A Phosphonium Ylide as a Ligand for [3 + 2] Coupling Reactions of Epoxides with Heterocumulenes under Mild Conditions

Article abstract of DOI:10.1021/acs.joc.0c01101

The potential of carbonyl-stabilized phosphonium ylides as ligands for novel catalysis was explored. We found that the combination of phosphonium ylides and metal halide salts efficiently catalyzed the reaction of epoxides with carbon dioxide under mild c

Full text of DOI:10.1021/acs.joc.0c01101

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Note
A Phosphonium Ylide as a Ligand for [3+2] Coupling Reactions
of Epoxides with Heterocumulenes under Mild Conditions
Yasunori Toda, Kousuke Hashimoto, Yoko Mori, and Hiroyuki Suga
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.0c01101 • Publication Date (Web): 27 Jul 2020
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The Journal of Organic Chemistry
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A Phosphonium Ylide as a Ligand for [3+2] Coupling Reactions of
Epoxides with Heterocumulenes under Mild Conditions
Yasunori Toda,* Kousuke Hashimoto, Yoko Mori, Hiroyuki Suga*
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ABSTRACT: The potential of carbonyl-stabilized phosphonium ylides as ligands for novel catalysis was explored. We found that the
combination of phosphonium ylides and metal halide salts efficiently catalyzed the reaction of epoxides with carbon dioxide
under mild conditions. 5-Membered cyclic carbonates, including disubstituted cyclic carbonates, were obtained in good yields
with the use of 1 atm of carbon dioxide at 35 °C. Terminal epoxides could be converted to N-aryl oxazolidinones in the reaction
with isocyanates under a similar catalytic system.
KEYWORDS: phosphonium ylide, bifunctional catalyst, carbon dioxide, epoxide, cyclic carbonate
Phosphonium ylides have gained long-overdue attention
from chemists due to their impressive ability as carbanions.
The main contributions to this chemistry concern the Wittig
reaction,1 but the use of phosphonium ylides as ligands for
metals also remains an attractive area of research.2 Intriguing
aspects of ylide ligands are ascribed to their several bonding
modes, in that the nature of the substituents on the carbon
atom allows a negative charge to be delocalized through
auxiliary functional groups including carbonyl groups (Figure
1a, resonance forms I-IV).3 Regarding carbonyl group-
stabilized phosphonium ylides that exhibit an ambidentate
character (C- vs. O-coordination), the C-coordination mode is
more common.4 Recently, Zhou et al. reported [3+2] coupling
reactions of terminal epoxides with 1 atm of carbon dioxide
(CO2) by bifunctional catalysis (Figure 1b, R2 = R3 = H).5a
Phosphonium ylides coordinate with the cobalt-salen
complex to release iodide ion. The generated anion, in turn,
can be positioned proximal to the phosphonium cation, which
serves as a nucleophile towards epoxides under the influence
of the Lewis acidic cobalt complex. They found that the cis O-
coordination mode predominated while the ylide itself
existed as a cis/trans mixture. It was hence deduced that a
conformation-restricted cis-ylide may be more effective for
activating metal halide complexes. Meanwhile, we developed
Lewis acid catalysis based on the combination of ylide ligands
L and metal halides, namely, the ylide-M-X system.
The synthesis of industrially important chemicals by the
environmentally-friendly CO2 fixation has been one of the
goals for creating a sustainable society, due to the merit of
CO2 as a C1 source.8 In particular, Lewis acid catalysis with an
external nucleophilic halide ion for the CO2 capture to
produce five-membered cyclic carbonates has been
extensively studied to date.9 The progress of carbonate
synthesis by homogeneous catalysis over the past decade
achieved mild conditions of atmospheric CO2 pressure and a
temperature lower than 40 °C mostly except for disubstituted
epoxides.10,11 Additionally, it is known that readily available
and/or earth abundant group 1 and group 2 metals (e.g., Li,
Na, K, Mg, and Ca) are applicable to the catalytic system.12
The ionic properties of these metals seem to help in active
halide ion generation. In fact, simple metal halide salts such
12f
as LiBr12a and MgCl2 are reported to catalyze the reaction.
We therefore envisioned the creation of a highly active
catalyst by hybridizing simple metal halide salts and
phosphonium ylides L, since the addition of ligands is often
crucial for efficient conversion. This formidable challenge
inspired us to probe a premier role of phosphonium ylide L in
the Lewis base activation of a Lewis acid13 that can facilitate
the CO2 fixation.
a
bifunctional
tetraarylphosphonium
salt-derived
phosphonium ylide L (G = Me, Ar = Ph) having a privileged
structural motif, which was proven to catalyze the primary
alcohol selective acylation of mixed diols with acid
anhydrides.6 By virtue of the aryl group introduced into the
ylide carbon moiety, ylides L adopt the cis-fixed conformation
and are expected to override the C-coordination preference.
Furthermore, our recent progress in the epoxide-CO2 coupling
reactions using Brønsted acid/halide ion bifunctional catalysts
(L·HBr or L·HI) demonstrated the unique ability of L as a ligand
for proton.7 Thus, we sought to explore a novel bifunctional
At the outset of our studies, six different ligands L1-L6 were
evaluated in combination with lithium halide as a catalyst in
the CO2 fixation with epoxides 1 (Table 1). The reaction of 1,2-
epoxyhexane (1a) was performed with 10 mol % of LiI·nH2O, 5
mol % of ylide L, MS4A (0.5 g/mmol), and a balloon of CO2 in
chlorobenzene (0.3 M) at 35 °C for 24 h. The initial attempt
using L1 as a ligand afforded desired cyclic carbonate 2a in
moderate yield,14 whereas the conditions in the absence of
the ligand led to less than 5% conversion of starting material
1a. It should be noted that L1 alone could not promote the
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Table 1. Screening of Ligandsa
a) Resonance forms and coordination modes
1
O
2
3
4
5
LiI•nH2O (10 mol %)
PR3
O
PR3
O
PR3
R'
PR3
O
L
(5 mol %)
O
O
O
Me
Me
MS4A, CO2 (1 atm)
PhCl (0.3 M), 35 °C, 24 h
R'
R'
R'
O
1a
2a
I
II
III
IV
6
7
8
9
[M]
PR3
O
PR3
PR3
R'
O
PPh3
O
PPh3
PPh3
[M]
R'
R'
[M]
O
O
O
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L1
66%
L2
L3
C-coordination
cis O-coordination
trans O-coordination
31%
17%
b) Cyclic carbonate syntheses by epoxide-CO2 coupling reactions
Me
MeO
MeO
PPh3
PPh3
O
PAr3
O
O
Lewis acid/halide ion
bifunctional catalysis
O
R1
R2
O
C
O
CO2
L4
L5
L6
(Ar = 4-MeOC6H4)
94% (92%)b
+
O
R1
R2
(1 atm)
76%
83%
R3
30 ± 5 °C
R3
• Salen-Co-I (Zhou et al.)
