Note: Descriptions are shown in the official language in which they were submitted.
1051~79
SYNTHESIS OF ELYMOCLAVINE
AND DERIVATIVES
The present invention relates to the first syn-
thesis of a natural product, elymoclavine, by oxidation of
D-6-methyl-8-hydroxymethyl-lOa-methoxy-8-ergol~ene to for~
the corresponding D-8-aldehyde, followed by reduction.
Also, novel derivatives of 8-ergolenes are described
together with the processes for preparing them.
Compounds based on the ergoline ring system (I):
11~31~11 '.1
H- ~ I
have a surprising variety of pharmaceuticai activi-ties. For
example, lysergic and isolysergic acid are D-8-carboxy-
6-methyl-~9-ergolines (9,10-didehydroergolines or 9-ergo-
lenes.) The amides of lysergic acid have valuable andunique pharmacologic properties, and include the naturally
occurring peptide alkaloids; ergocornine, ergokryptine,
ergonovine, ergocristine, ergosine, and ergotamine, syn-
thetic oxytocic alkaloids such as methergine, and the syn-
thetic hallucinogen - lysergic acid diethylamide or LSD.
Ergotamine, a 9-ergolene, with a peptide side chain, has
been used in the treatment of migraine and recently, both
X-4292 - -2-
105187~
e~gocornine and 2-bromo-a-ergokryptine have been shown to
be inhibitors of prolactin and of dimethylbenzanthracene
(DMBA)-induced tumors in rats, according to Nagasawa
and Meites, Proc. Soc. Exp'tl. Bio. Med. 135, 469 (1970) and
to Heuson et al., Europ. J. Cancer, 353 (1970). (See also
U.S. Patents 3,752,888 and 3,752,814).
Non-peptide ergot derivatives, both naturally
occurring and totally or partially synthetic, share these
multiple pharmacological properties with the peptide deriva-
tives. For example, D-6-methyl-8-cyanomethylergoline was
prepared by Semonsky and co-workers, Coll. Czech. Chem.
Commun., 33, 577 (1968), and was found to be useful in
preventing pregnancy in rats - Nature, 221, 666 (1969) (See
also U.S. Patent 3,732,231) - by interfering with the secre-
tion of hypophysial leuteotropic hormone and the hypophysial
gonadotropins and by inhibiting the secretion of prolactin.
[See Seda et al., Reprod. Fert., 24 263 ~1971) and Mantle
and Finn, id. 441.] Semonsky and coworkers, Coll. Czech.
Chem. Comm., _, 220 (1971), have also prepared D-6-methyl-
8-ergolinylacetamide, a compound which is stated to have
anti-fertility and anti-lactating effects in rats. The
2-halo derivatives of D-6-methyl-8-cyanomethylergoline and
of D-6-methyl-8-ergolinylacetamide have been prepared and
tested for their prolactin inhibiting activity (M.J. Sweeney,
J.A. Celmens, E.C. Kornfeld and G.A. Poore, 64th Annual
Meeting Amer. Assoc. Cancer Research, April, 19731.
A number of the non-peptide indole alkaloids have
been found in fungus cultures grown on Elymus mollis and
other related grasses. These non-peptide alkaloids include
chanoclavine, agroclavine, elymoclavine, and penniclavine.
X-4292 -3-
1051879
Of particular interest are agroclavine, an 8-methyl-8-
ergolene; elymoclavine, an 8-hydroxymethyl-8-ergolene; and
penniclavine, a 8-hydroxymethyl-8-hydroxy-9-ergolene. These
non-peptide alkaloids have been shown to have potent rat
prolactin inhibiting activity comparable to that found with
the peptide alkaloid, ergocornine. The synthesis of pen-
niclavine from D-6-methyl-8-hydroxymethyl-lOa-methoxy-
ergolene has been disclosed by Bernardi and Temperilli at
the 9th Symposium on the Chemistry of Natural Products,
International Union of Pure and Applied Chemistry held at
Ottawa, Province of Ontario, Canada, June 24-28, 1974.
