Wittig Olefination Using Phosphonium Tetraphenylborate in the Absence of Additional Base

Article abstract of DOI:10.1080/10426507.2014.902827

The thermal decomposition of (substituted methyl)triphenylphosphonium tetraphenylborates, which can also be generated in situ from the corresponding phosphonium halide and NaBPh₄, with an aldehyde affords olefins in 22-100% yields. This Wittig olefination does not need use additional base to form phosphorus ylide, and is highly tolerant of benzoic acid.

Full text of DOI:10.1080/10426507.2014.902827

This article was downloaded by: [RMIT University]
On: 07 September 2014, At: 05:32
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the Related
Elements
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Wittig Olefination Using Phosphonium
Tetraphenylborate in the Absence of Additional Base
Wenhua Huanga, Shuang-Hong Zhaoa & Guang-Ping Donga
a Department of Chemistry, Tianjin University, Tianjin 300072, P. R. China
Accepted author version posted online: 26 Jun 2014.
To cite this article: Wenhua Huang, Shuang-Hong Zhao & Guang-Ping Dong (2014): Wittig Olefination Using Phosphonium
Tetraphenylborate in the Absence of Additional Base, Phosphorus, Sulfur, and Silicon and the Related Elements, DOI:
10.1080/10426507.2014.902827
To link to this article: http://dx.doi.org/10.1080/10426507.2014.902827
Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service
to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting,
typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of
the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the
content, and all legal disclaimers that apply to the journal relate to this version also.
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

ACCEPTED MANUSCRIPT
Running Head: Wittig Olefination Using Phosphonium Tetraphenylborate
Wittig Olefination Using Phosphonium Tetraphenylborate in the Absence of Additional
Base
Wenhua Huang,* Shuang-Hong Zhao, and Guang-Ping Dong
Department of Chemistry, Tianjin University, Tianjin 300072, P. R. China
huangwh@tju.edu.cn
Abstract: The thermal decomposition of (substituted methyl)triphenylphosphonium
tetraphenylborates, which can also be generated in situ from the corresponding phosphonium
halide and NaBPh4, with an aldehyde affords olefins in 22-100% yields. This Wittig olefination
does not need use additional base to form phosphorus ylide, and is highly tolerant of benzoic
acid.
Keywords: Wittig olefination, phosphonium tetraphenylborate, thermal decomposition, sodium
tetraphenylborate, phosphonium halide, aldehyde
1
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Introduction
One of the most powerful reactions to form carbon-carbon double bonds in organic synthesis is
the Wittig olefination, in which a phosphorus ylide reacts with an aldehyde or a ketone to form
an olefin.[1] The phosphorus ylide can be generated by using a base to deprotonate a
phosphonium salt, as shown inScheme 1 (right). In the absence of a base, several phosphonium
salts, after thermal decomposition, have been reported to produce the phosphorus ylides, such as
Me3P=CH2 and Me3P=CHSiMe3 from Me3SiCH2P+Me3(Cl-),[2] and Ph3P=CH2 from triphenyl
phosphonium alkyl ester halides.[3]
Most of the phosphonium salts used in the Wittig olefination are phosphonium halides which are
usually prepared from triphenylphosphine and an alkyl halide. The tetraphenylboron anion has
often been used in anion-exchange reaction for converting a phosphonium halide into a
phosphonium tetraphenylborate in order to obtain a crystal salt for easy isolation,[4-5] increasing
the solubility and facilitating purification[6-7] or X-ray structural analysis[8-9] or elemental
analysis.[10-11] The obtained phosphonium tetraphenylborates have been shown to produce a
phosphonium ylide after treating with a base, and can thus also be used in the Wittig
olefination.[4,12-13] Herein, we report that the thermal decomposition of phosphonium
tetraphenylborate 1 with aldehyde 3 produced olefin 4 without the use of additional base, as
shown in Scheme 1 (left).
