US2328594A - Compo und - Google Patents

Description

. Patented 7 hydrochloride. These salts have the following 30 UNITED 1 STATES PATE T oFFicE j amass I 6 goraition, New York, N. Y., a corporation or New or i No Drawing. Application April 1, 1937. Serial No. 134,334

' 36 Claims; (t1. 260-251) This invention relates to the production of have been numbered as shown in the structural antineuritic compounds and, particularly, to the formula given hereinabove to designate the posisynthesis of vitamin Bi, salts thereof, and retions or any attached groups or elements. It is lated products having the essential physiological tobe understood that when the term pyrimethyP' properties of vitamin B1. This application is a is used herein or in the annexed claims to definecontinuationin part of our copending applications a compound, it means that the group or element Serial No. 85,350, filed June 15, 1936, and Serial iollowing this term is attached to the CH: group No. 94,430,1lled August 5, 1936. located in the 5-position on the pyrimidine ring The isolation and structure of vitamin .Biare portion of the compound. It will be observed that referred to in the following articles: Jr. Am. 10 in vitamin B1, the methyl group and the amino Chem. Soc., vol. 57, pp. 229, 517, 536, 1093, 1751, group are attached to thepyrimethyl groupin the v 1849 and 1887 (1935) ;-vol. 58, pp. 1063, 1504 and 2 and 6 positions, respectively, and that hydrogen 1803 (1936) vol. 59, p. 216 (1937). is in the 4 position.

v The present invention relates to methods by The other radical entering intothe coupling which vitamin B1 and kindred compounds maybe reaction is a substituted thiazole nucleus, the synthesized. These syntheses make available nucleus having the structure indicated by the folvital substances which may be incorporated in lowing formula: l pharmaceutical products and in foods deficient in vitamin B1. l, An object of the invention is to provide syn- -/4 2 thetic vitamin 131, its salts and related compounds 1 havingf the essential physiological, pi'operties (I:

thereo Another object o! the invention is to provide From an examination of the formula given hereeflective and reliable processes for the production mgbove for the acid salts of vitamin it is vitamin its and related compmmds dent that the thiazole nucleus contained in the having Similar physiological reac i n natural vitamin has attached thereto a hydrogen Vitamin B1 is obtained from natural sources in atom in the 2 m a methyl group in t 4 the form of its acid salts usually as the chloride position and afi-hydroxy-ethyl group in the 5 position. The basic compound having these attached groups is described in Patent No. 2,134,015,

general structure v N: NH. (i=1 H o 'I'hiazole compounds. Acids add directly to this CH 1; 0 C c H 3 thiazole to form salts thereof and these salts may s be used in the syntheses instead oi. the base,'ii! 1k desired.

v v For the sake of clarity the following descrip- A 1 j tion will, in general, beconflned tothe utilization .in which X is an' anion and HX 'is an acid,.the oi 2-methyl-6-amino-pyrimethyl compounds and anion portion or which may or may not be the .3 d-methyl-ti-p-hydroxy-ethyl thiazole inthe varisameas theone representedb x. ous' coupling reactions embodying the invention, The syntheses embodying this invention come althoughit is to be understood that the invention prise the coupling of two distinct. radicals or is not'limited'to these particular pyrimethyl and groups to term the vitamin or other closely allied thiazoie derivatives. I substances. One of these groups is a derivative 0! it has been found that one of the instrumentalpyrimidine having the constitution indicated 1: itieg by which the pyrimethyl radic can. b the following formula:

N=C- 1 methyl ester, such as 2-methyl-6-amino-pyri- 011, granted October 25, 1938, to R. R. Williams, ior

coupled toathiazole group is a salt of a pyri methyl-bromide hy ro i'omide, which has vthe l1 s 11 We t e int ew has'been termed the pyrimetbfl m d" v i GE's-1!} -cn,mthe Mm h pyrimidine ring portion thereof a -.-n

Acid salts or pyrimethyl esters or thi general type may be coupled with a thiazole nucleus according to the following reaction:

Antineuritic compound in these equations X represents an acid radical and m is an acid. In the reaction which cc curs, it will be observed that the pyrimethyl porticn and the acid radical portion of the ester, represented by the symbol X, both unite with the nitrogen atom of the thiazole to produce a quaternary thiazolium compound.

It has been found that efiective results may be obtained by first producing a mixed ether such, tor example, as 2-methyl-6-amino-pyrlmethylethyl ether or 2-methy1-6-pyrimethyl-methyl ether and to obtain acid esters therefrom having the formula:

has

in which X is an acid radical or element in nonionic combination and H2? is an acid, the anion portion of hich may or may not be the same as the acid radical represented by X. The term acid radical as used herein is intended to denote not only a group of elements which act as a single element, e. g. the sulphate radical, but also elements, such as the halogens, which are acidic. The invention contemplates the reaction of a pyrimethyl ester of this type with a thiazole com= pound, such as 4-methyl-5-,B-hydroxy-ethyi thiazole, or with a salt thereof, to produce a salt of vita in B1 or a closely related compound which gaisfithe essential physiological properties of vita- Among the pyrimethyl esters and acid salts thereof which may be employed in practicing the invention, there may be mentioned the bromide, acetate, lactate, benz'oate, sulphate, phosphate, p-tcluene sulphonate, benzene sulphonate and ,6- naphthalene sulphonate esters and acid salts thereof. A pyrimethyl ester of this type constitutes a means by which the pyrirnethyl radical may be caused to unite with a thiazole nucleus, and a pyrimethyl ester may therefore be described as a. reactive Pyrlmethyl compound, the term reactive, as used herein, referring to the ability of the compound to react with a. thiazole nucleus to produce a. quaternary thiazolium derivative. It is further to be understood that the term reactive pyrimethyl compoun means a compound having a. reactive group attached to the methylene group in the 5-pcsition on the pyrimidine ring portion thereof.

