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Synthesis of arylacetylenes from arylcopper compounds
Tetrahedron Letters
?To.
Perga5on Frees.
51, PP 5209 - 5212, 1072.
Frinted in Great Britain.
SYNTHESISOF ARYLACETYLENES FROM ARYLCOPPER COMPOUNDS R. Oliver and D.R.M.
Walton
School of Molecular Sciences, University of Sussex, Brighton BNl SQJ, Sussex, U.K. (Received in UK2 November 1972; accepted for publication Whilst novel and efficient routes to arykcetylenes,
15 November 1972)
ArC =C!H, based upon the construction of
trfple bornis within existing carbon-containing side chains,
1
contbme to supplement older methods of
synthests, the development of protecting groups, a tiirly recent innovation in acetylene chemistry, has generated new approaches to the problem.
2
To date, the latter have uniformly relied upon the
Stephens Castro coupling3 between an aryl iodide and a suitably protected cuprous acetylide, CuC sCR 4 (R = CHrOTHP,* CH(OEt)z, CMezQCH(Me)OEt5)for introduction of the acetylene mofety and may suffer from the disadvantage that elevated temperatures (e.g. refluxing pyridine) are necessary for reaction, furthermore removal of the protecting groups requires several steps. In a conceptually simple procedure, complementary to the Stephens Castro method, we find that a wide range of arylcopper reagents (lJ couple below room temperature with iodoet@nyl(trimethyl)silane (3 (readily available in htgh yield from ClI and MerSiCXXXMer6) to give arylethyrtyl(trimethyl)silanes (2) in good yield.
The protective Me@-
group can then be quantitatively removed by treatment
with alkali7 to give the desired arylacetylene (eq. 1)
Arch I
+ ICECSiMe, 2
---+
ArCECSiMe,
-b
ArCSCH
(1)
z
Best resdts are obtained by adding an ethereal or THF solution of Grtgnard or aryllithtum reagent (1 mole) to a vigorously stirred suspension of freshly prepared CuBr (1-f mole) in ether8 followed by (2J (O+Jmole) in THF. In order to complete coupling, the mixture is maintained initially at 0” 60r 3 hr.
5209
No. 51
5210
then at 20’ for 6 hr.
Isolation
the residual
concentrate
temperature
thus liberating
and unreacted
the arylacetylene
can then be easily
reveal the :oupling conditions of the organocopper
the Grtgnard or organolithium with Me$i(C complex,
= C)#Me,,
Ph$uLi,
of solvent under reduced pressure,
within a few minutes.
desilylated
By-product
by this procedure
described
to be superior
reagent.
10
reagent to a mixture
Experiments
to those involving prior
Use of a catalytic
Me.@i(C= C),SiMe,g
and the resulting butadiyne
removed under reduced pressure.
presumably
11
After removal
is taken up in methanol and treated with dilute aqueous alkali at room
(2J are also conveniently
and iodoacetylene
purification
of (3 is unnecessary.
with phenylcopper
isolation
and
quantity of Cu(I) salt or addition of
of Cu(I) salt and (2) yield much iodobenzene
as a result of halogen-metal
exchange.
together
Use of the cuprate
.m ether or THF gives the same result (eq. 2) whilst soluble phosphine complexes
such as [PhCu(n-Bu,P)jr!
12
yield only 20-30% of PhC= CSiMe,.
PhLi(MgBr)
+
2
--b
Phl
+
LiCsCSiMe,
or Ph&Li /lC”“al
Me$i(CsC)$iMe,
The accompanying not necessarily
optimum,
substituted arylacetylenes required
for conventional
table lists compounds
4-
(3J prepared
are quoted for pure products. are noteworthy syntheses
2
14
reagents. l5
according
to eq. 1.
The preparations
Yields
(based upon Z&)
of 2-, and 3-
in tbat the ketone or aldehyde precursors
most often
are not readily accessible.
The method is timely in view of the detailed reports individual arylcopper
+ (CuCBCSiMe,)
now available
for the preparation
of
5211
No. 51 TABLE ArCXXMe,
(3 compounds prepared from ArCu reagents and ICeCSiMe,
Ar
Yield(%) x
YieId(bX)
Ar
64
3-FC,H,
2-MeC,H,
48
4-Meg
3-MeCvH,
80
2-MefiCH&H,
38
2-MeOC,H,
45
2-MerN-4-MeqHS
20
3 -MeOC,H,
33
2-Naphthyl
47
3-CF&H,
30
2-Furyln
47
2-CF,C$H,
51
2-(5-Me)furyln
61
4-CF,C,H,
38
2-Thieny?