It is an object of this invention to provide a
synthesis of elymoclavine from optically active starting
materials. It is a further object of this invention to
provide useful 8-ergolene derivatives.
This invention relates to a process for the
preparation of novel ergolene compounds of the formula
~ \-
a1k-O~
~C 3
1~ ,~1, ,1 ( n:)
H ~
wherein R is formyl or -CH2OC-alk;
X-4292 - -4-
~05~879
and
alk is Cl-C3 alkyl,
which comprises reacting a compound of the formula
~H2H
alkO~ r
1~ ,1!, ,1
t ~ ~IV)
H~ - ~
wherein alk is Cl-C3 alkyl, with an agent selected from the
group consisting of:
a) an oxidizing agent to form the compounds
of formula (II) in which R is formyl; and
b) an acylating agent to form the compounds
o
of formula (II) in which R is -CH2OC~alk
A preferred compound of formula (II) is where R is
formyl. This compound is a novel intermediate in the first
synthesis of the natural product elymoclavine. The syn-
thesis of elymoclavine, having the formula
~H2H
~ \6/ ~ ~ 3
1~ "
H~ - ~ (V)
X-4292 -5-
1051879
comprises oxidizing a compound of formula (IV) to yield
the compound of formula (II) wherein R is formyl, namely,
~HO
a l k-O~ t
~CH
l~ ,q, ,I
t ~ (VI)
HN----
wherein alk is Cl-C3 alkyl, followed by reduction with a
reducing agent. This process provides elymoclavine in
excellent yield.
Examples of the Cl-C3 alkyl group include methyl,
ethyl, isopropyl and _-propyl.
The procedure of going from the primary alcohol
(IV) to the corresponding aldehyde (VI) can be carried out
with a variety of oxidative procedures. For example, sodium
dichromate in a mixture of pyridine hydrochloride and
pyridine, chromic oxide-pyridine complex in methylene
dichloride, potassium dichromate in aqueous sulfuric acid,
t-butyl chromate in benzene, nickel peroxide in benzene,
silver carbonate in benzene or silver oxide in phosphoric
and acetic acids, manganese dioxide in a variety of known
solvents, lead tetra-acetate in pyridine, sulfur trioxide-
pyridine complex in a mixture of dimethyl sulfoxide and
triethylamine, tetrachloro-1,2-benzoquinone (TCBQ) and
similar oxidation systems can all be employed [See Compen-
dium of Organic Synthetic Methods, Harrison and Harrison,
X-4292 -6-
1051~379
(John Wiley and Sons, Inc. r New York, 1971) Section 48 at
page 137-143.] We prefer to employ manganese dioxide in
chloroform or other suitable inert solvents as the oxidizing
agent to prepare the aldehyde (VI) from the primary alcohol
(IV). An alternate oxidizing procedure which gives simi-
larly excellent yields consists of using dicyclohexylcar-
bodiimide in a solvent consisting of a mixture of dimethyl-
sulfoxide, pyridine and trifluoroacetic acid. D-6-methyl-
8-formyl-lOa-methoxy-8-ergolene, formula (VI), can also be
prepared by contacting D-6-methyl-8-hydroxymethyl-lOa-
methoxy-8-ergolene in dimethylsulfoxide solution with a
mixture of pyridine and trifluoroacetic acid. Dicyclo-
hexylcarbodiimide is then added and the primary alcohol
group oxidized to an aldehyde according to the procedure of
Moffatt, J. Am. Chem. Soc., 89, 2697 (1967). D-6-methyl-
8-formyl-lOa-methoxy-8-ergolene prepared by this procedure
was purified by chromatography and crystallized.
