IE43318B1 - 2-(amino or acylamino)-1-(2-thiazolin-2-yl)-benzimidazoles - Google Patents

Abstract

A process for the preparation of Thiazolinylbenzimidazoles, wherein Eian is used, for example, to prepare Tf (thiazolixv-2-ω) -2-amino-5 (6) -benzoylbenzimidazole 2-amino-5 (-6) benzoylbenzimidazole with sodium hydride and

Description

The incidence of viral upper respiratory disease is immense. It has been estimated that nearly a billion cases annually appear in the United States alone. Studies performed in England (Tyrell and Bynoe, 1966) indicated that 74 percent of persons having colds were infected with rhinoviruses. Because more than 80 strains of rhinoviruses are already identified, the development of a practical rhinovirus vaccine is not feasible. In this, chemotherapy appears to be the more desirable approach.

The ability of chemical compounds to suppress the growth of viruses in vitro is readily demostrated by using a virus plaque suppression test similar to that described by Siminoff, Applied Microbiology, 9(1), 66(1961).

Certain thiazolinyl benzimidazole compounds are disclosed in the following references: U. S. Patent Specification 3,749,717 discloses 1-thiazolinyl 2-(heterocyclic)benzimidazoles useful as anthelmintic and anti-inflammatory agents.

U. S. Patent Specification 3,825,537 discloses 1-thiazolinyl 2-aminobenzimidazoles useful as anthelmintic and antiinflammatory agents.

U. S. Patent Specification 3,833,574 discloses a method of preparing l-thiazolinylbenzimidazolin-2-ones which are anti-inflammatory agents.

Derwent 26199W/16 discloses 1-thiazolinyl-2phenylbenzimidazoles useful as anthelmintic agents.

There is no known prior art reference to antiviral activity of thiazolinyl benzimidazoles. -243318 It is an object of this invention to provide novel thiazollnyl benzimidazole compounds which are useful for suppressing the growth of viruses, particularly rhinoviruses, polio viruses, Coxackie viruses, echo virus, Mengo virus, and influenza.

This invention concerns the pharmacologically useful benzimidazole compounds of the general formula wherein R Is hydrogen, or C1~C4 acyl; R^ is hydrogen, C^-Cg alkyl, C3~Cg cyeloalkyl (as herein defined), (C^-Οθ cycloaklyl)methyl, l-(C3~Cg cyeloalkyl)ethyl, thienyl or phenyl and m is 1 or R^ is 1-(0^-0^ alkyl)-tetrazol-5-yl or l,3-dithiolan-2-yl, and m is 0 Z is oxygen, hydroxy imino, C-^-C^ alkoxyimino, C^-C^acyloxyimino, a —methoxycarbonylraethozyimino, a —hydroxycarbonylmethoxyimino, or thiocarbamoylhydrazono; Π R^—ICA-is at the 5 or 6 position; and n is 0, 1 or 2; subject to the limitations that is other than C^-Cj alkyl or phenyl when R is hydrogen and Z is oxygen.

The compounds of formula (I)canbeprepared hy reacting a compound of the general formula wherein R^ is hydrogen, alkyl, C^-Cg cycloaikyl (as herein defined), (C^-Cg cycloaikyl)methyl, l-JC^-Cg cycloaikyl)ethyl, thienyl or phenyl and m is 1 or R^ is 1-(0^-0^ alkyl)-tetrazol-5-yl or l,3-dithiolan-2-yl and m is 0 and Z' is oxygen with a base and a haloethylisothiocyanate of the formula X-(CH2)2-NCS (IV) optionally mono- or di-substituted on the C chain with methyl groups, wherein X is chloro or bromo, optionally followed, where necessary, by reaction of a compound obtained with a substituted amine to obtain the compounds of formula (I) wherein Z is other than oxygen, C^-C^ acyloxyimino or C^-C^ alkoxyimino, optionally followed by alkylation of the compounds of formula (I) where Z is hydroxyimino to provide the compounds of formula (X) where Z is alkoxyimino, and/or followed by acylation to obtain the compounds of formula (X) wherein R is C^-C^ acyl and/or when Z is hydroxyimino to obtain compounds of formula (I) wherein Z is C^-C^ acyloxyimino.

The present invention relates to thiazolinyl benzimidazole compounds useful in suppressing the growth in mammals of certain viruses including rhinovirus, polio, Coxsackie, echo virus, Mengo virus and influenza. The compounds of this invention are prepared by reacting the salt (XII) of a tautomeric ben4 zimidazole compound represented by the formula (II) with an haloethylisothiocyanate of the formula (IV), X—(O^Jj-NCS, which can be optionally substituted on the carbon chain with up to two nethyl groups wherein R^, 2', m, and n are as defined hereinabove and X is chloro or bromo, to yield a compound of formula (V) (formula (I) above wherein R is hydrogen, and Z is oxygen or m = 0 and Rj^ is l,3-dithiolan-2-yl). (anion) X(CH ) NCS ϋ 2 -543318 The term tautomeric benzimidazole refers to a benzimidazole reagent of formula (II) which can be substituted at either nitrogen atom with a hydrogen atom. The benzimidazole reactant, unsubstituted on nitrogen and bearing an —ycj— substituent group at the 5-position of the benzene moiety has a corresponding tautomeric form with which it is in equilibrium wherein the substituent resides alternatively at the 6-position. The isomer mixture can be indicated by numbering the alternate positions as 5(6). As a consequence of such tautomerism, the reaction of a 5(6)substituted benzimidazole salt (III) with the haloethylisothiocyanate (IV) produces isomeric mixtures of 5- or 6-substituted thiazolinyl benzimidazoles (V), named herein as 5(6)-substituted compounds.

The following definitions refer to the various terms used throughout this disclosure. The term C^-C^ alkyl refers to methyl, ethyl, propyl and isopropyl. The term C^-C^ alkyl includes within its definition the term C^-C2 alkyl.

The term C^-Cg eycloalkyl refers to the saturated alicyclic rings of throe to six carbon atoms, optionally substituted with a methyl group, such as cyclopropyl, methylcyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The term (C^-Cg eycloalkyl)methyl refers to a methyl radical substituted with saturated alicyclic rings of three to six carbon atoms as exemplified above in the term C^-Cg eycloalkyl. The term l-fC^-Cg cyclo-643318 alkyl)ethyl refers to ethyl radicals substituted on the carbon atom in the 1 position with saturated alicyclic rings of three to six carbon atoms as described above.

The term C^-C^ alkoxyimino refers to the 5 O-aliphatic hydroxylimino radical derived from hydroxylamine and an alkyl group of one to four carbon atoms. Methoxyamine hydrochloride is available from commercial sources.

Other hydroxylamine derivatives are available by (A) alkylation of acetone oxime by C-L-C4 alkyl halides followed by acid hydrolysis, (B) alkylation of N-hydroxyphthalimide followed by hydrazinolysis or (C) alkylation of benzohydroxamic acid followed by acid hydrolysis. The term C^-C4 acyloxyimino refers to formyloxyimino, acetoxyimino, propionyloxyimino, butyryloxyimino, and isobutyryloxyimino.

The term C^-C4 acyl refers to the acyl radical of one to four carbon atoms such as formyl, acetyl, propionyl, and butyryl.

The term thiazolinyl or thiazolin-2-yl refers to the Νχ substituent moiety of formula I and indicates a 4,5-dihydro20 thiazole radical attached at the 2-position which may have substituent methyl groups on the 4- and/or 5-positions.

