Kinetics and mechanism of the aminolysis of phenyl cyclopropanecarboxylates in acetonitrile

Article abstract of DOI:10.1039/a801540f

Kinetic studies of the reaction of Z-phenyl cyclopropanecarboxylates with X-benzylamines in acetonitrile at 55.0 °C have been carried out. The reaction proceeds by a stepwise mechanism in which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, T^±, with a hydrogen-bonded four-center type transition state (TS). These mechanistic conclusions are drawn based on (i) the large magnitude of ρ_X and ρ_Z, (ii) the normal kinetic isotope effects (K_H/k_D > 1.0) involving deuterated benzylamine nucleophiles, (iii) the positive sign of ρ_XZ and the larger magnitude of ρ_XZ than that for normal S_N2 processes, and lastly (iv) adherence to the reactivity-selectivity principle (RSP) in all cases.

Full text of DOI:10.1039/a801540f

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Kinetics and mechanism of the aminolysis of phenyl
cyclopropanecarboxylates in acetonitrile
Han Joong Koh,a Chul Ho Shin,b Hai Whang Leec and Ikchoon Lee*,c
a Department of Science Education, Chonju National University of Education, Chonju 560-757,
Korea
b Department of Chemistry, Chonbuk National University, Chonju 560-756, Korea
c Department of Chemistry, Inha University, Inchon 402-751, Korea
Kinetic studies of the reaction of Z-phenyl cyclopropanecarboxylates with X-benzylamines in
acetonitrile at 55.0 ЊC have been carried out. The reaction proceeds by a stepwise mechanism in
which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, T ,
with a hydrogen-bonded four-center type transition state (TS). These mechanistic conclusions
are drawn based on (i) the large magnitude of ñX and ñZ, (ii) the normal kinetic isotope effects
(kH/kD > 1.0) involving deuterated benzylamine nucleophiles, (iii) the positive sign of ñXZ and
the larger magnitude of ñXZ than that for normal SN2 processes, and lastly (iv) adherence to
the reactivity–selectivity principle (RSP) in all cases.
group (Z), are opposite (ρXY > 0 and ρYZ < 0)1,7 to those for
Introduction
normal SN2 processes or for acyl transfers with rate-limiting
formation of the tetrahedral intermediate, T (ρXY > 0 and
ρYZ < 0). The sign of ρXZ is always positive in the stepwise
mechanism with rate-limiting decomposition of the tetrahedral
intermediate, T , (Scheme 1), whereas in the concerted SN2
Aminolyses of ester compounds have been the subject of
numerous kinetic studies.1–3 Most of these reactions are nucleo-
philic and in some of them curved Brønsted-type plots have
been found, which have been explained by the existence of at
least one tetrahedral intermediate in the reaction path and a
change in the rate-determining step.2
O
In contrast to the generally accepted view of the past 20–30
years that nucleophilic substitution reactions at a carbonyl
group involve almost invariably the tetrahedral intermediate, it
has been shown recently that some acyl transfer reactions can
involve a concerted mechanism.4 Most of these studies are,
however, carried out in protic solvents, typically in aqueous
solution. Recent results of aminolysis studies of esters5 and
acyl halides2a,6 have shown that the similar mechanism involv-
ing the tetrahedral intermediate also applies in aprotic solvents
like acetonitrile.