The reduction of the &-formyl-lOa-alkoxy-8-
ergolene, formula (VI), with the concomitant elimination of
the lOa-alkoxy group can also be accomplished ~y a variety
of reagents. We prefer to employ an active metal in an
acidic medium as for example, zinc in acetic acid. Iron in
dilute hydrochloric acid can also be employed as can the
metal hydride reducing agents as exemplified by lithium
aluminum hydride and lithium aluminum (tri-t-butyloxy)
hydride. The term "active metal" used above in conjunction
with an acid medium and a reduction system, of course,
refers to those metals which are capable of displacing
X-4292 - -7-
'
105187~
hydrogen in acidic medium; the hydrogen being the reducing
substance. Reference to any table of standard oxidation-
reduction potentlals will indicate a large number of metals
which have a potential greater than the hydrogen-hydrogen
ion couple taken as zero. Included among these metals are:
iron, cadmium, cobalt, nickel, tin, zinc, aluminum and
sodium.
Treatment of a compound of formula (IV) with an
alkyl anhydride such as acetic anhydride, propionic an-
hydride or butyric anhydride yields the C-8 alkyl esters
o
of formula (II) wherein R is -CH20C-alk.
A lOa-ethoxy or lOa-propoxy derivative of formula
(IV) can be employed in place of D-6-methyl-8-hydroxymethyl-
lOa-methoxy-8-ergolene in any of the above processes. These
D-6-methyl-8-hydroxymethyl-lOa-alkoxy-8-ergolenes are
prepared by the reduction of a D-6-methyl-8-carbomethoxy-
lOa-alkoxy-8-ergolene as furnished by the procedure of U.S.
Patent 3,814,765. According to this procedure, methyl
lysergate is reacted with a mercuric salt, such as mercuric
acetate in a lower aliphatic alcohol for a period from 2-24
hours at a temperature from 0 to 50C. After the reaction
had been completed the excess salt is decomposed by the
addition of sodium borohydride. The 10~-alkoxy group will
be derived from the particular lower alkanol employed in the
mercuric salt reaction. The 8-carbomethoxy group is then
converted to the corresponding primary alcohol by reduction
with a metal hydride reducing agent preferably sodium
bis (2-methoxyethoxy) aluminum hydride.
X-4292 -8-
1051879
The compounds of formula (VI) are useful as a
novel intermediate in the synthesis of elymoclavine.
The compounds of formula (II) (with the exception
of those where R is formyl) are useful as prolactin in-
hibitors. The inhibition of prolactin secretion by the
compounds of formula (II) is evidenced by the following
experiment: Adult male rats of the Spraque-Dawley strain
weighing about 200 g. were used. All rats were housed in
an air-conditioned room with controlled lighting (lights
on 6 a.m. - 8 p.m.) and fed lab chow and water ad libitum.
In each experiment the rats were killed by decapitation,
and 150 ~1. aliquots of serum were assayed for prolactin.
Each male rat received an intraperitoneal injection of
2.0 mg. of reserpine in aqueous suspension 18 hours before
administration of the ergolene derivative. The purpose
of the reserpine was to keep prolactin levels uniformly
elevated. The derivatives were dissolved in 10~ ethanol
at a concentration of 10 mcg./ml., and were injected
intraperitoneally at a standard dose of 50 mcg./kg. Each
compound was administered to a group of 10 rats, and a
control group of 10 intact males received an equivalent
amount of 10 percent ethanol. One hour after treatment all
rats were killed by decapitation, and the serum was col-
lected and assayed for prolactin as previously described.
The results were evaluated statistically using Student's "t"
test to calculate the level of significance, "p". The
difference between the prolactin level of the treated rats
and prolactin level of the control rats, divided by the
prolactin level of the control rats gives the percent
X-4292 -9-
1051879
inhibition of prolactin secretion attributable to the
compounds of formula (II). The table which follows gives
prolactin inhibition percentages for a series of 8-ergo-
lenes of formula (II). In the table, column 1 gives the
name of the compounds; column 2, the dose level of the
compound in the prolactin inhibition test; column 3, the
percent prolactin inhibition; and column 4, the level of
significance.
