Synthesis of 2,2-diarylvinyl phenyl selenides by dehydration of 2-hydroxyalkyl phenyl selenides

Article abstract of DOI:10.1002/hc.21438

A novel route to 2,2-diarylvinyl phenyl selenides is reported by dehydration of the corresponding 2,2-diaryl-2-hydroxyethyl phenyl selenides, prepared by oxyphenylselenenylations of the corresponding 1,1-diarylethylenes, upon treatment with p-toluenesulfonic acid.

Full text of DOI:10.1002/hc.21438

Received: 1 June 2018
DOI: 10.1002/hc.21438
Revised: 24 July 2018
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R E S E A R C H A R T I C L E
Synthesis of 2,2-diarylvinyl phenyl selenides by dehydration of
2-hydroxyalkyl phenyl selenides
Nicolai Stuhr-Hansen
Department of Chemistry, University of
Copenhagen, Frederiksberg C, Denmark
Abstract
A novel route to 2,2-diarylvinyl phenyl selenides is reported by dehydration of the
corresponding 2,2-diaryl-2-hydroxyethyl phenyl selenides, prepared by oxyphe-
nylselenenylations of the corresponding 1,1-diarylethylenes, upon treatment with
p-toluenesulfonic acid.
Correspondence
Nicolai Stuhr-Hansen, Department of
Chemistry, University of Copenhagen,
Frederiksberg C, Denmark.
Email: nsh@chem.ku.dk
2-hydroxyalkyl phenyl selenides prone to fragmentation into
phenyl vinyl selenides upon acid treatment. During subjec-
1
INTRODUCTION
|
For decades, the phenylseleno (PhSe) group has been intro-
duced into organic molecules[1] by substitution at saturated
carbon atoms as a functionalizable unit, and most remarkably,
oxidation into corresponding selenoxide succeeded by selenox-
ide cycloelimination into selenium-free olefin has developed
into a widely applied technique for generation of advanced
alkene molecules.[2-4] To a far less extent, functionalization of
the vinylic chalcogen[5] analogues, that is, non-saturated phenyl
vinyl selenides,[6] have been investigated despite their potential
applications in construction of versatile ethylene derivatives[7,8]
and vinyl synthons.[9] Vinyl selenides have been prepared utiliz-
ing mercury reagents in stoichiometric quantities,[10,11] by heavy
metal cross-coupling[12] such as carboselenation[13] involving
unavailable precursors or via complex pre-synthetic steps.[14,15]
In search for general access to vinyl selenide synthons from more
readily available precursors, it was envisioned that phenyl vinyl
selenides would form upon dehydration of 2-hydroalkyl phenyl
selenides. It has been reported that upon O-activation of these
substrates either as mesylates[16,17] or as iodophosphites[18] treat-
ment with triethylamine lead to elimination into selenium-free
alkene. Similarly, 2-hydroxyalkyl selenides have been utilized
as means for smooth generation of alkene units[19] in synthesis
of selenium-free special products; however, dehydrations into
vinyl selenides systems with intact PhSe-substitution seem un-
reported. Intriguingly, treatment of 2-hydroxyalkyl phenyl sele-
nides under strictly acidic conditions could be imagined causing
protonation of the OH-function leading to fragmentation into
the corresponding phenyl vinyl selenide by water elimination.
It was believed that varying the alkyl substitution pat-
tern might lead to identification of readily synthesizable
tion of a short candidate series to p-toluenesulfonic acid, it
became apparent that 2,2-diaryl-2-hydroxyethyl 1-phenyl
selenides fragmented into corresponding 2,2-diarylvinyl
phenyl selenides by water elimination calling for variation
of the 2-aryl substitution pattern. Surprisingly, such stud-
ies seem yet unreported, since furthermore, it was found
that during standard smooth precursor synthesis utilizing a
highly acidic oxyphenylselenenylation reagent donor substi-
tution at the aryl system resulted solely in direct isolation
of the 2,2-diarylvinyl phenyl selenide bypassing hydroxy
selenide stage. Favorable electronic factors facilitated al-
kyldiarylcarbocation formation succeeded by spontaneous
elimination into vinyl selenide, overall considered as one-
pot 2,2-diarylvinyl phenyl selenide synthesis from par-
ent 1-arylstyrene. The present paper describes a new route
to 2,2-diarylvinyl phenyl selenides by p-toluenesulfonic
acid mediated water elimination from the corresponding
2-hydroxyalkyl phenyl selenides (Scheme 1).
2
RESULTS AND DISCUSSION
|
2-Hydroxyalkyl phenyl selenides for the dehydra-
tion studies were prepared from alkene precursors by
SCHEME 1 Synthesis of 2,2-diarylvinyl phenyl selenides from
2,2-diaryl-2-hydroxyethyl phenyl selenides
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Heteroatom Chemistry. 2018;e21438.
https://doi.org/10.1002/hc.21438
wileyonlinelibrary.com/journal/hc
© 2018 Wiley Periodicals, Inc.
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oxyphenylselenenylation.[1] Numerous hydroxy phenylse-
lenenylation reagents have been introduced, all PhSe+ syn-
thetic equivalents with an appropriate counter anion such
as chloride,[20] attacking an alkene with phenylselenenium
ions[21] forming the hydroxy selenide upon solvolysis
of intermediary phenylseleniranium ions. The reagent
couples PhSeSePh/peroxy disulfate[22] and PhSeSePh/
IBDA[23] have been widely applied as general oxyphe-
nylselenenylating reagents including methoxy- and ace-
toxy phenylselenenylation, and the extensive collection of
phenylselenenylating reagents also encompass PhSe+ salts
with organic counter ions for instance N-(phenylseleno)
phthalimide/acid[24] or N-(phenylseleno)saccharin.[25]
Henriksen reported that benzeneseleninic acid/diphenyl
diselenide/p-toluenesulfonic acid effectively generated
reactive phenylselenenyl p-toluenesulfonate[26] applied
by our group as general electrophilic aromatic organylse-
lenylation[27] reagents combining diorganyl diselenides
and stable protonated organylseleninic acid hydrotosylate
salts[28,29] as precursors for synthesis of unsymmetrical
aromatic selenides.[30] Thus, it seemed logical to explore
phenylselenenyl tosylate for synthesis of the required
2-hydroxyalkyl phenyl selenides. As representative sub-
strates for oxyphenylselenenylation studies, 1-hexene,
isobutylene, and 1,1-arylethylenes were employed. The
alkene was mixed with equimolar amounts of diphe-
nyl diselenide 1 and dihydroxyphenylselenonium p-
toluenesulfonate 2 for generation of the PhSe+ ion, which
attacked the alkene forming the resulting phenylselenira-
nium ion intermediate subsequently attacked by a water
molecule forming the corresponding 2-hydroxyalkyl phe-
nyl selenides (Table 1).
