Multicomponent Reaction of Phosphines, Benzynes, and CO2: Facile Synthesis of Stable Zwitterionic Phosphonium Inner Salts

Article abstract of DOI:10.1021/acs.joc.0c00745

The first synthesis of benzyne-derived stable zwitterions is reported. Benzynes generated in situ from 2-(trimethylsilyl)aryl triflates undergo a multicomponent reaction with phosphines and CO2 to produce the stable 1,5-zwitterionic species in moderate to excellent isolated yields, which provides a novel method for the preparation of phosphonium inner salts under mild and transition-metal-free conditions.

Full text of DOI:10.1021/acs.joc.0c00745

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Article
Multicomponent reaction of phosphines, benzynes and CO2:
facile synthesis of stable zwitterionic phosphonium inner-salts
Pei Xie, Shoushan Yang, Yuyu Guo, Zhihua Cai, Bin Dai, and Lin He
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.0c00745 • Publication Date (Web): 25 Jun 2020
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Multicomponent reaction of phosphines, benzynes and CO2:
facile synthesis of stable zwitterionic phosphonium inner-
salts
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Pei Xie, Shoushan Yang, Yuyu Guo, Zhihua Cai*, Bin Dai and Lin He*
Key Laboratory for Green Processing of Chemical Engineering of Xinjiang
Bingtuan, School of Chemistry and Chemical Engineering, Shihezi
University, Xinjiang Uygur Autonomous Region 832000, China.
* Email: caizhihua1986@sina.cn; helin@shzu.edu.cn
Abstract: The first synthesis of benzyne derived stable zwitterions is
reported. Benzynes generated in situ from 2-(trimethylsilyl)aryl triflates
undergo multicomponent reaction with phosphines and CO2 to produce the
stable 1,5-zwitterionic species in moderate to excellent isolated yields,
which provides a novel method for the preparation of phosphonium inner-
salts under mild and transition-metal free conditions.
Introduction:
The past two decades have witnessed remarkable progress in
benzyne chemistry.1 As one of the most versatile building blocks,
benzynes have been used widely in a broad variety of reactions, such
as pericyclic reactions,2 insertion reactions,3 multicomponent
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reactions (MCRs)4 and others.5 These reactions provide efficient
methods for the construction of carbon-carbon and carbon-
heteroatom bonds. In particular, the highly electrophilic properties of
benzynes enable them to be readily attacked by different nucleophiles
to generate an aryl anion or 1,3-zwitterionic species, which can
further react with the third electrophilic component to produce
various 1,2-disubstituted benzene derivatives.
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On the other hand, the utilization of CO2 as non-toxic, renewable,
inexpensive and easy-available one carbon (C1) feedstock to prepare
value-added chemicals has received considerable attention in recent
years.6 Generally, CO2 is used as an electrophile regardless of its
intrinsic thermodynamic and kinetic stability. Although several
excellent MCRs involving benzynes, CO2 and different nucleophiles
have been reported in recent years, the studies of the incorporation of
CO2 in the reaction of benzynes are still very limited. In 2006,
Yoshida, Kunai and coworkers reported the first incorporation of CO2
in MCR of benzynes7 (Scheme 1, eq. a). They found that imines can
be employed as nucleophiles to trigger the three-component coupling
involving benzynes and CO2, giving benzoxazinones efficiently.
Later, Biju and coworkers8 reported an interesting MCR of
isocyanides, benzynes and CO2 to produce phthalimides as the final
products, which were assumed to be formed through fluoride-induced
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rearrangement of the iminoisobenzofuranone intermediates (Scheme
1, eq. b). In 2008, Yoshida and coworkers9 documented a concise
three-component coupling of benzynes, secondary amines and CO2,
furnishing anthranilic acids directly (Scheme 1, eq. c). Interestingly,
with the introduction of aromatic tertiary amines to the reaction, Biju
and coworkers10 developed a novel substrate-controlled switchable
MCR involving benzynes and CO2, delivering two different types of
2-aminoaryl benzoates selectively (Scheme 1, eq. c). Recently,
Jiang and coworkers11a disclosed a new three-phase four-component
coupling reaction involving benzynes. In that reaction, KCl was used
as nucleophile to attack the carbon-carbon triple bond of benzyne and
trigger the MCR of benzynes with incorporation of CO2, giving o-
chlorobenzoates as the major products. More interestingly, the same
group uncovered11b that allyl bromides can function as
unconventional nucleophiles to alert the MCR of benzynes to provide
the bromocarboxylation products (Scheme 1, eq. d). In these
aforementioned MCRs, the benzyne-derived zwitterionic species are
the key intermediates, which readily undergo the following
nucleophilic attack to furnish the corresponding products.
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Scheme 1. MCRs involving benzynes and CO2
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However, these zwitterions are unstable and have not been
successfully prepared. With our continuing interest in benzyne
chemistry,12 we found that phosphines, benzynes and CO2 can
undergo three-component coupling reaction to produce zwitterionic
species as the unexpected final products.13 These stable zwitterions,
also named as phosphonium salts, are a unique type of P(V)
compounds that used widely as organocatalysts,14 organic reagents,15
ionic liquids,16 ligands17 and others18 in organic chemistry. Herein, we
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would like to report our preliminary results on the synthesis of
zwitterionic phosphonium inner-salts through MCR involving
benzynes and CO2.
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Results and Discussion:
To start our investigation, the commercially available Kobayashi's
precursor 1a19 and triphenylphosphine 2a were selected as the model
substrates for the optimization of the reaction (Table 1). To our
delight, with 2.0 equiv of KF and 18-crown-6 as additives, the MCR
smoothly proceeded in THF under 1 atm CO2 at room temperature to
provide phosphonium inner-salt 3aa in 91% NMR yield (Table 1,
entry 1). Encouraged by this success, other common fluoride sources
were subsequently tested for the reaction. In the absence of 18-crown-
6, KF or CsF cannot promote the coupling (Table 1, entries 2 and 3).
Tetrabutylammonium difluorotriphenylsilicate (TBAT) promoted
the reaction in high yield (Table 1, entry 4). Both
tetrabutylammonium fluoride (TBAF) and tetramethylaminium
fluoride (TMAF) showed low efficiency (Table 1, entries 5 and 6).
Shorten the reaction time to 10 h, the reaction yield was slightly
improved to 94% (Table 1, entry 7). A brief screening of the reaction
media showed that THF was still the best choice in terms of yield
(Table 1, entries 8-11). Reducing KF and 18-crown-6 to 1.5 equiv,
the product can still be formed in 90% yield (Table 1, entry 12).
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However, lowering the additives loading to 1.2 equiv resulted in
obvious decrease of the reaction yield (Table 1, entry 13). Finally, in
the presence of 1.5 equiv KF/18-crown-6 and prolonged the reaction
time to 24 h, the desired product was obtained in 96% NMR yield and
91% isolated yield (Table 1, entry 14).
