Metal-Free Synthesis of Phenol-Aryl Selenides via Dehydrogenative C-Se Coupling of Aryl Selenoxides with Phenols

Article abstract of DOI:10.1021/acs.joc.0c00792

Herein, we disclose the synthesis of diaryl selenides through an unexpected C-Se coupling between aryl benzyl selenoxides and phenols. The synthetic significance of the method is that it provides a mild, rapid, and metal-free access to organoselenides in high yields with excellent functional group tolerance. This coupling of aryl benzyl selenoxides reveals a completely new reaction possibility compared with aryl sulfoxides. We also probed the reaction mechanism of this unexpected transformation through experimental studies and revealed a special Se(IV)-Se(III)-Se(II) reaction pathway.

Full text of DOI:10.1021/acs.joc.0c00792

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Article
Metal-free Synthesis of Phenol-Aryl Selenides via
Dehydrogenative C–Se Coupling of Aryl Selenoxides with Phenols
Zhengfen Liu, Yonggang Jiang, Chunxiang Liu, Linlin Zhang, Jing
Wang, Tiantian Li, Hongbin Zhang, Minyan Li, and Xiaodong Yang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.0c00792 • Publication Date (Web): 05 May 2020
Downloaded from pubs.acs.org on May 9, 2020
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Metal-free Synthesis of Phenol-Aryl Selenides via Dehydrogenative
C–Se Coupling of Aryl Selenoxides with Phenols
†
a
†a
†a
a
a
Zhengfen Liu, Yonggang Jiang, Chunxiang Liu, Linlin Zhang, Jing Wang,
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Tiantian Li, Hongbin Zhang, Minyan Li* and Xiaodong Yang,*
a
Key Laboratory of Medicinal Chemistry for Natural Resources, Ministry of Education and
Yunnan Province, School of Chemical Science and Technology, Yunnan University, Kunming,
6
50091, P. R. China. E-mail: xdyang@ynu.edu.cn; liminyan@sas.upenn.edu
b
Department of Soil and Water Science, Tropical Research and Education Center, University of
Florida, Homestead, 33031, FL (USA).
†Z. Liu & Y. Jiang & C. Liu contributed equally to this work.
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ABSTRACT
Herein, we disclose the synthesis of diaryl selenides through an unexpected C–Se coupling
between aryl benzyl selenoxides and phenols. The synthetic significance of the method is that it
provides a mild, rapid and metal-free access to organoselenides in high yields with excellent
functional group tolerance. This coupling of aryl benzyl selenoxides reveals a completely new
reaction possibility compared with aryl sulfoxides. We also probed the reaction mechanism of
this unexpected transformation through experimental studies and revealed a special Se(IV)-
Se(III)-Se(II) reaction pathway.
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INTRODUCTION
Diaryl chalcogenides (S, Se and Te) comprise an important subset of organochalcogenides and
have gained great attention in pharmaceutical and agrochemical industries due to their antiviral,
1
2
antioxidant and anticancer properties . In addition, they could also function as organocatalysts in
3
organic synthesis and as ionic liquid in material science. For years, synthetic organic chemists
keep looking for novel and efficient methodologies to construct diaryl chalcogenides. As
summarized in Scheme 1a, a widely employed approach is the direct coupling of S, Se and Te
4
precursors with aryl halides mediated by Pd, Ni, Ag, Cu, Fe catalysts. A greener transition-
metal-free approach to diaryl chalcogenides is the coupling of diaryldichalcogenides with aryl
coupling partners under oxidative coupling or nucleophilic aromatic substitution conditions
5
(
Scheme 1b). Although these reactions involve transition metals-free catalysis, they inevitably
relied on the use of large amounts of traditional oxidants, hence their selectivity and efficiency is
still room for improvement.
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Scheme 1 Synthesis of diaryl chalcogenides.
(a) Transition-metal catalyzed synthesis of diaryl chalcogenides
S
S
Ar
Ar
R1
Ar
Ar'
Ar'
Ar'
[
M] cat.
Ar' R2
+
Se
Te
Se
Te
R1
R1
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M = Pd, Ni, Ag, Cu, Fe Ar
Ar
Ar
1
2
R = Cl, Br,
SnBu3,
R = B(OH)2
Si(OMe)3
SnBu3
N2
SeAr
(b) Synthesis of diaryl chalcogenides by metal-free coupling
S
Ar
S
Ar
S
Ar
Ar
Ar
Ar'
Ar'
Ar'
I , K S O
8
2
2
2
Se
Te
Ar
Ar
Se
Te
+
Ar' R
Ar
Ar
Se
Te
or H PO2
3
R = B(OH)2
H
N BF
2
4
Recently, Lars Engman has extensive synthesized and studied these compounds as
antioxidants.6 In addition, tremendous effort has been devoted to the selective C-H
7
functionalization of phenols, especially the orthoselenylation of phenols. More recently, Yanagi
and Yorimitsu et al reported synthesis of sulfide bearing biaryl moieties by coupling aryl
8
9
10
sulfoxides with phenols and alkyl aryl sulfides. The reaction was believed to involve an
interrupted Pummerer reaction11 and a sulfonium-tethered sigmatropic rearrangement12
mechanism (Scheme 2a). On the basis of such unique transformation that converted sulfer (IV)
into sulfer (II), we sought to broaden this approach into other organochalcogenide family and
decided to study the coupling of aryl selenoxides with phenols (Scheme 2b). When diphenyl
selenoxide or methyl phenyl selenoxide was employed, only the reduction products of
selenoxides were found or trace diaryl products were obtained. To our surprise, instead of biaryl
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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product, we discovered that aryl benzyl selenoxides were converted to diaryl selenides (Scheme
c). Herein, we report an unexpected C–Se coupling between aryl selenoxides and phenols. Wide
varieties of aryl selenoxides and phenols could be coupled in high yields (37 examples, up to
9%) under a very mild and metal-free reaction conditions. This unexpected coupling of aryl
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selenoxides reveals a completely new reaction possibility compared with their sulfoxide
analogues. Mechanistic study was conducted to shed light on this unusual reactivity and revealed
a unique Se(IV)-Se(III)-Se(II) pathway.
Scheme 2 Synthesis of diaryl selenides.
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(
a) Coupling of aryl sulfoxides with phenols
R
S
via:
XH
SR
O
S
X
TFAA
R
+
XH
R = aryl or methyl X = S, O
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(
b) Our original design of coupling between aryl selenoxides and phenols
target:
via:
R
O
SeR
Se
OH
O
Se
TFAA
tBu
R
+
tBu
HO
R = aryl or methyl
tBu
(
c) Actual observation: C–Se coupling between aryl selenoxides and phenols
O
OH
Se
Se
TFAA
TFAA
tBu
99%
OH
Se
O
OH
OH
Se
Se
tBu
+
tBu
tBu
HO
11%
2
2%
OH
O
Se Ph
Se
TFAA
Se
Ph
+
tBu
tBu
tBu
99%
HO
Not observed
unexpected C–Se bond forming
RESULTS AND DISCUSSION
At the outset of this work, we hypothesized that the activation of aryl benzyl selenoxides plays
a crucial role in the reaction and hence decided to employ various activators using 1.5 equiv. of
phenyl benzyl selenoxide 1a and 2 equiv. 4-(tert-butyl)phenol 2b as coupling partners, DCM as
solvent at room temperature for 1 h. To our delight, as listed in Table 1, Entry 1, trifluoroacetic
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anhydride (TFAA) afforded the C–Se coupling product 3ab in 95% assay yield (AY, determined
1
after reaction workup by H NMR integration). Replacing TFAA to other activators including
trifluoromethanesulfonic anhydride (Tf O) (Entry 2), acetic anhydride (Ac O) (Entry 3), boron
2
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trifluoride etherate (BF ·OEt ) (Entry 4), propionic anhydride (Entry 5), phenylmaleic anhydride
3
2
(
Entry 6), Ms O (Entry 7) and TFA (Entry 8) generally showed lower activity, as demonstrated
2
by the low yields (9-70%, AY). Further, when the absence of the activator, the reaction did not
occur (Entry 9). Regarding solvent effect, when MeCN and MeNO were used, we observed that
2
yields dropped to 14% and 55%, respectively (Entries 10 and 11). Ethereal solvents THF, DME
and CPME (Entries 12-14) only afforded trace amount of product. We also tried a reaction at a
o
high temperature of about 110 C using 1,2-dichloroethane (1,2-DCE) as a high boiling point
solvent in the absence of an activator, but the test result was that the reaction didn't work (Entry
1
5). When TFAA (1.0 equiv, Entry 16) and 2b (1.5 equiv, Entry 17) was used, the yields
dropped to 51% and 77%, respectively. Further increasing the reaction concentration from 0.1 M
to 0.2 M led to an increase of yield to 97% (isolated yield, Entry 18). Notably, biaryl product was
not observed under all the reaction conditions listed in Table 1.
