Note: Descriptions are shown in the official language in which they were submitted.
~1 ~'7~ 4
-1- 16643
TITLE OF THE INVENTION
(+) (4R, 6S)-(E)-6-[2-(4'-fluoro-3,3',5-trimethyl-
[l,l'-biphenyl]-2-yl)ethenyl]-3,4,5,6-tetrahydro-4-
hydroxy-2H-pyran-2-one
SUMMARY OF THE INVENTION
: This invention relates to a hypocholesterol-
emic and hypolipemic compound which is a member of
the class of compounds having the structure (I)
: HO ~ O
~=/
:
Rl 5 ~ 2
R3
~ ~ '
::
3~'
'^' ~ :
.
~ 2 - 16643
and the corresponding dihydroxy acid resulting from
the hydrolytic opening of the lactone ring, and
pharmaceutically acceptable salts of said acid.
Specifically, it is the compound of structure I
wherein E is trans-CH=CH-, Rl is 6-(4'-fluoro-3'-
methyl-l-phenyl), R2 is 2-methyl, and R3 is 4-methyl.
BACKGROUND OF THE INVENTION
Recently, Endo et al, reported (U.S. Letters
Patent 4,049,495, Patent 4,137,322 and Patent
3,983,140) the production of a fermentation product
which was quite active in the inhibition of
cholesterol biosynthesis. This natural product, now
called compac-tin, was reported by Brown et al., (J.
Chem. Soc. Perkin I, 1165 (1976)~ to have a complex
mevalonolactone structure.
Recent U.S. Patents 4,138,425 and 4,255,444
disclose a group of synthetic compounds of the
generic formula II A
HO
Rl t ~ R2
R
II 3
in which A is -CH3 and hydrogen respectively, E
represents a direct bond, a C1 3 alkylene bridge or
a vinylene bridge and the R groups represent a
variety of substituents.
. ,`.~
- 3 - 16643
A patent application of Merck & Co., Inc.,
E.P. publication 0 024 348, discloses a similar
series of synthetic compounds in which A is hydrogen
and in which the lactone ring :has a (4R)-trans
configuration, the isomer which demonstrates all of
the antihypercholesterolemic activity of the
unresolved, cis-trans lactone mixture.
Now, with the present invention there is
provided the compound, (+)-(4R, 6S)-(E)-6-[2-(3,3',5-
trimethyl-4'~fluoro-[l,l'-biphenyl]-2-yl)ethenyl]-
3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one, which
has an unexpectedly high order of efficacy relative
to other members of the genus of which it is a member
and which is disclosed in the above-mentioned E.P.
publication 0 024 348.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a hypocholesterol-
emic and hypolipemic compound having the structure
20 III. H
HO ~ o
CH3 ~
~ ~ ~ 3
: CH3 III
~: 30
_ 4 _ 16643
or the corresponding dihydroxy acid resulting from
the hydrolytic opening of the lactone ring, or a
pharmaceutically acceptable salt of the acid, the
compound being the enantiomer with a 4 (R)
configuration in the tetrahydropyran moiety of the
trans racemate shown in the structures I and III.
The designation 4 (R) with respect to this
compound indicates that the absolute configuration in
space at the 4-carbon of the tetrahydropyranone ring
is believed to be the Rectus (R) series, and it is
dextrorotatory, and it is an unexpectedly potent
inhibitor of cholesterol biosynthesis, surpassing the
inhibitory activity of compactin.
The cited U.S. Patents 4,138,425 and
4,255,444 show no recognition of the stereochemistry
of compounds II, let alone the fact that an
unexpectedly large improvement in the activity would
result from the separation of the cls and trans
racemates and the latter's resolution, especially
when the preferred 2,4,6-trisubstitution occurs in
the phenyl ring. However, E.P. publication 0 024 348
discloses that the 4 (R) enantiomers of the trans
racemates corresponding to formula I specifically
inhibit with high potency the activity of
3-hydroxy-3-methylglutaryl-coenzyme A reductase,
which is known to be the enzyme involved in the rate
limiting step in the process of cholesterol
biosynthesis.
