshifuji, J. Chem. Soc. Dalton
Trans. 1998, 3343–3350.
Preparation of 3b: A mixture of 1a (73.5 mg, 0.10 mmol) and (tht)AuCl
64.1 mg, 0.20 mmol) in dichloromethane (1 mL) was stirred for 1 h at the
room temperature. After the volatile materials are removed under the
reduced pressure, the resultant residue was dissolved in dichloromethane
(
(1 mL) under nitrogen atmosphere. The mixture was stirred for 1 h at the
a) F. Ozawa, M. Yoshifuji, Dalton Trans. 2006, 4987–4995; b) P. Le Floch,
Coord. Chem. Rev. 2006, 250, 627–681; c) J. Dugal-Tessier, E. D.
Conrad, G. R. Dake, D. P. Gates, “Phosphaalkenes” in Phosphorus(III)
Ligands in Homogeneous Catalysis (Eds.: P. C. J. Kamer, P. W. N. M.
van Leeuwen), Wiley, Chichester, 2012, pp 321–341.
room temperature, and the volatile materials were removed under the
reduced pressure. The resultant residue was washed with hexane (5 ml)
to afford 3b as a pink solid (102.1 mg, 85%). 13C{ H} NMR (75 MHz, CDCl
1
3
)

31.0, 31.0, 33.8 (d, J = 3.5 Hz), 34.3, 34.5, 34.8, 35.1, 38.9 (d, J = 1.4
Hz), 39.9, 41.3, 122.8 (d, J = 10.4 Hz), 123.5, 124.8, 126.5–128.5, 129.4,
33.3, 135.0 (dd, J = 54.8 Hz, J = 0.7 Hz), 135.4–136.5, 153.1 (d, J = 3.0
Hz), 154.6 (d, J = 2.8 Hz), 157.5 (d, J = 1.4 Hz), 158.1, 159.3–159.7, 161.4,
[
6]
a) M. Okazaki, H. Hayashi, D.-F. Fu, S.-T. Liu, F. Ozawa,
Organometallics 2009, 28, 902–908; b) J. Waluk, H.-P. Klein, A. J. Ashe,
J. Michl, Organometallics 1989, 8, 2804–2808.
1
1
90.6 (d, J = 47.3 Hz); HRMS (APCI) calcd for C49
2
H68Au Cl
2
NaOP
2
+
[7]
a) S. Ito, T. Shinozaki, K. Mikami, Eur. J. Org. Chem. 2017, 6889–6900;
b) S. Ito, M. Nanko, T. Shinozaki, M. Kojima, K. Aikawa, K. Mikami, Chem.
Asian J. 2016, 11, 823–827; c) S. Ito, M. Nanko, K. Mikami,
ChemCatChem 2014, 10, 1032–1036; d) S. Ito, L. Zhai, K. Mikami, Chem.
Asian J. 2011, 6, 3077–3083; e) S. Ito, S. Kusano, N. Morita, K. Mikami,
M. Yoshifuji, J. Organomet. Chem. 2010, 695, 291–296; f) M. Freytag, S.
Ito, M. Yoshifuji, Chem. Asian J. 2006, 1, 693–700; g) S. Ito, M. Freytag,
M. Yoshifuji, Dalton Trans. 2006, 710–713.
[M+Na] 1221.3351, found 1221.3307.
Hydration of propargyl acetate[27]: To a corresponding chlorogold complex
(
(
3 mol%), a solution of propargyl acetate (17.4 mg, 0.10 mmol) in acetone
1 mL) and H O (1.0 mmol) was added at the room temperature. After
2
stirred for 48 hours, the reaction mixture was directly loaded on a silica gel
SiO ) column and eluted with hexane/ethyl acetate 6:1 to give 2-oxo-1-
phenylpropyl acetate as a colorless oil.
(
2
[8]
Selected books: a) A. S. K. Hashmi, F. D. Toste (Eds.), Modern Gold
Catalyzed Synthesis Wiley-VCH, Weinheim, 2012; b) F. D. Toste, V.
Michelet (Eds.), Gold Catalysis: A Homogeneous Approach Imperial
College Press, 2014; c) L. M. Slaughter (Eds), Top. Curr. Chem. 2015,
Cycloisomerization of 1,6-enyne[28]
: To a corresponding chlorogold
complex (3 mol%), a solution of 1,6-enyne (25.3 mg, 0.10 mmol) in
dichloromethane (1 mL) was added at the room temperature. After stirred
for 24 h, the reaction mixture was directly loaded on a silica gel column
and eluted with hexane/ethyl acetate 6:1 to give the cycloisomerization
product as a colorless oil.
3
57, 1–284. d) A. M. Echavarren, M. E. Muratore, V.López-Carrillo, A.
Escribano-Cuesta, N. Huguet, C. Obradors, Org. React. 2017, 92, 1–
11; e) E. Merino, A. Salvador, C. Nevado, Science of Synthesis,
4
Applications of Domino Transformations in Organic Synthesis (S. A.
