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Thermal rearrangement of cage lactones and related compounds — dyotropic rearrangement of cage compounds
Tetrahedron Letters,Vo1.22,No.52,pp 5303-5306,1981 Printed in Great Britain
0040-4039/81/525303-04$02.00/o 01981 Pergamon Press Ltd.
THERMAL REARRANGEMENT OF CAGE LACTONES AND RELATED COMPOUNDS DYOTROPIC REARRANGEMENT OF CAGE COMPOUNDS 'J
Katsuhiro Sat;, Yoshiro Yamashita,2J and Toshio Mukai* Department of Chemistry, Faculty of Science, Tohoku University Aramaki, Sendai 980, Japan
Summary:
Thermolyses of cage lactones (2) _ and their corresponding lactols
(7-Jcause a formal dyotropic rearrangement.
These novel reactions in cage
system are discussed.
It is well known that strained cage compounds undergo various reactions, such as facile ring opening reactions 3J and acid4J or metal ion3aJ ,'J catalyzed rearrangement, involved by its high strain energy.
Although a
dyotropic rearrangement6J 1s generally categorized as a high-energy process because of the simultaneous cleavage of two o-bonds, such a rearrangement would be expected to take place in strained compounds for its high reactivity.
In connection with our previous report on the thermal decarbonylations
of cage ketones (LJTJ we studied thermolyses of cage lactones (2) - and their related compounds, where a formal dyotropic rearrangement occurred instead of the expected decarboxylation reactions. Cage lactones (2J _ were synthesized by the Baeyer-Villiger oxidation of cage ketones (1).
Ketones (l_Jwere unreactive with m-chloroperbenzoic
acid or Ce4+ ion:J but oxidation with peracetic acid gave two kinds of lactones; (2a) mp 186-187 "C, (51% yield), and (3aJ mp 152-153 'C, (21%); (2bJ mp 206-209 OC, (36%), and (3bJ mp 146-147.5 "C, (26%), respectively?) ,loJ The structures of these lactones were proved on the basis of the spectral 11) and chemical evidence that &-lactones (2, - easily rearranged to y-lactones (3J when treated with boron trifluoride!J'8J'12J
The occurrence of such
rearrangement should be ascribed to the relative stability of (3). 5303
The ex-
5304
petted
g-lactones
(2’)
served
reactivity
of
that
of
the
were the
rangement vation
solution at
350
reactions cage
I
for
the
230
(2bJ -
230
values
of
reactions ciable
solvation
usually
symmetrically
thermally
veals thus reason
that the for
the
the C3-C4
more of
not
in
be
from
’
(L’J
the
of
parallel
but
the
reaction
more
of
rear-
and the in
of
(2)
(kcal/molJ
*
acti-
I.14)
Table
AS’
(euJ*
-5.6k5.6
29.5f1.9
-20.4+3.8
out
completely,
that
the
(2bJ -
in
than
as
of
on the of
C-O bond
surely
pair
models
in
the
(6J.
compared
be
the
length
lactones
in
are become
oxygen of (2)-
(5))
causing
This
might
with
that
the
appre-
reactions
reactions lone
negative that
should
(ez+,gJ
depends
(6) -
the
suggest
there
these
of
the
dyotropic
shown
Thermal
molecular
to
These
36.5t2.8
or
state. 6aJ
slopes
[2,2]
rearrangements
rearrangement
ring
a pre-
o-dichlorobenzene
mechanism
the
through
constants
are
ruled
process,
that
cyclobutane
readiness
different
quantitatively.
reactions
by participation
Inspection
bond
is
-
a formal
E,
‘C,
for
transition
forbidden
be noted
bridge.
can
a concerted
should
carbon
thermal
(3)
rate
k (see-‘J
entropies
process
It
be
rearrangement
210-240
process
allowed
atom.
to
first-order
the
10’~
range
via in
(1)
was passed
to
13.2
activation
proceed
for
(2) _
8.54
stepwise
the
(A).
isomerized
considered
thermal
(“CJ
* temperature the
of 13)
The ob-
\
d-lactones
(LJ
The
data
Temp.
