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Solvolysis rates of 4,4-dimethylcyclohexyl tosylate. Evidence on conformational reactivities
Tetrahedron
Letters
No.40,
Pp. 3477-3479,
1969.
Pergamon Press.
Printed
in Great Britain.
SOLVOLYSIS RATES OF 4.4-DIMETHYLCYCLOHEXYLTOSYLATE. EVIDENCEON CONFORMATIONAL REACTIVITIES J.
Eric
Nordlander.
Department
Judith
M. Blank,
and Satya
of Chemistry, Case Western Reserve Cleveland, Ohio 44106
P. Jindal University
(Received in USA 11 June 1969; received in UK for publication 29 July The conformational hexane derivatives first
treated
chair-form state
analysis
such systems
equilibrium
who presented
of -cis-4-substituted
Shiner
and Jewett,
isomer
tions
by Whiting
Recently itself
acetolysis boat
of
cyclohexyl
transition
state
We have carried lysis
rates
of
to provide effect.
7
ficance,
only If its
out a test
-via
the
for
a single
a minor rate
should
substitution,
only
enhancement, system,
conclusion
by virtue however,
as in 1 (or,
3477
effects
the products
a isomers.
that
3a
while
of
transthe
these
reac-
conclusion.
data that
cyclohexyl
tosylate
state. pattern
to be most compatible
by measuring
tosylate
conformers
be substantially
I.
the trans
state,
isotope-effect
the results
for
for
the
with
a twist-
system.
latter
chair
isotope
transition
lb
of ground-
state
for
the Shiner-Jewett
from kinetic
the B-deuterium
parent
chair
of
and Ro
by Kwart and
transition
transition
study
and Eliel
and trans-4-t-butyl
was criticized
from deuterium
cyclo-
and equatorial-sulfonate
the -cis-
the usual
A precise
la
the position
a twist-boat
support
and judged
of
approach
and 4,4-dimethylcyclohexyl
involving
geometry
essentialy
even this
states;
a non-chair
have concluded
have measured
in the unsubstituted
ed by 4,4-dimethyl in Table
for
3b
axial-
using
with
through
has provided
tosylate,
cyclohexyl
For reactions
acids.
acid
This
have inferred
a skewed chair.
and Kwart’
and Finley’
la
to support
solvolyzes
in acetic
transition
of substituted
and Holness
interconverting
tosylates,
hand,
reactions
Yinstein
interpolation,
taken
cyclohexyl
by way of
Perez,
solvolyzes Saunders
evidence
and coworkers4
Mateos,
rapidly
pure models.
brosylate
reacts
topic.
by kinetic
on the other
4-t-butylcyclohexyl
displacement
and the corresponding
was evaluated
series
cis --
in texms of
as conformationally
Takeshita,’
solvolytic
has been a controversial
ground states
substrates
of
1969)
the comparative
in acetic
and trifluoroacetic
the gem-dimethyl of
the relayed
a boat-like
group would be expected
4-axial
transition
distorted
and its
energy
much less
likely,
_21.8
solvo-
alkyl state
steric is
of
correspondingly The results
signiincreas-
are shown
No.40
3478
CH3
H -----OTs
H3c --U
1 Table
I.
Solvolysis
2
Rate Constantsa
Compound
Solvent
CF3C02H Cyclohexyl
OTs
CF3C02H
glacial
acetic
procedure ‘AH’
of
= 26.3
containing
acid
behavior containing
S. Winstein, kcal/mole,
earlier.
is provided 6
The close
trifluoroacetic
tive
causes
evidence chair-chair
with
a non-chair
has also analysis
85.0
1.41
100.0
6.53
25.0
3.50
70.0
0.237
25.0
1.98
anhydride;
conformations accumulated
b
rates J. --
in J.
of such systems
is
titrimetrically 70
by the
812 (1948). acid
rate
deter-
and W. G. Deadman, ibid.,
for
but instead
states
for
cyclohexyl
solvents
90,
both
tosylate,
as different
a slight
substrates;
accelno
as suggested as acetic
and
conclusion.
may thus be discounted
la
M in unbuffered
M in trifluoroacetic
retardation,
the data between
to indicate
1.0
sodium trifluoroacetate;
transition
complex
this
1.0
2735 (1956).
no marked rate
activated
0.05
kl
1.77
0.05
measured
E. Nordlander
, E,
Substrate
Am. -Chem. -.‘_P Sot
d Substrate
chair-form
of
‘C
cases.
and 0.06-M
would seem to secure
Whereas non-chair erable
as described
correspondence
acids’
1.14
and E. Grunwald,
anhydride
grouping
for
in all
cal/deg-mole.