In order to attempt dehydrations, the 2-hydroxyalkyl
phenyl selenides Entries 1 and 3 (Table 1) were sub-
jected to treatment with p-toluenesulfonic acid in tol-
uene at elevated temperatures. These alcohols were
found practically inert at low temperatures, but above
80°C fragmentation of both compounds into undefined
decomposition products was observed. However, the
1,1-diphenyl derivative Entry 4 reacted in a more well-
defined manner, and by heating in a sealed tube at 130°C
for one hour a spot-to-spot reaction had occurred from
which 2,2-diphenylvinyl phenyl selenide[35] 3 was iso-
lated in 87% yield (Scheme 2).
3 is the first example of a vinyl selenide prepared by
dehydration of a 2-hydroxyalkyl phenyl selenide calling
for exploration of the reaction varying the aromatic sub-
stitution pattern of 1,1-diarylethylenes. However, since
only few of these precursors were commercially available,
it was crucial to develop a general protocol. A series of
1,1-diarylethylenes was prepared from the corresponding
arylbromides initially lithiated using tert-butyllithium suc-
ceeded by quenching of the formed aryllithiums with ethyl
acetate. The resulting carbinols were then reacted with p-
toluenesulfonic acid undergoing clean dehydrations into
the tolyl, xylyl, 4-fluoro and naphthyl derivatives affording
the 1,1-diarylethylenes 4-7, respectively, in 76-93% over-
all yields (Scheme 3).
1,1-Di(4-bromophenyl)ethylene[36]and1,1-di(4-cyanophenyl)
ethylene[37] were prepared by Wittig alkene synthesis re-
acting commercially available 4,4′-dibromobenzophenone
and 4,4′-cyanobenzophenone, respectively, with the ylid
of methyltriphenylphosphonium iodide generated by po-
tassium tert-butoxide treatment. 1,1-Di(4-methoxyphenyl)
ethylene[38] and 1,1-bis(4-(ethylthio)phenyl)ethene[39] were
prepared from 1,1-di(4-bromophenyl)ethylene by CuBr-
catalyzed nucleophilic aromatic substitution upon heating at
130°C. 1,1-Bis(4-nitrophenyl)ethylene[40] was prepared di-
rectly from 1,1-diphenylethylene by nitration utilizing 65%
nitric acid in concentrated sulfuric acid.
The series of 1,1-diarylethylenes was subjected to the
general phenylselenenylation conditions commencing with
1,1-di(4-methoxyphenyl)ethylene (Entry 5, Table 1); how-
ever, methoxy substitution stabilized diaryl alkyl cation for-
mation thereby spontaneously dehydrating the hydroxyalkyl
phenyl selenide and exclusively the 2,2-diarylvinyl phenyl
selenide, 1,1-bis(4-methoxyphenyl)-2-(phenylseleno)ethyl
ene 8, was isolated (Table 2). A similar tendency was ob-
served upon phenylselenenylation of 1,1-di(4-methylphenyl)
ethylene 4 (Entry 6, Table 1), but due to weaker electron do-
nation of the methyl group the corresponding 2-hydroxyethyl
phenyl selenide was isolated (69%); however, contaminated
with the spontaneously formed 2,2-diarylvinyl phenyl sele-
nide, 1,1-bis(4-methylphenyl)-2-(phenylseleno)ethylene 9
(24%). Not surprisingly, when reacting the dixylylethylene
By carrying out phenylselenenylations of 1-hexene
in aqueous acetonitrile, only one of the two possible
2-hydroxyalkyl phenyl selenides was obtained, that is,
1-(phenylseleno)-2-hexanol[31] (Entry 1, Table 1), an
8:1 regioselectivity ratio between the two possible re-
gioisomers using PhSeCl.[20] When carrying out phe-
nylselenenylation in aqueous acetonitrile in the presence
of sulfuric acid a selenium-stabilized Ritter reaction[32]
occurred leading to isolation of the corresponding, 2-
acetamidohexyl-1-phenylselenide and 1-acetamidohex
yl-2-phenylselenide, in a 9:1-ratio (Entry 2, Table 1).
Hydroxy phenylselenenylation of isobutylene proceeded
regiospecifically in analogy to reaction with PhSeCl[20]
leading to isolation of only one phenylselenylated iso-
mer, 2-methyl-1-(phenylseleno)propan-2-ol[33] (Entry
3, Table 1). As expected phenylselenenylation of
1,1-diphenylethylene proceeded regiospecifically anal-
ogous to the results reported upon phenylselenenyl sul-
fate[22] and PhSeSePh/Zn/AlCl3
mediation and solely
[34]
1,1-diphenyl-2-(phenylseleno)-ethan-1-ol was isolated
(Entry 4, Table 1).

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TABLE 1 Phenylselenenylation of alkenes with phenylselenenyl tosylate
Entry
R
R′
X
Solvent system
Time
A:B Isomer ratio
Yield
1
Bu
H
OH
H2O/DCM/MeCN
(1:1:20)
1 h
100 : 0
77%
2
Bu
H
NHAc
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
H2SO4 (12M aq.)/MeCN
(1:19)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(1:20:1)
H2O/MeCN/DCM
(0.1:20:1)
H2O/MeCN/DCM
(1:20:1)
1 h
90 : 10
100 : 0
100 : 0
N/A
86%a,b
92%c
76%
3
Me
Me
1 h
4
Ph
Ph
16 h
16 h
16 h
16 h
16 h
16 h
16 h
16 h
16 h
16 h
5
p-MeOPh
p-MePh
2,5-Xylyl
p-FPh
p-MeOPh
p-MePh
2,5-Xylyl
p-FPh
N/Ad
69%e
N/Ad
87%
6
100 : 0
N/A
7
8
100 : 0
100 : 0
N/A
9
p-BrPh
p-EtSPh
p-NCPh
1-Naphthyl
p-O2NPh
p- BrPh
p- EtSPh
p-NCPh
1-Naphthyl
p-O2NPh
83%
10
11
12
13
N/Ad
91%
100 : 0
N/A
N/Af
N/Ag
N/A
aIndirectly via Ritter-intermediate.
bRegiopure 2-acetamidohexyl-1-phenylselenide isolated by chromatography in 71% yield.
cReaction performed in an isobutylene atmosphere.
dAcid labile 2-hydroxyethyl phenyl selenide spontaneously dehydrated into vinyl selenide (Table 2).
ePartial dehydration (24%) into 2,2-diarylvinyl phenyl selenide.
fHeating above 60°C, 1 h gave undefined decomposition products.
gNo phenylselenenylation observed even upon prolonged heating at 130°C.
5 (Entry 7, Table 1) the two methyl substituents exerted a
sufficiently cation stabilizing effect directly leading to iso-
lation of the 2,2-diarylvinyl phenyl selenide, 1,1-bis(2,5-di
SH methylphenyl)-2-(phenylseleno)ethylene 10 (Table 2).
