NO148453B - ANALOGY PROCEDURE FOR THE PREPARATION OF THERAPEUTIC ACTIVE SPIROHYDANTOIN DERIVATIVES - Google Patents

Description

This invention relates to a method for the production of new pharmacologically active hydantoin derivatives.

More specifically, the invention relates to the preparation of a new series of spiro-hydantoin compounds which are particularly useful because of their ability to counteract certain chronic complications arising due to diabetes mellitus (e.g. diabetic cataract and neuropathy).

Numerous attempts have previously been made by many researchers to find new and better oral antidiabetic agents.

These attempts have mainly included synthesis and investigation

of hitherto new and unknown organic compounds, particularly sulfonylurea derivatives, to determine their ability to significantly lower blood sugar levels (i.e. glucose) when administered orally. In the search for new and more effective antidiabetic agents, however, little has been done to find out the effect of other organic compounds in preventing or reducing certain chronic complications arising from diabetes, such as diabetic cataract, neuropathy, retinopathy, etc. I However, US patent 3,281,383 states that certain aldose reductase inhibitors such as 1,3-dioxo-1H-benz[d,e]-isoquinoline-2(3H)-acetic acid and some closely related derivatives thereof are useful for this purpose, although these particular compounds are not known to be hypoglycemic in nature.

These particular aldose reductase inhibitors all work by

they inhibit the activity of the enzyme aldose reductase, which is particularly responsible for regulating the reduction of aldoses (such as glucose and galactose) to the corresponding polyols (such as sorbitol and galactitol) in the human body. In this way, unwanted accumulations of galactitol in the lens of galactosemic individuals and of sorbitol in the lens, peripheral nerve cord and kidney of various diabetic individuals can be prevented or otherwise reduced. As a result, these compounds are undoubtedly valuable as aldose reductase inhibitors for the regulation of certain chronic diabetic complications, including those of an ocular nature, since it is known

that the presence of polyols in the lens of the eye inevitably leads to cataract formation together with an accompanying loss of lens clarity.

It has now surprisingly been found that various spiro-hydantoin compounds are very useful when used in therapy as aldose reductase inhibitors to combat certain chronic diabetic complications in humans to whom they are administered.

The new compounds produced according to the invention have the formula:

and the base salts thereof with pharmacologically acceptable cations, where A is where X is hydrogen and X <2> is fluorine, hydroxy or 6'-(lower alkoxy); or X and X <2> are each lower alkoxy or are together 3 4 -OCH2(CH2) 0- where n is 0 or 1; X is hydrogen and X is 7'-(lower alkoxy); or X and X 1 are each lower alkoxy; X 5 is hydrogen, and X <6> is fluorine, chlorine, bromine or lower alkoxy; 5 6 7 or X and X are each chloro or lower alkoxy; X is hydrogen and X Q is hydrogen or fluorine, Y is oxygen or sulfur; and

provided that X^ and X^ are alkyl only if

Y is oxygen, and X is hydrogen, and X begs chlorine or bromine only if Y is sulfur.

Of particular interest in this context are such typical and preferred compounds as 6-fluoro-spiro-[chromane-4,41-imidazolidine]-2<1>,5'-dione, 6,7-dichloro-spiro-[chromane- 4,4<1->imida-zolidin]-2',5'-dione and 6',7'-dichloro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione. These particular compounds are all very potent in their aldose reductase inhibitory activity, as well as being very effective in significantly lowering sorbitol levels in the sciatic nerve and lens of diabetic individuals and galactitol levels in the lens of galactosemic individuals.

