Oxyfunctionalization of aliphatic esters by methyl(trifluoromethyl)dioxirane

Article abstract of DOI:10.1021/jo9604189

The oxidation of lineal, cyclic, and bicyclic aliphatic p-chlorobenzoic and p-chorobenzenesulfonic acid esters 2 with methyl(trifluoromethyl)dioxirane (TFDO) (1) occurs at positions in the hydrocarbon chain distant from the directing group with a signific

Full text of DOI:10.1021/jo9604189

5564
J . Org. Chem. 1996, 61, 5564-5566
Oxyfu n ction a liza tion of Alip h a tic Ester s by
Meth yl(tr iflu or om eth yl)d ioxir a n e
Gregorio Asensio,* Gloria Castellano, Rossella Mello, and M. E. Gonza´lez Nu´n˜ez
Departamento de Quı´mica Orga´nica, Facultad de Farmacia, Universidad de Valencia,
Avda Vicente Andre´s Estelle´s s.n. E-46100-Burjassot, Valencia, Spain
Received February 29, 1996X
The oxidation of lineal, cyclic, and bicyclic aliphatic p-chlorobenzoic and p-chorobenzenesulfonic
acid esters 2 with methyl(trifluoromethyl)dioxirane (TFDO) (1) occurs at positions in the
hydrocarbon chain distant from the directing group with a significant degree of selectivity to give
the corresponding keto or hydroxy esters. Compounds 2 are relatively deactivated with respect to
this oxidation due to the electron-withdrawing nature of the ester moiety. Methylene CR-H and
Câ-H bonds remain unchanged in all cases, but tertiary Câ-H bonds undergo oxidation with TFDO
(1). Stereoelectronic factors are used to explain the faster reaction rate in competition experiments
for the oxidation of endo-norbornyl ester 2h than for its exo-isomer 2g.
In tr od u ction
Resu lts a n d Discu ssion
Initially, the oxidation of p-chlorobenzoic acid esters 2
was carried out with ketone-free dichloromethane solu-
tions of TFDO10 at -20 °C (see the Experimental Section),
to give readily isolable keto or hydroxy esters 3. Reac-
The selective oxyfunctionalization of hydrocarbons is
a major topic in current organic synthesis.1 Over the past
few years, several chemical methods have been developed
to achieve the oxidation of deactivated C-H bonds.2
These include the oxidation of hydrocarbons with transi-
tion metals using, for example, metalloporphyrins,3
ruthenium salts,4 and peroxometalates.5 Other methods
are based on metal-free oxidants, such as ozone,6 per-
fluoroalkyloxaziridines,7 or dioxiranes.8 These latter
compounds, especially methyl(trifluoromethyl)dioxirane
(1)9 (TFDO), are outstanding reagents for the oxidation
of C-H bonds of hydrocarbons due to their selectivity,
mild reaction conditions, and chemical yield. In our
continuing study of the factors that determine the
selectivity of dioxiranes in the oxyfunctionalization of
hydrocarbons, we report our results on the oxidation of
lineal, cyclic, and bicyclic aliphatic esters with TFDO (1),
which leads to the oxidation of distant positions in the
hydrocarbon chain with a significant degree of selectivity.
X Abstract published in Advance ACS Abstracts, J uly 15, 1996.
(1) Arndtsen, B. A.; Bergan, R. G.; Mobley, T. A.; Peterson, T. H.
Acc. Chem. Res. 1995, 28, 154.
(2) Reiser, O. Angew. Chem. 1994, 106, 73; Angew. Chem., Int. Ed.
Engl. 1994, 33, 69.
(3) Meunier, B. Chem. Rev. 1992, 92, 1411.
(4) (a) Tenaglia, A.; Terranova, E.; Waegell, B. Tetrahedron Lett.
1989, 30, 5271. (b) Carlsen, H. J . Synth. Commun. 1987, 17, 19.
(5) J aynes, B. S.; Hill, C. L. J . Am. Chem. Soc. 1995, 117, 4704.
(6) (a) Cohen, Z.; Keinan, E.; Mazur, Y.; Varkony, T. H. J . Org.
