A new method to prepare functional phosphines through steady-state photolysis of triarylphosphines

Article abstract of DOI:10.1002/hc.21468

The steady-state photolysis of triarylphosphine, Ar₃P, was carried out using a xenon lamp or a high-pressure mercury lamp under an argon atmosphere in a solvent containing a functional group, CH₃X. Gas chromatograph-mass spectroscopic analysis on the photolysis showed that a phosphine to which the functional group from the solvent is incorporated, Ar₂PCH₂X, was formed in a moderate yield, along with tetraaryldiphosphine, Ar₂PPAr₂. The product, Ar₂PCH₂CN, from the photolysis in acetonitrile (X=CN) was isolated by column chromatography. In the photolysis in other solvents tried here (ethyl acetate, acetone, 2-butanone, and 3,3-dimethyl-2-butanone), Ar₂PCH₂X formed in the reaction mixture was so labile on a silica-gel column that it was treated with S₈ powder to convert to the corresponding phosphine sulfide, Ar₂P(=S)CH₂X. The resulting phosphine sulfide was isolated by column chromatography. The isolated products in these reactions, Ar₂PCH₂CN and Ar₂P(=S)CH₂X, were characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, IR spectroscopy, and elemental analysis or high-resolution mass spectroscopy. The formation of Ar₂PCH₂X as well as Ar₂PPAr₂ is explained by homolytic cleavage of a P-C bond of Ar₃P in the photoexcited state. This reactivity of Ar₃P in the photoexcited state is in sharp contrast to that exerted under aerobic conditions, where Ar₃P in the photoexcited state donates readily an electron to oxygen producing the radical cation, Ar₃P^·+. This photoreaction, which affords a functional phosphine, Ar₂PCH₂X, in one-pot with generating very small amounts of unidentified side products, has potential for use in preparing functional phosphines.

Full text of DOI:10.1002/hc.21468

Received: 26 September 2018
DOI: 10.1002/hc.21468
Revised: 16 November 2018
Accepted: 16 November 2018
|
|
S P E C I A L I S S U E : A T R I B U T E T O P R O F E S S O R
N A O M I C H I F U R U K AWA O N T H E O C C A S I O N O F
H I S 8 2 N D B I R T H D AY - B Y I N V I T AT I O N O N LY
A new method to prepare functional phosphines through steady-
state photolysis of triarylphosphines*
Shinro Yasui1
Taro Ando2
Masashi Ozaki2
Yuya Ogawa2
Kosei Shioji2
|
|
|
|
1Institute of Human and Environmental
Sciences, Tezukayama University, Nara,
Japan
2Department of Chemistry, Faculty of
Science, Fukuoka University, Fukuoka,
Japan
Abstract
The steady-state photolysis of triarylphosphine, Ar3P, was carried out using a xenon
lamp or a high-pressure mercury lamp under an argon atmosphere in a solvent con-
taining a functional group, CH3X. Gas chromatograph-mass spectroscopic analysis
on the photolysis showed that a phosphine to which the functional group from the
solvent is incorporated, Ar2PCH2X, was formed in a moderate yield, along with
tetraaryldiphosphine, Ar2PPAr2. The product, Ar2PCH2CN, from the photolysis in
acetonitrile (X=CN) was isolated by column chromatography. In the photolysis in
other solvents tried here (ethyl acetate, acetone, 2-butanone, and
3,3-dimethyl-2-butanone), Ar2PCH2X formed in the reaction mixture was so labile
on a silica-gel column that it was treated with S8 powder to convert to the corre-
sponding phosphine sulfide, Ar2P(=S)CH2X. The resulting phosphine sulfide was
isolated by column chromatography. The isolated products in these reactions,
Ar2PCH2CN and Ar2P(=S)CH2X, were characterized by 1H, 13C, and 31P NMR spec-
troscopy, IR spectroscopy, and elemental analysis or high-resolution mass spectros-
copy. The formation of Ar2PCH2X as well as Ar2PPAr2 is explained by homolytic
cleavage of a P-C bond of Ar3P in the photoexcited state. This reactivity of Ar3P in
the photoexcited state is in sharp contrast to that exerted under aerobic conditions,
where Ar3P in the photoexcited state donates readily an electron to oxygen producing
the radical cation, Ar3P·+. This photoreaction, which affords a functional phosphine,
Ar2PCH2X, in one-pot with generating very small amounts of unidentified side prod-
ucts, has potential for use in preparing functional phosphines.
Correspondence
Shinro Yasui, Institute of Human and
Environmental Sciences, Tezukayama
University, Nara, Japan.