Table 1 Optimization of C–Se coupling between phenyl benzyl selenoxide 1a and 4-(tert-
butyl)phenol 2ba,b
O
tBu
OH
Se
HO
Se
Activator (1.5 equiv)
tBu
Solvent, Conc.
rt, 1 h
3
ab
1a
2b
Entry
Solvent
Activator
Conc. 2b (equiv) Yield of 3ab (%)a
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DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
TFAA
0.1 M
0.1 M
0.1 M
0.1 M
0.1 M
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Tf O
41
33
35
23
9
2
Ac O
2
1
1
1
1
1
1
1
1
1
1
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BF ·OEt
3
2
(CH CH CO) O
3
2
2
Phenylmaleic Anhydride 0.1 M
Ms O
0.1 M
0.1 M
70
12
2
TFA
＿
9
DCM
0.1 M
2.0
0
1
0
1
MeCN
MeNO2
THF
TFAA
TFAA
TFAA
TFAA
TFAA
0.1 M
0.1 M
0.1 M
0.1 M
0.1 M
2.0
2.0
2.0
2.0
2.0
14
55
6
1
12
1
1
3
4
DME
9
CPME
8
5c
6d
1,2-DCE
＿
0.1 M
2.0
0
1
1
DCM
DCM
DCM
TFAA
TFAA
TFAA
0.1 M
0.1 M
0.2 M
2.0
1.5
2.0
51
77
1
7
18
99(97)e
a
b
Reactions conducted on a 0.2 mmol scale using 1 equiv of 1a, and 2 equiv of 2b. Assay yield
1
determined by H NMR spectroscopy of the crude reaction mixture using CH Br as an internal
2
2
c
o
d
e
standard. 100 C. TFAA (1.0 equiv) was used. Isolated yield after chromatographic
purification.
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With the optimal conditions in hand (Table 1, entry 18), we studied the coupling of phenyl
benzyl selenoxide 1a with phenols bearing various substituents and substitution patterns (Table
0
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9
0
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4
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9
0
t
i
2
). Phenol 2a rendered product 3aa in 90% yield. For phenols bearing alkyl 4- Bu (2b), 4- Pr (2c)
and electro-donating (4-OMe, 2d) substituents, the yields were obtained in 97%, 63% and 43%
respectively. Substrates bearing the electron-withdrawing 4-Br, 4-I, 4-CN, 4-CF furnished the
3
products 3ae to 3ah in 68–99% yields. Carbonyl moieties were well tolerated, led to products 3ai
and 3aj in 93% and 85%, respectively. Phenols bearing 4-Ph (2k) and 4-Bpin (2l) were also good
coupling partners, leading to 3ak and 3al in 56% and 70% yields, respectively. Sterically
demanding 1-naphthol (2m) coupled with 1a to give product 3am in 62% yield. Interestingly, C–
Se coupling of 2-naphthol (2n), and 6-isoquinolinol (2o) exclusively occurred at the 1-position
and 5-position with excellent yield of 89% and 84%, respectively. Regarding phenols bearing
substituents at 2-position, 2-bromophenol (2p) underwent coupling in overall 93% yield with a
regioselectivity of 2.4:1 ortho/para to OH. Similarly, a mixture of 3.5:1 ortho and para coupling
products were isolated in the couping of 2-iodophenol (2q). The reason for the regioselectivity of
the substrates 2p and 2q may be due to the continuous electron transfer by both. For 3-
bromophenol (2r), a ratio of 2.9:1 was obartained for the C–Se coupling at 6 and 2 positions. The
reason why the products was a mixture may be the moderate sterical hinderance at the 2-position.
3
,5-dimethylphenol (2s) was efficiently coupled with 1a, afforded product 3as in 80% yield.
Finally, we also tried to apply this method to the extension to the some common diphenols.
Unfortunately, when catechol reacted with 1a, only the reduction product of selenoxide was
detected. However, resorcinol (2t) reacted with 1a led to the coupling product 3at in 85% yield.
Moreover, the more sterically hindered 1,1’-bi-2-naphthol (2u) underwent coupling with 1a in
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lower yield (12%). Compound 3ao was characterized by X-ray crystallography, confirming its
structure (CCDC 1902280, see Supporting Information for details).
1
1
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Table 2 Scope of phenolsa
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O
Se
OH
Se
TFAA (1.5 equiv)
R
HO
DCM (0.2 M)
R
1a
3aa-3au
2a-2u
rt, 1 h
Se
Se
tBu
Se
ipr
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7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
HO
aa 90%
HO
HO
b
3
3ab 97% (95%)
3ac 63%
Se
X
Se
X'
Se
OCH3
HO
HO
HO
c
3ae, X = Br, 68%
3af, X = I, 87%
3ag, X' = CN, 99%
ah, X' = CF , 93%
3
ad 43%
3
3
Se
Ph
Se
CHO
Bpin
Se
CO Me
2
HO
ak 56%
HO
ai 93%
HO
3
3aj 85%
3
Se
Se
Se
HO
al 70%
HO
HO
3
3am 62%
3an 89%
N
Se
Se
Br
OH
Se
HO
HO
3ap
3
ap
Br
9
3% (3ap:3ap' = 2.4:1)
3ao 84%
Br
Se
Se
Se
I
Se
HO
Br
HO
OH
HO
3ar
2% (3ar:3ar' = 2.9:1)
3aq
3aq
94% (3aq:3aq' = 3.5:1)
I
3ar
7
Ph
Se
OH
Se
Ph
Se
OH
OH
OH
HO
Se
Ph
3at 85%d
Se
Ph
3
as 80%
au 12%d
3
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Liu Page 11
aReactions conducted on 0.2 mmol scale using 1 equiv of 1a, and 2 equiv of aryl Phenols 2.
1
2
3
4
5
6
7
8
9
b
c
Isolated yield after chromatographic purification. Performed on 4.56 mmol scale. 4-
d
methoxyphenol (2d, 3 equiv), TFAA (3 equiv), stirred in oil bath for 5 h at 65 °C. 1 equiv of 2t
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
and 2u, 2.5 equiv of 1a, 3 equiv of TFAA.
