CA1117949A

CA1117949A - Aminothiazoles

Info

Publication number: CA1117949A
Application number: CA000328805A
Authority: CA
Inventors: Joseph G. Lombardino
Original assignee: Pfizer Inc
Current assignee: Pfizer Inc
Priority date: 1978-06-02
Filing date: 1979-05-31
Publication date: 1982-02-09
Also published as: IT7923228A0; SE438333B; NL7904337A; MY8500318A; NO150760B; PL117515B1; PT69718A; GB2022085A; FI68820B; IL57450A; NZ190623A; NO150760C; DD144055A5; AR226285A1; FI68820C; DK150068C; IE791069L; HK66487A; GB2022085B; YU40997B

Abstract

Abstract A series of 2-aryl aminothiazoles and the pharmaceutically acceptable acid addition salts thereof having anti-inflammatory and immune regulant activity are disclosed. Preferred compounds include 2-phenethyl-amino-4-phenyl-thiazole, 2-phenethylamino-4, 5-diphenyl-thiazole, 5-methyl-2-phenethylamino-4-phenyl-thiazole, 2-thenylamino-4-phenyl-thiazole and 2-thenylamino-4-(p-fluorophenyl)-thiazole.

Description

r P.C. 6078 Novel Aminothiazoles This invention relates to novel substituted aminothia~oles useful for relieving inflammatory conditions and as immune regulants.
A number of compounds have been know~ in the art to be useful as anti-inflammatory agents, for example the cortico steroids; phenylbutazone, indomethacin and various 3,4-dihydro-4-oxo-2H-1,2-benzothiazine-4-carboxamide-l,l-dioxides, such as those disclos~d in 10 United States Patent No. 3,591,5~4. Accordingly, these compounds have been of therapeutic value in the treatment of arthritic and other inflammatory conditivns such as rhPumatoid arthritis. Such conditions have also been treated by administration of immunoregulatory 15 agents, such as levamisole, as described for example in Arthritis Rheumatism, 20~ 1445 (19773 and Lancet, 1, 393 (1976). In efforts to find new and improved therapeutic agents for the treatment of these conditions, it has now been found that the novel aminothiazoles 20 of the present invention have a particularly desirable combination of pharmacological properties, namely that they are active both as anti-inflammatory agents and as regulants of the immune response in the body.
Accordingly, they are of particular value in the 25 treatment of rheumatoid arthritis and other conditions where relief of the inflammation and regulation of the body immune response is desired.
The synthesis of a limited number of 2-aralkyl-aminothiazoles has been described in the art, for example 2-phenethylaminothiazole, Chem. Abs. 59, 1613e (1963); 2-benzylaminothiazole, J.A.C~S., 74, 2272 (1952) .. ~
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and 2-benzylamino-4-phenyl-thiazole, J. Ind. Chem. Soc., 4~, 57 (1967).
These articles do not, however, disclose any pharmacological activity of such compounds.
This invention relates to substituted aminothiazoles useful as anit-inflammatory agents and as regulants of the body immune response. More particularly, the novel compounds of this invention are those of the formula R ~ N
~ ~ NH-Rl S

and the pharmaceutically acceptable acid addition salts thereof, wherein R
is selected from -CH~ , -(CH2)2-X, -CH2-CH2-NH-X and -(CH2) Y, wherein X
is selected from phenyl and monosubstituted phenyl, said substituent being selected from alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms, chloro, bromo and fluoro; Y is selected from thienyl, monosubstituted thienyl, furyl and monosubstituted furyl, said substituent being selected from alkyl of 1 to 3 carbon atoms, chloro, bromo and fluoro; m is an integer from 1 to 2; R2 is selected from phenyl, thienyl and monosubstituted phenyl, said substituent being selected from alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms, chloro, bromo and fluoro; and R3 is selected from hydrogen, alkyl of 1 to 3 carbon atoms, phenyl and monosubstituted phenyl, said substituent being selected from alkyl of 1 to 3 carbon atoms, alkoxy of 1 to 3 carbon atoms, chloro, bromo, and fluoro. Preferred substit-uents for R2 are phenyl and p-fluorophenyl and for R3 are hydrogen and phenyl.