Email: yasui@tezukayama-u.ac.jp
photoexcited, may exert novel reactivity.[1–2] Through
steady-state photolysis and laser flash photolysis, we found
1
INTRODUCTION
|
In the chemistry of organic synthesis, photolysis is a pow-
erful option, which could bring about reactions that cannot
occur in the dark. We have been studying nonsensitized
photolysis of phosphines expecting that phosphines, when
that phosphine-bearing chromophores, such as triarylphos-
phine, Ar3P, are directly photoexcited to its singlet excited
1
state, Ar3P*, which undergoes various reactions depend-
1
ing on the conditions. Under aerobic conditions, Ar3P*
undergoes electron transfer to oxygen in the ground state,
generating the phosphine radical cation, Ar3P·+. The re-
sulting radical cation, Ar3P·+, undergoes an ionic reaction
and a radical reaction competitively.[1c] Another interesting
Dedicated to 82nd birthday of Professor Naomichi Furukawa.
*Steady-state photolysis of triarylphosphine under anaerobic conditions re-
sults in homolytic cleavage of a P-C bond, the resulting radicals affording a
phosphine to which a functional group from a solvent is incorporated.
1
finding is that homolytic cleavage of a P-C bond in Ar3P*
|
Heteroatom Chemistry. 2018;e21468.
https://doi.org/10.1002/hc.21468
wileyonlinelibrary.com/journal/hc
© 2018 Wiley Periodicals, Inc.
1 of 8

2 of 8
YASUI et Al.
|
Ar2PCH2CN (2)
ArH (3)
2
RESULTS AND DISCUSSION
|
Xenon lamp (> 310 nm)
Ar3P
in MeCN under an argon atm.
2.1
Steady-state photolysis of
|
Ar2P-PAr2 (4)
Ar
triarylphosphine (1) in acetonitrile
1a; 2-Tolyl
1b; 4-Tolyl
1c; Mesityl
Westudiedpreviouslythephotolysisoftriarylphosphine, Ar3P
(1a; Ar = 2-tolyl, 1b; Ar = 4-tolyl, 1c; Ar = mesityl), using a
xenon lamp under an argon atmosphere at room temperature
in acetonitrile (MeCN) (Scheme 1).[2] Analysis by gas chro-
matography (GC) and gas chromatograph-mass spectroscopy
(GCMS) showed the formation of diaryl(cyanomethyl)phos-
phine (2a-c). The formation of mesitylene (MesH; 3c; 92%)
was also shown by GCMS in the photolysis of 1c. An invola-
tile product, tetraaryldiphosphine, Ar2PPAr2 (4a (−37.7 ppm)
or 4c (−29.4 ppm)),[5,6] was detected by 31P NMR spectros-
copy in the photolysis of 1a or 1c in MeCN-d3, along with
2a-d2 (−35.1 ppm) or 2c-d2 (−24.7 ppm). The products 2 and
SCHEME 1 Steady-state photolysis of 1 in MeCN under an
argon atmosphere
takes place under anaerobic conditions to afford diaryl-
phosphanyl radical, Ar2P·, and aryl radical, Ar·.[2] In fact,
when we carried out the steady-photolysis of Ar3P in ace-
tonitrile (MeCN) under an argon atmosphere, we found the
formation of the products resulting from Ar2P·, namely, di-
aryl(cyanomethyl)phosphine, Ar2PCH2CN, and tetraaryldi-
phosphine, Ar2PPAr2. In this reaction, Ar· picks up an
α-hydrogen in the MeCN molecule to give cyanomethyl rad-
ical, ·CH2CN, and arene, ArH. The former radical couples
with Ar2P· to afford Ar2PCH2CN. Anticipating that a similar
photoreaction would take place in other solvents as well, we
photolyzed Ar3P in a solvent containing a functional group,
CH3X, namely, ethyl acetate, acetone, 2-butanone, and
3,3-dimethyl-2-butanone. As expected, we found the forma-
tion of Ar2PCH2X in the photolysis of Ar3P under an argon
atmosphere in these solvents.[3]
Phosphines we obtained here, Ar2PCH2X (X=CN, (C=O)
R, (C=O)OR), belong to a family of functional phosphines.
These phosphines are important in coordination chemistry
because they can tune reactivity of a transition metal com-
plex by coordinating to a transition metal in several ways.[4]
In this paper, we present the results from the photolysis of
Ar3P under an argon atmosphere in several solvents. We dis-
cuss possibility in using this photoreaction for preparation of
functional phosphines.