(2aJ -
Although
“C,
are
Kinetic
compd.
of
compounds.
parameters
Table
ketone
mixtures.
A
column
of
reaction
reactions
: n=2
thermal
the
(21
When a benzene quarz
in
unsubstituted
a : n = 1 b
novel
detected
Baeyer-Villiger
corresponding
(1)
heated
not
of
the re-
be
a
(2aJ. -
5305
This kind of molecular deformation must be a driving force for dyotropic rearrangements in cage compounds (2).
To gain more informations, the thermolysis was extended to the related compounds.
When the lactols (I), obtained by the reduction of (2)
with LiAlH4, were pyrolyzed at 350 'C by the same method as that used for (21, the rearranged products (8)
were obtained in 30-40% yields.
The structures of (8) - were established by direct comparison with the compounds synthesized by the reduction of (3) with LiA1H4.
2n
(l)a:n=l
2n
(81
b :n=2 Thus, the strained cage system seems to be a good model to search for a new rearrangement, because of the capability to vary molecular deformation by changing the length of the carbon bridge.
Further studies inclu-
ding substituent effects are in progress to elucidate the reaction mechanism in detail.
References and Notes 1.
Organic Thermal Reaction, part 51. Part 50: T. Miyashi, Y. Fujii,
2.
Present address; Department of Applied Chemistry, Faculty of Engineering,
Y. Nishizawa, and T. Mukai, J. Am. Chem. Sot., 103, 725 (1981). Tokushima University, Minami-Josanjima, Tokushima 770, Japan. 3.
a) W. G. Dauben, M. G. Buzzolini, C. H. Schallhorn, and D. L. Whalen, Tetrahedron Lett., 787 (1970). b] H. H. Westberg, E. N. Cain, and S. Masamune, J. Am. Chem. Sot., 9l_, 7512 (1969). c) G. Jones, II and B. R. Ramachandran, J. Org. Chem., g,
798 (1976).
5306
4.
aJ J. C. Barborak and R. Pettit, J. Am. Chem. Sot., 89, 3080 (1967). b) P. R. Schleyer, J. J. Harper, G. L. Dunn, V. J. DiPasquo, and J. R. E. Hoover, ibid., e,
698 (1967).
cj w. L. Dilling and C. E. Reineke, Tetrahedron Lett., 2547 (1967). d) W. L. Dilling, C. E. Reineke, and R. A. Plepys, J. Org. Chem., 2,
2605 (1969).
ej W. L. Dilling, R. A. Plepys, R. D. Kroening, J. Am. Chem. Sot., 91, 3404 (1969). f) W. G. Dauben and L. N. Reitman, J. Org. Chem., 0, 5.
835 (1975).
W. G. Dauben, C. H. Schallhorn, and D. L. Whalen, J. Am. Chem. Sot., 93, 1446 (1971).
6.
a) M. T. Reetz, Adv. Organomet. Chem., 16, 33 (19771, and references sited therein. b) Z. Goldschmidt and S. Antebi, Tetrahedron Lett., 271 (1978).
7. 8.
T. Tezuka, Y. Yamashita, T. Mukai, J. Am. Chem. Sot., 98, 6051 (1976). a) G. Mehta and P. N. Pandey, J. Org. Chem., 5,
953 (1976).
b) K. Hirao, H. Miura, H. Hoshino, and 0. Yonemitsu, Tetrahedron Lett., 3895 (1976). cj 9.
H. Miura, K. Hirao, and 0. Yonemitsu, Tetrahedron, 34, 1805 (1978).
Satisfactory elemental analyses were obtained for all new compounds.
