PT99888A - PROCESS FOR THE PREPARATION OF MILBEMICINES AND AVERMECTINS WITH ANTELMINTIC ACTIVITY - Google Patents

Description

The present invention relates to novel anthelmintic compounds, processes for their production, pharmaceutical formulations containing them, and their use in human or veterinary medicine.

Milbemycins and avermectins are a group of macrolide antibiotics that have been prepared by culturing microorganisms and are described in inter alia GB-A-1,390,336, J. Antibiotics 29 (3), 76-14 to 76-16 and 29 (6), 76-35 to 76-42, GB-A-2 170 499, EP-A-0 073 660 and EP-A-0 204 421. They exhibit anthelmintic activity. Milbemycins and antihelmintic active avermectins are further described in GB-A-2 176 180, EP-A-0 212 867, EP-A-0 237 339, EP-A-0 241 146, EP-A-0 214 731 , EP-A-0 194 125, EP-A-0 170 006, and US-A-4,285,963.

The compounds shown in the foregoing references include compounds of formula (A): >

Rc (A), b * wherein Ra is methoxy or hydroxy, R " is hydrogen, Rc is pentanoyloxy, heptanoyloxy, or 2-methylhexanoyloxy, and R is methyl or ethyl; or

R 2 is methoxy or hydroxy, R 2 is hydrogen, R 2 is methyl-butanoyloxy,

2,4-dimethylpent-2-enoyloxy, or 2,4-dimethylpentanoyloxy, and Ra is methyl or ethyl, with the proviso that when R is ethyl, R is hydroxy and Rc is 2,4- dimethylpentanoyloxy; or Ra is methoxy or hydroxy, R6 is the group of the formula:.

(4 '- (Î ± -L-oleandrosyl) -α-L-oleandrosyloxy), RC is hydroxy, and R1 is 1-methyl propyl. EP-A-0 325 462 (USSN 299,933) discloses the compound of formula (B), which has been designated VM48130; > ocochCcv ^^

The absolute configuration of the compounds of the formulas (A ') and (B) is thought to be as follows:

The present invention provides compounds of the formula

(I)

Wherein R is optionally hydroxy or methoxy protected, R is hydrogen or 4 - (α-L-oleandrosyloxy and -Y- is a C1-4 alkylene group optionally substituted by one or more organic radicals.

i v 6%

"

Suitable hydroxy protecting groups include TBDMS (t-butyldimethylsilyl), and acyl. Other suitable protecting groups are described in, for example, " Protective Groups in Organic Synthesis " Theodora W. Greene, Wiley-Interscience 1981 Ch 2, 10-86. 1 2

Preferably, R is hydroxy and R is hydrogen.

Organic radicals may advantageously be selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heterocyclyl, mono-, bi- and tri-cycloalkyl, mono-, bi- and tri-cycloalkenyl and aralkyl. 1-20

As used herein the term alkyl includes straight and branched, more especially particularly C _6 alquilo alkyl, and alkenyl and alkynyl include straight and branched C₂₂,, more especially alkenyl and alkynyl. The alkylene group Y, or a said alkyl, alkenyl or alkynyl moiety, including the moieties as optional substituents on Y, may optionally be substituted by one or more substituents selected from the group consisting of hydroxy, alkoxy, alkylthio, oxo, halogen, trifluoromethyl, and optionally substituted amino.

When used herein the term " aryl " includes phenyl and naphthyl optionally substituted with up to five, preferably up to three, groups selected from halogen, C1-6 alkyl, aryl, C1-6 alkoxy, C1-6 alkyl substituted by halo, hydroxy, amino, nitro, carboxy, C1-6 alkoxycarbonyl, C1-6 alkoxycarbonyl- (C1-6) alkyl, C1-6 alkylcarbonyloxy, or C1-6 alkylcarbonyl. > '. 7

-ST - The expression " heterocyclyl " includes saturated, unsaturated and aromatic single or mixed rings comprising up to four hetero ring atoms selected from oxygen, nitrogen and sulfur and optionally substituted with up to three halogen, C1-6 alkyl, alkoxy / halo- (C1-6) alkyl groups; alkyl, hydroxy, amino, carboxy, C _ alco alco alkoxycarbonyl, C alco alkoxycarbonyl-1-6 nyl (C 1-6) alkyl, aryl or oxo.

Suitably the heterocyclic ring comprises 4 to 7 ring atoms, preferably 5 to 6 atoms.

The term " halogen " refers to fluoro, chloro, bromo and iodo.

