An asymmetric synthesis of (+)-grandisol, a constituent of the aggregation pheromone of the cotton boll weevil, via a kinetic resolution

Article abstract of DOI:10.1021/jo000853+

A novel approach to the asymmetric synthesis of (+)-grandisol, (1R,2S)-isopropenyl-1-methylcyclobutaneethanol, involves the use of catalytic kinetic resolution of a primary allylic alcohol, [(1RS,5SR)-5-methylbicyclo[3.2.0]hept-2-en-2-yl] methanol. The allylic alcohol is prepared in four steps from simple achiral materials involving the use of a modified Shapiro reaction. The resolved alcohol (95% ee) is then reduced in two steps to the corresponding methyl alkene, (1S,5R)-2,5-dimethylbicyclo[3.2.0]hept-2-ene. This alkene is converted to (+)-grandisol (95% ee), in three steps, by modified literature procedures.

Full text of DOI:10.1021/jo000853+

J . Org. Chem. 2000, 65, 7839-7846
7839
An Asym m etr ic Syn th esis of (+)-Gr a n d isol, a Con stitu en t of th e
Aggr ega tion P h er om on e of th e Cotton Boll Weevil, via a Kin etic
Resolu tion
David P. G. Hamon and Kellie L. Tuck*
The Department of Chemistry, The University of Adelaide, S.A. 5005, Australia
kellie.tuck@unisa.edu.au
Received J une 3, 2000
A novel approach to the asymmetric synthesis of (+)-grandisol, (1R,2S)-isopropenyl-1-methylcy-
clobutaneethanol, involves the use of catalytic kinetic resolution of a primary allylic alcohol,
[(1RS,5SR)-5-methylbicyclo[3.2.0]hept-2-en-2-yl] methanol. The allylic alcohol is prepared in four
steps from simple achiral materials involving the use of a modified Shapiro reaction. The resolved
alcohol (95% ee) is then reduced in two steps to the corresponding methyl alkene, (1S,5R)-2,5-
dimethylbicyclo[3.2.0]hept-2-ene. This alkene is converted to (+)-grandisol (95% ee), in three steps,
by modified literature procedures.
The ability to prepare enantiomerically enriched or-
ganic compounds by the use of catalytic amounts of
enantiopure material is of paramount importance in
asymmetric synthesis. Furthermore, the continual de-
velopment of new techniques and strategies means that
older synthetic problems can be solved in new and better
ways. One such molecule which has been used often in
this context is (+)-grandisol 1. Grandisol 1 is the principle
component of the aggregation pheromone of the male
cotton boll weevil, Anthonomus grandis Boheman.1 It has
been a popular molecule for synthesis, both as a synthetic
challenge or as a tool to investigate the properties of the
naturally occurring pheromone. The cotton boll weevil
is a serious pest of cotton crops in the United States and
Central America.1 There are a number of ways of making
the required enantiomer of grandisol.2,3 Few of these are
by asymmetric synthesis, and those that are, mostly
employ a stoichiometric amount of a chiral auxiliary to
induce asymmetry.4 All require the extensive separation
of diastereomers. The construction of the four-membered
ring, in an enantioselective manner from achiral starting
materials, would be the ideal approach to a catalytic
asymmetric synthesis of grandisol, but to date, experi-
ments with that approach in mind have not been very
successful.5 Although less satisfactory in concept, but
perhaps nevertheless more successful in practice, is to
consider a kinetic resolution of a preformed cyclobutane
intermediate. If the intermediate is efficiently synthe-
sized, if the kinetic resolution is effective and catalytic
in resolving agent, and if the synthesis can be completed
without the need for separating diastereomers, then
overall the process may be a useful endeavor. Further-
more, there is no doubt that such pursuits can be
important in pedagogy for the insights they provide. With
these ideas in mind we set out to explore this approach,
and herein we describe the details of a new asymmetric
synthesis of grandisol, which was reported earlier as a
preliminary communication,6 whereby grandisol 1 can be
synthesized in 8% overall yield and 95% ee in 10 steps
from achiral materials. This synthesis uses a kinetic
resolution of a primary allylic alcohol by a Sharpless
asymmetric epoxidation reaction as the source of chiral-
ity. To our knowledge this is the first time such a
resolution has been used in the synthesis of a natural
product. As far as we are aware this is the shortest route
for the formation of optically active grandisol from achiral
materials, and it employs only a catalytic amount of
enantiopure reagents.
Syntheses of racemic grandisol 1 of particular perti-
nence to our route to the optically active pheromone are
those of Rosini.7-9 It was recognized that cis-(()-2,5-
dimethylbicyclo[3.2.0]hept-2-ene 2 constitutes a key in-
termediate for an efficient synthesis of the natural
product because (()-grandisol 1 could be formed in three
steps from this bicyclic alkene 2.8 We recognized that
enantiomerically enriched alkene 2 should be available
from the optically active allylic alcohol 3 and that, in
principle, the nonracemic alcohol could be obtained from
a kinetic resolution of the primary allylic alcohol 3 by
the Sharpless asymmetric epoxidation reaction. The use
of the Sharpless asymmetric epoxidation reaction is well-
known for the kinetic resolution of secondary alcohols
where the stereogenic center bears the hydroxyl group.
However, there are few reported kinetic resolutions of
primary allylic alcohols by this method, and most of these
do not yield the starting material with high enantiopurity
in reasonable yield.10 Inspection of a molecular model
* As Dr. D. P. G. Hamon has retired, any correspondence concerning
this paper should be addressed to Dr. K. L. Tuck.
(1) Tumlinson, J . H.; Gueldner, R. C.; Hardee, D. D.; Thompson, A.
C.; Hedin, P. A.; Minyard, J . P. J . Org. Chem. 1971, 36, 2616-21.
(2) Mori, K. In The Total Synthesis of Natural Products; ApSimon,
J ., Eds.; J ohn Wiley: New York, 1981; Vol. 4, pp 120-2, 488-93.
(3) Mori, K. In The Total Synthesis of Natural Products; ApSimon,
J ., Eds.; J ohn Wiley: New York, 1992; Vol. 9, pp 303-12.
(4) A catalytic Sharpless AE reaction has been used to prepare (+)-
grandisol as a minor product. Martin, T., Rodriguez, C. M., Martin, V.
S. Tetrahedron Asymmetry 1995, 6, 1151-64.
(6) Hamon, D. G. H., Tuck K. L. Tetrahedron Lett. 1999, 40, 7569-
72.
(7) Rosini, G.; Salomoni, A.; Squarcia, F. Synthesis 1979, 942-44.
(8) Rosini, G.; Marotta, E.; Petrini, M.; Ballini, R. Tetrahedron 1985,
41, 4633-38.
(9) Confalonieri, G.; Marotta, E.; Rama, F.; Righi, P.; Rosini, G.;
Serra, R.; Venturelli, F.; Tetrahedron 1994, 50, 10, 3235-3250.
(5) Langer, K.; Mattay, J . J . Org. Chem. 1995, 60, 7256-66.
10.1021/jo000853+ CCC: $19.00 © 2000 American Chemical Society
Published on Web 10/21/2000

7840 J . Org. Chem., Vol. 65, No. 23, 2000
Hamon and Tuck
reactions of cyclohexenones with ethylene.15,16 Therefore,
it was of interest to see if similar chemistry with the
cyclopentenone pertained.
Exchange of the acidic protons, in the bicyclic ketone
4, by deuterium (D2O, -OD) gave the deuterated com-
pound from which it could be determined which proton
1
resonances, in the H NMR spectrum, were due to those
1
adjacent to the carbonyl group. The H NMR spectrum
of the bicyclic ketone 4 at 600 MHz also clarified the
situation somewhat. By the use of HETCOR and COSY
spectra, the 1H NMR spectrum of the bicyclic ketone
could be fully assigned (see Experimental Section and
Supporting Information). In particular the peak at δ 2.25
was shown to be due to one proton of the methylene group
adjacent to the carbonyl group. The 13C NMR spectrum
showed only eight resonances, and there was only one
F igu r e 1. The proposed kinetic resolution of the allylic alcohol
3 by the Sharpless asymmetric epoxidation reaction.
reveals that the allylic alcohol 3 has an open accessible
convex face and also a much more hindered concave face.
