- Email: [email protected]
Reaction of alkynyltrimethylsilanes with a hypervalent organoiodine compound: A new general synthesis of alkynyliodonium salts
Tetrahedron Letters,Vo1.26,No.37,Dp 4501-4504,1985 Printed in Great Britain
0040-4039/85 $3.00 + .OO 01985 Perqamon Press Ltd.
REACTION OF ALKYNYLTRIMETHYLSILANESWITH A HYPERVALENT ORGANOIODINE COMPOUND: A NEW GENERAL SYNTHESIS OF ALKYNYLIODONIUM SALTS
MasahitoOchiai, Munetaka Kunishima, Kenzo Sumi, Yoshimitsu Nagao, and Eiichi Fujita* Institute
for Chemical
Research,
Kyoto University,
Masao Arimoto Osaka College
Summary:
New general methods
from alkynyltrimethylsilanes tetrafluoroborate the reaction
or boron trifluoride
to numerous
about alkynyliodonium
ranging
and Hideo Yamaguchi Matsubara,
for the synthesis 1 utilizing
studies
salts.ly2
from lithium
etherate
580, Japan
of alkynyl(phenyl)iodonium
tetrafluoroborate
of iodosylbenzene
were developed.
from 12 - 20%.3
on the chemistry
2
and triethyloxonium
The medium
of diaryliodonium
effect observed
The reaction
by the reaction
with
tosylate
in
of alkynyliodonium
R -E-SiMe8
salts 2 utilizing
tosylate.
salt at all.4
Furthermore,
2
Method A
:
(C6H510),, Et30+BF4-, CH2C12
Method
:
(C6H510),, BF3-Et20, CH2C12, and then aq NaBF4 1
4501
in yields
but the reaction
We now report
alkynyltrimethylsilanes
1
Scheme
was
with phenylacetylene
in 60% yield,
-->
B
is known
[hydroxy(tosyloxy)iodo]benzene
only a 5% yield of phenyl(B-cyclohexylethynyl)iodonium alkynyliodonium
chloride
(dichloroiodo)benzene
of [hydroxy(tosyloxy)iodo]benzene
with cyclohexylacetylene,
heptyne did not give the corresponding synthesis
salts, little
In 1965, phenyl(B-phenylethynyl)iodonium
phenylacetylide
does not seem to be general:
general
Osaka-Fu
the combination
has been found to give phenyl(B-phenylethynyl)iodonium
afforded
611, Japan
was also discussed.
In contrast
synthesized
of Pharmacy,
Uji, Kyoto-Fu
l-
the first,
l_ (Scheme 1).
4502
Synthesis
Table 1.
of Alkynyliodonium
Salts from Alkynylsilanes
Reaction Entry
1
R
1
la __
n-C8H17
2
la __
n-C8H17
3
lb __
cycle-C6H11
4
lc -_
'gH5
5
lc _...
'gH5
6
Id _..,
'gHgCH2
7
Id -_
'gHgCH2
8
le _...
a)
polymeric
FABMSb
(%)
(m/z)
2a __
70
2a
85
25
2b _."
27
59.5-65
341
64
137-138
311
2c
65
oil
305
2c ..,..,
79
2d __
56
oil
319
3
2dC
53
18
2e _-_
75
oil
333
22 2.5
3 24
b)
Yielda
Peaks corresponding
c)
to (M-BF4)+.
Acetylenic
ketone 7 was also
in 11% yield.
Although 5 rather low.
dioxane,
Product
Time (hr)
C6H5CH2CH2
Isolated yields.
obtained
Method
iodosylbenzene
has been shown to be a useful oxidizing
The low reactivity
nature6
and the very low solubility
dimethylsulfoxide,
silane 1 and iodosylbenzene tetrafluoroborate of iodosylbenzene
of iodosylbenzene
in dichloromethane
or boron trifluoride in the synthesis
toward common organic
Thus no reaction was observed
etc.).
reagent,
may be attributable
solvents
between
at room temperature.
salts 2.
(dichloromethane,
alkynyltrimethyl-
for the activation
When I-trimethylsilyldec-I-yne
(la) was treated with iodosylbenzene (1.6 equiv.) and trieth;loxonium tetrafluoroborate _equiv.) in dichloromethane at room temperature (Method A), 1-decynyl(phenyl)iodonium tetrafluoroborate (1.6 equiv.)