4 were isolated and characterized by H, 13C, and 31P NMR
1
spectroscopy as well as IR spectroscopy. Table 1 summarizes
the yields of 2 determined by GC in the photolysis under vari-
ous reaction conditions. The yield of 2 depends on the wave-
lengths of the irradiating light. The more the light absorbed by
1, the higher the yield of 2.
The photolysis of 1c was also performed using a xenon
lamp under an argon atmosphere in ethyl acetate (AcOEt)
and acetone (MeCOMe). The GCMS analysis of the reac-
tion mixture strongly suggested the formation of dimesityl(-
carboethoxymethyl)phosphine, Mes2PCH2C(=O)OEt (5c),
and dimesityl(acetylmethyl)phosphine, Mes2PCH2C(=O)
Me (6c), respectively. However, an attempt to isolate these
products by column chromatography failed. Probably, 5c
and 6c were too sensitive to oxidation to remain intact on
the silica-gel column. We then converted the product to the
stable phosphine sulfide before isolation by treating with
S8 powder (see Section 4). The resulting phosphine sulfide,
Mes2P(=S)CH2C(=O)OEt (5cS) or Mes2P(=S)CH2C(=O)
TABLE 1 GC analysis of photolysis of Ar3P (1) by a xenon lampa
Yield (%)b
Entry
Ar3P (1)
Ar
Irradiated at (nm)
Time (min)
1c
2
Ar3P=Od
1
2
3
4
5
1a
1b
2-Tolyl
4-Tolyl
>310 (3.20)e
>310 (2.80)e
>350 (1.69)e
>310 (4.16)e
>420 (—)h
45
180
60
7
0
>29 [6]f
7
16
5
5
5
10
77
0
>26
0
53 [46]g
0
1c
Mesityl
60
88
aAt room temperature. [1] = 1.0 × 10−3 mol/L. Data from Ref.[2b]
bDetermined by GC based on the initial amount of 1 unless otherwise indicated.
cRecovered.
dThe system may be contaminated by a trace amount of O2.
eThe values in parentheses denote logε, where ε is the extinction coefficient (mol L−1 cm−1) of the shortest wavelength of the irradiating light.
fThe values in brackets denote isolated yield after 180 min irradiation.
gThe values in brackets denote isolated yield after 20 min irradiation.
hNo absorption observed.

YASUI et Al.
3 of 8
|
FIGURE 1 IR spectra of
Mes2P(=S)CH2C(=O)OEt (5cS). Lower (in
black); Observed by FT-IR spectrometer
in carbon tetrachloride (0.04 mmol/L).
Upper (in gray); Simulated based on DFT
B3LYP/6-31G(d) with the scaling factor of
0.9613. Ref.[7]
500
1000
1500
2000
2500
3000
3500
wavenumber / cm-1
FIGURE 2 IR spectra of
Mes2P(=S)CH2C(=O)Me (6cS). Lower (in
black); Observed by FT-IR spectrometer
in carbon tetrachloride (0.04 mmol/L).
Upper (in gray); Simulated based on DFT
B3LYP/6-31G(d) with the scaling factor of
0.9613. Ref.[7]
500
1000
1500
2000
2500
3000
3500
wavenumber / cm-1
Me (6cS), from the photolysis in AcOEt or in MeCOMe, re-
spectively, was isolated by column chromatography. A small
amount of 4c was also isolated from each reaction mixture.
The products 5cS and 6cS as well as 4c were characterized
2.2
Photolysis by a high-pressure
|
mercury lamp
The steady-state photolysis of 1c under an argon atmosphere
was carried out using a high-pressure mercury lamp (Hg
lamp). The photolysis with an Hg lamp in MeCN, AcOEt, and
Me(C=O)Me gave the same products as the photolysis with a
xenon lamp. There were no big differences in their yields.
The photolysis under an argon atmosphere was per-
formed in 2-butanone (methyl ethyl ketone; MEK), or
3,3-dimethyl-2-butanone (tert-butyl methyl ketone (pina-
colone); BMK) by an Hg lamp (Entries 4 and 5 in Table 3,
respectively). The products, dimesityl(but-2-one-3-yl)phos-
phine, Mes2PCH(CH3)C(=O)CH3 (7c), and dimesityl(2,2-
1
by H, 13C, and 31P NMR spectroscopy and high-resolution
mass spectrometry. IR spectroscopy on 5cS and 6cS gave the
spectra consistent with the spectra simulated based on DFT
B3LYP/6-31G(d), as shown in Figures 1 and 2, respectively.