From the Sharpless mnemonic, L-(+)-diisopropyl tartrate
(L-(+)-DIPT) should attack preferentially one enantiomer
of the racemate, as shown (Figure 1), and leave the other
enantiomer of the allylic alcohol in high enantiomeric
purity. It was of interest therefore to see if the Sharpless
asymmetric epoxidation reaction could be used effectively
for a kinetic resolution in a molecule where the chiral
center is remote from the hydroxyl.10,11 However, since a
kinetic resolution must necessarily waste at least half
of the material it was necessary to prepare the racemic
key intermediate in as efficient a route as possible.
Th e Syn th esis of th e Ra cem ic Key Allylic Alcoh ol.
Initially it was thought that this key intermediate might
be formed via an epoxide 5 or 6 in three steps from the
ketone, 3-methyl-2-cyclopentenone. It is known that the
bicyclic ketone 4 is available in high yield via a [2 + 2]
photocycloaddition reaction on 3-methyl-2-cyclopenten-
one.12 Addition of sulfoxonium or sulfonium ylides to the
ketone should give the epoxide 5 and/or 6. Treatment of
the epoxide 5 and/or 6 with a nonnucleophilic amide base
might then give the required racemic allylic alcohol 3.
Commercially available13 3-methyl-2-cyclopentenone
was contaminated with up to 5% acetonyl acetone (as
determined by 1H and 13C NMR spectra), and this caused
complications with the purification of the bicyclic ketone
4. This contamination was avoided by the synthesis of
3-methyl-2-cyclopentenone from acetonyl acetone by re-
action with aqueous potassium hydroxide.14
1
sharp signal for a methyl group in the H NMR. Conse-
quently, only one isomer of the bicyclic ketone 4 had
formed directly, and it was the previously reported
thermodynamically more stable cis-isomer.12
Formation of two epoxides was possible upon reaction
of the ketone 4 with either dimethylsulfoxonium meth-
ylide ((CH3)3OS+I-) or dimethylsulfonium methylide
((CH3)3S+I-)). From previous work,17 it is known that
addition of the stabilized ylide, dimethylsulfoxonium
methylide, to a ketone is reversible, whereas addition of
the nonstabilized ylide, dimethylsulfonium methylide, is
irreversible. Therefore, it is expected that the two re-
agents would give different ratios of products. In the case
of the stabilized ylide, the ratio of the epoxides obtained
should be dependent on the relative energies of the
transition states of the second step. However, when the
first step in the reaction is nonreversible, as in the case
with the nonstabilized ylide, the product formed should
reflect the ease of approach of the reagent. Since the
concave face is subject to greater steric hindrance than
the convex face, this should favor formation of the epoxide
shown (Figure 2).
Reaction of the bicyclic ketone 4 with dimethylsulfoxo-
nium methylide (reversible addition) gave two epoxides
5 and 6 in the ratio 4.3:5.7. Reaction of the bicyclic ketone
with dimethylsulfonium methylide (irreversible addition)
gave only one epoxide 5.
The photochemical [2 + 2] cycloaddition reaction of
3-methyl-2-cyclpentenone with ethylene then gave the
To confirm the stereochemistry of the epoxides, they
were formed in a different way. A Wittig reaction between
methylenetriphenylphosphorane and the bicyclic ketone
4 gave the known7 volatile alkene 7. Addition of mCPBA
to this alkene 7 in a buffered solution gave the two
epoxides 5 and 6. In this kinetically controlled reaction,
attack should come preferentially from the convex face
to give the epoxide 6 with the oxygen cis to the methyl
group as the major product. At -5 °C the two epoxides 5
and 6 are formed in the ratio 2:8, at -12 °C a 1:9 ratio of
epoxides resulted. The major product formed was the
same as the major product formed from the stabilized
ylide reaction i.e., 6, whereas the minor product was the
same as the product from the reaction of the nonstabi-
lized ylide, i.e., 5.
1
bicyclic ketone 4. Comparison of the H NMR signals for
this product corresponded to the literature values quoted
for a spectrum obtained at a lower field strength. Due to
the complexity of the signals at 300 MHz, it was not clear
if the product was the desired cis-isomer or a mixture of
isomers. In particular the lower peak assignable to a CH
next to a carbonyl appeared as a doublet of doublet of
doublets. This was not consistent with the methine
proton in 4 but might correspond to overlapping signals
of this methine proton if both the cis and trans com-
pounds were present in equal amounts. In syntheses of
caryophyllene and caryophyllene alcohol a mixture of cis
and trans isomers are formed during [2 + 2] cycloaddition
(10) Principles of Asymmetric Synthesis; Gawlwy, R. E., Aube´, J .,
Eds.; Elselvier Science: New York, 1996; p 331.
There are numerous examples of base-induced isomer-
ization of epoxides to give allylic alcohols,18 but there are
(11) A primary alcohol exhibiting planar chirality has been resolved
in this manner and used in a synthesis of betweenanenes. Marshall,
J . A.; Flynn, K. E. J . Am. Chem. Soc. 1983, 105, 3360-62.
(12) Cargill, R. L.; Dalton, J . R.; Morton, G. H.; Caldwell, W. E. Org.
Synth. 1984, 62, 118-124.
(13) Sigma Aldrich Chemical Co., Sydney, Australia.
(14) Bagnell, L.; Bliese, M.; Cablewski, T.; Strauss, C. R.; Tsanakt-
sidis, J . Aust. J . Chem. 1997, 50, 921-25.
(15) Corey, E. J .; Mitra, R. B.; Uda, H. J . Am. Chem. Soc. 1964, 86,
485-92.
(16) Corey, E. J .; Nozoe, S. J . Am. Chem. Soc. 1965, 87, 5733-35.
(17) J ohnson, C. R.; Schroeck, C. W.; Shankin J . R. J . Am. Chem.
Soc. 1973, 95, 7424-31.

Asymmetric Synthesis of (+)-Grandisol
J . Org. Chem., Vol. 65, No. 23, 2000 7841
F igu r e 2. Reaction of the stabilized and nonstabilized ylides with the bicyclic ketone 4.
Sch em e 1a
few examples of this reaction on terminal epoxides.
Nevertheless, the reaction of â-pinene oxide with lithium
diethylamide in ether to give, in 81% yield, the corre-
sponding allylic alcohol, provides a precedent.19
Reaction of a mixture of the epoxides 5 and 6 with
several nonnucleophilic amide bases (LiNEt2; LiNEt2,
HMPA; LDA, HMPA) gave very poor yields of the desired
allylic alcohol 3 with a 2% yield the highest obtained,
most of the product was intractable material. More
extensive experiments on a model epoxide 8 (nBuLi, DBU,
and tBuOK), did not give the expected allylic alcohol. An
alternative approach was reaction of a mixture of ep-
oxides 5 and 6 with the reagent trimethylsilyl trifluo-
romethanesulfonate (TMSOTf).20,21 Several different varia-
a
Conditions: (a) NH2NHTs, MeOH. (b) (1) nBuLi, TMEDA. (2)
CH2O. (3) H3O+. (c) (1) nBuLi, TMEDA. (2) DMF. (3) H3O+. (d)
NaBH4/CeCl3.
tions of this reaction were explored in which the solvent
and the temperature were changed. However, the best
yield of the allylic alcohol 3 obtained was only 27%, and
this was not sufficiently high for the preparation of an
intermediate in a multistep synthesis.
or formaldehyde as the electrophile to produce R,â-
unsaturated aldehydes or allylic alcohols, respectively.
The ketone 4 was converted to the tosyl hydrazone 9
in a 90% yield (Scheme 1). Treatment of the tosyl
hydrazone 9 with 3 equiv of nBuLi, followed by reaction
of the intermediate alkenyl anion with gaseous formal-
dehyde, gave the required allylic alcohol 3 in only a 5%
yield. Better results are achieved when the electrophile
is DMF. The reaction proceeds to give the crude unsatur-
ated aldehyde 10 in a good yield after workup, if strict
adherence to the conditions carefully detailed in the
Experimental Section are followed. The crude aldehyde
10 is reduced immediately with sodium borohydride and
ceric chloride, and the desired allylic alcohol 3 is obtained
in a 75% overall yield from the bicyclic ketone 4. Thus, a
high yielding four-step synthesis of the key allylic alcohol
3 from 3-methylcyclopentenone is available, without the
need for chromatographic purification.