Our protocol was also effective for a variesties of aryl benzyl selenoxides. As demonstrated in
t
Table 3, alkyl 4- Bu (1b) 3,5-dimethyl (1c) elctron-donating 4-OMe (1d) groups on the aryl site,
provided 3bb-3db in excellent 88%, 80% and 86% yields, respectively. The C–Se coupling of
selenoxides bearing electron-withdrawing substrates 4-Cl, 4-Br, 4-CF and 4-NO proceeded in
3
2
35-86% yields. Overall, the reaction rates of electron rich selenoxides were faster than those of
electron poor selenoxides. Sterically hindered 1-naphthyl benzylselenoxide 1i gave the coupling
product 3ia in good 68% yield. 4-biphenyl benzylselenoxide 1j was converted to 3ja in 64%
yield. In addition, when phenyl benzyl sulfoxide was employed, only trace diaryl products were
obtained. Tellurium-containing substrate, such as diphenyl ditelluride, did not lead to coupling
product under the standard conditions.
Table 3 Scope of aryl benzyl seleoxidesa
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
O
OH
tBu
TFAA (1.5 equiv)
Se
Se
+
R
R
tBu
DCM (0.2 M)
rt, 1 h
HO
1
b-1j
2
b
3bb-3ja
tBu
tBu
tBu
Se
tBu
Se
tBu
Se
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
tBu
HO
3bb 88%
HO
O
HO
db 86%
3cb 80%
3
tBu
Se
Se
tBu
Se
F3C
HO
Cl
HO
Br
HO
3fb 73%
3gb 65%
3
eb 86%
tBu
Se
tBu
Se
Se
O N
2
HO
Ph
HO
HO
ib 68%
3
hb 35%
3jb 64%
3
aReactions conducted on 0.2 mmol scale using 1 equiv of 1b-1j, and 2 equiv of 2b. Isolated yield
after chromatographic purification.
In addition, we accessed a series of N-heteroaryldiselenides by coupling 2-pyridyl benzyl
selenoxide 1k with different substituted phenols, applying the optimal conditions (Table 1, entry
13). As demonstrated in Table 4, coupling of 1k with phenol 2a led to product 3ka in 76% yield.
Additionally, substitution was well tolerated at the 4-position on the phenols (2b-2w), including
t
alkyl electron-donating groups 4- Bu (3kb, 86%), 4-Me (3kv, 84%), electron-withdrawing
groups 4-Br (3ke, 80%), 4-I (3kf, 64%) and carbonyl groups 4-CHO (3ki, 79%), 4-COCH3
(
3kw, 96%). Regarding 2-naphthol (2n), we observed that reaction exclusively occured at the C1
position. Similarly to 3ar in Table 2, a mixture of 2.7:1 regioselectivity (overall 89% yield) was
observed when 3-bromophenol 2r was coupled with 1k.
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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2
3
4
5
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9
Table 4 Synthesis of heteroaryl-containing diaryl selenidesa
O
Se
OH
TFAA (3 equiv)
Se
R
N
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
+
HO
DCM (0.2 M)
N
R
o
1k
3ka-3kw
6
5 C (oil bath), 5 h
2a-2w
tBu
Se
Se
Se
N
N
N
HO
HO
HO
b
3
kv 84%
3ka 76%
3kb 86%
Se
CHO
Se
I
Se
Br
N
N
N
HO
HO
HO
ke 80%
b
3kf 64%
3ki 79%
3
Br
Se
Se
Se
Se
COCH3
N
N
HO
Br
HO
N
N
HO
kn 91%
HO
3kw 96%
3kr
3kr'
3
89% (3kr:3kr' = 2.7:1)
aReactions conducted on 0.2 mmol scale using 1 equiv of 1k, and 3 equiv of aryl Phenols 2.
b
Isolated yield after chromatographic purification. Reaction conditions: 1k (0.2 mmol), 2b and 2f
(2 equiv), TFAA (1.5 equiv), rt, 1h.
To gain insight of this unexpected transformation, we carried out two preliminary mechanistic
investigations (Scheme 3). To probe the function of hydroxyl motif in the reaction, we coupled
the O-methylated analogue, anisole (2x) and 1-(tert-butyl)-4-methoxybenzene (2y) with 1a and
obtained products in excellent 97% and 96% yields, respectively. This result indicates that the
hydroxyl group of phenol does not participate in the reaction and rules out the possibility of
interrupted Pummerer reaction. On the other hand, when selenoxide 1l bearing 2-naphthylmethyl
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Liu Page 14
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
was employed for the reaction, naphthalen-2-yl methanol in 80% yield was isolated together with
the target product 3ab in 84% yield, which was similar to the formation of benzyl alcohol for
above example.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 3 Mechanistic study.
(a)
Se
R
O
OMe
TFAA (1.5 equiv)
Se
MeO
R
DCM (0.2 M)
rt, 1 h
1a
2x, R = H
3ax, R = H, 97%
t
t
2
y, R = Bu
3ay, R = Bu, 96%
Se
tBu
(b)
O
HO
OH
TFAA (1.5 equiv)
Se
3
ab, 84%
tBu
DCM (0.2 M)
rt, 1 h
+
1l
2b
HO
80%
While the exact mechanism remains unclear at the current stage, based on the above
mechanistic study and the interrupted Pummerer reaction machanism in the coupling of
sulfoxides with phenols, we propose the mechanism for the C–Se coupling in Scheme 4. We
envision that the selenium ion A is firstly formed from the activation of selenoxide 1a with
–
TFAA, this process releases one equiv. of TFAO . Based on the result of 1-(tert-butyl)-4-
methoxybenzene (Scheme 3a), we hypothesize that the A is a reactive electrophile and would
undergo electrophilic substitution with phenol 2a to form the dearomatized intermediate B. Next,
rearomatization provides a Se(III) intermediate C and eliminates one equiv. of TFA. Notably,
intermediate C in the reaction mixture was detected by high resolution mass spectrometry (See
supporting information for detail). In light of the observation of naphthalen-2-ylmethanol in
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Liu Page 15
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2
3
4
5
6
7
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9
–
Scheme 3b, we propose that C would be captured by the TFAO , eliminate the PhCH OTFA and
2
yield the final product 3ab.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Scheme 4 Proposed reaction mechanism.