The compound III of this invention is the
most efficacious member of the latter series. The
inhibitory activity of these compounds for the
biosynthesis of cholesterol has been measured by two
'7~ ~4
_ 5 _ ~6643
methods. The experimental method A of U.S. 4,138,425
was the ln vitro method of H. J. Knauss, et al., J.
Biol. Chem., 234, 2835 (1959) and the activity was
expressed as the molar concentration IC50(M)
necessary for the inhibition of 50% of the enzymatic
activity. The experimental method B of U.S.
4,198,425 was the method of A. A. Kandutsch, et alO,
J. Biol. Chem., 248, 8403 (1973) for measuring
14C-cholesterol biosynthesis from acetic acid-14C
in mouse L cells. The activity is expressed for
inhibition of 50% of the biosynthesis of cholesterol.
The results obtained in these two asays for
the compounds of Structure II, as reported in the
cited U.S. patents, show IC50 values of 10 4 to
10 6 in both tests. The smallest 50% effective
dose cited is about 4 x 10 6, whereas the value for
compactin, in the same tests, is about 0.8 x 10 8.
E.P. publication 0 024 348 shows that the
inhibitory potency is greatly increased by separation
of isomers especially when this is combined with
optimal selection of a 2,4,6-arrangement of Rl, R2
and R3 in the phenyl ring of structure II and
especially when A is hydrogen and E is trans-CH=CH-.
Thus the (+) trans enantiomer of 6-E2-(2f4-dichloro-6-
(phenylmethoxy)phenyl)ethyl]-3,4,5,6-tetrahydro-4-
hydroxy-2H-pyran-2-one gives an IC50 of 6.8 x 10 8
in the test by method A. An even more potent
compound is the (+) trans enantiomer of (E)-6-[2-(3,5-
dichloro-4'-fluoro[l,l'-biphenyl]-2-yl)ethenyl]-
3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one and
- 6 - 16643
the compoun~ of the present invention, the (~)-trans
enantiomer of (E)-6-[2-(4'-fluoro-3,3',5-
trimethyl[l,l'-biphenyl]-2-yl)ethenyl]-3,4,5,6-
tetrahydro-4-hydroxy-2H-pyran-2-one, is several times
more potent.
The compounds were tested as the sodium
salts of their corresponding dihydroxy acld forms.
The compound of this invention has the added
advantage of having no chloro substituents. Although
the metabolism of the compound is not completely
known it is advantageous not to have a compound that
could be metabolized to a polychlorobiphenyl (PCB), a
class of substances known to be involved in
carcinogenesis.
The Flow Sheet shows the synthesis of the
4 (R) trans lactone of this invention. The number of
each step in the Flow Sheet corresponds with the
number of each reaction description and each step of
Example 1 which follow. Steps 5 through 3 represent
the novel process of this invention.
- 7 - 16643
1"~
CHO N;~
[~ CH3 S t 1 ~ C 3
3 CH3
~ Step 3 3 ~CN3
CH3
H3
_ 2
~ Step 4
~; ` /
3 0
~: .
~ : '
: ~ .,
: :`
::
'. : .
- ,
--8--
16643
~C02C~3
~CH ~ ~ CH3
~¦~Step 6
HO~--`Co2CH3 HO~a
C 3~ OH CH3
? Step 7 3, F~ ~ S~8
'3 ~3fU3
3 CH3
CH3~ Step 9
C' ~ -
H3
I I I
.' ' '
' ~ ' ' ': ' ' ` `
a.~
_ 9 _ 16643
REACTIONS IN THE E`LOW SHEET
1. Reaction with ani:Line in refluxing
toluene.
2. Reaction with Pal:Ladium (II) acetate in
acetic acid at reflux.