A different approach to the synthesis of the allylic
alcohol 3 was pursued. There are examples in the
literature of the use of modified Shapiro reactions22-27
where the vinyl anion generated reacts with either DMF
Th e Kin etic Resolu tion . Sharpless has noted that
the kinetic resolution of allylic alcohols by the AE
reaction is adversely affected by the presence of water,
and he has published extensive experimental details for
the procedures.28 The reaction reported here is extremely
sensitive to the presence of water, and we found it
necessary to practice the AE reaction first on the achiral
model compound 11, and this led to the discovery of an
interesting secondary reaction. The allylic alcohol 11 was
prepared from the corresponding R,â-unsaturated ester
by a LiAlH4 reduction.29,30
(18) For a review on base-induced isomerization reactions, see:
Crandall, J . K.; Apparu, M. Org. React. 1983, 29, 345-441.
(19) Hill, R. K.; Morgan, J . W.; Shetty, R. V.; Synerholm, M. E. J .
Am. Chem. Soc. 1974, 96, 4201-06. Since this work was completed, a
further example has appeared: Leonard, J .; Bennett, L.; Mahmood,
A. Tetrahedron Lett. 1999, 40, 3965-68.
(20) Murata, S.; Suzuki, M.; Noyori, R. J . Am. Chem. Soc. 1979,
101, 2738-39.
(21) Murata, S.; Suzuki, M.; Noyori, R., J . Tetrahedron 1981, 37,
3899-3910.
(22) Shapiro, R. H.; Heath, M. J . J . Am. Chem. Soc. 1967, 89, 5734-
35.
(23) Adlington, R. M.; Barrett, A. G. M. Acc. Chem. Res. 1983, 16,
55-59.
(24) Chamberlin, A. R.; Bond, F. T. Synthesis 1979, 44-45.
(25) Stemke, J . E.; Chamberlin, A. R.; Bond, F. T. Tetrahedron Lett.
1976, 34, 2947-50.
(26) Shapiro, R. H.; Lipton, M. F.; Kolonko, K. J .; Buswell, R. L.;
Capuano, L. A. Tetrahedron Lett. 1975, 1811-14.
(27) Traas, P. C.; Boelens, H.; Takken, H. J . Tetrahedron Lett. 1976,
26, 2287-88.
The general literature procedure28 with L-(+)-DIPT was
followed but with the following adaptations. When the
(28) Gao, Y.; Hanson, R. A.; Klunder, J . M.; Ko, S. Y.; Masamune,
H.; Sharpless, K. B. J . Am. Chem. Soc. 1987, 109, 5765-80.
(29) Wadsworth, W. S Org. React. 1977, 25, 73-253.
(30) Ellis, M. K.; Golding, B. T. Org. Synth. 1984, 63, 140-46.

7842 J . Org. Chem., Vol. 65, No. 23, 2000
Hamon and Tuck
Ta ble 1. Kin etic Resolu tion Resu lts a t Va r iou s
Tem p er a tu r es
aliquots are removed and quenched with ferrous sulfate
and citric acid as described, two things are important.
First, it is better to use CH2Cl2 as the solvent, as the
allylic alcohol 11 is not extracted efficiently with ether.
Second, the product should be extracted immediately, as
the epoxy alcohol 12 undergoes a slow reaction with
ferrous sulfate and citric acid (but not citric acid alone).
The product of this rearrangement is the epoxy alkene
13, which arises presumably from a Lewis-acid-catalyzed
Payne rearrangement31 followed by dehydration of the
resultant tertiary alcohol.32
temp
(°C)
enantiomeric
% of 3
% conversion
excess, %a
recoveredc
-20
-40
-60
80
60
55
>98b
95
90
18
30
34
a
The enantiomeric excess of the allylic alcohol was determined
b
by conversion to the corresponding Mosher esters. Only one
enantiomer detected by 1H NMR spectroscopy. c Refers to the yield
of 3 obtained after purification by flash chromatography.
Sch em e 2a
Even after the epoxidation reaction of the allylic alcohol
11 had been mastered, the kinetic resolution reaction of
the key intermediate 3 still gave inconsistent results. It
was found necessary to introduce a slight modification
to the reported standard procedure to ensure reproducible
removal of all water. It was also found that it is better
to limit the amount of tert-butyl hydroperoxide added to
the reaction vessel and allow the reaction to proceed for
an adequate length of time, as this avoids the risk that
water can be introduced when the progress of the reaction
is followed by GC. A small portion of the reaction mixture
is worked up in the described manner to determine the
exact percentage of the allylic alcohol remaining.
Before the asymmetric epoxidation reaction was at-
tempted on the key allylic alcohol 3, a method was needed
for the determination of the enantiomeric enrichment of
this key intermediate. This was not straightforward. No
useful separation was seen with NMR experiments on
the alcohol or derived acetate with the chiral shift reagent
Eu(hfc)3. The diastereomeric urethanes derived from (S)-
(-)-R-methylbenzyl isocyanate gave no useful separation
by either chromatography or NMR. Partial, but incom-
plete separation, of the alcohol enantiomers was found
on chiral GC.33 Eventually it was discovered that an
a
Conditions: (a) (MeSO2)2O, Et3N, CH2Cl2. (b) LiAlH4, THF.
(c) NaIO4, RuCl3‚3H2O, tBuOH, H2O. (d) Ph3PCH2I, n-BuLi, THF.
(e) LiAlH4, THF.
of the enantiomers confirmed the interpretation. (Repro-
duction of these regions and those for the methoxy
resonances in the 1H NMR spectra are provided as
Supporting Information.)
Kinetic resolutions of the allylic alcohol 3 with L-(+)-
DIPT under the modified conditions gave the results
shown in Table 1. The absolute configuration for the
resolved allylic alcohol was assumed from the Sharpless
mnemonic and confirmed by the eventual synthesis of
(+)-grandisol 1 of known configuration.
Reaction of the allylic alcohol 3 with methanesulfonyl
chloride gave a poor yield of the unstable allylic chloride
14, formed by subsequent nucleophilic substitution by
chloride anion on the mesylate 15. This problem is
avoided by the use of methanesulfonic anhydride.35 The
mesylate 15 is obtained in a 78% yield after purification
(Scheme 2).
Reduction of the optically active and racemic mesylates
15, separately with lithium aluminum hydride in THF,
gave exclusively the corresponding endocyclic alkene 2,
1
analysis could be made by H NMR at 600 MHz on the
derived Mosher ester of the alcohol. The most reliable
region for analysis was for the resonances for the CH2
group bearing the COR group.34 In the spectrum for the
diastereomeric Mosher ester, derived from the racemic
allylic alcohol, this region consisted of overlapping AB
quartets, for the diastereotopic protons. One peak from
each diastereomer separated from all other signals. These
peaks did not represent the same part in each AB
quartet, and so a correction factor was obtained by
integration of these peaks in the spectrum. In this way
an estimate for the enantiomeric excess achieved in the
kinetic resolution could be made. In the ester from the
racemic alcohol the peaks at 4.93 and 4.88 are in the ratio
of 1:2, which is close to the theoretical value calculated
for the intensities of these peaks. Confirmation of this
interpretation for this part of the spectrum was obtained
later when samples of each optically enriched enantiomer
were obtained by the use of L-(+)-DIPT and D-(-)-DET
in separate kinetic resolution experiments. The AB
1
with no exocyclic alkene 7 detected by H NMR spectros-
copy.
To ensure that the method used to estimate the ee of
the allylic alcohol was reliable, a determination of the
ee of a sample of this alkene was made in the following
way. The optically active alkene 2, prepared from allylic
alcohol estimated to be 85% ee, was treated according to
the Sharpless dihydroxylation procedure36 with the achiral
ligand quinuclidine. The resultant diol 16 was then
converted to the mono Mosher’s ester. The H NMR (300
MHz) of the diastereomeric mixture of mono esters
obtained from the racemic diol showed two doublet of
1
quartet regions of the H NMR spectra (600 MHz) of the
Mosher esters from the racemic and two enriched samples
(31) Payne, G. B. J . Am. Chem. Soc. 1962, 27, 2819-3822. We are
not aware of any reports of a Lewis-acid-catalyzed Payne rearrange-
ment.