It Illustrative of the carbonyl functions, R^-C-, which are included in the scope of formula (I) are formyl, cyclopropylcarbonyl, cyclobutylcarbonyl, cyclopentylcar-743318 bonyl, cyclohexylcarbonyl, cyclopropylacetyl, cyclobutylacetyl, cyclopentylacetyl, cyclohexylacetyl, 2-cyclopropylpropionyl, 2-cyclobutylpropionyl, 2-cyclopentylpropionyl, or benzoyl.

The ccstpounds of formula (V) (formula (I), wherein R is hydrogen, m is 1 and Z is oxygen or m is 0 and is l,3-dithiolan-2-yl), can be prepared by first converting the appropriately substituted benzimidazole reactant (XI) into its salt (III) by employing a base such as metal hydrides; e.g., sodium hydride or potassium hydride; a metal amide; e.g., sodium amide; or alkali metal alkoxides; e.g., sodium methoxide, potassium ethoxide or sodium butoxide . Anion formation can be brought about in a variety of aprotic solvents such as aromatic hydrocarbons; e.g., benzehe, toluene or xylene, or ethers such as ethyl ether, monoglyme or tetfahydrofuran., at a temperature ranging from 0° C. to 150° C, for periods of one hour to twenty-four hours. A slight excess of the base is desirable; thus the molar ratio of the benzimidazole reactant to base can range from 1:1 to 1:2.

The benzimidazole anion (III) is reacted with an aliphatic haloethylisothiocyanate (IV) to yield a thiourea intermediate in situ which undergoes intramolecular alkylation on the sulfur atom to form a 1-thiazolinylbenzimidazole product represented by formula (V). The molar ratio of the benzimidazole reactant (II) to haloethylisothiocyanate (IV) can range from 1:1 to 1:1.5 and the reaction time can vary from one to twenty-four hours at temperatures -843318 I row 25° C. to 150° C. The methods and conditions for preparing the 1-thiazolinylbenzimidazole products are analogous to those disclosed in U. S. patent specifications No. 3,749,717 and 3,825,537.

The thiazolinyl benzimidazole products are isolated by conventional methods such as filtration and concentration of the filtrate to induce crystallization. Alternatively the reaction mixture can be evaporated to dryness and the residue treated with a suitable solvent such as acetone or methanol to separate and remove any insoluble material. The solution containing the product is concentrated to crystallize the product or is evaporated to give a second residue, which residue is recrystallized from methanol for example. The benzimidazole compound is re15 covered by filtration or centrifugation.

The reaction of the tautomeric anion (III) with the haloethylisothiocyanate generally provides a 1:1 mixture of 5(6)-isomers of thiazolinyl benzimidazole product. The 5(6)-isomers are separable by fractional crystallization or 2o by column chromatography. Usually the 6-isomer crystallizes first from a solution of the mixture. Individual isomers except for the 5(6/ benzoyl compounds or their derivatives can be unambiguously characterized by their proton magnetic resonance spectra in the phenyl proton region (7.0 to 8.3 ppm).

The thiazolinyl benzimidazole compounds, wherein R is C-^-C^ acyl and Z is oxygen, can be prepared by reacting the l-thiazolinyl-2-amino-5(6)-substituted-benzimidazoles prepared as above with the anhydrides of acetic, propionic -943318 or butyric acid or the mixed anhydride of formic acid and acetic, propionic or butyric acid; or when R is formyl by reaction with the mixed anhydride of formic acid and acetic acid.

The nitrogen derivative of the keto benzimidazole compounds are represented by formula (I) wherein Z is a nitrogen function bonded to the carbon atom of the original carbonyl group. These compounds are prepared by reacting the appropriate l-thiazolinyl-2-substituted-5(6)-ketobenzimidazole with e.g. hydroxylamine, C^-C^ alkoxyamines, carboxymethoxylamine or thiosemicarbazide or their salts in the conventional manner. When the carbonyl (keto) function reacts sluggishly with the carbonyl reagent it can be activated by protonating the keto compound under acidic conditions. Upon protonation subsequent carbon-nitrogen double bond formation occurs readily.

Z Jl The nitrogen function Z in R^-C- is named according to the carbonyl reagent from which it is derived as follows: carbonyl reagent hydroxylamine methoxyamine ethoxyamine propoxyamine butoxyamine thiosemicarbazide carboxymethoxy1amine Z (function) =N-OH =n-och3 =N-OC..Hr 2 5 =N-OC3«7 =N-OC4Hg =NNHC(S)NH2 =NOCH2CO2H Z (name) hydroxy imino methoxyimino ethoxyimino propoxyimino butoxyimino thiO'carbamoy lhydra zono hydroxycarbonylmethoxyimino -1043318 The compounds wherein Z is C^-C4 acyloxyimino can be prepared by reacting a compound of formula (1) wherein Z is hydroxyimino (=N-OH) with the anhydrides of acetic, propionic or butyric acids. When the compound bearing the hydroxyimino function is reacted with the mixed anhydride of formic acid and acetic acid, the product is the formyloxyimino derivative wherein Z is =N-O-CHO. A hydroxyimino compound of the formula (I) wherein R is hydrogen can be reacted with one equivalent of a Cj-C4 acid anhydride to affect O-acylation selectively to provide the products wherein R is hydrogen and Z is C^-C4 acyloxyimino. A hydroxyimino compound of formula (I) wherein R is hydrogen can also be reacted with a molar excess of a C^-C4 acid anhydride to provide the diacylated products wherein R is Cl-C4 acyl an^ 2 is C1_C4 acyloxyimino an^ both acyl functions are the same. A hydroxyimino compound of formula (I) wherein R is acyl can be reacted with one equivalent of the same or a different acid anhydride to provide the products wherein R is Cj-C^ acyl and Z is C^-C4 acyloxyimino and the acyl functions may be the same or different. For example, when 1-(thiazolin-2-yl)-2-amino5(6)-(α-hydroxyiminobenzyl)benzimidazole is reacted with one equivalent of acetic anhydride, the mono acylated product, 1-(thiazolin-2-yl)-2-amino-5(6)-(a-acetoxyiminobenzyl)benzimidazole, is obtained. When the same compound is reacted with at least two equivalents of acetic anhydride the diacylated product, 1-(thiazolin-2-yl)-2-acetamido-5(6)(α-acetoxyiminobenzyl)benzimidazole, is obtained.

The most preferred compounds are those nitrogen derivatives wherein Z is hydroxyimino or C3-C4 acyloxyimino. -113313 The 6-isomers of such compounds are preferred over the 5isomers.

It will be appreciated by those skilled in the art that the intermediate compounds can be obtained by any suitable synthesis. For example the benzimidazole reactant can first be chemically modified to provide desired substituents and then reacted with the appropriate haloethylisothiocyanate to provide the thiazolinyl benzimidazole product. Alternatively a 1-thiazolinylbenzimidazole compound can be prepared initially and then be modified chemically to provide the final desired product. Since the insertion of the thiazolinyl moiety into the benzimidazole reactant requires reaction with base, those benzimidazole reactants are preferred which have substituent groups which are not susceptible to attack by base. For example, in those compounds wherein R is C^-C^ acyl or Z is a nitrogen function, which compounds have some instability in base, it is preferred that the acyl or nitrogen function be introduced after the thiazoline moiety has been formed.