As used herein, mono-, bi- and tri-cycloalkyl include especially C 3-12, especially C 3-8, groups and C 4-8 cycloalkenyl, and mono-, bi- and tri-cycloalkenyl groups include C 4 -20, especially C 4-8 groups, especially when any radical organic moiety comprises a mono-, bi- or tri-cycloalkyl or mono-, bi- or tri-cycloalkenyl moiety, the moiety may be substituted as indicated above by alkyl alkenyl, and alkynyl, and / or by one or more selected substituents of the group consisting of methylene and alkyl. Bicyclic and tricyclic groups may be joined or bridged and are preferably attached by means of a carbon atom which is common to two rings.

Any two substituents on -Y- may be taken together with the carbon atom (s) to which they are attached to designate a cycloalkyl, cycloalkenyl, aryl or heterocyclyl group which may optionally be substituted as indicated above. The compound or mixture of compounds according to the invention is suitably provided in a substantially pure form, for example at least 50% purity, suitably at least 60% purity, advantageously at least 75% purity, especially less with 98% purity, all percentages being calculated as weight / weight. An impure or less pure form of a compound according to the invention may, for example, be used in the preparation of a more pure form of the same compound or a related compound (for example a corresponding derivative) suitable for pharmaceutical use.

The compounds of the invention have parasiticidal properties, for example against nematodes such as Trichostronavlus colubriformis. and are useful for the treatment of helminthase in animals such as mammals, including humans and domestic animals (including farm animals).

Accordingly the present invention also provides a compound according to the invention, for use in the treatment of the human or animal organism, especially for the treatment of endo- and ectoparasitic infestations and particularly for the treatment of helminthiasis of domestic animals and crops. The term helminthase encompasses diseases of humans and animals caused by infestation with parasitic worms such as Strongyles, Ascarids, hookworms, pulmonary worms, filaria worms and Spodoptera littoralis. The compound may also be used against nematodes occurring in the soil or parasitizing plants.

The compounds of the invention are also active against Arthropods. The phylum Arthropoda comprises insects - such as flies, lice, bedbugs, beetles and fleas - and arachnids - such as mites and ticks.

Thus, a broad aspect of the invention provides a method for eradicating infestations by arthropods or nematodes, which method comprises applying a compound according to the invention or a derivative thereof to arthropods or nematodes or their environment. The present invention thus provides a pesticidal composition comprising a compound according to the invention or a derivative thereof together with a suitable carrier or excipient, such as an aerosol formulation. The present invention also provides a pharmaceutical or veterinary composition comprising a compound according to the invention or a pharmaceutically acceptable derivative thereof together with a pharmaceutically or veterinarily acceptable carrier or excipient. The present invention also provides a method of treating or prophylaxis of endo- and ectoparasitable infestations, especially helminthiasis, of animals (including birds and fish), especially of humans and domestic maize, comprising administering a quantity non-toxic composition of a compound according to the invention or a pharmaceutically acceptable derivative thereof, or a composition according to the invention, to a patient in need thereof. The composition according to the invention may be formulated for administration in any convenient manner for use in human or veterinary medicine, by analogy with other anthelmintics.

In suitable formulations the drug may be administered to animals orally (in the form of a paste, water, bolus, capsule or tablet), parenterally, percutaneously, as a food additive (for example granules, pills or powder), or may be prepared in the form of an aerosol spray.

The compounds of the invention may be formulated as a mixture with each other and / or with other anthelmintics, insecticides, acaricides or other pharmacologically active substances.

Suitably the composition consists of sufficient material to provide a dose ranging from 0.001 to 100 mg of active ingredient per kg of animal body weight per dose, more suitably 0.01 to 10 mg / kg per dose. a composition according to the invention may suitably contain from 0.1% by weight, preferably from 1.0 to 60% by weight, of the compound according to the invention (based on the total weight of the composition), depending on the method administration.

It will be appreciated that in some instances it will be advisable to repeat the dosage of the infected or potentially infected human or animal with the compound of the invention according to standard dosage regimens used with anthelmintics.

Compounds of formula (I) may be prepared by treatment of a compound of formula (II):

Wherein R 1 and R 2 are as defined above, with a compound of the formula XYX, wherein X and X are the same or different and each is a leaving group, or, in the case where Y is 1-methylene X and X, together with the carbon atom to which they are attached, form a carbonyl group, and R e is hydrogen or C g g alquilo alkyl. The reaction is typically performed at ambient temperature in an organic solvent such as dichloromethane in the presence of an appropriate acid catalyst such as p-toluenesulfonic acid.

Suitable leaving groups include C1-6 alkoxy.

