GB1573072A - Methyl 5(6) cyclopropylethyl sulphinyl-benzimid azole 2 carbamate particularly active against gastroenteric and lung parasites - Google Patents

Description

(54) METHYL 5(6) CYCLOPROPYLETHYLSULPHINYL- BENZIMIDAZOLE-2-CARBAMATE, PARTICULARLY ACTIVE AGAINST GASTROENTERIC AND LUNG PARASITES (71) We, MONTEDISON S.p.A., an Italian body corporate, of 31 Foro Buonoparte, Milan, Iraly, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to methyl - (5(6) - [(cyclopropylethyl) - sulphinyl]benz- imidazole - 2 - carbamate, to its preparation and its use, in a suitable formulation, for combatting gastroenteric, lung and hepatic parasites of the helminthic type in animals.

Certain 5(6) substituted benzamidazoles and their anti-helminthic action are known. For example German Offenlegungschrifts Nos. 2,029,637 and 2,164,690, French Patent Specifications Nos. 1,556,824 and 2,052,988 and United States Patent Specifications Nos. 3,010,968 and 9,915,986 disclose such compounds and their applications.

Some of these compounds have been sold commercially e.g. Albendazole, Oxybendazole and Parbendazole commercially available from Smith-Kline Co., Phenbendazole commercially available from Hoechst Company, Oxophendazole commercially available from Syntex Co., Cambendazole and Thiabendazole commercially available from MERK Company, and Mebendazole commercially available from. Janssen Co.

All these compounds display a good action against intestinal helminths however, they are, at the most, slightly effective against lung nematoda or hepatic trematoda.

According to the present invention there is provided a new 5(6)-substituted benzimidazolcarbamate, namely, methyl - 5(6) - [(cydopropylethyl) - sulphinyl]- benzimidazole - 2 - carbamate (CPSBC), of the formula:

CPSBC has an anti-helminthic action against specific parasites of cattle, greater than that of the various benzimidazolecarbamates already adopted by veterinarv practice and displays a much wider activity range in as much as it is also effective against lung nematoda and hepatic trematoda that are otherwise difficult to attack with conventional anti-helminthic agents. In fact, besides displaying an exceptional activity against the genera Ostertagia, Oesophagostomum, Trichostronglyns and other intestinai helminths, CPSBC has proved active against Dictyocauli, Metastrongyli, Protostrongyli, lung nematoda, responsible for infections that cannot easily be controlled in sheep, cattle and equines and furthermore it is also effective against Fasciolae such as the Fasciola hepatica CPSBC may be readily prepared from the corresponding thio derivative methyl5(6) - [(cyclopropylethyl) - thio]benzimidazole - 2 carbamate of the formula:

which is oxidised in an inert solvent at OOC. g Suitable oxidizing agents include perbenzoic acid substituted perbenzoic acid, e.g. m-chloroperbenzoic acid, peracetic acid, performic acid and hydrogen peroxide.

The thio derivative may be prepared from 2-nitro-4-thiocyano-aniline and thus the complete reaction scheme may comprise the following steps.

The cyclopropylethylchloride may be prepared from CC and ethylene according to the following reactions:

gaseous HCl Cl ~e Cl-CH2-CH2-CCl2-CH,CH,-Cl CPSBC has proved useful both in freeing infested animals as well as in protecting them from infection. It may be administered according to any one of many known techniques in the veterinary field, for example by mouth, in the form of bolus, tablet, capsule or suspension or may be directly admixed to the fodder.

CPSBC is compatible with many of the usual diluents or excipients e.g. maize starch, lactose, saccharose, calcium phosphate, jelly, stearic acid, agar and pectin.

Suitable liquid vehicles include peanut oil and olive oil, which thus allows CPSBC to be used in conventional formulations.

Animals may be treated for gastroenteric helminths, lung nematoda and hepatic trematoda by administering at least one dose of CPSBC at a dosage rate of at least 2.5 mg/kg.

The activity of the compound according to this invention has been determined in comparison with those of the prior art, in experiments on sheep which were thoroughly treated by administering suitable doses of conventional anti-helminthic products and subsequently infested in a controlled way with parasites of the species under examination. The infested animals were then subdivided into two groups, one of which was treated with one single oral dose of the product under examination in the form of an aqueous suspension, while the other group was used as a control. 48 hours after administering the anti-helminth, the animals were sacrificed and the parasites present in them were counted according to conventional techniques in helminthologic practice.