The required keto benzimidazole reactants in which is other than hydrogen can be prepared from the appropriate keto o-phenylenediamine compounds by methods known to the benzimidazole art. For example, Belgian published application No. 93791 discloses the preparation of keto o-phenylenediamines of the formula II -1243318 wherein is cy“c3 alkyl, C3-Cg cyeloalkyl or phenyl. The method of preparation involves the ammonolysis and reduction of a 4-halo-3-nitrophenyl ketone, prepared by the FriedelCrafts reaction of either (1) a 4-halo-3-nitrobenzoyl chloride with an appropriate hydrocarbon or (2) a halobenzene with an appropriate acid chloride followed by aromatic nitration. Such methods make available the required keto o-phenylenediamines wherein R^ in the formula above is additionally (C^-C? cyeloalkyl)methyl, l-CC^-C? cyeloalkyl) ethyl or thienyl. Alternatively the keto benzimidazole reactants can be prepared from acetanilide by a FriedelCrafts acylation with the appropriate derivative of a alkanoic acid, a C^-Cg cyeloalkyl carboxylic acid, a C^-Cg cycloalkylacetic acid, a 2-(C3~Cg cyeloalkyl)propionic acid, or benzoic acid. The resulting 4-keto acetanilide is nitrated to give a 2-nitro-4-ketoacetanilide and the acetanilide is hydrolyzed to provide a 2-nitro-4ketoaniline. The nitroaniline is hydrogenated catalytically to yield a 4-keto-c2,-phenylenediamine which is reacted with cyanogen bromide to provide the appropriate 2-amino-5(6)ketobenzimidazole.

The required keto benzimidazole reactants in which Rj is hydrogen can be prepared from 4-chloro-3-nitrobenzyl alcohol. The benzyl alcohol is ammoniated to give 4-amino3-nitrobenzyl alcohol which is hydrogenated catalytically to yield 4-hydroxymethyl-o-phenylenediamine. The phenylenediamine is reacted with cyanogen bromide by the methods known to the benzimidazole art to provide 2-amino-5(6)hydroxyethylbenzimidazole. The hydroxymethyl group of the -133318 benzimidazole compound can be oxidized with Jones reagent (a solution of chromic acid and sulfuric acid in water) to provide the corresponding 5(6)-formyl benzimidazole.

Other required benzimidazole reactants can be prepared by cyclizing o-phenylenediamines substituted with 1-(C^-C3 alkyl)-tetrazol-5-yl. The 2-aminobenzimidazole compounds can be prepared by cyclizing the appropriate o-phenylenediamines with cyanogen bromide as described by Buttle et al., Biol. Chem. J. 32, 1101 (1938) and British Patent Specification No. 551,524. The preparation of a variety of benzimida zoles is well documented in Weissberger1s The Chemistry of Heterocyclic Compounds, Imidazole and Its Derivatives (Interscience Publisher Co., New York, 1953).

The required haloethylisothiocyanate reactants, formula (IV) above, optionally substituted with methyl groups, are readily prepared from their corresponding haloalkyl amines (VI) and thiophosgene: CSCl.

X-(CH2)2-NH2 -=->SCN-(CH2) 2-X base Additional routes for the preparation of haloethylisothiocyanates (IV) are described in Houben-Weyl's Methoden Der Organischen Chemie, Vol. 9 (G. Thieme Verlay Stuttgart, 1955). Examples of haloethylisothiocyanates which can be employed herein include the following: SCN(CH2)2Br, SCN(CH2)2C1, SCNCH (CH-j) CH (CH3) Cl, SCNCH(CH3)CH2C1, and SCNCH2CH(CHf)Cl. -144 33 tS Preferred compounds of this invention are the 1-(thiazolin-2-yl)-2-amino-5(6)-keto0 benzimidazoles wherein in the carbonyl function, R^-C-, R^is other than C^-C^ alkyl or phenyl.

Illustrative of the preferred thiazolinyl ketobenzimidazole compounds included in the scope of formula (I) are the following: 1-(thiazolin-2-yl)-2-propionamido-5(6)-formylbenzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-formylbenzimidazole, 1-(thiazolin-2-yl)-2~acetamido-5(6)-(2-cyclopropylpropionyl)benzimidazole, 1-(5-methylthiazolin-2-yl)-2-amino-5(6)-cyclobutylcarbonylbenzimidazole, 1-(4-methylthiazolin-2-yl)-2-amino-5(6)-(2cyclopentylacetyl)benzimidazole, 1-(thiazolin-2-yl)-2-acetamido-5(6)-formylbenzimidazole, 1-(thiazolin-2-yl)-2-acetamido-5(6)-cyclohexylcarbonylbenzimidazole, 1-(5-methylthiazolin-2-yl)-2-amino-5(6)-(2cyclopentylacetyl)benzimidazole, 1-(5-methylthiazolin-2-yl)-2-acetamido-5(6)-(1methoxyiminopropyl)benzimidazole, 1-(thiazolin-2-yl)-2-propionamido-5(6)-(1thiocarhamoylhydrazonoethyl) benzimidazole, -1543318 1-(thiazolin-2-yl)-2-propionamido-5(6)-(αmethoxyiminocyclobutylmethyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(a-propoxyiminocyclohexylmethyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(a-thiocarbamoylhydrazonocyclopentylmethyl) benzimidazole, 1-(thiazolin-2-yl)-2-propionamido-5(6)-(1methoxyimino-2-cyclobutylethyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(1-thiocarbawoylhydrazono-2-cyclopentylethyl)benzimidazole, 1-(thiazolin-2-yl)-2-amino-5(6)-(a-hydroxyiminobenzyl) benzimidazole, 1-(thiazolin-2-yl)-2-amino-5(6)-(α-butoxyiminobenzyl) benzimidazole, 1-(thiazolin-2-yl)-2-amino-5(6)-(α-acetoxyiminobenzyl) benzimidazole, 1-(5-methylthiazolin-2-yl)-2-acetamido-5(6)-(1formyloxyiminopropyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(1-acetoxyiminobutyl)benzimidazole, 1-(thiazolin-2-yl)-2-propionamido-5(6)-(aacetoxyiminocyclobutyImethyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(a-butyryloxyiminocyclohexylmethyl)benzimidazole, 1-(thiazolin-2-yl)-2-propionamido-5(6)-(aacetoxyiminocyclopropylmethyl)benzimidazole, 1-(thiazolin-2-yl)-2-formamido-5(6)-(a-propionyl oxyiminocyclohexylmethyl) benz imida zole, -164 3 31s The following examples illustrate further the preparation of starting materials, intermediates, and compounds of formula (I) .

Example 1 1-(thiazolin-2-yl)-2-amino-5(6)-substitutedbenzimidazoles (general procedure) Five millimoles, 140 mg., of sodium hydride as a 50 percent suspension in mineral oil is washed with n-pentane about three times by decanting off the washings. The washed sodium hydride is suspended in 5 ml. of dimethylformamide under anhydrous conditions. Five millimoles of the appropriate 2-amino-5(6)-substituted-benzimidazole dissolved in 25 ml. of dimethoxyethane (monoglyme) or a mixture of monoglyme and dimethylformamide (DMF) (15:1 ratio) is added dropwise with stirring to the base suspension. Stirring is continued for several hours at room temperature to allow substantially complete anion formation. Five millimoles, 605 mg., of chloroethylisothiocyanate in dimethylformamide is added dropwise to the anion solution and stirring is continued overnight. The reaction mixture is evaporated to dryness in vacuo. The residue is taken up in ethyl acetate and filtered. The ethyl acetate filtrate is washed with water and dried. The 1-(thiazolin-2-yl)-2-amino-5(6)substituted-benzimidazole product is recovered by evapora25 tion or concentration of the solvent. The product is purified by recrystallization from suitable solvents such as ethyl acetate, chloroform, methanol or mixtures thereof.