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Table 1. Optimization of reaction conditionsa
entry
1
[F] source (equiv)
KF(2)+18-C-6(2)
KF(2)
solvent t (h) yield (%)b
THF
THF
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10
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91
0
2
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CsF(2)
THF
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TBAT(2)
THF
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TBAF(2)
THF
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TMAT(2)
THF
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KF(2)+18-C-6(2)
KF(2)+18-C-6(2)
KF(2)+18-C-6(2)
KF(2)+18-C-6(2)
KF(2)+18-C-6(2)
KF(1.5)+18-C-6(1.5)
KF(1.2)+18-C-6(1.2)
KF(1.5)+18-C-6(1.5)
THF
94
8
CH3CN
DME
69
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61
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Dioxane 10
40
Toluene
THF
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10
10
24
8
90
THF
75
96(91)c
THF
a Reaction conditions: 1a (0.24 mmol), 2a (0.2 mmol), CO2 (1at
o
b
m), 0 C-rt; NMR yield using CH2Br2 (0.2 mmol, 14 μL) as
internal standard; c isolated yield.
The product 3aa was crystallized from ethyl acetate and n-hexane,
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and its structure was clearly confirmed by single-crystal X-ray
analysis.20
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With the optimized reaction condition in hand, we then examined
the scope of phosphines (Scheme 2). Both electron-donating and
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electron-withdrawing
participated in the MCR smoothly to produce the corresponding
zwitterionic phosphonium inner-salts in excellent yield (3ab 3ae). In
groups
substituted
triarylphosphines
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addition, triarylphosphines bearing substituent at the meta-position of
the benzene ring underwent the reaction to afford the corresponding
inner-salts efficiently (3af-3ai). However, when tri-o-tolylphosphine
2j was used for the reaction, only trace amount of the desired product
was formed under the standard reaction conditions. Pleasingly, the
reaction yield can be improved to 65% with elevated reaction
temperature and prolonged reaction time (3aj). But unfortunately,
when the fully ortho-substituted triarylphosphine 2k was employed
for the MCR, no desired product was obtained and the starting
phosphine 2k was recovered in high yield (3ak). We attributed these
results to the dramatic increase of the steric hindrance of
triarylphosphines. Interestingly, the bulky phosphines 2l and 2m
performed the MCR well to give phosphonium inner-salts 3al and
3am in 84% and 40% yields, respectively. Heteroaryl substituted
phosphine 2n was proven to be a successful candidate for the reaction,
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providing 3an in 71% yield. However, in case of tri-2-furylphosphine
2o, the MCR with benzyne and CO2 was complex and only 20% yield
product was obtained (3ao). Both mono- and dialkyl-substituted
phosphines performed the reaction very well, affording the desired
products in satisfactory yield (3ap and 3aq). Surprisingly, when
trialkyl-substituted phosphine was used for the reaction, the reaction
was complex and the desired product was obtained in very low yield
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(
3ar). The similar triarylarsane was also tested for the MCR and the
corresponding arsonium salt 3as was obtained in 88% yield.
Scheme 2. Subsrate scope of triarylphosphine compoundsa
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a Reaction conditions: 1a (0.24 mmol), 2 (0.2 mmol), CO2 (1 atm),
KF (3.0 mmol), 18-crown-6 (0.3 mmol), 0 oC-rt, 24h and isolated
yield. b 50 oC, 36 h. c Phosphine 2k was recovered in 90% yield.
d 0 -10 oC, 24 h. n.d. (not detected).
Next, we investigated substituted benzyne precursors for the MCR
(Scheme 3). Symmetrical benzynes with both electron-donating and
electron-withdrawing
groups
at
4,5-positions
reacted
with
triphenylphosphine and CO2 to produce the corresponding phosphonium
salts in moderate to high yields (3ba-3fa). Notably, 3,6-dimethyl
substituted benzyne that with steric hindrance around the carbon-carbon
triple bond underwent the MCR to yield 3ga in 51% yield. The symmetrical
naphthalene was suitable reactant for the reaction, furnishing the
phosphonium salt in 83% yield (3ha). In addition, the unsymmetrical
benzynes that derived from precursors 1i, 1j and 1k, underwent the three-
component coupling efficiently to provide the corresponding products in
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good yields and moderate regioselectivity (3ia-3ka). The pure
regioisomers 3ia and 3ia’, 3ka and 3ka’ can be obtained via column
chromatography. However, regioisomers 3ja and 3ja’ cannot be isolated
completely and only the pure product of the major regioisomer 3ja was
isolated.
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Scheme 3. Subsrate scope of benzyne precursorsa
a Reaction conditions:
1 (0.24 mmol), 2a (0.2 mmol), CO2
(1 atm), KF (3.0 mol), 18-crown-6 (0.3 mmol), 40 oC, 36 h and
isolated yield.
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To demonstrate the synthetic utility of this methodology, we
carried out the MCR on gram scale by treatment of
triphenylphosphine and Kobayashi’s precursor 1a under 1 atm of CO2.
The phosphonium inner-salt 3aa was obtained in 1.42g and 93%
isolated yield under the standard reaction conditions (Scheme 4).
Scheme 4. Gram-scale preparation of 3aa
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Based on the pioneering studies of three-component coupling
reaction involving benzynes and CO2,7-11 two plausible reaction
mechanisms were proposed as depicted in Scheme 5. For path a, the
fluoride induced 1,2-elimination of 2-(trimethylsilyl)aryl triflate
results in the in situ generation of benzyne. The following
nucleophilic attack of triphenylphosphine will trigger the tandem
reaction and lead to the formation of the final zwitterionic
phosphonium inner-salt. For path
cycloaddition with CO2 to generate intermediate
subsequently undergoes ring-opening reaction
b, benzyne might undergo [2+2]
I, which
with
triphenylphosphine to produce the final product.
Scheme 5. Proposed mechanism
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The control experiment showed that in the absence of triphenylphosphine,
benzyne can react with CO2 to produce xanthone 4a in 18% yield
(Scheme 6). We concluded that benzyne firstly undergo [2+2]
reaction with CO2 to generate intermediate
I. Owing to the high ring
strain of the four-membered ring, undergoes ring-opening reaction
I
to produce ketene intermediate II, which couples with the second
molecular of benzyne via [4+2] reaction to afford 4a. This result
indicates the possibility of the formation of intermediate I.
Scheme 6. The reaction of benzyne and CO2
Conclusions:
In summary, we have developed an efficient and practical approach for
the synthesis of stable zwitterionic phosphonium inner-salts through the
three-component coupling reaction of benzynes, phosphines and CO2. The
presented protocol features mild and transition-metal free conditions,
simple operation and ready scalability. Further studies on the synthesis of
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chiral P-stereogenic phosphonium inner-salts and their applications in
organic synthesis are currently underway in our laboratory.
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EXPERIMENTAL SECTION
General experimental methods
Unless otherwise indicated, all reactions were conducted in oven-dried 50
mL Schlenk sealed tube (Synthware) under a CO2 atmosphere. CO2 was
provided by Shanghai Weichuang Standard Gas and its purity was ≥
99.999%. Benzyne precursors and other commercial available reagents
were obtained from commercial suppliers (such as Adamas, Strem, J&K
Chemical Co., Energy Chemical. etc), and used without purification.