Clearly, 5c and 6c are the precursors of 5cS and 6cS formed
during the photolysis in AcOEt and in MeCOMe, respec-
tively (Scheme 2).
The isolated yields of 5cS and 6cS are given in Table 2,
which also reports the yield of 2c from the photolysis in MeCN
for the sake of comparison. During the photolysis, a small
amount of 4c precipitated due to its poor solubility into these
solvents. The precipitates were mixed with S8 powder during
the work-up and were removed through the filtration with S8
powder. Therefore, the isolated yield reported in the last col-
umn of Table 2 is lower than the yield of 4c formed in situ.
dimethylbut-3-one-4-yl)phosphine,
Mes2PCH2C(=O)But
(8c), respectively, were labile on the silica-gel column.
Therefore, the corresponding phosphine sulfides, 7cS and
8cS, obtained by treatment with S8, were isolated, along
with 4c, from the reactions in MEK and BMK, respectively

4 of 8
YASUI et Al.
|
Xenon lamp (> 310 nm)
or Hg lamp
+ S8
Mes3P
Mes2PCH2X
CH2X
Mes2PCH2X
S
in CH3X under an argon atm.
1c
5cS ~ 9cS
5c; CH2C(=O)OEt
6c; CH2C(=O)Me
7c; CH(Me)C(=O)Me
8c; CH2C(=O)But
9c; CH2OH
SCHEME 2 Steady-state photolysis
of 1c in various solvents
TABLE 2 Photolysis of Mes3P (1c) by a xenon lampa
Solvent; CH3X
Isolated
Entry
(mL)b
CH2X
1c (mg)c
Y
Mes2P(=Y)CH2X
yield (%)
1d
2e
3e
MeCN [60]b
AcOEt [50]b
MeCOMe [52]b
CH2CN
CH2C(=O)OEt
CH2C(=O)Me
53.51
52.86
54.40
Lone pair
S
S
2c
5cS
6cS
46
17
46
aAt room temperature under an argon atmosphere for 60 min. [1c] = (2.3~2.8) × 10−3 mol/L.
bNumbers in brackets denote sum of the solvent in five experiments in mL.
cSum of 1c in five experiments in mg.
dData from Entry 4 in Table 1.
eS8 powder was added immediately after the photolysis.
(Scheme 2). Due to the precipitation of 4c during the reac-
tion, Table 3 reports a lower yield of 4c than that in situ.
reaction, which supports the radical mechanism for the pres-
ent photoreaction.
2.3
Regioselectivity of the photoreaction
2.4
Mechanistic aspects
|
|
In the photolysis in MEK, 7cS was obtained exclusively
(Table 3; Scheme 3), strongly suggesting that 7c is an exclu-
sive product during the photolysis in MEK. DFT calculations
were done on energy of carbon-centered radicals resulting
from hydrogen abstraction from MEK. As shown in Table 4,
2-butanon-3-yl radical (13) is the most stable among the pos-
sible radicals (12~14). The radical 13 is the most likely can-
didate to produce 7c, where the 3-position carbon in MEK is
attached to the phosphorus atom.
As shown in Table 1, the larger the light absorbed by 1, the
higher the yield. Therefore, there is no doubt that the initial
step of the present photoreaction is the photoexcitation of 1 to
its singlet state, 11*. This, directly or after intersystem crossing
3
to its triplet state, 1*, undergoes homolytic cleavage to pro-
duce diarylphosphanyl radical, Ar2P·, and aryl radical, Ar·
(Equation 1).[2b] Homolytic cleavage of a P-C bond in a triar-
ylphosphine has been reported to occur either from the singlet
or the triplet state of the phosphine.[8] The aryl radical, Ar·,
thus generated abstracts a hydrogen from the solvent CH3X to
produce a radical ·CH2X as well as arene, ArH (3) (Equation 2).
The radical ·CH2X would couple with Ar2P· to give Ar2PCH2X
(Equation 3). Summarizing Equations 1-3, the mechanism is
depicted as in Scheme 4.* In support of this mechanism, the
photolysis of trimesitylphosphine, 1c, in MeCN-d3 gave mesi-
tylene-d1, MesD, in a considerable amount, as revealed by
GCMS analysis. In addition, this mechanism well explains the
formation of 4 and diarylphosphine (Ar2PH, 15).