The following compound was prepared by the methods described above from the appropriate 2-aminobenzimidazole -1743318 substituted, in the 5(6)-position with the appropriate benzoyl group. 1-(Thiazolin-2-yl)-2-amino-5(6)-benzoylbenzimidazole. The yield was 680 mg. (8.j percent) from 6.4 g. (27 mmole) of 2-amino-5(6)-benzoylbenzimidazole.

Analysis C17H15N4OS MW 323 Calcd: C, 63.34; H, 4.38; N, 17.38; S, 9.93.

Found: C, 63.14; H, 4.19; N, 17.08; Ξ, 9.72. Example 2 Three-hundred grams (1.52 mole) of 4-amino-benzophenone were added in portions to a stirred solution of 250 ml. of acetic anhydride in 250 ml. of benzene. The temperature of the mixture rose to about 70°C. The reaction mixture was stirred overnight. The precipitated product was filtered, washed with benzene and dried. The yield of 4-acetamidobenzophenone was 333.8 g. (91.5 percent yield), mp. 150-152°C. (Lit. mp. 155°C, Chem Abst. 55, 18651).

Twenty-three grams (0.1 m.) of 4-acetamidobenzophenone, 50 ml. of acetic anhydride and 20 ml. of acetic acid were stirred together. A solution of 90 percent nitric acid (15 ml.), 10 ml. of acetic acid and 0.2 g. of urea was added dropwise to the benzophenone mixture. The reaction mixture was maintained at a temperature of about 50°C. during the nitration. The mixture was stirred at ambient temperature whereupon the mixture became very thick. The thick slurry was poured over ice and the insoluble product was filtered to yield 17.7 g. (62.5 percent yield) of 4-acetamido-3-nitroben zophenone. -1843318 Analysis C15H12N2°4 MW 284.27 Calcd: C, 63.38; H, 4.26; N, 9.85; 0, 22.51.

Found: C, 63.57; H, 4.03; N, 9.90; 0, 22.27.

Ten grams of 4-acetamido-3-nitrobenzophenone was added portion-wise to 40 ml. of sulfuric acid. The reaction temperature was moderated with a water bath. After stirring about 45 minutes the reaction mixture was carefully poured over ice. The precipitated product was filtered to yield 4-amino-3-nitrobenzophenone.

Analysis ci3hi0n2°3MW 243.23 Calcd: C, 64.16; H, 4.16; N, 11.56; 0, 19.81.

Found: C, 64.19; H, 4.00; N, 11.37; 0, 19.72.

Fifty grams of 4-amino-3-nitrobenzophenone was hydrogenated at room temperature in 945 ml. of tetrahydro15 furan with 15 g. of Raney nickel at 2.74 x 106 dynes/cm2.

After 4 hours three equivalents of hydrogen were absorbed.

The catalyst was filtered and the filtrate was evaporated in vacuo to a solid residue. The residue was chromatographed over silica gel using ethyl acetate as eluant. Fractions -9 were combined to yield 43.6 g. (100 percent yield) of 3,4-diaminobenzophenone.

Two-tenths mole, 42.4 g., of 3,4-diaminobenzophenone were dissolved in 100 ml. of methanol and mixed into one liter of water. Two-tenths mole, 21.8 g, of cyanogen bromide were added in portions to the reaction mixture with stirring. The reaction was continued overnight. The reaction mixture was filtered and the filtrate was neutralized (pH=7.00) with concentrated ammonium hydroxide. The precipitated product was collected, washed with water, and -193318 dried in a vacuum oven to yield 31 g. (68.5 percent) of 2-amino-5(6)-benzoylbenzimidazole.

Analysis C14H11N3O MW 237.2 Calcd: C, 70.87; H, 4.67; N, 17.71.

Found: C, 70.88; H, 4.60; N, 17.48.

The 2-amino-5(6)-benzoylbenzimidazole was then reacted by the procedure of Example 1 to yield 1-(thiazolin-2-yl)-2-amino-5(6)-benzoylbenzimidazole, identical to the product of Example 1.

Example 3 Five millimoles, 1.61 g., of 1-(thiazolin-2-yl)2-amino-5(6)-benzoylbenzimidazole, 1.0 g. of hydroxylamine hydrochloride, and 200 ml. of methanol were heated at reflux for about 12 hours. The reaction mixture was concentrated to about one-half the original volume by evaporation on a steam bath. The mixture was diluted with one hundred milliliters of buffer solution (pH=7.00). The precipitated product was collected to yield 650 mg. (40 percent) of 1-(thiazolin-2-yl)-2-amino-5(6)-(α-hydroxyiminobenzyl)benzimidazole.

Analysis ci6Hi5N5OS MW 325 Calcd: C, 60.52; H, 4.48; N, 20.76.

Found: C, 60.13; H, 4.40; N, 20.37.

Example 4 One and three tenths grams of 1-(thiazolin-2yl)-2-amino-5(6)-benzoylbenzimidazole were dissolved in 160 ml. of methanol and 4 ml. of IN hydrochloric acid.

Eight hundred milligrams of thiosemicarbazide were added and the mixture was heated at reflux with stirring overnight. -2043318 The reaction was concentrated to one half the original volume in vacuo. Eighty milliliters of buffer solution (pH=7.00) were added to the mixture. Upon standing the product precipitated. The product was collected to yield 1.3 g. of 1-(thiazolin-2-yl)-2-amino-5(6)-(a-thlocarbawylhydrazonobenzy1) benzimidazole.

Example 5 (A) 4-Amino-3-nitrobenzyl alcohol Fifty grams (0.27 mole) of 4-chloro-3-nitrobenzyl alcohol, 250 ml. of methanol and 200 ml. of liquid ammonia were loaded into a cold autoclave. The autoclave was sealed and heated to a temperature of 150°C. After cooling, the autoclave was vented and the volatile constituents removed by evaporation in vacuo. The residue was taken up in ether and the ether solution was filtered to remove ammonium chloride which had precipitated. The ether filtrate was evaporated in vacuo to yield a solid product. The product was recrystallized from absolute ethanol/ethyl acetate to give 23.6 g. (52 percent yield) of 4-amino-3-nitrobenzyl alcohol, mp. 100-101°C.

Analysis: C?H8N2O3 MW 168 Calcd: C, 50.00; H, 4.80; N, 16.66.

Found: C, 49.72; H, 4.56; N, 16.44.

(B) 3,4-Diaminobenzyl alcohol Six grams (0.035 mole) of 4-amino-3-nitrobenzyl alcohol, 95 ml. of tetrahydrofuran and 0.5 g. of Raney 6 2 Nickel were hydrogenated at 2.74 x 10 dynes/cm. at room temperature until 3 moles of hydrogen were absorbed. The -21318 catalyst was filtered and the filtrate was evaporated in vacuo to yield 4.83 g. (82 percent yield) of 3,4-diaminobenzyl alcohol, mp. 74-75°C.

Analysis C7HioN2° MW 138 Calcd: C, 60.85; H, 7.30; N, 20.28.

Found: C, 60.90; H, 7.15; N, 19.99.

(C) 2-Amino-5(6)-hydroxymethylbenzimidazole.

Two grams (0.014 mole) of 3,4-diaminobenzyl alcohol were dissolved in 40 ml. of methanol. To this solution was added a solution of 1.6 g.(0.014 mole) of cyanogen bromide in 10 ml. of methanol. After standing overnight at room temperature, the reaction mixture was evaporated to dryness in vacuo to give 3.4 g.(97 percent yield) of the hydrobromide salt of 2-amino-5 (6)-Rydroxymethyl benzimidazole.