During phenylselenenylation of 1,1-bis(4-fluorophenyl)eth-
ylene 5, no spontaneous vinyl selenide formation occurred
leading to clean isolation of the 2-hydroxyethyl phenyl sele-
nide, 1,1-bis(4-fluo SH rophenyl)-2-(phenylseleno)-ethan- SH
1-ol (Entry 8, Table 1). The corresponding bromo analogue
displayed similar behavior affording 1,1-bis(4-bromopheny
l)-2-(phenylseleno)-ethan- SH 1-ol (Entry 9, Table 1) with
no vinyl selenide contamination. p-(Ethylthio) substitution
SCHEME 2 Acid induced elimination into vinyl selenide
(Entry 10, Table 1) was found sufficiently cation stabilizing
to bypass the 2-hydroxyalkyl phenyl selenide and solely the
2,2-diarylvinyl phenyl selenide, 1,1-bis(4-(ethylthio)phenyl)-
2-(phenylseleno)ethylene 13 (Table 2), was isolated. p-Cyano
substitution facilitated typical oxyphenylselenenylation

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TABLE 2 2,2-Diarylvinyl phenyl selenidesa
Compd. no.
X
Y
Z
Yield (%)
3
8
9
10
11
12
13
14
H
H
H
Me
H
H
H
H
H
H
H
H
Me
H
H
H
H
84
MeO
Me
H
F
Br
88b
80
72b
86
77
EtS
CN
85b
88
aReaction conditions: p-TsOH, toluene, 130°C, 1 h, sealed tube.
bNo heating required; over-all yield directly from 1,1-diarylethylene due to acid lability of the corresponding 2-hydroxyethyl phenyl selenide (Table 1).
SCHEME 3 Synthesis of 1,1-diarylethylenes
cleanly affording 1,1-bis- SH (4-cyanophenyl)(4-cyanophe
nyl)-2-(phenylseleno)-ethan-1-ol (Entry 11, Table 1). The
dinaphthylethylene 7 remained inert under the standard
phenylselenenylation conditions; however, at temperatures
above 60°C decomposition into non-defined products was
observed (Entry 12, Table 1). Nitro substitution completely
deactivated the arene system for phenylselenenylation and
the corresponding p-nitrophenyl analogue remained unre-
acted even upon heating at 130°C (Entry 13, Table 1).
The isolated 2,2-diaryl-2-hydroxyethyl phenyl sel-
enides (Table 1) were subjected to treatment with
p-toluenesulfonic acid in toluene at 130°C. For all com-
pounds, clean reactions were observed manifested by spot-
to-spot conversions according to TLC. By evaporation onto
celite succeeded by standard silica chromatography, the
corresponding 2,2-diarylvinyl phenyl selenides were iso-
lated (Table 2).
literature and thus the compounds 8-14 represent the first ex-
amples of substituted 2,2-diarylvinyl phenyl selenides. The
scope of the method was demonstrated by variation of aryl
substitution pattern without effecting yields. The method
for synthesis of 2,2-diarylvinyl phenyl selenides relies on
successful preparation of the corresponding 2-hydroxyalkyl
phenyl selenide precursors. However, there seemed no lim-
itations for the clean dehydration process into vinyl selenides
encouraging further development of hydroxy phenylselene-
nylation processes aiming for heavy metal-free synthesis of
vinyl selenides.
3
CONCLUSION
|
A procedure for synthesis of 2,2-diarylvinyl phenyl sele-
nides was developed by acid-mediated dehydration of
the corresponding 2-hydroxyalkyl phenyl selenides pre-
pared via alkene phenylselenenylation utilizing our rea-
gent phenylselenonium p-toluenesulfonate/PhSeSePh,
which was found capable of performing oxyphenylsele-
nenylation of alkenes with at least the same performance
as other reported phenylselenonium reagents. Overall
Previously, this type of vinyl selenide derivatives have
only been prepared via reactions with organomercurials,[10,11]
palladium catalyzed Suzuki cross-couplings requiring pre-
fabricated bromovinyl selenides,[12] or from silver/cop-
per mediated multiproduct arylselenylation procedures.[35]
Exclusively the diphenyl analogue 3 has been reported in

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2-hydroxyalkyl phenylselenenylation succeeded by dehy-
dration can be considered as a substitution of an alkene
proton for a phenylseleno unit. Most importantly, high
acidity of the phenylselenenyl tosylate reagent stimulated
spontaneous formation of three 2,2-diarylvinyl phenyl
selenides with donor substituted aryl systems bypassing
the hydroxy selenide stage causing this reagent to first
generate vinyl selenides moieties directly from parent
alkenes. The described procedure is practically the first
metal-free vinyl selenide synthesis facilitating generation
of the first series of arylsubstituted 2,2-diarylvinyl phenyl
selenides.
added rapidly within 1 minute under vigourous stirring.
After complete addition, stirring at room temperature was
maintained for 1 hour and the resulting faintly yellow slurry
was poured into ice (200 g) containing brine (20 mL) and
extracted with dichloromethane:heptane (2:3, 4 × 30 mL).
The pooled organic phases were dried over sodium sulfate,
filtered and evaporated. Separation using automated flash
chromatography on a 50 g silica column eluting with ethyl
acetate:heptane (1:19) afforded 1,1-bis(4-bromophenyl)eth-
ylene (0.76 g, 75%) as white crystals. Mp: 84-85°C (Lit. Mp:
87-88.5°C[36]). 1H NMR (300 MHz, CDCl3): δ 5.38 (s, 2H),
7.10 (d, J = 8.7 Hz, 4H), 7.38 (d, J = 8.7 Hz, 4H). 13C NMR
(75 MHz, CDCl3): δ 115.18, 122.06, 129.81, 131.45, 139.86,
148.03.
4
EXPERIMENTAL
Chemistry
|
1,1-Bis(4-methoxyphenyl)ethylene
4.1
|
Sodium methoxide (25 weight% in methanol, 324 mg,
1.5 mmol) was added to a solution of copper(I) bromide
(6 mg, 0.04 mmol) in DMF (2 mL) placed in a microwave
tube. 1,1-Bis(4-bromophenyl)ethylene (136 mg, 0.4 mmol)
was added and after sealing the tube with a lid heating at
120°C was maintained for two hours. The red slurry was
poured into ice (100 g) containing brine (10 mL) and ex-
tracted with dichloromethane:heptane (1:2, 3 × 30 mL).
The pooled organic extracts were washed with water
(30 mL), dried over sodium sulfate, filtered and evaporated.
Separation using automated flash chromatography on a
10 g silica column eluting with ethyl acetate:heptane (1:24)
gave 1,1-bis(4-methoxyphenyl)ethylene (79 mg, 82%). Mp:
All reagents and solvents were obtained from commer-
cial suppliers and used without further purification. Flash
column chromatography was performed on silica gel 60F
with solvent of HPLC grade. NMR-spectra were recorded
on a Bruker Avance 300 MHz equipped with a BBO probe.