Benzyne precursors 1b, 1d, 1e-1g, and 1j-1k were prepared according to
literature procedures.3f, 11b, 21 Anhydrous THF, dioxane, CH3CN, toluene
and DME were obtained from commercial suppliers. 1H, 13C and 31P NMR
spectra were recorded on a Bruker AVANCE III spectrometer (400 MHz,
100 MHz and 162 MHz, respectively), Chemical shifts are reported parts
per million (ppm) referenced to CDCl3 (δ 7.26 ppm), tetramethylsilane
(TMS, δ 0.00 ppm), for 1H NMR; CDCl3 (δ 77.16 ppm) or CD3OD (δ 49.00
ppm) for 13C NMR. High-resolution mass spectra (HRMS) were obtained
on an LTQ Orbitrap XL mass spectrometry equipped with an ESI source
from Thermo Scientific at Keeclound Biotech in Shanghai. X-ray
diffraction study for product 3aa was carried out on Bruker D8 VENTURE
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photon II diffractometer with Iµs 3.0 microfocus X-ray source using APEX
III program.
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General procedure for synthesis of products
：
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To an oven-dried 50 mL Schlenk sealed tube (with a Teflon cap)
equipped with a magnetic stir bar was added the phosphine 2 (0.20 mmol,
1.0 equiv), KF (18 mg, 0.3 mmol, 1.5 equiv) and 18-crown-6 (80 mg, 0.3
mmol, 1.5 equiv). Then the tube was evacuated under vacuum and charged
with CO2 (1 atm, 3 times). The reaction mixture was dissolved in
anhydrous THF (2.0 mL) under protection of CO2 atmosphere and
subsequently cooled the reaction mixture to 0 °C with stirring. At this
moment, aryne precursor 1 (0.24 mmol, 1.2 equiv) was added in the stirring
solution under protection of CO2 atmosphere. After the mixture was
reacted at 0 °C for 0.5 h, then taking out of the ice-bath, kept stirring at
o
room temperature or 40 C in oil bath until completion of the reaction
which was detected by TLC. The reaction mixture was then diluted with
40 mL dichloromethane and washed with saturated potassium sulfate
solution for 12 times (note: in order to remove completely the potassium
salt generated from KF with 18-C-6 which has closed polarity with
3). The residue was successively dried with anhydrous sodium sulfate,
filtered and evaporated of solvent to give the crude product. The crude
product was purified by column chromatography on silica gel (200-300
mesh, DCM:MeOH = 20:1 as eluent) to afford the corresponding
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phosphonium inner-salts 3 in moderate to excellent yields.
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Procedure for gram-scale synthesis of 3aa： To a 150 mL Schlenk sealed
tube with a magnetic stir bar was added the triphenylphosphine 2a (1.05 g,
4.0 mmol, 1.0 equiv), KF (0.348 g, 6.0 mmol, 1.5 equiv) and 18-crown-6
(1.585 g, 6.0 mmol, 1.5 equiv). Then the tube was evacuated under vacuum
and charged with CO2 (1 atm, 3 times). The reaction mixture was dissolved
in anhydrous THF (40 mL) under protection of CO2 atmosphere and
subsequently cooled the reaction mixture to 0 °C with stirring. At this
moment, benzyne precursor 1a (1.43 g, 4.8 mmol, 1.2 equiv) was added in
the stirring solution under protection of CO2 atmosphere. After the mixture
was reacted at 0 °C for 0.5 h, then taking out of the ice-bath, kept stirring
for 21 h at room temperature until completion of the reaction which was
detected by TLC. The reaction mixture was then diluted with 120 mL
dichloromethane and washed with saturated potassium sulfate solution for
12 times. The residue was successively dried with anhydrous sodium
sulfate, filtered and evaporated of solvent to give the crude product. The
crude product was purified by column chromatography on silica gel (200-
300 mesh, DCM:MeOH = 20:1 as eluent) to afford the clean o-
triphenylphosphonium benzoate 3aa in 1.42 g and 93% isolated yield.
Procedure for the reaction of benzene with CO2: To an oven-dried 50
mL Schlenk sealed tube (with a Teflon cap) equipped with a magnetic stir
bar was added KF (52 mg, 0.9 mmol, 3.0 equiv), 18-crown-6 (238 mg, 0.9
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mmol, 3.0 equiv). Then the tube was evacuated under vacuum and charged
with CO2 (1 atm, 3 times). The reaction mixture was dissolved in
anhydrous THF (3.0 mL) and subsequently aryne precursor 1a (89.4, 0.3
mmol, 1.0 equiv) was added to the stirring solution under the protection of
CO2 atmosphere, kept stirring at room temperature for 48 hours. Then, the
solvent was evaporated to give the crude product which was purified by
flash silica gel chromatography (PE : EA = 15:1) to afford pure 4a (10.6
mg, 18% yield).
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2-(triphenylphosphonio)benzoate (3aa) (known compound)22: purified
by flash silica gel chromatography ( DCM : MeOH = 20:1); white solid
(69.5 mg, 91%); m.p.: 233-234 oC; 1H NMR (400 MHz, CDCl3) δ 8.53 (dd,
J = 7.2, 3.6 Hz, 1H), 7.82 (t, J = 6.4 Hz, 1H), 7.57-7.33 (m, 16H), 6.99 (dd,
J = 13.6, 7.6 Hz, 1H).; 13C{1H} NMR (100 Hz, CDCl3) δ 166.2 , 143.9 (d,
J = 9.1 Hz), 136.5 (d, J = 14.8 Hz), 134.9 (d, J = 3.1 Hz), 132.4 (d, J = 9.1
Hz), 131.4 (d, J = 2.9 Hz), 130.8 (d, J = 14.8 Hz), 130.2 (d, J = 10.8 Hz),
128.7, 128.6, 122.3 (d, J = 113.0 Hz); 31P{1H} NMR (162 MHz, CDCl3) δ
6.44; HRMS (ESI) m/z: [M+H]+ Calcd for C25H20O2P 383.1195, Found
383.1194; IR (KBr, thin film): 3059, 1649, 1628, 1483, 1437, 1354, 1301,
1269, 831, 754, 731, 698 cm-1.