Chem. 1975, 40, 2141. (b) Cohen, Z.; Keinan, E.; Mazur, Y.; Ulman, A.
J . Org. Chem. 1976, 41, 2651. (c) Proksch, E.; de Meijere, A. Angew.
Chem. 1976, 88, 802; Angew. Chem., Int. Ed. Engl. 1976, 15, 761. (d)
Proksch, E.; de Meijere, A. Tetrahedron Lett. 1976, 4851.
(7) (a) DesMarteu, D. D.; Donadelli, A.; Montanari, V.; Petrov, V.
A.; Resnati, G. J . Am. Chem. Soc. 1993, 115, 4897. (b) Petrov, V. A.;
DesMarteau, D. D. J . Org. Chem. 1993, 58, 4754.
(8) (a) Curci, R.; Dinoi, A.; Rubino, M. F. Pure Appl. Chem. 1995,
67, 811. (b) Adam, W; Hadjiarapoglou, L. P. Topics in Current
Chemistry; Springer-Verlag: Berlin, 1993; Vol. 164, p 45. (c) Adam,
W; Hadjiarapoglou; Curci, R.; Mello, R. Organic Peroxides; Wiley: New
York, 1992; Chapter 4. (d) Curci, R. Advances in Oxygenated Processes;
J AI: Greenwich, CT, 1990; Vol. 2, Chapter 1. (e) Murray, R. W. Chem.
Rev. 1989, 89, 1187. (f) Adam, W.; Curci, R.; Edwards, J . O. Acc. Chem.
Res. 1989, 22, 205.
(9) (a) Asensio, G.; Mello, R.; Gonza´lez-Nu´n˜ez, M. E.; Castellano,
G.; Corral, J . Angew. Chem., Int. Ed. Engl. 1996, 35, 217. (b) Asensio,
G.; Gonza´lez-Nu´n˜ez, M. E.; Mello, R.; Boix-Bernardini, C.; Adam, W.
J . Am. Chem. Soc. 1993, 115, 7250. (c) Adam, W.; Asensio, G.; Curci,
R.; Gonza´lez-Nu´n˜ez, M. E.; Mello, R. J . Org. Chem. 1992, 57, 953. (d)
Mello, R.; Cassidei, L.; Fiorentino, M.; Fusco, C.; Curci, R. Tetrahedron
Lett. 1990, 31, 3067. (e) Mello, R.; Fiorentino, M.; Fusco, C.; Curci, R.
J . Am. Chem. Soc. 1989, 111, 6749.
tions were monitored by iodometric titration11 to control
the consumption of TFDO (1). In general, the conversion
(10) Adam, A.; Curci, R.; Gonza´lez-Nu´n˜ez, M. E.; Mello, R. J . Am.
Chem. Soc. 1991, 113, 7654.