2
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Results and discussion
Phosphonium tetraphenylborate 1ab was conveniently prepared from the corresponding
phosphonium chloride 1aa and NaBPh4 by anion exchange in water at room temperature. It was
characterized by 1H-, 13C-, 31P-, and 11B-NMR, HRMS and elemental analysis. When an
equimolar mixture of 1ab and p-chlorobenzaldehyde 3a in toluene was heated in an oil bath (120
C) under nitrogen for 12 h, 4aa was obtained in 64% yield with a trans:cis ratio of 68:32 (Table
1, entry 1). By replacing toluene with CH3CN, the yield of 4aa increased to 92% at 120 C even
though the reaction was run for 6 h (entry 2). Screening other solvents showed that 4aa could be
obtained in a variety of solvents with the yields varying from 39% to 74% (entries 3-10). When
using other phosphonium tetraphenylborates, we found that 1bb gave the desired product 4ba in
69% yield, while 1cb gave 4ca in 61% yields after increasing reaction time to 12 h (entries 11
and 12). For phosphonium tetraphenylborate 1db and 1eb, however, no olefination product was
detected (entries 13 and 14), indicating that this reaction was limited to the phosphonium
tetraphenylborates that can form the stabilized phosphorus ylides. A control experiment using
phosphonium chloride 1aa under similar conditions gave 4aa in only 35% yield and with a 65:35
ratio of trans to cis (entry 15).
We found that directly heating a mixture of 1aa, NaBPh4, and 3a in acetonitrile could also
provide 4aa in 89% yield with a comparable trans: cis ratio (Table 2, entry 1) to that of the
reaction using 1ab, suggesting that 1ab could be generated in situ by anion-exchange. Because
3
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
this one-pot procedure simplified the operation, we applied it to examine a range of aldehydes, as
summarized in Table 2. Aromatic aldehydes with an electron-withdrawing group (Cl, Br, F, or
NO2), regardless of its position on the benzene ring, afforded the corresponding olefins 4aa-4af
in good to excellent yields (entries 1-6) but 4ag in a moderate yield (63%) (entry 7) .
Benzaldehyde 3h and 1-napththaldehyde 3i gave 4ah and 4ai in 75% and 80% yields,
respectively (entries 8 and 9). The olefination yields of aromatic aldehydes 3j-3o with one or two
electron-donating groups on the benzene ring were moderate except for 3o, which gave 4ao in a
quantitative yield (entries 10-15). The yields of 4j-4n could probably be improved by increasing
the reaction time; for example, the yield of 4l increased to 72% when the reaction time was
increased to 12 h (entry 12). The aliphatic aldehyde 3p gave 4ap in a low yield (entry 16). We
have also examined benzophenone (not shown in Table 2) but no olefin product was detected.
For other phosphonium halides, 1ba and 1cc gave 4ba and 4ca in 69% and 80% yields with
84:16 and 100:0 ratios of trans to cis, respectively, after the reactions were run for 12 h (entries
17 and 18).
An attractive feature of this thermal Wittig olefination is its compatibility with benzoic acid.
Although it has been reported that a catalytic amount of benzoic acid promoted the Wittig
reaction of the stabilized phosphonium ylide,[14-17] we found 1 equiv of benzoic acid almost
destroyed the ylide of 2a in refluxing CH3CN, leading to the formation of 4aa only in 4% yield,
and the recovery of 3a in 75% yield (Table 3, entry 1). However, the thermal decomposition of
4
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1ab with 3a in the presence of 1 equiv of PhCOOH gave 4aa in 55% yield (entry 2). With
reaction time increasing to 10 h, the yield of 4aa increased to 92% (entry 3). To our surprise,
even in the presence of 2 equiv, 3 equiv, and 4 equiv of PhCOOH, 4aa could still obtained in
86%, 78%, and 78% yields, respectively, indicating that this thermal Wittig olefination has a high
tolerance for benzoic acid.
As for the mechanism on this thermal Wittig reaction, we initially thought that Ph4B- might act as
a base to directly abstract a proton (by one phenyl group of Ph4B- to form benzene irreversibly)
from 1 to form ylide 2, which can then react with 3 to give 4. But this possibility was excluded
by the following two control experiments: (1) refluxing a mixture of 1aa and NaBPh4 in CH3CN
at 120 C for 6 h did not produce ylide 2a; instead, 1ab was isolated in 90% yield, and (2)
refluxing 1ab alone in CD3CN at 120 C for 6 h did not produce ylide 2a either, as indicated by
direct NMR analysis of the supernatant after reaction and the recovery of 1ab in 97% yield.
