Synthesis and glutathione S-transferase structure-affinity relationships of nonpeptide and peptidase-stable glutathione analogues

Article abstract of DOI:10.1021/jm970518m

A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple carbon-carbon bonds or isosteric E double bonds were prepared. The optimal length for the two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-affinity relationships. Affinities of the analogues 14a-f, 23, and 25 were evaluated for a recombinant GST enzyme using a new affinity chromatography method previously developed in our laboratory. Analysis of these analogues gives an additional understanding for GST affinity requirements: (a) the carbon skeleton must conserve that of glutathione since analogue 14a showed the best affinity (IC₅₀ = 5.2 μM); (b) the GST G site is not able to accommodate a chain length elongation of one methylene group (no affinity for analogues 14c,f); (c) a one-methylene group chain length reduction is tolerated, much more for the 'Glu side' (14d, IC₅₀ = 10.1 μM) than for the 'Gly side' (14b, IC₅₀ = 1800 μM); (d) the mercaptomethyl group must remain at position 5 as shown from the null affinity of the 6-mercaptomethyl analogue 14e; (e) the additional peptide isosteric E double bond (25) or hydroxyl derivative (23) in 14e did not help to retrieve affinity. This work reveals useful information for the design of new selective nonpeptidic and peptidase-stable glutathione analogues.

Full text of DOI:10.1021/jm970518m

2278
J . Med. Chem. 1998, 41, 2278-2288
Syn th esis a n d Glu ta th ion e S-Tr a n sfer a se Str u ctu r e-Affin ity Rela tion sh ip s of
Non p ep tid e a n d P ep tid a se-Sta ble Glu ta th ion e An a logu es
Philippe Klotz,* Amal Slaoui-Hasnaoui,† J ean-Louis Bane`res, J ean-Fre´de´ric Duckert, and J ean-Claude Rossi*
Laboratoire de Chimie Biomole´culaire et Interactions Biologiques, UPRESA CNRS 5074, Universite´ de Montpellier I,
Faculte´ de Pharmacie, 15, Av. Charles Flahault, 34060 Montpellier Cedex 2, France
Abdelali Kerbal
Laboratoire de Chimie Organique, Universite´ Sidi Mohamed Ben Abdellah, Faculte´ des Sciences Dhar Mahrez BP1796,
Atlas Fe`s, Maroc
Received August 4, 1997
A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple
carbon-carbon bonds or isosteric E double bonds were prepared. The optimal length for the
two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-
affinity relationships. Affinities of the analogues 14a -f, 23, and 25 were evaluated for a
recombinant GST enzyme using a new affinity chromatography method previously developed
in our laboratory. Analysis of these analogues gives an additional understanding for GST
affinity requirements: (a) the carbon skeleton must conserve that of glutathione since analogue
14a showed the best affinity (IC50 ) 5.2 µM); (b) the GST G site is not able to accommodate a
chain length elongation of one methylene group (no affinity for analogues 14c,f); (c) a one-
methylene group chain length reduction is tolerated, much more for the “Glu side” (14d , IC50
) 10.1 µM) than for the “Gly side” (14b, IC50 ) 1800 µM); (d) the mercaptomethyl group must
remain at position 5 as shown from the null affinity of the 6-mercaptomethyl analogue 14e;
(e) the additional peptide isosteric E double bond (25) or hydroxyl derivative (23) in 14e did
not help to retrieve affinity. This work reveals useful information for the design of new selective
nonpeptidic and peptidase-stable glutathione analogues.
In tr od u ction
Glutathione (GSH) is an important natural tripeptide
(γ-Glu-Cys-Gly) with multifunctional properties.1-3 Its
implication in detoxification, oxidation and radiation
protection, cancer genesis, and immune phenomena
increased the general interest in GSH research over the
last several years. Although a great number of peptidic
GSH analogues have been synthesized,4-7 to our knowl-
edge, nonpeptidic GSH analogues of type 1 are unknown
in the literature. We replaced the two sensitive peptide
bonds of the glutathione moiety by simple carbon-
carbon bonds or E olefinic double bonds. In the latter
case the olefinic linkage is bioisosteric with the amide
bond,8 as was previously reported for the leukotriene
(LT) D4 series.9,10
Adang et al.11 gave some important structural re-
quirements concerning the design of peptidic GSH
analogues having glutathione S-transferase (GST) en-
zyme activity. On this basis and considering our
analogues of type 1 (Figure 1), we kept the two car-
boxylic acid groups of GSH intact and deleted the
γ-glutamyl amino group. To further determine the
structural requirements for the best GSH mimic, we
first wanted to identify the optimal length for the two
* To whom correspondence should be addressed. J .-C.R.: e-mail,
F igu r e 1. Retrosynthesis of mercaptomethyl diacids 1.
rossi@pharma.univ-montp1.fr. P.K.: address, Laboratoire de Pharma-
cochimie Mole´culaire, Faculte´ de Pharmacie 74, Route du Rhin, BP24,
67401 Illkirch Cedex, France; e-mail: Ph.Klotz@pharma.u-strasbg.fr.
alkyl chains on either side of the mercaptomethyl group
in 1. Therefore, we initiated a structure-affinity invest-
igation of a series of synthetic saturated derivatives of
† Present address: Laboratoire de Chimie Organique, Universite´
Sidi Mohamed Ben Abdellah, Faculte´ des Sciences Dhar Mahrez
BP1796, Atlas Fe`s, Maroc.
S0022-2623(97)00518-9 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/30/1998

Nonpeptidic and Peptidase-Stable GSH Analogues
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13 2279
were performed with freshly prepared enamines 5
and 6, by known methods.17 The diacids 10a -e were
then easily esterified with methanol in the presence of
DCC and DMAP, to afford the dimethyl esters 11a -e
in good to excellent yields (80-95%). Methyl ethyl
diester 11f was prepared differently as explained
below. Transformation of the ketonic group of com-
pounds 11a -f into a methylene double bond was
completed by treatment with methylenetriphenylphos-
phorane in 75%-85% yields.18 Double-bond function-
alization of 12a -f was then performed by reaction with
thiolacetic acid under free-radical conditions. This
reaction is usually initiated with light irradiation,19 but
for easier large-scale preparation, we modified the
protocol and replaced the light radical initiation by
AIBN. The thiolacetates 13a -f were obtained from
exclusive anti-Markovnikov addition. They were dif-
ficult to purify, and several silica gel column chromato-
graphies were necessary for correct elemental analysis.
Subsequent treatment of 13a -f with KOH in a water-
ethanol mixture afforded, after acidification, the mer-
capto diacids 14a -f in good yields (59-85%). Reaction
at 90 °C for only 30 min produced exclusively the thiols
14a -f (on TLC analysis), whereas longer reaction times
(>2 h) led to mixtures containing the oxidized dithio
compounds of 14a -f. Reactions were therefore per-
formed under argon, and final mercapto derivatives
14a -f were protected against oxygen. Total functional
identification between reduced thiols and their oxidized
dithio forms was possible with the synthesis of the
oxidized dithio compound of 14a . This was performed
by oxidation of 14a with iodine in aqueous methanol
containing NaOH. The structure of 14a was established
by comparison with the prepared dithio compound using
1H and 13C NMR. This synthetic route is attractive
because it is short, the overall yields are good (around
25%), and the starting materials are commercially
available and inexpensive. Depending on the starting
enamine and acid chloride, a great number of chain
length variations can be obtained.
analogue concentration (Log, µM)
F igu r e 2. Affinity curves of the GSH analogues. Inhibition
of specific binding of GST to glutathione-agarose by GSH and
14a ,b,d . The dissociation assays were carried out as described
in the Experimental Section. Each data point is the mean (
standard deviation of three experiments.
type 1. Second, we introduced selective E double bonds
in order to evaluate the affinity improvement in terms
of amide bond isosterics. We used a GST enzyme
binding experiment as a good way to determine if the
analogues of type 1 were actual GSH mimics. We
evaluated their affinity with a recombinant GST en-
zyme, very similar to the mammalian µ class GST. We
used a new binding experiment developed in our labora-
tory based on an affinity chromatocolumn12 using GSH
as reference (Figure 2).
Herein we describe the synthesis and the biological
evaluation of the first and original nonpeptidic glu-
tathione analogues as mercapto derivatives 1 and
discuss their structure-affinity relationships for the
GST enzyme. The final target of our project, after
linkage between LTA4 and nonpeptidic GSH analogues,
is the synthesis of LTC4 stable analogues against
enzymatic metabolism. These compouds would there-
fore be a powerful tool in the characterization of the
human LTC4 receptor (Cys-LT2 receptors13-15), which
constitutes a main preoccupation in our laboratory.
For the requisite mercapto diacid 14f, the correspond-
ing keto diester 11f cannot be synthesized through the
Stork enamine acylation. To overcome this limitation,
we used another strategy for the preparation of 11f as
outlined in Scheme 2. Ethyl 7-iodoheptanoate (16) was
first prepared from its commercially available bromide
derivative 15. The iodide 16 was then converted to the
corresponding zinc iodide organometallic, with the zinc-
copper couple, and reacted with acid chloride 8 in a
palladium(0) coupling reaction inspired from Tamaru
et al.20 In this way, we obtained the keto diester 11f in
high yield (80%). Compound 11f was further function-
alized as described above in Scheme 1.
Ch em istr y
We wanted to develop a synthetic strategy that could
be used for the synthesis of either saturated or unsatur-
ated compounds of type 1. Thus, as shown in Figure 1,
we planned the preparation of mercaptomethyl diacids
1 from the functionalization of the ethylene derivatives
2. These latter compounds were derived from the
ketones 3 via carbonyl homologation. Ketones of type
3 with conjugated double bonds were prepared from the
selective dehydrohalogenation reaction of the R,R′-
dihalogenated protected ketones 4.
Following this strategy, we prepared the saturated
analogues 14a -f in a synthesis depicted in Scheme 1.
A Stork16 condensation between enamine 5 or 6 and
commercially available acid chlorides 7-9 gave us, after
alkaline treatment, the keto diacids 10a -e. Reactions
We then prepared compounds 23 and 25 containing
exclusively E double bonds derived from symmetrical
keto diester 11e as depicted in Scheme 3. For clean
bromination-dehydrobromination reactions, ketone 11e
was first converted to its ethylene ketal 17 using
classical methods.21 Monobromination of 17 was carried
out with slow addition of bromine (1 equiv) in ethyl
ether at room temperature. Monobrominated ethylene
ketal 18 was obtained in high yield (90%). Dehydro-
bromination was optimal when using DBU in warm
DMSO. These conditions produced clean dehydrohalo-

2280 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13
Klotz et al.