(2a)7 was obtained
directly
in 70% yield.
in the""presence of boron trifluoride
room temperature
followed
by the treatment
etherate
Reaction
of la with
(1.6 equiv.)
(1.6
iodosylbenzene
in-dichloromethane
with excess amounts of aqueous
at
sodium tetrafluoro-
Similarly, alkynylsilanes (lb - e) gave (Method B), also gave rise to 2a in 85% yield. --. __ The results are summarized in Table iodonium salts (2b - e) in good yields. _-. _ Fast atom bombardment mass spectra (FABMS) of the alkynyliodonium tetrafluoroborates 2
borate
the corresponding 1.
is
Triethyloxonium
etherate was found to be essential
of alkynyliodonium
the reactivity
in part to the proposed
showed relatively
abundant fragments corresponding to the cationic portion of the salts. -1R -1 characteristic of the BF4spectra of 2 showed a very large broad band at 1100 - 1000 cm 8 In-the I3 C n.m.r. spectra of 2, a characteristic signal corresponding to the anion. acetylenic
carbon atom bearing
the iodine
(III)
substituent
appeared
at near 6 15:' for
4503
example,
$a_ :
6 15.6, 2! : 6 16.1, 2' : 6 17.9.
Interesting the iodonium
medium
In addition to the formation of in the reaction. 10 was obtained as a minor product in the ketone 7
effect was observed
salt 2d (53%), an acetylenic __ etherate-catalyzed reaction
boron trifluoride
(Entry 7)
dichloromethane". carried
out in dioxane:
trifluoride yield.
etherate
(Method B) of trimethylsilylalkyne
The reaction mode,
Id, on treatment
"in-dioxane"
however,
was much altered
with excess amounts
at room temperature
With 3-(p-methoxyphenyl)-1-trimethylsilylprop-1-yne,
8 was obtained.
The oxidation
to acetylenic
Transient
intermediates
with BF3-activated the formation
produced
of vinyl cations 4,
iodosylbenzene
3, may produce
of the hypervalent
sequence
by the reaction
the alkynyliodonium
16-I-3 species
the ketone 7 in 69%
5 by desilylation
ketone
at all in the reaction
the reaction
la in dioxane. __ Scheme 2 seems to be plausible.
of alkynylsilanes
tetrafluoroborates
(path a).
via
When the reaction
C6H51LOBF3
l
-
3
RCH2-w-;
5
“,>
0SiMe3
.->
16
'gH5
G. F. Koser, in 'The chemistry Rappoport,
BF4-
0
7 R=C6H5
References
2.
RCH2-_,=--I+-C6H5
. ..-.iM'.;
Scheme
1.
NaBF4
'gH5 .
'gH5
4 aq
dioxane (R=Ar)
to 6
z-SiMe3
BF3-Et20
1Path bN
of
shown in
of Id is carried out in dioxane, path b may becGe important and form allenyliodine(II1) __ Nucleophilic attack of oxygen of iodosylbenzene intermediate 6 (R=C6H5) by deprotonation. 11 may afford the ketone 7.
(C6H510)n
was
and boron
a 52% yield of acetylenic
ketones was not observed
In view of these observations,
alkynylsilane
if the reaction
of iodosylbenzene
for 15 hr, afforded
Id "in
of halides,
John Wiley and Sons, Chichester, tosylates
2
3
8 R=p-MeOC6H5
and Notes
pseudo-halides
and azides,'
ed. S. Patai and Z.
1983, Part 2, Ch. 25.
Synthesis
of alkynyl
from phenyl(alkynyl)iodonium
recently:
P. J. Stang and B. W. Surber, J. Am. chern.sm.,
tosylates
was reported
107, ___ 1452 (1985).
4504
3.
F. M. Beringer
4.
G. F. Koser, L. Rebrovic,
5.
(a) T. Takaya, Moriarty, Godoy,
Org.
&em.,
H. Enyo, and E.
Imoto,
J.
30, 1930 (1965). ."_ Org. Chem., 46, 4324
(e) W. Ando, R. Tajima,
(a) H. Siebert J.
Selected
6 O.BB(t, 3;: J 6.8Hz),
2H, J 7.3Hz), 6 14.3(q),
7.52-7.58(m,
15.6(s),
8.
N. N. Greenwood,
9.
The I3 C n.m.r.
J.
SW., 105, -*23, 1685 (1982).
(b)"R. Bell and K. J.
1.20-1.40(m,
720, and 660 cm -I; 'H n.m.r.