XNH2
+
R
k–a ka
_
C
OC6H4Z
O
C
O
C
kb
R
OC6H4Z
R
+
–OC6H4Z
+
+
XNH2
XNH2
±
T
The reactions of Z-phenyl Y-benzoates (I),1b ethyl Z-phenyl
carbonates (II)1i and Z-phenyl 2-furoates (III)1g with X-benzyl-
+
_
fast
H
O
C
O
C
YC6H4
O
C6H4Z
CH3CH2O
O
C6H4Z
-
δ
I
II
O
C
-
δ
O
R
OC6H4Z
_
O
C
HOC6H4Z
R
C
+
δ
+
δ
O
C6H4Z
X
N
H
O
XNH
H
III
Scheme 1
amines in acetonitrile at 55.0 ЊC have been found to proceed
via a tetrahedral intermediate, T , with its breakdown as the
rate-determining step.
reactions it can be either positive or negative.1,8 (iii) The magni-
tudes of ρXY, ρYZ and ρXZ are greater than those for normal SN2
processes.1,8 (iv) The deuterium kinetic isotope effects involving
deuterated nucleophiles are normal, kH/kD > 1.0.1,5,8 (v) The
RSP holds, i.e. a faster rate is accompanied by a lower selectiv-
ity.9 (vi) There is a small positive enthalpy of activation, ∆H‡,
and a large negative entropy of activation, ∆S‡.1e,2c,10
The following mechanistic criteria are proposed theoretic-
ally7 and found experimentally1–5 to apply to the stepwise
mechanism with rate-limiting expulsion of the leaving group in
the aminolysis of esters and carbonates. (i) The magnitudes of
the reaction constants ρX (ρnuc) and ρZ (ρ1g) [and also the corre-
sponding βX (βnuc) and βZ (β1g)] values, based on the macro-
scopic rate constants, k2 = (ka/kϪa)kb = Kkb for the simplified
reaction given by Scheme 1, are large.1,7 (ii) The signs of cross-
interaction constants, ρij in eqn. (1),8 where i and j are the sub-
stituents on the nucleophile (X), the substrate (Y) or the leaving
log (kij/kHH) = ρiσi ϩ ρjσj ϩ ρijσiσj
∂2log kXZ ∂ρZ ∂ρX
(1a)
(1b)
ρXZ
=
=
=
∂σX ∂σZ ∂σX ∂σZ
J. Chem. Soc., Perkin Trans. 2, 1998
1329

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Table 1 Second-order rate constants, kN (103 dm3 molϪ1
acetonitrile at 55.0 ЊC
s
Ϫ1), for the reactions of Z-phenyl cyclopropanecarboxylates with X-benzylamines in
Z
a
b
X
m-CN
m-NO2
p-CH3CO
p-CN
20.1
p-NO2
ρZ
βZ
p-CH3O
p-CH3
2.09
5.01
15.1
116
2.41 0.08
2.47 0.01
Ϫ1.10
Ϫ1.10
(30.2)c
70.8
1.23
0.911d
0.675e
2.95
7.41
15.1
52.8
39.4
(27.5)
54.1
(22.9)
23.4
(16.2)
14.4
10.4
H
0.562
0.170
1.41
4.17
1.58
7.08
2.75 0.06
2.99 0.06
Ϫ1.27
Ϫ1.37
p-Cl
m-Cl
0.447
2.88
0.0977
0.0688
0.0485
0.288
0.832
2.01
2.97 0.02
Ϫ1.35
7.56
f
ρX
Ϫ2.10 0.02
Ϫ1.97 0.04
Ϫ1.88 0.05
Ϫ1.63 0.04
Ϫ1.36 0.05
ρXZ g = 1.06 0.17
h
βX
2.09 0.02
1.94 0.03
1.78 0.03
1.66 0.04
1.33 0.05
a The σϪ values were taken from H. H. Jaffe, Chem. Rev., 1953, 53, 191. Correlation coefficients were better than 0.994 in all cases. b The pKa values
were taken from A. Albert and E. P. Serjeant, The Determination of Ionization Constants, 3rd edn., 1984, p. 45. Correlation coefficients were better
than 0.976 in all cases. Z = p-CH3CO and m-CN were excluded. c The values in parentheses are those for the corresponding reactions of phenyl
benzoates. d At 45.0 ЊC. e At 35.0 ЊC. f The σ values were taken from D. H. McDaniel and H. C. Brown, J. Org. Chem., 1958, 23, 420. Correlation
coefficients were better than 0.994 in all cases. g Correlation coefficient was 0.997. h The pKa values were taken from A. Fischer, W. J. Galloway and
J. Vaughan, J. Chem. Soc., 1964, 3588. Correlation coefficients were better than 0.992 in all cases. X = p-CH3O were excluded from the Brønsted
plot for βX (benzylamine) due to an unreliable pKa value listed.