2-(tri-p-tolylphosphonio)benzoate (3ab): purified by flash silica gel
chromatography ( DCM : MeOH = 20:1); white solid (75.5 mg, 89%); m.p.:
o
159-160 C; 1H NMR (400 Hz, CDCl3) δ 8.49 (dd, J = 6.8, 4.4 Hz, 1H),
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7.66 (t, J = 5.6 Hz, 1H), 7.55-7.47 (m, 1H), 7.28-7.14 (m, 12H), 7.02 (dd,
J = 14.0, 7.6 Hz, 1H), 2.33 (s, 9H);13C{1H} NMR (100 Hz, CDCl3) δ 166.1 ,
144.1 (d, J = 3.0 Hz), 137.1 (d, J = 12.6 Hz), 135.1 (d, J = 2.9 Hz), 133.6
(d, J = 10.3 Hz), 133.2 (d, J = 10.1 Hz), 132.8 (d, J = 8.8 Hz), 130.9 (d, J
= 13.4 Hz), 130.1 (d, J = 13.4 Hz), 120.4 (d, J = 98.6 Hz), 119.9 (d, J =
95.9 Hz), 21.7 (d, J = 1.3 Hz); 31P{1H} NMR (162 MHz, CDCl3) δ 10.53;
HRMS (ESI) m/z: [M+H]+ Calcd for C28H26O2P 425.1665, Found 425.1664;
IR (KBr, thin film): 3024, 2926, 2866, 1645, 1622, 1564, 1501, 1397, 1379,
1273, 804, 760, 731, 691, 670 cm-1.
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2-(tris(4-methoxyphenyl)phosphonio)benzoate (3ac): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (86.9 mg,
92%); m.p.: 134-135 oC; 1H NMR (400 Hz, CDCl3) δ 8.56 (dd, J = 6.8, 4.0
Hz, 1H), 7.78 (t, J = 7.6 Hz, 1H), 7.51-7.43 (m, 1H), 7.39-7.30 (m, 6H),
13
7.00 (dd, J = 14.0, 7.6 Hz, 1H), 6.96-6.89 (m, 6H), 3.82 (s, 9H); C{1H}
NMR (100 Hz, CDCl3) δ 166.3 , 162.0 (d, J = 2.9 Hz), 144.7 (d, J = 8.5
Hz), 136.1 (d, J = 14.8 Hz), 134.6 (d, J = 11.0 Hz), 134.5, 130.9 (d, J =
10.4 Hz), 130.1 (d, J = 14.6 Hz), 122.0 (d, J = 109.1 Hz), 119.5 (d, J =
107.6 Hz), 114.3 (d, J = 14.2 Hz), 55.4; 31P{1H} NMR (162 MHz, CDCl3)
δ 21.16; HRMS (ESI) m/z: [M+H]+ Calcd for C28H26O5P 473.1512, Found
473.1513; IR (KBr, thin film): 3059, 2932, 2839, 1639, 1595, 1568, 1502,
1458, 1259, 829, 733, 690 cm-1.
2-(tris(4-fluorophenyl)phosphonio)benzoate (3ad): purified by flash
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silica gel chromatography ( DCM : MeOH = 20:1); white solid (82.0 mg,
94%); m.p.: 128-129 oC;1H NMR (400 Hz, CDCl3) δ 8.48 (dd, J = 7.2, 4.4
Hz, 1H), 7.91 (td, J = 7.6, 1.2 Hz, 1H), 7.69-7.63 (m, 1H), 7.49-7.36 (m,
6H), 7.27-7.12 (m, 6H), 7.06 (dd, J = 14.8, 8.0 Hz, 1H).; 13C{1H} NMR
(100 Hz, CDCl3) δ 166.2, 164.8 (dd, J = 255.0, 3.3 Hz), 141.3 (d, J = 7.9
Hz), 136.8 (d, J = 14.0 Hz), 135.7 (d, J = 2.9 Hz), 135.3 (t, J = 9.4 Hz),
132.1 (d, J = 14.5 Hz), 131.5 (d, J = 10.2 Hz), 122.6 (d, J = 104.6 Hz),
120.6 (d, J = 107.2 Hz), 116.8 (dd, J = 21.8, 14.6 Hz); 31P{1H} NMR (162
MHz, CDCl3) δ -0.47; HRMS (ESI) m/z: [M+H]+ Calcd for C25H17F3O2P
437.0913, Found 437.0916; IR (KBr, thin film): 3065, 1673, 1584, 1456,
1396, 1334, 1308, 835, 782, 727, 689 cm-1.
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2-(tris(4-(trifluoromethyl)phenyl)phosphonio)benzoate (3ae): purified
by flash silica gel chromatography ( DCM : MeOH = 20:1); white solid
(112.5 mg, 96%); m.p.: 97-98 oC; 1H NMR (400 Hz, CDCl3) δ 8.50 (dd, J
= 7.6, 3.2 Hz, 1H), 7.96 (td, J = 7.6, 1.2 Hz, 1H), 7.85-7.20 (m, 13H), 7.00
(dd, J = 12.8, 7.6 Hz, 1H).;13C{1H} NMR (100 Hz, CDCl3) δ 165.4 , 142.5
(d, J = 11.8 Hz), 136.6 (d, J = 15.0 Hz), 135.9 (d, J = 3.3 Hz), 133.0 (qd, J
= 33.0, 2.9 Hz), 132.2 (d, J = 15.5 Hz), 129.3 (d, J = 12.5 Hz), 125.8 (d, J
= 1.7 Hz), 125.6 (d, J = 2.9 Hz), 124.5 (d, J = 124.4 Hz), 123.2 (q, J =
271.1 Hz); 31P{1H} NMR (162 MHz, CDCl3) δ -21.57; HRMS (ESI) m/z:
[M+H]+ Calcd for C28H17F9O2P 587.0817, Found 587.0811; IR (KBr, thin
film): 3070, 1680, 1611, 1400, 1325, 1173, 1130, 1064, 1016, 835, 715,
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692 cm-1.
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2-(tri-m-tolylphosphonio)benzoate (3af): purified by flash silica gel
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chromatography ( DCM : MeOH = 20:1); white solid (73.8 mg, 87%); m.p.:
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164-165 C; H NMR (400 Hz, CDCl3) δ 8.55 (dd, J = 7.6, 4.0 Hz, 1H),
7.82 (t, J = 7.2 Hz, 1H), 7.58-7.44 (m, 1H), 7.35-7.27 (m, 7H), 7.23-7.14
(m, 5H), 6.97 (dd, J = 13.6, 8.0 Hz, 1H), 2.31 (s, 9H); 13C{1H} NMR (100
Hz, CDCl3) δ 166.1 , 144.3 (d, J = 8.9 Hz), 138.4 (d, J = 12.8 Hz), 136.4
(d, J = 14.7 Hz), 134.6 (d, J = 3.2 Hz), 132.8 (d, J = 9.1 Hz), 132.1 (d, J =
2.9 Hz), 130.5 (d, J = 14.7 Hz), 130.3 (d, J = 10.7 Hz), 129.7 (d, J = 9.5
Hz), 128.4, 128.3, 122.5 (d, J = 112.3 Hz), 21.6; 31P{1H} NMR (162 MHz,
CDCl3) δ 8.78; HRMS (ESI) m/z: [M+H]+ Calcd for C28H26O2P 425.1665,
Found 425.1665; IR (KBr, thin film): 3026, 2923, 2867, 1645, 1623, 1564,
1500, 1394, 1381, 1276, 803, 760, 732, 692, 670 cm-1.