Snyder Ed.) 2016, 1, 535–575.
Alkoxycyclization of 1,6-enyne[28]: To a corresponding chlorogold complex
[9]
Recent reviews on gold catalysis: a) T. A. C. A. Bayrakdar, T. Scattolin,
X. Ma, S. P. Nolan, Chem. Soc. Rev. 2020, 49, 7044–7100; b) L.
(
(
3 mol%), a solution of 1,6-enyne (25.3 mg, 0.10 mmol) in dichloromethane
0.5 mL) and methanol (0.5 mL) was added at the room temperature. After
Rocchigiani,
0.1021/acs.chemrev.0c00552; c) L.-W. Ye, X.-Q. Zhu, R. L. Sahani, Y.
Xu, P.-C. Qian, R.-S. Liu, Chem. Rev. DOI:
0.1021/acs.chemrev.0c00348; d) P. Milcendeau, N. Sabat, A. Ferry, X.
M.
Bochmann,
Chem.
Rev.
DOI:
stirred for 24 h, the reaction mixture was directly loaded on a silica gel
column and eluted with hexane/ethyl acetate 6:1 to give the product as a
colorless oil.
1
1
Guinchard, Org. Biomol. Chem. 2020, 17, 6006–6017; e) S. Banerjee, V.
W. Bhoyare, N. T. Patil, Chem. Commun. 2020, 56, 2677–2690; f) A.
Nijamudheen, A. Datta, Chem. Eur. J. 2020, 26, 1442–1487; g) V.
Pirovano, G. Abbiati, E. Brambilla, E. Rossi, Eur. J. Inorg. Chem. 2020,
962–977; h) B. Huang, F. D. Toste, Trends Chem. 2020, 2, 707–720; i)
G. Meera, K. R. Rohit, G. S. S. Treesa, G. Anilkumar, Asian J. Org. Chem.
2020, 9, 144–161; j) G. Zuccarello, M. Zanini, A. M. Echavarren, Isr. J.
Chem. 2020, 60, 360–372; k) X.-T. Tang, F. Yang, T.-T. Zhang, Y.-F. Liu,
T.-F. Su, D.-C. Lv, W.-B. Shen, Catalysts 2020, 10, 350; l) X. Zhao, M.
Rudolph, A. S. K. Hashmi, Chem. Commun. 2019, 55, 12127–12135; m)
R. Murakami, F. Inagaki, Tetrahedron Lett. 2019, 60, 151231; n) C.
Praveen, Coord. Chem. Rev. 2019, 392, 1–34; o) E. Aguilar, J.
Santamaria, Org. Chem. Front. 2019, 6, 1513–1540; p) F. Gagosz,
Synthesis 2019, 51, 1087–1099; q) J. L. Mascareñas, I. Varela, F. López,
Acc. Chem. Res. 2019, 52, 465–479; r) M. Brill, S. P. Nolan, Top.
Organomet. Chem. 2018, 62, 51–90; s) M. O. Akram, S. Banerjee, S. S.
Saswade, V. Bedi, N. T. Patil, Chem. Commun. 2018, 54, 11069–11083;
t) W. Fang, M. Shi, Chem. Eur. J. 2018, 24, 9998–10005; u) A. Fürstner,
Angew. Chem. Int. Ed. 2018, 57, 4215–4233; Angew. Chem. 2018, 130,
Intramolecular hydroalkoxylation of allenyl alcohol[29]: A mixture of 3b (5
mol%) and additive in toluene (0.4 mL) was stirred for 10 min at room
temperature. To the mixture in toluene was added 2,2-diphenylhexa-4,5-
dien-1-ol (25.3 mg, 0.10 mmol) in toluene (0.6 mL) at room temperature.
After stirring for 24 h, the reaction mixture was directly loaded on a short
silica gel column and eluted with hexane/ethyl acetate to give the 2-
vinyltetrahydrofuran as a colorless oil.
Acknowledgements
This work was supported in part by Grants-in-Aid for Scientific
Research (No. 19H02685) from the Ministry of Education, Culture,
Sports, Science and Technology, and Nissan Chemicals Co. Ltd.
The authors thank Prof. Tetsuro Murahashi and Dr. Koji
Yamamoto of Tokyo Institute of Technology for supporting the VT-
NMR experiments. Prof. Toshiro Takao of Tokyo Institute of
Technology supported the X-ray diffraction measurements. The
authors thank the referees for suggesting intensive studies for
elucidating the effects of alcohol on mono(chlorogold) complexes
4289–4308.
[10] A. Zhdanko, M. E. Maier, ACS Catal. 2014, 4, 2770–2775.
[11] Catalytic properties of phosphinine-AuCl complexes: M. a) Rigo, E. R. M.
Habraken, K. Bhattachayya, M. Weber, A. W. Ehlers, N. Mezáilles, J. C.
Slootweg, C. Müller, Chem. Eur. J. 2019, 25, 8769–8779; b) M. Rigo, L.