Sch em e 1. Synthesis of Saturated Mercaptomethyl Diacids 14a -fa
a
Legend: (a) (1) CH2Cl2, Et3N, reflux, (2) HCl (18%), reflux; (b) (1) KOH, 100 °C, (2) HCl (concd); (c) DCC, DMAP, MeOH, CH2Cl2; (d)
t-BuOK, Ph3PCH3Br, THF; (e) CH3COSH, AIBN, 90 °C; (f) (1) KOH, ethanol/water, reflux, (2) HCl. *For the synthesis of compound 11f,
see Scheme 2.
Sch em e 2. Synthesis of Compound 11fa
refrigerated and protected against oxygen to avoid
oxidation.
Following our synthetic strategy (Figure 1), we also
attempted to prepare the analogues 1 containing two E
double bonds. Starting from ketones 11a -e, we syn-
thesized the dibromo ethylene ketals 4 (Figure 1) by
regioselective dibromination. Subsequent bis-dehydro-
bromination and deprotection of the ethylene ketal gave
the cross-conjugated dienones 3. Again, the generated
double bonds were exclusively in the E form (1H NMR,
360 MHz: J trans g 15 Hz). These unsaturated ketones
3 were shown to be metastable compounds. They are
known to undergo Michael type additions and Nazarov
cyclizations. However, Wittig olefination gave us the
cross-conjugated trienes 2 without isomerization of the
E double bonds (on NMR analysis). We then attempted
the regioselective functionalization of the ethylene
terminal double bond in order to obtain the bis-homoal-
lylic thiols 1, but all attempts failed in our hands. The
cross-conjugated trienes 2 were very sensitive com-
pounds and extremely difficult to handle. Isomerization
and polymerization were the predominant reactions. We
want to stress that E,E-cross-conjugated trienes of type
2 have not been previously described in the literature.
Recently, the synthesis of a reasonably stable Z,Z-cross-
conjugated triene was reported.24 However this result
is apparently not transposable to the E,E system, as
shown by our results. No chemical method is available
for the selective and specific formation of (E,E)-1,4-
dienes as in thiols of type 1. One of our challenges was
to introduce a new approach to this synthetic problem
through the synthesis of 1,4-dienes. We are currently
studying other synthetic strategies for the formation of
(E,E)-1,4-dienes.
a
Legend: (a) NaI, acetone, reflux, 87%; (b) Zn(Cu), (Ph3P)4Pd(0),
benzene/DMA, 80%.
genation with exclusive formation of the E double-bond
isomer 19 (1H NMR: J trans ) 15.5 Hz) in good yield
(86%). Deprotection of the ethylene ketal with TFA,
water, and silica gel afforded the R,â-unsaturated
ketone 20. Wittig functionalization with methylene-
triphenylphosphorane then gave the diene 21. Regi-
oselective reaction of the terminal double bond could not
be achieved with thiolacetic acid as for the saturated
series (Scheme 1). This reaction was realized through
a selective hydroboration step using 9-BBN-H.22 After
oxidative cleavage, we isolated the homoallylic alcohol
22, which was saponified with KOH to the final diacid
alcohol 23. The conversion of the alcohol function to
thiol 25 was achieved using the Mitsunobu reaction.23
The thiolacetate 24 was first prepared and obtained in
high yield (93%) but required tedious purification.
Saponification and acetyl cleavage with KOH gave the
desired homoallylic thiol 25. The product was kept
Bioch em istr y
A protein affinity chromatography method12 was used
to evaluate the binding of the glutathione analogues to
the recombinant Schistosoma japonicum GST protein.
The recombinant GST was bound to a glutathione-
agarose slurry for 2 h at room temperature in a PBS
buffer. The glutathione analogue was then added at
increasing concentrations. After a 2 h incubation, the

Nonpeptidic and Peptidase-Stable GSH Analogues
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13 2281
Sch em e 3. Synthesis of Unsaturated Mercaptomethyl Diacids 23 and 25a
a
Legend: (a) ethylene glycol, p-toluenesulfonic acid, benzene, Dean-Stark, 75%; (b) Br2, Et2O, 90%; (c) DBU, DMSO, 120 °C, 86%; (d)
SiO2, TFA, water, CH2Cl2, 90%; (e) n-BuLi, Ph3PCH3Br, THF, 62%; (f) (1) 9-BBN-H, THF, (2) NaOH, H2O2, 59%; (g) (1) KOH, ethanol,
water, 25 °C, (2) HCl, 73%; (h) DIAD, PPh3, CH3COSH, THF, 0-20 °C, 93%; (i) (1) KOH, ethanol, water, reflux, (2) HCl, 64%.
unbound GST protein was recovered and its concentra-
tion determined from its UV absorption at 276 nm using
the extinction coefficient.12 The percentage of GST-
glutathione-agarose complex was then plotted as a
function of the analogue concentration (Figure 2). The
dissociation plots obtained were used to determine the
IC50 values (Table 1). Our affinity chromatography test
has been compared with a more typical and sensitive
but also more expensive method, i.e., the ELISA-based
assay using a commercially available anti-GST mono-
clonal antibody (Sigma). The observed results are
within a similar value.12
moieties and thiol group of 14a . The importance of
these carboxylic acid groups was already emphasized
by Adang et al.11 and is clearly demonstrated here.
With only these two carboxylic acid groups present, the
IC50 value was still 5.2 µM. It is also noteworthy that
the carbon structure of 14a is that of GSH with three
and five methylene groups between the terminal car-
boxylic acid and the mercaptomethyl groups (see Table
1).
The compounds examined in this study were divided
into three classes as compared to 14a : first compounds
14c,f with a one-methylene group extension, then
compounds with removal of one methylene group (14b,d),
and finally symmetrical compounds with an equal
number of methylene groups on either side (14e, 23, and
25).
For compounds 14c,f, the extension of one methylene
group either on the “Glu side” or on the “Gly side”
resulted in a total loss of affinity and no binding was
detected. This indicates that the GST G binding site is
very selective. Although some distances between dif-
ferent binding regions can be assessed from known GST
X-ray data,25 dynamic interactions of a GSH analogue
and its binding site are difficult to predict. Our results
suggest that the binding pocket must be very tight and
rigid and cannot accommodate a one-carbon elongation
of the GSH backbone structure. This could also indicate
that the extended analogues cannot fold inside the
binding site in order to interact with their enzyme
binding region. This differs from the results of Adang
et al.,11 particularly for the Gly-extended analogue 14c.
In contrast, the compounds lacking one methylene
group, 14b,d , exhibited interesting binding affinities
(Table 1). The most potent was 14d (IC50 ) 10.0 µM)
which was only 2-fold less selective compared to 14a
and 500-fold less selective compared to glutathione.
Resu lts a n d Discu ssion
In the current study, we explored structural require-
ments for new nonpeptidic GSH analogues lacking
amide bonds. For this purpose we prepared a series of
analogues shown in Table 1. Their affinity for a
recombinant GST was evaluated (Figure 2), and we
determined their IC50 values (Table 1). It is important
to note that our binding experiments12 gave excellent
displacement curves (Figure 2) in accordance with
known GSH affinity. In the series of compounds studied
(Table 1) a first general IC50 examination indicates that
a substantial structure-affinity relationship exists.
Depending on the analogue, the IC50 values vary
between 5.2 µM and no measurable affinity (NA). Thus
our initial question concerning the influence of chain
length on the affinity is fully justified. The results
clearly indicate that the most potent analogue is 14a
with an IC50 value of 5.2 µM. This IC50 is substantial
and noteworthy when considering the simplicity of
structure 14a in comparison with the GSH structure.
Indeed, compound 14a has only a 250-fold weaker IC50
than GSH. This also indicates that the binding interac-
tions are concentrated around the two carboxylic acid

2282 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13
Ta ble 1. Affinity of the Analogues for GST Enzyme
Klotz et al.
group also plays an important role in binding affinity,
at least with respect to its position on the carbon chain.
A one-carbon displacement of this group (from 14a to
14e) resulted in a total loss of affinity, attributed to the
presence of unfavorable steric or electronic interactions.
The analogues may be rigidly bound to the G site of the
protein, and in the case of 14e, the space available for
the mercaptomethyl group in the G active site is not
large enough to accommodate this positional variation.
Addition of a peptide isosteric E double bond gave
compound 25, which also did not show any affinity for
the GST enzyme. If we consider that the peptide
isosteric E double bond can bring some additional
binding interactions, it is clearly not strong enough to
overcome the unfavorable steric or electronic interac-
tions of 14e. Changing the bulky thiol group for the
more polar hydroxyl group in 23 did not change the
affinity for the GST enzyme.
It is important to note that all the compounds were
synthesized and biologically evaluated in their racemic
forms. It would be interesting to observe any differences
in binding activities among the pure enantiomeric forms
of these compounds, especially for the more potent 14a .
Indeed, the importance of the chiral Cys center in GSH
was previously demonstrated.11 The affinity enhance-
ment that was observed for the LTD4 analogues when
adding an amide isosteric E double bond must also be
verified for compound 14a .
Con clu sion
As part of a program concerning the synthesis of
peptidostable LTC4 analogues, a series of original GSH
analogues lacking peptide bonds were prepared. Their
affinities for a recombinant GST enzyme were evaluated
in order to assess the optimal chain length of the
analogues 1 and the influence of a peptide isosteric E
double bond.
The synthesized analogues (Table 1) show significant
structure-affinity relationships. Our studies show that
synthesis of nonpeptidic GSH analogues with potent
affinities is possible with compound 14a . The structural
requirements are the two carboxylic acid groups and
perhaps the mercaptomethyl group. It was demon-
strated that the carbon skeleton must conserve that of
GSH which is an undecane carbon chain with the
carboxylic acids in positions 1 and 11. The mercaptom-
ethyl group must remain at position 5 as was deduced
from analogue 14e. Starting from 14a , it was shown
that a chain length elongation of one methylene group
leads to a total loss of affinity (14c,f). Chain length
reduction of one methylene group is not detrimental to
the affinity. Moreover, chain shortening at the “Glu
side” branch (14d ) is tolerated much more than at the
“Gly side” branch (14b). Addition of a peptide isosteric
E double bond in 25 did not recover affinity, even with
a less bulky hydroxyl group (23).
From this work compound 14a emerged as the best
GSH analogue. Its high affinity will allow us to develop
further peptidostable LTC4 analogues. Better GSH
analogues may be obtained with the synthesis of pure
enantiomeric forms of 14a with or without E-unsatur-
ated double bonds. Since LTD4 is formed before
LTE4,26,27 the Glu-Cys amide bond is metabolically
much more labile then the Cys-Gly amide bond.
These results reveal that shortening the glutathione
backbone by one methylene group on the “Glu side”
results in only a weak decrease in affinity of 14d
compared to 14a . This suggests that the Glu carboxylic
acid group can orient in the pocket site to interfere with
the enzyme binding region. This is not the case for
compound 14b and the Gly carboxylic acid group.
