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Cycloadditions of thiophene 1,1-dioxides to cyclopropenes: A novel route to alkyl-substituted cycloheptatrienes
Tetrahedron
Letters
No
39,
pp 3755 - 3758,
1973
Pergamon
Press
PrInted
In Great Brltaln
CYCLOADDITIONS OF THIOPHENE l,l-DIOXIDES TO CYCLOPROPENES A NOVEL ROUTE TO ALKYL-SUBSTITUTED D N
CYCLOHEPTATRIENES
Relnhoudt, MISS P. Smael, W.J.M. van Tllborg* and J P KONINKLIJKE/SHELL-LABORATORIUM, (Shell Research B V (Recewed
Vlsser
AMSTERDAM
)
In UK 10 July 1973, accepted for publlcatlon 8 August 1973)
Derlvatlves of cycloheptatrlene have been the SUbJeCt of much study over the past few decades The three methods of their synthesis, VIZ
lsomerlzatlon of blcycloC2 2.1]-2,5-heptadlenes',
pyrolysis of i','l-dlbromobicyclo[4.1.01heptanes2, and addition of methylene carbene to aromatic compounds3'4 all suffer from the disadvantage that they invariably afford rmxtures of lsomeric cycloheptatrlenes,
from which the pure compounds can only be isolated with great dlfflculty
We
here wish to report a new facile synthesis which gives high yields of substituted cycloheptatrlenes not contaminated by lsomerlc products. Treatment of the thlophene l,l-dloxldes5 _la-c - dlenes with inverse electron demand6 - with an excess ' of a suitably substituted cyclopropene (2a_c) at temperatures between -50 and +50 'C In methylene chloride produces the substituted cyclohepta-1,3,5-trienes tatlve yleld8
The reactlon 1s thought to proceed v1& a rate-determining
giving the Duels-Alder adduct 2, subsequent cheletroplc cleavage
10
5a-f In vlrtUally quanti[n's + r2sl cycloaddition9,
of 2 results in the expulsion of
SO2 to afford the cycloheptatriene 2, which 1s probably formed via the corresponding norcaradlene 4' The reactlon 1s analogous to that of 1,2,3-trlphenylcyclopropene yleldlng 1,2,3,4,5,6,7-heptaphenyltricycloC3 off CO to give heptaphenylcycloheptatriene 13
12
2 1 02,4 loct-6-en-8-one, which upon being heated splits In our reactlon, the proposed IntermedIate 3 was not =
detectable by NMR, even at temperatures as low as -60 'C ability of the SO2 fragment
with tetraphenylcyclopentadlenone
14
3755
We attrlbute this to the excellent leaving
3756
No. 39
?_a) R,=R2=Me, R3=H
2~) R,=R2=Me, R3=Rq=R5=R6=H
$a) Rq=Rg=R6=H
b) R,=R2=&-Bu, R3=H
b) Rq=Me, R5=R6=H
b) R,=R2=R4=Me, R3=R5=R6=H
c) R,=R3=L-Bu, R2=H
c) Rt;=Me, Rq=R5=H
c) R,=R2=R6=Me, R3=R4=Rg=H d) R,=R3=g-Bu, R3=R4=R5=R6=" e) R,=R2=L-Bu, R&=Me, R3=R5=R6=H f) R,=R3=4_-Bu, R6=Me, R,=RL=R5=H
As expected 15 , the cycloaddltlon step 1s greatly influenced by sterlc effects whereas 3-methylcyelopropene
(2)
eorrespondlng cycloheptatrlene 2
reacts with 2,!Gdlmethylthlophene
affords the cycloheptatrlene z
l,l-dloxlde (la) to give the
IIIhigh yield, no reaction occurs between 2
cyclopropene 01 3,3-dlmethylcyclopropene.
Slmllarly, 2,4-dl-x-butylthlophene
on treatment with I-methylcyclopropene
does not react with 2,5-dl-t-butylthlophene The synthetic route described above
16
l,l-dloxlde ($,
For example,
and 1,3,3-trlmethyll,l-dloxlde (L)
at 49 “C, but the latter
even on prolonged heating to 60 'C.
allows a wide range of ~somerlca.Lly pure substltuted
cycloheptatrlenes to be isolated in high yield (> 95 %), the only limltlng factor being any excessive sterlc crowdlng II-I the transItIon state of the cycloaddltlon.