X-4292 -10-
~51879
o
~,, o
,~
~ V
rl O
.,,
U
td r~ _~
--I Q t`
dP
~ a~ u~
E~ O
a O
_I
o
o .~,
C~
4~ ~
o U
G)
Z
X-4292
1051879
As prolactin inhibitors, the 8-ergolenes and
elymoclavine are useful in the treatment of inappropriate
lactation such as postpartum lactation and galactorrhea.
In addition, they can be used to treat prolactin-dependent
adenocarcinomas and prolactin-secreting pituitary tumors
as well as the following disorders: Forbes - Albright
syndrome, Chiari-Frommel syndrome, gynecomastia itself
and gynecomastia occurring as a result of estrogenic
steroid administration for prostatic hypertrophy, fibro-
cystic disease of the breast (benign nodules), prophylactictreatment of breast cancer, and breast development resulting
from the adminis*ration of psychotropic drugs, for example,
thorazine, or for prostatic hypertrophy itself.
In employing the compounds of formula (II) to
inhibit prolactin secretion, the compounds or a salt
thereof with a pharmaceutically-acceptable acid is sus-
pended in corn oil and the suspension injected parenterally
or fed to a female mammal in amounts varying from 0.01 to
10 mg./kg./day of mammalian weight. Oral administration
is preferred. If parenteral administration is used, the
injection is preferably by the subcutaneous route using
an appropriate pharmaceutical formulation although other
modes of parenteral administration such as intraperitoneal,
intramuscular, or intravenous administration are equally
effective. In particular, with intravenous or intramuscular
administration, a soluble pharmaceutically-acceptable salt
of the compound of formula (II) preferably the methanesul-
fonate or maleate salt, is customarily employed. For oral
administration, the compound either as the free base or in
the form of a salt thereof can also be mixed with standard
X-4292 -12-
1051879
pharmaceutical excipients and filled into empty telescoping
gelatin capsules or pressed into tablets.
This specification is further illustrated by the
following examples in which some of the terms are defined as
follows:
Van Urk test - reagent is composed of: 18 mg. of
ferric chloride; 0.5 g. of ~-dimethylaminobenzaldehyde; in
250 ml. of concentrated sulfuric acid and 140 ml. of water.
Equal volumes of reagent and test solution are prepared;
color formed is blue or green when an ergolene having no
substituent in the 2-position is present.
nmr - nuclear magnetic resonance, measured in
parts per million l~).
W - ultraviolet, measured in millimicrons (m~).
and ~ is molar absorptivity.
Example 1
A solution containing 515 mg. of D-6-methyl-8-
hydroxymethyl-lOa-methoxy-8-ergolene in 150 ml. of chloro-
form was prepared. Four g. of manganese dioxide were added
and the reaction mixture stoppered and stirred at room
temperature for one-half hour. The reaction mixture was
filtered, and the filter cake washed with chloroform.
Evaporation of the filtrate to dryness yielded a residue of
D-6-methyl-8-formyl-10~-methoxy-8-ergolene. The residue was
chromatographed over 30 g. of "Florisil"* using chloroform
containing 1 to 2 percent methanol as the eluant. Fractions
shown to contain the 8-formyl compound by thin layer
chromatography were combined and the solvent evaporated
therefrom. Recrystallization of the resulting residue
*Trademark for an activated magnesium silicate, in the form of
hard, porous granules, employed in chromatography.
-13-
~" " .
lOS~879
yielded purified D-6-methyl-8-formyl-lOa-methoxy-8-ergo-
lene melting at 196-7C. with decomposition. Yield of 65
Analysis on C17H18N202
(percent) Calc.: C, 72.32; H, 6.43; N, 9.92;
Found: C, 72.07; H, 6.20; N,-9.65.