According to the present invention is produced

the new compounds of formula I in that a suitable carbonyl ring compound of formula A where A is as indicated above,

0

such as the corresponding 1-indanone, 1-tetralone, 4-crcmanone, thiochroman-4-one and thioindan-3-one-1,1-dioxide with the formulas:

where X, X<2>, X<3>, X<4>, X<5>, X<6>, X<7>, X<8>, Y and Q are all as stated above, is traded with a alkali metal cyanide (eg sodium cyanide or potassium cyanide) and ammonium carbonate to form the desired spiro-hydantoin end product of the above formulas. This reaction is normally carried out in the presence of a reaction-inert, polar organic solvent medium where both the reaction components and the reagents are mutually miscible. Preferred organic solvents for use in this context include cyclic ethers such as dioxane and tetrahydrofuran, lower alkylene glycols such as ethylene glycol and trimethylene glycol, water-miscible lower alkanols such as methanol, ethanol and isopropanol, as well as N,N-di(lower alkyl)-lower alkanoylamides such as N,N-dimethylformamide, N,N-diethylformamide and N,N-dimethylacetamide, etc. In general, the reaction is carried out at a temperature in the range from approx. 20°C up to approx. 120°C for a period of approx. 2 hours to approx. 4 days. Although the amount of reaction components and reagents used in the reaction may vary to a certain extent, it is preferred to use at least a slight molar excess of the alkali metal cyanide reagent relative to the carbonyl ring compound starting material in order to obtain maximum yield. On completion of the turnover, the desired product is easily isolated in the usual way, e.g. by first diluting the reaction mixture with water (optionally by boiling) and then cooling the resulting aqueous solution to room temperature, followed by acidification to obtain the desired spiro-hydantoin compound in the form of an easily recoverable precipitate.

Compounds where A- has formula VIII can optionally be prepared from the corresponding compounds where A has formula VII where Y is sulfur by simply oxidizing the latter group of compounds according to standard methods well known to those skilled in the art. Application of e.g. sodium periodate in this context leads to the formation of the oxo-sulfur compounds, while peroxy acids such as petacetic acid, perbenzoic acid and m-chloroperoxybenzoic acid, etc., are preferably used to obtain the corresponding dioxosulfur compounds. The new compounds where A has formula V where X<2 >is hydroxy are usually preferably prepared by first preparing the corresponding alkoxy compound where X 2 is lower alkoxy, after which the latter is converted into the desired hydroxy compound by splitting off the ether group in the usual way.

The starting materials required for the production of the new spiro-hydantoin compounds are largely known compounds and are either easily commercially available,

such as 1-indanone and 6-chloro-4-chromanone, etc., or they can be easily synthesized by those skilled in the art by starting from common chemical reagents and using common methods of organic synthesis.

E.g. 6-fluoro-4-chromanone is prepared by condensing 3-(p-fluoro-phenoxy)propionic acid in the presence of polyphosphoric acid, while 6,7-dichloro-thiochroman-4-one is prepared by condensing 3-(3,4-dichloropheny1 -thio)-propionic acid in the presence of concentrated sulfuric acid. In both cases, the starting organic acid is derived from a commercially available compound.

The chemical bases used as reagents in the method according to the invention for the production of the above-mentioned pharmaceutically acceptable base salts are those which form non-toxic salts with the various acidic spiro-hydantoin compounds, such as e.g. 6-Fluoro-spiro-[chromane-4,4'-imidazolidine]-2<1>,5<1->dione. These non-toxic base salts are of such a nature that their cations can be considered to be approximately non-toxic over the wide dosage range used. Examples of such cations include sodium, potassium, calcium and magnesium, etc. These salts can be easily prepared by simply processing

the above spiro-hydantoin compounds with an aqueous solution of the desired pharmacologically acceptable cation, and then evaporating the resulting solution to dryness, preferably under reduced pressure. Alternatively, they can also be prepared by mixing together lower alkanol solutions of the acidic compounds and the desired alkali metal alkoxide and then evaporating the resulting solution to dryness in the same manner as before. In any case, stoichiometric amounts of the reagents must be used to achieve complete conversion and maximum yield formation of the desired end product.