Therefore, we reasoned that the reaction might be catalyzed by a trace of R2COOH, which might
come from oxidation of R2CHO which is hardly to avoid during the process of weighing and
even purifying it. As shown in Scheme 2, R2COOH reacts with Ph4B- to form [R2COOBPh4]-,
which dissociates to BPh3 and R2COO- and the latter acts as a base to abstract an -proton of
phosphonium cation to form ylide 2 and regenerate R2COOH. Obviously, this mechanism could
also explain the high tolerance for benzoic acid for the reaction, considering that Ph4B- has four
phenyl groups to react with stoichiometric or even excess benzoic acid and thus could act like a
5
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
buffering agent.
In summary, we have demonstrated that thermal decomposition of (substituted
methyl)triphenylphosphonium tetraphenylborates with aldehydes directly afforded Wittig
olefination products, without using any additional base. This thermal Wittig olefination could
also be carried out in one-pot by generated in situ the phosphonium tetraphenylborates from the
corresponding phosphonium halides and NaBPh4. Because this reaction is carried out at nearly
neutral conditions and is highly tolerant of benzoic acid, it may find application in the olefination
of some base-sensitive aldehydes or in a one-pot synthesis by combining with some thermal
reactions.
Experimental Section
General. NMR spectra were obtained on a MercuPlus 400 NMR spectrometer (1H NMR at 400
MHz, 13C NMR at 100 MHz, 11B NMR at 128 MHz, and 31P NMR at 162 MHz). IR spectra were
obtained on a Thermo Nicolet Avatar 360 IR spectrometer using KBr disks. Elemental analysis
was performed on a Heraeus Vanio-EL CHN analyzer. All solvents were distilled before use. All
aldehydes were purified by preparative TLC before use. All olefination reactions were performed
under nitrogen by connecting to a nitrogen balloon, and the reaction temperatures were referred
to oil bath temperatures. Phosphonium salts 1aa,[19] 1ba,[20] 1cc,[21] 1da
(benzyltriphenylphosphonium chloride),[22] and 1ed (methyltriphenylphosphonium iodide)[23]
were prepared using the literature methods. Products 4aa-4ad, 4af-4aj, 4al, 4an, 4ca, 4ba, and
6
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
4ap were identified by comparing their NMR spectra with those reported.[24-27] Products 4ae,
4ak, 4am, and 4ao are known[28-30] compounds but no NMR spectrum is available to compare
with, so HRMS were determined for these products. PE = petroleum ether (bp 60-90 C). The
Supplemental Materials contains characterization data for known products.
Synthesis of (cyanomethyl)triphenylphosphonium tetraphenylborate (1ab). A saturated
solution of 1aa (3.38 g, 10 mmol) in water was mixed with a saturated solution of NaBPh4 (3.42
g, 10 mmol) in water under stirring. The resulting white solids was filtered off, washed with
water, and dried in vacuo to afford 1ab (5.7 g) in 92% yield. Further crystallization from CH3CN
afforded pure 1ab (1.9 g) as colorless short needles in 31% yield, mp 221-224 C. IR (cm-1):
1
2258 (CN). H-NMR (DMSO-d6)  5.73 (d, JP-H = 16.0 Hz, 2 H), 6.80-6.85 (m, 4 H), 6.94-6.99
13
(m, 8 H), 7.22-7.28 (m, 8 H), 7.80-7.89 (m, 12 H), 7.95-7.99 (m, 3 H). C-NMR (DMSO-d6) 
14.5 (d, JP-C = 55.7 Hz), 113.3 (d, JP-C = 9.2 Hz), 116.6 (d, JP-C = 88.2 Hz), 122.1, 125.8, 131.1 (d,
JP-C = 13.1 Hz), 134.2 (d, JP-C = 10.8 Hz), 136.1, 136.6 (d, JP-C = 2.8 Hz), 163.9 (q, JB-C = 49.0
11
Hz). B-NMR (DMSO-d6)  -6.6. 31P-NMR (DMSO-d6)  21.2. HRMS-ESI (negative): calcd
for C24H20B- (Ph4B-), 319.1664; found, 319.1662. HRMS-ESI (positive): calcd for C20H17NP+
(Ph3P+CH2CN), 302.1093; found, 302.1096. Elemental analysis: calcd for C44H37BNP: C, 85.02;
H, 6.00; N, 2.25; found: C, 85.32; H, 6.06; N, 2.43. Phosphonium tetraphenylborates 1bb, 1cb,
1db, and 1eb were obtained by the similar procedure from 1ba, 1ca, 1da, and 1ed, respectively.