Substances known to have antineuritic potency have been found to have certain substituents in certain positions in the molecules making up the :antineuritic substances. Thus, for example, an-

tincurltlc properties have been found in com:

pounds having a pyrimethyl group coupled with a. thlazole group in which a methyl group is attached in the 2 position and an amino group in the 6 position with respect to the pyrimethyl portion of the compound and a methyl group is attached in the 4 position and a fi-hydroxy-ethyl group in the 5 position of the thi'azole portion of the compound.

However, instead of the E-fl-hydroxy-ethyl group, a functional derivative thereof may be employed. Thus, compounds having the general formula:

can be obtained, wherein X is an acid radical, IE

is an acid and Z is a functional derivative of an ferred, however, to employ a, thiazole derivative having the hydroxy group already present therein in the proper position.

Instead of forming a pyrimethyl ester and separating it as a distinct compound a, mixture of pyrimethyl alcohol or a. pyrimethyl ether and an acid may be reacted directly with the appropriate thiazole, the important consideration being the use of a substance or a mixture which contains and will yield the pyrimethyl group in reactive condition. It is probable that such ccndensations of pyrimethyl alcohol, ether or amine with a thiazole in the presence of an acid proceed by the intermediate formation of a. pyrimethyl ester of the acid. In carrying out the reaction, conditions should be chosen so as to supply an acid. radical in order that the pyrimethyl radical and the acid radical may unite with the nitrogen atom. of the thiaz'ole compound to produce an antineuritic compound having the structure outlined above. The coupling reaction should preferably be carried out under acid conditions for the added reason that the antineuritic compounds produced are less stable under alkaline or neutral conditions. Also, because of the greater stability of their salts it has been found most-advantageous to prepare and administer the antineuritic compounds in the form of their acid salts which have structures closely resembling that given hereinabove for the acid salts of vitamin B1.

To illustrate the principles of the invention, specific examples will be given describing the coupling of d-methyl-fi-fi-hydroxy-ethyl thiazole with the following .Z-methyl-G-amino-pyrimethyl esters: bromide, acetate, lactate, benzoate, sulphate, phosphate, nitrate, benzene sulphonate, ptoluene sulphonate and B naphthalene sulphopate.

This description will include a disclosure of a. series of useful intermediate compounds containing the pyrimethyl radical from which the above esters may be prepared, one group comprising the ethers having the general formula:

oxy pyrimidine in the former applications will be 2-methyl-6-oxy pyrimethyli designated hereinas ethyl ether.

A description of the process for making 2- 2,828,594 wherein R and R. are aibi or aralkyl radicals (methyl, ethyl, propyl, benzyl, a o J2-CH3OCHCH| 7 etc). Byreplacingtheo-oxyradicalofthiscom 'pouniiwithaB-aminoradicalandtheOli'. Y

group with an acid radical, e. g. the sulphate or a 5 m -i m r s sulphonate or bromine, a compound is produced .N=c-c t 3 :3 gg i with 3 W19 4 Ont-4| d-cmocmcm A In the above mentioned copendinz mplications I Seriall 85.3%:1 and SerialgNo. a com- 1 z-methyl-ti-chlor-pryimethyl-ethylether .poun. sna therein as-me l-ethouymeth'yl-G-oxy pyrimidine,- and a method of pre-' N c paring this compound were set min. In accord- (5) CE; ance with one embodiment of the presentinven- N- -n an zcid ig-1 ml t r wmo ii 6 wflmhmh" may be coupled with a suitable thiazole radical to produce antineuritic compounds. The descrip- (6) cmcH,-Br tion contained in these prior applications will be .given herein for the sake of completeness. However since the group 2-methyl-6-axn1no-pryimcthyi-bromide-hydrobromide N --C-, The steps in the following detailed disclosure i correspond to the numbers in the above schedule. t! IL Step 1.-A mixture of 116 ms. of sulphuric acid (sp. g. 1.84), 18 gms. of water, 200 cc. absolute alcohol, and 99 ms. of p-ethoxy propionitrile is heated, under refluxing, for about six methyl-fi-oxy-pyrimethyl-ethyl'ether will first be given and this will be followed by specific examples of processes embodying the. invention in which various pyrimethyl esters are obtained from this compound and are condensed or coupled with a th'iazole compound to produce salts of vitamin 131 and related compounds having the antineuritic properties thereof.