As indicated above, the new spiro-hydantoin compounds are suitable for therapeutic use as aldose reductase inhibitors for combating chronic diabetic complications, due to their ability to reduce the amount of sorbitol in lenses of diabetic subjects to a statistically significant degree. 6-Fluoro-spiro-[chromane-4,41-imidazolidine]-25'-dione, which is a typical and preferred compound, is e.g. found to

persistently control (ie inhibit) the formation of elevated

sorbitol amounts in diabetic rats to a significantly high degree by oral administration in doses from 0.75 to 20 mg/kg, without showing signs of any toxic side effects. The other compounds prepared according to the invention also cause similar results. All of the compounds described herein can be administered either orally or parenterally, for the desired purpose, without causing significant unwanted pharmacological side effects in the individual to whom they are administered. Generally, the compounds are administered in amounts from approx. 0.1 to approx. 10 mg/kg body weight per day, although variations will necessarily occur depending on the weight and condition of the individual being treated, and the particular form of administration chosen.

The activity of the new compounds as means of combating chronic diabetic complications is determined by their ability to satisfy one or more of the; following standard biological and/or pharmacological tests, namely (1) measuring their ability to inhibit the enzyme activity of isolated aldose reductase; (2) measuring their ability to reduce or inhibit sorbitol accumulation in the sciatic nerve in acutely streptozotocinated (ie, diabetic) rats; (3) measurement of their ability to drive back already elevated sorbitol levels in the sciatic nerve and lens of chronic streptozotocin-induced diabetic rats; (4) measuring their ability to prevent or inhibit galactitol formation in the lens of acute galactosemic rats, and (5) measuring their ability to delay cataract formation and reduce the degree of lens opacity in chronic galactosemic rats.

Preparation A

A mixture consisting of 3.5 g (0.019 mol) of 3-(p-fluoro-phenoxy)-propionic acid (Finger et al., Journal of the American Chemical Society, vol. 81, p. 94 (1959)) and 40 g of polyphosphoric acid was heated on a steam bath for a period of 10 minutes and then poured into 300 ml of ice water. The resulting aqueous solution was then extracted with three separate portions of ethyl acetate, and the combined organic layers were then washed with dilute aqueous sodium bicarbonate solution and then with water, followed by drying over anhydrous magnesium sulfate. After removal of the drying agent by filtration and the solvent by evaporation under reduced pressure, a residue was finally obtained which was then recrystallized from ethanol to give 2.93 g (93%)

pure 6-fluoro-4-chromanone, m.p. 114-116°C.

Analysis: Calculated for C9H7F02-0.25 H2O: C 63.34, H 4.43

Found: C 63.24, H 4.15.

Production B

To a solution of 12.5 g (0.07 mol) of 3,4-dichlorobenzenethiol (available from Aldrich Chemical Company, Inc., Milwaukee, Wis.) in 35 mL of 2N aqueous sodium hydroxide and

5 ml of ethanol, an ice-cold solution consisting of 7.6 g (0.07 mol) of β-chloropropionic acid (also available from Aldrich) was added

and 8.6 g (0.07 mol) of sodium carbonate monohydrate dissolved in 50 ml of water. The resulting reaction mixture was then heated on a steam bath for a period of 2 hours, cooled to room temperature (about 25°C) and extracted with ethyl acetate to remove any impurities. The collected aqueous portion was then poured into 300 ml of ice-cold 3N hydrochloric acid, and the thus precipitated solids were then collected by suction filtration. After washing the latter material with water, air-drying to constant weight and recrystallization from ethyl acetate/n-hexane, a yield of 11.4 g (65%) of 3-(3,4-dichlorophenylthio)-propionic acid was obtained, sm .p. 70-72°C.

Analysis: Calculated for CgHgCl2S: C 43.04, H 3.21.

Found: C 43.13, H 3.25.