Besides a change in the reaction medium from protic to
aprotic, a change in the acyl group (R) to a stronger electron
acceptor is also known to favor the stepwise mechanism with
rate-limiting decomposition of the tetrahedral intermediate,
T (Scheme 1).2b,7,11
In the present work we carried out a kinetic and mechanistic
study of the reactions of cyclopropanecarboxylate with benzyl-
amines in acetonitrile at 55.0 ЊC. We varied the two substituents
X and Z on the nucleophile and leaving group, respectively
[eqn. (2)].
the phenyl cyclopropanecarboxylates. The solvolysis was not
observed under the reaction conditions (k0 ≅ 0). The second-
order rate constants for aminolysis (kN) were obtained from the
slopes of the plots [eqn. (4)]. These values, together with the
Hammett [ρX(ρnuc) and ρZϪ(ρ1gϪ)] and Brønsted [βX (βnuc) and
βZ (β1g)] coefficients, are shown in Table 1.
Rates are faster with a stronger nucleophile (δσX < 0) and
nucleofuge (δσZ > 0) as is expected from a typical nucleophilic
substitution reaction. The rates are ~2–3 times faster than those
for phenyl benzoates1b (given in parentheses) under the same
reaction conditions. This could be due to a larger electron
donating resonance of the phenyl ring (σR = Ϫ0.28)1g,12 relative
to that of the cyclopropane ring (σR = Ϫ0.15)1g,12 in the corre-
sponding substrates.
O
C
OC6H4Z
+
XC H CH NH
2
6
4
2
2
The results in Table 1 reveal that the magnitude of ρX is quite
large; it ranges from ca. Ϫ4 to Ϫ6 (the corresponding values are
Ϫ0.76 to Ϫ1.90,1b Ϫ2.85 to Ϫ4.831i and Ϫ2.94 to Ϫ5.381g for
the I, II and III series, respectively) after allowing for a fall-off
factor of 2.89 for the non-conjugating intervening group CH2
in benzylamine (relative to aniline). This large magnitude of
ρX(ρnuc) is also reflected in the similarly large magnitude of
βX(βnuc) = 1.33–2.09 (the corresponding values are 0.25–0.70,1b
1.08–1.711i and 1.06–1.831g for the I, II and III series, respec-
tively), although the pKa values used in the determination of βX
for benzylamines are for those in water, so that the βX values are
not quite reliable. These large magnitudes of ρX and βX are
indicative of a stepwise mechanism with a rate-limiting break-
down of a zwitterionic tetrahedral intermediate, T 1,3,5 (Scheme
1). The importance of the leaving group departure in the
rate-determining step is reflected in the better Hammett corre-
MeCN
55.0 °C
(2)
O
+
NHCH2C6H4X
XC6H4CH2NH3+ –OC6H4Z
C
X = p-CH3O, p-CH3, H, m-Cl or p-Cl
X = m-CN, m-NO2, p-CH3CO, p-CN or p-NO2
Not much is known about the aminolysis of small ring cyclo
ester compounds. Therefore, kinetic studies have been carried
out in order to clarify the mechanism of the reactions of the
cyclopropyl ester compounds. To our knowledge there have
been no reports of the kinetics of the aminolysis of phenyl
cyclopropanecarboxylates.