(11) Adam, W.; Asensio, G.; Curci, R.; Gonza´lez-Nu´n˜ez, M. E.; Mello,
R. J . Am. Chem. Soc. 1992, 114, 8345.
S0022-3263(96)00418-5 CCC: $12.00 © 1996 American Chemical Society

Oxyfunctionalization of Aliphatic Esters
J . Org. Chem., Vol. 61, No. 16, 1996 5565
Ta ble 1. Oxid a tion of Ester s 2 w ith TF DO (1)a
Methylene groups are converted directly into ketones
by TFDO. However, it has been shown9a,e that this
reaction occurs in two steps through the corresponding
secondary alcohol, which undergoes further oxidation at
CR-H faster than any other C-H bond can react. In fact,
we recently showed that the monohydroxylation of
hydrocarbons9a can be achieved with TFDO in excellent
yields when the oxidation is performed in the presence
of an excess of trifluoroacetic anhydride to trap the
hydroxy group as trifluoroacetic acid monoester, which
does not to undergo further oxidation in the presence of
unreacted hydrocarbon. On the other hand, in the
reaction of norbornane with TFDO, exo-C-H bonds are
hydroxylated much faster than their endo counterparts.9a,e
To determine the relationship between oxidation rate,
selectivity, and efficacy in the transmission of the electron-
withdrawing effect from the ester moiety along C-C and
C-H bonds, we carried out the competitive oxidation of
an equimolar mixture of exo- and endo-norbonyl p-
chlorobenzoates 2g and 2h with TFDO (1) in a molar
ratio of 1:1:2 in dichloromethane at -20 °C. Under these
conditions, we found that kendo/kexo ) 1.6 ( 0.05, which
indicates that the C(6)- and C(5)-Hexo bonds of the exo-
ester 2g are more deactivated with respect to electrophilic
attack by TFDO than the corresponding C(6)- and C(5)-
product distribution 3a -jc (%)c
entry
2b
â
γ
δ
ꢀ
1
2
3
4
5
6
7
8
9
a
b
c
d
e
f
g
h
if
j
>98
12d
14d
88 (80)
29 (25)
92 (90)
60 (56)
85 (83)
98 (95)
91 (90)
57 (55)
8d
40d
15 (9)
2e
9 (5)
>98 (97)
30 (25)
10
70 (68)
a
Reactions were carried out at -20 °C in CH2Cl2 for 48 h with
b
an initial molar ratio 2:1 ) 3. Substrate conversion was 100%
in all the cases. c From GC or NMR analysis of the crude reaction
d
mixture; isolated yields are in parentheses. Decomposes in the
isolation process. e Not isolated. f Used as acetate.
of dioxirane was complete after 48 h. Compounds 3 were
isolated by column chromatography and analyzed by GC,
1
GC-MS, and H- and 13C-NMR. The results are shown
in Table 1. Oxidations were also carried out with acetic,
trifluoroacetic, and p-toluensulfonic acid esters without
noticeable changes in selectivity. Slower oxidation rates
were found for trifluoroacetic and p-chlorobenzenesulfon-
ic acid esters, as expected from the stronger electron-
withdrawing ability of the ester moiety in these cases.
We should note that the aromatic rings of p-chlorobenzoic
and p-chorobenzenesulfonic acid esters were stable in all
cases against oxidation by 1, although the reaction times
were longer and the temperatures were higher than in
other TFDO oxidations.
H
exo bonds in the endo-ester 2h . This suggests that there
is a different level of deactivating hyperconjugative
interaction between the ester moiety and the C-Hexo
bonds in compounds 2g and 2h , most likely due to the
different (exo or endo) orientation of the ester in each
diastereomer. Since the hyperconjugative interaction12
is transmitted by overlap of σ bonding orbitals of the
cyclic framework with the antibonding σ* orbital of the
C(2)-O bond, the orbital interaction will be greater in
the exo-ester 2g than in the endo-isomer 2h . This is
consistent with the faster reaction rate observed for the
oxidation of the endo-ester 2h than for 2g in the competi-
tion experiment. However, this effect is not accompanied
by any significant increase in the regioselectivity in the
oxidation (Table 1, entries 7 and 8). Notably, we found
comparable regioselectivities in the oxidation of trifluo-
roacetic and arenesulfonic acid esters regardless of the
stronger electron-withdrawing character of the ester
group in these cases.
It is widely accepted that the oxidation of C-H bonds
by TFDO (1) is an electrophilic process.8 Consequently,
compounds 2 are relatively deactivated with regard to
this oxidation due to the electron-withdrawing nature of
the ester moiety. The reactivity of the methylene groups
in 2 increases with the distance to the ester function, as
expected from the inductive nature of the directing effect.