Chemical shifts (δ) are reported relative to tetramethylsi-
lane (Me4Si). The following abbreviations are used for the
proton spectra multiplicities: s, singlet; br s, broad singlet;
d, doublet; dd, double doublet, triplet; q, quartet; sep, septet
m, multiplet. Coupling constants (J) are reported in hertz
(Hz). GCMS was recorded on an Agilent 6890 Series GC
system with a 5973 Network Mass Selective Detector.
High-resolution mass spectrometry (HRMS) was per-
formed by Ms. Anette Andersen on a Bruker Solarix XR
ESI/MALDI-FT-ICR-MS instrument equipped with a 7-
tesla magnet, and spectra were processed using Bruker Data
Analysis version 4.1.
1
142-144°C (Lit. Mp: 143-144°C[38]). H NMR (300 MHz,
CDCl3): δ 3.75 (s, 6H), 5.22 (s, 2H), 6.79 (d, J = 8.8 Hz,
4H), 7.20 (d, J = 8.8 Hz, 4H). 13C NMR (75 MHz, CDCl3): δ
55.29, 111.65, 113.45, 129.41, 134.32, 148.98, 159.30.
1,1-Bis(4-(ethylthio)phenyl)ethene[39]
To a mixture of ethanethiol (0.11 mL, 1.5 mmol) and DMF
(2 mL) placed in a microwave vial was added sodium hy-
dride (60% in mineral oil, 60 mg, 1.5 mmol) and stirring
under nitrogen was maintained at room temperature for
10 minutes. After stirring at room temperature for 10 min-
utes under nitrogen copper(I) bromide (6 mg, 0.04 mmol)
and 1,1-bis(4-bromophenyl)ethylene (203 mg, 0.6 mmol)
were added and after sealing the tube with a lid heating
at 130°C was maintained for two hours. The light-brown
reaction mixture was poured into ice (200 g) containing
brine (20 mL) and extracted with ethyl acetate (3 × 30 mL).
The pooled organic extracts were washed with water
(30 mL), dried over sodium sulfate, filtered and evaporated.
Separationusingautomatedflashchromatographyonsilicaelut-
ing with ethyl acetate:heptane (1:49) gave 1,1-bis(4-(ethylthio)
phenyl)ethene (117 mg, 65%) as white crystals. Mp: 114-
4.2
Synthesis of 1,1-diarylethylenes
|
4.2.1
Bromo (by Wittig alkene synthesis),
|
methoxy- and ethylthio (CuBr-catalyzed
nucleophilic aromatic substitution) analogues
1,1-Bis(4-bromophenyl)ethylene
Methyltriphenylphosphonium iodide (2.4 mmol) was pre-
pared in situ by adding methyl iodide (0.16 mL, 2.6 mmol)
to a solution of triphenylphosphine (0.62 g, 2.4 mmol) in dry
THF (8 mL) in a sealed jar fitted with a septum. After stir-
ring under argon for one hour, a heavy white precipitate had
formed. All solvent was removed in a stream of nitrogen.
A solution of 4,4′-dibromobenzophenone (0.68 g, 2 mmol)
in THF (10 mL) was added, and the slurry was placed in a
freezer at −18°C for 20 minutes. The jar was taken out of
the freezer, directly placed on a magnetic stirrer and potas-
sium tert-butoxide (1M in THF, 2.2 mL, 2.2 mmol) was
1
116°C (Lit.[41] Mp: 118°C). H NMR (300 MHz, CDCl3):
δ 1.26 (t, J = 7.4 Hz, 6H), 2.89 (q, J = 7.4 Hz, 4H), 5.33 (s,

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2H), 7.19 (s, 8H). 13C NMR (75 MHz, CDCl3): δ 14.38, 27.45,
113.79, 128.38, 128.68, 136.41, 138.74, 148.85.
1,1-Bis(4-fluorophenyl)ethylene[44] 6
Separation on a silica column eluting with heptane afforded
1,1-bis(4-fluorophenyl)ethylene 6. Yield: 0.58 g (89%).
White crystals. Mp: 44-45°C. 1H NMR (300 MHz, CDCl3): δ
5.30 (s, 2H), 6.89-6.97 (m, 4H), 7.16-7.23 (m, 4H). 13C NMR
(75 MHz, CDCl3): δ 114.13, 115.1 (d, JC-F = 21.5 Hz), 129.8
(d, JC-F = 8.0 Hz), 137.38, 148.07, 162.5 (d, JC-F = 249 Hz).
4.2.2
1,1-Diarylethylene derivatives
|
by lithiation of bromoarenes succeeded by
quenching of the aryllithium reagents with
ethyl acetate and in a terminating step acid-
mediated elimination from the intermediary
diarylcarbinol forming the corresponding
1,1-diarylethylenes
1,1-Bis(1-naphthyl)ethylene[45] 7
Separation on a silica column eluting with heptane afforded
1,1-bis(1-naphthyl)ethylene 7. Yield: 0.66 g (78%). White
crystals. Mp: 104-107°C (Lit. Mp: 108°C[46]). 1H NMR
(300 MHz, CDCl3): δ 5.79 (s, 2H), 7.26-7.38 (m, 8H), 7.66-
7.71 (m, 2H), 7.75-7.78 (m, 2H), 8.16 (d, J = 8.4 Hz, 2H).
13C NMR (75 MHz, CDCl3): δ 121.81, 125.66, 126.02,
126.17, 127.36, 127.94, 128.06, 128.48, 131.33, 133.78,
140.92, 146.95.
General procedure
tert-Butyllithium (1.5M in heptane, 8 mL, 12 mmol) was
added in a dropwise fashion during 10 minutes to effi-
ciently stirred THF (30 mL) cooled in a dry ice/acetone
bath under nitrogen. A solution of the corresponding ar-
ylbromide (6 mmol) in THF (3 mL) was added in a drop-
wise fashion during 5 minutes and stirring under nitrogen
was maintained for 30 minutes at −78°C during which
the generated aryllithium typically formed as a white pre-
cipitate. Ethyl acetate (0.29 mL, 3 mmol) was then added
during 5 minutes via syringe. After additional stirring for
10 minutes, the cooling bath was removed and stirring
at room temperature was continued for 30 minutes. The
resulting reaction mixture was poured into ice (300 g)
containing brine (30 mL) and extracted with ethyl acetate
(3 × 30 mL). The pooled organic extracts were dried over
sodium sulfate, filtered and evaporated affording the cor-
responding diarylethanol. A solution of p-toluenesulfonic
acid monohydrate (1.9 g, 10 mmol) in absolute etha-
nol (20 mL) was added and stirring was maintained for
16 hours. The clear colorless solution was poured into
ice (200 g) containing brine (20 mL) and extracted with
ethyl acetate (3 × 30 mL). The pooled organic extracts
were dried over sodium sulfate, filtered and evaporated
affording the crude diarylethylene.