Ph3P=O
11%
Ph3P
<5%
O
H
PPh3
Ph
H
none
<5%
PPh3
H
PPh3
I
L'
O
Et3N
<5%
Pyridine
<5%
DMAP
<5%
N
O
N
O
15%
Co
I
H
[Co]
O
tBu
tBu
bifunctional catalyst
cis O-coordination
aReaction conditions: 1.0 equiv of 1a (0.60 mmol), 10 mol % of
LiI·nH2O, 5 mol % of L, and MS4A (300 mg) under a balloon of CO2 in a
0.3 M solution of chlorobenzene at 35 °C for 24 h. Yields were
determined by 1H NMR analysis using 1,1,2,2-tetrachloroethane as an
internal standard. bIsolated yield.
tBu
tBu
)
This work
• Ylide-M-X (
G
[M]–X
G
PAr3
PAr3
X
[M] = Li, Mg, or Ca
X = Cl, Br, or I
[M]
O
O
L
ylide
bifunctional catalyst
cis O-coordination
Table 2. Effect of Ligands for Metal Halide Saltsa
O
Figure 1. Approaches to the development of a carbonyl-
stabilized phosphonium ylide-derived bifunctional catalyst
for CO2 fixation using epoxides.
metal salt (10 mol%)
L
(5 mol%)
O
O
O
Me
Me
CO2 (1 atm), MS4A
PhCl (0.3 M), 35 °C, 24 h
1a
2a
entry
1c
metal salt
LiI·nH2O
LiI
L
yield of 2a (%)b
94 (92)
98 (97)
23
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L6
L1
L1
L1
reaction at 35 °C (>99% SM recovery).15 Other Lewis bases,
2
i.e.,
triphenylphosphine
oxide,
triphenylphosphine,
3
LiBr
triethylamine, and pyridine, were also examined as control
experiments, but the reactions did not proceed efficiently. In
addition, carbonyl-stabilized phosphonium ylide L’ exhibited
insufficient reactivity. Interestingly, lower yields were
observed with the use of L2 and L3, implying the privileged
structure of L1. It is worth noting that the electronic effect of
the ligand strongly affected the reaction progress, in which
introduction of electron-donating groups into L1 enhanced
the catalyst activities.16 The highest yield of 92% was achieved
using methoxy groups-substituted ligand L6.
4
5c
LiCl
<5
NaI
55
6
7c
8c
9c
KI
<5
MgI2
91 (90)
91 (90)
64
MgBr2
MgCl2
CaI2·nH2O
CaI2
10c
11c
12c
13
14
15
90 (89)
95 (95)
79 (78)
90 (90)
93 (92)
93 (92)
BaI2·nH2O
MgI2
We next scrutinized other metal halide salts in the
presence of L6 as shown in Table 2. For epoxide 1a, there was
no significant difference between lithium iodide hydrate and
anhydrous lithium iodide (Table 2, entry 1 vs. entry 2). The
yield was decreased by switching the counterion to bromide
and chloride (Table 2, entries 3 and 4). The use of NaI with L6
CaI2·nH2O
CaI2
aAll reactions were carried out on a 0.60 mmol scale using 1a.
bDetermined by 1H NMR analysis (isolated yields are shown in
parentheses). cYield of 2a in the reaction in the absence of L:
LiI·nH2O: <5%; LiI: 9%; NaI: <5%; MgI2: 69%; MgBr2: 26%; MgCl2:
<5%; CaI2·nH2O: 18%; CaI2: 52%; BaI2·2H2O: <5%.
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The Journal of Organic Chemistry
showed moderate reactivity, but almost no product was isocyanates as an alternative reagent of CO2 were tested
1
2
3
4
5
6
7
8
obtained when KI was employed (Table 2, entries 5 and 6). In
contrast, magnesium salts such as MgI2, MgBr2, and MgCl2
gave carbonate 2a in modest to high yields (Table 2, entries 7-
9). In addition, CaI2·nH2O, CaI2, and BaI2·2H2O could be used in
conjunction with L6 (Table 2, entries 10-12). It should be
emphasized that we observed significant rate acceleration of
the reactions by the ligand addition for all metals except for
potassium. Furthermore, non-substituted ligand L1 was
applicable to the CO2 fixation in the cases of magnesium and
calcium salts (Table 2, entries 13-15).17
(Table 4). In most previous reports, harsh conditions (>100 °C)
or electron-deficient aryl isocyanates were problematic for
the oxazolidinone synthesis by [3+2] coupling reactions of
epoxides with isocyanates.7c After the screening of metal salts
and ligands, the [Mg]/L1 system was found to be superior to
other metal salt systems. The reactions using [Li]/L1 and
[Ca]/L1 afforded 3a in 11% and 65% NMR yields, respectively.
No regioisomers were observed in all cases. Selective epoxide
activation in the presence of isocyanates could be
accomplished, which is likely to be attributed to the soft
Lewis acidic character of MgI2. Phenyl isocyanate (1.2 equiv)
reacted at 35 °C with epoxides 1a, 1b, and 1e to form
oxazolidinones 3a-3c in 93-97% isolated yields.19 p-
Chlorophenyl isocyanate was accommodated efficiently,
giving rise to 3d and 3e in high yields. Moreover, p-
methoxyphenyl isocyanate was applicable to afford 3f and 3g.
Importantly, the yield of 3 decreased in the absence of L1
(e.g., yield of 3c without L1: 57%). Further screening was
focused on disubstituted epoxides shown in Scheme 1.