10. The relationship between the structures and reactivities in the BaeyerVilliger reactions of (1) will be reported in detail elsewhere. 11. (2aj: vmax (KBr) 1730 cm-'; 1H NMR(lOO MHz,CDC13) Gppm 0.84(s,3H),1.37 (~3H),1.69(m,lH),2.20(m,lH),2.69-2.99(m,2H~,3.6l-3.8Z(m,2H~,6.9-7.l 0.72 (m,lOH); (3a): vmax(KBr) 1770 cm-'; 'H NMR(lOO MHz,CDC13) 6 (s,3H),O.81js,3H),l.66(dd,lHj,2.3l(dd,lH~,2.33(m,lHj,2.48(m~~fi),2.6l (m,lH~,3.39(m,lHj,6.8-7.4(m,9H),7.69(m,lHj; (2b): vmax(KBr) 1740 cm-'; 1H NMR(lOO MHz,CDC13J 6ppm 0.96(s,3H),1.39(s,3H),1.6-2.l(m,4H),2.17 (m,lH),2.62(dd,lHJ,2.82(dd,lH),3.38(m,lH~,6.9-7.l(m,lOHJ; (3b): vmax (KBrj 1770 cm-'; 'H NMR(lOO MHz,CDC13) Gppm 0.76(s,3H),0.89(s,3HJ, 1.27(dd,lHJ,1.69(dd,lHj,l.7-2.l(m,4Hj,2.Z4(m,lH~,3.25(m,lH~,6.8-7.3 (m,gH),7.64(m,lHJ. 12.
a) R. N. McDonald and G. E. Davis, J. Org. Chem., 34, 1916 (1969). b) G. Biichi and I. M. Goldman, J. Am. Chem. Sot., 79, 4741 (1957).
13. The followings are mainly different points compared with the oxidation of (4); 1) ketones (1J - are not oxidized by m-chloroperbenzoic acid or are not formed, 3) the product ratio of Ce4+ ion , 2) d-lactones (2_'_~ rearranged lactones (3) is greater in the oxidation of (1). See ref. 8. 14. The first-order rate constants and the activation parameters of these reactions were determined by monitoring disappearance of the 6-lactones (21 _ using nmr spectroscopic method. (Received in Japan 9 September 1981)
0040-4039/81/525303-04$02.00/o 01981 Pergamon Press Ltd.
THERMAL REARRANGEMENT OF CAGE LACTONES AND RELATED COMPOUNDS DYOTROPIC REARRANGEMENT OF CAGE COMPOUNDS 'J
Katsuhiro Sat;, Yoshiro Yamashita,2J and Toshio Mukai* Department of Chemistry, Faculty of Science, Tohoku University Aramaki, Sendai 980, Japan
Summary:
Thermolyses of cage lactones (2) _ and their corresponding lactols
(7-Jcause a formal dyotropic rearrangement.
These novel reactions in cage
system are discussed.
It is well known that strained cage compounds undergo various reactions, such as facile ring opening reactions 3J and acid4J or metal ion3aJ ,'J catalyzed rearrangement, involved by its high strain energy.
Although a
dyotropic rearrangement6J 1s generally categorized as a high-energy process because of the simultaneous cleavage of two o-bonds, such a rearrangement would be expected to take place in strained compounds for its high reactivity.
In connection with our previous report on the thermal decarbonylations
of cage ketones (LJTJ we studied thermolyses of cage lactones (2) - and their related compounds, where a formal dyotropic rearrangement occurred instead of the expected decarboxylation reactions. Cage lactones (2J _ were synthesized by the Baeyer-Villiger oxidation of cage ketones (1).