Ϫ
Ϫ
Results and discussion
The reactions were first-order (kobs) in both benzylamine, [N],
and substrates, [S], eqns. (3) and (4), under the experimental
lations with σZ than with σZ and large magnitude of ρZ
(= 2.41–2.97) suggesting a strong negative charge development
in the phenoxide leaving group with a relatively large extent
of bond cleavage in the TS (βZ = Ϫ1.10 to Ϫ1.35). These large
Ϫ
ρZ (βZ) values are again indicative of the stepwise mechanism
Rate = kobs[S]
(3)
(4)
with a rate-limiting breakdown of a zwitterionic tetrahedral
intermediate, T (Scheme 1).1,3,5
kobs = k0 ϩ kN[N]
The kN values in Table 1 are subjected to multiple regression
analysis using eqn. (1). The cross-interaction constant ρXY
obtained was positive and large at 1.06. This provides further
strong support for the proposed mechanism.1,7 Since an elec-
conditions. Plots of kobs against benzylamine concentration
were linear in accordance with eqn. (4), where k0 and kN are the
rate coefficients for solvolysis and aminolysis, respectively, of
1330
J. Chem. Soc., Perkin Trans. 2, 1998

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Table 2 Kinetic isotope effects on the second-order rate constants (kN) for the reactions of Z-phenyl cyclopropanecarboxylates with deuterated
X-benzylamines (XC6H4CH2ND2) in acetonitrile at 55.0 ЊC
X
Z
kH/103 dm3 molϪ1 sϪ1
kD/103 dm3 molϪ1 sϪ1
kH/kD
H
H
H
H
p-NO2
p-CN
p-CH3CO
m-NO2
m-CN
p-CN
p-CN
p-CN
p-CN
54.1 0.3a
7.08 0.04
4.17 0.05
1.41 0.03
0.562 0.003
20.1 0.5
15.1 0.2
2.88 0.04
2.01 0.03
44.7 0.3a
5.49 0.05
3.16 0.03
1.01 0.006
0.380 0.006
16.2 0.4
12.0 0.3
2.15 0.03
1.46 0.03
1.21 0.01a
1.29 0.01
1.32 0.02
1.40 0.03
1.48 0.02
1.24 0.04
1.26 0.04
1.34 0.03
1.38 0.04
H
p-CH3O
p-CH3
p-Cl
m-Cl
a Standard deviation.
Table 3 Activation parametersa for the reactions of Z-phenyl cyclo-
tron acceptor in the nucleophile, δσX > 0 (and in the nucleofuge,
δσZ > 0) leads to an increase in ρZ, δρZ > 0 (δρX > 0), ρXZ is
positive [eqn. (1b)]. We note that the rate increase is invariably
accompanied by a decrease in the magnitude of ρ (ρX or ρZϪ),
and hence the RSP holds.9,14 Adherence to the RSP is con-
sidered another criterion for the stepwise mechanism with rate-
limiting expulsion of the leaving group (phenoxides).9,14
We determined kinetic isotope effects (kH/kD) in acetonitrile
for the reactions of Z-phenyl cyclopropanecarboxylates with
X-benzylamines deuterated on the nitrogen (XC6H4CH2ND2)
(Table 2). We note that the kH/kD values are all greater than one,
kH/kD > 1.0, indicating that the rate-determining step is not a
simple concerted SN2 process (TS1), or a stepwise mechanism
propanecarboxylates with X-benzylamines in acetonitrile
X
Z
∆H‡/kcal molϪ1
Ϫ∆S‡/cal molϪ1 KϪ1
p-CH3
p-CH3
m-Cl
m-CN
p-NO2
m-CN
p-NO2
5.39 0.01
6.50 0.01
6.41 0.02
5.80 0.01
56
44
58
49
1
1
1
1
m-Cl
a Calculated by the Eyring equation. Errors shown are standard
deviations.
Activation parameters for the reactions of phenyl cyclo-
propanecarboxylates with benzylamines are shown in Table 3.