Indeed, in 14b, removing one carbon of the Gly branch
showed a significant decrease in affinity (IC50 ) 1800
µM). It seems that the carboxylic acid group in 14b
cannot interact properly with the enzyme binding
region. This weak affinity may be due to the greater
distance between the two interacting sites. In this case
we could assume that the major coordinating group
would be the “Gly side” carboxylic acid group.
The symmetrical compounds 14e, 23, and 25 did not
show any affinity for GST. As seen for compound 14d ,
shortening the “Glu side” branch did not significantly
reduce the affinity. This should also be true for the
reduced “Glu side” chain in 14e. The total loss of
affinity is likely due to additional elongation of the “Gly
side” chain in 14e. This symmetrical compound cannot
interfere properly within the active binding site. In-
terestingly, 14e possesses the same number of carbons
as the best analogue 14a . From this point of view, only
the mercaptomethyl group is shifted from carbon posi-
tion 5 to 6. This suggests that the mercaptomethyl

Nonpeptidic and Peptidase-Stable GSH Analogues
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13 2283
chloride 7 (10.50 mL, 85.08 mmol). After filtration the solid
was crystallized from water and gave pure 10b as a beige solid
(8.600 g, 52% yield): TLC (chloroform/acetic acid, 9/1) Rf 0.43;
mp 108-109 °C (recrystallized from water); 1H NMR (CD3-
OD) δ 1.22-1.78 (m, 6H, H6-8), 2.29 (t, J ) 7.0, 2H, H9), 2.44-
2.58 (m, 4H, H2,5), 2.67-2.80 (m, 2H, H3), 5.01 (s broad, 2H,
OH); 13C NMR (CD3OD) δ 24.44, 25.82, 28.64, 29.67, 34.72,
37.90, 176.49, 177.53, 211.71; MS (GT) m/z 217 (M + H)+, 199
(M - OH)+. Anal. (C10H16O5) C, H.
Therefore, replacement of only the more labile peptidic
bond by a simple carbon-carbon bond or an E olefinic
double bond is also being considered.
These results should provide additional insight in
mapping the length and breadth of the GST G site
binding pocket.
Exp er im en ta l Section
6-Oxo-1,12-d od eca n ed ioic Acid (10c). Prepared as 10a
starting from enamine 6 (14.80 mL, 88.04 mmol) and acid
chloride 9 (16.50 mL, 96.99 mmol). After filtration the solid
was crystallized from chloroform and recrystallized from water
and gave pure 10c as a beige solid (14.130 g, 66% yield): TLC
(chloroform/acetic acid, 9/1) Rf 0.47; mp 109-110 °C (recrystal-
lized from water); 1H NMR (CD3OD) δ 1.20-1.70 (m, 10H,
H3,4,8-10), 2.29 (t, J ) 7.3, 4H, H2,11), 2.47 (t, J ) 6.7, 4H, H5,7),
4.92 (s broad, 2H, OH); 13C NMR (CD3OD) δ 25.14, 25.34,
26.41, 26.70, 30.59, 35.54, 35.59, 43.89, 44.04, 178.21, 178.38,
214.37; MS (GT) m/z 245 (M + H)+, 227 (M - OH)+. Anal.
(C12H20O5) C, H.
5-Oxo-1,10-d eca n ed ioic Acid (10d ). Prepared as 10a
starting from enamine 5 (8.00 g, 52.21 mmol) and acid chloride
8 (7.95 mL, 57.53 mmol). After filtration the solid was
crystallized from chloroform to afford pure keto diacid 10d as
a beige solid (6.950 g, 62% yield). The product was further
recrystallized in water: TLC (chloroform/acetic acid, 9/1) Rf
0.39; mp 116-117 °C (recrystallized from water); 1H NMR
(CD3OD) δ 1.59-1.68 (m, 4H, H7,8), 1.82-1.93 (m, 2H, H3),
2.29-2.42 (m, 4H, H2,9), 2.50-2.54 (m, 2H, H6), 2.57 (t, J )
7.2, 2H, H4), 4.99 (s broad, 2H, OH); 13C NMR (CD3OD) δ 20.05,
24.25, 25.53, 33.92, 34.66, 42.29, 43.03, 177.03, 177.35, 212.73;
IR (KBr) ν 3500-2500, 1700, 1660, 1420, 1400, 1270, 910; MS
(NBA) m/z 239 (M + Na)+, 217 (M + H)+, 199 (M - OH)+.
Anal. (C10H16O5) C, H.
6-Oxo-1,11-u n d eca n ed ioic Acid (10e). Prepared as 10a
starting from enamine 5 (12.60 mL, 78.69 mmol) and acid
chloride 9 (14.75 mL, 86.71 mmol). After filtration the solid
was crystallized from chloroform to afford pure keto diacid 10e
as a beige solid (12.141 g, 67% yield). The product was further
recrystallized in water: TLC (chloroform/acetic acid, 9/1) Rf
0.45; mp 110-111 °C (recrystallized from water); 1H NMR
(CD3OD) δ 1.50-1.70 (m, 8H, H3,4,8,9), 2.15-2.40 (m, 4H, H2,10),
2.42-2.59 (m, 4H, H5,7), 4.93 (s broad, 2H, OH); 13C NMR (CD3-
OD) δ 24.24, 25.52, 34.65, 42.97, 177.32, 213.23; IR (KBr) ν
3200-3000, 2940, 1680 broad, 1465, 1400, 1330, 1260, 1200,
900; MS (NBA) m/z 253 (M + Na)+, 231 (M + H)+, 213 (M -
OH)+. Anal. (C11H18O5) C, H.
Dim eth yl 5-Oxo-1,11-u n d eca n ed ioa te (11a ). In a dried
round-bottomed flask under argon were introduced the start-
ing keto diacid 10a (7.002 g, 30.41 mmol), DCC (13.817 g,
66.966 mmol), and DMAP (1.866 g, 15.274 mmol). The
reaction was started with the rapid addition of freshly distilled
CH2Cl2 (300 mL) and dry methanol (2.70 mL, 66.66 mmol).
The mixture was vigorously stirred at room temperature for
18 h. Concentrated acetic acid was then added to the reaction
(0.87 mL, 15.20 mmol) which was stirred for several hours to
eliminate the remaining DCC (monitored by TLC, ca. 2 h). The
formed DCU was then filtered off and washed with ethyl ether.
The solvents were removed in vacuo, and the crude solid was
taken up in ethyl ether (50 mL), filtered, and washed once
more to eliminate the maximum amount of DCU. After
removal of the solvent in vacuo, the crude material was
chromatographed on a silica gel column (heptanes/EtOAc, 7/3)
to give diester 11a as a white solid (7.341 g, 94% yield): TLC
(heptanes/EtOAc, 6/4) Rf 0.45; mp 37-38 °C (from column
chromatography); 1H NMR (CDCl3) δ 1.10-1.69 (m, 6H, H7-9),
1.70-2.00 (m, 2H, H3), 2.19-2.52 (m, 8H, H2,4,6,10), 3.62 (s, 6H,
OCH3); 13C NMR (CDCl3) δ 18.75, 23.22, 24.55, 28.52, 32.93,
33.71, 41.38, 42.38, 51.37, 51.42, 173.50, 173.93, 209.88; IR
(KBr) ν 2920, 2860, 1720, 1700, 1420, 1370, 1340, 1250, 1220,
1180, 1150, 1100, 965, 870; MS (GT) m/z 259 (M + H)+, 227
(M - OCH3)+, 195 (M - 2OCH3 - H)+. Anal. (C13H22O5) C,
H.
Melting points were determined on a Bu¨chi Tottoli capillary
apparatus and are not corrected. 1H and 13C NMR spectra
were recorded either on a Bruker AC100 spectrometer at 100
and 25 MHz, respectively, or on a Bruker AMX360 at 360 and
90 MHz, respectively; 2D NMR spectra were recorded on a
Bruker AMX360 spectrometer. Chemical shifts (δ) are quoted
in ppm, and coupling constants (J ) are given in Hz. The
residual hydrogenated solvent peak was used as internal
reference (CHCl3, δH 7.27 ppm, δC 77.0 ppm; CH3OH, δH 3.31
ppm, δC 49.0 ppm). Mass spectra were recorded on a J EOL
J MS DX 300 spectrometer in the FAB+ mode with 2-nitroben-
zyl alcohol (NBA) or glycerol-thiol (GT) as matrix. Infrared
spectra were obtained on a Beckman AccuLab2 spectropho-
tometer, and absorption bands (ν) are given in cm-1. Elemen-
tal analyses were performed at the Service de Microanalyses
de l′ENSCM at Montpellier (France), the maximum error being
in the range of (0.4% of calcd. Analytical TLC was performed
on Merck silica gel 60 F254, precoated 0.25-mm glass-backed
plates. Visualization methods included UV light, iodine
vapors, and phosphomolybdic acid or anisaldehyde dipping.
Column chromatography was performed with Merck silica gel
Geduran 40-63 or 63-200 µm particle size. All air-sensitive
experiments were carried out under argon with freshly dis-
tilled dried solvents. Chloroform and thiolacetic acid were
distilled prior to use. Methylene chloride (CH2Cl2) and N,N-
dimethylacetamide (DMA) were distilled from CaH2. THF was
distilled from sodium-benzophenone. Triethylamine (Et3N)
was dried over KOH. Benzene and ethyl ether were dried by
standing over sodium wire. Methanol was distilled after
reaction with sodium. Acetone was dried over anhydrous
CaSO4. DMSO was purchased anhydrous and kept over 4-Å
molecular sieves.
5-Oxo-1,11-u n d eca n ed ioic Acid (10a ). To a stirred solu-
tion of enamine 6 (9.15 mL, 54.69 mmol) and Et3N (9.20 mL,
66.01 mmol) in dry CH2Cl2 (70 mL) at room temperature was
added the acid chloride 8 (10.0 g, 60.76 mmol) diluted in CH2-
Cl2 (30 mL) dropwise. A white precipitate appeared during
the addition. The mixture was stirred at room temperature
for 1 h and under reflux for 3 h. The reaction was then
carefully hydrolyzed by addition of HCl (18%, 30 mL) and
heated under reflux (bath temperature 50 °C) for 4 h. After
cooling to room temperature, the water phase was extracted
with CH2Cl2. The combined organic extracts were washed
with 1 N HCl, water and saturated NaCl, dried over MgSO4,
and concentrated in vacuo. The brown crude residue was
dissolved in a KOH solution (12.75 g, 227 mmol in 13 mL
water) and heated at 100 °C for 30 min. After the mixture
cooled to room temperature, a minimum amount of water (47
mL) was added to allow the dissolution of the KCl formed in
the next acidification step (KCl solubility in water: 1 g/2.8 mL
at 20 °C). The reaction was ice-cooled and carefully acidified
to pH 1 with concentrated HCl. The formed precipitate was
filtred, washed with cold water, and lyophilized. The solid was
then crystallized from chloroform to afford pure keto diacid
10a as a beige solid (8.022 g, 64% yield). The product was
further recrystallized in water: TLC (chloroform/acetic acid,
1
9/1) Rf 0.37; mp 102-103 °C (recrystallized from water); H
NMR (CD3OD) δ 1.20-2.02 (m, 8H, H3,7-9), 2.20-2.40 (m, 4H,
H
2,10), 2.40-2.67 (m, 4H, H4,6), 5.09 (s broad, 2H, OH); 13C NMR
(CD3OD) δ 20.03, 24.45, 25.80, 29.68, 33.90, 34.70, 42.31, 43.21,
176.99, 177.50, 213.02; IR (KBr) ν 3400-2400, 1680 broad,
1400, 1260, 1090, 1070, 900; MS (GT) m/z 231 (M + H)+, 213
(M - OH)+, 185 (M - CO2H)+. Anal. (C11H18O5) C, H.