From the photolysis in BMK, 8cS was isolated exclu-
sively (Table 3; Scheme 3). The precursor, 8c, is the product
that would result from more stable radical ·CH2COC(CH3)3
(Table 5). Interestingly, preference based on stability of the
radical overcomes statistical factor in this case. The photolysis
was carried out also in MeOH, where 9cS was isolated upon
the treatment with S8 powder even though its yield is quite low
(Entry 6 in Table 3; Scheme 3). Interestingly, the precursor 9c
is the product expected from the reaction with more stable hy-
droxymethyl radical ·CH2OH (Table 6). Mes2PH (15c) was a
major product in the photolysis in MeOH. Ar2P· would pick up
the hydrogen atom in the hydroxy group much more facilely
than an α-hydrogen, making only a small amount of ·CH2OH
available for the radical coupling with Ar2P·.
1Ar3P∗ ⟶Ar2P⋅+Ar⋅
(1)
*We have determined the intensity of the incident light from our xenon lamp
apparatus based on chemical actinometry. Taking into account this value, the
quantum yield for production of 2c from 1c is roughly estimated to be
10−3~10−2. For details, see Ref.[2b]
In conclusion, the stability of the radicals resulting
from a solvent molecule explains regioselectivity of the

YASUI et Al.
5 of 8
|
TABLE 3 Steady-state photolysis of 1c using a high-pressure Hg lampa
Yield (%)b
Entry
Solvent
CH2X
Y
Mes2P(=Y)CH2X
Mes2PPMes2 (4c)c
1
MeCN
AcOEt
MeCOMe
MeCOEt (MEK)
MeCOBut (BMK)
MeOH
CH2CN
Lone pair
27 (2c)
20
31
16
20
8
2d
3d
4d
5d
6d
CH2C(=O)OEt
CH2C(=O)Me
MeCHC(=O)Me
CH2C(=O)But
CH2OH
S
S
S
S
S
28 (5cS)
47 (6cS)
22 (7cS)
15 (8cS)
5e (9cS)
13
aAt room temperature. Irradiated by light from a high-pressure mercury lamp under an argon atmosphere for 120 min. [1c] = 6.0 × 10−3 mol/L.
bIsolated yield.
cSome part of this material was lost with S8 powder before the column chromatography. See the text.
dS8 powder was added immediately after the photolysis.
eMes2PH (15c) is obtained as a major product.
S
S
S
P
O
P
P
OH
O
Mes
Mes
Mes
Mes
Mes
Mes
SCHEME 3 Isolated products from
7cS
8cS
9cS
the photolysis in MEK, BMK, and MeOH
is not the case. The reaction ceased upon the shutdown of the
irradiation. Therefore, this mechanism is less likely.
Ar⋅+CH3X⟶ArH(3)+⋅CH2X
⋅CH2X+Ar2P⋅⟶Ar2PCH2X
(2)
(3)
⋅
⋅CH2X+Ar3P⟶Ar3 P CH2X⟶Ar2PCH2X+Ar⋅
(4)
Concentrations of Ar2P· and ·CH2X may be too low for
these radicals to encounter each other to combine efficiently.
It seems more plausible that ·CH2X attacks predominantly
upon the parent phosphine Ar3P (Equation 4). According to
this mechanism, phosphoranyl radical, Ar3P·CH2X, is gener-
ated, which collapses to Ar2PCH2X, regenerating aryl radical
Ar· (Equation 4). The radical Ar· acts to regenerate ·CH2X
according to Equation 2. In other words, this mechanism pre-
dicts a catalytic feature taking place in the dark, as depicted
in Scheme 5. However, a control experiment showed that this
2.5
The previously reported methods
|
(Cyanomethyl)phosphines, R2CH2CN (R = alkyl, aryl), have
been prepared by several methods. One method uses the re-
action of chlorophosphines with LiCH2CN.[9] This method is
not applicable to preparation of a functional phosphine hav-
ing an ester or a carbonyl group by using an ester or a ketone
as a solvent, because butyl lithium, which is necessary for
TABLE 4 Energy of radicals
·CH2X
ΔG (kJ mol−1
)
generated from MEK calculated based on
0
DFT B3LYP/6-31+G(d,p)
•
(12)
O
−53.38693947
−27.18942045
•
(13)
(14)
O
•
O

6 of 8
YASUI et Al.
