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Ketene thioacetal monosulfonium salts: A two-carbon michael acceptor
TetrahedronLetters No. 43, pp 3757 - 3760, 1974.
KETENE THIOACETAL A TWO-CARBON
PergamonPress. Printed in Great Jritoin.
MONOSULFONIUM
SALTS:
MICHAEL ACCEPTOR 1)
Takeshi Oishi*, Haruko Takechi, and Yoshio Ban Faculty of Pharmaceutical
Sciences, Hokkaido University,
Sapporo, Japan
(3eoeivedin Japrn 15 Auuyat 1974; reoeived in UK for publication18 September1974) It has recently been reported that the ketene thioacetal monooxide(1) used as a two carbon Michael acceptor 2) .
be successfully synthetic a.
studies of natural products,
functional
introduction. of carbon two units bearing
the same type of reaction.
reagent, however,
the vinyl thioethers(3)
expected acetaldehyde a useful
derivatives(4).
the particular
In the model experiments
using this
were also produced along with the
The former involving the vinyl thioether
latant functional group in organic
product when the work-up
In an effort to
found that the ketene thioacetal mono-sulfonium-
salt(2) underwent
moiety,
In connection with the
group into the angular position was required.
achieve this3), we independently
can
condition was appropriately
synthesis, became the major selected, which constitutes
feature of the present method.
CH2=C,
J-Me S-Me
CH==CH-S”‘%Et
The ketene thioacetal veniently
monosulfonium
by S-monoalkylation
followed by base treatment.
salt(a) is expected
to be prepared
of 2-chloromethyl-1,3_dithiane(SP)with Thus,
z prepared
from chloroacetal(6)
Et30+ BF4was treated
with NaH in CH2C12 and the mixture was reacted with ethyl cyanoacetate 3757
con-
in EtOH
No. 43
3758
in the presence of EtONa to afford the alkylthiocyclopropane derivative(8) in 73% yield(crude). Formation of $ obviously shows that 2 is generated during the reaction since the simple vinylsulfonium salt is known to affords the cyclopropane derivatives by the analogous reaction5) ,
EtO, ,C H-C H2Cl Et0 6
CH2Cl -
Et& BF&-
5
2.
7
,CN H2Ckopt
EtS -S e
57 EtO2C
Na, EtOH
CN
0
Now that 2 was proved to be generated, the same procedure6) was applied to the reaction with the active methine compounds.
In these cases, the desired
aldehydes were expected to be produced7) since the initial addition products were incapable of forming cyclopropane derivatives. Actually, the aldehydes(4) were obtained mainly but the vinyl thioethers(3) were also involved in the products(Table 1).
The pathway leading to these compounds may be shown as
follows:
BFi CH2CI
-
LiN(iPrl2
4
The ratio of 1 and $ was subtlyinfluencedby the work-up condition. For example, when the reaction mixture of 2with EtCH(C02Et)3 was ence
Of
Et3i&iCl-, 2 became a major product.
warmed
in
the
pres-
Treatment of 2 with Raney Ni 8)
no.43
3760
REFERENCES 1)
Part X in the series of "Activation of Weak Organic Bases"; T. Oishi, H. Takechi, K. Kamemoto, A part of this work was presented Phosphorous Compounds -I of the Pharmaceutical
February,
Y. Ban, Tetrahedron
Part 1X,
Letters,
ll(1974).
at the 2nd Symposium on Organic Sulfur and 1974, Tokyo, and at the 94th Annual Meeting
Society of Japan, April,
1974, Sendai.
Abstructs
of
Papers, p. 138. 2)
3)
J.L. Herrmann, G.R. Kieczylowski, Tetrahedron
Kieczykowski,
R.F. Romanet, R.H. Schlessinger,
Every attempt
Letters,
4711(1973);
in our system.
Chem. Sot., &&, 1776(1966); E. zers,
Chloroacetal(6) prisms(mp.
P.E. Shaw, J.D. Tauber, J. Am,
J.P. Kutney, W-J. Cretney, P.L. Quesne, B.
j32, 1712(1970).
ibid _.,
is commercially
33-4",after
available.
recrystallization
2 was obtained
from petroleum
of 70%(crude) when dry HCl gas was introduced 1,3-propanedithiol 5)
J. Gosselck,
G.R.