Although the trials under optimized conditions for
monosubstituted epoxides led to disappointing results,
careful screening enabled the reaction to proceed at ambient
pressure. LiI or CaI2 with L1 were productive for disubstituted
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Subsequently, reactions using L1 or L6 with a metal salt ([Li]
= LiI·nH2O; [Mg] = MgI2; [Ca] = CaI2·nH2O) were tested for
epoxides 1b-1h, and the results are shown in Table 3 (see
Table S3-S5 in SI for details). Epoxide 1b with a siloxy alkyl
chain, epichlorohydrin (1c), and styrene oxide (1d) underwent
CO2 fixation by [Li]/L6 catalysis to afford the corresponding
carbonates 2b-2d in 66-77% yields. Epoxide 1e bearing a
Lewis basic dibenzylaminomethyl group or 1f bearing a
benzyloxymethyl group were tolerated to furnish 2e in 73%
yield and 2f in 77% yield, wherein the use of L1 led to higher
yields than that of L6. Glycidyl ethers 1g and 1h were cleanly
converted to the cyclic carbonates, giving 2g and 2h in
excellent yields.18 For Mg-catalyzed reactions, the combined
use of MgI2 and L6 was effective in all entries (2a-2h: 80-92%
yields). On the other hand, yields of carbonates 2 tended to
increase under the influence of the [Ca]/L1 complex,
compared with those using the [Ca]/L6 complex, where
relatively good to high yields were obtained (2a-2h: 67-95%
yields). To expand the applicability of our methodology, aryl
Table 4. Scope of Mg Catalysis for the [3+2] Reaction
Between Epoxides and Isocyanatesa
MgI2 (10 mol %)
O
L1
(5 mol %)
O
O
R1
NAr
MS4A, ArNCO (1.2 equiv)
PhCl, 35 °C, 24 h
R1
1
3
Table 3. Scope of Monosubstituted Epoxides in the
Catalytic CO2 Fixationa
O
NPh
O
O
O
O
O
TBSO
NPh
NPh
metal salt (10 mol %)
metal salt
O
Bn2N
3c
nBu
3a
L
(5 mol %)
O
[Li] = LiI•nH2O
[Mg] = MgI2
O
3b
: 93%
: 96%
: 97%
R1
O
MS4A, CO2 (1 atm)
PhCl, 35 °C, 24 h
R1
1
O
O
O
O
[Ca] = CaI2•nH2O
2
O
O
O
O
NAr
NAr
NAr
NAr
Cl
Cl
O
O
O
O
nBu
Ar = 4-ClC6H4
3d
nBu
Ar = 4-MeOC6H4 Ar = 4-MeOC6H4
3f 3g
O
O
O
O
Ar = 4-ClC6H4
3e
TBSO
O
O
O
O
: 82%
: 89%
: 77%
: 93%
Cl
nBu
Ph
aAll reactions were carried out on a 0.60 mmol scale using 1 in the
presence of MgI2 (10 mol %) and L1 (5 mol %). Isolated yields are
given.
2a
L6
2b
2c
2d
L6
[Li]/ : 77%
L6
L6
[Li]/ : 66%
[Li]/ : 92%
[Li]/ : 70%
L6
L6
[Mg]/ : 92%
L6
L6
[Mg]/ : 85% [Mg]/ : 91%
[Mg]/ : 90%
L1
L1
L1
L1
[Ca]/ : 92%
[Ca]/ : 93%
[Ca]/ : 67%
[Ca]/ : 87%
O
O
O
O
Scheme 1. Scope of Disubstituted Epoxides
O
O
O
O
O
O
O
O
Bn2N
BnO
O
PhO
a)
O
LiI (30 mol %)
L1
Me
(30 mol %)
O
: 82%
O
2e
L1
2f
L1
2g
L6
2h
L6
O
Me
O
Cl
Cl
[Li]/ : 73%
[Li]/ : 77%
[Li]/ : 97%
[Li]/ : 97%
MS4A, CO2 (1 atm)
PhCl (0.3 M), 35 °C, 24 h
1i
L6
L6
L6
L6
[Mg]/ : 88%
[Mg]/ : 88%
[Mg]/ : 92%
[Mg]/ : 80%
2i
L1
L1
L1
L1
[Ca]/ : 70%
[Ca]/ : 89%
[Ca]/ : 95%
[Ca]/ : 88%
O
b)
CaI2 (10 mol %)
aAll reactions were carried out on a 0.60 mmol scale using 1 in the
presence of metal salt (10 mol %) and L1 or L6 (5 mol %). Isolated
yields are given.
O
L1
(10 mol %)
O
MS4A, CO2 (1 atm)
PhCl (0.3 M), 35 °C, 24 h
1j
2j
: 59%
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epoxides 1i and 1j (2i: 82%; 2j: 59%).20 Notably, there are few
examples of disubstituted carbonate syntheses with 1 atm
CO2 and mild temperature.11
corresponding 5-membered cyclic carbonates with moderate
1
2
3
4
5
6
7
8
to high yields. In addition, the combined use of magnesium
iodide and the ylide ligand can be applied to oxazolidinone
synthesis via [3+2] reactions between epoxides and
isocyanates. The phosphonium ylides with proper Lewis
basicity exhibit great utility as ligands in the present chemical
synthesis. Further studies to cultivate functions of the
phosphonium ylides are currently underway in our
laboratory.
In order to gain insight into the complexes formed in the
reaction mixture,21 we first performed Job plot experiments
to determine the complexation stoichiometry of LiI and L6
(Figure 2a). According to the analysis, the formation of a 1:2
complex between LiI and L6 is favored. Non-methoxy
substituted L1 also aggregates with LiI in a 1:2 fashion. ESI-
TOF high resolution mass analysis detected signals of [Li/L1]+
(m/z: Calcd 361.1329, Found 361.1306) and [Li/(L1)2]+ (m/z:
Calcd 715.2503, Found 715.2484). Next, control experiments
by changing the ratio of LiI and L6 were carried out (Figure
2b). Although the reaction of epoxide 1a proceeded
quantitatively in the presence of a 1:1 mixture of LiI and L6,
the use of an excess amount of the ligand (Li:L6 = 3:7) led to a
lower yield of carbonate 2a (85%). Thus, we concluded that
the saturated coordination complex can be generated in
equilibrium, but the active species was the 1:1 complex.
9
EXPERIMENTAL SECTION
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General Information. All reagents and solvents were
commercial grade and purified prior to use when necessary.
Thin layer chromatography (TLC) was performed using TLC
aluminum sheets from Merck (silica gel 60 F254, 200 µm), and
flash chromatography utilized silica gel from Fuji Silysia
Chemical, Ltd. (PSQ60B, 60 µm) and FUJIFILM Wako Pure
Chemical Corporation (Wakogel® C-300HG, 40-60 µm).
Products were visualized by ultraviolet (UV) light, iodine (I2),
and/or TLC stains. High-performance liquid chromatography
(HPLC) was performed on a Jasco HPLC system using Daicel
chiral columns (25 cm × 4.6 mm). Melting points were
measured on a Yanaco micro melting point apparatus and
were not corrected. Nuclear magnetic resonance (NMR)
spectra were acquired on a Bruker Fourier 300 (300 MHz).