4-Oxo-1,10-d eca n ed ioic Acid (10b). Prepared as 10a
starting from enamine 6 (13.00 mL, 77.35 mmol) and acid

2284 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13
Klotz et al.
Dim eth yl 4-oxo-1,10-Deca n ed ioa te (11b). Prepared as
11a starting from 10b (7.490 g, 34.64 mmol). Purification by
silica gel column chromatography (heptanes/EtOAc, 7/3) af-
forded 11b as a colorless oil that solidified on cooling (6.815
g, 81% yield): TLC (heptanes/EtOAc, 7/3) Rf 0.33; 1H NMR
(CDCl3) δ 1.24-1.70 (m, 6H, H6-8), 2.31 (t, J ) 7.7, 2H, H9),
2.46 (t, J ) 7.0, 2H, H2), 2.48-2.76 (m, 4H, H3,5), 3.66 (s, 3H,
OCH3), 3.67 (s, 3H, OCH3); 13C NMR (CDCl3) δ 23.26, 24.61,
27.65, 28.55, 33.78, 36.98, 42.40, 51.45, 51.74, 173.24, 174.02,
208.74; IR (film) ν 2930, 2850, 1715 broad, 1420, 1400, 1350,
1190, 1160, 1090, 1000, 975, 840; MS (GT) m/z 245 (M + H)+,
213 (M - OCH3)+, 181 (M - 2OCH3 - H)+. Anal. (C12H20O5)
C, H.
temperature 90 °C) for 4 h. After the mixture was cooled to
60 °C, a solution of Pd(0) catalyst (0.3098 g, 0.2681 mmol) in
dry benzene (8.2 mL) was added, and stirring was continued
for 10 min at 60 °C. The heating bath was then removed, a
solution of acid chloride 8 (3.70 mL, 26.77 mmol) in dry
benzene (5.4 mL) was added dropwise to the reaction mixture,
and stirring was continued for 1 h until the reaction was
complete (TLC monitored). The suspension was filtered
through a Celite pad which was washed with ethyl ether. The
filtrate was then washed successively with 10% NH4Cl, 10%
NaHCO3, and saturated NaCl solutions, dried over MgSO4,
and concentrated in vacuo. The crude brown oil was then
purified on a silica gel chromatography column (heptanes/
EtOAc, 7/3) followed by distillation in a Kugelrohr apparatus
(160-180 °C, 0.5 mmHg) to give pure 11f (6.149 g, 80% yield)
as a white solid at room temperature: TLC (heptanes/EtOAc,
7/3) Rf 0.40; mp 37 °C (from column chromatography); 1H NMR
(CDCl3) δ 1.23 (t, J ) 6.2, 3H, CH3C), 1.28-1.70 (m, 8H, H7-10),
1.78-2.00 (m, 2H, H3), 2.18-2.52 (m, 8H, H2,4,6,11), 3.64 (s, 3H,
OCH3), 4.09 (q, J ) 7.1, 2H, CH2O); 13C NMR (CDCl3) δ 14.17,
18.79, 23.49, 24.67, 28.78 (2C), 32.96, 34.16, 41.39, 42.62,
51.46, 60.10, 173.54, 173.64, 210.10; MS (GT) m/z 287 (M +
H)+, 255 (M - OCH3)+, 210 (M - OCH3 - OEt - H)+. Anal.
(C15H26O5) C, H.
Dim eth yl 6-Oxo-1,12-d od eca n ed ioa te (11c). Prepared
as 11a starting from 10c (0.493 g, 2.018 mmol). Purification
by silica gel column chromatography (heptanes/EtOAc, 7/3)
afforded 11c as a colorless oil that solidified when refrigerated
1
(0.446 g, 81% yield): TLC (heptanes/EtOAc, 6/4) Rf 0.52; H
NMR (CDCl3) δ 1.12-1.51 (m, 2H, H9), 1.51-1.71 (m, 8H,
H3,4,8,10), 2.22-2.50 (m, 8H, H2,5,7,11), 3.65 (s, 6H, OCH3); 13C
NMR (CDCl3) δ 23.01, 23.16, 24.27, 24.49, 28.47, 33.63 (2C),
42.11, 42.28, 51.30 (2C), 173.61, 173.83, 210.23; IR (film) ν
2930, 2860, 1715 broad, 1425, 1365, 1185, 1160, 990; MS (GT)
m/z 273 (M + H)+, 241 (M - OCH3)+. Anal. (C14H24O5) C, H.
Dim eth yl 5-Meth ylen e-1,11-u n d eca n ed ioa te (12a ). In
a dried round-bottomed flask under argon were introduced
t-BuOK (1.700 g, 15.15 mmol) and Ph3PCH3Br (5.436 g, 15.22
mmol). The ylide formation was started with the addition of
freshly distilled THF (60 mL). The yellow suspension was then
stirred at room temperature for 3 h, and a solution of the keto
diester 11a (3.020 g, 11.69 mmol) in freshly distilled THF (12
mL) was then added with a syringe to the ylide. The reaction
mixture was stirred for 16 h and quenched with 10% aqueous
NH4Cl (40 mL), and heptanes (120 mL) was added. The layers
were separated, and the water phase was extracted with
heptanes (2 × 50 mL). The combined heptanes extract was
washed with water and saturated NaCl, dried over MgSO4,
and concentrated in vacuo. The crude product, containing the
formed triphenylphosphine oxide, was taken up in ethyl ether
(50 mL), filtered, and washed with ethyl ether. The collected
filtrate was concentrated in vacuo, and the residue was
purified by silica gel column chromatography (heptanes/EtOAc,
9/1 to 85/15) to afford 12a (2.299 g, 77% yield) as a colorless
liquid: (TLC heptanes/EtOAc, 85/15) Rf 0.35; 1H NMR (CDCl3)
δ 1.27-1.85 (m, 8H, H3,7-9), 1.86-2.10 (m, 4H, H4,6), 2.30 (t, J
) 7.2, 4H, H2,10), 3.65 (s, 6H, OCH3), 4.70 (s broad, 2H, CH2d);
13C NMR (CDCl3) δ 22.80, 24.74, 27.22, 28.75, 33.44, 33.95,
35.16, 35.50, 51.38 (2C), 109.56, 148.39, 174.01, 174.14; IR
(film) ν 3050, 2910, 2830, 1710, 1620, 1415, 1340, 1225, 1180,
1150, 1070, 990, 870; MS (GT) m/z 257 (M + H)+, 243 (M -
CH)+, 225 (M - OCH3)+, 193 (M - 2OCH3 - H)+. Anal.
(C14H24O4) C, H.
Dim eth yl 4-Meth ylen e-1,10-d eca n ed ioa te (12b). Pre-
pared as 12a starting from 11b (5.832 g, 23.87 mmol).
Purification by silica gel column chromatography (heptanes/
ethyl ether, 8/2) afforded 12b as a colorless liquid (4.561 g,
79% yield): TLC (heptanes/ethyl ether, 8/2) Rf 0.27; 1H NMR
(CDCl3) δ 1.30-1.80 (m, 6H, H6-8), 1.95-2.10 (m, 2H, H3),
2.24-2.60 (m, 6H, H2,5,9), 3.65 (2s, 6H, OCH3), 4.71-4.74 (m,
2H, CH2d); 13C NMR (CDCl3) δ 24.76, 27.25, 28.74, 30.72,
32.47, 33.99, 35.96, 51.45, 51.55, 109.29, 147.84, 173.75,
174.18; IR (film) ν 2920, 2850, 1725, 1630, 1425, 1345, 1240,
1185, 1155, 980; MS (GT) m/z 243 (M + H)+, 211 (M - OCH3)+,
179 (M - 2OCH3 - H)+. Anal. (C13H22O4) C, H.
Dim eth yl 5-Oxo-1,10-d eca n ed ioa te (11d ). Prepared as
11a starting from 10d (2.002 g, 9.258 mmol). Purification by
silica gel column chromatography (heptanes/EtOAc, 6/4) af-
forded 11d as a colorless oil that solidifies when refrigerated
1
(2.126 g, 94% yield): TLC (heptanes/EtOAc, 7/3) Rf 0.25; H
NMR (CDCl3) δ 1.53-1.62 (m, 4H, H7,8), 1.85 (tt, 2H, J ) 7.2,
H3), 2.25-2.34 (m, 4H, H2,9), 2.35-2.40 (m, 2H, H6), 2.44 (t, J
) 7.2, 2H, H4), 3.63 (s, 6H, OCH3); 13C NMR (CDCl3) δ 18.75,
23.05, 24.32, 32.93, 33.70, 41.40, 42.23, 51.46 (2C), 173.52,
173.73, 209.56; IR (film) ν 2940, 2860, 1720, 1700, 1425, 1360,
1240, 1190, 1150, 1005; MS (NBA) m/z 267 (M + Na)+, 245
(M + H)+, 213 (M - OCH3)+, 181 (M - 2OCH3 - H)+. Anal.
(C12H20O5) C, H.
Dim eth yl 6-Oxo-1,11-u n d eca n ed ioa te (11e). Prepared
as 11a starting from 10e (6.530 g, 28.36 mmol). Purification
by silica gel column chromatography (heptanes/EtOAc, 7/3)
afforded 11e as a colorless oil that solidifies when refrigerated
1
(6.939 g, 95% yield): TLC (heptanes/EtOAc, 6/4) Rf 0.44; H
NMR (CDCl3) δ 1.45-1.74 (m, 8H, H3,4,8,9), 2.23-2.49 (m, 8H,
H
2,5,7,10), 3.67 (s, 6H, OCH3); 13C NMR (CDCl3) δ 23.14, 24.40,
33.78, 42.29, 51.52, 173.82, 210.11; IR (film) ν 2940, 2860,
1725, 1700, 1425, 1405, 1360, 1235, 1190, 1160, 1000; MS
(NBA) m/z 281 (M + Na)+, 259 (M + H)+, 227 (M - OCH3)+,
195 (M - 2OCH3 - H)+. Anal. (C13H22O5) C, H.