IOH), 1.59(quint, and 8.05-B.lO(m,
&em.
spectrum
t), 113.5,
1959, 3811. ____ of I-iodohex-1-yne showed the signal of a-acetylenic and G. E. Maciel,
J.
Phys.
during
the reaction
iodosylbenzene
in the presence
fact the alcohol
9 prepared
silylacethylene,
on treatment
may be considered.
of boron trifluoride
by the reaction
114.l(each
s),
etherate
9 is oxidized
to give the ketone 7.
for 6 hr, afforded
(C6H510)n 'gH5
(Received in Japan 28 May 1985)
l
NysiMe 9
In
with I-lithio-2-trimethyl-
OH A
with
(1.6 equiv.) and boron trifluoride
at rocm temperature
H2°
carbon atom at
of 6 (R=C6H5) with
Alcohol
of benzaldehyde
with iodosylbenzene
in dioxane
-
(CDC13):
69, 1348 (1965).
Chem.,
and B. Wahle, Chem. Ber., 116, 3309 (1983). __ ___ reaction course, nucleophilic substitution
6 (R=C6~5)
2.64(t,
13C n.m.r.
Sot.,
possible
(1.6 equiv.)
2H, J 7.3Hz),
2H).
(400
d).
water produced
etherate
2180, 1120-980,
20.8, 22.6, 27.5, 28.7, 28.8, 29.0, 31.7(each
6 -3.3: D. D. Traficante 10. L. Birkofer
and J.
Chem.
he-h?.,
426, 173 (1976); -__
them.,
2H), 7.64-7.70(m,lH),
132.6, 133.0, and 134.0(each
11. As another
AZZg.
1960, 1209. _..,..,_ data: 2a, i.r.(CHC13):
Tetmhedron
(b) R. M.
(c) R. Muller
Sot.,
spectral
MHZ; CDC13):
22, 1283 ?;981); -_ and T.E. Nemo, J. Am.
Lett.,
and T. Takata,
and M. Handrich, Anorg.
Chem.
(1981).
BUZZ. Chem. Sec. Jpn., "-41, 1032 (1968);
ibid.,..,_ 22, 2361 (1981); (d) J. T. Groves
Morgan, 7.
J.
and R. H. Wettach,
H. Hu, and S. C. Gupta, !?etrahe&on
5786 (1983); 6.
and S. A. Galton,
3
BF3-Et20
7 in 77% yield.
0040-4039/85 $3.00 + .OO 01985 Perqamon Press Ltd.
REACTION OF ALKYNYLTRIMETHYLSILANESWITH A HYPERVALENT ORGANOIODINE COMPOUND: A NEW GENERAL SYNTHESIS OF ALKYNYLIODONIUM SALTS
MasahitoOchiai, Munetaka Kunishima, Kenzo Sumi, Yoshimitsu Nagao, and Eiichi Fujita* Institute
for Chemical
Research,
Kyoto University,
Masao Arimoto Osaka College
Summary:
New general methods
from alkynyltrimethylsilanes tetrafluoroborate the reaction
or boron trifluoride
to numerous
about alkynyliodonium
ranging
and Hideo Yamaguchi Matsubara,
for the synthesis 1 utilizing
studies
salts.ly2
from lithium
etherate
580, Japan
of alkynyl(phenyl)iodonium
tetrafluoroborate
of iodosylbenzene
were developed.
from 12 - 20%.3
on the chemistry
2
and triethyloxonium
The medium
of diaryliodonium
effect observed
The reaction
by the reaction
with
tosylate
in
of alkynyliodonium
R -E-SiMe8
salts 2 utilizing
tosylate.
salt at all.4
Furthermore,
2
Method A
:
(C6H510),, Et30+BF4-, CH2C12
Method
:
(C6H510),, BF3-Et20, CH2C12, and then aq NaBF4 1
4501
in yields
but the reaction
We now report
alkynyltrimethylsilanes
1
Scheme
was
with phenylacetylene
in 60% yield,
-->
B
is known
[hydroxy(tosyloxy)iodo]benzene
only a 5% yield of phenyl(B-cyclohexylethynyl)iodonium alkynyliodonium
chloride
(dichloroiodo)benzene
of [hydroxy(tosyloxy)iodo]benzene
with cyclohexylacetylene,
heptyne did not give the corresponding synthesis
salts, little
In 1965, phenyl(B-phenylethynyl)iodonium
phenylacetylide
does not seem to be general:
general
Osaka-Fu
the combination
has been found to give phenyl(B-phenylethynyl)iodonium
afforded
611, Japan
was also discussed.