The results, presented in Table 1, have been expressed as percentage of disinfestation, according to the following classification:

Classification % of disinfestation 0 0-10, or irrelevant 1 11-25 2 26-60 3 61-90 4 91-100 Table I

cd d cd cd 0 R in the structure Nematoda Cestoids Trematoda N Gastroentheric of the lung k Dose mg/kg Ostertagia Moniezia Fasciola E Dyctocaulus Ers: C) > t1 n I O l l d1 1 - accordance with the 2 t cd cd aS qO 2.5 1 1 - o m O 5 (b) O bD CdC dm0 h CMOk p 4 0 0 0 2.5 2 2 - M E 5 e 4 4 1 2.5 4 1D 4 1D U: N L0 N ç me O N / 3 < N Table I Contd.

cd So in the structure CU O E c, v FrC m OeSo0fOtOgyU15 Dyctocaulus cud p rl CO- 5 | | o 2.5 . - ç S cd 9) 0 90 0t O b &verbar; X - - ~ d O X X S d9n Q pH X O O5 s: bD O h n &commat; d 9 n I O t X h h 4 0 v ~v Ul 4 al u} O h V O O Es O ID CQ U) e U) O n o Jw m z X t] (1) according to British Patent Specification No. 1 455 728 (a) at 1mg/kg there is still complete efficacy.

(b) requires does of 12.5 mg/kg in order to be effective.

(c) requires 5 does of 10 mg/kg each.

(d) requires does of more than 25 mg/kg.

(e) requires does of 20 mg/kg.

(f) requires does of 60 mg/kg.

The results obtained show the very high efficiency of the CPSBC against all the helminths examined in particular with regard to lung nematoda and to trematoda.

CPSBC is clearly superior to oxiphendazol which is the only prior art compound having comparable properties.

The results indicate that CPSBC taken in one single dose of 5 mg/kg, allows the full and simultaneous disinfestation in sheep from nematoda, cestoids and trematoda, which has been impossible to achieve with any of the known products used alone.

A preparation of the compound of the invention will now be illustrated by the following Example.

Example.

(a) Preparation of

2.1 kg (11.5 moles) of CCl,-CH2-CH2-Cl, 1 1 of CH3CN, 20 g of FeCl2 . 4H2O, 22 g of (C,H,)2--NH.HC1 and 21 g of benzoin were introduced into an enamelled, 5-litre autoclave, provided with a suitable stirring system and heating apparatus. The air was removed and the autoclave was pressurised with several atmospheres of ethylene. The temperature was then raised to 1200C and further ethylene introduced until a pressure of 35 atm. was reached. The conditions were maintained for 5+ hrs. introducing further ethylene according to its consumption during the reaction. After filtering the suspended solids, the resulting mixture was fractioned by distillation to yield 1300 grams of a fraction boiling at 80 to 820C at 2mmHg. The fraction consisted of 97% of

Under the above conditions the conversion of the CCl,CH2CH2Cl amounted to 65% while the selectivity towards the desired product was 80%, corresponding to a yield of 52%.

(b) Preparation ot

210 g of

(1 mole), 1000 cc of ethanol and 325 g (5 moles) of Zn powder were introduced into a flask fitted with a reflux condenser, a stirrer and a thermometer. The reaction mixture was reflux heated (temperature of the outside heating bath=97 to 98"C) and then gaseous HCl was bubbled through the reactor, maintaining a slight but constant flow. The reaction course was followed using chromatographic analysis and was terminated when the

appeared to be completed consumed. The reaction mixture was then diluted with 300 cc of aqueous HCI at 5% concentration to increase its fluidity, and was then extracted with diethyl ether removing the aqueous phase. The organic phase, after dehydration, was concentrated and the residue was fractioned at atmospheric pressure gathering a fraction boiling at 109 to 111"C. 86 g of

were obtained which from chromatographic analysis proved to be 98% pure. This corresponds to a molar yield of 80% on the

(c) Preparation of 4 - [cyclopropylethyl - thio] - 2 - nitro - aniline 51.2 millimoles of 2-nitro-4-thiocyano-aniline dissolved in 25 cc of dimethylformamide (DMF) and 54 millimols of sodium borohydride dissolved in 25 cc of DMF were mixed together at room temperature under moderate stirring. Thereupon the temperature rose in an autogenous way to 30 to 350C.