2-(tris(3-methoxyphenyl)phosphonio)benzoate (3ag): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (89.7 mg,
95%); m.p.: 93-94 C; 1H NMR (400 Hz, CDCl3) δ 8.51 (dd, J = 7.2, 4.0
o
Hz, 1H), 7.83 (td, J = 7.6, 1.2 Hz, 1H), 7.57-7.48 (m, 1H), 7.36-7.29 (m,
3H), 7.07-6.36 (m, 10H), 3.71 (s, 9H); 13C{1H} NMR (100 Hz, CDCl3) δ
166.1 , 159.3 (d, J = 16.6 Hz), 143.9 (d, J = 9.4 Hz), 136.5 (d, J = 14.8 Hz),
134.9 (d, J = 3.1 Hz), 130.7 (d, J = 14.8 Hz), 129.9 (d, J = 11.1 Hz), 129.8,
129.6, 124.5 (d, J = 6.0 Hz), 122.7 (d, J = 115.1 Hz), 118.4 (d, J = 10.2 Hz),
116.3 (d, J = 2.7 Hz), 55.4; P{1H} NMR (162 MHz, CDCl3) δ 3.13;
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HRMS (ESI) m/z: [M+H]+ Calcd for C28H26O5P 473.1512, found 473.1511;
IR (KBr, thin film): 3058, 2928, 2837, 1636, 1596, 1567, 1502, 1456, 1260,
828, 732, 691 cm-1.
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2-(tris(3,5-dimethylphenyl)phosphonio)benzoate (3ah): purified by
flash silica gel chromatography ( DCM : MeOH = 20:1); white solid (83.9
mg, 90%); m.p.: 95-96 oC; 1H NMR (400 Hz, CDCl3) δ 8.55 (dd, J = 6.8,
4.0 Hz, 1H), 7.73 (t, J = 7.2 Hz, 1H), 7.54-7.45 (m, 1H), 7.14 (s, 3H), 7.06-
6.90 (m, 7H), 2.26 (s, 18H); 13C{1H} NMR (100 Hz, CDCl3) δ 166.4 , 138.3
(d, J = 13.7 Hz), 136.6 (d, J = 14.0 Hz), 134.5 (d, J = 2.9 Hz), 133.7 (d, J
= 2.3 Hz), 131.1 (d, J = 10.0 Hz), 130.7 (d, J = 14.3 Hz), 130.3 (d, J = 9.3
Hz), 127.3 (d, J = 97.8 Hz), 121.4 (d, J = 105.7 Hz), 21.5; 31P{1H} NMR
(162 MHz, CDCl3) δ 13.11; HRMS (ESI) m/z: [M+H]+ Calcd for
C31H32O2P 467.2134, Found 467.2138; IR (KBr, thin film): 3028, 2926,
2858, 1655, 1564, 1454, 1393, 1271, 847, 760, 689 cm-1.
2-(tris(3-chlorophenyl)phosphonio)benzoate (3ai): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (81.3 mg;
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84%); m.p.: 93-94 C; 1H NMR (400 Hz, CDCl3) δ 8.48 (dd, J = 7.2, 3.2
Hz, 1H), 7.91 (td, J = 7.6, 1.2 Hz, 1H), 7.67-7.59 (m, 1H), 7.56-7.05 (m,
12H), 6.90 (dd, J = 13.2, 8.0 Hz, 1H); 13C{1H} NMR (100 Hz, CDCl3) δ
165.6 , 142.8 (d, J = 11.3 Hz), 136.6 (d, J = 15.1 Hz), 135.6 (d, J = 3.3 Hz),
135.2, 134.9, 131.9 (d, J = 15.4 Hz), 131.48, 131.46, 130.1 , 130.0 , 129.3
(d, J = 12.2 Hz), 124.1 (d, J = 122.7 Hz); 31P{1H} NMR (162 MHz, CDCl3)
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δ -15.94; HRMS (ESI) m/z: [M+H]+ Calcd for C25H17Cl3O2P 485.0026,
Found 485.0030; IR (KBr, thin film): 3063, 1663, 1564, 1468, 1398, 1340,
1300, 835, 777, 725, 685 cm-1.
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2-(tri-o-tolylphosphonio)benzoate (3aj): purified by flash silica gel
chromatography ( DCM : MeOH = 20:1); white solid (55.1 mg, 65%); m.p.:
83-84 oC; 1H NMR (400 Hz, CDCl3) δ 8.64 (dd, J = 6.8, 4.4 Hz, 1H), 7.92-
7.73 (m, 4H), 7.61-7.48 (m, 5H), 7.45-7.39 (m, 2H), 7.36 (t, J = 7.2 Hz,
1H), 7.23 (d, J = 7.2 Hz, 1H), 7.17 (q, J = 6.8 Hz, 2H), 1.78 (s, 3H), 1.75
(s, 3H), 1.62 (s, 3H); 13C{1H} NMR (100 Hz, CDCl3) δ 165.7, 145.5 (d, J
= 7.9 Hz), 143.4 (d, J = 6.3 Hz), 140.9 (d, J = 11.5 Hz), 138.7 (d, J = 9.3
Hz), 138.6 (d, J = 10.2 Hz), 136.2 (d, J = 10.9 Hz), 135.8 (d, J = 9.7 Hz),
135.5 (d, J = 15.6 Hz), 134.6 (d, J = 3.1 Hz), 134.4 (d, J = 10.8 Hz), 133.3
(d, J = 8.6 Hz), 132.6 (d, J = 2.2 Hz), 132.3, 132.2 (d, J = 16.5 Hz), 131.9
(d, J = 13.0 Hz), 131.7 (d, J = 3.7 Hz), 131.6 (d, J = 3.2 Hz), 130.4 (d, J =
14.7 Hz), 126.8 (d, J = 9.9 Hz), 126.2 (d, J = 14.6 Hz), 126.0 (d, J = 13.9
Hz), 124.4 (d, J = 111.0 Hz), 122.2 (d, J = 108.3 Hz), 120.5 (d, J = 101.0
Hz), 23.0 (d, J = 3.3 Hz), 22.8 (d, J = 2.2 Hz), 22.7 (d, J = 4.4 Hz); 31P{1H}
NMR (162 MHz, CDCl3) δ 21.76; HRMS (ESI) m/z: [M+H]+ Calcd for
C28H26O2P 425.1665, Found 425.1661; IR (KBr, thin film): 3061, 2932,
2864, 1726, 1593, 1564, 1474, 1448, 1271, 1223, 806, 760, 721, 692 cm-1.
2-([1,1'-biphenyl]-2-yldiphenylphosphonio)benzoate (3al): purified by
flash silica gel chromatography ( DCM : MeOH = 20:1); white solid (77.0
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mg, 84%); m.p.: 298-299 C; 1H NMR (400 Hz, CDCl3) δ 8.23 (s, 1H),
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δ 167.2 , 145.3 (d, J = 8.4 Hz), 140.1, 138.7 (d, J = 4.5 Hz), 135.8 (d, J =
13.3 Hz), 134.2, 134.1, 132.9 (d, J = 12.0 Hz), 132.4 (d, J = 11.0 Hz), 132.1,
131.5, 131.3, 131.2 (d, J = 10.1 Hz), 129.7, 128.7, 128.6, 127.7, 127.6,
127.3, 124.1 (d, J = 95.6 Hz), 122.9 (d, J = 85.4 Hz); 31P{1H} NMR (162
MHz, CDCl3) δ 4.24; HRMS (ESI) m/z: [M+H]+ Calcd for C31H24O2P
459.1508, Found 459.1510; IR (KBr, thin film): 3057, 1641, 1568, 1433,
1344, 1301, 1253, 831, 750, 729, 697 cm-1.