A solution of the above product in concentrated sulfuric acid was prepared by placing 5.0 g (0.02 mol)

(3-(3,4-dichlorophenylthio)propionic acid to 50 ml of ice-cold concentrated sulfuric acid with constant stirring during the addition. The resulting solution was then stirred at 0°C for a period of 20 minutes and finally at room temperature for

another 20 minutes. At this point, the entire reaction mixture was poured into 300 mL of an ice-water mixture, and the precipitated solids were collected by suction filtration, washed with water, and air-dried to constant weight. Recrystallization from ethanol then gave 2.5 g (54%) of pure 6,7-dichlorothiochroman-4-one,

sm.p. 134-136°C.

Analysis: Calculated for CgHgC^OS: C 46, 37, H 2.60

Found: C 46.34, H 2.45.

Example I

A mixture consisting of 2.5 g (0.15 mol) of 6-methoxy-1-indanone (available from Aldrich Chemical Company, Inc., Milwaukee, Wis.), 1.5 g (0.23 mol) of potassium cyanide and 6, 7 g (0.07 mol) of ammonium carbonate in 20 ml of ethanol was placed in a stainless steel bomb and heated at 110°C for 20 hours. After cooling to room temperature (approx. 25°C), the contents of the bomb were diluted with 100 ml of water and then acidified to pH 2.0 with 6N hydrochloric acid. The precipitate thus obtained was then collected by suction filtration and was then recrystallized from ethanol to give 0.49 g (14%) of pure 6<1->methoxy-spiro-[imidazolidin-4,1'-indane]-2,5 -dione, sm.p. 192-194°C.

Analysis: Calculated for <c>12<H>i2<N>2°3<:> C 62'06' H 5'21' N 12.06.

Found: C 61.94, H 5.26, N 12.01.

Example II

The procedure described in Example I was repeated, except that 6-fluoro-l-indanone (Chemical Abstracts, vol. 55, p. 25873a (1961)) was the starting material used instead of 6-methoxy-l-indanone, using the same mole parts as before. In this particular case, the corresponding final product obtained was 6'-fluoro-spiro-[imidazolidin-4,11-indane]-2,5-dione, m.p. 255-257°C. The yield of pure product was 4.6% of the theoretical value.

Analysis: Calculated for c1iHi9FN2O2: C 60'00' H 4»12, N 12.72

Found: C 59.86, H 4.33, N 12.49

Example in

The procedure described in Example II was repeated, except that 5,6-dimethoxy-1-indanone (Koo, Journal of the American Chemical Society, vol. 75, p. 1891 (1953)) was used as starting material instead of 6-methoxy- l-indanone, using the same mold parts as before. In this case the corresponding final product was 5<1>,6'-dimethoxy-spiro-[imidazolidin-4,1'-indane]-2,5-dione, m.p. 246-248°C. The yield of pure product was 48% of the theoretical value.

Analysis: Calculated for C13<H>14<N>2°4<:> c 59'53' H 5.38, N 10.68.

Found: C 59.26, H 5.49, N 10.54.

Example iv

The procedure described in Example I was repeated, except that 5,6-methylenedioxy-1-indanone (Perkin and Robinson, Journal of the Chemical Society, vol. 91, p. 1084 (1907)) was used as starting material instead of 6-methoxy -l-indanone, using the same mold parts as before. In this case, the corresponding end product was 5',6'-methylenedioxy-spiro-[imidazolidin-4,11-indane]-2,5-dione, m.p. 248-250°C. The yield of pure product was 29% of the theoretical value. Analysis: Calculated for C12H10<N>2°4: C 58'53' H 4'09' N H»38

Found: C 58.44, H 4.14, N 11.25.

Example V

The procedure described in Example I was repeated except that 6-methoxythiochroman-4-one (Chemical Abstracts,

Vol. 53, p. 7161c (1959)) was used as starting material instead of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 6'-methoxy-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione, m.p. 170-172°C. The yield of pure product was 41% of the theoretical value.

Analysis: Calculated for C12<H>12<N>2°3<S:> C 54'53' H 4'58' N 10»61

Found: C 54.64, H 4.67, N 10.66.