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A preferred group of compounds is that wherein Rl is -(C112)-X.
Most preferred are those compounds where X is phenyl or p-methoxy phenyl, R2 is phenyl or p-fluorophenyl, R3 is phenyl, methyl or hydrogen, including

2-phenethylamino-4-phenyl-thiazole, 2-phenethylamino-4,5-diphenylthiazole and 2-phenethylamino-5-methyl-4-phsnyl-thiazole.
A further group of interest is that wherein Rl is -(CH2)m-Y, espe-cially where m is 1. Preferred groups for Y are thienyl and furyl, espe-cially those compounds where R2 is phenyl or p-fluorophenyl and R3 is hydro-gen, methyl and phenyl.
Yet a further group of compounds are those wherein Rl is -CH ~ , preferred compounds being those where X is phenyl, R2 is phenyl and R3 is hydrogen or phenyl.
Another group of compounds of interest are those wherein Rl is -CH2-CH2-NH-X, especially those compounds where X is phenyl, R2 is phenyl and R3 is hydrogen.
Also embraced by the present invention are pharmaceutical composi-tions comprising a novel substituted aminothiazole of this invention, as de-scribed above herein, or a pharmaceutically acceptable acid addition salt thereof, together with a pharmaceutically acceptable carrier or diluent.
Preferred pharmaceutical compositions are those containing the preferred compounds described above and most preferably containing 2-phenethylamino-4-phenyl-thiazole, 2-thenylamino-4-~p-fluorophenyl)-thiazole or 2-(p-meth-oxyphenethylamino)-4-(p-fluorophenyl)-thiazole or pharmaceutically accept-able acid addition salts of these compounds.
Also claimed is a method of treating rheumatoid arthritis in a host which comprises administering to said host an effective anti-arthritic amount of a novel aminothiazole of this invention, especially those pre-ferred compounds described above and most preferably 2-phenethylamino-4-.
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phenyl-thiazole, 2-(p-methoxyphenethylamino)-4-(p-fluorophenyl)-thiazole or 2-thenylamino-4-(p-fluorophenyl)-thiazole or pharmaceutically acceptable acid addition salts thereof.
The novel aminothiazoles of this invention are prepared from an appropriately substituted N-aryl thiourea of the formula RlNHCNH2, where R
is as previously defined. The latter compounds are readily prepared from known and readily available amines of the formula RlNH2. For example~ when the group Rl is -~CH2)2-~, unsubstituted or appropriately substituted phen-ethylamines are employed. Corresponding thenyl or furyl analogs of these amines will be used to prepare compounds where Rl is -~CH2)m-Y. Where Rl is -CH , unsubstituted or substituted diphenylmethylamines are approp-riate starting materials, while when Rl is -CH2-CH2-NII-X, unsubstituted or substituted n-phenethylenediamines are employed. In the above, X, Y, n and m are as previously defined. The amine starting material is first converted to the hydrochloride or other hydrohalide salt by reaction with hydrogen chloride or other hydrogen halide, generally by bubbling the gas into a so-lution of the amine in an inert organic solvent, typically an ether such as diethyl ether, at a temperature of about -10C to about 10C. The amine hydrohalide salt is then reacted with ammonium thiocyanate or an alkali metal thiocyanate, such as potassium thiocyanate, in an inert organic sol-vent, generally an aromatic solvent such as bromobenzene, chlorobenzene, xylene and the like, to form the desired N-aralkyl thiourea. The reaction is preferably conducted in an inert atmosphere, for example under nitrogen, at a temperature of about 110C to about 250C, preferably 150C to 200C, for example at the :

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reflux temperature in bromobenzene. The reaction will generally be complete in about 30 minutes to about 6 hours depending on the temperature employed, generally in about l to 3 hours at 150 ~o 200C. In preparing the N-aralkyl thioureas as described above, it is usually found that some bis-aralkyl substituted thiourea is formedl but this can be readily separated from the desired monosubstituted product, for example by recrystallization. It has, however, been found that the reaction of substituted or unsubstitutad diphenylmethylamine hydrohalides and ammonium thiocyanate yields predominantly the bis-substituted thiourea, although smaller amounts of the monosubstituted compounds can be obtained in this reaction, and after separation can be used as starting material for the novel amino-thiazoles. It has, however, also been found that the bis-substituted thioureas can be used as starting material for the formation of he desired diphenylmethyl-aminothiazoles of this invention, the bis-substituted thiourea decomposing in situ to generate the monosubstituted compound.
The appropriate N~aralkyl thiourea is converted to the desired aminothiazole by reaction with an appropriately substituted ~ -halo ketone or aldehyde of the formula R2COCH(Z)R3, wherein R2 and R3 are as previously defined and Z is halo, preferably chloro or bromo. For example, when R2 is phenyl and R3 is hydrogen, ~ -bromoacetophenone may be employed, while when R2 and R3 are both phenyl an appropriate reagent is a desyl halide, for example 2-chloro-2-phenyl-acetophenone.
Other appropriate ~ -halo ketones or aldehydes will be readily selected in order to give the desired R2 and R3 substituents in the thiazole ring. The reaction is conducted in an inert organic solvent, typically an n-alkanol of 1 to 6 carbon atoms, preferably in absolute - : ' . :
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, L7~ 9 ethanol. Reaction temperatur~s between about 50 and 175C are employed, preferably the reflux ~emperature of the solvent. The reaction is preferably conducted in an inert atmosphere, for example, under nitrogen or another inert gas. The reaction is generally essentially complete in abou~ 1 ~o 15 hours depending on the temperature employed, for example in about 1 to 4 hours when using ethanol at reflux temperature. The desired compound will be obtained as the hydrohalide salt and the free base can then be prepared from the salt by conventional means, for example by contacting with an excess of a base such as an alkali metal hydroxide or carbonate, followed by extraction of the desired free base aminothiazole with a suitable organic solvent, for example an ether like diethyl ether.
The pharmaceutically acceptable acid addition salts of the novel aminothiazoles are also embraced by ~he present invention and are readily prepared by contacting the free base with the appropriate mineral or organic acid in either aqueous solution or in a suitable organic solvent. The solid salt may then be obtained by precipitation or by evaporation of the solvent. The pharmaceutically acceptable acid addition salts of this invention include, but are not limited to, the hydro-chloride, hydrobromide, hydroiodide, sulfate, bisulfate,nitrate, phosphate, acetate, lactate, maleate, fumarate, oxalate, citratel tartrate, succinate, gluconate, methane-sulfonate, and the like.
The novel aminothiazoles of this invention and their pharmaceutically acceptable acid addition salts are useful as anti-inflammatory agents and as regulants of the immune response in warm-blooded animals. The combination of anti-inflammatory activity and immune regulant activity is particularly valuable in the treatment of conditions such as rheumatoid arthritis and .