Alternatively, this product may also be obtained from 4-amino-3-nitrobenzyl alcohol without isolation of the intermediate diamine after hydrogenation. The filtrate obtained after removal of the hydrogenation catalyst was treated with a solution of cyanogen bromide in methanol.

The product was isolated as described above.

(D) 2-Amino-5(6)-formylbenzimidazole.

Two hundred and fifty milligrams of 2-amino5(6)-hydroxymethylbenzimidazole were suspended in 7 ml. of acetone and the mixture was cooled in an ice bath. Jones reagent (0.3 ml) was added to the cold reaction mixture and the reaction was continued at 0°C. for about 5 minutes. The mixture was poured into 40 ml. of water. The aqueous mixture was extracted with chloroform (40 ml. portions). -224 3 318, The chloroform extract was washed with water and saturated sodium chloride solution and dried. The chloroform was evaporated in vacuo to leave a solid residue. The residue was recrystallized from ethyl acetate to yield 57 mg. of 2-amino-5(6)-formylbenzimidazole. The proton magnetic resonance spectrum indicates the correct product having a formyl group.

(E) 1-(Thiazolin-2-yl)-2-amino-5(6)-formylbenzimidazole.

IQ Sodium hydride, 355 mg. (7.4 mmoles), as a 50 percent mineral oil suspension was washed three times with n-pentane to remove the mineral oil. The washed sodium hydride was covered with 7 ml. of dimethylformamide (DMF).

A solution of 1.2 g. (7.4 mmoles) of 2-amino-5(6)-formyl15 benzimidazole in 20 ml. of DMF was added to the hydride suspension under anhydrous conditions. The reaction was stirred for 3 hours at room temperature to generate the anion. A solution of 895 mg. (7.4 mols) of 0-chloroethylisothiocyanate in dimethoxyethane (DME) was added to the reaction mixture and the reaction was stirred overnight.

The reaction mixture was evaporated to dryness in vacuo.

The residue was stirred with 140 ml. of ethyl acetate for 3 hours. The insoluble product was filtered and the filtrate was evaporated in vacuo to a residue. The residue was triturated with ethyl acetate and the mixture was centrifuged to collect more solid. The solids were combined and stirred with 50 ml. of water for several hours. The insoluble product was filtered to yield 1.1 g. of 1-(thiazolin2-yl)-2-amino-5(6)-formylbenzimidazole. -234-331 2 Analysis CHH10N4SO MW 242 Calcd: C, 53.64; H, 4.09; N, 22.75.

Found: C, 53.86; H, ->.20; N, 22.46.

Example 6 (A) 4-Acetamidoacetophenone One hundred grams of p-aminoacetophenone was added portionwise to 400 ml. of acetic anhydride. Pyridine was added to maintain a homogeneous solution. The reaction mixture was stirred for 2 hours at room temperature. The mixture was poured into 3.5 1. of cold water. The precipitated product was collected to yield 108.5 g. (93 percent) of 4-acetamidoacetophenone.

Analysis cioHllN02 MW 377 Calcd: C, 67.78; H, 6.26; N, 7.90.

Found: C, 68.03; H, 6.47; N, 8.02.

(B) 3-Nitro-4-acetamidoacetophenone Five grams of 4-acetamidoacetophenone were added portionwise to 25 ml. of red fuming nitric acid at 0°-5°C. After the addition was completed, the mixture was stirred for about 15 minutes. The reaction mixture was carefully poured over ice. The precipitated product was collected to yield 4.7 g. (75 percent) of 3-nitro-4-acetamidoaeetophenone.

(C) 3-Nitro-4-aminoacetophenone Sixteen grams of 3-nitro-4-acetamidoacetophenone in 160 ml. of concentrated sulfuric acid were stirred at room temperature for about one hour. The mixture was carefully poured into cold water and the precipitated product was filtered to yield 9.5 g. (73 percent) of 3nitro-4-aminoacetophenone. -244 3 3 Analysis CgHgN2O3 MW 180 Calcd: C, 53.33? H, 4.48; N, 15.55.

Found: C, 53.18; H, 4.33; N, 15.87.

(D) 2-Amino-5(6)-acetylbenzimidazole Four and one-half grams of 3-nitro-4-aminoacetofi 0 phenone were hydrogenated at 4.13 x 10 dynes/cm. in 145 ml. of ethyl acetate with 1 g. of platinum oxide and 3 g. of Raney nickel at room temperature. Three equivalents of hydrogen were absorbed in 5 hours. The catalyst was filtered. Three grams of cyanogen bromide was added to the filtrate and the mixture was stirred for about 24 hours. The hydrobromide salt of the product precipitated and was collected to yield 2 g. of 2-amino-5(6)-acetylbenzimidazole hydrobromide.

Analysis CgHgN3O. . HBr MW 256 Calcd: C, 42.21; H, 3.94; N, 16.41. Found: C, 42.43; H, 4.09; N, 16.35.

(E) 1-(Thiazolin-2-yl)-2-amino-5(6)-acetylbenzimidazole Five millimoles, 870 mg., of 2-amino-5(6)acetylbenzimidazole was dissolved in a mixture of 25 ml. of dimethoxyethane (DME) and 3 ml. of dimethylformamide by warming. The solution of the ketobenzimidazole was added dropwise with stirring to 240 mg. (5 mmole) of sodium hydride as a 50 percent mineral oil suspension in DME under anhydrous conditions. The reaction was continued for about 3 hours to complete the salt formation. Six hundred milligrams (5 mmole) of β-chloroethylisothiocyanate was added dropwise and the reaction mixture was stirred overnight at room temperature. The insoluble product was filtered. The crude product was boiled in a mixture of chloroform and -2543315( methanol. The insoluble product was collected, washed with water and dried. The yield of 1-(thiazolin-2-yl)-2-amino5(6)-acetylbenzimidazole was 300 mg. (23 percent).

Analysis ci2H12N4OS MW 260 Calcd: C, 55.37; H, 4.65; N, 21.52.

Found: C, 55.15; H, 4.72; N, 21.36.

Example 7 1-(Thiazolin-2-yl)-2-amino-5(6)-propionylbenzimidazole was prepared from 1 g. (5.3 mmole) of 2-amino-5(6)propionylbenzimidazole as described in Example 6 to yield 100 mg. (6.9 percent) of product, recrystallized from a mixture of chloroform and methanol.

Analysis ci3Hi4N4OS MW 274 Calcd: C, 56.91; H, 5.14; N, 20.42.

Found: C, 56.55; H, 5.21; N, 20.12.

Example 8 1- (Thiazolin-2-yl)-2-amino-5(6)-butyrylbenzimidazole was prepared from 1 g. (4.9 mmole) of 2-amino-5(6)butyrylbenzimidazole as described in Example 6 to yield 556 mg. of product, characterized by m/e 288, 245 (m=43 which corresponds to a propyl group).

Example 9 (A) 2-Chloro-l-nitro-5-thenoylbenzene.

To a slurry of 50.4 g. (0.25 mole) of 4-chloro3-nitrobenzoic acid in 500 ml. of benzene was added with stirring 35 g. (0.27 mole) of oxalyl chloride in 50 ml. of benzene. To the mixture was added 0.5 ml. of pyridine and the mixture was warmed and stirred until complete solution. The solvent was removed and the solid dried under vacuum. -264 3 3 ί & The solid was dissolved in 100 ml. of methylene chloride then added dropwise over 45 minutes to a mixture of 100 ml. of methylene chloride and 30 g. of aluminium chloride under nitrogen at 0 to 5°C. in an ice-alcohol bath. To the slurry was added 100 ml. of methylene chloride. The mixture was allowed to warm to room temperature (25°C.) for 1 hour and warmed with water until complete solution was obtained (about 45 minutes at 35-40°C). When the yellow precipitate began to form, the solution was cooled to 0°C., and to the solution was added dropwise at -5 to 0°C. with stirring 20 g. (0.24 mole) thiophene in 40 ml. of methylene chloride.