No 39
3151
REFERENCES =====3=============
1
W M
Halper, G W
2
D.G
Lindsay and C B
2,
Gaertner, E W
Swift and G E
Polland, Ind
Eng
Chem
See also H E
Reese, Tetrahedron 2l, 1673 (1965)
2,
1131 (1958)
Wlnberg, J
Org
Chem
264 (1959)
3
W
Doerug
and C H
4
E
Muller, H
J
Furukawa, N
Knox, J
Kessler, H
Amer
Chem
Frlcke and W
Kawabata and T
FUJlta,
Backer, Ret
&
2305 (1950), &
Kledalsch, Ann
828 (1951), u,
675, 63 (1964)
See also
J L
Melles and H J
6
P W
Lert and C
7
In order to obtain a high yield of cycloheptatrlenes from the reactlon of &wlth
Amer
Chem
Chun
&
491 (1953)
Sot
g,
6392 (1971)
any excess of the cyclopropene 1s necessary however, requre
297 (1953) J
Nlshlmura,
Tetrahedron 26, 2229 (1970)
5
Trundle, 3
Trav
Sot
_2a-b, hardly
Less reactive thiophene 1,1-dloxldes (=),
a 50 to 100 $ molar excess of cyclopropene, because of the loss of the latter
by concurrent polymerlzatlon 8
Satisfactory IR, 'H-NMR, MS and elemental analysis data were obtained for all compounds
9
The reactlon of 1&wlth
&was
found to follow second order klnetlcs (NMR), z
fu-st order
In each of the reactants 10. R B
Woodward and R
1970, P 11
G
12
M A
2, 13
Hoffmann, "The Conservation of OrbItal Symmetry", Verlag Chemle, Weinhelm,
156
Maler, Angew. Chemie 2, Battlste, Chem
2175 (19631,
Ind
and R
446 (1967) (London) (m),
See also 550
Breslow, G. Ryan and J T
R
Hoffmann, Tetrahedron Letters 1970, 2907
See also Groves,
M A
J
Battlste, J
Am-
Chm
Amer. Chem
Sot
Sot.
92, 988 (igo)
A slmllar reactlon - with N2 as the leaving group - leading to benzo-annelated
cycloheptatrienes
was reported very recently (R E
Comm
Moerck and M A
Battlste, J
Chem
Sot
Chem
1972, 1171)
37.58
iA.
W I_. Mock, J
No 39
Amer. Chem
Sot, 2, -
6918 (1971)
Tetrahedron Letters 1971, 2609, and E W
See also
A.I. Meyers and T
Duck, Research Correspondence, Suppl
Takaya, to Research
ILondon) 8, S 47 (1955) 5
k4.L. Deem, Synthesis m, Vol. 1, Acad
675
See also
Press, New York, 3966, p
G L
Gloss, "Advances ~.nAllcycllc Chemistry",
78.
16. During the preparation of this manuscript two new cycloheptatriene literature. One of them (S. Mlyano and H
Hosh1moto, J
syntheses appeared IIIthe
Chem. Sot. Comm., m,
216)
suffers
from the disadvsntage of being aselectlve with respect to the location of substltuents, the other (J. Stelgel and J
Sauer, Tetrahedron Letters m,
1213) 1s far more limited III scope
Letters
No
39,
pp 3755 - 3758,
1973
Pergamon
Press
PrInted
In Great Brltaln
CYCLOADDITIONS OF THIOPHENE l,l-DIOXIDES TO CYCLOPROPENES A NOVEL ROUTE TO ALKYL-SUBSTITUTED D N
CYCLOHEPTATRIENES
Relnhoudt, MISS P. Smael, W.J.M. van Tllborg* and J P KONINKLIJKE/SHELL-LABORATORIUM, (Shell Research B V (Recewed
Vlsser
AMSTERDAM
)
In UK 10 July 1973, accepted for publlcatlon 8 August 1973)
Derlvatlves of cycloheptatrlene have been the SUbJeCt of much study over the past few decades The three methods of their synthesis, VIZ
lsomerlzatlon of blcycloC2 2.1]-2,5-heptadlenes',
pyrolysis of i','l-dlbromobicyclo[4.1.01heptanes2, and addition of methylene carbene to aromatic compounds3'4 all suffer from the disadvantage that they invariably afford rmxtures of lsomeric cycloheptatrlenes,
from which the pure compounds can only be isolated with great dlfflculty
We
here wish to report a new facile synthesis which gives high yields of substituted cycloheptatrlenes not contaminated by lsomerlc products. Treatment of the thlophene l,l-dloxldes5 _la-c - dlenes with inverse electron demand6 - with an excess ' of a suitably substituted cyclopropene (2a_c) at temperatures between -50 and +50 'C In methylene chloride produces the substituted cyclohepta-1,3,5-trienes tatlve yleld8
The reactlon 1s thought to proceed v1& a rate-determining
giving the Duels-Alder adduct 2, subsequent cheletroplc cleavage
10
5a-f In vlrtUally quanti[n's + r2sl cycloaddition9,
of 2 results in the expulsion of
SO2 to afford the cycloheptatriene 2, which 1s probably formed via the corresponding norcaradlene 4' The reactlon 1s analogous to that of 1,2,3-trlphenylcyclopropene yleldlng 1,2,3,4,5,6,7-heptaphenyltricycloC3 off CO to give heptaphenylcycloheptatriene 13
12
2 1 02,4 loct-6-en-8-one, which upon being heated splits In our reactlon, the proposed IntermedIate 3 was not =
detectable by NMR, even at temperatures as low as -60 'C ability of the SO2 fragment
with tetraphenylcyclopentadlenone
14
3755
We attrlbute this to the excellent leaving
3756
No. 39
?_a) R,=R2=Me, R3=H
2~) R,=R2=Me, R3=Rq=R5=R6=H
$a) Rq=Rg=R6=H
b) R,=R2=&-Bu, R3=H
b) Rq=Me, R5=R6=H
b) R,=R2=R4=Me, R3=R5=R6=H
c) R,=R3=L-Bu, R2=H
c) Rt;=Me, Rq=R5=H
c) R,=R2=R6=Me, R3=R4=Rg=H d) R,=R3=g-Bu, R3=R4=R5=R6=" e) R,=R2=L-Bu, R&=Me, R3=R5=R6=H f) R,=R3=4_-Bu, R6=Me, R,=RL=R5=H
As expected 15 , the cycloaddltlon step 1s greatly influenced by sterlc effects whereas 3-methylcyelopropene
(2)
eorrespondlng cycloheptatrlene 2
reacts with 2,!Gdlmethylthlophene
affords the cycloheptatrlene z
l,l-dloxlde (la) to give the
IIIhigh yield, no reaction occurs between 2
cyclopropene 01 3,3-dlmethylcyclopropene.