~3 ~L79~9 other diseases associated with immune deficiency and accompanied by inflammation. Thus, the compounds of the present invention act to relieve the pain and swelling associated with such conditions while also regulating the immune response of the subject and thereby alleviating the underlying immune disorder by maintaining immune competence. Accordingly, the present invention also embraces a method of treating rheumatoid arthritis in a warm-blooded animal by administering to the subject an effective anti-arthritic amount of an aminothiazole of the present invention or a pharmaceutically acceptable acid addition salt thereof. In accord with this method~
the compounds of the present invention may be administered to the subject in need of treatment by conventional routes, such as orally or parenterally, dosages in the range of about 0.10 to about 50 mg/kg body weight of the subject per day, preferably about 0.15 to about 15 mg/kg body weight per day being suitable.
However, the optimum dosage for the individual subject being treated will be determined by the person responsible for treatment, generally smaller doses being administered initially and thereafter gradual increments made to determine the most suitable dosage. This will vary according to the particular compound employed and with the subject being treated.
The compounds may be used in pharmaceutical preparations containing the compound or a pharmaceutically acceptable acid addition salt thereof in combination with a pharmaceutically acceptable carrier or diluent.
Suitable pharmaceutically acceptable carriers include inert solid fillers or diluents and sterile aqueous or organic solutions. The active compound will be present in such pharmaceutical compositions in amounts sufficient to provide the desired dosage amount in the range described above. Thus, for oral administration the .. ~ . .. . . . . . . . . . ..