O
O
F3C
O
CF3
TFAA
tBu
O
OCOCF3
Se
Se
Ph
1a
Ph
HO
A
2a
O
OH
Se
O
CF3
TFAO
3ab
tBu
B
Ph
OCOCF3
Se
H
OH
Ph
OCOCF3
tBu
Ph
Se
OH
HOCOCF3
C
tBu
mass detected by HRMS
+
+
C H OSe , found 397.1072 [M]
2
3 25
CONCLUSION
In summary, we uncover a unique metal-free coupling strategy that forms diaryl selenides
through the C–Se coupling between aryl/heteroaryl benzyl selenoxides and phenols without
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
ACS Paragon Plus Environment

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Page 16 of 52
Liu Page 16
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
traditional strong oxidants. Synthetically, a wide range of diaryl selenides are obtained with great
functional groups tolerance in good to excellent yields. Under the same reaction conditions, the
reactivity of selenide is much lower than that of sulfide. However, they are also affected by
functional groups, when aryl benzyl selenoxides reacted with phenols, the C–Se coupling
reverses the normal pattern of interrupted Pummerer reaction and allows access to the diaryl
selenides instead of biaryls. Based on experimental observation and mass spectrometry study, we
rationalize that this transformation proceed with a Se(IV)-Se(III)-Se(II) route involving
electrophilic substitution and fragmentation.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
EXPERIMENTAL SECTION
General Information. All air- and moisture-sensitive solutions and chemicals were handled
under a nitrogen atmosphere of a glovebox and solutions were transferred via “Titan” brand
pipettor. Anhydrous solvents, including DCM (dichloromethane) ， DME (dimethoxyethane),
CPME (cyclopentyl methyl ether), THF (tetrahydrofuran), toluene, acetonitrile, and
nitromethane were purchased from Sigma-Aldrich and used without further purification. Unless
otherwise stated, all reagents were commercially available and used as received without further
purification. Chemicals were obtained from Sigma-Aldrich, Acros, TCI and Alfa-Aesar. TLC
was performed with Merck TLC Silica gel60 F254 plates with detection under UV light at 254
nm. Silica gel (200-300 mesh, Qingdao) was used for flash chromatography. Proton nuclear
1
magnetic resonance ( H-NMR) spectra were recorded on a Bruker Avance 300 & Bruker DRX
4
00 & Bruker DRX 600 spectrometer at 300 & 400 & 600 MHz. Carbon-13 nuclear magnetic
1
3
resonance ( C-NMR) was recorded on Bruker Avance 300 & Bruker DRX 400 & Bruker DRX
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 17 of 52
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Liu Page 17
00 spectrometer at 75 & 100 & 150 MHz. Chemical shifts are reported as δ values in parts per
million (ppm) relative to tetramethylsilane (TMS) for all recorded NMR spectra. The infrared
1
2
3
4
5
6
7
8
9
6
−
1
(IR) spectra were measured on a Nicolet iS10 FTIR spectrometer with 4 cm resolution and 32
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
−1
−1
scans between wavenumber of 4000 cm and 400 cm . High Resolution Mass spectra were
taken on AB QSTAR Pulsar mass spectrometer. Melting points were obtained on a XT-4
melting-point apparatus and were uncorrected.
Preparation of Symmetrical Diselenides. Symmetrical diselenides were prepared according
to literature procedures.13
Preparation of Aryl Benzyl Selenides. Aryl benzyl selenides were prepared according to
literature procedures.1g
General Procedure and characterization for the Preparation of Aryl Benzyl Selenoxides.
Aryl benzyl selenoxides (1a-1l) were prepared according to literature procedures.1g
(benzylseleninyl)benzene (1a). The reaction was performed following the literature
1g
procedures with benzyl(phenyl)selane (247.2 mg, 1 mmol) and N-Chlorosuccinimide (160.2
mg, 1.2 mmol). The crude material was recrystallized from hexanes/CH Cl (4:1) to give the
2
2
1
13
1
product 1a (256 mg, 98%) as a white solid. The H and C{ H} data for this compound match
the literature data.1g
1
-(benzylseleninyl)-4-(tert-butyl)benzene (1b). The reaction was performed following the
literature procedures1g with benzyl(4-(tert-butyl)phenyl)selane (303.3 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1b (306 mg,
1
9
6% yield) as a white solid. m.p. = 107 – 108 °C; R = 0.57 (EtOAc:methanol = 6:1); H NMR
f
(400 MHz, Chloroform-d) δ 7.44 – 7.35 (m, 2H), 7.32 – 7.25 (m, 2H), 7.21 – 7.14 (m, 3H), 6.90
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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The Journal of Organic Chemistry
Page 18 of 52
Liu Page 18
dt, J = 7.6, 1.2 Hz, 2H), 4.10 (d, J = 11.2 Hz, 1H), 3.89 (d, J = 11.2 Hz, 1H), 1.26 (s, 9H) ppm;
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
1
3
1
C{ H} NMR (100 MHz, Chloroform-d) δ 155.1, 136.4, 130.1, 129.8, 128.5, 128.2, 126.3,
125.9, 59.3, 35.0, 31.2 ppm; IR (thin film): 3060, 3027, 2962, 1629, 1492, 1454, 1391, 1361,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
-1
+
1
265, 1173, 1105, 1065, 1012, 816, 758, 723 cm ; HRMS (ESI-TOF) m/z: [M+H] Calcd for
C H OSe 321.0752; Found 321.0754.
1
7
21
1
-(benzylseleninyl)-3,5-dimethylbenzene (1c). The reaction was performed following the
literature procedures1g with benzyl(3,5-dimethylphenyl)selane (275.3 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1c (277 mg,
1
95% yield) as a white solid. m.p. = 96 – 97 °C; R = 0.56 (EtOAc:methanol = 6:1); H NMR (400
f
MHz, Chloroform-d) δ 7.32 – 7.24 (m, 3H), 7.10 (s, 1H), 6.98 (d, J = 5.2 Hz, 4H), 4.17 (d, J =
1
1
1.2 Hz, 1H), 3.93 (d, J = 11.2 Hz, 1H), 2.31 (s, 6H) ppm; 13C{ H} NMR (100 MHz,
Chloroform-d) δ 139.2, 133.0, 130.0, 129.9, 128.5, 128.2, 123.5, 59.2, 21.2 ppm; IR (thin film):
-1
3
058, 2976, 1601, 1493, 1452, 1434, 1174, 1066, 861, 842, 697 cm ; HRMS (ESI-TOF) m/z:
+
[
M+H] Calcd for C H OSe 293.0439; Found 293.0437.
1
5
17
1
-(benzylseleninyl)-4-methoxybenzene (1d). The reaction was performed following the
literature procedures1g with benzyl(4-methoxyphenyl)selane (277.2 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1d (276 mg,
1
13
1
94% yield) as a white solid. The H and C{ H} data for this compound match the literature
data.1g
1
-(benzylseleninyl)-4-chlorobenzene (1e). The reaction was performed following the literature
1g
procedures with benzyl(4-chlorophenyl)selane (281.6 mg, 1 mmol) and N-Chlorosuccinimide
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 19 of 52
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2
3
4
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(
160.2 mg, 1.2 mmol). The crude material was purified by flash chromatography on silica gel
(
eluted with EtOAc→methanol) to give the product 1e (273.8 mg, 92% yield) as a white solid.
1
m.p. = 132 – 133 °C; R = 0.46 (EtOAc:methanol = 6:1); H NMR (400 MHz, Chloroform-d) δ
f
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
7
1
1
1
.37 – 7.30 (m, 2H), 7.28 – 7.17 (m, 5H), 6.88 (dd, J = 7.6, 2.0 Hz, 2H), 4.14 (d, J = 11.2 Hz,
1
3
1
H), 3.87 (d, J = 11.2 Hz, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 137.8, 129.9,
29.4, 129.3, 128.7, 128.5, 127.6, 59.1 ppm; IR (thin film): 3058, 3029, 2973, 2919, 1493, 1473,
-1
+
457, 1387, 1084, 1029, 820, 761, 729, 699 cm ; HRMS (ESI-TOF) m/z: [M+H] Calcd for
C H ClOSe 298.9736; Found 298.9734.
1
3
12
1
-(benzylseleninyl)-4-bromobenzene (1f). The reaction was performed following the literature
1g
procedures with benzyl(4-bromophenyl)selane (326.1 mg, 1 mmol) and N-Chlorosuccinimide
(160.2 mg, 1.2 mmol). The crude material was purified by flash chromatography on silica gel
(eluted with EtOAc→methanol = 5:1) to give the product 1f (308.0 mg, 90% yield) as a white
1
solid. m.p. = 143 – 144 °C; R = 0.51 (EtOAc:methanol = 6:1); H NMR (400 MHz, Chloroform-
f
d) δ 7.56 – 7.44 (m, 2H), 7.29 – 7.12 (m, 5H), 6.96 – 6.79 (m, 2H), 4.13 (d, J = 11.2 Hz, 1H),
1
3
1
3
1
1
.86 (d, J = 11.6 Hz, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 138.5, 132.3, 129.9,
29.3, 128.7, 128.5, 127.7, 126.1, 59.1 ppm; IR (thin film): 2964, 2918, 1629, 1564, 1493, 1477,
-1
+
456, 1382, 1172, 1088, 1007, 820, 761, 707,697 cm ; HRMS (ESI-TOF) m/z: [M+H] Calcd
for C H BrOSe 342.9231; Found 342.9235.