Slmllarly, 2,4-dl-x-butylthlophene
on treatment with I-methylcyclopropene
does not react with 2,5-dl-t-butylthlophene The synthetic route described above
16
l,l-dloxlde ($,
For example,
and 1,3,3-trlmethyll,l-dloxlde (L)
at 49 “C, but the latter
even on prolonged heating to 60 'C.
allows a wide range of ~somerlca.Lly pure substltuted
cycloheptatrlenes to be isolated in high yield (> 95 %), the only limltlng factor being any excessive sterlc crowdlng II-I the transItIon state of the cycloaddltlon.
No 39
3151
REFERENCES =====3=============
1
W M
Halper, G W
2
D.G
Lindsay and C B
2,
Gaertner, E W
Swift and G E
Polland, Ind
Eng
Chem
See also H E
Reese, Tetrahedron 2l, 1673 (1965)
2,
1131 (1958)
Wlnberg, J
Org
Chem
264 (1959)
3
W
Doerug
and C H
4
E
Muller, H
J
Furukawa, N
Knox, J
Kessler, H
Amer
Chem
Frlcke and W
Kawabata and T
FUJlta,
Backer, Ret
&
2305 (1950), &
Kledalsch, Ann
828 (1951), u,
675, 63 (1964)
See also
J L
Melles and H J
6
P W
Lert and C
7
In order to obtain a high yield of cycloheptatrlenes from the reactlon of &wlth
Amer
Chem
Chun
&
491 (1953)
Sot
g,
6392 (1971)
any excess of the cyclopropene 1s necessary however, requre
297 (1953) J
Nlshlmura,
Tetrahedron 26, 2229 (1970)
5
Trundle, 3
Trav
Sot
_2a-b, hardly
Less reactive thiophene 1,1-dloxldes (=),
a 50 to 100 $ molar excess of cyclopropene, because of the loss of the latter
by concurrent polymerlzatlon 8
Satisfactory IR, 'H-NMR, MS and elemental analysis data were obtained for all compounds
9
The reactlon of 1&wlth
&was
found to follow second order klnetlcs (NMR), z
fu-st order
In each of the reactants 10. R B
Woodward and R
1970, P 11
G
12
M A
2, 13
Hoffmann, "The Conservation of OrbItal Symmetry", Verlag Chemle, Weinhelm,
156
Maler, Angew. Chemie 2, Battlste, Chem
2175 (19631,
Ind
and R
446 (1967) (London) (m),
See also 550
Breslow, G. Ryan and J T
R
Hoffmann, Tetrahedron Letters 1970, 2907
See also Groves,
M A
J
Battlste, J
Am-
Chm
Amer. Chem
Sot
Sot.
92, 988 (igo)
A slmllar reactlon - with N2 as the leaving group - leading to benzo-annelated
cycloheptatrienes
was reported very recently (R E
Comm
Moerck and M A
Battlste, J
Chem
Sot
Chem
1972, 1171)
37.58
iA.
W I_. Mock, J
No 39
Amer. Chem
Sot, 2, -
6918 (1971)
Tetrahedron Letters 1971, 2609, and E W
See also
A.I. Meyers and T
Duck, Research Correspondence, Suppl
Takaya, to Research
ILondon) 8, S 47 (1955) 5
k4.L. Deem, Synthesis m, Vol. 1, Acad
675
See also
Press, New York, 3966, p
G L
Gloss, "Advances ~.nAllcycllc Chemistry",
78.
16. During the preparation of this manuscript two new cycloheptatriene literature. One of them (S. Mlyano and H
Hosh1moto, J
syntheses appeared IIIthe
Chem. Sot. Comm., m,
216)
suffers
from the disadvsntage of being aselectlve with respect to the location of substltuents, the other (J. Stelgel and J
Sauer, Tetrahedron Letters m,
1213) 1s far more limited III scope