IE41475B1 - Improvements in or relating to ergolene derivatives - Google Patents

Abstract

Ergolenes of the following formula in which R is the formula radical and alk is C1-C3-alkyl are prepared. These compounds are obtained by oxidising a corresponding 6-methyl-8-hydroxymethyl-10 alpha -alkoxy-8-ergolene. The resulting compounds are suitable for preparing elymoclavine by reducing the compound of the formula II. The said elymoclavine can be used as prolactin inhibitor.

Description

This invention relates to the synthesis of ergolene derivatives, to novel ergolene compounds and to pharmaceut ical formulations containing such compounds.

Compounds based on the ergolene ring system (I): H-NJL_2 (I) have a surprising variety of pharmaceutical activities.

For example, lysergic and isolysergic acid are D-8-carboxy ergolenes). The amides of lysergic acid have valuable and unique pharmacologic properties, and include the naturally occurring peptide alkaloids? ergocornine, ergokryptine, ergonovine, ergocristine, ergosine, and ergotamine, synthetic oxytocic alkaloids such as methergine, and the synthetic 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 ergocornine 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 - 3 41475 (1970) and to Heuson et al., Europ. J. Cancer, 353 (1970). (See also U.S. Patents 3,752,388 and 3,752,814).

Non-peptide ergot derivatives, both naturally occurring and totally or partially synthetic, share these multiple pharmacological properties with the peptide derivatives.

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 secretion of hypophysial leuteotropic hormone and the hypophysial gonadotropins or by inhibiting the secretion Of prolactin.

[See Seda et al., Reprod. Fert., 24, 263 (1971) and Mantle and Finn, id. 441]. Semonsky and co-workers. Coll. Czech. chem. Comm., 36, 220 (1971), have also prepared D-6-methyl8-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, 1973).

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, argoclavine, elymoclavine, and penniclavine. Of particular interest are agroclavine, an 8- methyl-8-ergolene; elymoclavine, an 8-hydroxymethyl-830 ergolene; and penniclavine, an 8-hydroxymethyl-8-hydroxy9- ergolene. These non-peptide alkaloids have been shown to have potent rat prolactin inhibiting activity comparable - 4 to that found with the peptide alkaloid, ergocornine. The synthesis of penniclavine from D-6-methyl-8-hydroxymethylΙΟα-methoxyergolene 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.

This invention relates to ergolene compounds of the formulae wherein R is Ii -CH^OC-alk and either R^ is hydroxymethyl and R2 is II alk—C —0_ or alk-S-, or R^ and R2 taken together form a methylene acetonide, the term aik representing a C^-C alkyl group.

The compounds of formula (II) can be prepared by reacting a compound of the formula wherein alk is C^-C.^ alkyl, with an acylating agent to form a compound of formula (II) in which R is O II —CKhjOC—alk , said acylating agent being an alkanoic acid anhydride.

The cq~C2 alkyl groups are methyl, ethyl, isopropyl and n-propyl.

Treatment of a compound of formula (IV) with an alkanoic acid anhydride such as acetic anhydride, propionic anhydride or butyric anhydride yields the C-8 alkyl esters of formula (II) wherein R is II —CH2OC-alk .

The compounds of formula (III) can be prepared by reacting a compound of the formula wherein alk is C^-Cg alkyl, with a) an acylating agent using standard allylic rearrangement conditions in the presence of a mineral acid to form the compounds of formula (III) in which Rj is II alk—C—0— ; or t>) an alkyl mercaptan in the presence of a Lewis acid to form the compounds of formula (III) in which R^ is alk-S-.

The allylic rearrangement of the 8-hydroxymethyl-10a alkoxy compound (IV) to yield penniclavine (formula (III) where R_> is hydroxy) or a penniclavine acylate (formula (III) where R2 is II alk — C —0 — is carried out under standard allylic rearrangement conditions employing an acid. The medium in which the rearrangement takes place in general determines the nature of the C-8 group; that is to say, the predominant species - 7 in the solvent will determine the nature of the radical. For example, if the reaction is carried out in a propionic acid medium, the product of the reaction will be an 8apropionyloxy derivative. If a predominantly aqueous medium is used, the reaction product is the known product, penniclavine.