3. Reaction with a substituted Grignard
10 reagent CH3
F - ~ MgBr
in a suitable solvent such as benzene or toluene in
the presence of triphenylphoshine followed by
hydrolysis with 6N HCl at ambient temperature.
4. Aldol Reaction.
a) The classical Aldol synthesis in which
acetaldehyde is condensed with the starting
benzaldehyde, the resulting ~-hydroxyaldehyde is
acetylated with acetic anhydride and acetic acid is
eliminated thermally to give the corresponding
cinnamaldehyde.
b) The directed Aldol condensation in which
the anion of an appropriately N-substituted
ethylidenylimine, such as ethylidenecyclohexylimine
and the like, is condensed with the starting
- 10 - 16643
benzaldehyde at or below room temperature in an
aprotic solvent, such as THF and the like, to afford
a ~-hydroxy ~-phenyl-propylidenylimine which, upon
concomitant dehydration and imine hydrolysis in an
acidic medium, such as dilute aqueous HCl, provides
the corresponding cinnamaldehyde.
c) The use of a nucleophilic acetaldehyde
equivalent in which cis-2-ethoxyvinylithium,
generated from cls-l-ethoxy-2-tri-n-butylstannyl-
ethylene, is condensed with the starting benzaldehydeto give an allylic alcohol which is subse~uently
rearranged, under suitable acidic conditions, to the
corresponding cinnamaldehyde.
5. Dianion Step. Reaction with the dianion
of acetoacetic ester in a suitable aprotic solvent
such as THF, dioxane and the like.
6. Reduction with NaBH4 in a suitable
solvent such as methanol, ethanol and the like at or
below room temperature.
7. Lactonization. Saponification by base
(e.g. NaOH) in aqueous alcohol followed by
acidification and cyclodehydration by heating in
toluene followed by separation of the cis and trans
mixture by chromatogxaphy on silica gel or
crystallization.
8. Resolution of the trans racemate into
its enantiomers by treating the (+)-trans lactone
with either d-(+) or l-(~ -methylbenzylamine to
give the diastereomeric dihydroxy amides which are
separated by chromatography or crystallization.
:
~ 16643
3. Hydrolysis of each pure diastereomeric
amide under basic conditions, such as ethanolic NaO~
and the like to afford the corresponding enantiomer-
ically pure dihydroxy acid which, upon lactonization,
e.g., in refluxing toluene, provides the pure
(+)-trans enantiomer. Stereochernistry depends on the
absolute stereochemistry of the diastereomeric amide
from which it is derived.
A further aspect of the present invention is
a pharmaceutical composition consisting of compound
III in association with a pharmaceutical vehicle or
diluent. The pharmaceutical composition can be
formuated in a classical manner utilizing solid or
liquid vehicles or diluents and pharmaceutical
additives of a type appropriate to the mode of
desired administration. The compounds can be
administered by an oral route, for example, in the
form of tablets, capsules, granules or powders, or
they can be administered by a parent~ral route in the
form of injectable preparations. The dose to be
administered depends on the unitary dose, the
symptoms, and the age and the body weight of the
patient. A dose for adults is preferably between 200
and 2,000 mg per day, which can be administered in a
single dose or in the form of individual doses from
1-4 times per day.
A typical capsule for oral administration
contains active ingredient (250 mg), lactose (75 mg)
and magnesium stearate (15 mg). The mixture is
passed through a 60 mesh sieve and packed into a No. 1
gelatin capsule.
- 12 - 16643
A typical injectible preparation is pr~duced
by asceptically placing 250 mg of sterile active
ingredient into a vial, asceptically freeze-drying
and sealing. For use, the contents of the vial are
mixed with 2 ml of physiological saline, to produce
an injectible preparation.
The compound of this invention also has
useful antifungal activity. For example, it may be
used to control stralns of Penicilium sp.,
Aspergillus niger, Cladosporium sp. ! Cochliobolus
miyabeonus and Hilminthosporium cynodnotis. For this
utility it is admixed with suitable formulating
agents, powders, emulsifying agents or solvents such
as aqueous ethanol and sprayed or dusted on the
plants to be protected.