Example I p A suitable pyrimethyl ester'for use in the coupling reaction is 2-methyl-6-amino-pyrlmethyl bromide and one process for making this bromide ester comprises a series of steps including those set forth in the-aforementioned copending applications which are substantially as follows: 1. p-Ethoxy-propionic-ethyi ester 2. Sodio-formyl-p-ethoxy-propionic-ethyl ester 3. z-methyl-u-oxy-pyrimethyl-ethyl'ether 4-. z-methyl-fi-chlor-pyrimethyl-ethyl ether with a thiazole compound to form an antin'euriti compound l The sequence and significance of these steps Sodio-iormyl-dethoxy-propionic-ethyl ester 5. 2-methyl-6-amino-pyrimethyl-ethyl ether 6. 2-methyl-6-amino-pyrimethyl-bromide '1. Coupling of hydrobromide of the bromide ester hours. At the end of this time, the mixture is cooled and allowed to stand until allthe ammonium bisulphate produced has crystallized out. The ammonium bisulphate is filtered off, washed several times with absolute a'ilcohol, and the combined filtrate and washings distilled to remove the major portion of alcohol. Ice water is added to the residue, the excess acid neutralized, and

the solution finally made slightly basic b the addition of sodium carbona e. The mixture is then extracted with ether, t e'ethereal solution dried-over sodium sulphate, and the solution fractiona'oed by distillation. -ethoxy propionicethyil-ester is obtained in the form of a pleasant is evolved, and a yellow salt precipitates out of the ether. If the reaction proceeds slowly, without causing ebullition of the ether, the amount of sodium specified is suflicient. However, if the reaction proceeds violently, increasing amounts of sodium up to a total of two equivalents may be necessary. For best results, the time for addition of the ester is about eight hours. The thus formed sodio-formyl derivative is used within isolation in the succeeding reaction. It must be protected from atmospheric moisture and should be used promptly, as it is not very stable.

Instead of the above described derivative, compoimds having-the general formula:

I i Y coon v wherein R and R are alkyl or aralkyl radicals and His an alkali metal, may be produced from appropriatereagents, if desired; by a similar method a'nd'used in the succeeding step.

Step 3.-To the ether suspension of the sodio-' Inthis formyl derivative obtained in Step 2, 45 gm. of acetamidine hydrochloride, 100 cc. of absolute alcohol, and a solution of 12-gms. of sodium in 200 cc. of absolute alcohol are added. The ether is distilled off, and the mixture heated, under refiuxing, for about sixteen hours. The contents of the flask are then cooled, neutralized with acetic acid, andevaporated down on a steam bath. The residue is taken up in a small amount of water and extracted repeatedly with chloroform. The combined choloform extracts are dried with sodium sulphate and the chloroform removed by evaporation. The remaining brown, gummy substance is treated with dioxane, after which a portion dissolves and a considerable quantity of the gum is solidified. The solid is dried and sublimed in high vacuo at 140 C. The sublimate is placed in a Soxhlet extractor and extracted repeatedly with anhydrous ether. The residue is dried and again subliined in high vacuo, yielding substantially pure Z-methyl-fi-oxy-pyrimethyl-ethyl ether having a melting point of about 175 to 176 C.

Instead of proceeding as above set forth the following preferred method of carrying out Step 3 may be employed:

To the reaction mixture obtained in Step 2,

add carefully a mixture of 100 to 200 gms. of

oXy-pyrimethyl-ethyl ether, is dried to constant may be produced, wherein R and R are allryl or aralkyl groups, by condensing compounds having the general formula indicated at the end of Step 2 with homologues of acetamidine, e. g.

propamidine, butamidine, etc.

Step 4.One gm. of 2-methyl-6-ox -pyrirnethyl-ethyl ether is heated with 8 cc. oi phosphorous oxychloride for about three hours at 78 C. The phosphorous oxyclrloride is then removed. in vacuo. The residue is poured onto ice and excess acid is neutralized by the addition of sodium bicarbonate or ammonia and the mixture extracted repeatedly with choloroform. The combined chloroform extracts are dried over sodium sulphate and the chloroform removed in vacuo. Approximately 1 gm. of an oily residue remains consisting largely of 2-methyl-6-chlor-pyrimethylethyl ether.

By employing compounds having the general formula til wherein R and R are alkyl or aralkyl radicals, compounds having the general formula N=CCl n -b i i-011 01;

l CH

are obtained.

Instead of the fi-chlor pyrimethyl compounds just described, the corresponding-fi-brom and 6- iodo compounds, which may be made in an analogous manner, may also be used if desired.

Step 5.The product of Step 4 is treated with about 5 to 15 cc. of alcoholic ammonia in a bomb tube at about 140 C. fora period of time sufficientto convert all bromine into ionic form e. g. three hours. The contents of the tube are then evaporated down, leaving a partly crystalline residue. This residue is dissolved in water, sodium bicarbonate or sodium carbonate is added and the solution extracted repeatedly with chloroform. The combined chloroform extracts are dried over sodium sulphate and the chloro= form removed in vacuo, leaving an oily residue which crystallizes on standing and cooling. The crude product may be recrystallized from ether or ligroin, and pure Z-methyl-G-amino-pyrimethyl-ethyl ether, having a melting point of 89.5 to 90.5" C. is obtained. If desired, the crude product may be purified by repeatedly subliming it in high vacuo at 60 to C.