nmr (CDC13):
2.57 (s, ~N-CH3)
3.15 (s, -OCH3)
7.70 (s,~ =C~H)
8.77 (b, indole NH)
O
9.72 (s, -C-H)
Example 2
A solution containing 505 mg. of D-6-methyl-8-
hydroxymethyl-lOa-methoxy-8-ergolene in 25 ml. of dimethyl-
sulfoxide with a mixture of 0.15 ml. of pyridine and 0.22
ml.- of trifluoroacetic acid was prepared. 1.2 g. of di--
cyclohexylcarbodiimide was then added to the solution. The
solution was stirred for 1 1/4 hours at room temperature
under nitrogen, then poured into aqueous tartaric acia and
filtered. The filtrate was extracted with chloroform. The
organic layer was discarded. The aqueous layer was made
basic with ammonium hydroxide and extracted with ethyl
acetate until the extract gave a negative Van Urk test. The
organic solution was washed with water, then with saturated
sodium chloride, and dried over sodium sulfate. The re-
sulting residue was comprised of D-6-methyl-8-formyl-lOa-
X-4292 -14-
1051879
methoxy-8-ergolene. Yield of 89%. This product was iden-
tical with that obtained in Example 1.
Example 3
A solution was prepared containing 300 mg. of
D-6-methyl-8-formyl-lOa-methoxy-8-ergolene in 25 ml. of
acetic acid. Two g. of zinc dust were added and the
reaction mixture stirred at room temperature for 45 minutes.
The reaction mixture was filtered and the filtrate poured
over ice. The aqueous layer was made strongly basic with 10
percent aqueous ammonium hydroxide, and the alkali-insoluble
organic material extracted with chloroform. The chloroform
extractions were continued until a chloroform extract showed
a negative Van Urk test. The chloroform extracts were
combined and washed with saturated aqueous sodium chloride.
Evaporation of the organic solvent yielded elymoclavine.
Yield of 50%
UV in ethanol --
m~. _
292 5,320
282 6,170
277 6,000
22525,090; and
~ass spectrum was identical to known
elymoclavine from Norich Chemical Company
Example 4
A solution was prepared containing 865 mg. ofD-6-methyl- -formyl-lOa-methoxy-8-ergolene in 150 ml. of
tetrahydrofuran (THF). One g. of lithium aluminumhydride
was added thereto in portions. After the addition had been
X-4292 -15-
1051879
completed, the reaction mixture was stirred at room tempera-
ture under a nitrogen atmosphere for one hour. Next, a
solution of 1 g. of aluminum chloride in 50 ml. of THF was
added in dropwise fashion. Again, after the addition had
been completed, the reaction mixture was diluted with water,
and the aqueous layer extracted with chloroform until a
chloroform extract showed a negative Van Urk test. The
chloroform extracts were combined, washed with saturated
sodium chloride and dried, and the solvent evaporated.
Recrystallization of the resulting residue from methanol
yielded a 50:50 mixture of elymoclavine and lysergol,
separable by chromatography. The analysis of the mixture
was
(percentl Calc.: C, 75.56; H, 7.13; N, 11.01;
Found: C, 75.37; H, 7.35; N, 10.72.
Example 5
A solution was prepared containing 2.3 g. of
D-6-methyl-8-hydroxymethyl-lOa-methoxy-8-ergolene in 100 ml.
of pyridine. Ten ml. of acetic anhydride were added; the
reaction mixture was stirred at room temperature for 1.5
hours and was then poured into an ice-10 percent aqueous
ammonium hydroxide mixture. 6-Methyl-8-acetoxymethyl-lOa-
methoxy-8-ergolene formed in the above reaction was in-
soluble in the aqueous alkaline layer and was extracted with
ethyl acetate. The ethyl acetate extract was separated,
washed with water followed by saturated aqueous sodium
chloride and then dried. E~aporation of the ethyl acetate
yielded a residue comprising D-6-methyl-8-acetoxyme'.hyl-
lOa-methoxy-8-ergolene which was crystallized from ether;
m.p. = 180C. with decomposition.
X-4292 -16-
1~51879
Analysis on ClgH22N203
(percent) Calc.: C, 69.92; H, 6.79; N, 8.58;
Found: C, 69.71; H, 6.54; N, 8.39.
X-4292 -17-