The data are in accord
eration. support
C. Ilanson,
eH. C. Brown and G. Ham, _. ibid
The 4,4-dimethyl
0.271
d
1 wt-% acetic
1 wt-% trifluoroacetic
1590 (1968).
70.0
e
was observed
AS’ = -2.8
mined spectrophotometrically
Relative
d
CH3C02H
aGood first-order
104kl
CH3CO2Hb,c
GTs
4.4-Dimethylcyclohexyl
Temperature,
2,5,7e,lO rather
in the present
that
reactions,
the Winstein-Holness
an oversimplification.
considquantita-
In particular
it
No .40
3479
appears
unjustified
without
causing
appreciable
Acknowledgment. gratefully
to assume that
Support
the 4-t-butyl
ground-
of
this
group provides
or transition-state
work by National
conformational
distortions
Science
of
Foundation
homogeneity
the cyclohexane
ring.
Grant GP-6074 is
acknowledged.
References
(1)
(a)
S. Winstein
and N. J.
and R. S. Ro, ---_ Chem. Ind. Ii. Kwart and T. Takeshita,
(3)
(a)
(4)
Shiner,
and J.
G. Jewett,
N.C.G.
Campbell,
Jr.,
and J.
ibid _.
, 874 1382 (1965).
(5)
J.
L. Mateos,
(6)
W. II. Saunders,
Jr.,
(7)
(a)
and C. A. Lukach,
Ind. ---
(London),
D. T. Hill, Scamehom, (8)
ibid.,
(9)
(a) (b)
(10)
ibid.,
J.
1383 (1965);
g,
H. Parish,
(b)
V. J.
R. M. Southam,
Shiner,
Jr.,
and M. C. Whiting,
1967, 125.
(c)
79,
J.
(1957);
C. Richer,
E. L. Eliel,
Biros,
5986
N. L. Allinger,
6881
R. A. Benkeser
Angyal,
New York,
8&, 3334 (1966);
(1967);
(g)
and E. W.
and E. L. Eliel,
S. J.
Publishers,
J. Am. Chem. z., --81),
(b)
L. A. Pilato,
,‘I Interscience
ibid.,
87, 1384 (1965).
and G. A. 1965,
(f)
F. G. Bordwell
Chem.
p.
115;
C. W. Jefford, and R. G.
90, 6748 (1968).
deductions,
substituents,
more effective
E. L. Eliel
1161 (1964).
J. Am. Chem. E., ---
ibid.,
Analysis
Gunsher,
cited
above,
the pseudo-axial
not been specified.
over
Finley,
(d)
and F. J.
and J.
In previous polar
2007;
“Conformational
E. L. Eliel
86,
and H. Kwart , Chem. Conrm.,
and K. T.
1961,
(b)
355.
ibid. , so, 5414 (1958);
Morrison, (e)
C. Perez,
7J, 5562 (1955);
251.
R. R. Hill,
Chem. z..
Bennet,
1968,
G. Jewett,
J. --
E. L. Eliel
1956,
J. Am. Chem. E., ---
D. M. Muir, B,
J. Am. Chem. E., ---
(London),
(2)
V. J.
Holness.
Presumably
nucleophilic
of
twist-form
transition
or -equatorial
orientation
such a conformation
solvent
states
participation;
in the absence
of the
would be adopted i would thus
leaving
largely
group has to allow
be greatly
preferred
and references
therein;
2, J.
E. Nordlander
A. Streitwieser,
(a)
E.A.S.
Cavell,
(b)
F. Shah-Malak
and W. J. Jr.,
Kelly,
ibid _.,
and G. A. Daffom,
91,
996 (1969),
Tetrahedron
N. B. Chapman, and M. D. Johnson, and J.H.P.
Utley,
Chem. e.,
_, 1967
J. --
Letters, Chem. z.,
69.