Hettmanczyk, F. J. L. Heutz, S. Hohloch, M. Lutz, B. Sarkar, C. Müller,
Dalton Trans. 2017, 46, 86–95.
2
as well as exploration of unprecedented catalytic processes.
Keywords: phosphaalkenes • gold catalysis • conformational
isomerism • electron density distribution • coordination chemistry
[
12] a) B. Wagner, K. Belger, S. Minkler, V. Belting, N. Krause, Pure Appl.
Chem. 2016, 88, 391–399; b) A. Collado, A. Gomez-Suarez, S. P. Nolan,
RSC Green Chemistry Series 2016, 39, 41–90.
[1]
R. C. Fischer, P. P. Power, Chem. Rev. 2010, 110, 3877–3923.
6
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
[
[
[
[
[
[
[
13] M. Yoshifuji, I. Shima, N. Inamoto, K. Hirotsu, T. Higughi, J. Am. Chem.
Soc. 1981, 103, 4587–4589; 1982, 104, 6167.
14] S. Ito, S. Okabe, Y. Ueta, K. Mikami, Chem. Commun. 2014, 50, 9204–
9206.
15] a) R. F. W. Badar, Atoms in Molecules – A Quantum Theory Oxford
University Press, Oxford, 1990.
16] M. Rigoulet, S. Massou, E. D. S. Carrizo, S. Mallet-Ladeira, A. Amgoune,
K. Miqueu, D. Bourissou, PNAS 2019, 116, 46–51.
17] G. Zuccarello, M. Zanini, A. M. Echavarren, Isr. J. Chem. 2020, 60, 360–
3
72.
18] D. S. Eggleston, D. F. Chodosh, G. R. Girard, D. T. Hill, Inorg. Chim. Acta
985, 108, 221–226.
19] H. Schmidbaur, W. Graf, G. Müller, Angew. Chem. Int. Ed. Engl. 1988,
7, 417–419; Angew. Chem. 1988, 100, 439–441.
1
2
[
20] H. S. Gutowsky, C. H. Holm, J. Chem. Phys. 1956, 25, 1228–1234.
21] a) Y. Yang, V. Ramamoorthy, P. R. Shart, Inorg. Chem. 1993, 32, 1946–
[
1950; b) D. A. Couch, S. D. Robinson, J. N. Wingfield, J. Chem. Soc.
Dalton Trans. 1974, 1309–1313.
[22] R. Ebule, S. Liang, G. B. Hammond, B. Xu, ACS Catal. 2017, 10, 6798–
6801.
[
[
[
23] S. Sen, F. P. Gabbaï, Chem. Commun. 2017, 53, 13356–13358.
24] G. Sheldrick, T.Schneider, Acta Cryst. C 2015, 71, 3.
25] Yadokari-XG, Software for Crystal Structure Analyses, K. Wakita (2001);
Release of Software (Yadokari-XG 2009) for Crystal Structure Analyses,
C. Kabuto, S. Akine, T. Nemoto, E. Kwon, J. Cryst. Soc. Jpn. 2009, 51,
218–224.
[
26] a) M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb,
J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson,
H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino,
G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T.
Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J.
J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R.
Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S.
Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox,
J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W.
Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P.
Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, Revision
B.01, Gaussian, Inc., Wallingford CT, 2010; b) B97XD: J.-D. Chai, M.
Head-Gordon, Phys. Chem. Chem. Phys. 2008, 10, 6615–6620.
27] N. Ghosh, S. Nayak, A. Sahoo, J. Org. Chem. 2011, 76, 500–511.
28] C. Nieto-Oberhuber, M. P. Muñoz, S. López, E. Jiménez-Núñez, C.
Nevado, E. Herrero-Gómez, M. Raducan, A. M. Echavarren, Chem. Eur.
J. 2006, 12, 1677–1693.
[
[
[29] Z. Zhang, C. Liu, R. E. Kinder, X. Han, R. A. Widenhoefer, J. Am. Chem.
Soc. 2006, 128, 9066–9073.
7
This article is protected by copyright. All rights reserved.

Chemistry - A European Journal
10.1002/chem.202004281
FULL PAPER
Entry for the Table of Contents
Insert graphic for Table of Contents here. ((Please ensure your graphic is in one of following formats))
Ph
Ph
Mes*
Mes*
P
O
P
O
Au = AuCl
Au
Mes*
Catalytically Active
Sensitive
R
Interacting
P
P
Mes* = 2,4,6-tBu C H
6 2
3
Au R
Mes*
Au
The phosphanoxy-substituted phosphaalkens are employed for developing the chemistry of LAuCl complexes. The bis(chlorogold)
2
complexes indicated the conformational isomerism, and the relatively sensitive P(sp )–Au bonding was effective for the activation-
free gold catalysis. Even the mono(chlorogold) complexes including the Au···P=C pseudo coordination interaction enabled the
activation-free reactions including alcohols.
Institute and/or researcher Twitter usernames: ((optional))
8
This article is protected by copyright. All rights reserved.