(32) Due to the instability of the olefin, microanalyses was not
attempted, and HR MS is not available in these laboratories.
(33) SGE Cydex-â, 25m × 0.22m. We would like to thank Dr M. G.
Banwell, A. N. U., Canberra, for chiral GC experiments.
(34) Almost complete separation of the methoxy signals is also
observed, but as this region could be contaminated with reagent
signals, it was used only for confirmation.
1
(35) Owen, L. N.; Whitelaw, S. P. J . Am. Chem. Soc. 1953, 75, 3723-
23.
(36) VanNieuwenhze, M. S., Sharpless, K. B. J . Am. Chem. Soc.
1993, 115, 7864-65.

Asymmetric Synthesis of (+)-Grandisol
J . Org. Chem., Vol. 65, No. 23, 2000 7843
1.82-1.95 (2H, complex, H4b, H7a), 2.0-2.1 (1H, multiplet,
H7b), 2.25-2.42 (3H, complex, H1, H3a, H6b), 2.68 (1H, dt, J
) 9.0, 11.0, 18.5 Hz, H3b). δC and DEPT (50 MHz): 18.7 (CH2),
25.8 (CH3), 30.6 (CH2), 35.4 (CH2), 38.3 (CH2), 42.5 (q), 50.2
(CH), 222.5 (CO). NMR data was consistent with the litera-
ture.41,42
doublets at δ 5.44 and 5.38 consistent with the protons
on the carbons bearing the ester groups. By integration
of each of these two doublet of doublets, for the enriched
sample an enantiomeric excess of 86% is obtained. This
established the reliability of our initial method and was
not used further.
A Mixt u r e of 3-Did eu t er a t ed (1SR,5SR)-5-Met h ylb i-
cyclo[3.2.0]h ep ta n -2-on e, 3,3-Did eu ter a ted (1SR,5SR)-5-
Meth ylbicyclo[3.2.0]h ep ta n -2-on e, a n d 1,3,3-Tr id eu ter -
a ted (1SR,5SR)-5-Meth ylbicyclo[3.2.0]h ep ta n -2-on e. A
solution of (1SR,5SR)-5-methylbicyclo[3.2.0]heptan-2-one 4
(121 mg, 0.98 mmol), K2CO3 (738 mg, 5.34 mmol), and D2O (5
mL, 273 mmol) in anhydrous THF (13 mL) were refluxed for
15 h under nitrogen. Et2O was added to the cooled solution,
and the reaction was washed with water. The organic phase
was dried, and solvent was removed in vacuo to give a mixture
of the mono-, di-, and tri-deuterio species as a colorless liquid
(105 mg, 85%). δH (300 MHz): 1.29 (s, 3H, CH3), 1.55-2.0
The synthesis of (+)-grandisol 1 was completed by a
combination of previously described chemistry. Thus on
a larger scale, the volatile alkene 2a was prepared via
the mesylate 15a , from allylic alcohol 3a of a 94% ee.
Then, without complete isolation from the solvent, it was
treated with RuCl3/NaIO4 under essentially the same
conditions as those reported by Rosini9 except that the
reaction was heated at 40 °C for 15 h. The crude optically
active ketoacid 17a was obtained in a 54% yield from the
mesylate 15a . Because the ketoacid 17a has a tendency
to epimerize it was not purified but was treated im-
mediately by the procedure of Webster,37 with methyl-
enetriphenylphosphorane to give the optically active
olefinic acid 18a in a 62% yield (76% for the racemate
18r ). Reduction of this acid gave, in a 95% yield, (+)-
grandisol 1a .37 The enantiopurity of grandisol 1a was
established as 95% ee, by conversion to the Mosher ester
followed by integration of the methyl resonances in the
1H NMR (600 MHz) spectum.38
In conclusion, therefore, we have developed a 10-step
asymmetric synthesis of the pheromone 1a , in an 8%
overall yield from achiral starting material 4. In prin-
ciple, by sacrificing the yield of the allylic alcohol 3a in
the kinetic resolution, the ee could be made even higher.
Furthermore the chemistry explored in connection with
this synthesis appears to have revealed a Lewis-acid-
catalyzed Payne rearrangement, of the hydroxy-epoxide
12, for which we know of no precedent.
1
(complex, 5H, H4, H6a, H7), 2.23-2.35 (complex, 11/2H, /2H1
and H6b). δC (50 MHz): 18.7, 25.8, 30.6, 35.4, 38.3 (t), 42.5,
50.2, 222.5. m/ z revealed the molecular ions (M+•) 127:126:
125:124 in the ratio of 3.8:24:3.5:1.
(1SR,2RS,5SR)-5-Meth yl-2-m eth ylen e oxid e bicyclo-
[3.2.0]h ep ta n e 5 a n d (1SR,2SR,5SR)-5-Meth yl-2-m eth yl-
en e oxid e bicyclo[3.2.0]h ep ta n e 6. (a ) With Tr im eth yl-
su lfoxon iu m Iod id e a n d Na H. To anhydrous, degassed
DMSO (7 mL) was added sodium hydride (dispersion, oil
removed) (123 mg, 5.11 mmol). The flask, under a nitrogen
atmosphere, was fitted with a gooch tube containing trimeth-
ylsulfoxonium iodide (1.21 g, 5.51 mmol). Sulfoxonium iodide
was added portionwise over 10 min. After the reaction mixture
had stirred at ambient temperature for 30 min (1SR,5SR)-5-
methylbicyclo[3.2.0]heptan-2-one 4 (502 mg, 4.04 mmol) was
added dropwise over 5 min. The reaction mixture stirred at
ambient temperature for 15 min and then heated at 55 °C for
2 h. After being cooled to ambient temperature, the reaction
mixture was poured into cold water and then extracted with
Et2O. The combined organic phases were washed with water
and sat. NaCl(aq). The organic phases were dried, and solvent
was removed by distillation at atmospheric pressure. An
evaporative distillation (kugelrohr), 70 °C/760 mmHg, gave the
Exp er im en ta l Section
1
title compounds as a colorless liquid (421 mg, 75%). H NMR
Gen er a l P r oced u r e. Melting points are uncorrected. 1H
NMR spectra were recorded in CDCl3 on a 200, 300, or 600
MHz spectrometer. MS and GC-MS were recorded at an
ionization energy of 70 eV. Elemental analyses were carried
out at the University of Otago, Dunedin, New Zealand.
Accurate mass determinations (LI-MIS) were made at the
University of Tasmania, Australia. GC analyses were carried
out on a DANI 8510 Gas Chromatograph with a SGE S.C. O.T
50m OV101 column. Flash chromatography was performed
with Merck Kieselgel 60 (230-400 mesh ASTM). TLC was
performed using Merck silica gel (60 F-254) plates which were
visualized either with UV light (254 nm) or by immersion in
acidic ammonium molybdate solution. Organic solutions were
dried over Na2SO4. Other anhydrous solvents and reagents
were prepared according to standard laboratory procedures.39
(1SR,5SR)-5-Meth ylbicyclo[3.2.0]h ep ta n -2-on e 4. Com-
pound 4 was synthesized following the method of Cargill12
except the apparatus was modified by an external jacket of
stainless steel rather than glass and enclosed with a nylon
socket. [CAUTION: With this apparatus it is an important
fire safety requirement to ensure that an atmosphere of CO2
blankets the whole apparatus whenever this 1000 W lamp is
turned on. This can be achieved by building walls high enough
around the “dry ice” acetone bath to ensure the escaping CO2
forms a blanket thereby excluding air.] The title compound
was obtained as a colorless liquid (19.0 g, 77%). 1H NMR (600
MHz):40 δ 1.26 (3H, s, CH3), 1.55-1.80 (2H, complex, H4a, H6a),
showed the presence of the two epoxides in a 43:57 ratio (endo-
5:exo-6). The data for these compounds 5 and 6 is detailed
below for the individual compounds. Accurate mass spec-
trum: (MH+) calcd 139.112, found 139.112.