|
TABLE 5 Energy of radicals generated from CH3COC(CH3)3
Ar2PH
15
(BMK) calculated based on DFT B3LYP/6-31+G(d,p)
1Ar3P*
Ar2P•
·CH2X
ΔG (kJ mol−1
)
Ar2P-PAr2
hν
CH3(C=O)C(CH3)2CH2·
·CH2(C=O)C(CH3)3
0
4
Ar2PCH2X
CH3X
−26.19543371
Ar3P
1
2, 5-9
Ar•
TABLE 6 Energy of radicals generated from MeOH calculated
ArH
3
based on DFT B3LYP/6-31+G(d,p)
•
•CH2X
Ar3PCH2X
·CH2X
ΔG (kJ mol−1
)
CH3O·
·CH2OH
0
Ar3P
1
−23.48137766
SCHEME 5 Alternative mechanism of the photoreaction of 1
this method, promotes Claisen condensation of the former or
Aldol reaction of the latter. The other papers have reported
that R2CH2CN is prepared through reduction of (cyanome-
thyl)phosphine oxides obtained by the Arbuzov attack of
phosphinites upon ClCH2CN.[10] For this method, use of an
irritant reductant, diphenylsilane, may be disadvantageous.
under anaerobic conditions
a high-pressure mercury lamp readily gives rise to homolytic
cleavage of a P-C bond may provide a new protocol to obtain
functional phosphines.
4
EXPERIMENTAL
General
|
3
CONCLUSION
|
4.1
|
We have shown that the steady-state photolysis of triaryphos-
phines in a proper solvent under an argon atmosphere affords
functional phosphines. This is a one-pot reaction with giv-
ing very small amounts of unidentified side products. At this
stage of the study, we are not in success in using this method
for synthetic purpose mainly because the conditions have
not been optimized to maximize the yields of the products.
Deprotect of the sulfur atom in the phosphine sulfide is an-
other problem to be overcome. Nevertheless, the finding that
a conventional irradiation apparatus such as a xenon lamp or
Photolysis was performed by an Ushio xenon short arc UXL-
500D-0 lamp and a 100 W high-pressure mercury lamp with
a RIKO UVL-100P photochemical reactor.
Analysis by a GCMS was performed using a JEOL
JMS-GC mate II spectrometer. H, 13C, and 31P NMR
1
spectra were recorded by a Bruker BioSpin AVANCE-III
against TMS (1H and 13C) and 85% H3PO4 (31P). IR spectra
were recorded on a JASCO FT/IR-4200 with a KRS-5 cell
(0.01 cm).
NMR spectroscopy was performed on the acetonitrile-d3
solution of 1a or 1c (2.0 × 10−3 mol/L) prepared in a quartz
NMR tube under an argon atmosphere. After the irradiation
for 30 (1a) or 2 minutes (1c), 1H and 31P NMR spectra were
measured.
1Ar3P*
Ar•
(1)
(2)
Ar2P•
CH3X
+
Ar•
ArH (3)
•CH2X
+
+
DFT calculations were performed using the Gaussian
09, Revision A.02 program.[11] The IR spectra of 2c, 5cS,
and 5cS were simulated based on DFT B3LYP/6-31(G)
level of theory. The total energy of the alkyl radicals was
calculated based on DFT B3LYP/6-31+G(d,p) level of
theory.
•CH2X
Ar2P•
Ar2PCH2X
(3)
+
Ar2PH Ar2P-PAr2
15
4
1Ar3P*
hν
Ar2P•
Ar2PCH2X
•CH2X
Ar•
4.2
Photolysis in a large scale
|
Ar3P
A MeCN solution of 1c in a quartz test tube was irradiated
by light from a xenon lamp under an argon atmosphere. The
experiments were repeated 5 times (1c; 11.47 mg (MeCN;
13 mL), 10.35 (11), 10.66 (12), 10.47 (12), 10.56 (12),
53.51 mg (0.134 mmol) in 60 mL in total). The combined
1
CH3X
ArH
3
SCHEME 4 Supposed mechanism of the photoreaction of 1
under anaerobic

YASUI et Al.
7 of 8
|
reaction mixture was concentrated in vacuo, and the residue
was subjected to column chromatography using a mixture of
dichloromethane and hexane (1:1 (v/v)) as the eluent to give
2c (20 mg (46%)) as a white powder and 7c (8 mg (22%))
as a white solid. An AcOEt or MeCOMe solution of 1c was
likewise irradiated under the same conditions for 60 min-
utes. Immediately after the completion of the photolysis, S8
powder (ca. 100 mg) was added into the reaction mixture,
and the solution was stirred vigorously for several minutes.