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compounds may be combined with a suitable solid or liquid carrier or diluen~ to form capsules, tablets, powders, syrups, solutions ! suspensions and the like.
The pharmaceutical compositions may, if desired, contain additional components such as flavorants, sweeteners, excipients and the like. For parenteral administration the compounds may be combined with sterile aqueous or organic media to form injectable solutions or suspensions.
For example, solutions of the aminothiazoles in sesame or peanut oil, aqueous propylene glycol and the like may be used, as well as aqueous solutions of water-soluble pharmaceutically acceptable acid addition salts of the compounds. The injectable solutions prepared in this manner may then be administered intravenously, interperitoneally, subcutaneously or intramuscularly, with intravenous and interperitoneal administration being preferred. For local treatment of inflammation the compounds may also be administered topically in the form of ointments, creams, pastes and the like in accord with conventional pharmaceutical practice.
The activity of the compounds of the present invention as anti-inflammatory agents may be determined by pharmacological tests, for example the standard carrageenin-induced rat foot edema test using the general procedure described by C. A. Winter et. al., see Proceedings of the Society of Experimental Biology in Medicine, Volume 111, page 544 (1962). In this test, antiinflammatory activity is determined as the percent inhibition of edema formation in the hind paw of male albino rats (generally weighing about 150 to 190 grams) `- in response to a sub-plantar injection of carrageenin.
The carrageenin is injected as a 1% aqueous suspension 1 hour after oral administration of the drug, which is normally given in the form of an aqueous solution or suspension. Edema formation is then assessed 3 hours :
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after the carrageenin injection by comparing the initial volume of the injected paw and the volume after a 3 hour period. The increase in volume 3 hours after carrageenin injection constitutes the individual response.
Compounds are considered active if the response between the drug-treated animals (6 rats per group) and the control group, i.e. the animals receiving the v~hicle alone, is found to be significant on comparison with the results afforded by standard compounds like acetyl-salicyclic acid at 100 mg/kg or phenylbutazone at 33mg/kg, both by the oral route of administration.
The immune regulant activity of the compounds of the present invention may be determined by such pharmacological tests as the stimulation in vitro of lymphocyte proliferation of murine thymus cells cultured in the presence of Concanavalin A (Con A), employing the general evaluation procedure of V. J.
Merluzzi et. al., see Journal of Clinical and Experimental Immunology, Volume 22, page 486 (1975).
In this study, four different levels of lymphocyte stimulation assay (LSA) activity were established for the compounds undergoing evaluation, viz., those equal to Con A alone; those superior to Con A activity but less than levamisole, the standard compound of choice in this area; those having an activity equal to levamisole;
and those having an activity greater than levamisole.
Compounds are considered to be active for the present purposes if they are superior to Concanavalin A.
The present invention is illustrated by the following examples. However, it should be understood that the invention is not limited to the speci~ic details of these examples.
Example 1 Phenethylamine (479 grams, 3.96 moles, Eastman Scintillation Grade) was dissolved in 3500 ml of diethyl ' I
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ether and the solution was cooled to 0C. Dry hydroger.
chloride gas was bubbled through the stirred solution for 10 minutes and ~he resulting solids were filtered. The filtrate was then cooled and hydrogen chloride was bubbled through the solution for 10 minutes and the solids collected. This pxocedure was repeated until acidification of the filtrate with dry hydrogen chloride failed to yield any precipitate. The combined solids were dried in air and then over phosphorous pentoxide under vacuum to provide 514 grams (82%) of phe~ethylamine hydrochloride, m.p. 216-218C.
Phenethylamine hydrochloride (257 grams, 1.63 moles~
and ammonium thiocyanate (123.6 grams, 1.63 moles) were heated to 160C in 340 ml bromobenzene under nitrogen.
After heating for 90 minutes, the mixture was cooled to room temperature and then to 5C. This procedure was repeated with a further batch of 257 grams of phenethylamine hydrochloride. The combined solids obtained in the above reaction were stirred in 1.5 1 water and filtered. Recrystallization from isopropyl alcohol yielded 2~1.5 grams (45%) N-phenethyl thiourea, m.p. 132-134.
xample 2 N-phenethyl thiourea (225 grams, 1.25 moles) and ~-bromoacetophenone (250 grams, 1.25 moles, Aldrich Chem. Co.) in 1500 ml absolute ethanol were heatee to reflux temperature for 2 1/2 hours under nitrogen.
After reducing the solvent volume by 10%, the reaction mixture was cooled to room temperature and then ko 0C in an ice bath. The solids were filtered off, redissolved in 2,500 ml of absolute ethanol and heated to reflux.
The solvent volume was reduced to 2000 ml and the reaction mixture cooled to 0C. This procedure was repeated and after the second recrystallization the solids were collected and dried under vacuum over . : , ....................... : .

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-phosphorous pentoxide, yielding 365 grams (81%) of 2-phenethylamino-4-phenylthiazole hydrobromide, m.pr 169-17~C.
Analysis: Calcd for C17H16N2S Hsr: C, 56.50; H, 4.74;
N, 7.68 Found: C, 57.36; ~i, 5.04; N, 7.83.
- Example 3 N-phenethyl thiourea (140 grams, 0.779 moles) and desyl bromide (225 grams, 0.82 moles~ Eastman Chem. Col in 833 ml absolute ethanol were heated at reflux temperature for 2 hours under nitrogen, a further 300 ml of absolute ethanol being added during the reaction. The reaction mixture was cooled to 10C, the solids iltered, recrystallized from absolute e~hanol and dried over phosphorous pentoxide to yield 281.0 grams (83%) of 2-phenethylamino-4,5-diphenyl-thiazole hydrobromide, m.p. 171-174C.
Analysis: Calcd for C23H20N2S HBr: C, 63.14; H, 4.84;
N, 6.40 Found: C, 62~62; ~, 4.82; N, 6.48.
Example 4 N-phenethyl thiourea (2~0 grams, 0.011 moles) and ~-bromopropiophenone (2.34 grams, 0.011 moles, Aldrich Chem. Co.) in 10 ml absolute ethanol were heated to 2S re1ux temperature for 90 minutes under nitrogen. The ethanol was then removed under vacuum, excess ethyl acetate added and the solids filtered and dried over phosphorous pentoxide. Recrystallization from absolute ethanol yielded 2.86 grams (70%) of 5-me~hyl-2-phenethylamino-4-phenylthiazole hydrobromide, m.p.
172-175C.
Analysis: Calcd for C18H18N2S HBr: C, 57.59; ~, 5.10;
N, 7.46 Found: C, 57.67; H, 5.11; N, 7.39.