Penniclavine can be readily transformed to an acetonide (formula (III) wherein and R2 taken together form a methylene acetonide) by treatment with acetone in the presence of acid.

The compounds of formula (IV) can also be transformed to yield the 8a-alkylmercapto ethers related to penniclavine and represented by formula (III) wherein R2 is alk-S-.

These compounds are prepared by treating compound (IV) with an alkylmercaptan (alk-SH) in the presence of a Lewis acid such as boron trifluoride.

A Ιθα-ethoxy or 10a-propoxy derivative of formula (IV) can be employed in place of D-6-methyl-8-hydroxymethyl10a-methoxy-8-ergolene in any of the above processes.

These D-6-methyl-8-hydroxymethyl-10ct-alkoxy-8-ergolenes are prepared by the reduction of a D-6-methyl-8-carbomethoxy-10ct-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 c^_3 alkanol for a period from 2-24 hours at a temperature from 0° to 50°C. After the reaction had been completed the excess salt is decomposed by the addition of sodium borohydride. The 10a-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 - 8 hydride.

Also included within the scope of this invention are the non-toxic salts of the ergolene bases represented by formula (III) above when is alk-S- or and Rg taken together form a methylene acetonide. These non-toxic salts can be formed with both organic and inorganic pharmaceutically -acceptable acids. Such salts include sulfates, such as sulfate, pyrosulfate, and bisulfate; sulfites, such as sulfite and bisulfite; nitrate; phosphates, such as phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate and pyrophosphate; halides, such as chloride, bromide and iodide; C^-C., aliphatic carboxylates, such as / acetate, propionate, decanoate, caprylate, acrylate, formate, isobutyrate, caprate, heptanoate and propiolate; C-^-C-j-O aliphatic dicarboxylates, such as oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, butyne1,4-dioate and hexyne-1,6-dioate; benzoates, such as benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate and methoxybenzoate; phthalates, such as phthalate and terephthalate; arylsulfonates, such as toluenesulfonate and xylenesulfonates; citrate; C2~C5 α-hydroxy-alkanoates, such as lactate, a-hydroxybutyrate and glycollate; α-hydroxyalkanedioates, such as malate and tartrate; and C^-C.^ alkyl sulfonates, such as methanesulfonate and propanesulfonate.

The compounds of formulae (II) and (III) are useful as prolactin inhibitors.

According to a further aspect of the invention there is provided a pharmaceutical formulation comprising as an active ingredient an ergolene of formula (II) or (III), or a pharmaceutically-acceptable salt thereof, associated with a pharmaceutically-acceptable carrier therefor. 41478 - 9 The inhibition of prolactin secretion by the compounds of formulae (II) or (ill) is evidenced by the following experiment: Adult male rats of the Sprague-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 U-l. 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 meg./ml., and were injected intraperitoneally at a standard dose of 50 meg./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 collected and assayed for prolactin as previously described. The results were evaluated statistically using Student1s 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 inhibition of prolactin secretion attributable to the compounds of formulae (II) and (ill). The table which follows gives prolactin inhibition percentages for a series of 8- and 9-ergolenes of formulae (ll) and (ill). In the table, column 1 gives the name of the compounds? column 2, the dose level of the compound in the ptolactin inhibition test; column 3, the percent prolactin inhibition; and column 4, the level of significance.

TABLE Name of Compound Dose % Prolactin Inhibition p Value penniclavine acetonide 10 meg. 56 <.001 elymoclavine 10 meg. 71 <.001 penniclavine 10 meg. 40 <.05 As prolactin inhibitors, the 8- and 9-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, fibrocystic disease of the breast (benign nodules), prophylactic treatment of breast cancer, and breast development resulting from the administration of psychotropic drugs, for example, thorazine, or for prostatic hypertrophy itself. in employing the compounds of formulae (II) and (III) to inhibit prolactin secretion, the compounds or a salt thereof with a pharmaceutically-acceptable acid is suspended 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 intra30 peritoneal, 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) or (III), preferably the methanesulfonate 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 pharmaceutical excipients and filled into empty telescoping gelatin capsules or pressed into tablets.