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2-(tri(naphthalen-1-yl)phosphonio)benzoate (3am): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (42.6 mg,
40%); m.p.: 110-111oC; 1H NMR (400 Hz, CDCl3) δ 8.63 (dd, J = 6.8, 5.2
Hz, 1H), 8.48 (dd, J = 19.6, 7.6 Hz, 1H), 8.33 (dd, J = 19.2, 7.2 Hz, 1H),
8.08 (d, J = 8.0 Hz, 1H), 8.05-7.92 (m, 4H), 7.86-7.79 (m, 2H), 7.71 (d, J
= 8.0 Hz, 2H), 7.63 (td, J = 8.0, 2.8 Hz, 1H), 7.53-7.40 (m, 5H), 7.36-7.30
(m, 2H), 7.24-7.16 (m, 2H), 7.12 (t, J = 7.2 Hz, 1H), 6.95-6.86 (m, 2H);
13C{1H} NMR (100 Hz, CDCl3) δ 165.8, 139.8 (d, J = 9.8 Hz), 137.9 (d, J
= 10.2 Hz), 137.7 (d, J = 9.4 Hz), 136.3 (d, J = 16.2 Hz), 134.9 (d, J = 3.0
Hz), 134.5 (d, J = 2.5 Hz), 134.3 (d, J = 3.7 Hz), 133.9 (d, J = 14.5 Hz),
133.8 (d, J = 4.4 Hz), 133.7 (d, J = 4.7 Hz), 133.3 (d, J = 3.0 Hz), 132.7 (d,
J = 11.2 Hz), 132.2 (d, J = 5.0 Hz), 132.1 (d, J = 4.1 Hz), 130.4 (d, J = 4.9
Hz), 129.9 (d, J = 2.1 Hz), 129.7 (d, J = 1.9 Hz), 129.5, 127.3, 126.8, 126.4,
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J = 4.6 Hz), 125.3 (d, J = 5.3 Hz), 125.1 (d, J = 4.6 Hz), 124.8 (d, J = 11.9
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Hz), 121.6 (d, J = 100.3 Hz); P{1H} NMR (162 MHz, CDCl3) δ 22.59;
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HRMS (ESI) m/z: [M+H]+ Calcd for C37H26O2P 533.1665, found 533.1663;
IR (KBr, thin film): 3059, 1726, 1506, 1460, 1275, 833, 802, 773, 692, 675
cm-1.
2-(tri(thiophen-2-yl)phosphonio)benzoate (3an): purified by flash silica
gel chromatography ( DCM : MeOH = 20:1); white solid (56.8 mg, 71%);
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m.p.: 217-218 C; 1H NMR (400 Hz, CDCl3) δ 8.37 (dd, J = 7.6, 2.8 Hz,
1H), 7.80 (td, J = 7.2, 2.4 Hz, 1H), 7.66 (td, J = 4.8, 0.8 Hz, 3H), 7.54 (q,
J = 7.6 Hz, 1H), 7.37 (d, J = 4.2 Hz, 3H), 7.17-7.08 (m, 3H), 6.96 (dd, J =
14.4, 8.0 Hz, 1H); 13C{1H} NMR (100 Hz, CDCl3) δ 165.7 (d, J = 2.4 Hz),
139.9 (d, J = 14.2 Hz), 137.7 (d, J = 12.1 Hz), 135.6 (d, J = 16.0 Hz), 135.0
(d, J = 3.6 Hz), 133.3 , 131.8 (d, J = 16.6 Hz), 131.5 (d, J = 138.7 Hz),
128.0 (d, J = 14.0 Hz), 127.3, 127.2; 31P{1H} NMR (162 MHz, CDCl3) δ -
53.25; HRMS (ESI) m/z: [M+H]+ Calcd for C19H14O2PS3 400.9888, Found
400.9889; IR (KBr, thin film): 3112, 1670, 1459, 1340, 1296, 1220, 1138,
1065, 842, 763, 735, 692 cm-1.
2-(tri(furan-2-yl)phosphonio)benzoate (3ao): purified by preparative
thin layer chromatography ( DCM : MeOH = 20:1); white solid (14.1 mg,
20%); m.p.: 167-168 oC;1H NMR (400 Hz, CDCl3) δ 8.26 (dd, J = 7.6, 3.2
Hz, 1H), 7.76 (tdd, J = 7.2, 2.4, 0.8 Hz, 1H), 7.70-7.63 (m, 3H), 7.58-7.51
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(m, 1H), 7.03 (br s, 3H), 6.66 (dd, J = 14.4, 8.0 Hz, 1H), 6.55-6.50 (m,
3H).; 13C{1H} NMR (100 Hz, CDCl3) δ 166.0 (d, J = 4.0 Hz), 147.2 (d, J
= 9.0 Hz), 138.3 (d, J = 15.2 Hz), 134.7 (d, J = 3.5 Hz), 134.1 (d, J = 15.2
Hz), 132.9 (d, J = 145.8 Hz), 132.5 (d, J = 16.9 Hz), 127.0 (d, J = 14.9 Hz),
124.8 (d, J = 17.5 Hz), 111.3, 111.2; 31P{1H} NMR (162 MHz, CDCl3) δ -
90.75; HRMS (ESI) m/z: [M+H]+ Calcd for C19H14O5P 353.0573, Found
353.0573; IR (KBr, thin film): 3115, 1698, 1454, 1337, 1296, 1215, 1134,
1064, 843, 760, 731, 687 cm-1.
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2-(methyldiphenylphosphonio)benzoate (3ap): purified by flash silica
gel chromatography ( DCM : MeOH = 20:1); white solid (43.5 mg, 68%);
o
m.p.: 254-255 C; 1H NMR (400 Hz, CDCl3) δ 8.47 (dd, J = 6.8, 4.0 Hz,
1H), 7.76 (t, J = 7.2 Hz, 1H), 7.60-7.30 (m, 11H), 6.85 (dd, J = 14.0, 7.6
Hz, 1H), 2.83 (d, J = 13.6 Hz, 3H); 13C{1H} NMR (100 Hz, CDCl3) δ
167.1(d, J = 1.0 Hz), 139.7 (d, J = 5.8 Hz), 136.5 (d, J = 13.2 Hz), 135.1
(d, J = 2.9 Hz), 133.0 (d, J = 2.6 Hz), 132.2 (d, J = 9.3 Hz), 131.8 (d, J =
9.6 Hz), 131.7 (d, J = 13.8 Hz), 129.7 (d, J = 12.5 Hz), 125.4 (d, J = 91.7
Hz), 120.9 (d, J = 96.6 Hz), 13.7 (d, J = 69.6 Hz); 31P{1H} NMR (162 MHz,
CDCl3) δ 5.17; HRMS (ESI) m/z: [M+H]+ Calcd for C20H18O2P 321.1039,
Found 321.1040; IR (KBr, thin film): 3052, 2958, 2875, 1648, 1624, 1485,
1437, 1355, 1302, 1269, 830, 753, 730, 695 cm-1.