Eth yl 7-Iod oh ep ta n oa te (16). Ethyl 7-bromoheptanoate
(15) (10.0 mL, 51.32 mmol) was dissoved in dry acetone (100
mL) containing NaI (38.825 g, 259.02 mmol). The mixture was
stirred under reflux for 20 h, cooled to room temperature, and
allowed to stand for 20 h. The crystallized salts were filtered
and washed with ethyl ether and CH2Cl2. Solvents were
evaporated in vacuo, and ethyl ether (50 mL) was added to
the crude residue. This organic phase was then washed with
10% Na2S2O4 solution, water, and saturated NaCl, dried over
MgSO4, and concentrated in vacuo. The crude residue was
rapidly chromatographed on a silica gel column (heptanes/CH2-
Cl2, 8/2 to 6/4) and the obtained product distilled with a
Kugelrohr apparatus (130-140 °C, 0.5 mmHg) to give pure
16 as a slightly yellowish liquid (12.723 g, 87% yield): TLC
(heptanes/ethyl ether, 8/2) Rf 0.51; 1H NMR (CDCl3) δ 1.26 (t,
J ) 7.2, 3H, CH3), 1.34-1.90 (m, 8H, H3-6), 2.31 (t, J ) 7.1,
2H, H2), 3.19 (t, J ) 6.9, 2H, H7), 4.13 (q, J ) 7.1, 2H, OCH2);
13C NMR (CDCl3) δ 6.92, 14.21, 24.66, 27.95, 30.06, 33.19,
34.15, 60.19, 173.65; MS (GT) m/z 307 (M + Na)+, 285 (M +
H)+, 239 (M - OEt)+. Anal. (C9H17IO2) C, H.
Dim eth yl 6-Meth ylen e-1,12-d od eca n ed ioa te (12c). Pre-
pared as 12a starting from 11c (6.020 g, 22.10 mmol).
Purification by silica gel column chromatography (heptanes/
EtOAc, 9/1) afforded 12c as a colorless liquid (4.961 g, 83%
1
yield): TLC (heptanes/EtOAc, 9/1) Rf 0.38; H NMR (CDCl3)
1-Meth yl 12-Eth yl 5-Oxod od eca n ed ioa te (11f). To a
stirred suspension of zinc-copper couple (3.000 g, 45,893
mmol) in dry benzene (10.8 mL) was added the iodide
compound 16 (8.803 g, 30.98 mmol) in a mixture of dry benzene
(38.0 mL) and DMA (5.0 mL). The suspension was vigorously
stirred at room temperature for 2 h and under reflux (bath
δ 1.33-1.80 (m, 10H, H3,4,8-10), 1.93-2.08 (m, 4H, H5,7), 2.31
(t, J ) 7.4, 4H, H2,11), 3.67 (s, 6H, OCH3), 4.70 (s broad, 2H,
CH2d); 13C NMR (CDCl3) δ 24.45, 24.64, 26.99, 27.15, 28.66,
33.73, 33.82, 35.38, 35.50, 51.22 (2C), 108.92, 148.90, 173.88,
173.96; IR (film) ν 3060, 2920, 2840, 1720 broad, 1625, 1420,

Nonpeptidic and Peptidase-Stable GSH Analogues
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13 2285
1340, 1180, 1150, 990, 870; MS (GT) m/z 271 (M + H)+, 239
1420, 1345, 1240, 1190, 1160, 1125, 1100, 1000, 945, 615; MS
(M - OCH3)+, 207 (M - 2OCH3 - H)+. Anal. (C15H26O4) C,
(GT) m/z 319 (M + H)+, 287 (M - OCH3)+, 245 (M - OCH3
-
H.
CH3CO + H or M - CH3COS + 2H)+, 213 (M - 2OCH3 - CH3-
CO)+.
Dim eth yl 5-Meth ylen e-1,10-d eca n ed ioa te (12d ). Pre-
pared as 12a starting from 11d (1.585 g, 6.488 mmol).
Purification by silica gel column chromatography (heptanes/
EtOAc, 85/15) afforded 12d as a yellowish liquid (1.290 g, 82%
Dim eth yl 6-[(Acetylth io)m eth yl]-1,12-d od eca n ed ioa te
(13c). Prepared as 13a starting from 12c (2.517 g, 9.31 mmol)
and AIBN (40 mg). Purification by two silica gel column
chromatographies (heptanes/EtOAc, 85/15) afforded 13c as a
yellowish oil (2.680 g, 83% yield): TLC (heptanes/EtOAc, 8/2)
1
yield): TLC (heptanes/EtOAc, 8/2) Rf 0.46; H NMR (CDCl3)
δ 1.30-2.06 (m, 10H, H3,4,6-8), 2.28 (t, J ) 6.9, 4H, H2,9), 3.63
(s, 6H, OCH3), 4.69 (s broad, 2H, CH2d); 13C NMR (CDCl3) δ
22.70, 24.44, 26.94, 33.34, 33.75, 35.02, 35.25, 51.31 (2C),
109.73, 147.93, 173.90 (2C); IR (film) ν 3070, 2940, 2850, 1725
broad, 1630, 1420, 1350, 1235, 1190, 1160, 1070, 1000, 880;
MS (NBA) m/z 265 (M + Na)+, 243 (M + H)+, 211 (M -
OCH3)+, 179 (M - 2OCH3 - H)+. Anal. (C13H22O4) C, H.
Dim eth yl 6-Meth ylen e-1,11-u n decan edioate (12e). Pre-
pared as 12a starting from 11e (2.050 g, 7.94 mmol). Purifica-
tion by silica gel column chromatography (heptanes/EtOAc,
85/15) afforded 12e as a yellowish liquid (1.661 g, 82% yield):
TLC (heptanes/EtOAc, 8/2) Rf 0.47; 1H NMR (CDCl3) δ 1.26-
1.77 (m, 8H, H3,4,8,9), 2.01 (t, J ) 6.9, 4H, H5,7), 2.33 (t, J )
7.2, 4H, H2,10), 3.67 (s, 6H, OCH3), 4.71 (s broad, 2H, CH2d);
13C NMR (CDCl3) δ 24.54, 27.06, 33.86, 35.43, 51.40, 109.25,
148.66, 174.07; IR (film) ν 3070, 2940, 2860, 1730, 1635, 1430,
1360, 1230, 1190, 1165, 880; MS (NBA) m/z 279 (M + Na)+,
257 (M + H)+, 225 (M - OCH3)+, 193 (M - 2OCH3 - H)+.
Anal. (C14H24O4) C, H.
1-Meth yl 12-Eth yl 5-Meth ylen ed od eca n ed ioa te (12f).
Prepared as 12a starting from 11f (6.131 g, 21.41 mmol). After
the combined heptanes extracts were concentrated, the residue
was taken up in a mixture of heptanes/EtOAc (9/1, 50 mL).
Purification by silica gel column chromatography (heptanes/
EtOAc, 85/15) afforded 12f as a colorless liquid (5.066 g, 83%
yield): TLC (heptanes/EtOAc, 85/15) Rf 0.45; 1H NMR (CDCl3)
δ 1.25 (t, J ) 7.1, 3H, CH3C), 1.32-1.87 (m, 10H, H3,7-10),
1.90-2.11 (m, 4H, H4,6), 2.30 and 2.31 (2t, J ) 7.0, 7.4, 4H,
1
Rf 0.35; H NMR (CDCl3) δ 1.23-1.73 (m, 15H, H3-10), 2.21-
2.35 (m, 4H, H2,11), 2.30 (s, 3H, CH3CO), 2.85 (d, J ) 5.5, 2H,
CH2S), 3.64 (s, 6H, OCH3); 13C NMR (CDCl3) δ 24.72, 24.99,
26.02, 26.12, 29.20, 30.58, 32.72, 32.89, 33.10, 33.85, 33.90,
37.49, 51.35 (2C), 174.00, 174.08, 195.75; IR (film) ν 2920, 2850,
1725, 1680, 1425, 1355, 1235, 1185, 1160, 1125, 1095, 1000,
945, 610; MS (NBA) m/z 369 (M + Na)+, 347 (M + H)+, 315
(M - OCH3)+, 273 (M - OCH3 - CH3CO + H or M - CH3-
COS + 2H)+, 241 (M - 2OCH3 - CH3CO)+. Anal. (C17H30O5S)
C, H.
Dim et h yl 5-[(Acet ylt h io)m et h yl]-1,10-d eca n ed ioa t e
(13d ). Prepared as 13a starting from 12d (1.276 g, 5.27 mmol)
and AIBN (40 mg). Purification by two silica gel column
chromatographies (heptanes/EtOAc, 8/2) afforded 13d as a
yellowish oil (1.466 g, 87% yield): TLC (heptanes/EtOAc, 8/2)
Rf 0.29; 1H NMR (CDCl3) δ 1.23-1.31 (m, 6H, H4,6,7), 1.52-
1.61 (m, 5H, H3,5,8), 2.22-2.26 (m, 4H, H2,9), 2.28 (s, 3H, CH3-
CO), 2.84 (d, J ) 6.0, 2H, CH2S), 3.62 (s, 6H, OCH3); 13C NMR
(CDCl3) δ 21.98, 25.04, 26.05, 30.67, 32.57, 32.67, 33.01, 33.91,
34.10, 37.51, 51.46 (2C), 173.88, 174.04, 195.72; IR (film) ν
2930, 2880, 1725, 1680, 1430, 1350, 1240-1100, 950, 615; MS
(NBA) m/z 341 (M + Na)+, 319 (M + H)+, 245 (M - OCH3
-
CH3CO + H or M - CH3COS + 2H)+, 213 (M - 2OCH3 - CH3-
CO)+. Anal. (C15H26O5S) C, H,O.
Dim eth yl 6-[(Acetylth io)m eth yl]-1,11-u n d eca n ed ioa te
(13e). Prepared as 13a starting from 12e (0.250 g, 0.975
mmol) and AIBN (15 mg). Purification by silica gel column
chromatography (heptanes/EtOAc, 8/2) afforded 13e as a
yellowish oil (0.308 g, 95% yield): TLC (heptanes/EtOAc, 8/2)
H
4,6), 3.67 (s, 3H, OCH3), 4.12 (q, J ) 7.0, 2H, CH2O), 4.72 (s
broad, 2H, CH2d); 13C NMR (CDCl3) δ 14.24, 22.89, 24.92,
27.50, 28.99 (2C), 33.54, 34.34, 35.25, 35.74, 51.45, 60.15,
109.51, 148.66, 173.84, 174.09; IR (film) ν 3060, 2960, 2920,
2840, 1730, 1710, 1630, 1420, 1350, 1250-1120, 1085, 1020,
880; MS (GT) m/z 285 (M + H)+, 253 (M - OCH3)+, 239 (M -
EtO)+, 207 (M - OCH3 - EtO - H)+. Anal. (C16H28O4) C, H.