Compounds of formula (II) may be obtained from compounds of formula (III):

OH

in which R is C25 substituent of an avermectin or milbemycin, such as those indicated above for compounds of the formulas (A) and (B), as indicated below:

(i) NaI04 / MeOH / RT (ii) NaBH4 / 0 ° C 4

It will be appreciated that the substituent -OR at the C21 position is part of an acetal group. So it can be trade-off. . 4 4 + by other substituents -0R by treatment with HOR / H.

Compounds of the formula (III) occur naturally or may be obtained from naturally occurring compounds, such as compounds of the formulas (A) and (B), by hydrolysis of an acyloxy substituent at the C23 position. The acyloxy group may be hydrolyzed by conventional methods such as basic hydrolysis for example NaOH / MeOH, enzymatically using hydrolase, or by treatment with a suitable hydride reducing agent for example diisobutylaluminium hydride (DIBAL).

It will be appreciated that the process of the invention may be applied to essentially any avermectin or milbemycin starting material having hydroxy or protected hydroxy (such as acyloxy) at each of positions C22 and C23. In addition, the compounds of the formulas (A), (B) and (I) to (III) may be modified using techniques which are well known in the art and are described in, for example, Natural Products Reports 3 (2) [1986 ] 87 and seq. and Macrolide Antibiotics [1984] ch14, 553 et seq. Thus, a particular aspect of the invention provides any milbemycin or avermectin of the partial formula (I), as well as a process for the preparation thereof which comprises treating a milbemycin or avermectin of the partial formula (II) with a compound of the formula X-Y-X1.

(i)

Compounds of the formulas (II) and (ii) are novel and constitute a further aspect of the invention. The following example illustrates the present invention. (IA) is the compound of formula (I) wherein R is hydroxy, R is hydrogen, and -Y- is -C (CH) -, and intermediate (IIA) is the compound of formula II) wherein R is hydroxy and R is hydrogen.

Example (a) Synthesis of derivative 230H of VM 48130

Diisobutylaluminum hydride (DIBAL, 1.5M in toluene, 1.2 mL, 1.80 mmol) was added dropwise (over about 10 minutes) to a solution of VM48130 (300 mg, 0.45 mmol) in tetrahydrofuran dried (20 ml) under nitrogen and at -50 ° C. Analysis of the mixture by thin-layer chromatography after 30 minutes showed complete reaction. The reaction mixture was quenched by careful addition of 1M solution of ammonium chloride (5 ml) then allowed to warm to room temperature. 2 M hydrochloric acid (40 ml) was added to a solution extracted with ethyl acetate (3 x 40 ml). The combined organic layers were washed with saturated aqueous sodium hydrogen carbonate (40 mL), dried over magnesium sulfate (anhydrous) and concentrated in vacuo. The crude product was purified by flash chromatography on silica gel (using ethyl acetate as eluant) to afford the 230H derivative of VM 48130 (189 mg, 70%). 13 C NMR (d 6 -acetone: 172.5, 142.4, 141.4, 137.7, 134.4, 134.9, 124.8, 124.4, 121.8, 120.8, 119.3 , 101.0, 81.5, 81.2, 81.0, 78.0, 74.7, 69.0, 68.9, 68.5, 68.2, 49.1, 46.6, 40.2 , 37.5, 36.5, 35.1, 22.7, 19.8, 15.6, 13.6, 13.1 and 11.0 m / z (FAB): 623 (MNa +).