2-(dimethyl(phenyl)phosphonio)benzoate (3aq): purified by preparative
thin layer chromatography (DCM : MeOH = 15 : 1); white solid (33.0 mg,
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64%); m.p.:174-175℃; 1H NMR (400 MHz, CDCl3) δ 8.41 (ddd, J = 7.6,
4.4, 1.2 Hz, 1H), 7.81-7.75 (m, 1H), 7.62-7.42 (m, 7H), 2.32 (s, 3H), 2.29
(s, 3H); 13C{1H} NMR (100 MHz, CDCl3) δ 166.8, 142.6 (d, J = 8.9 Hz),
134.7 (d, J = 3.2 Hz), 133.0 (d, J = 14.5 Hz), 131.4 (d, J = 3.0 Hz), 130.5
(d, J = 105.0 Hz), 130.5 (d, J = 10.6 Hz), 130.4 (d, J = 14.5 Hz), 129.1 (d,
J = 13.2 Hz), 128.9 (d, J = 10.0 Hz), 123.6 (d, J = 109.2 Hz), 16.9, 16.2.
31P{H} NMR (162 MHz, CDCl3) δ 1.34; HRMS (ESI) m/z: [M+Na]+ Calcd
for C15H15O2PNa 281.0702, found 281.0700; IR (KBr, thin film): 3057,
2978, 2912, 1622, 1566, 1442, 1364, 1124, 887, 830, 760, 735, 718, 693
cm-1.
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2-(tricyclohexylphosphonio)benzoate (3ar): purified by preparative thin
layer chromatography (DCM : MeOH = 20 : 1); white solid (12.0 mg, 15%);
m.p.:275-276℃; 1H NMR (400 MHz, CDCl3) δ 8.39 (dd, J = 8.0, 4.4 Hz,
1H), 7.65 (t, J = 7.6 Hz, 1H), 7.59-7.46 (m, 2H), 3.29 (q, J = 12.8 Hz, 3H),
2.01 (br s, 6H), 1.92-1.59 (m, 16H), 1.50-1.30 (m, 8H); 13C{1H} NMR (100
MHz, CDCl3) δ 169.3 , 133.3, 133.2, 132.6 (d, J = 9.1 Hz), 132.3 (d, J =
7.9 Hz), 128.9 (d, J = 10.7 Hz), 116.2 (d, J = 78.6 Hz), 36.1 (d, J = 43.1
31
Hz), 28.5, 28.4, 27.1, 26.9, 25.7; P NMR (162 MHz, CDCl3) δ 31.61;
HRMS (ESI) m/z: [M+H]+ Calcd for C25H38O2P 401.2609, Found 401.2607;
IR (KBr, thin film): 3057, 2830, 2854, 1618, 1585, 1449, 1362 , 1271, 895,
852, 825, 754, 731, 696 cm-1.
2-(triphenylarsonio)benzoate (3as): purified by flash silica gel
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chromatography ( DCM : MeOH = 20:1); white solid (75.0 mg, 88%); m.p.:
187-188 oC; 1H NMR (400 Hz, CDCl3) δ 8.59 (d, J = 7.6 Hz, 1H), 7.79 (t,
J = 7.6 Hz, 1H), 7.57-7.35 (m, 16H), 7.03 (d, J = 7.6 Hz, 1H); 13C{1H}
NMR (100 Hz, CDCl3) δ 166.4, 141.8, 133.9, 133.3, 132.2, 131.4, 131.1,
130.6, 129.3, 125.5; HRMS (ESI) m/z: [M+H]+ Calcd for C25H20AsO2
427.0674, Found 427.0672; IR (KBr, thin film): 3058, 1639, 1622, 1564,
1483, 1348, 1271, 827, 766, 745, 689 cm-1.
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4,5-dimethyl-2-(triphenylphosphonio)benzoate (3ba): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (68.9 mg;
84%); m.p.: 144-145 oC; 1H NMR (400 Hz, CDCl3) δ 8.30 (d, J = 4.4 Hz,
1H), 7.58-7.35 (m, 15H), 6.68 (d, J = 13.6 Hz, 1H), 2.42 (s, 3H), 2.18 (s,
3H); 13C{1H} NMR (100 Hz, CDCl3) δ 166.6 , 144.9 (d, J = 3.2 Hz), 141.3
(d, J = 7.5 Hz), 140.0 (d, J = 14.9 Hz), 137.6 (d, J = 14.6 Hz), 132.5 (d, J
= 9.1 Hz), 131.8 (d, J = 11.5 Hz), 131.5 (d, J = 2.6 Hz), 128.7, 128.6, 118.4
31
(d, J = 113.0 Hz), 20.2, 19.9 (d, J = 1.1 Hz); P{1H} NMR (162 MHz,
CDCl3) δ 6.18; HRMS (ESI) m/z: [M+H]+ Calcd for C27H24O2P 411.1508,
Found 411.1509; IR (KBr, thin film): 3054, 2928, 2862, 1666, 1480, 1438,
1333, 1270, 843, 778, 725, 695, 680 cm-1.
4,5-dimethoxy-2-(triphenylphosphonio)benzoate (3ca): purified by
flash silica gel chromatography ( DCM : MeOH = 20:1); white solid (52.2
mg, 59%); m.p.: 276-277 oC; 1H NMR (400 Hz, CDCl3) δ 8.04 (d, J = 4.0
Hz, 1H), 7.56-7.33 (m, 15H), 6.26 (d, J = 14.0 Hz, 1H), 4.06 (s, 3H), 3.48
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(s, 3H);13C{1H} NMR (100 Hz, CDCl3) δ 166.2 , 154.2 , 150.7 (d, J = 18.7
Hz), 139.1 (d, J = 10.1 Hz), 132.4 , 131.2 (d, J = 2.9 Hz), 128.6, 128.5,
117.8 (d, J = 8.6 Hz), 113.1 (d, J = 123.2 Hz), 112.0 (d, J = 14.4 Hz), 56.6,
55.6; 31P{1H} NMR (162 MHz, CDCl3) δ 0.80; HRMS (ESI) m/z: [M+H]+
Calcd for C27H24O4P 443.1407, Found 443.1407; IR (KBr, thin film): 3061,
2935, 2839, 1644, 1584, 1503, 1439, 1393, 1335, 1283, 1245, 1215, 800,
777, 731, 703, 694 cm-1.