1969.
of
1263.
1960, 1413;
Letters
No.40,
Pp. 3477-3479,
1969.
Pergamon Press.
Printed
in Great Britain.
SOLVOLYSIS RATES OF 4.4-DIMETHYLCYCLOHEXYLTOSYLATE. EVIDENCEON CONFORMATIONAL REACTIVITIES J.
Eric
Nordlander.
Department
Judith
M. Blank,
and Satya
of Chemistry, Case Western Reserve Cleveland, Ohio 44106
P. Jindal University
(Received in USA 11 June 1969; received in UK for publication 29 July The conformational hexane derivatives first
treated
chair-form state
analysis
such systems
equilibrium
who presented
of -cis-4-substituted
Shiner
and Jewett,
isomer
tions
by Whiting
Recently itself
acetolysis boat
of
cyclohexyl
transition
state
We have carried lysis
rates
of
to provide effect.
7
ficance,
only If its
out a test
-via
the
for
a single
a minor rate
should
substitution,
only
enhancement, system,
conclusion
by virtue however,
as in 1 (or,
3477
effects
the products
a isomers.
that
3a
while
of
transthe
these
reac-
conclusion.
data that
cyclohexyl
tosylate
state. pattern
to be most compatible
by measuring
tosylate
conformers
be substantially
I.
the trans
state,
isotope-effect
the results
for
for
the
with
a twist-
system.
latter
chair
isotope
transition
lb
of ground-
state
for
the Shiner-Jewett
from kinetic
the B-deuterium
parent
chair
of
and Ro
by Kwart and
transition
transition
study
and Eliel
and trans-4-t-butyl
was criticized
from deuterium
cyclo-
and equatorial-sulfonate
the -cis-
the usual
A precise
la
the position
a twist-boat
support
and judged
of
approach
and 4,4-dimethylcyclohexyl
involving
geometry
essentialy
even this
states;
a non-chair
have concluded
have measured
in the unsubstituted
ed by 4,4-dimethyl in Table
for
3b
axial-
using
with
through
has provided
tosylate,
cyclohexyl
For reactions
acids.
acid
This
have inferred
a skewed chair.
and Kwart’
and Finley’
la
to support
solvolyzes
in acetic
transition
of substituted
and Holness
interconverting
tosylates,
hand,
reactions
Yinstein
interpolation,
taken
cyclohexyl
by way of
Perez,
solvolyzes Saunders
evidence
and coworkers4
Mateos,
rapidly
pure models.
brosylate
reacts
topic.
by kinetic
on the other
4-t-butylcyclohexyl
displacement
and the corresponding
was evaluated
series
cis --
in texms of
as conformationally
Takeshita,’
solvolytic
has been a controversial
ground states
substrates
of
1969)
the comparative
in acetic
and trifluoroacetic
the gem-dimethyl of
the relayed
a boat-like
group would be expected
4-axial
transition
distorted
and its
energy
much less
likely,
_21.8
solvo-
alkyl state
steric is
of
correspondingly The results
signiincreas-
are shown
No.40
3478
CH3
H -----OTs
H3c --U
1 Table
I.
Solvolysis
2
Rate Constantsa
Compound
Solvent
CF3C02H Cyclohexyl
OTs
CF3C02H
glacial
acetic
procedure ‘AH’
of
= 26.3
containing
acid
behavior containing
S. Winstein, kcal/mole,
earlier.
is provided 6
The close
trifluoroacetic
tive
causes
evidence chair-chair
with
a non-chair
has also analysis
85.0
1.41
100.0
6.53
25.0
3.50
70.0
0.237
25.0
1.98
anhydride;
conformations accumulated
b
rates J. --
in J.
of such systems
is
titrimetrically 70
by the
812 (1948). acid
rate
deter-
and W. G. Deadman, ibid.,
for
but instead
states
for
cyclohexyl
solvents
90,
both
tosylate,
as different
a slight
substrates;
accelno
as suggested as acetic
and
conclusion.
may thus be discounted
la
M in unbuffered
M in trifluoroacetic
retardation,
the data between
to indicate
1.0
sodium trifluoroacetate;
transition
complex
this
1.0
2735 (1956).
no marked rate
activated
0.05
kl
1.77
0.05
measured
E. Nordlander
, E,
Substrate
Am. -Chem. -.‘_P Sot
d Substrate
chair-form
of
‘C
cases.
and 0.06-M
would seem to secure
Whereas non-chair erable
as described
correspondence
acids’
1.14
and E. Grunwald,
anhydride
grouping
for
in all
cal/deg-mole.