This invention can be illustrated by the
following examples in which ratios of solvents are in
volumes and percentages, unless otherwise indicated,
or by weight.
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EXAMPLE
(+)-(4R,6S)-(E)-6-[2-(4'-fluoro-3,3',5~trimethyl[1,1'-
biphenyl]-2-yl)-ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-
2H-pyran-2-one Step 1: Preparation of N-[(2,4-Dimethylphenyl)-
methylene]benzeneamine
A mixture of 2,4-dimethylbenzaldehyde (53.7
g, 0.4 mole), freshly distilled aniline (37.5 g, 0.4
mole) and toluene (150 ml) was heated at reflux under0 a Dean-Stark trap for 2 hours. The solution was
cooled and then concentrated under reduced pressure.
Distillation of the residue at 0.2 mm gave the
product as a yellow oil (81.3 g, 97~ yield), bp
122-130, which solidified on cooling.
Step 2: Preparation of Bis[~-(Acetato-O:O')bis(3,5-
dimethyl-2-[(phenylimino)methyl]phenyl-C,N]-
dipalladium
A mixture of N-[(2,4-dimethylphenyl)-
methylene]benzeneamine (58.7 g, 0.28 mole) and
palladium (II) acetate (62.9 g, 0.28 mole) in acetic
acid (1 L) was hea-ted at reflux with stirring for one
hour. After cooling (to 50), the reaction mixture
was filtered (gravity) and the filtrate poured into5 water (4 L). The aqueous mixture was stirred
overnight and then filtered. The collected solid was
washed with several portions of cold water, air dried
for several hours (with suction) and dried in a
vacuum oven ( 45) for 2 days to afford the desired
product as a yellow-orange solid (101.3 g, 97~ yield).
'7 ~ /~2~
- 1~ - 16643
Step 3: Preparation of 4'-Fluoro-3,3',5-trimethyl-
1,1'-biphenyl-2-carboxaldehyde
In a 1 L, 3-neck flask equipped with a
magnetic stirring bar, N2 inlet tube~ dropping
funnel (250 ml), and reflux condenser capped with a
drying tube, was placed Mg turnings 4.5 g (0.185
mole). This equipment was heated with a heat gun
under N2 and then allowed to cool to room
temperature. 5-Bromo-2-fluorotoluene (35.0 g, 0.185
mole) was dissolved in 300 ml of ether and 40 ml of
this solution was added to the Mg turnings. After
mild heating with a heat gun to initiate the
reaction, the remainder of the ether solution was
added at such a rate as to maintain reflux ( one
hour). The mixture was stirred at reflux for an
additional 30 minutes and cooled to room temperature.
Meanwhile, the Pd complex (45.2 g, 0.06
mole) from Step 2 had been added to 1 L of toluene
(3 L, 3-neck flask). The resulting mixture was
stirred vigorously and heated at reflux for one hour
using a Dean-Stark trap to collect traces of water.
The mixture was cooled to room temperature under
N2, triphenylphosphine (64.0 g, 0.24 mole) was
added and the mixture was stirred for 30 minutes.
The Grignard reagent was added b~ means of a dropping
funnel in a slow, steady stream and the reaction
mixture stirred for one hour. After addition of 200
ml 6N HC1, the mixture was stirred for an additional
one hour and filtered. The collected solid was
washed with several portions of toluene. The
filtrate and washings were combined and separated.
The toluene ether solution was washed with 2 x 200 ml
'7~Z~
- 15 - 16643
of brine and dried over MgSO4. Filtration and
evaporation yielded a black oil ( 70 g) which was
chromatographed using a 120 mm "Still" col~mn (1.5 kg
of 230-400 mesh Silica Gel) and 40~ (v:v) CH2C12-
hexane. There were collected 2 fractions o~ 1000 mland 20 fractions of 500 ml, the pure product being
~ound in fractions 5-14. Fractions 14-17 contained a
mixture of the desired aldehyde plus 2,4-dimethyl-
benzaldehyde. There was obtained 19-21 g of combined
product as a pale yellow solid ( 70~ yield); one
spot on tlc (Rf=0.30 on Silica Gel GF plate with
40% (v:v) CH2C12-hexane), mp 75-78C. The mp of
pure sublimed product is 78-80.