1
3
12
1
-(benzylseleninyl)-4-(trifluoromethyl)benzene (1g). The reaction was performed following the
1
g
literature procedures with benzyl(4-(trifluoromethyl)phenyl)selane (315.0 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1g (305.0 mg,
1
92% yield) as a white solid. m.p. = 132 – 133 °C; R = 0.52 (EtOAc:methanol = 6:1); H NMR
f
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 20 of 52
Liu Page 20
400 MHz, Chloroform-d) δ 7.70 (d, J = 7.6 Hz, 2H), 7.53 (d, J = 8.0 Hz, 2H), 6.34 – 6.26 (m,
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
1
3
1
3
H), 6.96 (d, J = 7.2 Hz, 2H), 4.25 (d, J = 11.2 Hz, 1H), 3.99 (d, J = 11.2 Hz, 1H) ppm; C{ H}
NMR (100 MHz, Chloroform-d) δ 143.9, 133.5 (q, JC-F = 32.6 Hz), 130.7, 129.8, 129.1, 128.7,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
28.6, 126.7, 126.0 (q, JC-F = 3.8 Hz), 123.5 (q, JC-F = 271 Hz), 59.1 ppm; IR (thin film): 2978,
-1
2
921, 1596, 1494, 1397, 1327, 1168, 1114, 1100, 1068, 1052, 1012, 852, 820, 761, 698 cm ;
+
HRMS (ESI-TOF) m/z: [M+H] Calcd for C H F OSe 333.0000; Found 333.0003.
14 12
3
1
-(benzylseleninyl)-4-nitrobenzene (1h). The reaction was performed following the literature
1
g
procedures with benzyl(4-nitrophenyl)selane (292.2 mg, 1 mmol) and N-Chlorosuccinimide
(160.2 mg, 1.2 mmol). The crude material was purified by flash chromatography on silica gel
(eluted with EtOAc→methanol = 5:1) to give the product 1h (287.0 mg, 92% yield) as a yellow
1
solid. m.p. = 143 – 144 °C; R = 0.57 (EtOAc:methanol = 6:1); H NMR (400 MHz, Chloroform-
f
d) δ 8.33 – 8.20 (m, 2H), 7.64 – 7.50 (m, 2H), 7.35 – 7.25 (m, 3H), 7.04 – 6.87 (m, 2H), 4.29 (d,
1
3
1
J = 11.2 Hz, 1H), 4.01 (d, J = 11.2 Hz, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ
1
2
49.9, 147.1, 129.8, 128.8, 128.8, 128.8, 127.4, 123.9, 59.1 ppm; IR (thin film): 3091, 2969,
-1
918, 1599, 1520, 1492, 1453, 1347, 1312, 1101, 1010, 851, 816, 737, 702 cm ; HRMS (ESI-
+
TOF) m/z: [M+H] Calcd for C H NO Se 309.9979; Found 309.9977.
13 12
3
1
-(benzylseleninyl)naphthalene (1i). The reaction was performed following the literature
1g
procedures with benzyl(naphthalen-1-yl)selane (297.0 mg, 1 mmol) and N-Chlorosuccinimide
160.2 mg, 1.2 mmol). The crude material was purified by flash chromatography on silica gel
(
(eluted with EtOAc→methanol) to give the product 1i (304.0 mg, 97% yield) as a white solid.
1
m.p. = 103 – 104 °C; R = 0.56 (EtOAc:methanol = 6:1); H NMR (400 MHz, Chloroform-d) δ
f
7
.96 (dd, J = 8.0, 4.8 Hz, 2H), 7.90 (dd, J = 7.2, 1.2 Hz, 1H), 7.67 (d, J = 8.0 Hz, 1H), 7.61 –
7.53 (m, 2H), 7.50 (ddd, J = 8.4, 6.8, 1.2 Hz, 1H), 7.23 – 7.16 (m, 1H), 7.15 – 7.07 (m, 2H), 6.83
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Liu Page 21
1
2
3
4
5
6
7
8
9
13
1
(
d, J = 6.8 Hz, 2H), 4.20 (d, J = 11.2 Hz, 1H), 4.16 (d, J = 11.2 Hz, 1H) ppm; C{ H} NMR
(
100 MHz, Chloroform-d) δ 136.8, 133.5, 131.3, 131.1, 129.9, 129.7, 129.1, 128.4, 128.1, 127.2,
126.5, 125.8, 124.9, 122.2, 57.8 ppm; IR (thin film): 3077, 3024, 2981, 1599, 1501, 1492, 1453,
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
-1
+
1
371, 1340, 1252, 1058, 1017, 849, 825, 728, 694 cm ; HRMS (ESI-TOF) m/z: [M+H] Calcd
for C H OSe 315.0284; Found 315.0283.
1
7
15
4
-(benzylseleninyl)-1,1'-biphenyl (1j). The reaction was performed following the literature
procedures1g with [1,1'-biphenyl]-4-yl(benzyl)selane (323.3 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1j (329 mg,
1
97% yield) as a white solid. m.p. = 159 – 160 °C; R = 0.63 (EtOAc:methanol = 6:1); H NMR
f
(
400 MHz, Chloroform-d) δ 7.73 – 7.65 (m, 2H), 7.62 (d, J = 8.0 Hz, 2H), 7.52 – 7.48 (m, 4H),
7
.46 – 7.39 (m, 1H), 7.32 – 7.26 (m, 3H), 7.02 (d, J = 8.0 Hz, 2H), 4.25 (d, J = 11.2 Hz, 1H),
1
3
1
4.02 (d, J = 11.2 Hz, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 144.4, 139.7, 129.9,
1
2
29.8, 129.0, 128.7, 128.3, 128.2, 127.9, 127.2, 126.6, 59.3 ppm; IR (thin film): 3056, 3027,
-1
964, 1630, 1492, 1477, 1452, 1389,1065, 1004, 831, 816, 755, 694 cm ; HRMS (ESI-TOF)
+
m/z: [M+H] Calcd for C H OSe 341.0441; Found 341.0439.
19 17
2
-(benzylseleninyl)pyridine (1k). The reaction was performed following the literature
procedures1g with 2-(benzylselanyl)pyridine (248.2 mg, 1 mmol) and N-Chlorosuccinimide
(
160.2 mg, 1.2 mmol). The crude material was purified by flash chromatography on silica gel
(eluted with EtOAc→methanol) to give the product 1k (219 mg, 83% yield) as a colorless oil. Rf
1
=
0.36 (EtOAc:methanol = 3:1); H NMR (300 MHz, Chloroform-d) δ 8.56 (dd, J = 11.1, 1.8 Hz,
1
H), 7.69 (td, J = 7.5, 1.8 Hz, 1H), 7.59 (dt, J = 7.8, 0.9 Hz, 1H), 7.29 (ddd, J = 7.5, 4.8, 1.5 Hz,
1H), 7.20 – 7.07 (m, 3H), 7.00 – 6.83 (m, 2H), 4.19 (d, J = 11.4 Hz, 1H), 4.02 (d, J = 11.7 Hz,
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 22 of 52
Liu Page 22
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2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
13
1
1
H) ppm; C{ H} NMR (75 MHz, Chloroform-d) δ 162.7, 149.7, 137.8, 130.0, 129.8, 128.4,
1
28.1, 125.1, 121.7, 56.4 ppm; IR (thin film): 3060, 3028, 2934, 1652, 1599, 1572, 1557, 1539,
-1
1494, 1451, 1412, 1277, 1218, 1180, 1148, 1108, 1082, 985, 755, 698 cm ; HRMS (ESI-TOF)
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
+
m/z: [M+H] Calcd for C H NOSe 266.0079; Found 266.0081.