The data are in accord
eration. support
C. Ilanson,
eH. C. Brown and G. Ham, _. ibid
The 4,4-dimethyl
0.271
d
1 wt-% acetic
1 wt-% trifluoroacetic
1590 (1968).
70.0
e
was observed
AS’ = -2.8
mined spectrophotometrically
Relative
d
CH3C02H
aGood first-order
104kl
CH3CO2Hb,c
GTs
4.4-Dimethylcyclohexyl
Temperature,
2,5,7e,lO rather
in the present
that
reactions,
the Winstein-Holness
an oversimplification.
considquantita-
In particular
it
No .40
3479
appears
unjustified
without
causing
appreciable
Acknowledgment. gratefully
to assume that
Support
the 4-t-butyl
ground-
of
this
group provides
or transition-state
work by National
conformational
distortions
Science
of
Foundation
homogeneity
the cyclohexane
ring.
Grant GP-6074 is
acknowledged.
References
(1)
(a)
S. Winstein
and N. J.
and R. S. Ro, ---_ Chem. Ind. Ii. Kwart and T. Takeshita,
(3)
(a)
(4)
Shiner,
and J.
G. Jewett,
N.C.G.
Campbell,
Jr.,
and J.
ibid _.
, 874 1382 (1965).
(5)
J.
L. Mateos,
(6)
W. II. Saunders,
Jr.,
(7)
(a)
and C. A. Lukach,
Ind. ---
(London),
D. T. Hill, Scamehom, (8)
ibid.,
(9)
(a) (b)
(10)
ibid.,
J.
1383 (1965);
g,
H. Parish,
(b)
V. J.
R. M. Southam,
Shiner,
Jr.,
and M. C. Whiting,
1967, 125.
(c)
79,
J.
(1957);
C. Richer,
E. L. Eliel,
Biros,
5986
N. L. Allinger,
6881
R. A. Benkeser
Angyal,
New York,
8&, 3334 (1966);
(1967);
(g)
and E. W.
and E. L. Eliel,
S. J.
Publishers,
J. Am. Chem. z., --81),
(b)
L. A. Pilato,
,‘I Interscience
ibid.,
87, 1384 (1965).
and G. A. 1965,
(f)
F. G. Bordwell
Chem.
p.
115;
C. W. Jefford, and R. G.
90, 6748 (1968).
deductions,
substituents,
more effective
E. L. Eliel
1161 (1964).
J. Am. Chem. E., ---
ibid.,
Analysis
Gunsher,
cited
above,
the pseudo-axial
not been specified.
over
Finley,
(d)
and F. J.
and J.
In previous polar
2007;
“Conformational
E. L. Eliel
86,
and H. Kwart , Chem. Conrm.,
and K. T.
1961,
(b)
355.
ibid. , so, 5414 (1958);
Morrison, (e)
C. Perez,
7J, 5562 (1955);
251.
R. R. Hill,
Chem. z..
Bennet,
1968,
G. Jewett,
J. --
E. L. Eliel
1956,
J. Am. Chem. E., ---
D. M. Muir, B,
J. Am. Chem. E., ---
(London),
(2)
V. J.
Holness.
Presumably
nucleophilic
of
twist-form
transition
or -equatorial
orientation
such a conformation
solvent
states
participation;
in the absence
of the
would be adopted i would thus
leaving
largely
group has to allow
be greatly
preferred
and references
therein;
2, J.
E. Nordlander
A. Streitwieser,
(a)
E.A.S.
Cavell,
(b)
F. Shah-Malak
and W. J. Jr.,
Kelly,
ibid _.,
and G. A. Daffom,
91,
996 (1969),
Tetrahedron
N. B. Chapman, and M. D. Johnson, and J.H.P.
Utley,
Chem. e.,
_, 1967
J. --
Letters, Chem. z.,
69.
1969.
of
1263.
1960, 1413;