4.2.3
1,1-Bis(4-cyanophenyl) derivative by
|
Wittig alkene synthesis
1,1-Bis(4-cyanophenyl)ethylene[37]
Methyltriphenylphosphonium iodide (0.72 mmol) was pre-
pared in situ by adding methyl iodide (0.049 mL, 0.078 mmol)
to a solution of triphenylphosphine (0.19 g, 0.72 mmol) in dry
THF (6 mL) in a sealed jar fitted with a septum. After stir-
ring under argon for one hour, a heavy white precipitate had
formed. All solvent was removed in stream of nitrogen. A
solution of 4,4′-dicyanobenzophenone (0.14 g, 0.6 mmol) in
THF (5 mL) was added, and the slurry was placed in a freezer
at −18°C for 20 minutes. The jar was taken out of the freezer,
directly placed on a magnetic stirrer and potassium tert-
butoxide (1M in THF, 0.66 mL, 0.66 mmol) was added rap-
idly within 1 minute under vigorous stirring. After complete
addition, stirring at room temperature was maintained for one
hour and the resulting faintly yellow slurry was poured into ice
(200 g) containing brine (20 mL) and extracted with ethyl ac-
etate (3 × 30 mL). The pooled organic phases were dried over
sodium sulfate, filtered and evaporated. Separation on a silica
column eluting with heptane afforded 1,1-bis(4-cyanophenyl)
ethylene (0.10 g, 72%) as a white crystalline mass. Mp: 155-
157°C (Lit. Mp: 158-158.5°C[47]). 1H NMR (300 MHz,
CDCl3): δ 5.38 (s, 2H), 7.10 (d, J = 8.5 Hz, 4H), 7.39 (d,
J = 8.5 Hz, 4H). 13C NMR (75 MHz, CDCl3): δ 115.19,
122.06, 129.81, 131.45, 139.86, 148.03.
1,1-Bis(4-methylphenyl)ethylene 4
Separation on a silica column eluting with heptane af-
forded 1,1-bis(4-methylphenyl)ethylene 4. Yield: 0.58 g
(93%). White crystals. Mp: 60-61°C (Lit. Mp: 60-61°C[42]).
1H NMR (300 MHz, CDCl3): δ 2.28 (s, 6H), 5.29 (s, 2H),
7.05 (d, J = 8.1 Hz, 4H), 7.15 (d, J = 8.1 Hz, 4H). 13C NMR
(75 MHz, CDCl3): δ 21.17, 112.97, 128.20, 128.84, 137.42,
138.85, 149.81.
1,1-Bis(2,5-dimethylphenyl)ethylene[43] 5
Separation on a silica column eluting with heptane afforded
1,1-bis(2,5-dimethylphenyl)ethylene 5. Yield: 0.54 g (76%).
4.2.4
Nitration of 1,1-diphenylethylene
|
1,1-Bis(4-nitrophenyl)ethylene[40]
1
Colorless oil. H NMR (300 MHz, CDCl3): δ 2.02 (s, 6H),
2.21 (s, 6H), 5.32 (s, 2H), 6.89-6.97 (6H, m). 13C NMR
(75 MHz, CDCl3): δ 20.20, 20.91, 118.88, 127.90, 130.26,
130.42, 132.42, 134.95, 141.98, 150.01.
1,1-Diphenylethylene (1.08 g, 6 mmol) was added in a drop-
wise fashion to sulfuric acid (conc., 18 mL) effectively cooled
in an ice/ethanol bath during 5 minutes. After complete

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7 of 10
|
addition, a mixture of nitric acid (65%, 0.46 mL, 6.6 mmol)
and sulfuric acid (conc., 3 mL) was added in a dropwise
fashion during 10 minutes under vigorous stirring. After
complete addition, stirring was maintained for a 15 minute
period keeping the temperature of the ice bath below -10°C.
The dark-orange reaction mixture was effectively quenched
by slowly pouring it into ice (150 g)/water (150 mL) under
extremely vigorous manual stirring and extracted with ethyl
acetate (3 × 50 mL). The pooled organic phases were washed
with brine (30 mL), dried over sodium sulfate, filtered, and
evaporated. Separation utilizing automated chromatography
on a silica column (100 g) using ethyl acetate-heptane (1:4)
afforded 1,1-bis(4-nitrophenyl)ethylene (0.61 g, 38%) as yel-
went from yellow to colorless. After pouring into sodium hy-
drogencarbonate (10% aq., 25 mL), the reaction mixture was
extracted with ethyl acetate (3 × 10 mL). The pooled extracts
were dried over sodium sulfate, filtered and evaporated afford-
ing a phenylselenide isomer mixture of the two regioisomers 2-
acetamidohexyl-1-phenylselenide:1-acetamidohexyl-2-phenyl
selenide (87:13; 149 mg, 86%) as a colorless crystalline mass.
The regioisomer ratio was determined by NMR.
4.3.3
2-Acetamidohexyl-1-phenylselenide
|
Separation of the crude product on silica (10 g) using ethyl
acetate-heptane (1:1) afforded regiopure 2-acetamidohexyl-
1-phenylselenide (123 mg, 71%) as colorless crystals. Mp:
69-71°C. Anal. Calcd for C14H21NOSe: C, 56.37; H, 7.10; N,
4.70. Found: C, 56.29; H, 6.99; N, 4.84. 1H-NMR (300 MHz,
CDCI3): δ 0.83-0.89 (3H, m), 1.22-1.31 (4H, m), 1.46-1.50
(1H, m), 1.56-1.60 (1H, m), 1.81 (1H, s), 3.05-3.16 (2H, m),
4.12-4.18 (1H, m), 5.73 (1H, m), 7.21-7.28 (3H, m), 7.51-
7.53 (2H, m). 13C-NMR (75 MHz, CDCI3): δ 13.93, 22.45,
23.23, 28.11, 33.65, 33.98, 49.16, 127.03, 129.21, 130.99,
132.48, 169.62.
1
low crystals. Mp: 169-173°C (Lit. mp: 175-176.5°C[48]). H
NMR (300 MHz, CDCl3): δ 7.35-7.42 (m, 4H), 7.48 (s, 2H),
8.17-8.27 (m, 4H). 13C NMR (75 MHz, CDCl3): δ 124.17,
129.58, 137.25, 140.83, 141.50, 145.35, 148.51, 149.31.