In contrast
synthesized
of Pharmacy,
Uji, Kyoto-Fu
l-
the first,
l_ (Scheme 1).
4502
Synthesis
Table 1.
of Alkynyliodonium
Salts from Alkynylsilanes
Reaction Entry
1
R
1
la __
n-C8H17
2
la __
n-C8H17
3
lb __
cycle-C6H11
4
lc -_
'gH5
5
lc _...
'gH5
6
Id _..,
'gHgCH2
7
Id -_
'gHgCH2
8
le _...
a)
polymeric
FABMSb
(%)
(m/z)
2a __
70
2a
85
25
2b _."
27
59.5-65
341
64
137-138
311
2c
65
oil
305
2c ..,..,
79
2d __
56
oil
319
3
2dC
53
18
2e _-_
75
oil
333
22 2.5
3 24
b)
Yielda
Peaks corresponding
c)
to (M-BF4)+.
Acetylenic
ketone 7 was also
in 11% yield.
Although 5 rather low.
dioxane,
Product
Time (hr)
C6H5CH2CH2
Isolated yields.
obtained
Method
iodosylbenzene
has been shown to be a useful oxidizing
The low reactivity
nature6
and the very low solubility
dimethylsulfoxide,
silane 1 and iodosylbenzene tetrafluoroborate of iodosylbenzene
of iodosylbenzene
in dichloromethane
or boron trifluoride in the synthesis
toward common organic
Thus no reaction was observed
etc.).
reagent,
may be attributable
solvents
between
at room temperature.
salts 2.
(dichloromethane,
alkynyltrimethyl-
for the activation
When I-trimethylsilyldec-I-yne
(la) was treated with iodosylbenzene (1.6 equiv.) and trieth;loxonium tetrafluoroborate _equiv.) in dichloromethane at room temperature (Method A), 1-decynyl(phenyl)iodonium tetrafluoroborate (1.6 equiv.)
(2a)7 was obtained
directly
in 70% yield.
in the""presence of boron trifluoride
room temperature
followed
by the treatment
etherate
Reaction
of la with
(1.6 equiv.)
(1.6
iodosylbenzene
in-dichloromethane
with excess amounts of aqueous
at
sodium tetrafluoro-
Similarly, alkynylsilanes (lb - e) gave (Method B), also gave rise to 2a in 85% yield. --. __ The results are summarized in Table iodonium salts (2b - e) in good yields. _-. _ Fast atom bombardment mass spectra (FABMS) of the alkynyliodonium tetrafluoroborates 2
borate
the corresponding 1.
is
Triethyloxonium
etherate was found to be essential
of alkynyliodonium
the reactivity
in part to the proposed
showed relatively
abundant fragments corresponding to the cationic portion of the salts. -1R -1 characteristic of the BF4spectra of 2 showed a very large broad band at 1100 - 1000 cm 8 In-the I3 C n.m.r. spectra of 2, a characteristic signal corresponding to the anion. acetylenic
carbon atom bearing
the iodine
(III)
substituent
appeared
at near 6 15:' for
4503
example,
$a_ :
6 15.6, 2! : 6 16.1, 2' : 6 17.9.
Interesting the iodonium
medium
In addition to the formation of in the reaction. 10 was obtained as a minor product in the ketone 7
effect was observed
salt 2d (53%), an acetylenic __ etherate-catalyzed reaction
boron trifluoride
(Entry 7)
dichloromethane". carried
out in dioxane:
trifluoride yield.
etherate
(Method B) of trimethylsilylalkyne
The reaction mode,
Id, on treatment
"in-dioxane"
however,
was much altered
with excess amounts
at room temperature
With 3-(p-methoxyphenyl)-1-trimethylsilylprop-1-yne,
8 was obtained.
The oxidation
to acetylenic
Transient
intermediates
with BF3-activated the formation
produced
of vinyl cations 4,
iodosylbenzene
3, may produce
of the hypervalent
sequence
by the reaction
the alkynyliodonium
16-I-3 species
the ketone 7 in 69%
5 by desilylation
ketone
at all in the reaction
the reaction
la in dioxane. __ Scheme 2 seems to be plausible.
of alkynylsilanes
tetrafluoroborates
(path a).
via
When the reaction
C6H51LOBF3
l
-
3
RCH2-w-;
5
“,>
0SiMe3
.->
16
'gH5
G. F. Koser, in 'The chemistry Rappoport,
BF4-
0
7 R=C6H5
References
2.