The red solution was allowed to warm to room temperature overnight, and then poured over ice. The crude product was extracted with methylene chloride. The organic layer.was washed with potassium hydrogen carbonate solution, dried and condensed under vacuum, dissolved in benzene, treated with carbon, filtered, and concentrated to dryness to yield 49.5 g. (74 percent) of 2-chloro-l-nitro-5-thenoylbenzene as a brown solid.

(B) 2-Nitro-4-thenoylaniline.

Sixteen g. (0.06 mole) of the product of the above paragraph was amminated with 3 ml. of ammonia in 72 ml. of methanol and 13 ml. of tetramethylene sulfone at 120°C. for hours. The solvent was removed under vacuum. To the residue was added 150 ml. of water, the solution was acidified with 1 ml. hydrochloric acid, filtered, washed with water, washed with diethyl ether, and dried to yield 11.5 g. (77 percent) of 2-nitro-4-thenoylaniline. -274331 & (C) 2-Amino-5(6)-thenoylbenzimidazole.

Eleven g. (0.044 mole) of 2-nitro-4-thenoylaniline in 80 ml. of methanol was reduced with 1 g. of 5 percent palladium-on-carbon in 10 ml. of tetrahydrofuran at room temperature for 19 hours. The solution was filtered and 4.7 g. (0.044 mole) of cyanogen bromide was added. The mixture was stirred for 2 hours, concentrated under vacuum, diluted with 200 ml. of water, filtered, and dried with potassium carbonate to yield 6 g. (56 percent) of 2-amino-5(6)-thenoylbenzimidazole.

(D) 1-(Thiazolin-2-yl)-2-amino-5(6)-thenoylbenzimidazole.

Five g. (0.02 mole) of 2-amino-5(6)-thenoylbenzimidazole was reacted by the procedure of Example 1 to yield 3 g. (45 percent) of 1-(thiazolin-2-yl)-2-amino-5(6)-thenoylbenzimidazole. m/e 328.

Example 10 One g. (0.003 mole) of l-(thiazolin-2-yl)-2amino-5(6)-thenoylbenzimidazole (prepared by the procedure of Example 9), 1.0 g. of hydroxylamine hydrochloride, and 50 ml. of methanol were heated at reflux for about 12 hours.

The reaction mixture was concentrated under vacuum, redissolved in methanol, and added to 50 ml. of water with 50 ml. of buffer solution (pH=7.00). The precipitated product was collected to yield 700 mg. (68 percent) of 1-thiazolin2-yl)-2-amino-5(6)-(α-hydroxyiminothienylmethyl)benzimidazole m/e 343. -28Example 11 A solution of 137 mg. of 1-(thiazolin-2-yl)-2amino-5(6)-propionylbenzimidazole (prepared by the procedure of Example 7), loo mg. of hydroxylamine hydrochloride, and 20 ml. of methanol was reacted according to the procedure of Example 3 to yield 55 mg. of 1-(thiazolin-2-yl)2-amino-5(6)-(α-hydroxyiminopropyl)benzimidazole, m/e 289.

Example 12 Three hundred mg. (i mmole) of 1-(thiazolin-2-yl)10 2-amino-5(6)-(α-hydroxyiminobenzyl)benzimidazole (prepared in Example 3) was added to 4.4 ml. of dimethylformamide with stirring. To this solution was added 54 mg. (1 mmole) of sodium methoxide. The yellow solution was stirred and 102 mg. (1 mmole) of acetic anhydride was added, and the solu15 tion stirred for 10 minutes. To the solution was added 52 ml. of water and 50 ml. of buffer solution (pH = 7.00). The precipitate which formed was filtered to yield 274 mg. (88 percent) of 1-(thiazolin-2-yl)-2-amino-5(6)-(a-acetoxyiminobenzyl)benzimidazole, m/e 379. 2q Example 13 A solution of 1.6 g. (0.005 mole) of 1-(thiazolin2-yl)-2-amino-5(6)-benzoylbenzimidazole in 200 ml. of methanol, 1.1 g. (0.005 mole) of carboxymethoxylamine hemihydrochloride, and 0.3 ml. (0.003 mole) of concentrated hydrochloric acid was refluxed for 16 hours. The mixture was concentrated under vacuum to one-fourth the volume, diluted with 100 ml. of water and 200 ml. of buffer solution (pH = 10.00) and stirred. A precipitate formed which was filtered, -2943312 and then recrystallized from ethyl acetate to obtain 0.6 g. of l-(thiazolin-2-yl)-2-amino-5(6)-(a-methoxycarbonyl methoxyiminoben zy1) henzimidazole.

Analysis MW 409 Calcd: C, 58.81; H, 4.44; N, 17.15 Found: C, 59.04; H, 4.39; N, 17.07 The pH of the filtrate was then adjusted to 4 and 0.9 g. of a second precipitate isolated as above to produce 1-(thiazolin-2-yl)-2-amino-5(6)-(a-hydroxycarbonylmethoxyiminobenzyl) benzimidazole.

Analysis C^gH^NgO^S-I^O MW 412 Calcd: C, 55.34; H, 4.37; N, 16.99 Found:. C, 55.48; H, 3.93; N, 16.54 Example 14 To 1.19 g. (5 mmoles) of 2-amino-5(6)-(1,3dithiolan-2-yl)benzimidazole in 10 ml. of dimethoxyethane was added 240 mg. (5 mmoles) of sodium hydride (50 percent in mineral oil) suspended in 5 ml. Of dimethoxyethane. The orange solution was stirred at room temperature for 45 minutes, then 605 mg. (5 mmoles) of chloroethylisothiocyanate in dimethoxyethane was added and the solution stirred overnight (16 hours), filtered, and evaporated to dryness. The residue was dissolved in methanol-methylene chloride and chromatographed on a 60 g. Woelm silica gel in ethyl acetate. The desired fractions were collected, washed twice with dimethyl ether and dried to yield 78 mg. of 1-(thiazolin-2-yl)-2-amino-5(6)-(1,3-dithiolan-2-yl)benzimidazole. -3043318 Example l‘j To a solution of 274 mg. of 1- (thiazolin-2-yl)2-amino-5(6,-propionylbenzimidazole (prepared in Example 7) was added 200 mg. of thiosemicarbazide and 1.0 ml. of IN hydrochloric acid in 40 ml. of methanol. The mixture was then treated according to the procedure of Example 4 to yield 169 mg. of 1-(thiazolin-2-yl)-2-amino-5(6)-(athiocarbamoylhydrazonopropyl)benzimidazole, m/e 347.

Example 16 (A) 5-(3-Nitro-4-acetamidophenyl)tetrazole.