32
C,H,
(2).
29 CaHa
52
n ArCu reagent prepared and initial coupling conducted between -20 and -30’. MEther:pyridine
solvent.
The yield of 2-thienylC =CSiMe, was 90% when the
compound BrC=CSiMer l3
was used in place of (2).
with the bromo reagent were not observed
Increased yields
in couplings with other ArCu
compounds.
Acknowledgements We thank Ciba-Geigy
Ltd.,
for financial support and Rh&e-PouIenc
for a generous gift of
Me.#iC E CSiMe,. REFERENCES 1
P. WieIaud, Helv.chim.Acta,
G
171 (1970);
E.J.
Corey and P.L.
Fuchs, Tetrahedron
Letters,
3769 (1972). 2
D.R.M.
Walton in Protective
Plenum Press;
Groups in Organic Chemistry
London (1973).
(Editor:
J.F.W.
McGmie)
Ch.1;
5212
3
No. 51
RD.
Stephens and C. E. Castro,
Iionwad, A. Malte,
and S. Moje,
4
R.E.
Atkinson, R.F.
5
M.S.
Shvartsberg.
SSSR. Ser.Khim.,
J.Ore.Chem.,
Curtis,
J.Amer.Chem.Soc.,
D.M.
1144 (1970); M.S.
A.N.
6464 (1969).
Taylor,
J.Chem.Soc.(C),
Kozhevnikova and V.N.
Shvartsberg,
1366 (1971); M.S.
Izv. Akad. Nauk SSSR, Ser.Khim.,
s
Jones and J.A.
I. L. Kotlyarevskii,
Nauk SSSR, Ser.Khii.,
24 3313 (1963); C.E. Castro, R. Havlin, V.K.
A.A.
Andrievskii,
Izv.Akad.Nauk
Moroz ati I. L. Kotlyarevskii,
Shvartsberg,
1574 (1971); M.S.
2173 (1969).
L.N.
Izv.Akad.
Bizhan and I. L. Kotlyarevskii,
Shvartsberg
and A.A.
Moroz,
Izv.Akad.
Nauk SSSR, Ser. Khim.,
1582 (1971).
6
D.R.M.
Webb, J.Organometal.Chem.,
7
C. Eaborn and D.R.M.
8
The yield of ArCu is much reduced in some instances if CuBr is added to the Grignard or aryllithium
Walton and M.J.
reagent:
Walton, J. Organometal. Chem., 4, 217 (1965).
M. Nilsson and C. Ullenius,
Acta.
them. Scand..
9
D.R.M.WaltonandF.
10
G. Costa, A. Csmus, L. Gatti and N .Marsich,
11
G.M.
Whitesides,
Chem.Soc., 12
Prepared
a
Waugh, J.Organcmetal.Chem.,
W.F.
Fischer,
s
275 (1972).
J.Organometal.Chem.,
J. San Filippo,
Jr.,
R.W.
5 568 (1966).
Bashe and HO.
House, J.Amer.
4871 (1969). G. B. Kauffman and L.A.
Teter,
Inorg.
9 (1963).
13
II. Buchert and W. Zeil,
14
All products were characterised
15
A.
Spectrochim.Acta.,
Camus and N . Marsich,
J.G. Xoltes,
J.Chem.Soc.(D),
Tetrahedron
Letters,
@.,
Jr,,
2& 2379 (1970).
a
from PhLi and the complex [ICU(~-BLQP)]~:
Syntheses,
3’7, 41 (1972).
93_ 24f (1971);
For a general survey:
l&
1643 (1962).
by IR, proton NMR and mass spectroscopy.
J. Organometal. Chem., 1107 (1970);
M. NiIsson,
2713 (1971); A. Cairncross, A. Cairncross
and W.A.
J.F.
Sym
Normant,
14, 441 (1968); G. vanKoten,
A.J.
Leusinkand
C. Ullenius and 0. Wennerstr~m,
H. Omum and W.A.
Sheppard, J. Amer.Chem.
Sheppard, J.Amer.Chem.Soc., 63 (1972).