Ketones (l_Jwere unreactive with m-chloroperbenzoic
acid or Ce4+ ion:J but oxidation with peracetic acid gave two kinds of lactones; (2a) mp 186-187 "C, (51% yield), and (3aJ mp 152-153 'C, (21%); (2bJ mp 206-209 OC, (36%), and (3bJ mp 146-147.5 "C, (26%), respectively?) ,loJ The structures of these lactones were proved on the basis of the spectral 11) and chemical evidence that &-lactones (2, - easily rearranged to y-lactones (3J when treated with boron trifluoride!J'8J'12J
The occurrence of such
rearrangement should be ascribed to the relative stability of (3). 5303
The ex-
5304
petted
g-lactones
(2’)
served
reactivity
of
that
of
the
were the
rangement vation
solution at
350
reactions cage
I
for
the
230
(2bJ -
230
values
of
reactions ciable
solvation
usually
symmetrically
thermally
veals thus reason
that the for
the
the C3-C4
more of
not
in
be
from
’
(L’J
the
of
parallel
but
the
reaction
more
of
rear-
and the in
of
(2)
(kcal/molJ
*
acti-
I.14)
Table
AS’
(euJ*
-5.6k5.6
29.5f1.9
-20.4+3.8
out
completely,
that
the
(2bJ -
in
than
as
of
on the of
C-O bond
surely
pair
models
in
the
(6J.
compared
be
the
length
lactones
in
are become
oxygen of (2)-
(5))
causing
This
might
with
that
the
appre-
reactions
reactions lone
negative that
should
(ez+,gJ
depends
(6) -
the
suggest
there
these
of
the
dyotropic
shown
Thermal
molecular
to
These
36.5t2.8
or
state. 6aJ
slopes
[2,2]
rearrangements
rearrangement
ring
a pre-
o-dichlorobenzene
mechanism
the
through
constants
are
ruled
process,
that
cyclobutane
readiness
different
quantitatively.
reactions
by participation
Inspection
bond
is
-
a formal
E,
‘C,
for
transition
forbidden
be noted
bridge.
can
a concerted
should
carbon
thermal
(3)
rate
k (see-‘J
entropies
process
It
be
rearrangement
210-240
process
allowed
atom.
to
first-order
the
10’~
range
via in
(1)
was passed
to
13.2
activation
proceed
for
(2) _
8.54
stepwise
the
(A).
isomerized
considered
thermal
(“CJ
* temperature the
of 13)
The ob-
\
d-lactones
(LJ
The
data
Temp.
(2aJ -
Although
“C,
are
Kinetic
compd.
of
compounds.
parameters
Table
ketone
mixtures.
A
column
of
reaction
reactions
: n=2
thermal
the
(21
When a benzene quarz
in
unsubstituted
a : n = 1 b
novel
detected
Baeyer-Villiger
corresponding
(1)
heated
not
of
the re-
be
a
(2aJ. -
5305
This kind of molecular deformation must be a driving force for dyotropic rearrangements in cage compounds (2).
To gain more informations, the thermolysis was extended to the related compounds.
When the lactols (I), obtained by the reduction of (2)
with LiAlH4, were pyrolyzed at 350 'C by the same method as that used for (21, the rearranged products (8)
were obtained in 30-40% yields.
The structures of (8) - were established by direct comparison with the compounds synthesized by the reduction of (3) with LiA1H4.
2n
(l)a:n=l
2n
(81
b :n=2 Thus, the strained cage system seems to be a good model to search for a new rearrangement, because of the capability to vary molecular deformation by changing the length of the carbon bridge.
Further studies inclu-
ding substituent effects are in progress to elucidate the reaction mechanism in detail.
References and Notes 1.
Organic Thermal Reaction, part 51. Part 50: T. Miyashi, Y. Fujii,
2.
Present address; Department of Applied Chemistry, Faculty of Engineering,
Y. Nishizawa, and T. Mukai, J. Am. Chem. Sot., 103, 725 (1981). Tokushima University, Minami-Josanjima, Tokushima 770, Japan. 3.
a) W. G. Dauben, M. G. Buzzolini, C. H. Schallhorn, and D. L. Whalen, Tetrahedron Lett., 787 (1970). b] H. H. Westberg, E. N. Cain, and S. Masamune, J. Am. Chem. Sot., 9l_, 7512 (1969). c) G. Jones, II and B. R. Ramachandran, J. Org. Chem., g,
798 (1976).