The values of ∆H‡ ∆S‡ were obtained from the slope and
intercept, respectively, of Eyring plots, by least-squares analy-
sis. Although the relatively low positive ∆H‡ and large negative
∆S‡ values are in line with the stepwise mechanism,1e,2c,10
they can also be interpreted as supportive of a concerted
mechanism.
O
C
‡
δ+
δ–
OC6H4Z
XC6H4CH2NH2
TS1
Castro et al.15 have argued and Lee et al. have shown theo-
retically7c that a tetrahedral intermediate cannot be formed for
a substrate with a strong electron donor acyl group, i.e. C2H5O,
with a rate-limiting formation of a tetrahedral intermediate
(TS2) since in such cases inverse kinetic isotope effect, kH/kD, are
due to the kinetic instability brought about by the large values
O–
2k,m,15
of ka and kb
(Scheme 1). Thus a concerted mechanism is
+
XC6H4CH2NH2
C
OC6H4Z
enforced.2k,m,15 However, for the reaction systems investigated in
this work, the cyclopropane group has a relatively low reson-
ance donor effect (σR = Ϫ0.15 vs. Ϫ0.44 for C2H5O group)12 so
that the T intermediate seems to be stable enough to lead to
the proposed stepwise mechanism.
TS2
In summary, the reactions of phenyl cyclopropanecarboxyl-
ates with benzylamines in acetonitrile proceed by a stepwise
mechanism in which the rate-determining step is the breakdown
of the zwitterionic tetrahedral intermediate with a hydrogen-
bonded four-center type TS.
These mechanistic conclusions are drawn based on (i) the
large magnitude of ρX and ρZ, (ii) the normal kinetic isotope
effects (kH/kD > 1.0) involving deuterated benzylamine nucleo-
philes, (iii) a small positive enthalpy of activation, ∆H‡, and
a large negative entropy of activation, ∆S‡, (iv) the positive
sign of ρXZ and the larger magnitude of ρXZ than that for
normal SN2 processes, and lastly (v) adherence to the RSP in
all cases.
expected due to an increase in the N᎐H vibrational frequency as
a result of steric congestion of the N᎐H moiety in the bond
making step. The kinetic isotope effects observed, kH/kD = 1.21–
1.48, are larger than those expected from a stepwise acyl trans-
fer mechanism, but are smaller than normal primary kinetic
isotope effects.1 Close examination of the data in Table 2 reveals
that the kH/kD values are smaller for a stronger nucleophile and
nucleofuge. Since in the intermediate, T , both a stronger
nucleophile and nucleofuge facilitate the leaving group depart-
ure, less assistance is needed in the rate-limiting leaving group
departure by the hydrogen bonding of the amine hydrogen.1f,h,6c
In addition, they also attest to the adherence to the RSP, i.e.
a faster rate (by a stronger nucleophile and/or nucleofuge)
leads to a lower selectivity, kH/kD.9 We therefore conclude that
the TS is of a four-center type (TS3) in which hydrogen
bonding of an amine hydrogen atom occurs to the departing
phenoxide.
Experimental
Materials
Merck GR acetonitrile was used after three distillations. The
benzylamine nucleophiles, Aldrich GR, were used without
further purification. Preparation of deuterated benzylamines
were as described previously.1 The analysis (NMR and GC
mass spectroscopy) of the deuterated benzylamines showed
more than 99% deuterium content, so that no corrections to
kinetic isotope effects for incomplete deuteration were made.
J values are given in Hz. Phenyl cyclopropanecarboxylates
δ–
‡
O
δ–
C
OC6H4Z
δ+
δ+
XC6H4CH2
N
H
H
TS3
J. Chem. Soc., Perkin Trans. 2, 1998
1331

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were prepared by reacting phenols with cyclopropanecarbonyl
chloride. The substrates synthesized were confirmed by spectral
analyses as follows.
p-Cyanophenyl cyclopropanecarboxylate. Mp 41–42 ЊC;
δH(400 MHz, CDCl3), 7.68 (2H, d, m-H, J 8.79), 7.24 (2H, d, o-
H, J 8.80), 1.82–1.89 (1H, m, CH), 1.05–1.21 (4H, m, 2CH2);
νmax(KBr)/cmϪ1 2900 (CH, aromatic), 2300 (CN), 1720 (C᎐O);
m/z = 187 (Mϩ) (Calc. for C11H9NO2: C, 65.8; H, 4.80. Found:
C, 65.7; H, 4.81%).