G
247 (1971);
?To.
Perga5on Frees.
51, PP 5209 - 5212, 1072.
Frinted in Great Britain.
SYNTHESISOF ARYLACETYLENES FROM ARYLCOPPER COMPOUNDS R. Oliver and D.R.M.
Walton
School of Molecular Sciences, University of Sussex, Brighton BNl SQJ, Sussex, U.K. (Received in UK2 November 1972; accepted for publication Whilst novel and efficient routes to arykcetylenes,
15 November 1972)
ArC =C!H, based upon the construction of
trfple bornis within existing carbon-containing side chains,
1
contbme to supplement older methods of
synthests, the development of protecting groups, a tiirly recent innovation in acetylene chemistry, has generated new approaches to the problem.
2
To date, the latter have uniformly relied upon the
Stephens Castro coupling3 between an aryl iodide and a suitably protected cuprous acetylide, CuC sCR 4 (R = CHrOTHP,* CH(OEt)z, CMezQCH(Me)OEt5)for introduction of the acetylene mofety and may suffer from the disadvantage that elevated temperatures (e.g. refluxing pyridine) are necessary for reaction, furthermore removal of the protecting groups requires several steps. In a conceptually simple procedure, complementary to the Stephens Castro method, we find that a wide range of arylcopper reagents (lJ couple below room temperature with iodoet@nyl(trimethyl)silane (3 (readily available in htgh yield from ClI and MerSiCXXXMer6) to give arylethyrtyl(trimethyl)silanes (2) in good yield.
The protective Me@-
group can then be quantitatively removed by treatment
with alkali7 to give the desired arylacetylene (eq. 1)
Arch I
+ ICECSiMe, 2
---+
ArCECSiMe,
-b
ArCSCH
(1)
z
Best resdts are obtained by adding an ethereal or THF solution of Grtgnard or aryllithtum reagent (1 mole) to a vigorously stirred suspension of freshly prepared CuBr (1-f mole) in ether8 followed by (2J (O+Jmole) in THF. In order to complete coupling, the mixture is maintained initially at 0” 60r 3 hr.
5209
No. 51
5210
then at 20’ for 6 hr.
Isolation
the residual
concentrate
temperature
thus liberating
and unreacted
the arylacetylene
can then be easily
reveal the :oupling conditions of the organocopper
the Grtgnard or organolithium with Me$i(C complex,
= C)#Me,,
Ph$uLi,
of solvent under reduced pressure,
within a few minutes.
desilylated
By-product
by this procedure
described
to be superior
reagent.
10
reagent to a mixture
Experiments
to those involving prior
Use of a catalytic
Me.@i(C= C),SiMe,g
and the resulting butadiyne
removed under reduced pressure.
presumably
11
After removal
is taken up in methanol and treated with dilute aqueous alkali at room
(2J are also conveniently
and iodoacetylene
purification
of (3 is unnecessary.
with phenylcopper
isolation
and
quantity of Cu(I) salt or addition of
of Cu(I) salt and (2) yield much iodobenzene
as a result of halogen-metal
exchange.
together
Use of the cuprate
.m ether or THF gives the same result (eq. 2) whilst soluble phosphine complexes
such as [PhCu(n-Bu,P)jr!
12
yield only 20-30% of PhC= CSiMe,.
PhLi(MgBr)
+
2
--b
Phl
+
LiCsCSiMe,
or Ph&Li /lC”“al
Me$i(CsC)$iMe,
The accompanying not necessarily
optimum,
substituted arylacetylenes required
for conventional
table lists compounds
4-
(3J prepared
are quoted for pure products. are noteworthy syntheses
2
14
reagents. l5
according
to eq. 1.
The preparations
Yields
(based upon Z&)
of 2-, and 3-
in tbat the ketone or aldehyde precursors
most often
are not readily accessible.
The method is timely in view of the detailed reports individual arylcopper
+ (CuCBCSiMe,)
now available
for the preparation
of
5211
No. 51 TABLE ArCXXMe,
(3 compounds prepared from ArCu reagents and ICeCSiMe,
Ar
Yield(%) x
YieId(bX)
Ar
64
3-FC,H,
2-MeC,H,
48
4-Meg
3-MeCvH,
80
2-MefiCH&H,
38
2-MeOC,H,
45
2-MerN-4-MeqHS
20
3 -MeOC,H,
33
2-Naphthyl
47
3-CF&H,
30
2-Furyln
47
2-CF,C$H,
51
2-(5-Me)furyln
61
4-CF,C,H,
38
2-Thieny?