Chemical shifts are measured relative to residual solvent
peaks as an internal standard set to 7.26 (1H) and 77.0
(13C{1H}) for CDCl3. 13C{1H} NMR peak assignments were
confirmed by DEPT 135. Data are reported as follows:
chemical shift (ppm), multiplicity (s = singlet, d = doublet, t =
triplet, q = quartet, qui = quintet, br = broad, m = multiplet),
coupling constants (Hz), and integration. Infrared (IR) spectra
were recorded on a Jasco FT/IR-4200 spectrophotometer and
are reported in wavenumbers (cm-1). All compounds were
analyzed as neat films on a potassium bromide (KBr) or
sodium chloride (NaCl) plate. Mass spectra were recorded on
a Bruker micrOTOF II mass spectrometer by the ionization
method noted. A post-acquisition gain correction was applied
using sodium formate (HCO2Na) as the lock mass. Ultraviolet-
visible light absorption (UV-Vis) spectra were recorded on a
Shimadzu UV-2450 spectrophotometer.
In summary, we have demonstrated a metal halide-based
bifunctional catalytic system for the conversion of epoxides to
cyclic carbonates under atmospheric CO2 pressure at 35 °C.
Furthermore, the function of the phosphonium ylides as
ligands was thoroughly investigated. The reactivity of lithium
iodide was enhanced by introducing methoxy groups into the
ylide ligand. Magnesium and calcium salts catalyses were also
established. Various epoxides including 1,1- and 1,2-
disubstituted epoxides were converted into the
a)
b)
Me
O
L6
LiI (5 mol %) /
O
O
Materials. The synthetic procedures and/or spectroscopic
data of L2, L3, and L4 have been already reported.6,7,22
O
CO2 (1 atm), MS4A
PhCl (0.3 M), 35 °C, 24 h
Me
1a
2a
6-(Triphenyl-5-phosphanylidene)cyclohexa-2,4-dien-1-
one (L1).22 To a solution of the phosphonium salt (L1•HBr,
653 mg, 1.5 mmol)7 in MeOH (3.0 mL) was added 10% NaOH
aq (1.8 mL), and the mixture was then stirred at rt for 0.5 h.
The mixture was treated with H2O (10 mL), and the aqueous
layer was extracted with CHCl3 (20 mL ×3). The organic layers
were combined, washed with H2O (30 mL), dried over Na2SO4,
filtered, and concentrated. The crude material was triturated
with CHCl3/hexane (1 mL/10 mL) to give L1 as a yellowish
solid (500 mg, 94%). 1H NMR (300 MHz, CDCl3)  7.73-7.60 (m,
9H), 7.55-7.49 (m, 6H), 7.35 (dddd, J = 8.7, 6.9, 1.8, 0.9 Hz,
1H), 6.71 (ddd, J = 8.7, 6.3, 0.9 Hz, 1H), 6.55 (ddd, J = 14.1, 8.1,
1.8 Hz, 1H), 6.22 (dddd, J = 8.1, 6.9, 4.5, 0.9 Hz, 1H); 13C{1H}
NMR (75 MHz, CDCl3)  176.9 (d, J = 4.4 Hz, C), 136.7 (d, J =
1.7 Hz, CH), 134.4 (d, J = 11.6 Hz, CH), 134.4 (d, J = 9.9 Hz, CH),
132.8 (d, J = 2.8 Hz, CH), 129.1 (d, J = 12.7 Hz, CH), 123.5 (d, J
7:3
6:4
5:5
4:6
3:7
(90)
(99)
(99)
(97)
(85)
L6
ratio of LiI:
Figure 2. a) Job plot of the absorbance changes at 380 nm
upon complexation of L6 with LiI. [LiI] + [L6] = 2.0 × 10-4 M in
MeCN. b) Control experiments by changing the ratio of LiI
and L6.
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4-Butyl-1,3-dioxolan-2-one (2a).7 Prepared according to
= 8.3 Hz, CH), 123.1 (d, J = 91.9 Hz, C), 110.1 (d, J = 14.3 Hz,
CH), 98.6 (d, J = 99.6 Hz, C); 31P NMR (121 MHz, CDCl3)  20.4.
1
2
the general procedure using epoxide 1a (72.3 L, 0.60 mmol).
Flash column chromatography (PSQ60B: 10 g, 10-25% EtOAc
in hexane) yielded 2a as a colorless oil ([Li]/L6: 79.9 mg, 92%).
1H NMR (300 MHz, CDCl3)  4.75-4.66 (m, 1H), 4.53 (dd, J =
8.4, 7.8 Hz, 1H), 4.07 (dd, J = 8.4, 7.2 Hz, 1H), 1.88-1.32 (m,
6H), 0.93 (t, J = 6.9 Hz, 3H). Larger scale synthesis: To an oven-
dried 30 mL round-bottom flask equipped with a stir bar was
added MgI2 (10 mol %, 83.4 mg), L1 (5 mol %, 53.2 mg), and
PhCl (0.3 M, 10 mL). After mixing the suspension at 35 °C for 5
min, activated MS4A (1.5 g) and epoxide 1a (360.7 L, 3.0
mmol) were successively added. The atmosphere was
replaced with CO2 (×3) using a diaphragm pump. The mixture
was stirred at 35 °C for 24 h under a balloon of CO2, and the
resulting mixture was then filtered on a plug of silica gel
4-Methoxy-6-(triphenyl-5-phosphanylidene)cyclohexa-
2,4-dien-1-one (L5). To a solution of the phosphonium salt
(L5•HBr, 93.1 mg, 0.20 mmol)7 in MeOH (0.40 mL) was added
10% NaOH aq (0.24 mL), and the mixture was then stirred at
rt for 0.5 h. The mixture was treated with H2O (5 mL), and the
aqueous layer was extracted with CHCl3 (10 mL ×3). The
organic layers were combined, washed with H2O (15 mL),
dried over Na2SO4, filtered, and concentrated. The crude
material was triturated with CHCl3/hexane (1 mL/10 mL) to
give L5 as a yellowish solid (67.8 mg, 88%). Rf = 0.3 (10%
MeOH/CHCl3) visualized with KMnO4; Mp 217-218 C; 1H NMR
(300 MHz, CDCl3)  7.72-7.60 (m, 9H), 7.55-7.49 (m, 6H), 7.10
(dd, J = 9.3, 3.3 Hz, 1H), 6.67 (dd, J = 9.3, 7.2 Hz, 1H), 6.04 (dd,
J = 15.0, 3.3 Hz, 1H), 3.51 (s, 3H); 13C{1H} NMR (75 MHz, CDCl3)
 173.0 (d, J = 3.3 Hz, C), 146.1 (d, J = 18.7 Hz, CH), 134.0 (d, J
= 9.9 Hz, CH), 132.9 (d, J = 3.3 Hz, CH), 129.1 (d, J = 12.7 Hz,
CH), 126.9 (d, J = 2.2 Hz, C), 124.1 (d, J = 9.9 Hz, CH), 123.0 (d,
J = 91.9 Hz, C), 116.6 (d, J = 13.2 Hz, CH), 95.8 (d, J = 100.7 Hz,
C), 56.6 (CH3); 31P NMR (121 MHz, CDCl3)  19.8; IR (NaCl)
1475, 1440, 1248, 1108, 699 cm-1; HRMS (ESI/TOF) m/z:
[M+H]+ calcd for C25H22O2P 385.1352, found 385.1359.