4.3
Phenylselenenylation of alkenes with
|
phenylselenenium tosylate
4.3.1
1-(Phenylseleno)-2-hexanol (Entry 1,
|
Table 1)[20,31,49,50]
4.3.4
2-Methyl-1-(phenylseleno)
|
Diphenyl diselenide 1 (59 g, 0.19 mmol) and dihydroxy phe-
nylselenonium p-toluenesulfonate[28] 2 (72 mg, 0.2 mmol)
were suspended in acetonitrile-water-dichloromethane
(20:1:1, 2 mL) and 1-hexene (0.15 mL, 0.67 mmol) was
added. Stirring was maintained at room temperature for one
hour. The faintly yellow solution was poured into sodium
hydrogencarbonate (10% aq., 30 mL), extracted with ethyl
acetate-heptane (1:4, 3 × 10 mL) and evaporated. Separation
on silica (10 g) using ethyl acetate-heptane (1:9) gave regio-
pure 1-(phenylseleno)-2-hexanol (115 mg, 77%) as a color-
less oil without detectable amounts of the other regioisomer
propan-2-ol[20,33] (Entry 3, Table 1)
A slurry of diphenyl diselenide 1 (59 mg, 0.19 mmol) and
dihydroxy phenylselenonium p-toluenesulfonate 2 (73 mg,
0.2 mmol) in acetonitrile-water-dichloromethane (20:1:1,
20 mL) was placed in a flask sealed with a rubber septum. An
isobutylene gas baloon was attached via a needle. Bubbling
through the reaction mixture was continued for one hour
maintaining a bubbling-pace of approximately 4-5 bubbles
per second. The resulting light-yellow solution was poured
into sodium hydrogencarbonate (10% aq., 10 mL), extracted
with heptane (3 × 30 mL) and evaporated. The pooled ex-
tracts were dried over sodium sulfate, filtered and evapo-
rated. Separation on silica (10 g) using ethyl acetate-heptane
(1:4) gave the regiopure alcohol (122 mg, 92%) as a colorless
oil. GC-MS (EI (m/z, relative intensity) 230 (M+, 41), 212
(9), 197 (7), 172 (100). 1H-NMR (300 MHz, CDCI3): δ 1.23
(6H, s), 2.14 (1H, br-s), 3.07 (2H, s), 7.05-7.27 (3H, m), 7.38-
7.56 (2H, m). 13C-NMR (75 MHz, CDCI3): δ 29.04, 44.82,
70.38, 125.98, 129.16, 130.93, 132.53.
1
was obtained, that is, 2-(phenylseleno)-1-hexanol. H-NMR
(300 MHz, CDCI3): δ 0.81-0.92 (3H, m), 1.16-1.59 (6H, m),
2.73 (1H, br-s), 2.81-2.90 (1H, m), 3.02-3.13 (1H, m), 3.58-
3.69 (1H, m), 7.13-7.27 (3H, m), 7.42-7.59 (2H, m). 13C-
NMR (75 MHz, CDCI3): δ 14.03, 22.68, 27.98, 36.34, 37.21,
69.92, 127.22, 129.53, 130.21, 132.90.
4.3.2
Table 1):[51,52]
2-Acetamidohexyl-1-phenylselenide
|
& 1-acetamidohexyl-2-phenylselenide (Entry 2,
4.3.5
2-Hydroxyethyl
|
Diphenyl diselenide 1 (59 mg, 0.19 mmol) and dihydroxy phe-
nylselenonium p-toluenesulfonate 2 (73 mg, 0.2 mmol) were
suspended in acetonitrile-water (20:1, 10 mL). Sulfuric acid
(18 M, 0.6 mL) was added during 10 minutes. After stirring for
10 minutes at room temperature, 1-hexene (0.38 mL, 2 mmol)
was added and stirring was maintained at room temperature for
one hour. Shortly after alkene addition, the reaction mixture
phenylselenenylation of 1,1-diphenylethylenes;
general procedure
To a slurry of diphenyl diselenide 1 (31 mg, 0.1 mmol) and
dihydroxy phenylselenonium p-toluenesulfonate 2 (36 mg,
0.1 mmol) in acetonitrile-water-dichloromethane (20:1:1,
2 mL) was added the corresponding 1,1-diarylethylene

8 of 10
STUHR-HANSEN
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(0.3 mmol) and stirring was maintained at room temperature
for 16 hours at room temperature. The resulting colorless/
light-yellow solution was poured into sodium hydrogen-
carbonate (10% aq., 100 mL), extracted with ethyl acetate
(3 × 25 mL) and evaporated. The pooled extracts were dried
over sodium sulfate, filtered, and evaporated.
(75 MHz, CDCI3): δ 21.06, 44.86, 77.29, 126.00, 127.20,
129.19, 129.30, 131.01, 136.95, 142.80.
1,1-Bis(2,5-dimethylphenyl)-2-(phenylseleno)ethylene
10 (Entry 7, Table 1; Table 2) isolated directly
Separation on silica using 2% ethyl acetate in heptane
afforded 1,1-bis(2,5-dimethylphenyl)-2-(phenylseleno)eth-
ylene 10 (84 mg, 72%) as a colorless oil. HRMS (ES+) calcd
for C24H25Se [M + H+]+, 393.1121; found, m/z 393.1114.
GC-MS (EI (m/z, relative intensity) 392 (M+, 100), 377
(31), 312 (9), 298 (14). 1H-NMR (300 MHz, CDCI3): δ 2.09
(3H, s), 2.16 (3H, s), 2.20 (3H, s), 2.25 (3H, s), 6.73 (1H,
s), 6.83-6.88 (m, 3H), 6.94-7.03 (m, 3H), 7.14-7.22 (m, 3H),
7.43-7.47 (3H, m). 13C-NMR (75 MHz, CDCI3): δ 20.79,
20.95, 21.02, 21.25, 125.15, 127.11, 127.45, 128.19, 129.23,
129.99, 130.59, 131.67, 131.89, 132.52, 133.29, 133.56,
134.66, 135.06, 140.36, 141.25, 142.36, 143.04.
4.3.6
1,1-Diphenyl-2-(phenylseleno)-ethan-
|
1-ol[34] (Entry 4, Table 1)
Performed in 10 times larger scale than the general procedure
(3 mmol scale). Separation on silica using 5% ethyl acetate
in heptane afforded 1,1-diphenyl-2-(phenylseleno)-ethan-1-
ol (0.81 g, 76%) as colorless crystals. Mp: 90-91°C. 1H-NMR
(300 MHz, CDCI3): δ 3.54 (1H, s), 3.86 (2H, s), 7.18-7.32 (8H,
m), 7.40-7.53 (7H, m). 13C-NMR (75 MHz, CDCI3): δ 44.73,
77.48, 126.09, 127.34, 128.09, 128.93, 130.13, 133.15, 145.47.
1,1-Bis(4-fluorophenyl)-2-(phenylseleno)-ethan-1-ol
(Entry 8, Table 1)
4.3.7
1,1-Bis(4-methoxyphenyl)-2-
|
(phenylseleno)ethylene 8 (Entry 5, Table 1;
Table 2) isolated directly bypassing the
2-hydroxyalkyl phenyl selenide
Separation on silica using 5% ethyl acetate in heptane af-
forded the 1,1-diaryl-2-(phenylseleno)-ethan-1-ol (102 mg,
87%) as a colorless oil. HRMS (ES+) calcd for C20H15F2Se
[M + H+ - H2O]+, 373.0307; found, m/z 373.0256. 1H-NMR
(300 MHz, CDCI3): δ 3.51 (1H, s), 3.71 (2H, s), 6.87 (t,
J = 8.8 Hz, 4H), 7.09-7.16 (m, 3H), 7.24-7.31 (m, 4H), 7.37-
7.41 (2H, m). 13C-NMR (75 MHz, CDCl3): δ 44.78, 77.51,
115.16 (d, JC-F = 21 Hz), 127.56, 127.86 (d, JC-F = 8 Hz),
129.31, 130.29, 133.33, 141.09 (d, JC-F = 3 Hz), 161.98 (d,
JC-F = 246 Hz).