The observed product distribution reflects that the effect
of the ester group is weakened with the distance along
the aliphatic chain. Oxidation occurs preferentially at
distant positions in the chain. Methylene CR-H and
Câ-H bonds remain unchanged in all cases (Table 1). In
contrast, the tertiary Câ-H bond in compound 2j is
oxidized by TFDO (1) due to the preference shown by
TFDO for the oxidation of tertiary hydrogens, which is
well documented in simple hydrocarbons.8,9e Under the
influence of the ester group, the reactivities of tertiary
Hâ and secondary Hγ hydrogens are similar, and conse-
quently, the oxidation of compound 2j gives a mixture of
the hydroxy ester 3jâ and the keto ester 3jγ (Table 1,
entry 10). When two tertiary C-H bonds are present,
as in compound 2i, the oxidation is selective and occurs
at the less-deactivated hydrogen position to exclusively
give the hydroxy ester 3iγ. Methyl groups are not
oxidized in any case due to their low reactivity.8,9e â-Keto
esters 3bγ, 3cγ, 3d γ, and 3eγ were identified in the crude
reaction mixture by GC-MS and 1H- and 13C-NMR
(Table 1). However, attempts to isolate these compounds
by column chromatography were unsuccessful, probably
due to the loss of carboxylic acid and subsequent polym-
erization of the resulting R,â-unsaturated carbonyl com-
pound under our experimental conditions. A similar
â-elimination process occurs in these keto esters when
the crude reaction mixture is allowed to stand at room
temperature for 24 h.
Con clu sion s
These results suggest that esterification is an efficient
method for protecting primary and secondary aliphatic
alcohols against oxidation by methyl(trifluoromethyl)-
dioxirane (1) in the presence of hydrocarbons. While
aliphatic esters are oxidized by 1, oxidation occurs more
slowly than with hydrocarbons due to the electron-
withdrawing nature of the ester group. This oxidation
occurs regioselectively at positions in the chain distant
from the directing group. In this way, esters 2 are
regioselectively converted into the corresponding keto
esters or hydroxy esters 3 in good yields.
Exp er im en ta l Section
Gen er a l Asp ects. GLC analyses were performed on a
DB-1 capillary column (25 m, film thickness 1 µm, i.d. 0.25
mm), and GC-MS measurements were made on a PBX-5
capillary column (30 m, film thickness 1 µm, i.d. 0.23 mm).
(12) Lowry T. H.; Richardson, K. S. Mechanism and Theory in
Organic Chemistry; HarperCollins Publishers: New York, 1987.

5566 J . Org. Chem., Vol. 61, No. 16, 1996
Asensio et al.
All solvents were purified by standard procedures and freshly
distilled prior to use. Methyl(trifluoromethyl)dioxirane (1) in
trifluoroacetone and ketone-free solutions of 1 in methylene
chloride were obtained as reported9e,10 starting from caroate
and trifluoroacetone at pH ca. 7.5.
4-[(p-Ch lor oben zoyl)oxy]cycloh eptan on e (3fδ). 1H NMR
(CDCl3, 250 MHz): δ 2.06 (m, 6H), 2.65 (m, 4H), 5.28 (m, 1H),
7.42 (d, J ) 8.6 Hz, 2H), 7.96 (d, J ) 8.6 Hz, 2H. 13C NMR
(CDCl3, 62.8 MHz): δ 19.0, 28.7, 34.8, 37.7, 43.4, 73.8, 128.7,
130.9, 139.5, 164.7, 213.3. MS (EI, 70 eV): m/ z 266 (0.2), 141
Oxid a t ion of Alk yl p -Ch lor ob en zoa t es (2). Gen er a l
P r oced u r e. To a stirred solution of cyclohexyl p-chloroben-
zoate (2e) (0.29 mmol, 70 mg) in dichloromethane at -20 °C
was added a 0.4 M dichloromethane solution of TFDO (initial
molar ratio 1:3) in one batch, and the mixture was allowed to
stand at -20 °C for 48 h. The reaction mixture was analyzed
by GC and GC-MS. The volatiles were removed under
vacuum at 0 °C, and the residue was dissolved in CDCl3 and
analyzed by NMR. Column chromatography (silica gel, n-
hexane:dichloromethane 1:1) of the crude yielded 41.1 mg of
4-[(p-chlorobenzoyl)oxy]cyclohexanone (3eδ) (56%). The minor
product 3-[(p-chlorobenzoyl)oxy]cyclohexanone (3eγ) decom-
posed during elution.
(42.0), 139 (100.0), 111 (53.3). Exact mass: calcd for C14H15
ClO3 266.0710, found 266.0709.
-
exo-2-[(p-Ch lor oben zoyl)oxy]n or bor n a n -6-on e (3gγ).