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(PSQ60B:
6 g) with EtOAc (50 mL). Flash column
chromatography on silica gel (PSQ60B: 25 g, 10-25% EtOAc in
hexane) yielded 2a as a colorless oil (346.0 mg, 80%).
4-(4-(tert-Butyldimethylsilyloxy)butyl-1,3-dioxolan-2-one
(2b).7 Prepared according to the general procedure using
epoxide 1b (138.3 mg, 0.60 mmol). Flash column
chromatography (PSQ60B: 15 g, 10-15% EtOAc in hexane)
1
yielded 2b as a colorless oil ([Li]/L6: 126.4 mg, 77%). H NMR
(300 MHz, CDCl3)  4.72 (dddd, J = 8.1, 7.2, 6.0, 6.0 Hz, 1H),
4.53 (dd, J = 8.4, 8.1 Hz, 1H), 4.07 (dd, J = 8.4, 7.2 Hz, 1H),
3.65-3.61 (m, 2H), 1.91-1.40 (m, 6H), 0.89 (s, 9H), 0.05 (s, 6H).
4-Methoxy-6-[tris(4-methoxyphenyl-5-
phosphanylidene)cyclohexa-2,4-dien-1-one (L6). To
a
solution of the phosphonium salt (L6•HBr, 277.7 mg, 0.50
mmol)7 in MeOH (1.0 mL) was added 10% NaOH aq (0.6 mL),
and the mixture was then stirred at rt for 0.5 h. The mixture
was treated with H2O (5 mL), and the aqueous layer was
extracted with CHCl3 (10 mL ×3). The organic layers were
combined, washed with H2O (15 mL), dried over Na2SO4,
filtered, and concentrated. The crude material was triturated
with CHCl3/hexane (1 mL/10 mL) to give L6 as a yellowish
solid (198.3 mg, 84%). Rf = 0.3 (10% MeOH/CHCl3) visualized
4-(Chloromethyl)-1,3-dioxolan-2-one
(2c).7
Prepared
according to the general procedure using epoxide 1c (47.5 L,
0.60 mmol). Flash column chromatography (PSQ60B: 15 g, 10-
25% EtOAc in hexane) yielded 2c as a colorless oil ([Li]/L6:
57.3 mg, 70%). 1H NMR (300 MHz, CDCl3)  4.96 (dddd, J = 8.2,
5.7, 5.4, 3.9 Hz, 1H), 4.60 (dd, J = 8.7, 8.2 Hz, 1H), 4.42 (dd, J =
8.7, 5.7 Hz, 1H), 3.79 (dd, J = 11.7, 5.4 Hz, 1H), 3.74 (dd, J =
11.7, 3.9 Hz, 1H).
4-Phenyl-1,3-dioxolan-2-one (2d).7 Prepared according to
the general procedure using epoxide 1d (68.3 L, 0.60 mmol).
Flash column chromatography (PSQ60B: 10 g, 10% EtOAc in
hexane) yielded 2d as a white solid ([Li]/L6: 64.7 mg, 66%). 1H
NMR (300 MHz, CDCl3)  7.49-7.34 (m, 5H), 5.68 (t, J = 8.1 Hz,
1H), 4.80 (dd, J = 8.4, 8.1 Hz, 1H), 4.35 (dd, J = 8.4, 8.1 Hz, 1H).
1
with KMnO4; Mp 201-202 C; H NMR (300 MHz, CDCl3) 
7.64-7.55 (m, 6H), 7.07 (dd, J = 9.0, 3.3 Hz, 1H), 7.03-6.98 (m,
6H), 6.66 (dd, J = 9.0, 7.5 Hz, 1H), 6.08 (dd, J = 15.3, 3.3 Hz,
1H), 3.86 (s, 3H), 3.54 (s, 3H); 13C{1H} NMR (75 MHz, CDCl3) 
171.9 (C), 163.1 (d, J = 3 Hz, C), 146.1 (d, J = 19 Hz, C), 135.8 (d,
J = 12 Hz, CH), 126.0 (d, J = 2 Hz, CH), 123.9 (d, J = 10 Hz, CH),
117.3 (d, J = 13 Hz, CH), 114.8 (d, J = 13.8 Hz, CH), 113.9 (d, J =
99 Hz, C), 98.3 (d, J = 101 Hz, C), 56.7 (CH3), 55.5 (CH3); 31P
NMR (121 MHz, CDCl3)  19.0; IR (KBr) 1595, 1501, 1476, 1296,
1260, 1182, 1110, 1023, 831 cm-1; HRMS (ESI/TOF) m/z:
[M+H]+ calcd for C28H28O5P 475.1669, found 475.1690.
4-((Dibenzylamino)methyl)-1,3-dioxolan-2-one
(2e).7
Prepared according to the general procedure using epoxide
1e (152.0 mg, 0.60 mmol). Flash column chromatography
(PSQ60B: 10 g, 10-20% EtOAc in hexane) yielded 2e as a
1
colorless oil ([Li]/L1: 130.7 mg, 73%). H NMR (300 MHz,
General Procedure for the Reactions of CO2 with Epoxides.
To an oven-dried test tube equipped with a stir bar was
added metal salt (10 mol %, LiI•nH2O: 8.0 mg; MgI2: 16.6 mg;
CaI2•nH2O: 17.6 mg), ligand (5 mol %, L1: 10.6 mg; L6: 14.3
mg), and PhCl (0.3 M, 2.0 mL). After mixing the suspension at
35 °C for 5 min, activated MS4A (300 mg) and epoxide 1 (0.60
mmol, 1.0 equiv) were successively added. The atmosphere
was replaced with CO2 (×3) using a diaphragm pump. The
mixture was stirred at 35 °C for 24 h under a balloon of CO2,
and the resulting mixture was then filtered on a plug of silica
gel (PSQ60B: 6 g) with EtOAc (50 mL). Flash column
chromatography on silica gel yielded the corresponding cyclic
carbonate 2.
CDCl3)  7.37-7.24 (m, 10H), 4.58 (dddd, J = 7.8, 6.6, 6.6, 5.4
Hz, 1H), 4.25 (dd, J = 8.4, 7.8 Hz, 1H), 3.90 (dd, J = 8.4, 6.6 Hz,
1H), 3.70 (d, J = 13.5 Hz, 2H), 3.64 (d, J = 13.5 Hz, 2H), 2.83 (dd,
J = 13.8, 5.4 Hz, 1H), 2.76 (dd, J = 13.8, 6.6 Hz, 1H).