7
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
(Carbethoxyethyl)triphenylphosphonium tetraphenylborate (1bb). Colorless needles, yield:
55% (after crystallization from EtOAc/CH3CN), mp: 185-187 C. IR (cm-1): 1727 (C=O).
1H-NMR (DMSO-d6)  0.99 (t, J = 7.0 Hz, 3 H), 4.06 (q, J = 7.0 Hz, 2 H), 5.33 (d, JP-H = 14.4
Hz, 2 H), 6.80-6.84 (m, 4 H), 6.93-6.98 (m, 8 H), 7.20-7.30 (m, 8 H), 7.71-7.90 (m, 15 H).
13C-NMR (DMSO-d6)  14.0, 30.0 (d, JP-C = 55.3 Hz), 62.9, 118.6 (d, JP-C = 88.3 Hz), 122.0,
125.8 (q, JBC = 2.5 Hz), 130.6 (d, JP-C = 12.9 Hz), 134.2 (d, JP-C = 10.7 Hz), 135.6 (d, JP-C = 2.7
Hz), 136.1, 163.9 (q, JBC = 49.0 Hz), 165.1 (d, JP-C = 3.6 Hz). 31P-NMR (DMSO-d6)  20.4.
11B-NMR (DMSO-d6)  -6.6. HRMS-ESI (negative): calcd for C24H20B- (Ph4B-), 319.1664;
found, 319.1660. HRMS-ESI (positive): calcd for C22H22O2P+ (Ph3P+CH2COOEt), 349.1352;
found, 349.1354.
(2-Oxo-2-phenylethyl)triphenylphosphonium tetraphenylborate (1cb). A saturated solution
of 1cc in MeOH was used instead, and no solid precipitated until the reaction mixture was stirred
overnight. Short colorless needles, yield: 67% (after crystallization from EtOAc/CH3CN), mp:
1
168-169 C. IR (cm-1): 1675 (C=O). H-NMR (DMSO-d6)  6.23 (d, JP-H = 13.2 Hz, 2 H),
6.79-6.84 (m, 4 H), 6.93-6.98 (m, 8 H), 7.21-7.27 (m, 8 H), 7.59-7.64 (m, 2 H), 7.70-7.78 (m, 7
13
H), 7.83-7.90 (m, 9 H), 8.13 (d, J = 7.6 Hz, 2 H). C-NMR (DMSO-d6)  35.7 (d, JP-C = 61.2
Hz), 119.5 (d, JP-C = 88.5Hz), 122.0, 125.7-125.9 (m), 129.5, 129.6, 130.5 (d, JP-C = 12.9 Hz),
8
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
134.1 (d, JP-C = 10.5 Hz), 135.2 (d, JP-C = 2.6 Hz), 135.5, 135.6 (d, J = 7.4 Hz), 136.1, 163.9 (q,
11
JB-C = 49.0 Hz), 192.9 (d, JP-C = 6.1 Hz). 31P-NMR (DMSO-d6) 21.2. B-NMR (DMSO-d6)
-6.6. HRMS-ESI (negative): calcd for C24H20B- (Ph4B-), 319.1664; found, 319.1665.
HRMS-MALDI (positive): calcd for C26H22OP+ (Ph3P+CH2COPh), 381.1403; found, 381.1406.