(b) With Tr im eth ylsu lfon iu m Iod id e a n d Na H. Sodium
hydride (dispersion, oil removed) (323 mg, 13.4 mmol) was
added to anhydrous DMSO (4 mL) under a nitrogen atmo-
sphere. The reaction mixture heated to 72 °C, whereupon
hydrogen was given off. THF (8 mL) was added and the
solution subsequently cooled to 0 °C. Trimethylsulfonium
iodide (1.66 g, 6.31 mmol) dissolved in DMSO (10 mL) was
added over 3 min, and the mixture was stirred for a further
minute when (1SR,5SR)-5-methylbicyclo[3.2.0]heptan-2-one 4
(610 mg, 4.92 mmol) was added dropwise. After a further 10
min at 0 °C, the ice bath was removed and solution stirred at
ambient temperature for 2.5 h. The reaction mixture was then
diluted with water and extracted with CH2Cl2. The combined
organic extracts were washed with water and dried, and
solvent was removed in vacuo. An evaporative distillation
(kugelrohr) (150 °C/ 880 mmHg) gave the endo epoxide 5 as a
colorless liquid (466 mg, 68%). δH (600 MHz):40 1.26 (s, 3H,
CH3), 1.50 (td, J ) 7.2, 12.6 Hz, 1H, H4a), 1.67 (complex, 2H,
H4b and H3a), 1.82 (complex, 2H, H6a and H7a), 1.94 (complex,
2H, H1 and H6b), 2.06 (m, 1H, H7b), 2.45 (td, J ) 7.2, 13.2
Hz, 1H, H3b), 2.73 (dd, J ) 0.8, 5.4 Hz, 1H, H1′), 2.82 (d, J )
43
5.4 Hz, 1H, H1′). δC (50 MHz): 15.7 (CH2, C7), 26.6 (CH3),
(37) Webster, F. X., Silverstein, R. M. J . Org. Chem. 1986, 51, 5226-
31.
(38) Mori, K.; Miyake, M. Tetrahedron 1987, 43, 2229-39.
(39) Perrin, D. D., Armarego, W. L. F., Purification of Laboratory
Chemicals, 3rd ed.; Pergamon Press: Oxford, 1988.
(40) COSY and (H, C) COSY were used to assign the resonances.
(41) Langer, K.; Mattay, J .; Heidbreder, A.; Mo¨ller, M. Liebigs. Ann.
Chem. 1992, 257-60.
(42) Schwartz, N. N.; Blumbergs, J . H. J . Org. Chem. 1964, 29,
1976-79.

7844 J . Org. Chem., Vol. 65, No. 23, 2000
Hamon and Tuck
30.3 (CH2, C6), 31.6 (CH2, C3), 37.7 (CH2, C4), 44.3 (q), 45.1
A suspension of the tosylhydrazone 9 (1.04 g, 3.59 mmol)
and TMEDA (15 mL) was cooled to -78 °C, under a nitrogen
atmosphere. A solution of nBuLi (2.3 M, 4.6 mL, 10.58 mmol)
was added dropwise to the frozen suspension, and the solution
generated was kept at -78 °C for 15 min and then allowed to
warm to ambient temperature, whereupon it turned a dark
red color. This solution was stirred for a further 5 h, it was
cooled to 0 °C, DMF (0.4 mL, 5.18 mmol) was added, and the
solution was stirred at ambient temperature overnight. It was
then poured into 7.5% HCl(aq) (60 mL) and extracted with CH2-
Cl2 (4 × 40 mL). The combined organic phases were washed
with sat. NaCl(aq) (40 mL) and dried, and solvent was removed
in vacuo. The crude material was used directly in the next
reaction. A small portion was purified by flash chromatography
(CH2Cl2) to give a pure sample for spectroscopic analysis. δH
(300 MHz): 1.30 (s, 3H), 1.6-2.1 (m, 3H), 2.2-2.6 (m, 3H),
3.02 (br d, 1H, J ) 8.2 Hz), 6.87 (br s, 1H), 9.78 (s, 1H). δC (75
MHz): 23.4, 24.6, 33.0, 44.4, 46.9, 47.9, 150.8, 152.6, 190.1.
(CH, C1), 57.0 (CH2, C1′), 67.2 (q). m/z: 138(M+•, 30%), 55(100).
(1S R ,5S R )-5-Me t h yl-2-m e t h yle n e b icyclo[3.2.0]h e p -
ta n e 7. Compound 7 has been previously prepared by Rosini,
by an alternative procedure.7 To a solution of methyltri-
phenylphosphonium iodide (4.23 g, 10.5 mmol) in Et2O (25
mL), under a nitrogen atmosphere, was added, over 5 min,
t-BuOK (1.62 g, 14.5 mmol). The mixture was stirred at
ambient temperature for 20 min, the yellow reaction mixture
was cooled to 0 °C, and (1SR,5SR)-5-methylbicyclo[3.2.0]-
heptan-2-one 4 (1.10 g, 8.94 mmol) was added dropwise. After
being stirred for 15 h at ambient temperature, the still-yellow
solution was filtered through Celite, and solvent was removed
at atmospheric pressure. An evaporative distillation (kugel-
rohr) 760 mm/60 °C gave the title compound as a colorless
liquid (436 mg, 40%). δH (200 MHz): 1.20 (s, 3H), 1.2-2.0
(complex, 5H), 2.30 (complex, 2H), 2.42 (dm, 1H, 16.6 Hz), 2.75
(m, 1H), 4.66 (br s, 1H), 4.76 (br s, 1H). δC (50 MHz): 22.0,
26.4, 30.2, 33.2, 40.2, 45.8, 48.7, 104.3, 158.5. Analysis and
HR MS were not obtained.
υ
max(neat): 1680(s) cm-1. m/z: 136(M+•, 11%), 79(100).
Red u ction of th e Ald eh yd e 10. To the crude aldehyde
10 (∼2 g, max. 3.5 mmol) dissolved in MeOH (15 mL) was
added ceric chloride (0.1 mL), and the reaction vessel placed
under a nitrogen atmosphere. Solid NaBH4 (201 mg, 5.32
mmol) was added with stirring over 10 min, and after 4 h the
solution was diluted with CH2Cl2 and washed with 7.5%
HCl(aq). The aqueous phase was further extracted with CH2-
Cl2. The combined organic extracts were washed with sat.
NaCl(aq) and dried, and solvent was removed in vacuo. Flash
chromatography (CH2Cl2) gave the title compound (477 mg,
83% over two steps). δH (600 MHz):40 1.27 (s, 3H, CH3), 1.69
(m, 1H, H7a), 1.79 (m, 1H, H6a), 1.94 (m, 1H, H6b), 2.1-2.3
(complex, 3H, H4, H7b), 2.74 (d, J ) 7.8 Hz, 1H, H1), 4.12 (AB
quartet, J ) 15.5 Hz, 1H, H1a′), 4.20 (AB quartet, J ) 15.5
Hz, 1H, H1b′), 5.62 (s, 1H, H3). δC and DEPT (75 MHz): 23.2
(CH2), 25.0 (CH), 33.2 (CH2), 44.4 (q), 47.2 (CH2), 50.1 (CH3),
60.5 (CH2), 125.0 (CH), 146.9 (q).M/z: 138(M+•, 15%), 95(100).
Anal. Calcd for C9H14O: C, 78.21; H, 10.20 Found: C, 78.19;
H, 9.96.