Step 4: Preparation of 3-(4'-Fluoro-3,3',5-trimethyl-
[l,l'~biphenyl]-2-yl)-2-~ro~enal
A dry 1 L, 4-neck flask equipped with a
magnetic stirring bar, N2 inlet tube, thermometer,
addition funnel (capped with a drying tube) and
septum was charged with a solution of (Z)-l-ethoxy-
2-tributylstannylethylene (68.5 g, 0.19 mole) in dry
THF (200 ml3 and then cooled in a dry ice-acetone
bath. n-Butyllithium (1.48 M in hexane, 130 ml, 0.19
mole) was added via syringe over a period of 25
minutes. The resulting mixture was stirred at -75
under N2 for one hour. A solution of 4'-fluoro-
3,3',5-trimethyl-1,1'-biphenyl-2-carboxaldehyde (40.7
g, 0.168 mole) in THF (150 ml) was added dropwise
( one hour) at -75. After stirring for 10 minutes,
the cooling bath was removed and the reaction mixture
was stirred at ambient temperature for 1-1/2 hours.
Saturated acl. NaHCO3 (150 ml) was added in a slow
2~
- 16 - 16643
steady stream and the mixture, distributed between
ether (500 ml) and water (500 ml). After separating
the layers, the aqueous phase was extracted with
ether (2x). The ether extracts were combined, washed
with cold water and brine, dried over MgSO4,
filtered and evaporated.
The residual oil was taken up in THF (200 ml)
and the solution treated with 6N HCl (25 ml) and
stirred at room temperature for one hour. The
mixture was diluted with cold water and extracted
(3x) with ether. The ether extracts were combined,
washed with cold water and brine, and dried over
MgSO4. Filtration and evaporation yielded a yellow
brown oil ( 120 g), which was chromatographed using
2.6 kg of Silica Gel (230-400 mesh) in a 140 mm
"Still" column. Elution with CH2C12-hexane t3:1,
v:v) gave 21 fractions (1 L each), the major portion
of product being located in fractions 11-19. After
evaporation, the oil was taken up in warm hexane
(60 ml); the solution was seeded and cooled at room
temperature to give a white crystalline solid
(20.6 g), mp 82-85. Fractions 9 and 10 were handled
separately and provided after recrystallization from
hexane an additional 3.6 g of product; total quantity
was 24.2 g (54~ yield).
Step 5: Preparation of Methyl (E)-7-(4'-fluoro-
3,3',5-trimethyl[l,l'-biphenyl]-2-yl) 5-
hydroxy-3-oxo-6-heptenoate
Methyl acetoacetate (12.31 g~ 0.106 mole)
was added dropwise to a stirred suspension of sodium
hydride (50~ oil suspension)(5.09 g, 0.106 mole) in
l .a, ~
- 17 - 16643
dry THF (180 ml) at 0 (internal, keeping
temperature 10C) and under N2. The resulting
solution was stirred at 0 for 15 minutes and then
treated with a solution of 1.40 M n-butyllithium in
hexane (78.7 ml, 0.106 mole) added dropwise ( 20
minutes) via syringe. After stirring at 0 for 20
minutes, the bath was replaced by an ice-acetone bath
and stirred for an additional 5 minutes. A solution
of 3-(4'-fluoro-3,3',5-trimethyl[l,l'-biphenyl]-
2-yl)-2-propenal (26.5 g, 0.099 mole) in dry THF (150
ml) was added dropwise ( 15 minutes) at such a rate
as to keep the temperature 10C. The reaction
mixture was stirred at 0C ~or 30 minutes and then
quenched by the slow addition of 6N HCl (45 ml). The
mixture was then diluted with water (300 ml) and
extracted (3x) with ether. The ether extracts were
combined, washed with cold water and brine, dried
(MgSO~), filtered and evaporated leaving a yellow
oil ( 38 g); one major spot on tlc (Silica Gel GF) at
Rf = 0.43 ~5% (v:v) acetone-CH2C12).