1
2
12
2
-((phenylseleninyl)methyl)naphthalene (1l). The reaction was performed following the
1
g
literature procedures with (naphthalen-2-ylmethyl)(phenyl)selane (297.3 mg, 1 mmol) and N-
Chlorosuccinimide (160.2 mg, 1.2 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc→methanol) to give the product 1l (300.7 mg,
1
9
6% yield) as a white solid. m.p. = 158 – 159 °C; R = 0.53 (EtOAc:methanol = 6:1); H NMR
f
(600 MHz, Chloroform-d) δ 7.95 (dd, J = 8.4, 4.8 Hz, 2H), 7.90 (dd, J = 7.2, 1.2 Hz, 1H), 7.67
d, J = 8.4 Hz, 1H), 7.56 (t, J = 7.2 Hz, 2H), 7.49 (ddd, J = 8.4, 6.6, 1.2 Hz, 1H), 7.19 (t, J = 7.2
Hz, 1H), 7.10 (t, J = 7.8 Hz, 2H), 6.83 (dd, J = 7.8, 1.2 Hz, 2H), 4.18 (d, J = 11.4 Hz, 1H), 4.15
(
1
3
1
(d, J = 11.4 Hz, 1H) ppm; C{ H} NMR (150 MHz, Chloroform-d) δ 136.9, 133.5, 131.2, 131.1,
1
3
30.0, 129.7, 129.0, 128.3, 128.1, 127.2, 126.5, 125.8, 125.0, 122.2, 57.8 ppm; IR (thin film):
-1
059, 3024, 2981, 1599, 1501, 1453, 1371, 1253, 1058, 921, 849, 825, 791, 728 cm ; HRMS
+
(
ESI-TOF) m/z: [M+H] Calcd for C H OSe 315.0283; Found 315.0283.
17 15
General Procedure and characterization for the C–Se Coupling of Aryl Selenoxides with
Phenols.
General Procedure A (Table 2 and Table 3). Synthesis of 3ab is representative. An oven-
dried 8 mL reaction vial equipped with a stir bar was charged with phenyl benzyl selenoxide 1a
52.6 mg, 0.2 mmol) and 4-tert-butylphenol 2b (60.1mg, 0.4 mmol) under a nitrogen atmosphere
in a glove box. Anhydrous CH Cl (1.0 mL) was added by a “Titan” brand 1000 μL pipettor to
(
2
2
the reaction vial and the reaction vial was added trifluoroacetic anhydride (42.0 μL, 0.3 mmol)
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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by a “Titan” brand 100 μL pipettor. Then the vial was sealed with a cap, removed from the glove
box, and stirred for 1 h at room temperature. The reaction mixture was opened to air, saturated
aqueous 1 mL NaHCO was added and the resulting biphasic solution was extracted with CH Cl
3
2
2
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(
15 mL×3). The combined organic layer was washed with brine, dried over Na SO , and
2 4
concentrated under reduced pressure. The crude material was loaded onto a silica gel column and
purified by flash chromatography.
General Procedure B (Table 4). Synthesis of 3ka is representative. An oven-dried 10 mL
sealed tube equipped with a stir bar was charged with 2-(benzylseleninyl)pyridine 1k (52.8 mg,
0
.2 mmol) and phenol 2a (56.5mg, 0.6 mmol) under a nitrogen atmosphere in a glove box.
Anhydrous CH Cl (1.0 mL) was added by a “Titan” brand 1000 μL pipettor to the reaction vial
2
2
and the reaction vial was added trifluoroacetic anhydride (83.5 μL, 0.6 mmol) by a “Titan” brand
00 μL pipettor. Then the vial was sealed with a cap, removed from the glove box, and stirred in
1
oil bath for 5 h at 65 °C. The reaction mixture was opened to air, saturated aqueous 1mL
NaHCO was added and the resulting biphasic solution was extracted with CH Cl (15 mL×3).
3
2
2
The combined organic layer was washed with brine, dried over Na SO , and concentrated under
2
4
reduced pressure. The crude material was loaded onto a silica gel column and purified by flash
chromatography.
2
-(phenylselanyl)phenol (3aa). The reaction was performed following the General Procedure
A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and phenol 2a (37.7 mg, 0.4 mmol).
The crude material was purified by flash chromatography on silica gel (eluted with
EtOAc:hexanes = 1:20) to give the product 3aa (44.9 mg, 90% yield) as a colorless oil. R = 0.47
f
1
(EtOAc:hexanes = 1:10); H NMR (300 MHz, Chloroform-d) δ 7.56 (dd, J = 7.8, 1.5 Hz, 1H),
7.32 – 7.25 (m, 1H), 7.16 – 7.09 (m, 5H), 7.00 (dd, J = 8.1, 1.2 Hz, 1H), 6.82 (td, J = 7.5, 1.2 Hz,
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 24 of 52
Liu Page 24
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
13
1
1
H), 6.36 (s, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 155.6, 136.9, 131.2, 129.7,
1
28.6, 128.4, 125.7, 120.3, 114.1, 113 ppm; IR (thin film): 3414, 3070, 2918, 2849, 1577, 1476,
-
1
-
1467, 1337, 1288, 1257, 1187, 1021, 827, 754, 688 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
13
1
for C H OSe 248.9824; Found 248.9824. The H and C{ H} data for this compound match the
1
2
9
literature data.14
-(tert-butyl)-2-(phenylselanyl)phenol (3ab). The reaction was performed following the
4
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-tert-
butylphenol 2b (60.1 mg, 0.4 mmol). The crude material was purified by flash chromatography
on silica gel (eluted with EtOAc:hexanes = 1:20) to give the product 3ab (59.2 mg, 97% yield)
1
as a yellow oil. R = 0.56 (EtOAc:hexanes = 1:10); H NMR (400 MHz, Chloroform-d) δ 7.54
f
(
dd, J = 2.4, 1.6 Hz, 1H), 7.28 (ddd, J = 8.8, 2.8, 1.2 Hz, 1H), 7.13 – 7.04 (m, 5H), 6.92 (dd, J =
1
3
1
8
.4, 1.2 Hz, 1H), 6.17 (d, J = 2.0 Hz, 1H), 1.20 (d, J = 1.6 Hz, 9H) ppm; C{ H} NMR (100
MHz, Chloroform-d) δ 154.5, 144.3, 134.7, 131.1, 129.5, 129.4, 129.4, 126.7, 114.6, 114.0, 34.2,
3
8
3
1.6 ppm; IR (thin film): 3429, 2961, 1516, 1497, 1484, 1394, 1285, 1266, 1210, 1186, 1022,
-
1
-
89, 734, 688 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd for C H OSe 305.0450; Found
1
6
17
1
13
1
14
05.0449. The H and C{ H} data for this compound match the literature data.
-isopropyl-2-(phenylselanyl)phenol (3ac). The reaction was performed following the General
Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-isopropylphenol 2c
54.5 mg, 0.4 mmol). The crude material was purified by flash chromatography on silica gel
4
(
(eluted with EtOAc:hexanes = 1:20) to give the product 3ac (36.7 mg, 63% yield) as a colorless
1
oil. R = 0.51 (EtOAc:hexanes = 1:10); H NMR (400 MHz, Chloroform-d) δ 7.48 (d, J = 2.0 Hz,
f
1
H), 7.29 – 7.11 (m, 6H), 7.00 (d, J = 8.4 Hz, 1H), 6.26 (s, 1H), 2.90 – 2.79 (m, 1H), 1.22 (d, J =
1
3
1
6.8 Hz, 6H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 154.8, 141.9, 135.6, 131.1, 130.4,
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 25 of 52
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29.5, 129.4, 126.7, 114.9, 114.2, 33.2, 24.2 ppm; IR (thin film): 3424, 2959, 1577, 1478, 1383,
1
2
3
4
5
6
7
8
9
1
1
-1
-
276, 1247, 1189, 1022, 999, 888, 734, 689 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd for
C H OSe 291.03; Found 291.0301.