(1SR,2RS,5SR)-5-Meth yl-2-m eth ylen e oxid e bicyclo-
[3.2.0]h ep ta n e 5 a n d (1SR,2SR,5SR)-5-Meth yl-2-m eth yl-
en e oxid e bicyclo[3.2.0]h ep ta n e 6. The alkene 7 (30 mg,
0.25 mmol) was added to the two-phase solution of Et2O (3
mL) and 0.68 M NaHCO3(aq) (3 mL). After the mixture was
cooled to -5 °C, mCPBA (90% mCPBA, 71 mg, ∼0.37 mmol)
was added portionwise over 15 min. The mixture was then
allowed to stir at ambient temperature for 15 h. CH2Cl2 (20
mL) and water (10 mL) were added, the organic phase was
separated, this was washed successively with 1 M NaOH(aq)
and water and dried, and the solvent was removed in vacuo
to give the title compounds (21 mg, 60%). 1H NMR showed
the presence of the two epoxides in a 20:80 ratio (endo-5:exo-
6). The major signals were for the isomer 6. δH (600 MHz):
1.20 (s, 3H, CH3), 1.5-2.2 (complex, 8H, H1, H3a, H4, H6, H7),
2.56 (td, J ) 7.8, 13.8 Hz, 1H, H3b), 2.70 (d, J ) 4.5 Hz, 1H,
H1′), 2.79 (d, J ) 4.5 Hz, 1H, H1′). δC (50 MHz): 17.5, 26.4,
29.6, 32.7, 38.9, 45.3, 47.9, 48.5, 69.4.
1-Oxa sp ir o[2.5]oct-2-ylm eth a n ol 12 fr om Sh a r p less
Asym m etr ic Ep oxid a tion Rea ction . F or m a tion of 2-(1-
Cycloh exen yl)oxir a n e 13. Following the procedure of Sharp-
less,28 an anhydrous flask was flushed with nitrogen and
charged with n-decane (40 µL), (L)-(+)-DIPT (27 mg, 0.12
mmol), activated powdered 4 Å sieves (38 mg), and a solution
of the alcohol 11 (100 mg, 0.80 mmol) in anhydrous CH2Cl2 (2
mL), previously dried over 3 Å sieves for 1 h. The flask was
cooled to -20 °C, titanium(IV) isopropoxide (0.35 mL, 0.08
mmol) was added, and the solution was stirred at -20 °C for
1 h. The flask was then cooled to -40 °C, and tert-butyl
hydroperoxide solution (0.15 mL of a 4.2 M CH2Cl2 solution,
0.63 mmol), previously dried19 and then freshly dried over
freshly activated 3 Å sieves for 15 min, was added. At timed
intervals, aliquots (0.1 mL) of the reaction mixture were taken
(with an oven dried syringe) and quenched with 0.1 mL of a
solution of FeSO4 (1.6 g/5 mL) and citric acid (0.5 g/5 mL),
CH2Cl2 (0.1 mL) was added, and the organic layer was
separated. The organic layer was then analyzed by GLC (150
°C) for the remaining allylic alcohol relative to the internal
standard n-decane. After the reaction was complete, it was
quenched with a solution of FeSO4 (1.6 g/5 mL) and citric acid
(0.5 g/5 mL) and then left for 15 h. The reaction mixture was
diluted with CH2Cl2, the organic layer was separated, and the
aqueous layer was re-extracted with CH2Cl2. The combined
organic phases were washed with sat. NaCl(aq) and dried, and
solvent was removed in vacuo. Flash chromatography (hex-
anes/EtOAc, 70/30 v/v) did not give the expected product but
a colorless liquid identified as 2-(1-cyclohexenyl)oxirane32 13
(47%). δΗ (200 MHz): 1.5 (complex, 4H), 1.8 (complex, 4H),
3.4-3.7 (AB of ABX, 2H), 3.9-4.1 (X of ABX, 1H), 5.66 (br s,
1H). δC (150 MHz): 22.4, 22.5, 24.8, 24.9, 65.4, 76.2, 123.9,
136.7. GC/MS: 124 (M+, 65%), 95 (100).
Attem p ted F or m a tion of [(1RS,5SR)-5-Meth ylbicyclo-
[3.2.0]h ep t-2-en -2-yl]m eth a n ol 3. To a solution of CH2Cl2
(1.5 mL), DBU (0.2 mL), and endo-epoxide 5 (99 mg, 0.72
mmol) was added TMSOTf (0.2 mL). The solution was stirred
for 15 h under a nitrogen atmosphere and at ambient tem-
perature, 15% HCl(aq) (5 mL) and CH2Cl2 (10 mL) were added,
and the aqueous layer was separated. The aqueous phase was
re-extracted with CH2Cl2 (2 × 10 mL). The combined organic
phases were washed with sat. NaCl(aq) (10 mL) and dried, and
solvent was removed in vacuo. Flash chromatography (CH2-
Cl2/hexanes 15/85 v/v) gave the title compound as a colorless
liquid (27 mg, 27%). 1H NMR data was identical with that
obtained later for the alcohol 3.
A Mixtu r e of E a n d Z Isom er s of N′-1-[(1SR,5SR)-5-
Met h ylb icyclo[3.2.0]h ep -2-ylid en ]-4-m et h yl-1-t olu en e-
su lfon oylh yd r a zon e 9. Tosylhydrazine (3.53 g, 18.9 mmol)
was added to 60% MeOH(aq) (46 mL) heated to 60 °C.
(1SR,5SR)-Methylbicyclo[3.2.0]heptan-2-one 4 (2.33 g, 18.8
mmol) was then added dropwise to the clear solution. The
reaction mixture was immediately stored at 5 °C for 15 h. The
resultant white crystals were filtered, washed with 60%
MeOH(aq), and air-dried for 10 min. The title compound was
1
obtained as white crystals (4.91 g, 89%), mp 174-176 °C. H
NMR revealed a 1:1 mixture of isomers. δH (200 MHz): 1.21
(s, 3H, CH3), 1.23 (s, 3H, CH3), 2.42 (br s, 6H, Ar-CH3), 1.35-
2.9 (m, 18H, ring protons), 4.06 (br s, 2H, NH), 7.30 (dm, J )
8.0 Hz, 4H, Ar), 7.82 (d, J ) 8.0 Hz, 4H, Ar). δC (50 MHz):
18.6, 21.4, 21.5, 25.3, 25.5, 27.9, 29.8, 30.0, 33.2, 36.7, 37.3,
42.1, 44.1, 45.9, 48.0, 127.9, 129.5, 135.6, 143.58, 171.4, 172.3.
υ
max: 3297, 3220 (2 peaks, NH) cm-1. m/z: 293 (M+•,100%),
137 (94). Anal. Calcd for C15H20O2SN: C, 61.61; H, 6.89.
Found: C, 61.48; H, 7.03.
[(1RS,5SR)-5-Meth ylbicyclo[3.2.0]h ep t-2-en -2-yl]m eth -
a n ol 3. F or m a tion of th e Ald eh yd e 10. [CAUTION: Ni-
trogen is produced in this reaction and allowance must be
made for its escape. Do not use a sealed system.]
F or m a tion of 1-Oxa sp ir o[2.5]oct-2-ylm eth a n ol 12. The
above procedure was repeated with the following quantities:
n-decane (40 µL), (L)-(+)-DIPT (24 mg, 0.10 mmol), activated
powdered 4 Å sieves (33 mg), a solution of the alcohol 11 (102

Asymmetric Synthesis of (+)-Grandisol
J . Org. Chem., Vol. 65, No. 23, 2000 7845
mg, 0.81 mmol) in anhydrous CH2Cl2 (2 mL), titanium(IV)
isopropoxide (0.35 mL, 0.08 mmol), and tert-butyl hydroper-
oxide solution (0.16 mL of a 3.8 M CH2Cl2 solution, 0.61 mmol).
At timed intervals, aliquots (0.1 mL) of the reaction mixture
were taken (with an oven dried syringe) and quenched with
0.1 mL of a solution of FeSO4 (1.6 g/5 mL) and citric acid (0.5
g/5 mL), CH2Cl2 (0.1 mL) was added, and the organic layer
was separated. After the reaction was complete, it was
quenched with sodium thiosulfate (5 mL) and then left for 2
days (for comparison with the above FeSO4 solution). Upon
workup and flash chromatography (hexanes/EtOAc, 70/30 v/v)
the title compound was obtained as a colorless oil (52 mg, 45%)
with no rearranged epoxide 13 present in the 1H NMR
spectrum. δΗ (300 MHz): 1.5-1.8 (complex, 10H, methylene
envelope), 2.2 (br s, 1H, OH), 2.9-3.1 (X portion of ABX, 1H),
3.6-4.0 (AB of ABX, 2H).
ambient temperature. CH2Cl2 was added, and the organic
phase was separated. The aqueous phase was re-extracted
with CH2Cl2. The combined organic phases were washed with
sat. NaCl(aq) and dried, and solvent was removed in vacuo.