4-(Benzyloxymethyl)-1,3-dioxolan-2-one (2f).7 Prepared
according to the general procedure using epoxide 1f (92.1 L,
0.60 mmol). Flash column chromatography (PSQ60B: 20 g, 10-
30% EtOAc in hexane) yielded 2f as a colorless oil ([Li]/L1:
96.4 mg, 77%). 1H NMR (300 MHz, CDCl3)  7.40-7.28 (m, 5H),
4.81 (dddd, J = 8.4, 6.0, 4.2, 3.9 Hz, 1H), 4.63 (d, J = 12.0 Hz,
1H), 4.57 (d, J = 12.0 Hz, 1H), 4.48 (t, J = 8.4 Hz, 1H), 4.39 (dd,
J = 8.4, 6.0 Hz, 1H), 3.70 (dd, J = 10.8, 4.2 Hz, 1H), 3.62 (dd, J =
10.8, 3.9 Hz, 1H).
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4-(Allyloxymethyl)-1,3-dioxolan-2-one (2g).7 Prepared
according to the general procedure using epoxide 1g (70.8 L,
0.60 mmol). Flash column chromatography (PSQ60B: 10 g, 10-
20% EtOAc in hexane) yielded 2g as a colorless oil ([Li]/L6:
92.4 mg, 97%). 1H NMR (300 MHz, CDCl3)  5.88 (ddt, J = 17.1,
10.2, 5.4 Hz, 1H), 5.29 (dq, J = 17.1, 1.5 Hz, 1H), 5.23 (dq, J =
10.2, 1.5 Hz, 1H), 4.84 (ddt, J = 8.4, 6.0, 3.9 Hz, 1H), 4.51 (t, J =
8.4 Hz, 1H), 4.40 (dd, J = 8.4, 6.0 Hz, 1H), 4.06 (dt, J = 5.4, 1.5
Hz, 2H), 3.71 (dd, J = 11.1, 3.9 Hz, 1H), 3.62 (dd, J = 11.1, 3.9
Hz, 1H).
4-(Phenoxymethyl)-1,3-dioxolan-2-one (2h).7 Prepared
according to the general procedure using epoxide 1h (81.2 L,
0.60 mmol). Flash column chromatography (PSQ60B: 10 g, 10-
30% EtOAc in hexane) yielded 2h as a white solid ([Li]/L6:
113.3 mg, 97%). 1H NMR (300 MHz, CDCl3)  7.34-7.27 (m, 2H),
7.04-6.99 (m, 1H), 6.93-6.89 (m, 2H), 5.03 (dddd, J = 8.4, 6.0,
4.2, 3.6 Hz, 1H), 4.62 (t, J = 8.4 Hz, 1H), 4.53 (dd, J = 8.4, 6.0
Hz, 1H), 4.24 (dd, J = 10.5, 4.2 Hz, 1H), 4.15 (dd, J = 10.5, 3.6
Hz, 1H).
was stirred at 80 °C for 24 h under a balloon of CO2. Flash
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7
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column chromatography on silica gel (PSQ60B: 15 g, 10-40%
EtOAc in hexane) yielded 2k (55.8 mg, 65%) as a colorless
plate. mp 33-34 C; 1H NMR (300 MHz, CDCl3)  4.73-4.66 (m,
2H), 1.93-1.88 (m, 4H), 1.69-1.57 (m, 2H), 1.49-1.37 (m, 2H);
13C{1H} NMR (75 MHz, CDCl3)  155.3 (C), 75.7 (CH), 26.7 (CH2),
19.1 (CH2); IR (KBr) 2946, 2869, 1801, 1353, 1208, 1168, 1141,
1032, 996, 782, 731 cm-1; HRMS (ESI/TOF) m/z: [M+Na]+ calcd
for C7H10NaO3 165.0522, found 165.0520.
9
General Procedure for the Reactions of Isocyanates with
Epoxides. To an oven-dried test tube equipped with a stir bar
was added MgI2 (10 mol %, 16.6 mg), L1 (5 mol %, 10.6 mg),
and PhCl (0.3 M, 2.0 mL). After mixing the suspension at 35 °C
for 5 min, activated MS4A (300 mg), epoxide 1 (0.60 mmol,
1.0 equiv), and isocyanate (0.72 mmol, 1.2 equiv) were
successively added. The mixture was stirred at 35 °C for 24 h,
and the resulting mixture was then filtered on a plug of silica
gel (PSQ60B: 6 g) with EtOAc (50 mL). Flash column
chromatography on silica gel yielded the corresponding
oxazolidinone 3.
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4-(Chloromethyl)-4-methyl-1,3-dioxolan-2-one (2i).23 To an
oven-dried test tube equipped with a stir bar was added LiI
(24.3 mg, 30 mol %), L1 (63.7 mg, 30 mol %), and PhCl (2.0 mL,
0.3 M). After mixing the suspension at 35 °C for 5 min,
activated MS4A (300 mg) and epoxide 1j (57.6 L, 0.60 mmol)
were successively added. The atmosphere was replaced with
CO2 (×3) using a diaphragm pump. The mixture was stirred at
35 °C for 24 h under a balloon of CO2. Flash column
chromatography on silica gel (PSQ60B: 15 g, 10-50% EtOAc in
5-Butyl-3-phenyloxazolidin-2-one
(3a).7
Prepared
according to the general procedure using epoxide 1a (72.3 L,
0.60 mmol) and phenyl isocyanate (78.3 L, 0.72 mmol). Flash
column chromatography (PSQ60B: 12 g, 5% EtOAc in hexane)
1
yielded 3a (122.2 mg, 93%) as a white solid. H NMR (300
MHz, CDCl3)  7.56-7.52 (m, 2H), 7.40-7.34 (m, 2H), 7.16-7.10
(m, 1H), 4.68-4.59 (m, 1H), 4.08 (t, J = 8.7 Hz, 1H), 3.66 (dd, J =
8.7, 7.2 Hz, 1H), 1.92-1.67 (m, 2H), 1.57-1.34 (m, 4H), 0.96-
0.92 (m, 3H).
1
hexane) yielded 2i (73.8 mg, 82%) as a yellowish oil. H NMR
(300 MHz, CDCl3)  4.52 (d, J = 8.9 Hz, 1H), 4.17 (d, J = 8.9 Hz,
1H), 3.73 (d, J = 12.0 Hz, 1H), 3.60 (d, J = 12.0 Hz, 1H), 1.64 (s,
3H); 13C{1H} NMR (75 MHz, CDCl3)  153.7 (C), 81.7 (C), 72.0
(CH2), 48.2 (CH2), 23.0 (CH3); HRMS (ESI/TOF) m/z: [M+Na]+
calcd for C5H7ClNaO3 172.9976, found 172.9961.