32
C,H,
(2).
29 CaHa
52
n ArCu reagent prepared and initial coupling conducted between -20 and -30’. MEther:pyridine
solvent.
The yield of 2-thienylC =CSiMe, was 90% when the
compound BrC=CSiMer l3
was used in place of (2).
with the bromo reagent were not observed
Increased yields
in couplings with other ArCu
compounds.
Acknowledgements We thank Ciba-Geigy
Ltd.,
for financial support and Rh&e-PouIenc
for a generous gift of
Me.#iC E CSiMe,. REFERENCES 1
P. WieIaud, Helv.chim.Acta,
G
171 (1970);
E.J.
Corey and P.L.
Fuchs, Tetrahedron
Letters,
3769 (1972). 2
D.R.M.
Walton in Protective
Plenum Press;
Groups in Organic Chemistry
London (1973).
(Editor:
J.F.W.
McGmie)
Ch.1;
5212
3
No. 51
RD.
Stephens and C. E. Castro,
Iionwad, A. Malte,
and S. Moje,
4
R.E.
Atkinson, R.F.
5
M.S.
Shvartsberg.
SSSR. Ser.Khim.,
J.Ore.Chem.,
Curtis,
J.Amer.Chem.Soc.,
D.M.
1144 (1970); M.S.
A.N.
6464 (1969).
Taylor,
J.Chem.Soc.(C),
Kozhevnikova and V.N.
Shvartsberg,
1366 (1971); M.S.
Izv. Akad. Nauk SSSR, Ser.Khim.,
s
Jones and J.A.
I. L. Kotlyarevskii,
Nauk SSSR, Ser.Khii.,
24 3313 (1963); C.E. Castro, R. Havlin, V.K.
A.A.
Andrievskii,
Izv.Akad.Nauk
Moroz ati I. L. Kotlyarevskii,
Shvartsberg,
1574 (1971); M.S.
2173 (1969).
L.N.
Izv.Akad.
Bizhan and I. L. Kotlyarevskii,
Shvartsberg
and A.A.
Moroz,
Izv.Akad.
Nauk SSSR, Ser. Khim.,
1582 (1971).
6
D.R.M.
Webb, J.Organometal.Chem.,
7
C. Eaborn and D.R.M.
8
The yield of ArCu is much reduced in some instances if CuBr is added to the Grignard or aryllithium
Walton and M.J.
reagent:
Walton, J. Organometal. Chem., 4, 217 (1965).
M. Nilsson and C. Ullenius,
Acta.
them. Scand..
9
D.R.M.WaltonandF.
10
G. Costa, A. Csmus, L. Gatti and N .Marsich,
11
G.M.
Whitesides,
Chem.Soc., 12
Prepared
a
Waugh, J.Organcmetal.Chem.,
W.F.
Fischer,
s
275 (1972).
J.Organometal.Chem.,
J. San Filippo,
Jr.,
R.W.
5 568 (1966).
Bashe and HO.
House, J.Amer.
4871 (1969). G. B. Kauffman and L.A.
Teter,
Inorg.
9 (1963).
13
II. Buchert and W. Zeil,
14
All products were characterised
15
A.
Spectrochim.Acta.,
Camus and N . Marsich,
J.G. Xoltes,
J.Chem.Soc.(D),
Tetrahedron
Letters,
@.,
Jr,,
2& 2379 (1970).
a
from PhLi and the complex [ICU(~-BLQP)]~:
Syntheses,
3’7, 41 (1972).
93_ 24f (1971);
For a general survey:
l&
1643 (1962).
by IR, proton NMR and mass spectroscopy.
J. Organometal. Chem., 1107 (1970);
M. NiIsson,
2713 (1971); A. Cairncross, A. Cairncross
and W.A.
J.F.
Sym
Normant,
14, 441 (1968); G. vanKoten,
A.J.
Leusinkand
C. Ullenius and 0. Wennerstr~m,
H. Omum and W.A.
Sheppard, J. Amer.Chem.
Sheppard, J.Amer.Chem.Soc., 63 (1972).
G
247 (1971);