Benzyltriphenylphosphonium tetraphenylborate (1db). A white solid, yield: 56%, mp:
237-240 C. 1H-NMR (DMSO-d6)  5.15 (d, JP-H = 15.6 Hz, 2 H), 6.78-6.83 (m, 4 H), 6.92-6.96
(m, 8 H), 6.98-7.01 (m, 2 H), 7.20-7.26 (m, 10 H), 7.29-7.31 (m, 1 H), 7.63-7.72 (m, 12 H),
7.86-7.90 (m, 3 H). 13C- NMR (DMSO-d6)  28.7 (d, JP-C = 46.8 Hz), 118.2 (d, JP-C = 84.9 Hz),
122.0, 125.8 (dd, J1BC = 2.7 Hz, J2BC = 5.2 Hz), 128.3 (d, JP-C = 8.4 Hz), 128.9 (d, JP-C = 3.3 Hz),
129.3 (d, JP-C = 3.1 Hz), 130.6 (d, JP-C = 12.3 Hz), 131.3 (d, JP-C = 5.5 Hz), 134.5 (d, JP-C = 9.8
Hz), 135.6 (d, JP-C = 2.5 Hz), 136.1, 163.9 (q, JBC = 48.9 Hz). 31P-NMR (DMSO-d6)  23.1.
11B-NMR (DMSO-d6)  -6.6. HRMS-ESI (negative): calcd for C24H20B- (Ph4B-), 319.1664;
found, 319.1660. HRMS-ESI (positive): calcd for C25H22P+ (Ph3P+CH2Ph), 353.1454; found,
353.1452.
Methyltriphenylphosphonium tetraphenylborate (1eb). A white solid, yield: 66%, mp:
200-202 C (lit. [31] 197 C). 1H-NMR (DMSO-d6)  3.13 (d, JP-H = 14.4 Hz, 3 H), 6.78-6.83 (m,
4 H), 6.92-6.96 (m, 8 H), 7.20-7.26 (m, 8 H), 7.73-7.79 (m, 12 H), 7.86-7.90 (m, 3 H). 13C-NMR
(DMSO-d6)  7.8 (d, JP-C = 55.8 Hz), 120.3 (d, JP-C = 87.7 Hz), 122.0, 125.8 (dd, J1BC = 2.2 Hz,
9
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
J2BC = 5.0 Hz), 130.6 (d, JP-C = 12.6 Hz), 133.7 (d, JP-C = 10.7 Hz), 135.3 (d, JP-C = 3.0 Hz),
136.1, 163.9 (q, JBC = 49.0 Hz). 31P-NMR (DMSO-d6)  22.6. 11B-NMR (DMSO-d6)  -6.6.
HRMS-ESI (negative): calcd for C24H20B- (Ph4B-), 319.1664; found, 319.1657. HRMS-ESI
(positive): calcd for C19H18P+ (Ph3P+CH3), 277.1141; found, 277.1143.
General procedure for thermal Wittig olefination using phosphonium tetraphenylborate
(1ab-1eb). To a round-bottom flask (50 mL), phosphonium tetraphenylborate (0.4 mmol), 3a
(56.2 mg, 0.4 mmol), and solvent (5 mL) were added. After refluxing at 120 C for 6 h under
stirring, the reaction mixture was passed through a short silica-gel column and eluted with
EtOAc. The eluate was evaporated and the olefination product was isolated from the residue by
preparative TLC (silica-gel).
Typical procedure for thermal Wittig olefination using phosphonium halide. To a
round-bottom flask (50 mL), 1aa (168.9 mg, 0.5 mmol), NaBPh4 (171.1 mg, 0.5 mmol), 3a (56.2
mg, 0.4 mmol), and CH3CN (5 mL) were added. After refluxing at 120 C for 6 h under stirring,
the reaction mixture was passed through a short silica-gel column and eluted with EtOAc. The
eluate was evaporated and 4aa (58.0 mg, 89%, trans: cis = 69:31) was isolated as a mixture of
trans and cis isomers from the residue by preparative TLC (silica-gel, PE: EtOAc 10:1). By
carefully choosing the eluants (PE: EtOAc 50:1, v/v, once; then CCl4, twice), the trans isomer
can be separated from the cis isomer in this mixture. The trans and cis isomers were identified by
comparing their 1H NMR spectra with those reported.[6] trans-4aa: a yellow solid, isolated yield:
10
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
54%. IR (cm-1): 2215 (CN). 1H-NMR (CDCl3)  5.88 (d, J = 16.8 Hz, 1 H), 7.37 (d, J = 16.8 Hz,
13
1 H), 7.39-7.41 (m, 4 H). C-NMR (CDCl3)  97.0, 117.8, 128.6, 129.4, 132.0, 137.3, 149.1.
cis-4aa: a white solid, isolated yield: 27%. IR (cm-1): 2211 (CN). 1H-NMR (CDCl3)  5.50 (d, J
= 12.0 Hz, 1 H), 7.11 (d, J = 12.0 Hz, 1 H), 7.44 (d, J = 8.6 Hz, 2 H), 7.77 (d, J = 8.6 Hz, 2 H).