RCH2-_,=--I+-C6H5
. ..-.iM'.;
Scheme
1.
NaBF4
'gH5 .
'gH5
4 aq
dioxane (R=Ar)
to 6
z-SiMe3
BF3-Et20
1Path bN
of
shown in
of Id is carried out in dioxane, path b may becGe important and form allenyliodine(II1) __ Nucleophilic attack of oxygen of iodosylbenzene intermediate 6 (R=C6H5) by deprotonation. 11 may afford the ketone 7.
(C6H510)n
was
and boron
a 52% yield of acetylenic
ketones was not observed
In view of these observations,
alkynylsilane
if the reaction
of iodosylbenzene
for 15 hr, afforded
Id "in
of halides,
John Wiley and Sons, Chichester, tosylates
2
3
8 R=p-MeOC6H5
and Notes
pseudo-halides
and azides,'
ed. S. Patai and Z.
1983, Part 2, Ch. 25.
Synthesis
of alkynyl
from phenyl(alkynyl)iodonium
recently:
P. J. Stang and B. W. Surber, J. Am. chern.sm.,
tosylates
was reported
107, ___ 1452 (1985).
4504
3.
F. M. Beringer
4.
G. F. Koser, L. Rebrovic,
5.
(a) T. Takaya, Moriarty, Godoy,
Org.
&em.,
H. Enyo, and E.
Imoto,
J.
30, 1930 (1965). ."_ Org. Chem., 46, 4324
(e) W. Ando, R. Tajima,
(a) H. Siebert J.
Selected
6 O.BB(t, 3;: J 6.8Hz),
2H, J 7.3Hz), 6 14.3(q),
7.52-7.58(m,
15.6(s),
8.
N. N. Greenwood,
9.
The I3 C n.m.r.
J.
SW., 105, -*23, 1685 (1982).
(b)"R. Bell and K. J.
1.20-1.40(m,
720, and 660 cm -I; 'H n.m.r.
IOH), 1.59(quint, and 8.05-B.lO(m,
&em.
spectrum
t), 113.5,
1959, 3811. ____ of I-iodohex-1-yne showed the signal of a-acetylenic and G. E. Maciel,
J.
Phys.
during
the reaction
iodosylbenzene
in the presence
fact the alcohol
9 prepared
silylacethylene,
on treatment
may be considered.
of boron trifluoride
by the reaction
114.l(each
s),
etherate
9 is oxidized
to give the ketone 7.
for 6 hr, afforded
(C6H510)n 'gH5
(Received in Japan 28 May 1985)
l
NysiMe 9
In
with I-lithio-2-trimethyl-
OH A
with
(1.6 equiv.) and boron trifluoride
at rocm temperature
H2°
carbon atom at
of 6 (R=C6H5) with
Alcohol
of benzaldehyde
with iodosylbenzene
in dioxane
-
(CDC13):
69, 1348 (1965).
Chem.,
and B. Wahle, Chem. Ber., 116, 3309 (1983). __ ___ reaction course, nucleophilic substitution
6 (R=C6~5)
2.64(t,
13C n.m.r.
Sot.,
possible
(1.6 equiv.)
2H, J 7.3Hz),
2H).
(400
d).
water produced
etherate
2180, 1120-980,
20.8, 22.6, 27.5, 28.7, 28.8, 29.0, 31.7(each
6 -3.3: D. D. Traficante 10. L. Birkofer
and J.
Chem.
he-h?.,
426, 173 (1976); -__
them.,
2H), 7.64-7.70(m,lH),
132.6, 133.0, and 134.0(each
11. As another
AZZg.
1960, 1209. _..,..,_ data: 2a, i.r.(CHC13):
Tetmhedron
(b) R. M.
(c) R. Muller
Sot.,
spectral
MHZ; CDC13):
22, 1283 ?;981); -_ and T.E. Nemo, J. Am.
Lett.,
and T. Takata,
and M. Handrich, Anorg.
Chem.
(1981).
BUZZ. Chem. Sec. Jpn., "-41, 1032 (1968);
ibid.,..,_ 22, 2361 (1981); (d) J. T. Groves
Morgan, 7.
J.
and R. H. Wettach,
H. Hu, and S. C. Gupta, !?etrahe&on
5786 (1983); 6.
and S. A. Galton,
3
BF3-Et20
7 in 77% yield.