Residual S8 powder was removed by filtration. The experi-
ments were repeated 5 times for the photolysis in each sol-
vent (In AcOEt; 1c; 10.51 mg (AcOEt; 10 mL), 10.41 (10),
10.54 (10), 10.99 (10), 10.41 (10), 52.86 mg (0.136 mmol)
in 50 mL in total. In MeCOMe; 1c; 11.67 mg (MeCOMe;
12 mL), 10.45 (10), 10.70 (10), 10.58 (10), 11.00 (10),
54.40 mg (0.140 mmol) in 52 mL in total). For the photoly-
sis in each solvent, the combined solution was concentrated
in vacuo, and the residue was subjected to column chroma-
tography using the same eluent as mentioned above to give
5cS (9 mg (17%)) as a while crystal from the photolysis in
AcOEt and 6cS (23 mg (46%)) as a while crystal from the
photolysis in MeCOMe.
4.2.4
Dimesityl(but-2-one-3-yl)phosphine
|
sulfide, Mes2P(=S)CH(CH3)C(=O)CH3 (7cS)
1H NMR (400 MHz, CDCl3) δ = 6.80 (d, 2H, J = 4.4 Hz,
ArH), δ = 6.76 (d, 2H, J = 4.0 Hz, ArH), δ = 4.17 (qui, 1H,
J = 6.8 Hz, CH), δ = 2.45 (s, 6H, ArCH3), δ = 2.33 (s, 6H,
ArCH3), δ = 2.23 (d, 6H, J = 4.8 Hz, ArCH3), δ = 1.92 (s,
3H, CO-CH3), δ = 6.80 (d, 2H, J = 4.4 Hz, ArH), δ = 1.77
(dd, 3H, J = 6.8, 12.8 Hz, CH-CH3), 13C NMR (100 MHz,
CDCl3) δ = 204.92, 142.15, 142.05, 141.19, 141.16, 139.95,
139.92, 138.82, 138.72, 132.22, 132.11, 131.74, 52.75,
52.38, 28.33, 23.68, 23.27, 20.81, 20.69, 14.97, 31P NMR
(161 MHz, CDCl3) δ = 43.14, MS (GC) m/z, Calcd for
372.17, found 372.
4.2.5
Dimesityl(2,2-dimethylbut-3-one-4-
|
yl)phosphine sulfide, Mes2P(=S)CH2C(=O)But
(8cS)
1H NMR (400 MHz, CDCl3) δ = 6.80 (d, 4H, J = 4.0 Hz,
ArH), δ = 4.10 (d, 2H, J = 12.8 Hz, CH2), δ = 2.41 (s,
12H, Ar-CH3), δ = 2.24 (s, 6H, Ar-CH3), δ = 1.11 (s, 9H,
C-CH3), 13C NMR (100 MHz, CDCl3) δ = 207.42, 140.05,
139.95, 131.73, 131.29, 130.49, 47.11, 46.60, 45.54, 26.31,
23.53, 20.79, 31P NMR (161 MHz, CDCl3) δ = 34.61, MS
(GC) m/z, Calcd for 400.20, found 400.
4.2.1
Dimesityl(cyanomethyl)phosphine,
|
Mes2PCH2CN (2c)
1H NMR (400 MHz, CDCl3) δ = 6.86 (d, 4H, J = 4.4 Hz,
ArH), δ = 3.80 (d, 2H, J = 12.4 Hz, P-CH2-), δ = 2.40
(s, 12H, Ar-CH3), δ = 2.27 (s, 6H, Ar-CH3), 31P NMR
(161 MHz, CDCl3) δ = −24.13, MS (EI+) m/z, Calcd for
C20H24NP: 309.16; Found; 309.0957. Anal. Calcd. for
C20H24NP: C, 77.64%, 7.82%, N, 4.53%, Found: C, 77.78%,
H, 7.54%, N, 4.41%. mp. 124.3~126.0°C.
4.2.6
Dimesityl(hydroxymethyl)phosphine
|
sulfide, Mes2P(=S)CH2OH (9cS)
1H NMR (400 MHz, CDCl3) δ = 6.82 (d, 4H, J = 4.4 Hz,
ArH), δ = 3.60 (d, 2H, J = 14.4 Hz, CH2), δ = 2.40 (s, 12H,
Ar-CH3), δ = 2.25 (s, 6H, Ar-CH3), 31P NMR (161 MHz,
CDCl3) δ = 83.96, MS (GC) m/z, Calcd for 332.13, found 332.
4.2.2
Dimesityl(carboethoxymethyl)
|
4.2.7
Tetramesityldiphosphine,
phosphine sulfide, Mes2P(=S)CH2C(=O)
OC2H5 (5cS)
|
Mes2PPMes2 (4c)
1H NMR (400 MHz, CDCl3): δ 2.18~2.39 (m, 36H, CH3),
6.63 (s, 4H, CH), 6.72~6.86 (m, 4H, CH), 31P NMR
(161 MHz, CDCl3): δ −30.0.