Y. Ban, T. Ohnuma, T. Oishi, unpublished
See also, R.B. Turner, K.H. Ganshirt,
McKague,
R.H.
J.L. Herrmann,
ibid 4715(1973). -.I suitable substituents by alkylation was
to introduce
unsuccessful work.
4)
R.F. Romanet, P.J. Wepplo,
Schlessinger,
as a colorless
ether) in the yield
into a mixture of 6 and
in CHC13.
L. Beress, H. Schenk, G. Schmidt, ggew.
Chem. Intern. Ed.
Engl 2, 596 - -" & 1080(1965); J. Gosselck, L. Beress, H. Schenk, w., (1966); G. Becker, J. Gosselck, Tetrahedron Letters, 4081(1971), and
6)
refe rices cited therin. r" Since the model experiment apprared
to proceed rather slowly and incompletely
Lithium diisopropylamide 7)
showed that abstraction
Hydrolysis
Y. Ban, Tetrahedron
at low temperature,
was used thereafter.
of 1,3-dithiolane
give the corresponding
of HCl from z by NaH
monosulfonium
aldehydes
salts by 3% CuS04 is reported to
in high yield.
Letters, 1085(1972).
T. Oishi, K. Kamemoto,
See also, ref. 11.
8)
R.L. Autrey,
P.W. Scullard, J. Am. Chem. Sot., 90, 4917(1968).
9)
N. Miyamoto,
H. Nozaki, Tetrahedron,
E. Sabourin,
G.J. Mikol, J. Orq. Chem., 2,
D. Fukuoka,
K. Uchimoto,
G. Tsuchhashi, iw.,
G.A. Russell,
2854(1966);
N. Miyamoto,
H. Nozaki, Bull. Chem. Sot. Japgn, g,
S. Mitamura,
2469(1973); -.I ibid
29, 3819(1973);
K. Ogura, Tetrahedron
455(1974).
Letters,
1817(1974);
323 (1973);
KETENE THIOACETAL A TWO-CARBON
PergamonPress. Printed in Great Jritoin.
MONOSULFONIUM
SALTS:
MICHAEL ACCEPTOR 1)
Takeshi Oishi*, Haruko Takechi, and Yoshio Ban Faculty of Pharmaceutical
Sciences, Hokkaido University,
Sapporo, Japan
(3eoeivedin Japrn 15 Auuyat 1974; reoeived in UK for publication18 September1974) It has recently been reported that the ketene thioacetal monooxide(1) used as a two carbon Michael acceptor 2) .
be successfully synthetic a.
studies of natural products,
functional
introduction. of carbon two units bearing
the same type of reaction.
reagent, however,
the vinyl thioethers(3)
expected acetaldehyde a useful
derivatives(4).
the particular
In the model experiments
using this
were also produced along with the
The former involving the vinyl thioether
latant functional group in organic
product when the work-up
In an effort to
found that the ketene thioacetal mono-sulfonium-
salt(2) underwent
moiety,
In connection with the
group into the angular position was required.
achieve this3), we independently
can
condition was appropriately
synthesis, became the major selected, which constitutes
feature of the present method.
CH2=C,
J-Me S-Me
CH==CH-S”‘%Et
The ketene thioacetal veniently
monosulfonium
by S-monoalkylation
followed by base treatment.
salt(a) is expected
to be prepared
of 2-chloromethyl-1,3_dithiane(SP)with Thus,
z prepared
from chloroacetal(6)
Et30+ BF4was treated
with NaH in CH2C12 and the mixture was reacted with ethyl cyanoacetate 3757
con-
in EtOH
No. 43
3758
in the presence of EtONa to afford the alkylthiocyclopropane derivative(8) in 73% yield(crude). Formation of $ obviously shows that 2 is generated during the reaction since the simple vinylsulfonium salt is known to affords the cyclopropane derivatives by the analogous reaction5) ,
EtO, ,C H-C H2Cl Et0 6
CH2Cl -
Et& BF&-
5
2.