1
5
15
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
4
-methoxy-2-(phenylselanyl)phenol (3ad). The reaction was performed following the General
Procedure B with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-methoxyphenol 2d
(
49.7 mg, 0.4 mmol). The crude material was purified by flash chromatography on silica gel
(
eluted with EtOAc:hexanes = 1:20) to give the product 3ad (24.0 mg, 43% yield) as a yellow
1
oil. R = 0.44 (EtOAc:hexanes = 1:5); H NMR (400 MHz, Chloroform-d) δ 7.26 – 7.19 (m,
f
5
H), 7.16 (d, J = 3.2 Hz, 1H), 7.01 (d, J = 9.2 Hz, 1H), 6.93 (dd, J = 8.8, 3.2 Hz, 1H), 6.03 (s,
1
3
1
1H), 3.75 (s, 3H) ppm; C{ H} (100 MHz, Chloroform-d) δ 153.4, 150.8, 130.7, 129.72, 129.5,
1
1
26.9, 121.6, 118.5, 115.5, 114.6, 55.9 ppm; IR (thin film): 3424, 2999, 1577，1483, 1438,
-1
-
334, 1276, 1220, 1040, 1022, 999, 913, 772, 689 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd
for C H O Se 278.993; Found 278.9934.
1
3
11
2
4
-bromo-2-(phenylselanyl)phenol (3ae). The reaction was performed following the General
Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-bromophenol 2e (69.2
mg, 0.4 mmol). The crude material was purified by flash chromatography on silica gel (eluted
with EtOAc:hexanes = 1:15) to give the product 3ae (44.6 mg, 68% yield) as a yellow oil. R =
f
1
0
.38 (EtOAc:hexanes = 1:5); H NMR (400 MHz, Chloroform-d) δ 7.74 (d, J = 2.4 Hz, 1H), 7.41
(dd, J = 8.8, 2.4 Hz, 1H), 7.28 – 7.16 (m, 5H), 6.94 (d, J = 8.8 Hz, 1H), 6.40 (s, 1H) ppm;
13
1
C{ H} NMR (100 MHz, Chloroform-d) δ 155.8, 139.4, 134.9, 130.2, 130.0, 129.7, 127.3,
16.9, 116.8, 112.4 ppm; IR (thin film): 3411, 3071, 1576, 1476, 1465, 1438, 1324, 1275, 1237,
1
1
-1
-
188, 1071, 1021, 819, 734, 687, 623 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd for
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 26 of 52
Liu Page 26
C H BrOSe 326.8929; Found 326.8932. The H and C{ H} data for this compound match the
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
13
1
1
2
8
literature data.15
4-iodo-2-(phenylselanyl)phenol (3af): The reaction was performed following the General
Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-iodophenol 2f (88.0
mg, 0.4 mmol). The crude material was purified by flash chromatography on silica gel (eluted
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
with EtOAc:hexanes = 1:15) to give the product 3af (65.3 mg, 87% yield) as a white solid. m.p.
1
=
=
57 – 58 °C; R = 0.44 (EtOAc:hexanes = 1:5); H NMR (400 MHz, Chloroform-d) δ 7.93 (d, J
f
2.0 Hz, 1H), 7.60 (dd, J = 8.8, 2.4 Hz, 1H), 7.27 – 7.19 (m, 5H), 6.84 (d, J = 8.4 Hz, 1H), 6.41
1
3
1
(
s, 1H). ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 156.5, 145.3, 140.8, 130.0, 129.7,
127.3, 117.4, 82.2 ppm; IR (thin film): 3407, 3070, 2922, 2850, 1576, 1561, 1460, 1274, 1186,
-1
-
1
3
021, 998, 946, 880, 734, 687, 607 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd for C H IOSe
12 8
74.8791; Found 374.8791.
4-hydroxy-3-(phenylselanyl)benzonitrile (3ag). The reaction was performed following the
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-
hydroxybenzonitrile 2g (47.7 mg, 0.4 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc:hexanes = 1:6) to give the product 3ag (51.0
1
mg, 93% yield) as a white solid. m.p. = 137 – 138 °C; R = 0.36 (EtOAc:hexanes = 1:2); H
f
NMR (300 MHz, Chloroform-d) δ 7.92 (d, J = 2.1 Hz, 1H), 7.61 (dd, J = 8.7, 2.1 Hz, 1H), 7.31 –
1
3
1
7
.24 (m, 5H), 7.11 (d, J = 8.4 Hz, 1H), 6.92 (s, 1H) ppm; C{ H} NMR (75 MHz, Chloroform-
d) δ 160.0, 141.3, 135.7, 130.9, 129.9, 128.9, 127.9, 118.2, 117.2, 116.0, 104.9 ppm; IR (thin
-1
film): 3284, 2927, 2228, 1592, 1477, 1401, 1289, 1219, 1178, 1022, 824, 772, 689 cm ; HRMS
+
(
ESI-TOF) m/z: [M+Na] Calcd for C H NNaOSe 297.9742; Found 297.9742.
1
3
9
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 27 of 52
The Journal of Organic Chemistry
Liu Page 27
-(phenylselanyl)-4-(trifluoromethyl)phenol (3ah). The reaction was performed following the
1
2
3
4
5
6
7
8
9
2
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-
(trifluoromethyl)phenol 2h (64.8 mg, 0.4 mmol). The crude material was purified by flash
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
chromatography on silica gel (eluted with EtOAc:hexanes = 1:15) to give the product 3ah (62.8
1
mg, 99% yield) as a colorless oil. R = 0.33 (EtOAc:hexanes = 1:5); H NMR (400 MHz,
f
Chloroform-d) δ 7.92 (d, J = 2.4 Hz, 1H), 7.60 (dd, J = 8.4, 2.0 Hz, 1H), 7.26 – 7.22 (m, 5H),
1
3
1
7
1
.14 (d, J = 8.8 Hz, 1H), 6.75 (s, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 159.4,
35.0, 135.1 (q, JC-F = 3.6 Hz), 130.2 , 129.9, 129.7, 129.5 (q, JC-F = 3.6 Hz), 127.6, 123.9 (q, JC-F
=
280 Hz), 123.7 (q, JC-F = 32.0 Hz), 115.7, 115.5 ppm; IR (thin film): 3404, 3073, 2926, 1606,
-1
1579, 1493, 1477,1439, 1320, 1292, 1165, 1122, 1073, 833, 734, 688 cm ; HRMS (ESI-TOF)
-
m/z: [M-H] Calcd for C H F OSe 316.9698; Found 316.9697.