A solution of 10.3 g. (0.05 mole) of 3-nitro4-acetamidobenzonitrile, 3.5 g. of sodium azide and 3.9 g. of ammonium chloride in 100 ml. of dimethylformamide was refluxed for 16 hours. The cooled reaction mixture was poured into 500 ml. of IN hydrochloric acid and diluted with 300 ml. of water. The yellow product precipitated and was collected to yield 10 g. (81 percent) of 5-(3-nitro-4acetamidophenyl)tetrazole, mp. 210-213 C°. (dec). (Β) 1(2)-Methyl-5-(3-nitro-4-acetamidophenyl)tetrazole. -(3-Nitro-4-acetamidophenyl)tetrazole, 31.7 g. (0.13 mole), was dissolved in 200 ml. of acetone. Twenty three milliliters (0.17 mole) of triethylamine was added to the reaction mixture. The mixture was stirred until it became homogeneous. Thirty milliliters of methyl iodide were added followed by the addition of another 20 ml. of methyl iodide after 12 hours at room temperature. The reaction was continued another four hours. The precipitated product was collected and the filtrate was concentrated to one fourth the original volume in vacuo. The total yield was 20 g. (59 percent) of an isomeric mixture of 1(2)-31 3 1-3 methyl-5-(3-nitro-4-acetamidophenyl)tetrazole.

Analysis giohioN6°3 2<>2 Calcd: C, 45.80; H, 3.84; N, 32.05 Found: C, 45.64; H, 3.84; N, 32.18 (C) 1(2)-Methyl-5-(3-nitro-4-aminophehyl)tetrazole Two grams of 1(2)-methyl-5-(3-nitro-4-acetamidophenyl)tetrazole were added to 20 ml. of concentrated sulfuric acid at room temperature. The tetrazole slowly went into solution and the mixture was stirred for about 2 hours. The acid mixture was poured carefully into 200 ml. of cold water. The precipitated product was collected to yield 1.6 g. (95 percent) of 1(2)-methyl-5-(3-nitro4-amino)tetrazole, mp. about 200°C.

Analysis CgHgNgO2 MW 220 Calcd: C, 43.64; H, 3.66; N, 38.17 Found: C, 43.37; H, 3.70; N, 37.89.

(D) 1(2)-Methyl-5-(3,4-diaminophenyl)tetrazole. Fourteen grams of l(2)-methyl-5(3-nitro-4aminophenyl)tetrazole were hydrogenated at 4.13 x 10^ dynes/cm. with 1 g. of palladium-on-carbon in 135 ml. of ethyl acetate and 350 ml. of absolute ethanol. After 2 hours three equivalents of hydrogen were absorbed. The catalyst was filtered and the filtrate was evaporated in vacuo to yield 12 g. (98 percent) of 1(2)-methyl-5-(3,4diaminophenyl)tetrazole.

Analysis CgH-^Ng MW 190 Calcd: C, 50.52; H, 5.30; N, 44.18 Found: C, 50.79; H, 5.57; N, 43.95. -3213 3 1 § (Ε) 1(2)-Methyl-5-(2-aminobenzimidazol-5(6)yl)tetrazole.

Cyanogen bromide, 3.2 g. (0.03 mole), was added to a slurry of 5.7 g. (0,03 mole) of 1 (2)-methyl-5-(3,4-diantinophenyl)tetrazole in 300 ml. of water and 30 ml. of methanol. The mixture was stirred for 12 hours and filtered. The filtrate was neutralized with potassium carbonate. The precipitated product was collected to yield 5.7 g. (88 percent) of 1(2)-methyl-5-(2-aminobenzimidazol-5(6)yl)tetrazole.

Analysis CgHgNg MW 215 Calcd: C, 50.23; H, 4.22; N, 45.56 Found: C, 49,56; H, 4.34; N, 44.06 (F) 1-(Thiazolin-2-yl)-2-amino-5(6)-[1(2)-methyltetrazol-5-yl]benzimidazole.

When an equivalent quantity of l(2)-methyl5-(2-aminobenzimidazole-5(6)-yl)tetrazole was reacted according to the procedure of Example 1, there was produced 1-(thiazolin-2-yl)-2-amino-5(6)-(1(2)-methyltetrazol-5yl]benzimidazole.

Example 17 The following intermediates and final product were prepared by the methods of Example 16. Alkylation of the tetrazole moiety with isopropyl iodide gave only a single isomer.

(A) l-Isopropyl-5-(3-nitro-4-aminophenyl)tetrazole, mp. 126-128°C., yield 71 percent.

Analysis 2θθ Calcd: C, 48.38; H, 4.87; N, 33.85 Found: C, 48.19; H, 4.93; N, 33.61 -3343318 (B) l-Isopropyl-5-(3,4-diaminophenyl)tetrazole, yield 70 percent.

Analysis C]_QHi4Ng Mw 218 Calcd: C, 55.03; H, 6.47; N, 38.50 Found: C, 55.23; H, 6.27; N, 38.73 (C) l-Isopropyl-5-[2-aminobenzimidazol-5(6)yl]tetrazole, mp. 232-233°C, yield 7.3 g. (86 percent) Analysis MW 243 Calcd: C, 54.31; H, 5.39; N, 40.30 Found: C, 54.56; H, 5.54; N, 40.53 (D) 1-(Thiazolin-2-yl)-2-amino-5(6)-(1-isopropyltetrazol-5-yl) benzimidazole.

Example 18 1-(Thiazolin-2-yl)-2-amino-5(6)-acetylbenzimidazole, prepared by the procedure of Example 6, was reacted with acetic anhydride to provide 1-(thiazolin-2-yl)-2acetamido-5(6)-acetylbenzimidazole.

The compounds of formula (I) exhibit a broad spectrum of antiviral activity. Not only are they especially effective in inhibiting the growth of echo virus, Mengo, Coxsackie (AO,21,B5), polio (types I, III, III) or rhinovirus (25 strains) but they also inhibit various types of influenza viruses such as Ann Arbor, Maryland B, Massachusetts B, Hong Kong A, Pr-8a and Taylor C (types A,B).

The ability of compounds coming within the scope of formula (I) to suppress the growth of different viruses in vitro is readily demonstrated by using a plaque suppression test similar to that described by Siminoff, Applied Microbiology 9(1), 66-72 (1961). The specific tests utilized are described in detail hereinbelow. -3443318 Test Methods African green monkey kidney cells (BSC-1) or Hela cells (5-3) were grown in 25 cc. Falcon flasks at 37°C. in medium 199 with 5 percent inactivated fetal bovine serum (FBS), penicillin ¢150 units 1 ml.) and streptomycin (150 meg./ml.). When confluent monolayers were formed, the supernatant growth medium was removed and 0.3 ml. of an appropriate dilution of virus (echo, Mengo, Coxsackie, polio, or rhinovirus) was added to each flask. After absorption for one hour at room temperature, the virus infected cell sheet was overlaid with a medium comprising one part of 1 percent Ianagar No. 2 (Ianagar is a Trade Mark) and one part double strength medium 199 with FSS, penicillin, and streptomycin which contains the drug at concentrations of 100, 50, 25, 12, 6, 3 and 0 micrograms per milliliter (mcg./ml.). The flask containing no drug served as the control for the test. The stock solutions of thiazolinyl benzimidazole compounds of formula (I) were made up in dimethylsulfoxide at a concentration of 104 mcg./ml. The flasks were incu20 bated for 72 hours at 37°C. for polio, Coxsackie, echo, and Mengo virus and 120 hours at 32°C. for rhinovirus. The influenza viruses, Ann Arbor, Maryland B, Massachusetts B, Hong Kong A, Pr-8a, and Taylor C (types Α,Β), were incubated for 72 hours at 37°C. using MDCK cells (Madin-Darby canine kidney cells). Plaques were seen in those areas where the virus infected and reproduced in the cells. A solution of 10 percent formalin and 2 percent sodium acetate was added to each flask to inactivate the virus and fix the cell sheet to the surface of the flask. The virus plaques, irrespec-3543318 tive of size, were counted after staining the surrounding cell areas with crystal violet. The plaque count was compared to the control count at each drug concentration.