Separation on silica using 4% ethyl acetate in heptane di-
rectly afforded the 2,2-diarylvinyl phenyl selenide 8 (104 mg,
88%) as a colorless oil. HRMS (ES+) calcd for C22H21O2Se
[M + H+]+, 397.0707; found, m/z 397.0652. 1H-NMR
(300 MHz, CDCl3): δ 3.70 (3H, s), 3.76 (3H, s), 6.72 (d,
J = 9.2 Hz, 2H), 6.84-6.88 (m, 3H), 7.08-7.72 (m, 7H), 7.47-
7.50 (2H, m). 13C-NMR (75 MHz, CDCI3): δ 55.26, 55.31,
113.65, 113.80, 119.31, 127.20, 128.49, 129.25, 130.63,
131.55, 131.99, 132.19, 132.27, 132.92, 134.80, 142.83,
159.02, 159.21.
1,1-Bis(4-bromophenyl)-2-(phenylseleno)-ethan-1-ol
(Entry 9, Table 1)
Separation on silica using 5% ethyl acetate in heptane afforded
the 1,1-diaryl-2-(phenylseleno)-ethan-1-ol (97 mg, 83%)
as a colorless oil. HRMS (ES+) calcd for C20H16Br2NaOSe
[M + Na+]+, 534.8610; found, m/z 534.8598. 1H-NMR
(300 MHz, CDCI3): δ 3.50 (1H, br-s), 3.68 (2H, s), 7.10-7.19
(m, 7H), 7.29-7.39 (m, 6H). 13C-NMR (75 MHz, CDCI3):
δ 44.11, 76.87, 121.69, 127.62, 127.80, 129.33, 130.00,
131.48, 133.40, 144.00.
4.3.8
Phenylselenenylation of 1,1-bis
|
(4-methylphenyl)ethylene gave hydroxy-
phenylselenenylation “contaminated” with the
corresponding 2,2-diarylvinyl phenyl selenide
(Entry 6, Table 1)
1,1-Bis(4-methylphenyl)-2-(phenylseleno)ethylene 9
Separation on silica initially utilizing 1% ethyl acetate in hep-
tane gave a fraction containing 1,1-bis(4-methylphenyl)-2-
(phenylseleno)ethylene (26 mg, 24%).
1,1-Bis(4-(ethylthio)phenyl)-2-(phenylseleno)ethylene
13 (Entry 10, Table 1; Table 2) isolated directly
Separation on silica using 2% ethyl acetate in heptane directly
gave the 2,2-diarylvinyl phenyl selenide 13 (116 mg, 85%) as
a colorless oil. GC-MS: EI (m/z, relative intensity) 456 (M+,
91), 395 (61), 376 (78), 314 (30), 292 (57), 214 (100). HRMS
(ES+) calcd for C24H25S2Se [M + H+]+, 457.0563; found, m/z
457.0555. 1H-NMR (300 MHz, CDCI3): δ 1.18-1.32 (6H, s),
2.85 (q, J = 7.2 Hz, 2H), 2.92 (q, J = 7.2 Hz, 2H), s: 6.99 (s,
1H), 7.04-7.19 (m, 6H), 7.22-7.28 (m, 5H), 7.47-7.51 (2H, m).
1,1-Bis(4-methylphenyl)-2-(phenylseleno)-ethan-1-ol
Continuous elution using 5% ethyl acetate in heptane af-
forded the title 1,1-bis(4-methylphenyl)-2-(phenylseleno)-
SH ethan ethan-1-ol (79 mg, 69%) as a colorless oil. HRMS
(ES+) calcd for C22H21Se [M + H+ - H2O]+, 365.0808;
1
found, m/z 365.0801. H-NMR (300 MHz, CDCI3): δ 2.21
(6H, s), 3.75 (2H, s), 7.00 (4H, d, J = 8.1 Hz), 7.10-7.13 (3H,
m), 7.22 (4H, d, J = 8.1 Hz), 7.39-7.42 (2H, m). 13C-NMR

STUHR-HANSEN
9 of 10
|
13C-NMR (75 MHz, CDCI3): δ 14.12, 14.35, 27.27, 27.52,
122.32, 127.57, 128.04, 128.61, 129.33, 129.80, 131.45,
131.53, 132.54, 135.90, 136.87, 137.37, 139.07, 141.91.
CDCl3): δ 122.59, 127.20, 127.45, 127.96, 128.14, 128.33,
128.78, 129.35, 129.65, 131.66, 132.56, 140.41, 141.64,
143.15.
1,1-Bis(4-cyanophenyl)-2-(phenylseleno)-ethan-1-ol
(Entry 11, Table 1)
4.4.3
1,1-Bis(4-methylphenyl)-2-
|
(phenylseleno)ethylene 9
Separation on silica using 5% ethyl acetate in heptane afforded
the 1,1-diaryl-2-(phenylseleno)-ethan-1-ol (110 mg, 91%) as
yellowish crystals. Mp: 112-113°C. 1H-NMR (300 MHz,
CDCI3): δ 3.50 (1H, s), 3.68 (2H, s), 7.09-7.20 (m, 7H), 7.32
(d, J = 8.6 Hz, 4H), 7.36-7.39 (2H, m). 13C-NMR (75 MHz,
CDCI3): δ 44.11, 77.25, 121.69, 127.62, 127.80, 128.12,
129.32, 129.82, 131.48, 133.40, 144.00.
Yield: 29 mg, 80%. White crystals. Mp: 77-78°C. HRMS
(ES+) calcd for C22H21Se [M + H]+, 365.0808; found, m/z
365.0801. GC-MS: EI (m/z, relative intensity) 364 (M+,
67), 349 (53), 284 (34), 268 (51), 253 (7), 206 (21), 191
(100). 1H NMR (300 MHz, CDCl3): δ 2.24 (s, 3H), 2.32 (s,
3H), 6.95-7.07 (m, 8H), 7.16 (s, 1H), 7.18-7.24 (m, 3H),
7.47-7.50 (m, 2H). 13C NMR (75 MHz, CDCl3): δ 21.11,
21.37, 120.82, 127.14, 127.25, 128.96, 129.17, 129.23,
129.25, 131.89, 132.37, 137.04, 137.57, 137.63, 139.06,
143.29.
Attempted synthesis of 1,1-bis(1-naphthyl)-2-
(phenylseleno)-ethan-1-ol (Entry 12, Table 1)
After stirring for sixteen hours at room temperature TLC-
examination showed no alkene selenenylation. Upon heating
above 60°C several undefined products formed.