The mixture was maintained under stirring for 1 (one) hour at room temperature (15 to 20 C) after which 66 millimols of

were introduced regulating the feeding in such a way as to maintain the temperature below 250C. On completion of the addition, the mixture was heated for 3 hours at 100"C. The reaction mass was then cooled and poured into water under vigorous stirring. Extraction with chloroform was then carried out, the organic extracts being gathered together, dried on Na2SO4 and the solvent removed under vacuum. The yield of raw product thus obtained amounted to 85%. The product was suitable to be used directly for the succeeding synthesis.

(d) Preparation of 4 - [cyclopropylethyl - thio - ] - orthophenylenediamine.

34.4 millimoles of 4- [cyclopropylethylthio] -2-nitro-aniline were suspended in 340 cc of the mixture 1:1 by volume of methanol and water containing 43 g of Na2S204.

The mixture was then reflux heated, and the course of the reaction followed by thin-layer chromatography. The reaction was completed in 10 to 15 minutes. On completion the methanol and part of the water were removed under vacuum to yield an oily suspension which was extracted with chloroform.

The organic extracts were dried on anhydrous Na2SO.l and the solvent evaporated under vacuum to obtain raw diamine (a thick, intensely coloured oil) with a practically quantitative yield. The product was suitable to be used directly for the succeeding step.

(e) Preparation of methyl 5(6) - [(cyclopropylethyl) - thio - ] benximidazole - 2 carbamate.

16 millimoles of 4 - [(cyclopropylethyl) - thio - ] - o - phenylenediamine and 18 millimoles of 1,3-methoxycarbonylisothiourea were dispersed in 20 cc of a mixture of C2H,OH/H2O/CHaCOOH (40:40:1). The mixture was refluxed for 4 hours and the solid that formed in the reaction medium was filtered and re-crystallized from methanol and chloroform (1:1) to yield the desired benzimidazole carbamate.

Yield=70%; melting point: 187 to 189"C.

(f) Preparation of methyl 5(6)[(cyclopropylethyl)sulphinyl] benzimidazole-2 carbamate.

2.39 millimoles of the ester obtained in step (e) were dissolved in a mixture of CHCl, (400 cc), methanol (100 cc) and acetic acid (2 cc). The temperature was maintained at 0 C and 2.51 millimoles of m-chloroperbenzoic acid were added. After 1 hour the reaction was complete, as established by thin layer chromatography (Silica gel-Eluting solution: mixture of CHCl, 3 parts, CH3COOC2H; 2 parts, CH,OH 1 part).

The organic solution was washed with 150 ml of a saturated aqueous solution of Na HCO3, the organic phase dried on Na2SOs and evaporated to dryness under vacuum. The oily residue thus obtained was dissolved in methanol and crystallized to yield the sulphoxide. Recrystallizing from methanol the pure sulphoxide was obtained having a melting point of 215 C; yield 85%.

Claims (10)

1. WHAT WE CLAIM IS: 1. Methyl - 5(6) - (cyclopropylethyl) - sulphinyl]benzimidazole - 2 - carbamate of the formula:
2. 2. A process for preparing the compound claimed in Claim 1 in which methyl5(6) - [(cyclopropylethyl) - thio]benzimidazole - 2 - carbamate of the formula:

   is oxidised in an inert solvent at OOC.
3. 3. A process as claimed in Claim 2 in which the oxidising agent is perbenzoic acid or substituted perbenzoic acid, peracetic acid, performic acid or hydrogen peroxide.
4. 4. A process as claimed in Claim 3 in which the oxidising agent is m-chloroperbenzoic acid.
5. 5. A method as claimed in any one of claims 2 to 4 in which the methyl-5(6) [ (cyclopropylethyl)-thio]benzimidazole-2-carbamate is prepared according to the reaction scheme
6. 6. A process for the preparation of methyl 5(6)-[(cyclopropylethyl)-sulphinyl] benzimidazole - 2 - carbamate substantially as herein described with reference to the Example.
7. 7. Methyl 5(6) - [(cyclopropylethyl) - sulphinyl] benzimidazole - 2 - carbamate when prepared by a process as claimed in any of claims 2 to 6.
8. 8. A composition suitable for fighting infestations from gastroenteric helminths, lung nematoda, and hepatic trematoda, comprising a physiologically acceptable carrier and, containing as an active ingredient, a compound as claimed in claim 1 or claim 7.
9. 9. A method of combating gastroenteric helminths, lung nematoda and hepatic trematoda in animals other than humans, which comprises administering to the animal at least one dose at a dosage rate of 2.5 mg/kg of a compound as claimed in claim 1 or claim 7.
10. 10. A method as claimed in claim 9 in which the compound is administered in the form of a composition as claimed in claim 8.