Flash chromatography (hexanes/EtOAc 85/15 v/v) gave the
(1R,5S) allylic alcohol as a colorless oil (490 mg, 31% recovery).
δH (300 MHz): 1.27 (s, 3H, CH3), 1.35-2.5 (m, 6H, ring
protons), 2.75 (br d, J ) 5.6 Hz, 1H, H4), 4.20 (AB quartet,
2H, H1′), 5.62 (br s, 1H, H3). [R]20 ) -1.77 ( 0.2 (c ) 1.5
D
CH2Cl2). The ee was calculated to be 94 ( 2% by conversion
to the corresponding Mosher ester, diastereomer B above.
In a similar manner by the use of D-(-)-DET, but by letting
the reaction go to 85% conversion, the other enantiomer was
obtained. Conversion to the corresponding Mosher ester gave
mainly diastereomer.
Ra cem ic 15r a n d [(1R,5S)-5-Meth ylbicyclo[3.2.0]h ep t-
2-en -2-yl]m eth yl m eth a n esu lfon a te 15a . Methanesulfonic
anhydride35 (846 mg, 4.85 mmol) was added portionwise to a
solution of the allylic alcohol 3 (438 mg, 3.17 mmol) and
triethylamine (1 mL) in CH2Cl2 (4 mL) and cooled to 0 °C, and
the mixture was stirred at ambient temperature for 2.5 h
before the solution was diluted with CH2Cl2 and washed with
15% HCl(aq). The aqueous phase was re-extracted with CH2-
Cl2. The combined organic layers were washed with sat.
NaCl(aq) and dried, and solvent was removed in vacuo. Puri-
fication by flash chromatography (hexanes/EtOAc 75/15 v/v)
gave 15r as a colorless oil (543 mg, 78%). δH (300 MHz): 1.29
(s, 3H, CH3), 1.4-2.0 (m, 3H, ring protons), 2.33 (m, 3H, ring
protons), 2.78 (m, 1H, allylic proton), 3.00 (s, 3H, O2S-CH3),
4.79 (s, 2H, H1′), 5.85 (br s, 1H, H3). δC (75 MHz): 23.2, 25.0,
33.1, 37.8, 44.6, 47.4, 50.2, 67.5, 132.2, 140.2. υmax(neat):
2869(s), 1425(s), 1253(s) cm-1. m/z: 217 (MH+, 6%), 95 (83),
79 (100).
Mosh er E st er of t h e R a cem ic Allylic Alcoh ol 3r :
[(1SR,2RS,5SR)-5-Meth ylbicyclo[3.2.0]h ep -2-en -yl]m eth -
yl (2R)-3,3,3-Tr iflu or o-2-m eth oxy-2-p h en ylp r op a n oa te.
According to the procedure of Hassner,44 a solution of the (R)-
(+)-R-methoxy-R-(trifluoromethyl)phenylacetic acid (26 mg,
0.11 mmol), DCC (19 mg, 0.090m mmol), the racemic alcohol
3r (14 mg, 0.102 mmol), and DMAP (2 mg, 0.019 mmol) in
CH2Cl2 (0.7 mL) were allowed to stand at ambient temperature
until esterification was complete. N,N-Dicyclohexylurea was
filtered, the filtrate washed with water, 5% citric acid solution,
and again with water and dried, and the solvent was evapo-
rated in vacuo. Flash chromatography (hexanes/EtOAc,45 95/
5, v/v) as an eluant gave the corresponding Mosher ester as a
colorless oil (15 mg, 55%). The diastereomers could not be
1
distinguished in the H NMR spectrum at 200 MHz. From the
1H NMR spectrum (600 MHz) of the products from the racemic
and optically active alcohols it was possible to assign the
following data. Diastereomer A δH (600 MHz): 1.27 (s, 3H),
1.3-2.0 (complex, 3H), 2.24 (m, 3H), 2.62 (m, 1H), 3.55 (br s,
3H), (AB quartet, one centered at 4.84, 1H and the other at
4.91, 1H), 5.69 (br s, 1H), 7.35-7.55 (m, 5H). Diastereomer B
δH (600 MHz): 1.24 (s, 3H), 1.3-2.0 (complex, 3H), 2.24 (m,
3H), 2.62 (m, 1H), 3.56 (br s, 3H), (AB quartet, one centered
at 4.84, 1H and the other at 4.89, 1H), 5.70 (br s, 1H), 7.35-
7.55 (m, 5H).
The above procedure was repeated with methanesulfonic
anhydride35 (629 mg, 3.60 mmol), the allylic alcohol 3a (471
mg, 3.40 mmol), triethylamine (0.5 mL), and CH2Cl2 (4 mL).
After purification, 15a was obtained as a colorless oil (583 mg,
1
78%). H NMR data of 15a were identical with those of 15r .
Ra cem ic 2r a n d (1S,5R)-2,5-Dim eth ylbicyclo[3.2.0]-
h ep t-2-en e 2a . A suspension of LiAlH4 (122 mg, 3.21 mmol)
and THF (3 mL), under a nitrogen atmosphere, was cooled to
0 °C. A solution of the mesylate 15r (350 mg, 1.60 mmol) in
THF (3 mL) was cautiously added, and the solution was stirred
at ambient temperature for 15 h. The solution was carefully
quenched with water and then poured into water. The solution
was extracted with CH2Cl2. The combined organic layers were
washed with water and sat. NaCl(aq) and then dried, and
solvent was removed by distillation at atmospheric pressure.
The racemic alkene 2r was obtained as a clear oil, with some
solvent impurity (450 mg). It was used crude in the next
reaction. δH (300 MHz): 1.25 (s, 3H), 1.4-2.0 (m, 3H), 1.71
(br s, 3H), 2.10 (m, 3H), 2.55 (m, 1H), 5.28 (br s, 1H). δC (75
MHz): 14.5, 22.9, 25.1, 33.2, 44.4, 47.6, 53.6, 124.2, 143.1.
Resonances for THF and CH2Cl2 were also present. GC-MS:
123 (MH+, 32%), 79 (100). 1H NMR and 13C data corresponded
with the literature values.7,9
Kin et ic R esolu t ion of [(1RS,5SR)-5-Met h ylb icyclo-
[3.2.0]h ep t-2-en -2-yl]m eth a n ol 3. In general, these reactions
were run as follows although the scale, number of aliquots,
and the time of quenching were varied throughout the studies.
A solution of L-(+)-DIPT (295 mg, 1.26 mmol), titanium
isopropoxide (196 mg, 0.69 mmol), freshly activated powdered
4 Å sieves (337 mg), and freshly distilled anhydrous CH2Cl2
(4 mL) were combined, put under a small pressure of dry
nitrogen, and cooled to -15 °C. tert-Butyl hydroperoxide (1.1
mL, 5.9 M, 6.4 mmol), previously dried19 and then freshly dried
over freshly activated 3 Å sieves for 15 min, was added, and
the solution was then cooled to -40 °C and aged at -40 °C for
2 h. Then a solution of n-decane (0.4 mL) and the allylic alcohol
3 (1.63 g, 11.8 mmol) in CH2Cl2 (5 mL), which had been drying
over freshly activated 3 Å sieves for 15 min, were added, the
sieves were washed with additional CH2Cl2 (2 mL), and the
washings were also added to the reaction mixture. [A To GLC
sample had been taken from the n-decane and allylic alcohol
solution before it was added to the reaction mixture.] After
the reaction had been stirred at -40 °C for 15 h, an aliquot
(0.1 mL) was removed (with an oven dried syringe) and
quenched with 0.1 mL of a solution of FeSO4 (1.6 g/5 mL) and
citric acid (0.5 g/5 mL), CH2Cl2 (0.1 mL) was added, and the
organic layer was separated. GLC showed that the reaction
had gone to 59% completion. Sodium thiosulfate (3 mL) was
added, and the reaction mixture was allowed to warm to
The above procedure was repeated with LiAlH4 (146 mg,
3.84 mmol), THF (4 mL), and the mesylate 15a (583 mg, 2.66
mmol) in THF (3 mL). After solvent was removed by distilla-
tion at atmospheric pressure, 2a was obtained as a clear oil,
with some solvent impurity. It was used crude in the next
1
reaction. The H NMR spectrum was the same as that for 2r .