To a solution of the 230H derivative of VM 48130 (200 mg, 0.33 mmol) in methanol (10 ml) at room temperature was added in one portion sodium metaperiodate (150 mg, 0.70 mmol ). Analysis by thin-layer chromatography after 3.5 hours showed a complete reaction. The suspension was cooled to 0øC and sodium borohydride (80 mg, 2.1 mmol) was added. After 10 minutes the mixture was allowed to warm to room temperature and was stirred for another 30 minutes. The mixture was then concentrated in vacuo to about 3 ml. This was then diluted with EtOAc (80 ml), washed successively with 2M hydrochloric acid (40 ml) and saturated aqueous sodium hydrogen carbonate (40 ml), dried over magnesium sulfate (anhydrous) and the solvent was removed in vacuo . The crude product was purified by preparative thin layer chromatography on silica gel using Petrol: Ethyl acetate (1: 2) as eluent to give (HA) (37.5 mg, 24%). 13 C NMR (CDCl 3): 173.4, 142.7, 139.4, 137.7, 137.2, 123.4, 120.5, 120.2, 118.0, 96.9, 80.1, 79.2, 69.0, 68.7, 68.3, 68.2, 67.1, 48.4, 45.6, 36.6, 36.3, 35.9, 34.5, 3, 19.8 and 15.5 m / z (FAB): 499 (MNa +). (c) Synthesis of (IA) To a solution of (IIA) (24 mg, 50.4 μιηοΐ) in dichloromethane (3 ml) at ambient temperature was added 2,2-dimethoxypropane (0.5 ml, 4.07 mmol) and a catalytic amount of p-toluenesulfonic acid. After 4 hours the mixture was diluted with sodium carbonate and saturated aqueous hydrogen (20 ml) and extracted with dichloromethane (2 x 20 ml). The organic layers were dried over magnesium sulfate (anhydrous) and the solvent was removed in vacuo. The crude product (24 mg) was purified by preparative thin-layer chromatography (silica gel) using 1: 2 hexane: ethyl acetate as the eluent. This afforded 9 mg (34%) of (1A). 13 C NMR: 173.61, 142.82, 139.57, 137.96, 137.15, 123.45, 120.73, 120.27, 118.02, 111.54, 104.24, 20, 79.23, 75.12, 69.14, 68.69, 68.50, 67.69, 48.48, 45.72, 38.25, 36.17, 36.00, 34.50, 27.04, 26.69, 22.29, 29.92 and 15.48. m / z (FAB): 539 (MNa +). >

Claims (7)

1. A process for the preparation of a compound of the formula (I): (I) wherein R is optionally protected hydroxy or methoxy, R is hydrogen or 4 '- (Î ± -L-oleandrosyl) -Î ± -L-oleandrosyloxy, and -Y- is an alkylene group optionally substituted by one or more organic radicals; characterized in that it comprises treating a compound of formula (II): (II) Wherein R 1 and R 2 are as defined above, with a compound of formula XYX, wherein X and X are the same or different and each is a leaving group, or, in the case where Y is optionally substituted methylene, X and X 'together with the carbon atom to which they are attached form a carbonyl group, and R 4 is hydrogen or C 1-4 alkyl. 22. A process according to claim 1, 1 . . R 2 is hydroxy and R 2 is hydrogen. 3a. A process according to claim 1 or 2, characterized in that Y is the group -C (CH 3) 2 -. 42. A method of treatment or prophylaxis of endo- and ectoparasitic infestations of animals, especially helminthiasis, comprising administering an effective non-toxic amount of a compound of the formula (I) as defined in Claim 1 or its pharmaceutically acceptable derivative, to a patient in need thereof; the dosage range of active ingredient being from 0.001 to 100 mg per kilogram of body weight per dose, preferably from 0.01 to 10 mg / kg / dose. 4 »ι ι 19 53. A method for eradicating infestations with arthropods or nematodes, comprising applying a compound of the formula (I) as defined in Claim 1 or a derivative thereof to the arthropods or nematodes or their environment, generally in the form of a composition containing from 0.1% to 60% by weight, preferably from 1.0% to 60% by weight, of active ingredient. A process for the preparation of a pesticidal composition, which comprises including in said composition a compound of the formula (I) as defined in Claim 1 or a derivative thereof together with a suitable carrier or excipient. 73. A process for the preparation of a pharmaceutical or veterinary composition which comprises including in said composition a compound of the formula (I) as defined in Claim 1 or a pharmaceutically acceptable derivative thereof together with a pharmaceutically acceptable carrier or excipient or veterinarily acceptable. 83. A process for the preparation of a compound of the formula (II) as defined in Claim 1, wherein a compound of formula (III) is treated: OH milbemycin, with NalO- and MeOH at room temperature, followed by 44. NaBH. at 0 ° C and treatment with HOR in acid medium. 49a. A process for the preparation of a milbemycin or avermectin of the partial formula (I): (i) wherein Y is as defined in Claim 1, characterized in that it comprises the treatment of a compound of formula (ii): ? . X and X are the same or a leaving group, or, in the case in which they are each other, Y is methylenominally substituted, X and X, together with the carbon atom to which they are attached form a carbonyl group, and R4 is hydrogen or C1 -C6 alkyl. 10a. A process for the preparation of a compound of the formula (ii) as defined in Claim 9, characterized in that a compound of the formula: treatment with NaI04 and MeOH at room temperature, followed by NaBH4 at 0 ° C and treatment with HOR4 in acid medium. Lisbon, December 20, 1991 J. PEREIRA DA CRUZ Official Agent of Industrial Property RUA VICTOR CORDON, 10 Ά 3. · 1200 USBOA