Byemploying compounds having the general formula N=COl L -or ea NCH compounds having the formula may be obtained, wherein R and R are alkyl or arallzyl radicals.

Step 6.The 2-methy1-6-amino-pyrimethylethyl ether produced in accordance with the process outlined in Step 5 may be treated in various Ways to produce a hydrobromide of Q-methyl-fi-amino-pyrimethyl bromide. in one process 50 mgms. of 2-methyl-6-amino-pyrimethyl-ethyl ether are heated with 2 cc. of 60% hydrobromic acid in a bomb tube for about two and one-half hours at C. The contents of the tube are then removed, and concentrated in vacuo.

When the solution reaches small volume, crystals will separate. One cc. of cold water is added and sodium bicarbonate is added to the clear solution. When the solution is neutral, a precipitate is formed. This precipitate is extracted with chloroform, the chloroform solution dried over anhydrous sodium sulphate and the chloroform finally removed in vacuo. The

yield consists of about 20 mgms. of crystals. which give a strongly positive test for bromine.

and excess hydrobromic acid are removed in vacuo, leaving an acid ester which is a 2-methyl B-amino-pyrimethyl-bromide hydrobromide.

Step 7.-'-In one processof practicing the coupling reaction .about five drops of synthetic 4-methyl-5-p-hydroxy-ethyl thiazole are added to the 2-methyl-6-amino-pyrimethyl-bromide hydrobromide residue produced in accordance with Step 6 and the mixture is heated at about 120-125 C. for several hours. The resulting dark, gummy reaction product when tested physiologically exhibits the characteristic antineuritic action of vitamin B1.

Example I! In this example, the procedure outlined in Steps 1 to 5, inclusive, of Example I are followed to produce 2-methyl-6-amino-pyrimethylethyl ether. This is then converted into a bromide hydrobromide as follows:

150 gms.- of 2-methyl-6-amino-pyrimethylethyl ether are heated with 7.75 liters of a 10% solution of hydrobromic acid in glacial acetic acid for two hours at 100 C. (This is a ratio of slightly more than 3-mols hydrobromic acid to one mole of the ether.) 7 At the end of this time, the liquid remaining is decanted from the crystals which separateout. The crystals are washed several times with anhydrous etherand then may be purified by dissolving in a small amount of methanol and reprecipitating by the addition of the ether. The pure compound thus obtained melts at 192-103 C. and is a hydrobromide of 2-methyl-6-amino-pyrimethyl-bromide. The pure compound is not as stable as the crude product containing. small amounts of free hydrobromic and glacial acetic acid, which -hydroxy-ethyl-thiazole and 200 cc. of butanol for ininutesat 120 C.- The pyrimethyl compound goes into solution and at the same time a precipitate settles out. The reaction mixture is diluted with 1 liter of boiling absolute ethyl alcohol and allowed to stand until no more mate- .rial settles out. The alcoholic mother liquors are removed by filtration and the precipitate washed several times with'small amounts of.

cold absolute ethyl alcohol. The product obtained melts at about 229 C. and consists of the crude. bromide hydrobromide of the vitamin.

mide of the natural vitamin. Its absorption in the ultra violet is also identical with that of the corresponding saltoi the vitamin from natural sources. The pure product appears to hold onehalf mole of water oi crystallization.

Anal. calcd. for CuHisONsSZHBI. $1120: C,

33.09; H, 4.51; N, 12.87; found: C, 33.18, 32.76; i

Vitamin B1 is usually obtained from natur sources as the chloride hydrochloride. If desired, the bromide hydrobromide of the vitamin obtained by practicing the methods of either Example I or Example II may be converted into the chloride hydrochloride and the latter isolated in substantially pure form by the following procedure:

a 150 gms. of one of the'condensation products obtained in Examples I and II are dissolved in 2250 cc. of hot methanol and shaken with silver chloride. It is best to use vs. 10% excess of the silver salt and to shake with several successive portions rather than to add all the silver salt at once. The reaction is over in one-half hour usually. The silver salts are allowed to settle out and are filtered ofi. The filtrate is treated with anhydrous ether whereby the chloride hydrochloride is precipitated out.

This synthetic chloride hydrochloride exhibits the same ultra violet absorptionas does the I chloride hydrochloride of the natural vitamin but has a lower melting point and is more soluble in alcoholic solvents. It can be crystallized in all'the ways that are applicable to the natural a vitamin salt if appropriate allowance is made for its greater solubilities. It will be referred to herein as the low melting chloride hydrochloride. Pure crystals melting at 232-234 C. can be obtained by dissolving the crude chloride. hydrochloride obtained as described above in methanol and precipitating it with ether, or by dissolving one gram of the crude product in one cc. of

' water, adding 9 cc. of boiling alcohol and. allow- The precipitate then is recrystallized by dissolving in hot methanol, adding anhydrous ether? to the hot solution until a permanent cloud appears and allowing to cool slowly. The condensation product thus obtained occurs as rosettes'of needles which melt at 219-220 C. whereas the vitamin bromide hydrobromide from natural sources melts at 227-229" C.