The activity of the test compound was expressed as percentage plaque reduction, or percent inhibition. Alternatively, the drug concentration indicated by the symbol Ι^θ which inhibits plaque formation by 50 percent can be used as a measure of activity.

Test results are expressed in terms of Polio virus type I inhibition because the virus is easy to grow and consistent test results are obtained. However, the activity of the compounds of formula (I) was confirmed against other virus cultures such as Coxsackie (A9, A21, B5), echo virus (strains 1-4), Mengo, rhinovirus (25 strains) Polio (type I, II, III), and influenza viruses such as Ann Arbor, Maryland B, Massachusetts B, Hong Kong A, Pr-8A and Taylor C (types A,B). Test results for various thiazolinyl benzimidazole compounds are summarized in Table X below: In the table, column 1 gives the Example number from the previous chemical examples, column 2 gives the isomer in the 5(6) position, and columns 3-10 indicate the percent virus plaque reduction at drug dilutions from 0.75-100 micrograms per milliliter (mcg/ml). -36331 S Table I. Polio I Plaque Reduction of 1-(Thiazolin-2-yl)2-amino-5(6)-substituted-benzimidazoles I Drug Concentration (mcg/ml) * Percent Plaque Reduction in h- CM o o in o o CM o LD o © o r- H rd tn LD o O o ο σ» 00 σ> o o o cn rd rd rd n o © O © O LO o © O © © rd o rd rd rd I—1 rd ID o © © © O O rd O o o © O -4* © r-1 r—1 rd rd rd CM CM o O © © O LO O rd rd o o o © tn © I—1 rd rd rd rd LD r» © CM o o X r* O CJ LD o CM © o rd 0 CO © ι—1 rd rd ω +) rd * * * O *3* o O O * X r~ o m 00 o © O H 0 Ci o ι—1 rd rd W -P rd * * * o o o rd O o Ό X m O o o o O o 0 0 σ' O r—1 »—1 rd rd rd Ε -P rd * * P Φ £ LD \D LD LD LO LD LD LO r» ·«—* '·“* (0 in in in in in m in in H 0 2 1—} Qi £ in rd in ro © CM ch rd rd rd rd rd X w ο ρ P X •H £ P Φ e o ω -37' 13318 The 1-thiazolinylbenzimidazole compounds were tested both as pure compounds and as isomer mixtures. Both isomers inhibit virus growth, the 6-isomer generally being more active than the 5-isomer.

Compounds coming within the scope of formula (I) are able to suppress the growth of several viruses when added to a medium in which the virus is growing. The compounds of formula (X) can therefore be used in agueous solution, preferably with a surfactant, to decontaminate surfaces on which polio, Coxsackie, rhinovirus, and influenza viruses are present, such surfaces including hospital glassware, hospital working surfaces and similar areas used for the preparation of food.

Furthermore, the compounds can be orally administered to warm-blooded animals and humans in a dose of 1 to 300 mg./kg. of animal body weight. The administration cun be repeated periodically as needed. In accordance with general practice, the antiviral compound can be administered every four to six hours.

Preferably, the compounds of formula (I) are used in combination with one or more adjuvants suited to the particular route of administration. Thus, in the case of oral administration, the compound is modified with pharmaceutical diluents or carriers such as lactose, sucrose, starch powder, cellulose, talc, magnesium stearate, magnesium oxide, calcium sulfate, acacia powder, gelatin, sodium alginate, sodium benzoate and stearic acid. Such compositions can be formulated as tablets or enclosed in capsules for convenient administration. In addition, the -384331g compounds can be administered parenterally.

The compounds can also be mixed with a liquid and administered as nose drops or intranasal spray.

Claims (14)

1. •Claims :1. A compound of the general formula wherein R is hydrogen, or C^-C^ acyl; R^ is hydrogen, C^-Cj alkyl, C^-Cg cycloalkyl (as herein defined), (Cj-Cg cycloalkyl)methyl, 1-(Cj-Cg cycloalkyl)ethyl, thienyl or phenyl and m is 1 or R^ is 1-(C^-Cj alkyl)tetrazol-5-yl or l,3-dithiolan-2-yl, and m is 0; Z is oxygen, hydroxyimino, C^-C 4 alkoxyimino, C^-C 4 acyloxyimino, a-methoxycarbonylmethoxyimino, α-hydroxycarbonylmethoxyimino, or thiocarbamoy lhydrazono; P) R^—1C/——is at the 5 or 6 position; and n is 0, 1 or 2; subject to the limitations that R^ is other than C^-Cj alkyl or phenyl when R is hydrogen and Z is oxygen.

2. A compound according to Claim 1 wherein n is 0 or l, ici is 1 and Z is oxygen, hydroxyimino, C ± _ 4 alkoxyimino,C 1-4 acyloxyimino or thiocarbamoylhydrazono.

3. A compound of Claim 1 wherein R is hydrogen, n is 0, m is 1, and Z is oxygen. 40 433

4. A compound of Claim 1 wherein R is hydrogen, n is 0, m is 1, and Z is hydroxyimino.

5. 1-(thiazolin-2-yl)-2-amino-5(6)-thenoylbenz - imidazole.

6. 1-(thiazolin-2-yl)-2-amino-5(6)-(a-hydroxyimino 2-thienyl)benzimidazole.

7. 1-(thiazolin-2-yl)-2-amino-5(6)-(α-hydroxyimino propyl) benz imidazole.

8. 1-(thiazolin-2-yl)-2-amino-5(6)-(a-acetoxyimino benzyl)benzimidazole.

9. 1-(thiazolin-2-yl)-2-amino-5(6)-(a-hydroxyimino benzyl) benzimidazole.

10. A process for the preparation of a compound of formula (I) as claimed in Claim 1 which comprises reacting a compound of the general formula wherein R^ is hydrogen, C^C^ alkyl, C-^-Cg cycloalkyl (as herein defined), (C^-Cg cycloalkyl)methyl, l-tC^-Cg cycloalkyl)ethyl, thienyl or phenyl and m is 1 or is l-tC^C-j alkyl)tetrazol-5-yl or l,3-dithiolan-2-yl and m is 0 and Z' is oxygen with a base and a haloethylisothiocyanate of the formula X—(CH 2 ) 2 —NCS (IV) wherein X is chloro or bromo, optionally mono- or disubstituted on the C chain with methyl groups, optionally followed, where necessary, by reaction of the compound obtained with a substituted amine to obtain the compounds 5 of formula (I) wherein Z is other than oxygen, C^-C^ acyloxyimino or C^-C^ alkoxyimino, optionally followed by alkylation of the compounds of formula (I) where Z is hydroxyimino to provide the compounds of formula (X) where Z is alkoxyimino, and/or followed by acylation 10 to obtain the compounds of formula (I) wherein. R is Cj-C^ acyl and/or when Z is hydroxyimino to obtain compounds of formula (I) wherein Z is acyloxyimino.

11. A compound as defined in Claim 1, substantially as hereinbefore described with particular reference to 15 Examples 3-5 and 9-18.

12. A process as defined in Claim 10, substantially as hereinbefore described with particular reference to Examples 3-5 and 9-18.

13. A compound of formula (I) whenever prepared by 20 a process as defined in Claim 10 or 12.

14. A pharmaceutical formulation which comprises a compound of formula .(I) associated with a pharmaceutically acceptable carrier therefor.