5306
4.
aJ J. C. Barborak and R. Pettit, J. Am. Chem. Sot., 89, 3080 (1967). b) P. R. Schleyer, J. J. Harper, G. L. Dunn, V. J. DiPasquo, and J. R. E. Hoover, ibid., e,
698 (1967).
cj w. L. Dilling and C. E. Reineke, Tetrahedron Lett., 2547 (1967). d) W. L. Dilling, C. E. Reineke, and R. A. Plepys, J. Org. Chem., 2,
2605 (1969).
ej W. L. Dilling, R. A. Plepys, R. D. Kroening, J. Am. Chem. Sot., 91, 3404 (1969). f) W. G. Dauben and L. N. Reitman, J. Org. Chem., 0, 5.
835 (1975).
W. G. Dauben, C. H. Schallhorn, and D. L. Whalen, J. Am. Chem. Sot., 93, 1446 (1971).
6.
a) M. T. Reetz, Adv. Organomet. Chem., 16, 33 (19771, and references sited therein. b) Z. Goldschmidt and S. Antebi, Tetrahedron Lett., 271 (1978).
7. 8.
T. Tezuka, Y. Yamashita, T. Mukai, J. Am. Chem. Sot., 98, 6051 (1976). a) G. Mehta and P. N. Pandey, J. Org. Chem., 5,
953 (1976).
b) K. Hirao, H. Miura, H. Hoshino, and 0. Yonemitsu, Tetrahedron Lett., 3895 (1976). cj 9.
H. Miura, K. Hirao, and 0. Yonemitsu, Tetrahedron, 34, 1805 (1978).
Satisfactory elemental analyses were obtained for all new compounds.
10. The relationship between the structures and reactivities in the BaeyerVilliger reactions of (1) will be reported in detail elsewhere. 11. (2aj: vmax (KBr) 1730 cm-'; 1H NMR(lOO MHz,CDC13) Gppm 0.84(s,3H),1.37 (~3H),1.69(m,lH),2.20(m,lH),2.69-2.99(m,2H~,3.6l-3.8Z(m,2H~,6.9-7.l 0.72 (m,lOH); (3a): vmax(KBr) 1770 cm-'; 'H NMR(lOO MHz,CDC13) 6 (s,3H),O.81js,3H),l.66(dd,lHj,2.3l(dd,lH~,2.33(m,lHj,2.48(m~~fi),2.6l (m,lH~,3.39(m,lHj,6.8-7.4(m,9H),7.69(m,lHj; (2b): vmax(KBr) 1740 cm-'; 1H NMR(lOO MHz,CDC13J 6ppm 0.96(s,3H),1.39(s,3H),1.6-2.l(m,4H),2.17 (m,lH),2.62(dd,lHJ,2.82(dd,lH),3.38(m,lH~,6.9-7.l(m,lOHJ; (3b): vmax (KBrj 1770 cm-'; 'H NMR(lOO MHz,CDC13) Gppm 0.76(s,3H),0.89(s,3HJ, 1.27(dd,lHJ,1.69(dd,lHj,l.7-2.l(m,4Hj,2.Z4(m,lH~,3.25(m,lH~,6.8-7.3 (m,gH),7.64(m,lHJ. 12.
a) R. N. McDonald and G. E. Davis, J. Org. Chem., 34, 1916 (1969). b) G. Biichi and I. M. Goldman, J. Am. Chem. Sot., 79, 4741 (1957).
13. The followings are mainly different points compared with the oxidation of (4); 1) ketones (1J - are not oxidized by m-chloroperbenzoic acid or are not formed, 3) the product ratio of Ce4+ ion , 2) d-lactones (2_'_~ rearranged lactones (3) is greater in the oxidation of (1). See ref. 8. 14. The first-order rate constants and the activation parameters of these reactions were determined by monitoring disappearance of the 6-lactones (21 _ using nmr spectroscopic method. (Received in Japan 9 September 1981)