This invention 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 p-dimethylaminobenzaldehyde; in 250 ml. of concentrated sulfuric acid and 140 ml. of water. Equal volumes of reagent and test solution are prepared, colour 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 (δ).

UV - ultraviolet, measured in millimicrons (ζημ.), and ε is molar absorptivity.

Example 1 A solution was prepared containing 2.3 g. of D-6methyl-8-hydroxymethyl-10a-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-10a-methoxy-8-ergolene formed in the above reaction was insoluble 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. Evaporation of the ethyl acetate yielded a residue comprising D-6-methyl41475 8-acetoxymethyl-10a-methoxy-8-ergolene which was crystallised from ether; m.p. = 180°C, with decomposition.

Analysis of clgH22N203 (Percent) Cale.; C, 69.92; H, 6.79; N, 8.58; Found : C, 69.71; H, 6.54; N, 8.39.

Example 2 A solution of 535 mg. of D-6-methyl-8-hydroxymethyll0a-methoxy-8-ergolene in 50 ml. of acetic acid wag prepared, and the solution stirred at room temperature under a nitrogen atmosphere for 1 hour. The reaction mixture was then poured onto ice, and the resulting aqueous solution made basic with dilute ammonium hydroxide. Extraction of the alkaline layer with chloroform was continued until a negative Van Urk test was obtained. The chloroform extracts were combined, washed with saturated aqueous sodium chloride and dried. Evaporation of the chloroform yielded a residue which was redissolved in chloroform and the chloroform solution chromatographed over florisil (Trade Mark) using chloroform containing 1 percent methanol as the eluant. Fractions shown by thin layer chromatography to contain D-6-methyl-Sp-hydroxymethyl8a-acetoxy-9-ergolene formed in the above reaction were combined, the solvent evaporated therefrom, and the residue recrystallised from ethanol. D-6-methyl-8p-hydrOxymethyl8a-acetoxy-9-ergolene thus purified melted at 154-5°C. with decomposition.

Analysis on cqgHlgN2°3 (percent) Calc, t C, 69.21; H, 6.45; N, 8.97; Pound : C, 69.49; H, 6.35; N, 8.86.

Example 3 A solution containing 525 mg. of D-6-methyl-8-hydroxy- 13 methyl-10a-methoxy-8-ergolene in 25 g. of methylmercaptan was stirred for one-half hour at 0-10°C. One ml. of borontrifluoride etherate was adc}ed, and the stirring continued at the same temperature for an additional hour.

At this point, all the ingredients were not in solution and 25 ml. of tetrahydrofuran were added. The reaction mixture was stirred for an additional hour and then diluted with water. The resulting aqueous layer was made basic with dilute ammonium hydroxide, and the alkaline layer extracted with chloroform until an extract showed a negative Van Urk test. The chloroform extracts were combined and washed with saturated aqueous sodium chloride. The chloroform was evaporated. The resulting residue was redissolved in chloroform and chromatographed over florosil using chloroform containing 0-1 percent methanol as the eluant. Fractions shown by thin layer chromatography to contain D-6-methy-8β-hydroxymethyl-8cz-methylmercapto-9ergolene prepared in the above reaction were combined and recrystallised from ether; m.p. 16O-2°C. with decomposition. Analysis on C^H^NgOS (percent) Calc, s C, 67.97; H, 6.76; N, 9.32; S, 10.67; Found : C, 68.08; H, 6.83; N, 9.07; S, 10.92.

Earlier fractions were shown by thin layer chromatography to contain both D-6-methyl-8p-hydroxymethyl-8amethylmercapto-9-ergolene and its 8a-hydroxymethyl-8pmethylmercapto isomer. This latter compound is slightly less polar than D-6-methyl~8a-hydroxymethyl-8p-methylmercapto-9-ergolene, and the mixture can be separated by chromatography.