1H NMR (400 MHz, CDCl3) δ = 6.80 (d, 4H, J = 4.0 Hz,
ArH), δ = 3.91 (d, 2H, J = 14.0 Hz, P-CH2-), δ = 3.83
(q, 2H, J = 7.2 Hz, O-CH2-), δ = 2.39 (s, 12H, Ar-CH3),
δ = 2.24 (s, 6H, Ar-CH3), δ = 1.03 (t, 3H, J = 7.2 Hz, CH2-
CH3), 31P NMR (161 MHz, CDCl3) δ = 35.39, MS (EI+)
m/z, Calcd for C22H29O2PS: 388.16; Found; 388.
ORCID
Shinro Yasui
https://orcid.org/0000-0002-8752-9227
4.2.3
Dimesityl(acetylmethyl)phosphine
|
sulfide, Mes2P(=S)CH2C(=O)CH3 (6cS)
REFERENCES
1H NMR (400 MHz, CDCl3) δ = 6.81 (d, 4H, J = 4.0 Hz,
ArH), δ = 4.01 (d, 2H, J = 14.8 Hz, P-CH2-), δ = 2.39 (s,
12H, Ar-CH3), δ = 2.33 (s, 3H, CO-CH3), δ = 2.25 (s, 6H,
Ar-CH3), 31P NMR (161 MHz, CDCl3) δ = 32.31, MS (EI+)
m/z, Calcd for C21H27OPS: 358.15; Found; 358.04.
[1] a) S. Yasui, S. Tojo, T. Majima, J. Org. Chem. 2005, 70, 1276; b)
S. Yasui, S. Tojo, T. Majima, Org. Biomol. Chem. 2006, 4, 2969.
c) S. Yasui, S. Kobayashi, M. Mishima, J. Phys. Org. Chem. 2016,
29, 443. d) S. Yasui, S. Kobayashi, M. Mishima, Phosphorus
Sulfur Silicon 2016, 191, 1.

8 of 8
YASUI et Al.
|
[2] a) S. Yasui, Y. Ogawa, K. Shioji, S. Yamazaki, Chem. Lett. 2013,
42, 1478. b) S. Yasui, Y. Ogawa, K. Shioji, M. Mishima, S.
Yamazaki, Bull. Chem. Soc. Jpn. 2014, 87, 988.
Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin,
V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari,
A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi,
N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V.
Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski,
R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth,
P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O.
Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox,
Gaussian 09, Revision A.02, Gaussian, Inc., Wallingford CT
2009.
[3] S. Yasui, T. Ando, M. Ozaki, Y. Ogawa, K. Shioji, Phosphorus
Sulfur Silicon 2018, 193, 481.
[4] P. Braunstein, Chem. Rev. 2006, 106, 134.
[5] H. H. Karsch, G. Hanika, B. Huber, J. Riede, G. Müller, J.
Organometal Chem. 1989, 361, C25.
[6] W. MacFarlane, N. H. Rees, L. Constanza, M. Patel, I. J.
Colquhoun, J. Chem. Soc., Dalton Trans. 2000, 4453.
[7] To adjust the calculated wavenumbers with the observed ones,
the scaling factor 0.9613 was taken here. This value is re-
ported to be valid for gas phase at this level of theory. J. B.
Foresman, Æ. Frisch, in Exploring Chemistry with Electronic
Structure Methods, 2nd ed. Gaussian, Inc., Pittsburgh, PA
1996, Chapter 4.
SUPPORTING INFORMATION
Additional supporting information may be found online in
the Supporting Information section at the end of the article.
[8] a) Y. Sakaguchi, H. Hayashi, Chem. Phys. Lett. 1995, 245, 591; b)
Y. Sakaguchi, H. Hayashi, J. Phys. Chem. A 2004, 108, 3421.
[9] R. Zhang, Y. Zhou, Synthesis 1987, 10, 938.
How to cite this article: Yasui S, Ando T, Ozaki M,
Ogawa Y, Shioji K. A new method to prepare
functional phosphines through steady-state photolysis
of triarylphosphines. Heteroatom Chem. 2018;e21468.
https://doi.org/10.1002/hc.21468
[10] O. Dahl, F. K. Jensen, Acta Chem. Scand. B 1975, 29, 863.
[11] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B.
Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X.
Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J.
L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery Jr, J. E. Peralta, F.