With doses of 6 .01! either the crude or the recrystallized product, cures of polyneuritis are '1 effected in rats on a vitamin B1 free diet; which cures endure for about three days, indicating an ing the vessel to stand in a freezing mixture to induce crystallization.

A sample of the pure natural vitamin saltextracted from rice polishings melted at 246 C. and a mixture of this with the above synthetic low melting chloride hydrochloride melted at 242-244 C. The synthetic low melting chloride hydrochloride, like the naturalvitamin chloride hydrochloride, appears to hold about one-half molecule of water under the usual conditions. It has also been found to possess the same antineuritic 5 potency as is exhibited by th echloride hyd'rochlorideof the natural vitam Anal. calcd. fOr C12HisON4S.2HCl. v 41.60; H, 5.53;;N; 16.8; found: C, 41.21j--=-41.30; H, 5.50, 5.48; N,""i'6.25, 16.26.

A method of obtaining the synthetic chloride hydrochloride from the bromide hydrobromide in a form having the same melting point as the vitamin chloride hydrochloride extracted from rice polishings is as follows:

150 gms. of the bromide hydrobromide'condensation product obtained as described in Example I or Example 11 are dissolved in 300 'cc.

of water or 50% aqueous methanol and shaken with 225 gms. of silver chloride at room tempera- .ture for about three to four hours or until the reaction is completed. The silver bromide and chloride are filtered of! and the filtrate is evaporated in vacuo to dryness.

. It has been found that special treatment is necessary to make certain that the final product activity equal to that of the bromide hydrobro quite free from silver. In order to accomplish this, the residue above mentioned is dissolved in 1500 cc. of water and treated with a small amount of active charcoal (followed by filtration) until no further opalescencecan be observed. The clear solution is evaporated in vacuo until incipient crystallization occurs, then treated with 10 volumes of hot, absolute. alcohol. The resulting product is then filtered and dried. The product obtained by this method melts at about 246-250 C. according to the speed of heating.

It has been found that the low melting chloride hydrochloride and bromide hydrobromide produced by the methods hereinabove described can be converted into the high melting products by recrystallizing them from isoprcpyl alcohol or by dissolving them in absolute methyl alcohol and then precipitating with absolute ethyl alcohol.

Thus, two chloride hydrochloride's and bromide hydrobromides are-obtained having the same antineuritic properties as those isolated from. natural sources. One form of each salt has a melting point identical with-that of the corresponding vitamin salt obtained from natural sources, while the other has a lower melting point. Either low or high melting salts can be obtained at will, by observing the directions above set forth.

It has been found that the antineuritic potency and ultra violet absorption of the bromide hydrobromide and those of the chloride hydrochloride are about the same, indicating that these properties do not depend upon the acid portions of the salt but upon the basic portion.

By coupling acid salts of pyrimethyl esters other than the above described bromide hydrobromide with a suitable thiazole, other salts of vitamin B1 having comparable antineuritic properties may be prepared. The preparation of acid salts of a number of Z-methyl-d-amino-pyrimethyl esters and the coupling thereot with a 'thiazole nucleus to produce antineuritic compounds will now be described.

Example HZ in accordance with this process, Z-methyl-tamlno-pyrimethyl-ethyl ether, obtained as described hereinbefore, is reacted p-toluene sulphonic acid and the resulting p-toluene sulphonic acid salt of 2-methyl-fi-amino-pyrimethyl-p-toluene sulphonate is condensed with i-methyl--;3-hydroxy-ethyl thiazole to produce a compound having the antineuritic activityv characteristic of vitamin B1. In practicing this process a mixture of 57 mgms. oi E-methyl-d-aminopyrimethyl-ethyl ether and 125 mgms. of p-toluene sulphonic acid is heated at l1il-l20 C. for

two hours. The mixture is then cooled, whereupon it solidifies. 50 mains. of 4-meth3rl-5-flhydroxy-ethyl thiazole are added and the resulting mixture is heated at 125 C. for fortyfive minutes. The completely clear solution which is formed is cooled, and the product obtained is dissolved in 5 cc. of water. The pH. is then adjusted to 5-6 by adding potassium bicarbonate, and the material is extracted with ether, the extracts bein discarded. The aqueous solution obtained contains the p-toluene sulphonic acid salt of vitamin B1 p-toluene' sulphonate and exhibits an abundance of antineuritic activity.