Step 6: Preparation of Methyl (E)-7-(4'-Fluoro-
3,3',5-trimethyl[1,1'-biphenyl]-2-yl)-3,5-
dihydroxy-6-heptenoate
Sodium tetrahydridoborate (1.92 g, 0.0507
mole) was added portionwise over a period of 10
minutes and with stirring to a cold solution (0C) of
methyl (E)-7-(4'-fluoro-3,3',5-trimethyl[l,l'-
biphenyl]-2-yl)-5-hydroxy-3-oxo-6-hep-tenoate (37.5 g)
in methanol (400 ml). The clear reaction mixture was
stirred at 0C for 15 minutes and then diluted with
water (300 ml). While maintaining the temperature
.'71.~4
- 18 - 16643
below 10C with an ice-bath, the mixture was
acidified with 12N HCl ( 22 ml). Following extrac-
tion with ether (3 x 250 ml), the ether extracts were
combined, washed with cold water and brine, dried
(MgSO4) and evaporated to a viscous oil ( 38 g).
The product showed one major spot on tlc (silica gel
GF) with Rf 0.21 (10% (v:v) acetone-CH2C12).
Step 7: Preparation of (+) trans (E)-6-[2-(4l-Fluoro-
-
3,3',5-trimethyl[l,l'-biphenyl]-2-yl)-
ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-2H-
pyran-2-one _ _
A solution of methyl (E)-7-(3'-fluoro-
3,3',5-trimethyl[l,l'-biphenyl]-2-yl)-3,5-dihydroxy-6-h
eptenoate ( 37.7 g, .0976 mole) and lN sodium
hydroxide (lO0 ml, 0.10 mole) in methanol (150 ml)
was stirred at room temperature for 15 minutes.
After removal of the methanol by evaporation ( 30),
the reaction mixture was diluted with water (600 ml),
acidified with conc. HCl and extracted with ether
(3 x 300 ml). The ether extracts were combined,
washed with cold water and brine, dried over MgSO~,
filtered, and evaporated to yield a yellow-orange oil
( 37 g)-
A solution of the crude oily diol acid in
toluene (300 ml) was heated at reflux under a Dean-
Stark trap for one hour. Evaporation provided a
yellow oil ( 37 g) which was a mixture of cis and
trans lactones. The crude product was chromatographed
using a 140 mm "Still" column (230-400 mesh Silica
Gel) and 10% (v:v) acetone-CH2C12. After
- . ,
- 19 - 16643
collecting 3 fractions of 1 L and 25 fractions of 500
ml, elution was continued with 20% (v:v) acetone-
CH2C12 collecting 6 fractions of 1 L each,
containing primarily cis racemate ( 84%). Fractions
12-15 of the 500 ml cuts were combined and evaporated
to give the trans racemate as a pale yellow oil ( 90%
pure by HPLC). This was crystallized from
Et2O-hexane to give a solid (5 g) mp 115-117.
Fractions 16-25 were combined and evaporated to give
a pale yellow oil ( 12 g), which was a (6:4) mixture
of trans and cls racemates.
This mixture ( 12 g) was re-chromatographed
in two runs with a Waters Prep LC500, employing 2
prep PAK-500 silica cartridges in series and eluting
15 with acetone-CH2C12 (1:9, v:v). Using the shave
recycle technique, the trans isomer (5 g) and the cls
racemate (4 g) were obtained. The samples of the
trans racemate, collected from the two
chromatographic separations, were combined to give a
20 white crystalline solid (10 g) mp 115-117. All cis
fractions from chromatography and the Waters
separation were combined to give 9 g which
crystallized on stand1ng.