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4,5-difluoro-2-(triphenylphosphonio)benzoate (3da): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (74.4 mg,
89%); m.p.: 263-264 oC; 1H NMR (400 Hz, CDCl3) δ 8.37-8.27 (m, 1H),
7.61-7.32 (m, 15H), 6.70-6.30 (m, 1H); 13C{1H} NMR (100 Hz, CDCl3) δ
164.2 , 154.7 (ddd, J = 260.6, 12.9, 3.3 Hz), 152.0 (ddd, J = 253.3, 22.3,
3.3 Hz), 142.7 (dd, J = 5.7, 2.7 Hz), 142.6 (dd, J = 5.7, 2.8 Hz), 132.3 (d,
J = 7.7 Hz), 131.8 (d, J = 2.9 Hz), 128.9 (d, J = 13.2 Hz), 125.3 (t, J = 19.4
Hz), 119.3 (dt, J = 119.3, 3.3 Hz), 119.2 (dd, J = 17.3, 14.2 Hz); 31P{1H}
NMR (162 MHz, CDCl3) δ 3.63; HRMS (ESI) m/z: [M+H]+ Calcd for
C25H18F2O2P 419.1007, Found 419.1008; IR (KBr, thin film): 3029, 1651,
1608, 1495, 1485, 1439, 1407, 1340, 1290, 1184, 1115, 1101, 783, 756,
733, 705, 692 cm-1.
6-(triphenylphosphonio)-2,3-dihydro-1H-indene-5-carboxylate (3ea):
purified by flash silica gel chromatography ( DCM : MeOH = 20:1); white
solid (76.0 mg, 90%); m.p.: 189-190 oC; 1H NMR (400 Hz, CDCl3) δ 8.37
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(d, J = 3.6 Hz, 1H), 7.55-7.31 (m, 15H), 6.75 (d, J = 13.6 Hz, 1H), 3.06 (t,
J = 7.6 Hz, 2H), 2.83 (t, J = 7.6 Hz, 2H), 2.20-2.10 (m, 2H);13C{1H} NMR
(100 Hz, CDCl3) δ 166.6 , 152.8 (d, J = 3.2 Hz), 147.8 (d, J = 15.7 Hz),
142.8 (d, J = 10.3 Hz), 132.3 (d, J = 6.3 Hz), 131.9 (d, J = 14.5 Hz), 130.9
(d, J = 2.8 Hz), 128.5, 128.4, 125.9 (d, J = 12.5 Hz), 120.5 (d, J = 115.9
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Hz), 32.83 (d, J = 10.4 Hz), 32.81 (d, J = 10.3 Hz), 25.5; P{1H} NMR
(162 MHz, CDCl3) δ 0.95; HRMS (ESI) m/z: [M+H]+ Calcd for C28H24O2P
423.1508, Found 423.1509; IR (KBr, thin film): 3057, 2957, 2937, 2843,
1645, 1628, 1557, 1439, 1404, 1337, 1275, 806, 752, 729, 710, 694 cm-1.
6-(triphenylphosphonio)benzo[d][1,3]dioxole-5-carboxylate
(3fa):
purified by flash silica gel chromatography ( DCM : MeOH = 20:1); white
solid (75.8 mg, 89%); m.p.: 258-259 oC; 1H NMR (400 Hz, CDCl3) δ 7.90
(s, 1H), 7.61-7.28 (m, 15H), 6.28 (d, J = 12.8 Hz, 1H), 6.14 (s, 2H);13C{1H}
NMR (100 Hz, CDCl3) δ 153.5 (d, J = 3.0 Hz), 150.8, 150.5, 132.4, 131.4
(d, J = 2.7 Hz), 128.7, 128.6, 115.0, 114.9, 110.4 (d, J = 13.3 Hz), 103.1;
31P{1H} NMR (162 MHz, CDCl3) δ -2.40; HRMS (ESI) m/z: [M+H]+
Calcd for C26H20O4P 427.1094, Found 427.1096; IR (KBr, thin film): 3058,
2925, 2830, 1641, 1582, 1500, 1439, 1397, 1338, 1278, 1239, 1214, 787,
741, 694 cm-1.
3,6-dimethyl-2-(triphenylphosphonio)benzoate (3ga): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (41.8 mg,
51%); m.p.: 243-244 oC; 1H NMR (400 Hz, CDCl3) δ 7.61-7.36 (m, 16H),
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7.19 (t, J = 7.2 Hz, 1H), 2.75 (s, 3H), 1.69 (s, 3H); 13C{1H} NMR (100 Hz,
CDCl3) δ 167.9, 145.3 (d, J = 13.0 Hz), 141.6 (d, J = 12.3 Hz), 137.7 (d, J
= 12.3 Hz), 137.2 (d, J = 3.2 Hz), 134.0 (d, J = 14.9 Hz), 132.2 (d, J = 9.6
Hz), 131.1 (d, J = 2.8 Hz), 128.8, 128.7, 121.8 (d, J = 110.1 Hz), 23.9 (d,
J = 3.8 Hz), 21.1; 31P{1H} NMR (162 MHz, CDCl3) δ -13.8; HRMS (ESI)
m/z: [M+H]+ Calcd for C27H24O2P 411.1508, Found 411.1508; IR (KBr,
thin film): 3057, 2926, 2856, 1663, 1483, 1437, 1329, 1270, 841, 775, 725,
696, 679 cm-1.
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3-(triphenylphosphonio)-2-naphthoate (3ha): purified by flash silica gel
chromatography ( DCM : MeOH = 20:1); white solid (71.7 mg, 83%); m.p.:
247-248 oC; 1H NMR (400 Hz, CDCl3) δ 9.03 (d, J = 3.6 Hz, 1H), 8.10 (d,
J = 8.0 Hz, 1H), 7.76-7.34 (m, 19H); 13C{1H} NMR (100 Hz, CDCl3) δ
166.8 , 140.4 (d, J = 14.7 Hz), 137.4 (d, J = 9.5 Hz), 136.0 (d, J = 2.6 Hz),
133.3 (d, J = 16.4 Hz), 132.6 , 131.5 (d, J = 2.6 Hz), 130.5 (d, J = 10.5 Hz),
129.9 , 129.2 , 129.1 , 128.8, 128.6, 128.1 , 119.5 (d, J = 114.0 Hz); 31P{1H}
NMR (162 MHz, CDCl3) δ 5.72; HRMS (ESI) m/z: [M+H]+ Calcd for
C29H22O2P 433.1352, Found 433.1353; IR (KBr, thin film): 3059, 1719,
1586, 1473, 1407, 1325, 1272, 801, 770, 698 cm-1.
2-methoxy-6-(triphenylphosphonio)benzoate (3ia): purified by flash
silica gel chromatography ( DCM : MeOH = 20:1); white solid (43.7 mg,
53%); m.p.: 208-209 oC; 1H NMR (400 Hz, CDCl3) δ 7.43-7.32 (m, 17H),
6.51 (dd, J = 13.6, 8.0 Hz, 1H), 4.04 (s, 3H);13C{1H} NMR (100 Hz, CDCl3)
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