Ra cem ic 16r a n d (1R,2S,3R,5R)-2,5-Dim eth ylbicyclo-
[3.2.0]h ep ta n e-2,3-d iol 16a . Following the procedure of
Sharpless,36 a 25-mL round-bottom flask was charged with
tBuOH (1.5 mL) and water (1.5 mL). Potassium carbonate (134
mg, 0.97 mmol), potassium ferricyanide (369 mg, 1.12 mmol),
quinuclidine hydrochloride (1 mg, 0.01 mmol), 4% OsO4(aq) (0.02
mL, 0.8 mg, 0.003 mmol), and methane sulfonamide (30 mg,
0.31 mL) were then added. To the well-stirred solution was
added alkene 2r (35 mg, 0.29 mmol). Once the reaction was
complete (15 h), solid sodium sulfite (430 mg, 3.41 mmol) was
added and the solution stirred at ambient temperature for 30
min. CH2Cl2 was added to the reaction mixture, and after
separation of the layers, the aqueous phase was further
(43) DEPT and (H, C) COSY experiments were used to assign the
resonances.
(44) Hassner, A.; Alexanian, V. Tetrahedron Lett. 1978, 4475-78.
(45) In the preparation of Mosher esters for optical purity measure-
ments, purification by chromatography was performed with a short
column and care was taken so as to avoid possible fractionation of
diastereomers.

7846 J . Org. Chem., Vol. 65, No. 23, 2000
Hamon and Tuck
extracted with CH2Cl2. The combined organic extracts were
dried and concentrated to give the diol 16r and the ligand.
The crude product was purified by flash chromatography
(hexanes/EtOAc 70/30 v/v) to afford the 1,2-diol 16r as white
crystals (15 mg, 60%). Mp 66-67 °C. δH (300 MHz): 1.20 (s,
3H), 1.22 (s, 3H), 1.4-2.2 (m, 7H), 4.19 (dd, 1H, J ) 7.0, 10.5
Hz). δC (75 MHz): 16.5, 20.1, 28.2, 30.9, 40.4, 46.5, 52.8, 77.9,
80.6. υmax(CDCl3): 3608 (b, OH), 3432 (b, OH), cm-1. m/ z: 156
(MH+,1%), 67 (25), 43 (100).
1-m eth ylcyclobu tyl]eth oxy}-1-m eth oxy-1-(tr iflu or om eth -
yl)-2-p r op en yl]ben zen e. The general procedure for Mosher
formation44 was repeated with the following reagents: racemic
grandisol 1r (8 mg, 0.05 mmol), DMAP (1 mg, 0.01 mmol), DCC
(14 mg, 0.07 mmol), (R)-(+)-R-methoxy-R-(trifluoromethyl)-
phenylacetic acid (18 mg, 0.08 mmol), and CH2Cl2 (0.5 mL).
The corresponding Mosher ester was obtained as a colorless
oil (12 mg, ∼65%). From the 1H NMR spectrum of the products
from the racemic and optically active esters it was possible to
assign the following data.
Diastereomer A: δH (600 MHz): 1.14 (s, 3H), 1.64 (s, 3H),
1.45-1.65 (complex, 3H), 1.75-2.0 (complex, 3H), 2.58 (t, 1H,
J ) 9.0 Hz), 3.55 (br s, 3H), 4.37 (m, 2H), 4.64 (br s, 1H), 4.84
(br s, 1H), 7.35-7.55 (m, 5H). Diastereomer B: δH (600 MHz):
1.15 (s, 3H), 1.65 (s, 3H) 1.45-1.65 (complex, 3H), 1.75-2.0
(complex, 3H), 2.58 (t, 1H, J ) 9.0 Hz), 3.55 (br s, 3H), 4.37
(m, 2H), 4.64 (br s, 1H), 4.84 (br s, 1H), 7.35-7.55 (m, 5H).
The above procedure was repeated with the following
reagents; grandisol 1a (7 mg, 0.04 mmol), DMAP (5 mg, 0.04
mmol), DCC (20 mg, 0.10 mmol), (R)-(+)-R-methoxy-R-(tri-
fluoromethyl)phenylacetic acid (20 mg, 0.09 mmol), and CH2-
Cl2 (0.5 mL). The corresponding Mosher ester was obtained
as a colorless oil, mainly diastereomer B (11 mg, ∼70%). Due
to the closeness of the resonances the ee were calculated by
cutting and weighing the methyl resonances at ∼δ 1.15. The
ee was found to be 94 ( 2%.
The general procedure (above) was repeated with potassium
carbonate (124 mg, 0.89 mmol), potassium ferricyanide (303
mg, 0.92 mmol), quinuclidine hydrochloride (2.3 mg, 0.03
mmol), tBuOH (2 mL), H2O (2 mL), 4% OsO4(aq) (0.05 mL, 2.0
mg, 0.007 mmol), and (1SR,5RS)-2,5-dimethylbicyclo[3.2.0]-
1
hept-2-ene 2a (20 mg, 0.16 mmol). The H NMR spectrum was
the same as that for 16r .
Mon o-Mosh er Ester of th e Ra cem ic Diol 16r a n d th e
Op tica lly Active Diol 16a : (1R,3R,4S,5R)-4-Hyd r oxy-1,4-
dim eth ylbicyclo[3.2.0]h ep-3-yl (2R)-3,3,3-Tr iflu or o-2-m eth -
oxy-2-p h en ylp r op a n oa te. The general procedure for Mosher
ester formation44 was repeated with the following reagents.
Diol 16r (8 mg, 0.05 mmol), DMAP (2 mg, 0.01 mmol), DCC
(23 mg, 0.11 mmol), (R)-(+)-R-methoxy-R-(trifluoromethyl)-
phenylacetic acid (23 mg, 0.10 mmol), and CH2Cl2 (0.5 mL).
The corresponding mono-Mosher ester was obtained as a
colorless oil (16 mg, 85%). From the 1H NMR spectra of the
products from the racemic and optically active diols it was
possible to assign the following data. Diastereomer A: δH (600
MHz): 1.20 (s, 3H), 1.27 (s, 3H), 1.1-2.2 (complex, 7H), 3.55
(br s, 3H), 5.38 (dd, 1H, J ) 7.0, 11.0 Hz), 7.35-7.55 (m, 5H).
Diastereomer B: δH (600 MHz): 1.10 (s, 3H), 1.25 (s, 3H) 1.1-
2.2 (complex, 7H), 3.57 (br s, 3H), 5.44 (dd, 1H, J ) 6.5, 11
Hz), 7.35-7.55 (m, 5H).
Ack n ow led gm en t. We acknowledge the receipt of
an Australian Postgraduate Research Award (to K.L.T.),
and thank Dr M.G. Banwell, A.N.U., Canberra, for
chiral GC experiments.
The above procedure was repeated with the enantiomeri-
cally enriched diol 16a , 85% ee (5 mg, 0.03 mmol), DMAP (2
mg, 0.02 mmol), DCC (13 mg, 0.06 mmol), (R)-(+)-R-methoxy-
R-(trifluoromethyl)phenylacetic acid (13 mg, 0.06 mmol), and
CH2Cl2 (0.5 mL) and gave the corresponding optically active
Mosher ester, mainly diastereomer B (8 mg, 63%). The ee was
found to be 86 ( 3% by integration of the pair of dd at δ 5.38
and 5.44.
Su p p or tin g In for m a tion Ava ila ble: Experimental de-
tails for the synthesis of the compounds 17a , 17r , 18a , 18r ,
1a , and 1r . (H,H) COSY and (H,C) COSY spectra of the ketone
1
4, the epoxide 5, and the alcohol 3. A H NMR spectra of the
diastereotopic protons of the Mosher esters from the racemic
and two enriched samples of the enantiomers of the alcohol 3.
This material is available free of charge via the Internet at
http://pubs.acs.org.
Mosh er Ester of Ra cem ic Gr a n d isol 1r a n d Op tica lly
Active Gr a n d isol 1a : 1-[(1R)-2-{2-[1R,2S)-2-Isop r op en yl-
J O000853+