5-(4-(tert-Butyldimethylsilyloxy)butyl-3-phenyloxazolidin-
2-one (3b).7 Prepared according to the general procedure
using epoxide 1b (138.6 mg, 0.60 mmol) and phenyl
isocyanate (78.3 L, 0.72 mmol). Flash column
chromatography (PSQ60B: 28 g, 8-10% EtOAc in hexane)
1
3a,8a-Dihydro-8H-indeno[1,2-d]-1,3-dioxol-2-one (2j).24 To
an oven-dried test tube equipped with a stir bar was added
CaI2 (17.5 mg, 10 mol %), L1 (21.2 mg, 10 mol %), and PhCl
(2.0 mL, 0.3 M). After mixing the suspension at 35 °C for 5 min,
activated MS4A (300 mg) and 1j (70.4 L, 0.60 mmol) were
successively added. The atmosphere was replaced with CO2
(×3) using a diaphragm pump. The mixture was stirred at
35 °C for 24 h under a balloon of CO2. Flash column
chromatography on silica gel (PSQ60B: 17 g, 20% EtOAc in
hexane) yielded 2j (62.6 mg, 59%) as a reddish solid (mp 73-
yielded 3b (200.8 mg, 96%) as a white solid. H NMR (300
MHz, CDCl3)  7.55-7.52 (m, 2H), 7.40-7.34 (m, 2H), 7.16-7.10
(m, 1H), 4.69-4.60 (m, 1H), 4.09 (t, J = 8.7 Hz, 1H), 3.69-3.62
(m, 3H), 1.95-1.70 (m, 2H), 1.65-1.47 (m, 4H), 0.89 (s, 9H),
0.05 (s, 6H).
5-((Dibenzylamino)methyl)-3-phenyloxazolidin-2-one
(3c).7 Prepared according to the general procedure using
epoxide 1e (152.2 mg, 0.60 mmol) and phenyl isocyanate
(78.3 L, 0.72 mmol). Flash column chromatography
(PSQ60B: 12 g, 8-10% EtOAc in hexane) yielded 3c (220.3 mg,
1
74 C). H NMR (300 MHz, CDCl3)  7.51 (dt, J = 7.5, 0.6 Hz,
1
97%) as a white solid. H NMR (300 MHz, CDCl3)  7.42-7.21
1H), 7.45-7.31 (m, 3H), 6.01 (d, J = 6.6 Hz, 1H), 5.45 (ddd, J =
6.9 Hz, 4.8 Hz, 3.0 Hz, 1H), 3.47-3.34 (m, 2H); 13C{1H} NMR (75
MHz, CDCl3)  154.7 (C), 140.0 (C), 136.4 (C), 131.0 (CH), 128.1
(CH), 126.4 (CH), 125.6 (CH), 83.5 (CH), 79.7 (CH), 37.9 (CH2);
HRMS (ESI/TOF) m/z: [M+Na]+ calcd for C10H8NaO3 199.0366,
found 199.0365.
4,5-Tetramethylene-1,3-dioxolan-2-one (2k).24 To an oven-
dried test tube equipped with a stir bar was added CaI2 (17.5
mg, 10 mol %), L1 (21.2 mg, 10 mol %), and PhCl (2.0 mL, 0.3
M). After mixing the suspension at 35 °C for 5 min, activated
MS4A (300 mg) and 1,2-epoxycyclohexane (60.7 L, 0.60
mmol) were successively added. The atmosphere was
replaced with CO2 (x 3) using a diaphragm pump. The mixture
(m, 14H), 7.14-7.09 (m, 1H), 4.61-4.52 (m, 1H), 3.80 (t, J = 8.7
Hz, 1H), 3.76 (d, J = 13.5 Hz, 2H), 3.66 (d, J = 13.5 Hz, 2H), 3.50
(dd, J = 8.7, 6.6 Hz, 1H), 2.86 (dd, J = 13.5, 5.4 Hz, 1H), 2.81
(dd, J = 13.5, 6.6 Hz, 1H).
5-Butyl-3-(4-chlorophenyl)oxazolidin-2-one
(3d).25
Prepared according to the general procedure using epoxide
1a (72.3 L, 0.60 mmol) and 4-chlorophenyl isocyanate (92.1
L, 0.72 mmol). Flash column chromatography (PSQ60B: 35 g,
5% EtOAc in hexane) yielded 3d (125.7 mg, 82%) as a white
solid. 1H NMR (300 MHz, CDCl3)  7.52-7.46 (m, 2H), 7.35-7.30
(m, 2H), 4.69-4.59 (m, 1H), 4.05 (t, J = 8.4 Hz, 1H), 3.62 (dd, J =
8.4, 7.2 Hz, 1H), 1.93-1.67 (m, 2H), 1.56-1.33 (m, 4H), 0.99-
0.92 (m, 3H); 13C{1H} NMR (75 MHz, CDCl3) δ 154.7 (C), 137.0
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The Journal of Organic Chemistry
(C), 129.0 (C), 128.9 (CH), 119.2 (CH), 73.1 (CH), 50.3 (CH2),
Other Authors
Kousuke Hashimoto – Shinshu University, 4-17-1 Wakasato,
Nagano 380-8553, Japan
Yoko Mori – Shinshu University, 4-17-1 Wakasato, Nagano 380-
8553, Japan
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34.6 (CH2), 26.5 (CH2), 22.3 (CH2), 13.8 (CH3); IR (KBr) 2954,
2869, 1728, 1497, 1377, 1312, 1217, 1096, 831, 754 cm-1;
HRMS (ESI/TOF) m/z: [M+Na]+ calcd for C13H16ClNNaO2
276.0762, found 276.0773.
5-(Chloromethyl)-3-(4-chlorophenyl)oxazolidin-2-one
(3e).7 Prepared according to the general procedure using
epoxide 1c (47.0 L, 0.60 mmol) and 4-chlorophenyl
isocyanate (92.1 L, 0.72 mmol). Flash column
chromatography (Wakogel C-300HG: 12 g, 15-20% EtOAc in
Complete contact information is available at:
https://pubs.acs.org/
Notes
9
The authors declare no competing financial interest.
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hexane) yielded 3e (131.0 mg, 89%) as a white solid. H NMR
(300 MHz, CDCl3)  7.52-7.47 (m, 2H), 7.37-7.32 (m, 2H), 4.92-
4.84 (m, 1H), 4.15 (t, J = 9.0 Hz, 1H), 3.94 (dd, J = 9.0, 5.7 Hz,
1H), 3.80 (dd, J = 11.7, 4.2 Hz, 1H), 3.75 (dd, J = 11.7, 6.3 Hz,
1H).