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m-Cyanophenyl cyclopropanecarboxylate. Mp 41–42 ЊC;
δH(400 MHz, CDCl3), 7.69 (1H, d, p-H, J 8.70), 7.60 (1H, t,
o-H, J 2.20), 7.29 (1H, t, m-H, J 8.06), 7.20 (1H, d, o-H, J 5.86),
1.82–1.89 (1H, m, CH), 1.05–1.21 (4H, m, 2CH2); νmax(KBr)/
cmϪ1 2900 (CH, aromatic), 2300 (CN), 1720 (C᎐O); m/z = 187
᎐
(Mϩ) (Calc. for C11H9NO2: C, 65.8; H, 4.80. Found: C, 65.7;
H, 4.79%).
p-Nitrophenyl cyclopropanecarboxylate. Mp 102–103 ЊC;
δH(400 MHz, CDCl3), 7.68 (2H, d, m-H, J 8.79), 7.24 (2H, d,
o-H, J 8.80), 1.83–1.89 (1H, m, CH), 1.04–1.22 (4H, m, 2CH2),
νmax(KBr)/cmϪ1 2900 (CH, aromatic), 1720 (C᎐O); m/z = 207
᎐
(Mϩ) (Calc. for C10H9NO4: C, 58.0; H, 4.35. Found: C, 58.1;
H, 4.36%).
m-Nitrophenyl cyclopropanecarboxylate. Mp 52–53 ЊC;
δH(400 MHz, CDCl3), 8.10 (1H, d, p-H, J 8.06), 8.01 (1H, o-H,
J 2.20), 7.55 (1H, t, m-H, J 8.06), 7.46 (1H, d, o-H, J 5.86),
1.83–1.89 (1H, m, CH), 1.04–1.22 (4H, m, 2CH2), νmax(KBr)/
cmϪ1 2900 (CH, aromatic), 1720 (C᎐O); m/z = 207 (Mϩ) (Calc.
᎐
for C10H9NO4: C, 58.0; H, 4.35. Found: C, 58.1; H, 4.36%).
p-Acetylphenyl cyclopropanecarboxylate. Mp 91–92 ЊC;
δH(400 MHz, CDCl3), 7.98 (2H, d, m-H, J 8.06), 7.20 (2H, d,
o-H, J 8.79), 2.60 (3H, s, CH3), 1.83–1.88 (1H, m, CH), 1.03–
1.21 (4H, m, 2CH2); νmax(KBr)/cmϪ1 2900 (CH, aromatic), 1720
(C᎐O); m/z = 204 (Mϩ) (Calc. for C H O : C, 70.6; H, 5.88.
᎐
12 12
3
Found: C, 70.7; H, 5.86%).
Rate constants
Rates were measured conductimetrically at 55.0 0.05 ЊC. The
conductivity bridge used in this work was a self-made computer
automatic A/D converter conductivity bridge. Pseudo-first-
order rate constants, kobs, were determined by the Guggenheim
method16 with a large excess of benzylamine; [phenyl cyclo-
propanecarboxylate] 1 × 10Ϫ3  and [benzylamine] = 0.030–
0.40 . Second-order rate constants, kN, were obtained from the
slope of a plot of kobs vs. benzylamine with more than five
concentrations of more than three runs and were reproducible
to within 3%.