Example IV In this example benezene sulphonic acid is caused to react with 2-1nethyl-6-amino=-Py B; p-naphthalene sulphonate.

methyl-ethyl ether to produce the benzene sulphonic acid salt of 2 methyl-B-amino-pyrimethyl-benzene sulphonate. The latter compound is then caused to react with @methyl-B-p-hydroxyethyl thiazole to produce the benzene sulphonic acid salt of vitamin B1 benzene sulphonate. In carrying out this process a mixture of 75.1 mgms. of benzene sulphOnic acid with 26 mgms. of 2- methyl-6-amino-pyrimethyl-ethyl-ether is heated for two hours at 115 G. Then 22 mgms. of 4- methyl-S-fi-hydroxy-ethyl thiazole are added and Example V In practicing the process, a mixture of c-naphthalene sulphonic acid, 2-methyl-6-amino-pyrimethyl-ethyl ether and glacial acetic acid is heated and, the resulting product is treated with t-rnethyl-5-;8-hydroxy-ethyl thiazole to produce the fl-naphthalene sulphonic acid salt of vitamin The specific details of practicing this process consist in preparing a mixture of 62A mgms. of fl-naphthalene sulphonic acid, 16.? mgms. of 2-methy1-6-amin0- pyrimethyl-ethyl ether and 1 cc. of lacial acetic acid and heating it at 0. to? two hours. The mixture is then cooled and evaporated to dryness in vacuo. To the crystalline product thus obtained 14.5 mgms. of 4-methyl-5-B-hydroxyethyl thiazole are added and the mixture is heated at for one hour. The product after cooling is dissolved in 5 cc. of water, after which the pH is adjusted to equal 5-6 by adding potassium bicarbonate. The product is extracted with ether, the extracts bein discarded, and the aqueous solution obtained exhibits abundant antineuritic activity.

Example VI with 23 mgms. of Z-methyl-fi-amino-pyrimethylethyl ether in 1 cc. of glacial acetic acid for two hours at 116 C. This solution is evaporated to dryness in vacuo at 90 C. and a crystalline product results. hydroxy-ethyl thiazole are added to the product and the mixture is heated at 115 C. for one hour. Upon cooling, the product is dissolved in 5 cc. of water and a pH equal 5-6 is obtained by adding potassium bicarbonate.- The product is repeatedly extracted with ether and the extracts discarded. The aqueous solution obtained after ex traction exhibits abundant antineuritic activity.

Antineuritic compounds similar to those described in Example III, IV, V and VI may be obtained by substituting for the aryl sulphonic acids described therein suitable alkyl sulphonic acids, such as methyl sulphonic acid and its homologues. Persons skilled in the art may readily obtain the related alkyl sulphonates of the vita min by suitably modifying the processes described g g e aerated r I in these examples. The sulphonlc acid esters emthe lactic acid attached as the e-amma group and ployed comprise the formula: then condensed with 4-methyl-5-p-hydroxy-ethyl 4 thiazole. Or, theunsubstituted lactic acid salt N=C NH,RSOH ot the pyrimethyl lactate may be.- condensed with 5 the thiazole, if desired. The resulting products 3 also exhibit the physiological properties of vita- I H V minBi. v

wherein R. i an alkyl'or aryl radical of the type Ix l desmbed h By procedure substantially identical with that Example VII The hydrobromide of 2-methyl-6-aminopyrimethyl-bromide produced in accordance with either Example I or Example II given hereinabove is caused to react with silver acetate to produce the corresponding acid ester, in which the bro mide radical and hydrobromic acid of the pyrimethyl ester are replaced by the acetate radical and acetic acid, respectively. In carrying out this reaction .4 gins. oi the hydrobromide of the substituted pyrimethyl-bromide are mixed with 1.8 gms. of silver acetate, 5 cc. of glacial acetic acid are added and the resulting mixturei heated on a steam bath for about one hour with occasional stirring. The reaction mixture is then cooled and filtered. The complet redescribed in- Examples VII and VIII, 2-methyl-6- amino-pyrlmethyl-bromide hydrobromide is treated with silver benzoate. The benzoate ion in the resulting product may be replaced by the pan pyrimidine is shown by the fact that the filtrate to replace the acetic acid, added to the amino group in the 6 position, by hydrobromic acid (1 molecular equivalent) is added to the filtrate and an excess of ether is added to precipitate the resulting compound. The precipitate which is the hydrobromide of 2-methyl-6-amino-pyrimethyl-acetate, is filtered out of the solution and the filtrate i washed with ether. The precipitate is then dissolved in butyl alcohol and an equivalent quantity of the hydrobromide of 4- methyl-S-B-hydroxy-ethyl thia-zole is added to the solution which is then heated for one hour at about 115 C.v The butyl alcohol is removed from the reaction product by evaporation and the residue is dissolved in water, filtered and its pH adjusted to 6. Physiological assays of this product show decided antineuritic activity.

It is preferable to couple the hydrobromide of the pyrimethyl-acetat with the thiazole because the salts of vitamin B1 which have an acid reaction are the more stable ones and the presence'of hydrobromic acid is therefore desirable in place 01. the relatively weak acetic acid in order to obtain a more stable antineuritic salt. However, it is not essential to employ the hydrobromide of this ester and antineuritic compounds may be obtained by using the acetic acid salt or the pyrimethyl-acetate in the coupling reaction.

Emgmple VIII By'a reaction similar to that described under Example VII the lactic acid salt ,of 2-methyl-6- amino-pyrimethyl lactate may be employed to produce an acid salt of vitamin B1 having antineuritic properties. In this process 1.7 gms. of-2- methyl-S-amino-pyrimethyl-bromide hydrobromide are caused to react with 1.07 gms. of silver lactate to produc the corresponding pyrimethyl lactate.