Example 4 A solution was prepared containing 1.94 g. of D-6methyl-8-hydroxymethyl-10a-methoxy-8-ergolene in 250 ml. of 2 percent aqueous tartaric acid. The reaction mixture was kept under a nitrogen atmosphere at room temperature for about 3 days, and was then made basic with 10 percent aqueous ammonium hydroxide. Penniclavine, formed in the above reaction, was insoluble in the alkaline layer and was extracted into chloroform. The chloroform extractions were continued until a negative Van Urk test was obtained. The chloroform extracts were combined, washed with saturated aqueous sodium chloride and dried. Evaporation of the chloroform left as a residue penniclavine which was further purified by dissolution in chloroform and chromatographing the chloroform solution over 190 grams of florisil The penniclavine was eluted with chloroform containing 3-7 percent methanol. The development of the chromatogram was followed on thin layer chromatography, and fractions shown to contain penniclavine by this technique were combined and the solvent evaporated therefrom to yield penniclavine as a residue. Recrystallisation of the penniclavine from chloroform gave crystalline material melting at 212-214°C.

Analysis on cigHig°2N2 (percent) Calc. : C, 71.09; H, 6.71; N, 10.36; Found ; C, 70.85; H, 6.44; N, 10.08.

A solution was prepared containing 290 mg. of penniclavine in 150 ml. of acetone. 0.3 ml. of 70 percent aqueous perchloric acid was added: the reaction mixture was stoppered and stirred at room temperature for about 2 hours, and was then poured into aqueous ammonium hydroxide. The organic material was extracted from the alkaline layer with ethyl acetate. The ethyl acetate layer was separ30 ated, washed with water and with saturated aqueous sodium chloride and then dried. Evaporation of the organic solvent yielded a residue comprising penniclavine acetonide.

The residue was dissolved in chloroform and chromatographed over florisil using chloroform containing 2 percent ethanol as the eluant. Fractions shown to contain penniclavine acetonide by thin layer chromatography were combined and recrystallised from ethanol. Penniclavine acetonide, D-6methyl-8p-hydroxymethyl-8a-hydroxy-9-ergolene acetonide, thus prepared melted at 26O°C. with decomposition.

Analysis on c19h2iN2°2 (percent) Calc. : C, 73.52; H, 7.14; N, 9.03; Found : C, 73.23; H, 6.91; N, 8.80.

Claims (11)

1. An ergolene of the formula: wherein R is

2. D-6-methyl-8-acetoxymethyl-l0a-methoxy-8-ergolene;

3. D-6-methyl-8P-hydroxymethyl-8a-acetoxy-9-ergolene;

4. D-6-methyl-8p~hydroxymethyl-8a-methylmercapto-9ergolene; 15 5. D-6-methyl-8P~hydroxymethyl-8a-hydroxy-9-ergolene acetonide.

5. (III) in which R 2 is II alk—C—0— ; or b) an alkyl mercaptan in the presence of a Lewis acid to form a compound of formula (III) in which R 2 is alk-S-. 5 — CH 2 OC —alk and either R^ is hydroxymethyl and Rj is II alk—C—0 — or alk-S-, or R^ and R 2 taken together form a methylene acetonide, the term alk representing a C^-C^ alkyl group;

6. An ergolene of formula II or III according to claim 1, substantially as hereinbefore described.

7. A process for the preparation of an ergolene of 20 the formula II as shown in claim 1 wherein R and alk are defined as in claim 1, which comprises reacting a compound wherein alk is defined as in claim 1, with an acylating 5 agent to form a compound of formula (II) in which R is II —CHJ3C—alk , said acylating agent being an alkanoic acid anhydride.

8. A process for the preparation of an ergolene of the formula III as shown in claim 1 wherein R^ is hydroxy10 methyl and R 2 is II alk—C—0— or alk-S-, the term alk representing a C^_ 3 alkyl group, which comprises reacting a compound of the formula (IV) wherein alk is defined as in claim 1 with a) an acylating agent using standard allylic rearrangement conditions in the presence pf a mineral acid to form a compound of formula

9. A process for preparing a compound according to claim 1 substantially as hereinbefore described with reference to any one of the Examples.

10. An ergolene of formula (II) or (III) whenever prepared by a process according to claim 7, 8 or 9. 10 or a pharmaceutically-acceptable salt thereof.

11. A pharmaceutical formulation comprising as an active ingredient an ergolene of formula (II) or (III) as claimed in any one of claims 1 to 6 or 10, or a pharmaceut ically-acceptable salt thereof, associated with a pharmaceutically-acceptable carrier therefor.