1
Rf 0.30; H NMR (CDCl3) δ 1.22-1.34 (m, 8H, H4,5,7,8), 1.51-
1.64 (m, 5H, H3,9), 2.28 (t, J ) 7.5, 4H, H2,10), 2.29 (s, 3H, CH3-
CO), 2.85 (d, J ) 6.0, 2H, CH2S), 3.64 (s, 6H, OCH3); 13C NMR
(CDCl3) δ 25.03, 26.05, 30.65, 32.73, 33.05, 33.90, 37.44, 51.43,
174.06, 195.82; IR (film) ν 2910, 2840, 1720, 1675, 1420, 1340,
1230-1080, 940, 610; MS (NBA) m/z 355 (M + Na)+, 333 (M
+ H)+, 259 (M - OCH3 - CH3CO + H or M - CH3COS +
2H)+, 227 (M - 2OCH3 - CH3CO)+.
Dim eth yl 5-[(Acetylth io)m eth yl]-1,11-u n d eca n ed ioa te
(13a ). In
a pear-shaped flask flushed with argon were
introduced the olefin 12a (1.004 g, 3.92 mmol), freshly distilled
thiolacetic acid (1.10 mL, 15.39 mmol), and AIBN (40 mg). The
mixture was stirred at 90 °C for 6 h, then cooled to room
temperature, and diluted with ethyl ether (15 mL). The
organic phase was washed with water, 10% aqueous NaHCO3,
and saturated NaCl, dried over MgSO4, and concentrated in
vacuo. The crude product was purified by two silica gel column
chromatographies (heptanes/EtOAc, 8/2, and heptanes/ethyl
ether, 7/3) to give pure 13a as a yellowish oil (1.120 g, 86%
yield): TLC (heptanes/EtOAc) 75/25, Rf 0.43; 1H NMR (CDCl3)
δ 1.20-1.75 (m, 13H, H3-9), 2.31 (t, J ) 6.9, 4H, H2,10), 2.33
(s, 3H, CH3CO), 2.90 (d, J ) 5.6, 2H, CH2S), 3.67 (s, 6H, OCH3);
13C NMR (CDCl3) δ 21.92, 24.79, 26.15, 29.26, 30.67, 32.58,
32.84, 33.07, 33.98, 34.12, 37.60, 51.46 (2C), 173.94, 174.17,
195.83; IR (film) ν 2910, 2840, 1715, 1675, 1410, 1340, 1230-
1085, 995, 935, 610; MS (GT) m/z 333 (M + H)+, 301 (M -
OCH3)+, 259 (M - OCH3 - CH3CO + H or M - CH3COS +
2H)+, 227 (M - 2OCH3 - CH3CO)+. Anal. (C16H28O5S) C, H.
1-Meth yl 12-Eth yl 5-[(Acetylth io)m eth yl]d od eca n ed io-
a te (13f). Prepared as 13a starting from 12f (2.608 g, 10.17
mmol) and AIBN (80 mg). Purification by two silica gel column
chromatographies (heptanes/EtOAc, 9/1, and heptanes/ethyl
ether, 8/2) afforded 13f as a yellowish oil (2.981 g, 81% yield):
TLC (heptanes/EtOAc, 8/2) Rf 0.40; 1H NMR (CDCl3) δ 1.18-
1.75 (m, 18H, H3-10, CH3C), 2.22-2.37 (m, 4H, H2,11), 2.33 (s,
3H, CH3CO), 2.90 (d, J ) 5.6, 2H, CH2S), 3.67 (s, 3H, OCH3),
4.13 (q, J ) 7.1, 2H, CH2O); 13C NMR (CDCl3) δ 14.24, 22.04,
24.93, 26.36, 29.05, 29.45, 30.68, 32.64, 33.05, 33.17, 34.17,
34.33, 37.63, 51.48, 60.15, 173.82, 173.94, 195.83; MS (GT) m/z
360 (M + H)+, 287 (M - OCH3 - CH3CO + H)+, 273 (M -
EtO - CH3CO + H)+, 241 (M - OCH3 - EtO - CH3CO)+.
Anal. (C18H32O5S) C, H.
5-(Mer ca p tom eth yl)-1,11-u n d eca n ed ioic Acid (14a ). In
an argon-flushed flask, compound 13a (0,583 g, 1.752 mmol)
was dissolved in a mixture of ethanol and water (1/1, 6 mL)
containing KOH (85%, 0.990 g, 15.00 mmol). The reaction was
heated under reflux (bath temperature 100 °C) for 3 h, cooled
to room temperature, acidified with 3 N HCl (pH ca. 1), and
extracted with EtOAc. Small quantities of saturated NaCl
solution were added to resolve emulsions. The combined
organic extracts were washed with saturated NaCl, dried over
MgSO4, and concentrated in vacuo. The crude product was
purified by silica gel column chromatography (chloroform/
methanol, 95/5) to give pure thiol 14a as a colorless oil which
was placed under vacuum for 24 h to eliminate trace amounts
of solvents. The obtained oil was refrigerated and became a
Dim et h yl 4-[(Acet ylt h io)m et h yl]-1,10-d eca n ed ioa t e
(13b). Prepared as 13a starting from 12b (2.324 g, 9.59 mmol)
and AIBN (40 mg). Purification by two silica gel column
chromatographies (heptanes/EtOAc, 8/2, and heptanes/ethyl
ether, 7/3) afforded 13b as a yellowish oil (2.562 g, 84%
1
yield): TLC (heptanes/EtOAc, 8/2) Rf 0.29; H NMR (CDCl3)
δ 1.31 (s broad, 6H, H6-8), 1.57-1.70 (m, 5H, H3-5), 2.24-2.40
(m, 4H, H2,9), 2.34 (s, 3H, CH3CO), 2.90 (d, J ) 5.2, 2H, CH2S),
3.67 (s, 6H, OCH3); 13C NMR (CDCl3) δ 24.76, 26.12, 28.10,
29.22, 30.68, 31.32, 32.74, 32.81, 33.97, 37.32, 51.45, 51.57,
173.94, 174.16, 195.71; IR (film) ν 2920, 2850, 1720, 1680,

2286 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13
Klotz et al.
white solid (0.292 g, 64% yield): TLC (chloroform/methanol,
9/1) Rf 0.45; mp 43-44 °C (from column chromatography); 1H
NMR (CD3OD) δ 1.29-1.75 (m, 13H, H3-9), 2.29 (t, J ) 7.0,
4H, H2,10), 2.50-2.60 (m, 2H, CH2S), 4.94 (s broad, 3H, OH,
SH); 13C NMR (CD3OD) δ 23.13, 26.04, 27.33, 28.66, 30.46,
32.84, 33.18, 34.92, 35.09, 41.17, 177.55, 177.72; IR (film) ν
3400-3020, 2910, 2840, 2660, 2560, 1690 broad, 1400, 1265,
1220, 920; MS (GT) m/z 285 M + Na)+, 263 (M + H)+, 245 (M
- OH)+, 227 (M - 2OH - H)+. Anal. (C12H22O4S) C, H.
4-(Mer ca p tom eth yl)-1,10-d eca n ed ioic Acid (14b). Pre-
pared as 14a starting from 13b (2.346 g, 7.37 mmol). Purifica-
tion by silica gel column chromatography (chloroform/metha-
nol, 95/5) and vacuum treatment afforded 14b as a white solid
(1.075 g, 59% yield): TLC (chloroform/methanol, 9/1) Rf 0.45;
mp 53-54 °C (from column chromatography); 1H NMR (CDCl3)
δ 1.13-1.77 (m, 12H, H3-8, SH), 2.29-2.61 (m, 6H, H2,9, CH2S),
10.75 (s broad, 2H, OH); 13C NMR (CDCl3) δ 24.49, 26.04,
27.04, 27.99, 29.10, 31.35, 31.68, 33.97, 39.21, 180.05, 180.24;
MS (GT) m/z 249 (M + H)+, 231 (M - OH)+, 213 (M - 2OH -
H)+. Anal. (C11H20O4S) C, H.
6-(Mer captom eth yl)-1,12-dodecan edioic Acid (14c). Pre-
pared as 14a starting from 13c (0.662 g, 1.91 mmol). Purifica-
tion by silica gel column chromatography (chloroform/metha-
nol, 95/5) and vacuum treatment afforded 14c as a white solid
(0.346 g, 66% yield): TLC (chloroform/methanol, 9/1) Rf 0.40;
mp 56-57 °C (from column chromatography); 1H NMR (CD3-
OD) δ 1.30-1.70 (m, 15H, H3-10), 2.30 (t, J ) 6.9, 4H, H2,11),
2.48-2.58 (m, 2H, CH2S), 4.95 (s broad, 3H, OH, SH); 13C NMR
(CD3OD) δ 26.02, 26.29, 27.16, 27.33, 28.73, 30.45, 33.05, 33.22,
34.87, 34.91, 41.17, 177.65, 177.70; MS (GT) m/z 277 (M + H)+,
259 (M - OH)+, 241 (M - 2OH - H)+. Anal. (C13H24O4S) C,
H.
Dim eth yl 6,6-(1,2-Eth ylen ed ioxy)-1,11-u n d eca n ed ioa te
(17). A flask fitted with a Dean-Stark trap was charged with
a solution of ketone 11e (2.841 g, 11.00 mmol), ethylene glycol
(7.40 mL, 132.69 mmol) and p-toluenesulfonic acid (0.377 g,
1.98 mmol) in benzene (750 mL). The reaction mixture was
heated at reflux for 10 h, cooled to room temperature, washed
with 10% aqueous NaHCO3, water, and saturated NaCl, dried
over MgSO4, and concentrated in vacuo. The residue was
purified by silica gel column chromatography (heptanes/EtOAc,
7/3) to afford 17 (2.486 g, 75% yield) as a colorless oil: TLC
1
(heptanes/EtOAc, 6/4) Rf 0.48; H NMR (CDCl3) δ 1.25-1.77
(m, 12H, H3-5,7-9), 2.31 (t, J ) 6.9, 4H, H2,10), 3.67 (s, 6H,
OCH3), 3.92 (s, 4H, CH2O); 13C NMR (CDCl3) δ 23.21, 25.00,
33.86, 36.58, 51.31, 64.77, 111.16, 173.87; IR (film) ν 2930,
2860, 1740, 1420, 1355, 1230, 1185, 1160, 1060, 935; MS (NBA)
m/z 325 (M + Na)+, 303 (M + H)+, 271 (M - OCH3)+, 187 (M
- (CH2)4COOCH3)+. Anal. (C15H26O6) C, H.