13C-NMR (CDCl3)  95.7, 117.1, 129.3, 130.3, 132.0, 137.0, 147.3.
Control experiment A—thermolysis of 1aa with 3a in the absence of NaBPh4. To a
round-bottom flask (50 mL), 1aa (135.1 mg, 0.4 mmol), 3a (56.2 mg, 0.4 mmol), and CH3CN (5
mL) were added. After refluxing at 120 C for 6 h under stirring, the reaction mixture was
worked up as the general procedure A to afford 4aa (29.5 mg) in 35% yield as a mixture of trans
and cis isomers (trans:cis = 65:35, determined by 1H-NMR).
Control experiment B—thermolysis of 1ab in the absence of aldehyde. To a round-bottom
flask (50 mL), 1ab (186.5 mg, 0.3 mmol) and CD3CN (3 mL) were added. After refluxing at 120
C for 6 h under stirring, the supernatant was directly analyzed by 1H-NMR, which showed there
was only phosphonium salt 1ab in the supernatant. Then the reaction mixture was evaporated to
remove CD3CN, and the residue was washed with ether and dried in vacuo to give a white solid
1
13
11
31
(180.9 mg), which was identified by H-, C-, B-, and P-NMR as phosphonium salt 1ab in
97% yield.
11
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Control experiment C—thermolysis of 1aa and NaBPh4 in the absence of aldehyde. To a
round-bottom flask (50 mL), 1aa (168.9 mg, 0.5 mmol), NaBPh4 (171.1 mg, 0.5 mmol), and
CH3CN (5 mL) were added. After refluxing at 120 C for 6 h under stirring, the reaction mixture
was filtered. The filtercake was washed with water (50 mL) and dried in vacuo to give a white
11
31
solid (279.2 mg), which was identified by 1H-, 13C-, B-, and P-NMR to be phosphonium salt
1ab in 90% yield.
Thermolysis of phosphonium tetraphenylborate 1ab with aldehyde 3a in the presence of
benzoic acid. To a three-neck flask (50 mL), 1ab (248.6 mg, 0.4 mmol), benzoic acid, and
acetonitrile (3 mL) were added. After refluxing at 120 C for 1 h, 3a (56.2 mg, 0.4 mmol) in
acetonitrile (2 mL) was added to the reaction mixture by a syringe. The reaction mixture was
allowed to reflux for a certain time, and then worked up as the general procedure A to give 4aa.
The results were summarized in Table 3.
Acknowledgment. We thank the National Natural Science Foundation of China (No. 21272170)
for their financial support of our program.
12
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
References
[1] Maercker, A. Org. React. 1965, 14, 270-490.
[2] Miller, N. E. J. Am. Chem. Soc. 1965, 87, 390-391.
[3] Castaneda, F.; Aliaga, C.; Acuna, C.; Silva, P.; Bunton, C. A. Phosphorus, Sulfur Silicon
Relat. Elem., 2008, 183, 1188-1208.
[4] Bissing, D. E. J. Org. Chem. 1965, 30, 1296-1298.
[5] Poleschner, H.; Seppelt, K. J. Fluorine Chem. 2003, 120, 49-58.
[6] Asay, M.; Donnadieu, B.; Baceiredo, A.; Soleihavoup, M.; Bertrand, G. Inorg. Chem. 2008,
47, 3949-3951.
[7] Nakafuji, S.; Kobayashi, J.; Kawashima, T. Angew. Chem. Int. Ed. 2008, 47, 1141-1144.
[8] Schiemenz, G. P.; Nathe, C.; Porksen, S. Z. Naturforsch. 2003, 58b, 663-671.
[9] Zhao, Q.; Cao, X.-Y.; Wen, T. B.; Xia, H. Chem. Asian J. 2013, 8, 269-275.
[10]Okuma, K.; Yoshitake, K.; Izaki, T.; Yoshida, K.; Shioji, K. Bull. Chem. Soc. Jpn. 2007, 80,
1785-1790.