Example VlI with hydrobromic acid to replace This may be treated as described in bromide ion and the resulting product condensed with the hydrobromide oi 4-methyl-5-fl-hydroxyethyl thiazole. In this reaction, 1.4 gms. or the bromide hydrobromide of the substituted pyrimidin are caused to react with 2.29 gms. 01' silver benzoate, and in the remaining steps of the process sufficient quantities of hydrobromic acid and of 4-methyl-5-B-hydroxy-ethyl thiazole, respectively, are employed to constitute molar equivalents. Also the unreplaced benzoic acid salt or the pyrimethyl benzoate may be utilized, if desired, in the coupling reaction. In either case, products having strong antineuritic action are obtained.

By methods analogous to the foregoing ones, the corresponding acid salts of the chloride, sulphate, phosphate and nitrate esters of the aforementioned pyrimethyl compound may be prepared and caused to condense with a suitable thiazole, for example, 4-methyl-5- B-hydroxyethyl thiazole, to produce compounds having antineuritic properties.

The antineuritic compounds described in the various examples given herein may be separated from their impurities and obtained in a substantially pure state by suitable adaptations of the method of isolation outlined in Example 11 hereof.

The fact that all of the compounds resulting from the coupling reactions described hereinabove exhibit antineuritic activity clearly demonstrated that this property is obtained in compounds havinga substituted pyrimethyl group coupled with a substituted thiazole group and which possess the following general formula:

N=C =C -t acm 1 ea lea in which X represents an acid radical which may be varied almost at will.

Although in all of the examples recited hereinabove, the pyrimethyl group has a methyl group located in the 2 position and an amino group in the 6 position and the thiamle group has a niethyl group in the 4 position and a p-hydroxy-ethyl group in th 5 position, the invention is not limited to these particularderivatives. For example, the methyl group in the 2 position 01' the pyrimethyl radical particularly described, but it is to be understood that the invention is not limited to the coupling with a thiazole 01' a pyrimethyl ester which has I been isolated as such before the coupling reaction is effected. The invention also contemplates the utilization of a pyrimethyl alcohol, ether or ester in the presence of an acid in a coupling reaction whereby the pyrimethyl group and the anion portion of the acid add directly to the nitrogen of the thiazole to produce a quaternary thiazole compound. These compounds are all examples of reactive pyrimethyl compounds as that term is employed herein.-

In most of the above described coupling or condensing reactions, a basic thiazole, such as methyl--B-hydroxy-ethyl thiazole, has been specifically mentioned. However, these reactions will also proceed satisfactorily if salts or the thiazole are employed insmad of the free base. Thus, for example, the hydroloromideof 4-methy1- 5- 8-hydroxy-ethy1 thiazole may be coupled with the hydrobromide of Z-methyl-d-amino-pyrimethyl-bromide to produce the hydrobromide of vitamin B1. Hence, whenever the term thiazole" is used in the annexed claims, it is intended to mean either the free base or a salt of the thiazole.

Also, in general, where G-amino-pyrimethyl and other amino compounds are mentioned, the acid salts thereof formed by the addition of acids to the basic amino groups are also contemplated. Consequently, the formulae given herein and in the annexed claims for the basic amino com pounds are intended to comprise the salts. For convenience of operation-it is sometimes more advantageous to use the free base and at other times better to employ a salt thereof. The particular compound employed will of course be chosen to fit the requirements of'the reaction involved.

- Where alkyl groups are described as substituents in the various compounds mentioned herein, aralkyl groups may in general be used with satisfactory results. Hence, when the term alkyl is used herein and in the annexed claims, it is also intended to embrace the aralkyl roups.

What is claimed is:

1. The process which comprises reacting a 2- alkyl-6-amino-pyrimethyl ester with -methyl- 5-c-hydroxy-ethyLthiazole.

2. The process of producing antineuritic compounds which comprises reacting'a 2l-methlv fi-amino-pyrimethy] ester with 42-methyl-5fi-hy= droXy-ethyl thiazole.

3. The process which comprises reacting 4- methyl-S-p-hydroxy-ethyl thiazole with a reac= tive 2 alkyl 6 amino-pyrimethyl compound which forms a quaternary antineuritic com round with the trivalent nitrogen atom of the thiazole.

4. The process of producing compound havin antineuritic properties which comprises condensing 2-methyl-6-amino-pyrimethyl-acetate with 4-methyl- -;3-hydroxy-ethyl thiazole.

5. The process of producing compounds having antineuritic properties which comprises coupling a 2-rnethyl-G-amino-pyrimethyl ester, in which the acid radical or element is a member or" the group consisting of the halogen, acetate, lactate, benzoate, nitrate, phosphate and sulphate radicals, with 4-methyl-5-3-hydroxy-ethyl thiazole.

6. The process which comprises treating a re active pyrimethyl compound of the group consisting of 2-methyl-6-amino-pyrimethyl alcohol, ethers and esters with -methyl-fi-fi-hydroxw ethyl thia zole in the presence of an acid.