Dim eth yl 5-Br om o-6,6-(1,2-eth ylen ed ioxy)-1,11-u n d e-
ca n ed ioa te (18). To a stirred solution of 17 (6.163 g, 20.38
mmol) in dry ethyl ether (35 mL) at 15 °C was slowly and
carefully added bromine (1.05 mL, 19.79 mmol). The orange-
red solution obtained was stirred for 1 h. Anhydrous Na2CO3
(4.759 g, 44.90 mmol) was then carefully added (portionwise)
and vigorously stirred for 16 h to neutralize the reaction
mixture. The white suspension was then filtered and washed
with ethyl ether. The filtrate was concentrated in vacuo, and
the resulting crude compound was purified by silica gel column
chromatography (heptanes/CH2Cl2/EtOAc, 4/5/1) to afford 18
(7.012 g, 90% yield) as a slightly yellowish oil: TLC (heptanes/
CH2Cl2/EtOAc, 4/5/1) Rf 0.40; 1H NMR (CDCl3) δ 1.32-1.43
(m, 2H, H8), 1.57-1.74 (m, 5H, H3a,4a,7a,9), 1.93-2.06 (m, 3H,
H3b,4b,7b), 2.26-2.37 (m, 4H, H2,10), 3.64 (s, 3H, OCH3), 3.65 (s,
3H, OCH3), 3.89 (dd, J ) 9.5, 1.8, 1H, H5), 3.96-4.06 (m, 4H,
CH2O); 13C NMR (CDCl3) δ 22.36, 23.63, 24.95, 32.65, 33.29,
33.71, 34.01, 51.46, 51.55, 58.98, 66,00 (2C), 110.98, 173.53,
173.92; IR (film) ν 2940, 2880, 1725, 1425, 1355, 1240, 1190,
1165, 1050, 940; MS (NBA) m/z 383 and 381 (M + H)+, 351
and 349 (M - OCH3)+, 267 and 265 (M - (CH2)4COOCH3)+,
187 (M - (CH2)4COOCH3 - Br + H)+. Anal. (C15H25BrO6) C,
H.
Dim eth yl 6,6-(1,2-Eth ylen ed ioxy)-4(E)-u n d ecen e-1,11-
d ioa te (19). To a stirred solution of bromide 18 (7.012 g, 18.39
mmol) in anhydrous DMSO (185 mL) and under argon was
added DBU (8.25 mL, 55.17 mmol). The solution was heated
at 120 °C until total disappearance of the bromide 18 on TLC
(around 20 h). The reaction was then cooled to room temper-
ature, quenched with 10% aqueous NH4Cl, and extracted with
EtOAc. The organic extract was washed with water and
saturated NaCl, dried over MgSO4, and concentrated in vacuo.
The crude product was purified by silica gel column chroma-
tography (heptanes/EtOAc, 7/3) to afford 19 (4.766 g, 86%
yield) as a colorless oil: TLC (heptanes/CH2Cl2/EtOAc, 4/5/1)
Rf 0.35; 1H NMR (CDCl3) δ 1.35-1.41 (m, 2H, H8), 1.57-1.69
(m, 4H, H7,9), 2.28 (t, J ) 7.6, 2H, H10), 2.33-2.41 (m, 4H, H2,3),
3.65 (s, 3H, OCH3), 3.66 (s, 3H, OCH3), 3.81-3.91 (m, 4H,
CH2O), 5.36 (dt, J ) 15.5, 1.3, 1H, H5), 5.75 (dt, J ) 15.4, 6.5,
1H, H4); 13C NMR (CDCl3) δ 22.92, 24.90, 26.96, 33.48, 33.90,
37.83, 51.29, 51.39, 64.30 (2C), 108.52, 129.39, 130.63, 173.12,
173.90; IR (film) ν 2930, 2875, 1720, 1655, 1425, 1355, 1230,
1180, 1155, 1025, 960; MS (NBA) m/z 323 (M + Na)+, 301 (M
+ H)+, 269 (M - OCH3)+, 185 (M - (CH2)4COOCH3)+. Anal.
(C15H24O6) C, H.
5-(Mer ca p tom eth yl)-1,10-d eca n ed ioic Acid (14d ). Pre-
pared as 14a starting from 13d (1.353 g, 4.25 mmol). Puri-
fication by silica gel column chromatography (chloroform/
methanol, 95/5) and vacuum treatment afforded 14d as a white
solid (0.900 g, 85% yield): TLC (chloroform/methanol, 9/1) Rf
1
0.50; mp 60-62 °C (from column chromatography); H NMR
(CDCl3) δ 1.18 (t, J ) 8.0, 1H, SH), 1.30-1.45 (m, 6H, H4,6,7),
1.48-1.56 (m, 1H, H5), 1.58-1.65 (m, 4H, H3,8), 2.34 (t, J )
7.3, 2H, H2 or 9), 2.35 (t, J ) 7.3, 2H, H2 or 9), 2.51 (dd, J )
8.0, 5.5, 2H, CH2S), 10.44 (s broad, 2H, OH); 13C NMR (CDCl3)
δ 21.62, 24.76, 25.88, 28.22, 31.48, 31.70, 33.92, 34.13, 39.67,
179.67; IR (KBr) ν 3400 broad, 3040 broad, 2920, 2840, 1695,
1450, 1420, 1395, 1285, 1230, 1180, 920 broad; MS (NBA) m/z
271 (M + Na)+, 249 (M + H)+, 231 (M - OH)+, 213 (M - 2OH
- H)+. Anal. (C11H20O4S) C, H,O.
6-(Mer captom eth yl)-1,11-u n decan edioic Acid (14e). Pre-
pared as 14a starting from 13e (0.475 g, 1.429 mmol).
Purification by silica gel column chromatography (chloroform/
methanol, 95/5) and vacuum treatment afforded 14e as a white
solid (0.285 g, 76% yield): TLC (chloroform/methanol, 9/1) Rf
1
0.48; H NMR (CDCl3) δ 1.18 (t, J ) 8.0, 1H, SH), 1.24-1.45
(m, 8H, H4,5,7,8), 1.50-1.55 (m, 1H, H6), 1.57-1.66 (m, 4H, H3,9),
2.35 (t, J ) 7.2, 4H, H2,10), 2.50 (dd, J ) 8.0, 5.7, 2H, CH2S),
10.67 (s broad, 2H, OH); 13C NMR (CDCl3) δ 24.78, 25.88,
28.34, 31.72, 34.00, 39.62, 180.32; IR (film) ν 3400-3000, 2920,
2840, 2660, 1690 broad, 1450-1400, 1270 broad, 925 broad;
MS (NBA) m/z 285 (M + Na)+, 263 (M + H)+, 245 (M - OH)+,
227 (M - 2OH - H)+. Anal. (C12H22O4S) C, H.
5-(Mer captom eth yl)-1,12-dodecan edioic Acid (14f). Pre-
pared as 14a starting from 13f (0.536 g, 1.487 mmol).
Purification by silica gel column chromatography (chloroform/
methanol, 95/5) and vacuum treatment afforded 14f as a white
solid (0.302 g, 74% yield): TLC (chloroform/methanol, 9/1) Rf
Dim eth yl 6-Oxo-4(E)-u n d ecen e-1,11-d ioa te (20). To a
stirred suspension of silica gel (63-200 µm, 8.0 g) in CH2Cl2
(16 mL) was added a mixture of TFA (0.63 mL, 8.23 mmol)
and water (0.63 mL). The suspension was vigorously stirred
for 10 min at room temperature, then a solution of 19 (1.658
g, 5.52 mmol) in CH2Cl2 (5 mL) was added dropwise, and the
mixture stirred for an additional 2 h. The reaction mixture
was filtered and the silica gel washed with ethyl ether (4 ×
30 mL). The organic filtrate was then washed with 10%
aqueous NaHCO3, water, and saturated NaCl, dried over
MgSO4, and concentrated in vacuo. The crude product was
purified by silica gel column chromatography (heptanes/ethyl
1
0.45; mp 44-45 °C (from column chromatography); H NMR
(CD3OD) δ 1.28-1.73 (m, 15H, H3-10), 2.29 (t, J ) 6.8, 4H,
H
2,11), 2.49-2.60 (m, 2H, CH2S), 4.98 (s broad, 3H, OH, SH);
13C NMR (CD3OD) δ 23.13, 26.06, 27.47, 28.69, 30.16, 30.63,
32.85, 33.27, 34.95, 35.10, 41.19, 177.55, 177.74; IR (film) ν
3300-3000, 2900, 2820, 2640, 2240, 2040, 1685 broad, 1390,
1220, 1040, 910 broad; MS (GT) m/z 299 (M + Na)+, 277 (M +
H)+, 259 (M - OH)+, 241 (M - 2OH - H)+. Anal. (C13H24O4S)
C, H.

Nonpeptidic and Peptidase-Stable GSH Analogues
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13 2287
ether, 5/5) to afford 20 (1.272 g, 90% yield) as a colorless oil:
TLC (heptanes/EtOAc, 4/6) Rf 0.40; 1H NMR (CDCl3) δ 1.58-
1.63 (m, 4H, H8,9), 2.22-2.30 (m, 2H, H10), 2.44-2.52 (m, 6H,
H2,3,7), 3.62 (s, 3H, OCH3), 3.65 (s, 3H, OCH3), 6.08 (dt, J )
15.9, 1.5, 1H, H5), 6.76 (dt, J ) 15.9, 6.4, 1H, H4); 13C NMR
(CDCl3) δ 23.47, 24.49, 27.36, 32.33, 33.78, 39.73, 51.32, 51.61,
130.81, 144.29, 172.50, 173.65, 199.45; IR (film) ν 2950, 2870,
1725, 1685, 1660, 1620, 1430, 1360, 1245, 1190, 1160, 1040,
965, 720; MS (NBA) m/z 279 (M + Na)+, 257 (M + H)+, 225
(M - OCH3)+. Anal. (C13H20O5) C, H; C: calcd, 60.92; found,
60.10.
purified by silica gel column chromatography (chloroform/
methanol, 9/1 to 85/15) to give pure alcohol 23 as a colorless
oil which was placed under vacuum for 24 h to eliminate trace
amounts of solvents (0.0400 g, 73% yield): TLC (chloroform/
1
methanol, 85/15) Rf 0.25; H NMR (CD3OD) δ 1.13-1.62 (m,
6H, H7-9), 2.21-2.38 (m, 7H, H2,3,6,10), 3.41 (d, J ) 6.5, 2H,
CH2OH), 4.88 (s broad, 3H, OH), 5.12-5.60 (m, 2H, H4,5); 13
C
NMR (CD3OD) δ 28.65, 30.17, 31.66, 34.34, 37.42, 37.57, 49.18,
69.42, 133.95, 136.38, 179.58, 180.23; MS (GT) m/z 267 (M +
Na)+, 245 (M + H)+, 227 (M - OH)+, 209 (M - 2OH - H)+,
191 (M - 3OH - 2H)+. Anal. (C12H20O5‚0.5H2O) C, H.