[11]Yamamoto, S.; Okuma, K.; Ohta, H. Bull. Chem. Soc. Jpn. 1988, 61, 4476-4478.
[12]Andrews, D. R.; Barton, D. H. R.; Hesse, R. H.; Pechet, M. M. J. Org. Chem. 1986, 51,
4819-4828.
[13]Liu, S. H.; Xia, H.; Wan, K. L.; Yeung, R. C. Y.; Hu, Q. Y.; Jia, G. J. Organomet. Chem.
2003, 683, 331-336.
[14]Bollans, L.; Bacsa, J.; O'Farrell, D. J.; Waterson, S.; Stachulski, A. V. Tetrahedron Lett. 2010,
51, 2160-2163.
13
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
[15]Patil, V. J.; Mavers, U. Tetrahedron Lett. 1996, 37, 1281-1284, and references cited therein.
[16]Thiemann, T.; Thiemann, C.; Sasaki, S.; Vill, V.; Mataka, S.; Tashiro, M. J. Chem. Res. 1997,
248-249.
[17]Corey, E. J.; Clark, D. A.; Goto, G.; Marfat, A.; Mioskowski, C.; Samuelsson, B.;
Hammarstrom, S. J. Am. Chem. Soc. 1980, 102, 1436-1439.
[18]Wu, J.; Yue, C. Synth. Commun. 2006, 36, 2939-2947.
[19]Aitken, R. A.; Al-Awadi, N. A.; El-Dusouqui, O. M. E.; Farrell, D. M. M.; Kumar, A. Int. J.
Chem. Kinet. 2006, 38, 496-502.
[20]Castaneda, F.; Aliaga, C.; Acuna, C.; Silva, P.; Bunton, C. A. Phosphorus, Sulfur Silicon
Relat. Elem. 2008, 183, 1188.
[21]Ramirez, F.; Dershowitz, S. J. Org. Chem. 1957, 22, 41-45.
[22]Sun, W.-T.; Huang, Y.-T.; Huang, G.-J.; Lu, H.-F.; Chao, I.; Huang, S.-L.; Huang, S.-J.; Lin,
Y.-C.; Ho, J.-H.; Yang, J.-H. Chem. Eur. J. 2010, 16, 11594-11604.
[23]Vikse, K. L.; Ahmadi, Z.; Manning, C. C.; Harrington, D. A.; McIndoe, J. S. Angew. Chem.
Int. Ed. 2011, 50, 8304-8306.
[24]Wu, J.; Yue, C. Synth. Commun. 2006, 36, 2939-2947.
[25]Huang, X.; Xie, L.; Wu, H. J. Org. Chem. 1988, 53, 4862-4864.
[26]Fang, F.; Li, Y.; Tian, S.-K. Eur. J. Org. Chem. 2011, 1084-1091.
[27]Kojima, S.; Fukuzaki, T.; Yamakawa, A.; Murai, Y. Org. Lett. 2004, 6, 3917-3920.
[28]Kobuke, Y.; Fukui, Y.; Furukawa, J.; Fueno, T. J. Polym. Sci. Part A-1 1970, 8, 3155-3162.
[29]Cowles, R. S.; Miller, J. R.; Hollingworth, R. M.; Abdel-Aal, M. T.; Szurdoki, F.; Bauer, K.;
Matolcsy, G. J. Chem. Ecol.1990, 16, 2401-2428.
14
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
[30]Tanaka, D.; Romeril, S. P.; Myers, A. G. J. Am. Chem. Soc. 2005, 127, 10323-10333.
[31]Shestakova, E. P.; Varshavsky, Y. S.; Lyssenko, K. A.; Korlyukov, A. A.; Khrustalev, V. N.;
Andreeva, M. V. J. Organomet. Chem. 2004, 689, 1930-1943.