'7. The process of producing antineuritic com! bit compo e of "we pounds which comprises reacting an ester of the group having the formulae N=C-NEE1 5 CHr'-C% rc-c-E and rr=c miam ll i i-G-E N: c range a rc-c-z in winch 5E Z are 251% consisting of the acet ate, nitrate, phospand snlr with -methgl-E 9. An antlne sisting of the camp ..r the gr cup An ant commen iof the consisting oi t e lac:

the presence e2": 5 rmei' r d-amiuo-pm'im a thiazo-ie having the i re i fo=cgz-crr cri z in which R is an alkyl group and Z is a member of the group consisting of OH and groups and elements readily convertible into H.

12. The process which comprises reacting a substituted thiazole having the formula in which R is an alkyl group and Z is a. member of the group consisting of OH and groups and. elements readily convertible into OH, with a reactive 2-allryl-6-amino-pyrimethyl compound which forms a quaternary compound with the trivalent nitrogen atom of the thiazole.

13. The process which comprises reacting a substituted thiazole having the formula in which R is an alkyl group and Z is a member of the group consisting of OH and groups and elements readily convertible into OH, with a reactive 2-alkyl-6-amino-pyrimethyl ester.

14. The process which comprises treating a reactive pyrimethyl compound of the group consisting of 2-alkyl-6-amino-pyrimethyl alcohol, ethers and esters with 4-methyl-5-p-hydroxy-ethyl thiazole in the presence of an acid.

15. The reaction product obtained by reacting a hydrobroinide of Z-rnethyI-G-amino-pyrimethylbromide with 4-methyl-5-p-hydroxy-ethyl-thiazole, said product having the characteristic physiological properties of vitamin B1.

16. A process for the preparation of vitamin B1 hydrohalide which comprises converting fiethoxy-propionic-ethyl ester to its corresponding sodioformyl derivative, condensing the latter with acetamidine' to form 2-methyl-6-oxypyrimethyl-ethyl ether, converting this last-named product into 2-methyl-6-halo-pyrimethyl-ethylether, converting this into 2-methyl-6-amincpyrimethyl-ethyl-ether, converting the latter product into z-methyl-fi-amino-pyrimethyl halide, and finally, condensing the latter product with 4-methy1-S-p-hydroxy-ethyl-thiazole lay-- having the physiological properties of vitamin Ba ethyl thiazole.

l9. An antineuritic compound of the structure:

N=CNHz.HBr' =CH2CH2OH CHa CH2 N -CH r (J-S having a melting point of 219 to 220 C.

20. The process for the production of an antineuritic compound which comprises the condensation of a hydrobromide of 2-methyl-6-aminopyrimethyl-bromide with 4-methy1-5-fl-hydroxyethyl thiazole in the presence of butanol at a temperature of about C.

21. The process for the production of an antineuritic compound which comprises the condensation of a hydrobromide of 2-methyl-6-aminopyrimethyl-bromide with 4-methy1-5-B-hydroxyethyl thiazole in the presence of butanol.

22. The process of making antineuritic compounds which comprises condensing 4-methyl-5- ,o-hydroxy-ethyl thiazole with a compound having the formula IN=AC -NH;.HX1 R- oE -x NCH in which X and X are acid radicals at least one of which is bromine and R is an alkyl group.

23. The process of making antineuritic compounds which comprises condensing 4-methyl-5- p-hydroxy-ethyl thiazole with a. compound havin which X and X are acid radicals at least one of which is bromine.

24. An antineiu'itic compound having the in which X and X are acid radicals and at least one of which is bromine.

25. An antineuritic compound of the structure:

'26. The process for converting a bromide hydrobromide' compound such as is shown in claim 25 into its corresponding chloride hydrochloride which comprises reacting upon the former with silver chloride.

27. The process which comprises reacting upon '4-methyl-5-p-hydroxy-ethyl-thiazole with a 2- methyl-S-aminopyrimidyl-halide.

28. The process which comprises reacting upon a 4-alky1-5-p-hydroxy-ethyl-thiazole with a reactive 6-amino-pyrimidyl-5-lower-alkyl ester.

29. The process which comprises reacting upon a 4-alkyl-fi-p-hydroxy-ethyl-thiazole with a 6- amino-pyrimidyl-5-lower-alkyl-bromide.

31. The process which comprises reacting upon a 4-a11qrl-5-hydroxy-alky1 thiazole with a. 2- alkyl-G-amino-pyrimidyl-E-lower alkyi halide,

32. The process which comprises reacting upon -methyl-E- 6-hydroxvethy1-thiazo1e with a 2= lower alkyl-S-amino-pyrimcthyl-halide.

33. The process which comprises meeting rm der acid conditions a. reactive z-lower-alkyl c amino-pyrimethsi ester with i-methy1-5-fi-hy= droxy-ethyl ihiazole.

34-. The process which comprises reacting um- I ester.

der cold conditions a. reactive 2-methyi-6-amino pyrimethyl ester with -methyl-En-p-hydroxjethyl thiazcle.

35. The process which comprises condensing a,

hydrobromide of Z-methyl-fi-amino-pyrimethylbromicic with -meth'yl-S-B-hydroxy-ethyl thiafi An antineuritic compound of the structurez' CH: N=CNE;.CHC6OH a J=comomo11 CHtr-( Hg 7 ROBERT E. WILLIAMS. JOSEPH K. CHINE.