5 F. M. Menger and J. H. Smith, J. Am. Chem. Soc., 1972, 94, 3824.
6 (a) D. J. Palling and W. P. Jencks, J. Am. Chem. Soc., 1984, 106,
4869; (b) M. Jedrzejczak, R. E. Motie, D. P. N. Satchell, R. S.
Satchell and W. N. Wassef, J. Chem. Soc., Perkin Trans. 2, 1994,
1471; (c) T. H. Kim, C. Hu, B.-S. Lee and I. Lee, J. Chem. Soc.,
Perkin Trans. 2, 1995, 2257; (d) K. H. Yew, H. J. Koh, H. W. Lee and
I. Lee, J. Chem. Soc., Perkin Trans. 2, 1995, 2263.
7 (a) I. Lee, Bull. Korean Chem. Soc., 1994, 15, 985; (b) D. Lee, C. K.
Kim and I. Lee, Bull. Korean Chem. Soc., 1995, 16, 1203; (c) I. Lee,
D. Lee and C. K. Kim, J. Phys. Chem. A, 1997, 101, 879.
8 (a) I. Lee, Chem. Soc. Rev., 1990, 19, 317; (b) I. Lee, Adv. Phys. Org.
Chem., 1992, 27, 57.
9 I. Lee, B.-S. Lee, H. J. Koh and B. D. Chang, Bull. Korean Chem.
Soc., 1995, 16, 277.
10 H. Neuvonen, J. Chem. Soc., Perkin Trans. 2, 1995, 951.
11 H. Neuvonen, J. Chem. Soc., Perkin Trans. 2, 1987, 159.
12 O. Exner, in Correlation Analysis in Chemistry, Recent Advances,
ed. N. B. Chapman and J. Shorter, Plenum Press, New York, 1978,
ch. 10.
13 (a) I. Lee, C. S. Shim, S. Y. Chung, H. Y. Kim and H. W. Lee,
J. Chem. Soc., Perkin Trans. 2, 1988, 1919; (b) M. R. F. Siggel,
A. Streitwieser Jr. and T. D. Thomas, J. Am. Chem. Soc., 1988, 110,
8022.
Product analysis
p-Nitrophenyl cyclopropanecarboxylate was reacted with
excess p-methylbenzylamine with stirring for more than 15 half-
lives at 55.0 ЊC in acetonitrile, and the products were isolated by
evaporating the solvent under reduced pressure. The product
mixture was separated by column chromatography (silica gel,
20% ethyl acetate–n-hexane). Analysis of the product gave the
following results.
Cyclopropyl-C(O)NHCH2C6H4-p-CH3. Mp 141–142 ЊC;
δH(400 MHz, CDCl3), 7.13–7.18 (4H, m, aromatic), 5.86
(1H, br s, NH), 4.40 (2H, s, CH2), 2.33 (3H, s, CH3), 1.65–1.69
(1H, m, CH), 0.73–1.32 (4H, m, 2CH3); νmax(KBr)/cmϪ1 3200
14 (a) A. Pross, Adv. Phys. Org. Chem., 1977, 14, 69; (b) O. Exner,
J. Chem. Soc., Perkin Trans. 2, 1993, 973.
(NH), 2900 (CH, aromatic), 1720 (C᎐O); m/z = 189 (Mϩ)
15 (a) E. A. Castro, F. Ibanez, M. Salas and J. G. Santos, J. Org. Chem.,
1991, 56, 4819; (b) B. D. Song and W. P. Jencks, J. Am. Chem. Soc.,
1989, 111, 8479.
᎐
(Calc. for C12H15NO: C, 76.2; H, 7.94. Found: C, 76.3; H,
7.95%).
16 E. A. Guggenheim, Phil. Mag., 1926, 2, 538.
Acknowledgements
We thank the Korea Science and Engineering Foundation, Inha
University and Chonju National University of Education for
support of this work.
Paper 8/01540F
Received 23rd February 1998
Accepted 17th March 1998
1332
J. Chem. Soc., Perkin Trans. 2, 1998