Scheme 1
Scheme 2 Proposed reaction mechanism on the
formation of ylide 2
15
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Table 1. Initial observations on thermal decomposition of 1 with 3aa
Entr R1
y
X
Solvent
Yield(%)b of
4a
1
4a
1
CN
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
Ph4B
toluene
CH3CN
THF
64c (68:32)
92 (71:29)
74 (74:26)
59 (53:47)
61 (77:23)
45 (89:11)
39 (81:19)
54 (81:19)
68 (66:34)
54 (60:40)
69 (72:28)d
61c (97:3)
1ab
1ab
1ab
1ab
1ab
1ab
1ab
1ab
1ab
1ab
1bb
1cb
4aa
4aa
4aa
4aa
4aa
4aa
4aa
4aa
4aa
4aa
4ba
4ca
2
CN
CN
CN
CN
CN
CN
CN
CN
CN
3
4
EtOH
5
EtOAc
Acetone
DCE
6
7
8
1,4-Dioxane
DMSO
DMF
9
10
11
12
COOEt Ph4B
COPh Ph4B
CH3CN
CH3CN
16
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
13
14
15
Ph
Ph4B
Ph4B
Cl
CH3CN
CH3CN
CH3CN
Not detected
Not detected
35 (65:35)
1db
1eb
1aa
4da
4ea
4aa
Me
CN
aReaction conditions: 1 (0.4 mmol), 3a (0.4 mmol), solvent (5 mL), refluxed at
b
120 C (bath temperature) for 6 h. Isolated yield of 4a. The numbers in
1
parentheses are the ratios of trans to cis isomers determined by H-NMR.
cReaction time: 12 h. dThe isolated ratio of trans to cis isomers.
17
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Table 2. Thermal decomposition of phosphonium chloride 1aa and NaBPh4
with aldehyde 3a
Entry
1
R1
X
R2
Yield (%) of 4
89 (69:31)b
92 (58:42)c
82 (69:31)b
92 (45:55)c
94 (59:41)c
93 (72:28)b
63 (78:22)b
75 (79:21)b
80 (65:35)b
57 (72:28)c
60 (65:35)c
49d (71:29)c
44 (57:43)b
1
3
3a
3b
3c
3d
3e
3f
4
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
4-ClC6H4
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
1aa
4aa
4ab
4ac
4ad
4ae
4af
4ag
4ah
4ai
2
2-ClC6H4
3
4-O2NC6H4
2-O2NC6H4
3-O2NC6H4
4-BrC6H4
4
5
6
7
4-FC6H4
3g
3h
3i
8
Ph
9
1-naphthyl
4-MeC6H4
3,4-(MeO)2C6H3
4-MeOC6H4
2,4-(MeO)2C6H3
10
11
12
13
3j
4aj
4ak
4al
3k
3l
3m
4am
18
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
14
15
CN
CN
Cl
Cl
2-HOC6H4
4-HO-3-MeOC6
H3
40 (100:0)b
1aa
1aa
3n
3o
4an
4ao
100 (74:26)b
16
17
CN
Cl
PhCH2CH2
4-ClC6H4
22 (63:37)b
69e (86:14)c
1aa
1ba
3p
3a
4ap
4ba
COO Cl
Et
18
COPh Br
4-ClC6H4
80e (100:0)b
1cc
3a
4ca
aReaction conditions: 1 (0.5 mmol), NaBPh4 (0.5 mmol), 3 (0.4 mmol), and
b
CH3CN (5 mL), refluxed at 120 C (bath temperature) for 6 h. The trans: cis
1
c
d
ratios determined by H-NMR. The isolated ratios of trans to cis isomers. For
e
reaction time of 12 h, the yield increased to 72% (trans: cis = 75:25). Refluxed
for 12 h.
19
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Table 3. Thermal decomposition of 1ab and 3a in the
presence of PhCOOHa
Entr PhCOO
Timeb
Yield(%) of
trans:cis of
4aa
y
1
2
3
4
5
6
H
4aa
4c (75)d
55
1 equiv
1 equiv
1 equiv
2 equiv
3 equiv
4 equiv
5 h
5 h
83:17
79:21
77:23
80:20
76:24
83:17
10 h
10 h
10 h
10 h
92
86
78
78
aReaction conditions: 1ab (0.4 mmol), PhCOOH,
acetonitrile (3 mL), 120 C (oil bath), 1 h, then 3a (0.4
b
c
mmol). Reaction time after adding 3a. Use 2a instead of
1ab. dThe recovered yield of 3a.
20
ACCEPTED MANUSCRIPT