4.4.4
1,1-Bis(4-fluorophenyl)-2-
|
(phenylseleno)ethylene 11
Attempted synthesis of 1,1-bis(4-nitrophenyl)-2-
(phenylseleno)-ethan-1-ol (Entry 13, Table 1)
After stirring for sixteen hours at room temperature, TLC-
examination showed no alkene selenenylation. Upon heat-
ing at 60°C for one hour decomposition into a non-defined
complex non-hydroxyselenide containing product mixture
was observed.
Yield: 32 mg, 86%. Colorless oil. GC-MS: EI (m/z, relative
intensity) 372 (M+, 52), 292 (47), 271 (19), 214 (100). HRMS
(ES+) calcd for C20H15F2Se [M + H+]+, 373.0307; found,
1
m/z 373.0300. H NMR (300 MHz, CDCl3): δ 6.86-6.92
(s, 2H), 6.96 (s, 1H), 7.01-7.13 (m, 4H), 7.18-7.27 (m, 5H),
7.46-7.51 (m, 2H). 13C NMR (75 MHz, CDCl3): δ 115.25 (d,
JC-F = 21.6 Hz), 115.61 (d, JC-F = 21.6 Hz), 122.69, 127.61,
128.71 (d, JC-F = 8.0 Hz), 129.39, 131.09 (d, JC-F = 8.3 Hz),
131.21, 132.63, 136.09 (d, JC-F = 3.5 Hz), 137.72 (d, JC-
F = 3.3 Hz), 141.02, 160.66 (d, JC-F = 10.8 Hz), 163.93 (d,
JC-F = 11.3 Hz).
4.4
Synthesis of 2,2-diarylvinyl
|
phenyl selenides
4.4.1 General procedure
|
4.4.5
1,1-Bis(4-bromophenyl)-2-
|
An effectively stirred slurry of the corresponding 1,1-diaryl-2-
(phenylseleno)-ethan-1-ol (0.1 mmol) and p-toluenesulfonic
acid monohydrate (6 mg, 0.03 mmol) in toluene (1 mL) was
heated in a sealed microwave tube in an oil bath at 130°C
for one hour. The resulting light-yellow slightly colloid sus-
pension was evaporated onto celite in a stream of air. Direct
separation on silica eluting with 2% ethyl acetate in heptane,
evaporation of solvent and drying in a vacuum oven (45°C,
0.6 mbar, 2 hours) afforded the corresponding 2,2-diarylvinyl
phenyl selenide.
(phenylseleno)ethylene 12
Yield: 38 mg, 77%. White crystals. Mp: 102-103°C. HRMS
(ES+) calcd for C20H15Br2Se [M + H]+, 494.8685; found, m/z
494.8674. GC-MS: EI (m/z, relative intensity) 494 (M+, 16),
412 (15), 334 (24), 256 (44), 176 (100). 1H NMR (300 MHz,
CDCl3): δ 6.98 (2H, d, J = 8.5 Hz), 7.04 (s, 1H), 7.10-7.17
(s, 2H), 7.23-7.32 (m, 5H), 7.46-7.50 (m, 4H). 13C NMR
(75 MHz, CDCl3): δ 121.48, 122.21, 127.79, 128.62, 129.18,
130.95, 131.00, 131.51, 131.55, 131.92, 132.70, 138.69,
140.08, 140.50.
4.4.2
1,1-Diphenyl-2-(phenylseleno)
|
ethylene[6,12]
3
4.4.6
1,1-Bis(4-cyanophenyl)-2-
|
(phenylseleno)ethylene 14
Performed in 20 times larger scale than the general proce-
dure (2 mmol scale). Yield: 0.56 g, 84%. Colorless oil. GC-
MS: EI (m/z, relative intensity) 336 (M+, 61), 255 (39), 278
Yield: 34 mg, 88%. White crystals. Mp: 90-91°C. Anal.
Calcd for C22H14N2Se: C, 68.58; H, 3.66; N, 7.27. Found:
1
1
(100). H NMR (300 MHz, CDCl3): δ 7.03 (s, 1H), 7.12-
C, 68.51; H, 3.92; N, 6.99. H NMR (300 MHz, CDCl3): δ
7.36 (m, 13H), 7.47-7.59 (m, 2H). 13C NMR (75 MHz,
6.99 (2H, d, J = 8.1 Hz), 7.05 (1H, s), 7.10-7.18 (3H, m),

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STUHR-HANSEN
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[23] M. Tingoli, M. Tiecco, L. Testaferri, A. Temperini, Synth.
Commun. 1998, 28, 1769.
7.23-7.26 (2H, m), 7.31 (2H, d, J = 8.3 Hz), 7.46-7.54 (m,
4H). 13C NMR (75 MHz, CDCl3): δ 121.48, 122.21, 124.33,
127.73, 127.79, 128.63, 129.18, 129.45, 130.96, 131.55,
131.74, 131.92, 132.78, 138.69, 140.08, 140.50.
[24] P. A. Grieco, J. Y. Jaw, D. Claremon, K. Nicolaou, J. Org. Chem.
1981, 46, 1215.
[25] M. Tingoli, R. Diana, B. Panunzi, Tetrahedron Lett. 2006, 47,
7529.
[26] L. Henriksen, Tetrahedron Lett. 1994, 35, 7057.
[27] W. Jin, P. Zheng, W. T. Wong, G. L. Law, Asian J. Org. Chem.
2015, 4, 875.
ACKNOWLEDGMENTS
Prof. Lars Henriksen is thanked for fruitful discussions.
Ms. Annette Andersen is thanked for carrying out HRMS
experiments.
[28] L. Henriksen, N. Stuhr-Hansen, Synth. Commun. 1996, 26, 1897.
[29] N. Stuhr-Hansen, B. Ebert, P. Krogsgaard-Larsen, J. Kehler, Org.
Lett. 2000, 2, 7.
[30] N. Stuhr-Hansen, T. I. Sølling, L. Henriksen, Tetrahedron 2011,
67, 2633.
ORCID
[31] S. Berlin, C. Ericsson, L. Engman, J. Org. Chem. 2003, 68, 8386.
[32] I. Fechete, V. Jouikov, C. R. Chim. 2014, 17, 634.
[33] W. Zhang, H. Yu, Y. Gao, J. Meng, T. Matsuura, Chem. Commun.
2003, 47, 498.
Nicolai Stuhr-Hansen
org/0000-0001-7497-8915
http://orcid.
[34] B. Movassagh, S. Farshbaf, Synthesis 2010, 33.
[35] H. Sahoo, A. Mandal, J. Selvakumar, M. Baidya, Eur. J. Org.
Chem. 2016, 4321.
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How to cite this article: Stuhr-Hansen N. Synthesis
of 2,2-diarylvinyl phenyl selenides by dehydration of
2-hydroxyalkyl phenyl selenides. Heteroatom Chem.
2018;e21438. https://doi.org/10.1002/hc.21438
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