7
,CN H2Ckopt
EtS -S e
57 EtO2C
Na, EtOH
CN
0
Now that 2 was proved to be generated, the same procedure6) was applied to the reaction with the active methine compounds.
In these cases, the desired
aldehydes were expected to be produced7) since the initial addition products were incapable of forming cyclopropane derivatives. Actually, the aldehydes(4) were obtained mainly but the vinyl thioethers(3) were also involved in the products(Table 1).
The pathway leading to these compounds may be shown as
follows:
BFi CH2CI
-
LiN(iPrl2
4
The ratio of 1 and $ was subtlyinfluencedby the work-up condition. For example, when the reaction mixture of 2with EtCH(C02Et)3 was ence
Of
Et3i&iCl-, 2 became a major product.
warmed
in
the
pres-
Treatment of 2 with Raney Ni 8)
no.43
3760
REFERENCES 1)
Part X in the series of "Activation of Weak Organic Bases"; T. Oishi, H. Takechi, K. Kamemoto, A part of this work was presented Phosphorous Compounds -I of the Pharmaceutical
February,
Y. Ban, Tetrahedron
Part 1X,
Letters,
ll(1974).
at the 2nd Symposium on Organic Sulfur and 1974, Tokyo, and at the 94th Annual Meeting
Society of Japan, April,
1974, Sendai.
Abstructs
of
Papers, p. 138. 2)
3)
J.L. Herrmann, G.R. Kieczylowski, Tetrahedron
Kieczykowski,
R.F. Romanet, R.H. Schlessinger,
Every attempt
Letters,
4711(1973);
in our system.
Chem. Sot., &&, 1776(1966); E. zers,
Chloroacetal(6) prisms(mp.
P.E. Shaw, J.D. Tauber, J. Am,
J.P. Kutney, W-J. Cretney, P.L. Quesne, B.
j32, 1712(1970).
ibid _.,
is commercially
33-4",after
available.
recrystallization
2 was obtained
from petroleum
of 70%(crude) when dry HCl gas was introduced 1,3-propanedithiol 5)
J. Gosselck,
G.R.
Y. Ban, T. Ohnuma, T. Oishi, unpublished
See also, R.B. Turner, K.H. Ganshirt,
McKague,
R.H.
J.L. Herrmann,
ibid 4715(1973). -.I suitable substituents by alkylation was
to introduce
unsuccessful work.
4)
R.F. Romanet, P.J. Wepplo,
Schlessinger,
as a colorless
ether) in the yield
into a mixture of 6 and
in CHC13.
L. Beress, H. Schenk, G. Schmidt, ggew.
Chem. Intern. Ed.
Engl 2, 596 - -" & 1080(1965); J. Gosselck, L. Beress, H. Schenk, w., (1966); G. Becker, J. Gosselck, Tetrahedron Letters, 4081(1971), and
6)
refe rices cited therin. r" Since the model experiment apprared
to proceed rather slowly and incompletely
Lithium diisopropylamide 7)
showed that abstraction
Hydrolysis
Y. Ban, Tetrahedron
at low temperature,
was used thereafter.
of 1,3-dithiolane
give the corresponding
of HCl from z by NaH
monosulfonium
aldehydes
salts by 3% CuS04 is reported to
in high yield.
Letters, 1085(1972).
T. Oishi, K. Kamemoto,
See also, ref. 11.
8)
R.L. Autrey,
P.W. Scullard, J. Am. Chem. Sot., 90, 4917(1968).
9)
N. Miyamoto,
H. Nozaki, Tetrahedron,
E. Sabourin,
G.J. Mikol, J. Orq. Chem., 2,
D. Fukuoka,
K. Uchimoto,
G. Tsuchhashi, iw.,
G.A. Russell,
2854(1966);
N. Miyamoto,
H. Nozaki, Bull. Chem. Sot. Japgn, g,
S. Mitamura,
2469(1973); -.I ibid
29, 3819(1973);
K. Ogura, Tetrahedron
455(1974).
Letters,
1817(1974);
323 (1973);