Step 8: Preparation of (3R,5S)-N-((S)-~-Methyl-
benzyl)-7-(4'-fluoro-3,3',5-trimethyl[l,l'-
biphenyl]-2-yl)-3,5-dihydroxy-6-heptenamide
A solution of ~+)-trans-(E)-6-[2-(4'-fluoro-
3,3',5-trimethyl[l,l'-biphenyl]-2-yl)ethenyl]-3,4,5,6
30 tetrahydro-4-hydroxy-2H-pyran-2-one (10 g, 28.2 mole)
and (S)-(~ -methylbenzylamine (36.35 ml, 34.17 g,
282 mmole) in THF (35 mI) was stirred at gentle
:
. . . .
- 20 - 16643
reflux under N2 for 16 h. The reaction mixture was
then cooled, diluted wit Et2O (400 ml) and
successively washed with H2O (2 x 200 ml), 3N HCl
(2 x 300 ml) and brine (2 x 200 ml), dried (MgSO4)
and filtered. The filtrate was evaporated leaving
the mixture of intermediate d:iastereomeric amides as
a pale amber gum.
The residual gum was digested in Et2O (100
ml) and treated with hexane until turbid. This was
seeded and cooled at 0. Solid, 1.5 g, m.pO 110-12,
was collected by filtration. The filtrate was
evaporated to a gum ( 12 g).
This mixture of diastereomeric amides was
chromatographed using a Waters Prep LC500. Separa-
tion of the mixture was accomplished using two prepPAX-500/silica cartridges in series eluting with
methylene chloride-acetone (80:20, v:v). The mixture
was divided and run in two separate elutions. Using
the shave recycle technique, the two diastereoisomers
(1) (4.5 g, m.p. 110-12) and (2) (3.5 g, 52.6~ of
theory) m.p. 86-9 were obtainedO Compound (2) which
was 99~ pure by ~P~C is the desired diastereoisomer.
Mother liquors from recrystallization of (2) were
combined (1.9 g, 85~ (2)).
Ste~_9: Preparation of (+)-(4R,6S)-(E)-6-[2-(4'-
Fluoro-3,3',5-trimethyl[l,l'-biphenyl]-2-yl)-
ethenyl}-3,4,5,6-tetrahydro-4-hydroxy-2H-
pyran-2-one
A solution of N-((S)-~-methylbenzyl)-7-(4'-
fluoro-3,3'J5-trimethyl[l,l'-biphenyl]-2-yl)-3,5-di-
~1~7~L'Z~L
- 21 - 166~3
hydroxy-6-heptenamide (3.5 g, 7.35 mmol),
diastereoisomer (2) in step 8 above, in EtOH (300 ml)
containing lN NaOH (44 ml, 44 mmole) and H2O (44
ml) was refluxed under N2 for 14 h. The solvent
was removed ln vacuo ( 40). The residue was
dissolved in ice water (300 ml) and Et2O (500 ml),
then cooled and stirred at 0 while 3N HCl (50 ml)
was slowly added. The organic layer was separated
and washed successively with ice-cold lN HCl (200 ml)
10 and brine (2 x 200 ml), dried (MgSO4) and
filtered. After evaporation of solvent ln vacuo, the
remaining residue was dissolved in toluene (500 ml)
and refluxed under a Dean-Stark trap for 2 h.
Evaporation provided a yellow oil which was
15 chromatographed on a 50 mm "Still" column (230-400
mesh Silica Gel) using acetone-methylene chloride
(10:30, v:v) and collecting 10 ml fractions. The
product was found in cuts 19-31 followed by cuts
slightly contaminated with cis lactone. Less than
pure fractions were combined and, after evaporation,
further enriched by crystallization from Et2O-
hexane. The combined yield was 1.6 g, 61%. This was
99.99% pure by HPLC, m.p. ~7~9 E~]D5 + 40.56
(C = 1.075, CHC13).
.