1H NMR (CDCl3, 250 MHz): δ 1.84 (m, 3H), 2.07 (m, 3H), 2.84
(m, 2H), 5.06 (m, 1H), 7.35 (d, J ) 8.4 Hz, 2H), 7.88 (d, J )
8.7 Hz, 2H). 13C NMR (CDCl3, 62.8 MHz): δ 3.0, 36.1, 38.7,
44.7, 56.8, 72.7, 128.4, 128.7, 130.3, 139.6, 164.8, 219.4. MS
(EI, 70 eV): m/ z 238 (13. 3), 236 (41.0), 141 (28.4), 138 (100.0).
Exact mass: calcd for C14H13ClO3 264.0553, found 264.0548.
exo-2-[(p -Ch lor oben zoyl)oxy]n or bor n a n -5-on e (3gδ).
1H NMR (CDCl3, 250 MHz): δ 1.97 (m, 6H), 2.63 (d, J ) 4.8
Hz, 1H), 2.84 (d, J ) 4.8 Hz, 1H), 5.05 (d, J ) 6.8 Hz, 1H),
7.39 (d, J ) 8.6 Hz, 2H), 7.92 (d, J ) 8.6 Hz, 2H). 13C NMR
(CDCl3, 62.8 MHz): δ 33.4, 34.4, 39.8, 40.7, 48.7, 75.6, 128.4,
128.7, 130.9, 139.5, 165.1, 215.0. MS (EI, 70 eV): m/ z 266
(1.2), 264 (3.7), 139 (100.0), 108 (26.4). Exact mass: calcd for
C14H13ClO3 264.0553, found 264.0559.
en d o-2-[(p-Ch lor oben zoyl)oxy]n or bor n a n -6-on e (3h γ).
The compound was identified by GC-MS in the crude reaction
mixture. MS (EI, 70 eV): m/ z 266 (0.7), 267 (1.6), 141 (33.5),
139 (100.0), 111(29.2). Exact mass: calcd for C14H13ClO3
264.0553, found 264.0545.
en d o-2-[(p-Ch lor oben zoyl)oxy]n or bor n a n -5-on e (3h δ).
1H NMR (CDCl3, 250 MHz): δ 1.55 (m, 1H), 1.85 (m, 2H), 2.15
(m, 1H), 2.52 (m, 2H), 2.67 (m, 1H), 3.07 (m, 1H), 5.44 (m,
1H), 7.43 (d, J ) 8.6 Hz, 2H), 7.95 (d, J ) 8.6 Hz, 2H). 13C
NMR (CDCl3, 62.8 MHz): δ 33.1, 36.1, 38.2, 39.3, 49.9, 73.9,
128.1, 128.8, 130.9, 139.7, 165.4, 215.9. MS (EI, 70 eV): m/ z
266 (2.7), 264 (7.2), 141 (28.8), 139 (100.0). Exact mass: calcd
for C14H13ClO3 264.0553, found 264.0553.
4-[(p-Ch lor oben zoyl)oxy]-2-bu ta n on e (3a γ). 1H NMR
(CDCl3, 250 MHz): δ 2.18 (s, 3H), 2.86 (t, J ) 6.2 Hz, 2H),
4.53 (t, J ) 6.2 Hz, 2H), 7.34 (d, J ) 8.6 Hz, 2H), 7.88 (d, J )
8.6 Hz, 2H). 13C NMR (CDCl3, 62.8 MHz): δ 30.6, 42.2, 59.9,
128.2, 128.7, 130.9, 130.9, 139.5, 165.9, 205.9. MS (EI, 70
eV): m/ z 228 (3.7), 226 (11.5), 158 (39.3), 156 (100), 141 (59.4),
139 (36.8), 111 (50.5), 75 (27.4). Exact mass: calcd for C11H11
ClO3 226.0397, found 226.0391.