ACKNOWLEDGMENTS
This work was partially supported by the Japan Society for the
Promotion of Science (JSPS) through a Grant-in-Aid for Young
Scientists (B) (Grant No. JP17K14483) and Scientific Research (C)
(Grant No. JP17KT0096). We gratefully acknowledge funding
from the alumni association “Wakasatokai” of the Faculty of
Engineering, Shinshu University. We are extremely thankful to
Yutaka Komiyama for his kind support.
5-Butyl-3-(4-methoxyphenyl)oxazolidin-2-one
(3f).25
Prepared according to the general procedure using epoxide
1a (72.3 L, 0.60 mmol) and 4-methoxyphenyl isocyanate
(93.5 L, 0.72 mmol). Flash column chromatography
(PSQ60B: 45 g, 5-15% EtOAc in hexane) yielded 3f (115.0 mg,
1
REFERENCES
77%) as a white solid. H NMR (300 MHz, CDCl3)  7.46-7.40
(m, 2H), 6.93-6.88 (m, 2H), 4.66-4.57 (m, 1H), 4.04 (t, J = 8.7
Hz, 1H), 3.80 (s, 3H), 3.62 (dd, J = 8.7, 7.2 Hz, 1H), 1.90-1.66
(m, 2H), 1.56-1.33 (m, 4H), 0.96-0.91 (m, 3H); 13C{1H} NMR (75
MHz, CDCl3) δ 156.2 (C), 155.2 (C), 131.6 (C), 120.0 (CH),
114.2 (CH), 73.0 (CH), 55.4 (CH3), 50.9 (CH2), 34.6 (CH2), 26.6
(CH2), 22.3 (CH2), 13.8 (CH3); IR (KBr) 2953, 1720, 1522, 1439,
1414, 1282, 1259, 1235, 1152, 822, 756 cm-1; HRMS (ESI/TOF)
m/z: [M+Na]+ calcd for C14H19NNaO3 272.1257, found
272.1263.
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5-(Chloromethyl)-3-(4-methoxyphenyl)oxazolidin-2-one
(3g).7 Prepared according to the general procedure using
epoxide 1c (47.0 L, 0.60 mmol) and 4-methoxyphenyl
isocyanate (93.5 L, 0.72 mmol). Flash column
chromatography (Wakogel C-300HG: 14 g, 20-50% EtOAc in
hexane; 28 g, 100% CHCl3) yielded 3g (135.5 mg, 93%) as a
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Chauvin,
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Ylide
Chiral
Ligands:ꢀ
Phosphino(sulfinylmethyl)triarylphosphonium
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Functionalized Phosphine (YPhos)–Palladium Catalysts: Selective
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1
white solid. H NMR (300 MHz, CDCl3)  7.46-7.41 (m, 2H),
6.94-6.89 (m, 2H), 4.89-4.81 (m, 1H), 4.14 (t, J = 9.0 Hz, 1H),
3.92 (dd, J = 9.0, 5.7 Hz, 1H), 3.81 (s, 3H), 3.80 (dd, J = 11.7,
4.5 Hz, 1H), 3.74 (dd, J = 11.7, 6.6 Hz, 1H).
ASSOCIATED CONTENT
The Supporting Information is available free of charge via the
Internet at http://pubs.acs.org. 1H NMR and 13C{1H} NMR spectra
for all new compounds and 1H NMR spectra of known
compounds 2 and 3.
AUTHOR INFORMATION
Corresponding Authors
Yasunori Toda - Department of Materials Chemistry, Faculty of
Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-
8553, Japan; orcid.org/0000-0001-9725-9438
Email: ytoda@shinshu-u.ac.jp
(3) (a) Johnson, A. W. Ylides and imines of phosphorus, Wiley: New
York, 1993. (b) Taillefer, M.; Cristau, H.-J. In New Aspects in
Phosphorus Chemistry III; Majoral, J.-P. Ed.; Springer: New York,
2003; Chapter 2, pp 41-73. (c) Urriolabeitia, E. P. In Transition Metal
Complexes of Neutral 1-Carbon Ligands; Chauvin, R.; Canac, Y. Eds.;
Hiroyuki Suga - Department of Materials Chemistry, Faculty of
Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-
8553, Japan; orcid.org/0000-0001-8977-4691
Email: sugahio@shinshu-u.ac.jp
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Springer: New York, 2010; Chapter 2, pp 15-48. Selected recent
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(Benzoylmethylene)triphenylphosphorane). Molecular Structure of
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Cooperative Multifunctional Organocatalysts for Ambient Conversion
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{Pd(dmba)(py)[OC(CH3)=C(H)PPh3]}(ClO4)·CH2Cl2.
Unusual
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Coordination of the (Acetylmethylene)triphenylphosphorane Ligand
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Potassium Iodide–Tetraethylene Glycol Complex as a Practical
Catalyst for CO2 Fixation Reactions with Epoxides under Mild
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Carbonates by MgII/Phosphine-Catalyzed Coupling Reactions of
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(h) Longwitz, L.; Steinbauer, J.; Spannenberg, A.; Werner, T. Calcium-
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(14) The reaction using LiI·nH2O (10 mol %) and L1 (5 mol %)
without MS4A afforded 2a in 20% NMR yield.
(15) The reaction using tetraarylphosphonium salt L1·HI (5 mol %)
under the same conditions afforded 2a in 10% NMR yield.
(16) The energies of highest occupied molecular orbital (HOMO)
were obtained by DFT calculations (L6: −1.43 eV; L1: −1.55 eV; L’:
−1.68 eV).
(17) Due to easy preparation, L1 was used rather than L4 or L5.
(18) The reaction using (S)-1h (>99% ee) afforded (R)-2h in 90%
yield with 99% ee (retention).
(19) The reaction using 1a and phenyl isocyanate (1.2 equiv) in the
presence of MgI2 (2 mol %) and L1 (1 mol %) in PhCl (3.0 M) at 30 °C
for 24 h afforded 3a in 51% NMR yield.
(20) The reaction using cyclohexene oxide (1k) in the presence of
CaI2 (10 mol %) and L1 (10 mol %) at 80 °C for 24 h afforded
cyclohexene carbonate (2k) in 65% yield.
(21) Zhou, Lu, and co-workers reported the CO2 adducts of
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corresponding CO2 adduct that serves as a catalyst. However, we
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could not obtain any spectroscopic date of the CO2 adducts of L.
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(24) Miceli, C.; Rintjema, J.; Martin, E.; Escudero-Adán, E. C.; Zonta,
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O
phosphonium ylides
& metal salts
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O
O
R1
R3
O
CO2 (1 atm)
R2
R1
R3
35 °C
R2
Lewis acid/halide ion bifunctional catalysis
atmosperic pressure mild conditions
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