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~5 Following the proc~durPs of Examples 1 and 2, hydrohalide salts of the following compounds were prepared:

~ N

5 Salt X ~ ~ _.p.C
HBr phenyl p-methoxyphenyl hydrogen 135~139 HCl phenyl p-fluorophenyl hydrogen 163~165 ~sr p-bromophenyl phenyl hydrogen 171-174 HBr p-bromophenyl phenyl methyl 150-151.5 Hsr p-methoxyphenyl phenyl hydrogen 169-171 Hsr p-methoxyphenyl phenyl methyl 149-150.5 I~sr p-methoxyphenyl phenyl phenyl 201-205 HCl p-methoxyphenyl p-fluorophenyl hydrogen 156-158 Exam~le 6 Benzylamine hydrochloride l90 grams, 0.6 moles, Pfaltz & Bauer Co.) and ammonium thiocyanate (S0 grams, 0.66 moles) in 130 ml bromobenzene were heated to 155C
for 20 minutes to form a yellow-white suspension. After cooling the Eiltered solids were washed three times with water and three times with isopropyl alcohol.
Recrystallization from isopropyl alcohol and drying over phosphorous pentoxide yielded 38.26 grams (38%) of N-benzyl thiourea, m.p. 160-163C.

N-benzyl thiourea (2.0 grams, 0.012 moles) and ~-chloro-p-fluoroacetophenone (2.07 grams, 0.012 moles, Aldrich Chem. Co.) in 15 ml of absolute ethanol were heated to reflux for 2 hours under nitrogen. After cooling the filtered solids were washed with diethyl ether and dried over phosphorous pentoxide, yielding

3.47 grams ~91%) 2-benzylamino-4-(p-fluorophenyl)-," ' ` ' ' ~7~

thiazole hydrochloride, m.p. 192-195C.
Analysis Calcd- for C16~I13N2SF HCl: C, 59.90;
H, 4.40; N, 8.73 Found: C, 59.64; H, 4.38; N, 8.62 Example 8 Following the procedures of ~xamples 6 and 7, hydrohalide salts of the following compounds were prepared:

N

R3 ~ ~ NH-CH2-X
Salt X ~ ~ m.p.C
HBr phenyl phenyl phenyl 250-252 HBr phenyl p-methoxyphenyl hydrogen 155-157 HBr phenyl p-chlorophenyl hydrogen 211-212 HBr phenyl phenyl methyl 157-160 7/8 HBr phenyl 2,5-dimethoxyphenyl hydrogen 159-161 HBr phenyl p-methylphenyl hydrogen 155-lS9 HBr phenyl thienyl hydrogen 100 7/8 HBr p-fluorophenyl phenyl hydrogen 84-8S
- HBr p-fluorophenyl phenyl phenyl 225~227 HCl p-fluorophenyl p-fluorophenyl hydrogen 154-158 ` 20 HBr p-chlorophenyl phenyl hydrogen 176-180 HBr p-chlorophenyl phenyl methyl 148~151 Example 9 ~` 2-thenylamine (30 grams, 0.265 moles, Fairfield Chemical Co.) was dissolved in 400 ml of diethyl ether and cooled to 0C in an ice bath. Dry hydrogen chloride gas was bubbled through the solution for 5 minutes. The ; resulting solids were filtered and dried over phosphorous pentoxide to yield 26.7 grams (61%) of 2-thenylamine hydrochloride, m.p. 186-190C.
302-thenylamine hydrochloride (13.35 grams, 0.089 moles) and ammonium thiocyanate ~7.4 grams, 0.089 moles) .~

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in 20 ml bromobenzene were heated to reflux temperature for 90 minutes. The reaction mixture was cooled and the filtered solids washed three times with water.
Recrystallization from chloroform and drying over phosphorous pentoxide yielded 5.0 grams (33~ of N-thenyl thiourea, m.p. 99-101C.
Analysis: Calcd for C6H8N2S2: C, 41.83; ~, 4068; N, 16.26 Found: C, 41.56 H, 4.58; N, 16.07.
Example 10 N-thenyl ~hiourea ~2.0 grams, 0.0116 moles) and ~-bromoacetophenone ~2.3 grams~ 0.0116 moles, Aldrich Chem. Co.) in 15 ml absolute ethanol were heated to reflux temperature for 90 minutes under nitrogen. The reaction mixture was cooled and the ethanol removed lS under vacuum. On dissolving the residue in hot isopropyl alcohol and diluting with diethyl ether, an oil was formed. The diethyl ether was decanted, the oil dissolved in a small amount of ethanol and cooled. The resulting solids were filtered and dried over phosphorous pentoxide, yielding 3.20 grams (78~) of 2-thenylamino-4-phenyl-thiazole hydrobromide, m.p.
115-118C.
Analysis: Calcd for Cl4Hl2N2S2 HBr: C, 47.58; H, 3.71;
N, 7.93 Found: C, 47.75; H, 3.74; N, 7.90.
Exam~le 11 N-thenyl thiourea ~0.80 grams, 0.0046 moles) and ~-chloro-p-fluoroacetophenone (0.80 grams, 0.0046 moles, Aldrich Chem. Co.) in ll ml absolute ethanol were heated at reflux temperature under nitrogen for 90 minutes. After cooling, the ethanol was removed under vacuum and the solids triturated with ethanol, iltered and vacuum dried over phosphorous pentoxide, yielding 0.848 grams (56%) of 2-thenylamino-4(p-fluorophenyl)-thiazole hydrochloride, m.p. 184-187C.