Dim eth yl 6-[(Acetylth io)m eth yl]-4(E)-u n d ecen e-1,11-
d ioa te (24). To a solution of triphenylphosphine (0.484 g, 1.84
mmol) in freshly distilled THF (4.6 mL) at 0 °C was added
dropwise diisopropyl azodicarboxylate (DIAD; 0.36 mL, 1.83
mmol). The mixture was stirred at 0 °C for 30 min, and a
white solid precipitated out. To this suspension, compound
22 (0.251 g, 0.922 mmol) dissolved in dry THF (2.30 mL) was
added, followed by thiolacetic acid (0.13 mL, 1.83 mmol). The
reaction was stirred at 0 °C for 1 h and at room temperature
for an additional 1 h, diluted, and extracted with ethyl ether.
The organic extract was washed with water and saturated
NaCl, dried over MgSO4, and concentrated. The crude mate-
rial was purified by two column chromatographies on silica
gel (heptanes/ethyl ether, 6/4, and petroleum spirit/ethyl ether,
8/2) to give pure 24 as a yellowish oil (0.251 g, 93% yield):
TLC (heptanes/ethyl ether, 5/5) Rf 0.45; 1H NMR (CDCl3) δ
1.16-1.43 (m, 4H, H7,8), 1.50-1.61 (m, 2H, H9), 2.01-2.12 (m,
1H, H6), 2.20-2.35 (m, 6H, H2,3,10), 2.26 (s, 3H, CH3CO), 2.74
(dd, J ) 13.3, 7.9, 1H, CH2S), 2.87 (dd, J ) 13.3, 5.9, 1H,
CH2S), 3.61 (s, 3H, OCH3), 3.62 (s, 3H, OCH3), 5.14 (dd, J )
15.3, 8.7, 1H, H5), 5.38 (td, J ) 15.3, 6.3, 1H, H4); 13C NMR
(CDCl3) δ 24.76, 26.52, 27.72, 30.53, 33.78, 33.88, 33.92, 34.26,
42.42, 51.38, 51.43, 129.96, 133.26, 173.35, 173.98, 195.56; IR
(film) ν 2930, 2840, 1720, 1680, 1425, 1340, 1240, 1180, 1160,
1120, 1095, 955, 610; MS (GT) m/z 353 (M + Na)+, 331 (M +
H)+, 289 (M - CH3CO + 2H)+, 257 (M - OCH3 - CH3CO +
H)+, 243, 225 (M - 2OCH3 - CH3CO)+. Anal. (C16H26O5S)
C, H.
Dim eth yl 6-Meth ylen e-4(E)-u n d ecen e-1,11-d ioa te (21).
A -10 °C suspension of Ph3PCH3Br (1.842 g, 5.16 mmol) in
freshly distilled THF (15 mL) under argon was treated with
n-BuLi (2.0 mL, 2.5 M in hexanes, 5.00 mmol), stirred up to
room temperature for 30 min, and recooled at -10 °C. To this
orange suspension was added a solution of 20 (1.152 g, 4.49
mmol) in freshly distilled THF (4 mL) dropwise. The reaction
mixture was stirred at -10 °C for 10 min and then at room
temperature for 1 h. The reaction was quenched with 10%
aqueous NH4Cl (10 mL), ethyl ether (30 mL) was added, and
the mixture was extracted twice with ethyl ether. The
combined organic phase was washed with water and saturated
NaCl, dried over MgSO4, and concentrated in vacuo. The
crude product, containing the formed triphenylphosphine
oxide, was taken up in ethyl ether (20 mL), filtered, and
washed with ethyl ether. The collected filtrate was concen-
trated in vacuo, and the residue was purified by silica gel
column chromatography (heptanes/ethyl ether, 75/25) to afford
21 (0.709 g, 62% yield) as a colorless liquid: TLC (heptanes/
1
ethyl ether, 75/25) Rf 0.32; H NMR (CDCl3) δ 1.41-1.50 (m,
2H, H8), 1.57-1.65 (m, 2H, H9), 2.12 (t, J ) 7.5, 2H, H7), 2.27
(t, J ) 7.3, 2H, H10), 2.36-2.37 (m, 4H, H2,3), 3.61 (s, 3H,
OCH3), 3.62 (s, 3H, OCH3), 4.84 (d, J ) 15.8, 2H, CH2d), 5.63
(td, J ) 15.8, 6.6, 1H, H4), 6.02 (d, J ) 15.8, 1H, H5); 13C NMR
(CDCl3) δ 24.63, 27.42, 27.91, 31.54, 33.67, 33.73, 51.24, 51.33,
114.02, 127.35, 132.94, 145.24, 173.20, 173.85; IR (film) ν 3070,
2930, 2850, 1720, 1600, 1420, 1345, 1240, 1180, 1155, 955, 875;
MS (NBA) m/z 277 (M + Na)+, 255 (M + H)+, 223 (M -
OCH3)+, 191 (M - 2OCH3 - H)+. Anal. (C14H22O4) C, H.
6-(Mer ca p t om et h yl)-4(E)-u n d ecen e-1,11-d ioa t e (25).
Prepared as 14a starting from 24 (0.247 g, 0.748 mmol).
Purification by silica gel column chromatography (chloroform/
methanol, 95/5) and vacuum treatment afforded 27 as a white
solid (0.125 g, 64% yield): TLC (chloroform/methanol, 9/1) Rf
Dim eth yl 6-(Hyd r oxym eth yl)-4(E)-u n d ecen e-1,11-d io-
a te (22). To a stirred solution of 9-BBN-H (1.006 g, 4.12
mmol) in freshly distilled THF (7 mL) at room temperature
and under argon was added dropwise a solution of diene 21
(0.698 g, 2.75 mmol) in freshly distilled THF (2 mL). The
reaction mixture was stirred for 2 h, then cooled to -0 °C, and
hydrolyzed with the careful addition of NaOH (1.40 mL, 3 M
in water, 4.20 mmol) followed by H2O2 (1.40 mL, 30 wt % in
water). The reaction was stirred at room temperature over-
night and diluted with ethyl ether (20 mL), and 10% aqueous
NaHCO3 (6 mL) was added. The layers were separated, and
the water phase was extracted with ethyl ether. The conbined
organic extract was washed with 10% aqueous NaHCO3,
water, and saturated NaCl, dried over MgSO4, and concen-
trated in vacuo. The residue was purified by silica gel column
chromatography (heptanes/ethyl ether, 3/7) to give 22 (0.439
g, 59% yield) as a colorless oil: TLC (heptanes/EtOAc, 5/5) Rf
1
0.38; H NMR (CDCl3) δ 1.15-1.63 (m, 7H, H7,8,9, SH), 2.00-
2.12 (m, 1H, H6), 2.22-2.45 (m, 8H, H2,3,10, CH2S), 5.13 (dd, J
) 15.3, 8.8, 1H, H5), 5.43 (td, J ) 15.3, 6.3, 1H, H4), 10.29 (s
broad, 2H, OH); 13C NMR (CDCl3) δ 24.43, 26.35, 27.48, 29.68,
33.30, 33.89, 33.94, 45.67, 130.17, 133.35, 179.37, 180.13; MS
(GT) m/z 261 (M + H)+, 219. Anal. (C12H20O4S) C, H.
Biologica l Meth od s. 1. GST Exp r ession . The recom-
binant GST was prepared as described by Smith and Corco-
zan28 using an Escherichia coli XL1 blue strain transformed
with the pGEX vector (Pharmacia Biotech).12 Briefly, 5 L of
TB/ampicillin medium in a 7.5-L tabletop fermentor was
inoculated with an overnight starter culture. Expression of
the recombinant protein was induced by adding IPTG to a final
concentration of 0.1 mM. Induction was allowed to proceed
for 2 h. The cells were then harvested by centrifugation (4000g
for 30 min). After lysis of the bacteria, the recombinant GST
protein was purified on a GSH-agarose (Sigma) column. The
recovered protein was then desalted on a Sephadex G-50
column and freeze-dried.
1
0.42; H NMR (CDCl3) δ 1.10-1.67 (m, 6H, H7-9), 2.02-2.40
(m, 8H, H2,3,6,10, OH), 3.20-3.44 (m, 2H, CH2OH), 3.60 (s, 6H,
OCH3), 5.14 (dd, J ) 15.3, 8.4, 1H, H5), 5.48 (td, J ) 15.4, 5.9,
1H, H4); 13C NMR (CDCl3) δ 24.76, 26.41, 27.86, 30.38, 33.79
(2C), 45.46, 51.30, 51.38, 65.66, 131.06, 132.63, 173.46, 174.01;
IR (film) ν 3600-3240, 2930, 2860, 1725, 1430, 1360, 1245,
1195, 1160, 1040, 960; MS (GT) m/z 273 (M + H)+, 255 (M -
OH)+, 241 (M - OCH3)+, 223 (M - OH - OCH3 - H)+.
2. P r otein Con cen tr a tion . The protein concentration
used throughout this work was inferred from UV absorbance
measurements at 276 nm (Cary 118 spectrophotometer) in the
absence of aggregation effects (as determined in the 300-350-
nm range). Molar absorptivities at 276 nm of the protein used
in this work were determined by the procedure of Gill and von
6-(Hyd r oxym eth yl)-4(E)-u n d ecen e-1,11-d ioic Acid (23).
Compound 22 (0.0609 g, 0.224 mmol) was dissolved in a
mixture of ethanol (0.5 mL) and KOH solution (0.5 mL, 2 M
in water, 1.0 mmol). The mixture was stirred at room
temperature for 6 h, acidified with 1 N HCl (pH around 1),
and extracted with EtOAc. Small quantities of saturated NaCl
solution were added to resolve emulsions. The combined
organic extracts were washed with saturated NaCl, dried over
MgSO4, and concentrated in vacuo. The crude product was
Hippel (1989) giving 35 050 L mol-1 cm-1
.
3. Bin d in g Assa ys. A protein affinity chromatography
method was used to evaluate binding of the GSH analogues
to the recombinant GST protein. The recombinant GST was
dialyzed in a PBS buffer (137 mM NaCl, 2.7 mM KCl, 4.3 mM

2288 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 13
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Na2HPO4, 1.4 mM KH2PO4, pH 7.3) and bound to a glu-
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dissociation plots obtained were used to determine the IC50
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Ack n ow led gm en t. This work was supported by the
Centre National de la Recherche Scientifique of France
(CNRS). The authors are grateful to Dr. J -P. Vidal for
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