1
3
8 3
4
-hydroxy-3-(phenylselanyl)benzaldehyde (3ai). The reaction was performed following the
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and 4-
hydroxybenzaldehyde 2i (48.9 mg, 0.4 mmol). The crude material was purified by flash
chromatography on silica gel (eluted with EtOAc:hexanes = 1:6) to give the product 3ai (51.6
1
mg, 93% yield) as a colorless oil. R = 0.36 (EtOAc:hexanes = 1:2); H NMR (400 MHz,
f
Chloroform-d) δ 9.86 (s, 1H), 8.18 (d, J = 2.0 Hz, 1H), 7.90 (dd, J = 8.4, 2.0 Hz, 1H), 7.29 –
1
3
1
7
.23 (m, 5H), 7.18 (d, J = 8.4 Hz, 1H), 7.09 (s, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-
d) δ 190.0, 161.7, 140.3, 133.7, 130.6, 130.4, 129.7, 129.6, 127.5, 116.5, 115.8 ppm; IR (thin
film): 3361, 3071, 2918, 2849, 2727, 1685, 1663, 1617, 1478, 1420, 1377, 1285, 1215, 1177,
-1
+
8
26, 739, 690, 622.6 cm ; HRMS (ESI-TOF) m/z: [M+Na] Calcd for C H NaO Se 300.9738;
13 10 2
Found 300.9738.
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 28 of 52
Liu Page 28
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
methyl 4-hydroxy-3-(phenylselanyl)benzoate (3aj). The reaction was performed following the
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and methyl 4-
hydroxybenzoate 2j (60.9 mg, 0.4 mmol). The crude material was purified by flash
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
chromatography on silica gel (eluted with EtOAc:hexanes = 1:9) to give the product 3aj (52.2
1
mg, 85% yield) as a white solid. m.p. = 90 – 91 °C; R = 0.36 (EtOAc:hexanes = 1:3); H NMR
f
(
400 MHz, Chloroform-d) δ 8.37 (d, J = 2.0 Hz, 1H), 8.04 (dd, J = 8.8, 2.4 Hz, 1H), 7.32 – 7.15
1
3
1
(
m, 5H), 7.09 (d, J = 8.8 Hz, 1H), 6.92 (s, 1H), 3.88 (s, 3H) ppm; C{ H} NMR (100 MHz,
Chloroform-d) δ 166.1, 160.5, 139.8, 133.9, 130.1, 130.0, 129.6, 127.2, 123.4, 115.3, 115.0, 52.1
ppm; IR (thin film): 3376, 2950, 1717, 1690, 1595, 1577, 1477, 1437, 1406, 1279, 1193, 1115,
-
1
+
1021, 972, 768, 737, 689 cm ; HRMS (ESI-TOF) m/z: [M+Na] Calcd for C H NaO Se
1
4
12
3
1
13
1
3
30.9844; Found 330.9845. The H and C{ H} data for this compound match the literature
data.15
3-(phenylselanyl)-[1,1'-biphenyl]-4-ol (3ak). The reaction was performed following the
General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and [1,1'-biphenyl]-
-ol 2k (68.1 mg, 0.4 mmol). The crude material was purified by flash chromatography on silica
4
gel (eluted with EtOAc:hexanes = 1:15) to give the product 3ak (36.4 mg, 56% yield) as a white
1
solid. m.p. = 85 – 86 °C; R = 0.34 (EtOAc:hexanes = 1:10); H NMR (400 MHz, Chloroform-d)
f
δ 7.81 (d, J = 2.0 Hz, 1H), 7.52 (dd, J = 8.8, 2.4 Hz, 1H), 7.46 (dd, J = 7.6, 1.6 Hz, 2H), 7.33 (t, J
=
7.6 Hz, 2H), 7.24 (d, J = 7.6 Hz, 1H), 7.21 – 7.17 (m, 2H), 7.16 – 7.10 (m, 3H), 7.06 (d, J =
1
3
1
8.4 Hz, 1H), 6.37 (s, 1H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 156.2, 139.8, 136.3,
1
3
34.6, 131.0, 130.7, 129.7, 129.6, 128.8, 127.1, 126.9, 126.7, 115.4 ppm; IR (thin film): 3410,
058, 3029, 1604, 1577, 1472, 1438, 1283, 1268, 1189, 1021, 999, 981, 829, 762, 734, 689, 665
-1
+
cm ; HRMS (ESI-TOF) m/z: [M+Na] Calcd for C H NaOSe 349.0102; Found 349.0101.
1
8
14
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
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Page 29 of 52
The Journal of Organic Chemistry
Liu Page 29
-(phenylselanyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol (3al). The reaction
1
2
3
4
5
6
7
8
9
2
was performed following the General Procedure A with phenyl benzyl selenoxide 1a (52.6 mg,
0.2 mmol) and methyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol 2l (88.0 mg, 0.4
mmol). The crude material was purified by flash chromatography on silica gel (eluted with
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
EtOAc:hexanes = 1:15) to give the product 3al (52.5 mg, 70% yield) as a colorless oil. R = 0.31
f
1
(
EtOAc:hexanes = 1:10); H NMR (400 MHz, Chloroform-d) δ 8.13 (d, J = 1.6 Hz, 1H), 7.81
(dd, J = 8.0, 1.6 Hz, 1H), 7.23 – 7.13 (m, 5H), 7.07 (d, J = 8.0 Hz, 1H), 6.71 (s, 1H), 1.32 (s,
1
3
1
1
1
2H) ppm; C{ H} NMR (100 MHz, Chloroform-d) δ 159.3, 145.2, 139.2, 130.8, 129.5, 129.4,
26.7, 114.7, 114.6, 83.8, 24.9 ppm; IR (thin film): 3042, 2978, 1594, 1576, 1489, 1372, 1354,
-1
-
1311, 1272, 1143, 1091, 1021, 963, 850, 733, 670 cm ; HRMS (ESI-TOF) m/z: [M-H] Calcd
for C H BO Se 375.0676; Found 375.0673.
1
8
20
3
2
-(phenylselanyl)naphthalen-1-ol (3am). The reaction was performed following the General
Procedure A with phenyl benzyl selenoxide 1a (52.6 mg, 0.2 mmol) and naphthalen-1-ol 2m
(57.7 mg, 0.4 mmol). The crude material was purified by flash chromatography on silica gel
(eluted with EtOAc:hexanes = 1:20) to give the product 3am (37.1 mg, 62% yield) as a pale
1
yellow solid. m.p. = 67 – 68 °C; R = 0.67 (EtOAc:hexanes = 1:10); H NMR (400 MHz,
f
Chloroform-d) δ 8.29 (dd, J = 7.6, 2.0 Hz, 1H), 7.79 (dd, J = 7.2, 2.0 Hz, 1H), 7.61 (d, J = 8.8
Hz, 1H), 7.55 – 7.48 (m, 2H), 7.36 (d, J = 8.4 Hz, 1H), 7.25 – 7.10 (m, 5H), 7.07 (s, 1H) ppm;
1
3
1
C{ H} NMR (100 MHz, Chloroform-d) δ 153.8, 135.8, 133.4, 131.2, 129.5, 129.5, 127.7,
127.6, 126.8, 125.8, 123.6, 123.4, 120.8, 107.7 ppm; IR (thin film): 3394, 3053, 1584, 1570,
1
501, 1476, 1451, 1393, 1387, 1262, 1250, 1204, 1193, 1148, 1021, 878, 802, 733, 688, 658 cm-
1;
HRMS (ESI-TOF) m/z: [M-H] Calcd for C H OSe 298.9981; Found 298.9979. The H and
-
1
1
6
11
1
3
1
16
C{ H} data for this compound match the literature data.
Metal-free Synthesis of Diaryl Selenides of Aryl Benzyl Selenoxides with Phenols
ACS Paragon Plus Environment