-
5-[(p-Ch lor oben zoyl)oxy]-2-p en ta n on e (3bδ). 1H NMR
(CDCl3, 250 MHz): δ 2.00 (m, 2H), 2.12 (s, 3H), 2.55 (t, J )
7.2 Hz, 2H), 4.27 (t, J ) 6.4 Hz, 2H), 7.36 (d, J ) 8.6 Hz, 2H),
7.90 (d, J ) 7.6 Hz, 2H). 13C NMR (CDCl3, 62.8 MHz): δ 22.8,
30.0, 39.9, 64.4, 128.6, 128.7, 130.9, 139.4, 165.7, 207.5. MS
(EI, 70 eV): m/ z 242 (0.3), 240 (0.5), 183 (31.0), 158 (30.6),
141 (100), 140 (30.7), 139 (65.9), 113 (30.0), 111 (81.7), 101
(89.3), 84 (96.7), 75 (38.1). Exact mass: calcd for C12H13ClO3
240.0553, found 240.0541.
6-[(p-Ch lor oben zoyl)oxy]-3-h exa n on e (3cδ). 1H NMR
(CDCl3, 250 MHz): δ 0.99 (t, J ) 7.3 Hz, 3H), 2.00 (m, 2H),
2.38 (q, J ) 7.3 Hz, 2H), 2.50 (t, J ) 7.3 Hz, 2H), 4.25 (t, J )
6.4 Hz, 2H), 7.34 (d, J ) 8.6 Hz, 2H), 7.89 (d, J ) 8.6 Hz, 2H).
13C NMR (CDCl3, 62.8 MHz): δ 7.8, 22.8, 36.1, 38.5, 53.4, 64.5,
128.6, 128.7, 130.9, 139.4, 165.7, 210.3. MS (EI, 70 eV): m/ z
158 (11.8), 157 (19.7), 156 (35.5), 141 (50.5), 139 (100), 111
(42.9), 98 (33.2). Exact mass: calcd for C13H16ClO3 255.0788,
found 255.0783.
1-Acetoxy-cis-10-d eca lol (3iγ). 1H NMR (CDCl3, 250
MHz): δ 1.40 (m, 15H), 2.03 (s, 3H), 5.31 (m, 1H). 13C NMR
(CDCl3, 62.8 MHz): δ 19.4, 21.3, 22.4, 23.7, 25.2, 25.3, 29.7,
41.8, 46.3, 53.4, 72.5, 73.5, 170.8. MS (EI, 70 eV): m/ z 153
(14.8), 152 (89.5), 134 (56.1), 124 (66.7), 123 (37.1), 110 (46.8),
109 (38.0), 95 (35.7), 55 (40.9), 43 (100.0), 41 (32.9). Exact
mass: calcd for C12H20O3Na (M+ + Na) 235.1310, found
235.1312.
1-[(p-Ch lor oben zoyl)oxy]-2-m eth yl-2-bu ta n ol (3jâ). 1H
NMR (CDCl3, 250 MHz): δ 0.98 (t, J ) 7.5 Hz, 3H), 1.27 (s,
3H), 1.66 (q, J ) 7.6 Hz, 2H), 4.22 (s, 2H), 7.44 (d, J ) 8.7 Hz,
2H), 7.98 (d, J ) 8.6 Hz, 2H). 13C NMR (CDCl3, 62.8 MHz):
δ 7.9, 23.4, 31.7, 71.3, 72.1, 128.3, 128.8, 131.0, 139.6, 165.7.
MS (EI, 70 eV): m/ z 213 (2.6), 139 (62.1), 73 (100.0. Exact
mass: calcd for C13H16ClO3 255.0788, found 255.0785.
4-[(p-Ch lor oben zoyl)oxy]-3-m eth yl-2-bu ta n on e (3jγ).
1H NMR (CDCl3, 250 MHz): δ 1.23 (d, J ) 7.2 Hz, 3H), 2.25
(s, 3H), 3.02 (m, J ) 7.1 Hz, 1H), 4.44 (m, 2H), 7.40 (d, J )
8.6 Hz, 2H), 7.93 (d, J ) 8.6 Hz, 2H). 13C NMR (CDCl3, 62.8
MHz): δ 13.4, 28.7, 46.0, 65.9, 128.2, 128.8, 130.9, 165.4, 209.3.