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~15-Analysis: Calcd for C14HllN2S2F HCl: C, 51.45; H, 3.70;
N, 8.57 Found: C, 51.41; H, 3.63; N, 8.39.
x mple 12 Followiny the procedures of Examp~es 10 and 11, hydrohalide salts of the following compounds were prepared:

R3 ~ ~ 2 ~ ~
Salt R R mOp.C
HBr p-methoxyphenyl hydrogen 154-158 ~Br phenyl methyl 179.5-181.5 HCl thienyl hydrogen 137-142 Example 13 Furfurylamine (25.0 grams, 0.257 moles, Pfaltz &
Bauer Co.) was dissolved in 1300 ml diethyl ether and cooled to 0C in an ice bath. Dry hydrogen chloride gas was bubbled through the solution until no further precipitation occurred. The solids were filtered and dried in vacuum over phosphorous pentoxide to yield 33.46 ~97%) of furfurylamine hydrochloride, m.p.
147-149C.
Furfurylamine hydrochloride (33.46 grams, 0.250 moles) and ammonium thiocyanate (38.14 grams, 0.501 moles) in 71 ml bromobenzene were heated under nitrogen at reflux temperature for 20 minutes and then cooled to room temperature. The reaction mixture was mixed with a solution of 125 ml water and 100 ml ethyl acetate and left at room temperature overnight. The mixture was then diluted to give 500 ml ethyl acetate and 350 ml water and the aqueous layer separated. The organic layer was washed with water and dried over sodium sulfate. After filtration, the organic layer was . , :
. .
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7~9 evaporated to dryness and bromobenzene removed under vacuum. The resulting solids were ground in a mortar and pestle and the fine particles stirred in diethyl ether to remove residual bromobenzene. The solids were then filtered, washed with diethyl ether and vacuum dried over phosphorous pentoxide, yielding 12.06 grams t30%) of N-furfuryl thiourea, m.p. 80-91C.
Analysis: Calcd for C6H8N2OS: C, 46.14; H, 5.16; N, 17.93 Found: C, 46.91; H, 4.90; N, 17.57.
~10 Example 14 N-furfuryl thiourea (0.82 grams, 0.005 moles) and ~-bromopropiophenone [1.07 grams, 0.005 moles, Aldrich Chem. Co.) in 11 ml absolute ethanol were heated to reflux temperature under nitrogen for 3 hours. After cooling to room temperature, the solvent was removed under vacuum to give a thick brown oil, which was triturated with five 35 ml portions of refluxing ethyl acetate. The ethyl acetate was reduced in volume to about 25 ml and cooled to room temperature. The precipitated solids were filtered, washed with ethyl acetate and vacuum dried over phosphorous pentoxide, yielding 0.585 grams t33~) of 2-furfurylamino-S-methyl-

4-phenyl-thiazole hydrobromide, m.p. 150-153C.
Analysis: Calcd for C15H14N2OS.HBr: C, 51.29; H, 4.30;
N, 7.97 Found: C, 51.97; H, 4.47; N, 8.42.
Example 15 Following the procedure of Examples 13 and 14, hydrohalide salts of the following compounds were prepared:

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~7~49 Salt ~ ~ mpC
HBr phenyl hydrogen 123-126 ~Br phenyl ph~nyl 192-194 Example 16 Diphenylmethylamine (25.0 grams, 0.136 moles, Matheson, Coleman ~ Bell Co.) was dissolved in 660 ml of diethyl ether and cooled to 0C. Dry hydxogen chloride gas was bubbled through the solution for 10 minutes, during which time an additional 300 ml of diethyl ether was added to the mixture. The precipitate was filtered, washed with diethyl ether and vacuum dried over phosphorous pentoxide, to yield 28.3 grams (95%) diphenylmethylamine hydrochloride, m.p. 303-310C
(decomposes).
Diphenyl~ethylamine hydrochloride ~28.3 grams, 0.129 moles) and ammonium thiocyanate (9.81 grams, 0.129 moles) in 37 ml bromobenzene were heated at reflux temperature under nitrogen for 3 1/2 hours and then cooled to room temperature. The solids were filtered and triturated twice with 200 ml water. The solids were then dissolved in 850 ml ethanol, filtered and evaporated to a volume of about 350 ml. After cooling, the solids were filtered, washed with ethanol and vacuum dried over phosphorous pentoxide to yield 14.72 grams (56~) of N,N'-bis-(diphenylmethyl) thiourea, m.p.
216-217.5C.
Analysis: Calcd for C27H24N2S: C, 79.37; H, 5.92;
N, 6.86 Found: C, 79.84; H, 6.05; N, 6.93.
Example 17 N,N'-bis-(diphenylmethyl) thiourea (1.21 grams, 0.005 moles) and desyl chloride (1.21 grams, 0.005 moles, Aldrich Chem. Co.) in 11 ml absolute ethanol were ~-heated to reflux temperature under nitrogen for 3 hours.
After cooling, the reaction mixture was evaporated - , ,' `:'. ., ~ . '`, ~ . ' . -.. :::
- : . . : :

~L7~ 9 to dryness, the resulting oil being mixed with about 40 ml diethyl ether. The solids were filtered, cooled with diethyl ether and vacuum dried over phosphorous pentoxide, yielding 1.01 grams ~75%) of 4,5-diphenyl-2-diphenylmethylamino-thiazole hydrochloride, m.p.
195-1~8C.
Analysis: Calcd for C28H22N2S HCl: C, 73.91; H, 5O09;
N, 6.16 Found: C, 73.12; H, 5~28; N, 6.06.
Example 18 Following the procedures of Examples 16 and 17, 4-phenyl-2-diphenylmethylamino-thiazole hydrobromide was prepared, m.p. 166-168C.
Example 19 N-phenylethylenediamine (25 grams, 0.184 moles, Aldrich Chem. Co.) was dissolved in diethyl ether, cooled to 0C and dry hydrogen chloride gas bubbled through the solution until no more precipitation occurred.
The filtered solids were dried over phosphorous pentoxide, yielding 31.2 grams (98%) N-phenylethylene-diamine hydrochloride.
N-phenylethylenediamine hydrochloride (31.2 grams, 0.149 moles) and ammonium thiocyanate (11.3 grams, 0.149 moles) in 31 ml bromobenzene were heated to reflux temperature under nitrogen for 2 hours. Ater cooling, the resulting solids were filtered off and the bromobenzene was removed from the iltrate under vacuum.
The resulting solids were stirred in 250 ml of water, filtered and dissolved in hot isopropyl alcohol. After cooling, the solids were filtered and dried over - phosphorous pentoxide, yielding 2.8 grams (8%) of N-(2'~
anilinoethyl)-thiourea, m.p. 137-140C.
Analysis: Calcd for CgH13N3S: C, 55.35; H, 6~71;
N, 21.52.
Found: C, 55.64; H, 6.757 N, 21.03.

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Example 20 N-(2'-anilinoethyl)-thiourea (0O90 grams, 0.0046 moles) and~-bromoacetophenone (0.92 grams, 0.0046 moles, ~ldrich ChemO Co.) in 6 ml absolute ethanol were hea~ed to reflux under nitrogen for 2 hours. After cooling the reaction mixture, the solvent was removed under vacuum.
The resulting oil was dissolved in hot isopropyl alcohol, filtered and cooled. The solids were filtered and dried over phosphorous pentoxide, yielding 1.25 grams (73.5~) 2-~2'anilinoethylamino)-4-phenyl-thiazole, mOp. 161-165C.
Analysis: Calcd for C17H17N3S.HBr: C, 54.24; H, 4.82;
N, 11.16.
Found: C, 54.51; H, 4.59; N, 11.02.
Example 21 Following the procedures of Examples 19 and 20, hydrohalide salts of the following compounds were prepared:

R3 ~ ~ -NH-C~2-C~2-N~
Salt ~ ~ mpC
~Cl phenyl phenyl 139-143 HBr phenyl methyl 133-136 Example_22 The immune regulant activity of the aminothiazoles described in Examples 2, 3, 4, 5, 7, 8, 10, 11, 12, 14, 15, 17, 18, 20 and 21 was evaluated by determining their ability to stimulate, in itro, the lymphocyte proliferation of murine thymus cells cultured in the presence of Concanavalin A (Con A) by employing the procedure of V. J. Merluzzi et. al., as essentially described in the Journal of Clinical and ~xperimental Immunolo~, Vol. 22, p. 486 (1975~. The cells were derived from male C57Bl/6 mice of from 6-8 weeks age, . .
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~20-purchased from the Jackson Laboratories of Bar Harbor, Maine and the Con A was obtained from Sigma Chemicals of St. Louis, Missouri. Each cell culture (consisting of 0.10 ml thymus cells stock solution, 0.05 ml of Con A
stock solution and 0.05 ml of drug solution) was performed in quadruplicate and cellular proliferation was measured, after 48 hours of incubation at 37~C., by pulsing each culture with 3H-thymidine (0.01 ml of specific activity 1.9 C/mM, obtained from Schwarz-Mann, Inc. of Orangeburg, N.Y.) and then determining the incorporation of 3H-~hymidine into cellular desoxyribonucleic acid (DNA) by an assessment of radioactivity using a liquid scintillation counter.
The resul~s obtained in this manner are expressed quantitatively in terms of the average counts per minute (cpm) of 3H-thymidine incorporated at the drug level with maximum activity by the quadruplicate cell cultures.
These quadruplicate determinations are employed at eight different concentrations of drugs in the range 0.02 to 50~g/ml. The highest cpm value obtained is employed in the scoring system. On this basis, four different levels of activity were established in the present lymphocyte stimulation assay (LSA) and these are defined in the manner hereinafter indicated, viz., those levels equal to Con A alone (6,000 ~ 300 cpm) were assigned a negative value or score of zero; those superior (10,000 + 700 cpm) to Con A activity but less than levamisole were scored as ~; while those equal to levamisole l~2,000 + 900 cpm) were scored as ~ and those having an activity (27,000 1 1,000 cpm~ greater than levamisole were scored as ~++. The LSA activity for the compounds described in the above Examples was +~ in each case.
E~ple 23 The anti-inflammatory activity of aminothiazoles of this invention was determined using the standard ,: , ,, -21~

carrageenin-induced rat foo~ edema test, according to the procedure essentially as described by C. A . Winter et. al., and reported in the Proceedings of the Society for Experimental Biology and Medicine, Vol. 111, p. 544 (1962). The compounds were administered orally in the form of their previously reported hydrohalide salts at a dose level of 33 mg/kg. The results obtained in this manner are presented in the table below in terms of the p~rcent inhibition of edema formation afforded by each test compound as compared to the non-drug treated control (i.e., aqueous solution with no compound~:
R

2\~___N
R3 ~ ~ NH R
S HZ
% Inhibition of HZ ederna (33 mg/kg, p.o.) benzyl phenyl phenyl HCl 33 4-fluoro- phenyl hydrogen HBr 41 benzyl 2-thenyl 4-fluorophenyl hydrogen HBr 49 2-phenethyl phenylhydrogen HBr 47 2-phenethyl phenylphenyl HBr 48 4-methoxy- 4-fluoro-hydrogen HBr 29 phenethyl phenyl :, `' ' ' ' , ' ' ' :"' "' - : :
: ,

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of a compound of the formula I

wherein R1 is selected from the group consisting of , -(CH2)2-X, -CH2-CH2-NH-X and -(CH2)mY, wherein X is selected from the group consisting of phenyl and monosubstituted phenyl, said substituent being selected from the group consisting of alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms, chloro, bromo and fluoro;
Y is selected from the group consisting of thienyl, monosubsti-tuted thienyl, furyl and monosubstituted furyl, said substituent being se-lected from the group consisting of alkyl of 1 to 3 carbon atoms, chloro, bromo and fluoro;
m is an integer from 1 to 2;
R2 is selected from the group consisting of phenyl, thienyl, and monosubstituted phenyl, said substituent being selected from the group con-sisting of alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms, chloro, bromo and fluoro;
and R3 is selected from the group consisting of hydrogen, alkyl of 1 to 3 carbon atoms, phenyl and monosubstituted phenyl, said substituent being selected from the group consisting of alkyl of 1 to 3 carbon atoms, alkoxy of 1 to 3 carbon atoms, bromo, chloro and fluoro, characterized in that an appropriately substituted N-aralkyl thiourea of the formula , or, if desired when R1 is , a bis-substituted N-aralkyl thio-urea of the formula , where R1 and X are as previously defined, is reacted with an alpha-halo carbonyl compound of the formula R2COCH(Z)R3, wherein R2 and R3 are as previously defined and Z is halo, and, if desired, converting the compound of formula I to a pharmaceutically acceptable acid addition salt.

2. A process according to Claim 1 wherein the reaction is conducted in an n-alkanol of 1 to 6 carbon atoms and a temperature between 50° and 175°C.

3. A process according to Claim 2 wherein the n-alkanol is ethanol.

4. A process according to Claim 3 wherein R1 is -(CH2)2-X.

5. A process according to Claim 4 wherein X is phenyl, R2 is phenyl and R3 is hydrogen.