MS (EI, 70 eV): m/ z 199 (11.3), 156 (38.2), 141 (35.7), 139
6-[(p-Ch lor oben zoyl)oxy]-2-h exa n on e (3cE). 1H NMR
(CDCl3, 250 MHz): δ 1.75 (m, 4H), 2.16 (s, 3H), 2.52 (t, J )
6.7 Hz, 2H), 4.32 (t, J ) 6.0 Hz, 2H), 7.41 (d, J ) 8.6 Hz, 2H),
7.97 (d, J ) 8.6 Hz, 2H). 13C NMR (CDCl3, 62.8 MHz): δ 20.1,
28.1, 29.9, 42.9, 64.8, 128.7, 130.9, 139.3, 165.7, 208.4. MS
(EI, 70 eV): m/ z 158 (17.1), 157 (27.1), 156 (49.5), 141 (74.8),
141 (52.3), 111 (57.8), 98 (100), 75 (27.9). Exact mass: calcd
for C13H16ClO3 255.0788, found 255.0782.
5-[(p-Ch lor oben zoyl)oxy]-2-h exa n on e (3d δ). 1H NMR
(CDCl3, 250 MHz): δ 1.36 (d, J ) 6.2 Hz, 3H), 1.97 (q, J ) 7.1
Hz, 2H), 2.14 (s, 3H), 2.54 (t, J ) 7.4 Hz, 2H), 5.16 (m, J ) 6.3
Hz, 1H), 7.39 (d, J ) 8.6 Hz, 2H), 7.95 (d, J ) 8.6 Hz, 2H). 13
C
NMR (CDCl3, 62.8 MHz): δ 20.1, 29.7, 30.0, 39.5, 71.2, 128.6,
128.8, 130.9, 139.3, 165.2, 207.7. MS (EI, 70 eV): m/ z 157
(5.3), 156 (5.4), 141 (32.3), 139 (100), 115 (31.0), 98 (26.4). Exact
mass: calcd for C13H16ClO3 255.0788, found 255.0784.
4-[(p-Ch lor oben zoyl)oxy]cycloh exan on e (3eδ). 1H NMR
(CDCl3, 250 MHz): δ 2.06 (m, 4H), 2.48 (m, 2H), 2.60 (m, 2H),
5.42 (m, 1H), 7.45 (d, J ) 8.6 Hz, 2H), 8.00 (d, J ) 8.5 Hz,
2H). 13C NMR (CDCl3, 62.8 MHz): δ 30.5, 37.3, 69.4, 128.8,
130.9, 139.7, 164.9, 209.7. MS (EI, 70 eV): m/ z 156 (4.0), 141
(33.8), 139 (100.0), 111 (25.0), 96 (57.9). Exact mass: calcd
for C13H14ClO3 253.0631, found 253.0640.
(100.0), 111 (25.7), 43 (82.5). Exact mass: calcd for C13H16
ClO3 255.0788, found 255.0780.
-
Ack n ow led gm en t. This work was supported by the
Spanish Direccio´n General de Investigacio´n Cient´ıfica
y Te´cnica (PB93-0681). We thank the S. C. S. I. E.
(Universidad de Valencia) for the use of NMR and GC-
MS facilities.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of compounds 3a γ, 3bδ, 3cδ, 3cꢀ, 3d δ, 3eδ, 3fγ, 3fδ,
3gγ, 3gδ, 3h δ, 3iγ, 3jâ, and 3jγ (28 pages). This material is
contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
3-[(p-Ch lor oben zoyl)oxy]cycloh eptan on e (3fγ). 1H NMR
(CDCl3, 250 MHz): δ 2.00 (m, 6H), 2.58 (m, 2H), 2.94 (m, 2H),
5.40 (m, 1H), 7.41 (d, J ) 8.5 Hz, 2H), 7.93 (d, J ) 8.6 Hz,
2H). 13C NMR (CDCl3, 62.8 MHz): δ 23.8, 24.8, 35.1, 44.4,
48.3, 70.1, 128.5, 128.7, 130.9, 139.6, 164.6, 210.2. MS (EI,
70 eV): m/ z 266 (0.4), 141 (33.5), 139 (100.0). Exact mass:
calcd for C14H15ClO3 266.0710, found 266.0701.
J O9604189