Example VI

The procedure described in Example I was repeated, except that 6-chlorothiochroman-4-one (Chemical Abstracts,

Vol. 55, p. 12397c (1961)) was used as starting material instead of 6-methoxy-1-indanone, using the same mole fractions as before. In this particular case, the corresponding final product obtained was 6'-chloro-spiro-[imidazolidin-4,4'-thiochroman]-2,5-dione, m.p. 244-246°C. The yield of pure product was 53% of the theoretical value. Analysis: Calculated for C^HgClN^S: C 49.16, H 3.38, N 10.43

Found: C 49.23, H 3.40, N 10.39.

Example VII

The procedure described in Example I was repeated, except that 6-bromothiochroman-4-one (Arndt, Chemische Berichte, vol. 58, p. 1612 (1925)) was used as starting material instead of 6-methoxy-1-indanone, using of the same mold parts as before. In this case, the corresponding final product obtained was 6<1->bromo-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione, m.p. 234-236°C. The yield of pure product was 56% of the theoretical.

Analysis: Calculated for C-^HgBrN^S: C 42.18, H 2.90, N 8.95.

Found: C 41.98, H 2.92, N 8.95.

Example VIII

The procedure described in Example I was repeated, except that 6,7-dichlorothiochroman-4-one (prepared as described under Preparation A) was used as starting material instead of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 6<1>,7'-dichloro-spiro-[imidazolidine-4,4<1->thiochroman]-2,5-dione, m.p. 298-300°C. The yield of pure product was 49%

of the theoretical.

Analysis: Calculated for C^HgC^N^S: C 43.58, H 2.66, N 9.24.

Found: C 43.77, H 2.85, N 9.38.

Example IX

The procedure described in Example I was repeated, except that 6-fluorothiochroman-4-one (Chemical Abstracts,

Vol. 70, p. 47335x (1969)) was used as starting material instead of 6-methoxy-1-indanone, using the same mole fractions as before. In this case, the corresponding final product obtained was 6'-fluoro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione, m.p. 200-202°C. The yield of pure product was 60% of the theoretical.

Analysis: Calculated for C^HgFN^S: C 52 , 37, H 3.60, N 11.11

Found: C 52.36, H 3.73, N 11.05.

Example X

The procedure described in Example I was repeated, except that 8-chlorothiochroman-4-one (Chemical Abstracts, vol. 53, p. 7161c (1959)) was used as starting material instead of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 8'-chloro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione, m.p. 265-267°C. The yield of pure product was 66% of

the theoretical.

Analysis: Calculated for C^HgClN^S: C 49.16, H 3.38, N 10.43

Found: C 49.32, H 3.50, N 10.38

Example XI

The procedure described in Example I was repeated, except that 7-chlorothiochroman-4-one (Chemical Abstracts, vol. 52, p. 11044b (1958)) was used as starting material instead of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 7<1->chloro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione, m.p. 235-237°C. The yield of pure product was 67% of the theoretical.

Analysis: Calculated for Ci;LHgClN 2 O 3 S: C 49.16, H 3.38, N 10.43.

Found: C 49.32, H 3.36, N 10.03.

Example XII

The procedure described in Example I was repeated, except that 7-methoxy-1-tetralone (available from Aldrich Chemical Company, Inc., Milwaukee, Wis.) was used as starting material in place of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 3',4<1->dihydro-7<1->methoxy-spiro-[imidazolidine-4,1<1>(2<1>H)naphthalene]-2 ,5-dione, m.p. 227-229°C. The yield of pure product was 59% of the theoretical. Analysis: Calculated for ci3Hi4<N>2°3<:> c 63'40' H 5.73, N 11.38

Found: C 63.19, H 5.68, N 11.30.

Example XIII

The procedure described in Example I was repeated, except that 6,7-dimethoxytetralone (Howell and Taylor, Journal of the Chemical Society, p. 1248 (1958)) was used as starting material instead of 6-methoxy-1-indanone, using the same mold parts as before. In this case, the corresponding final product obtained was 3',4<1->dihydro-6',7<1->dimethoxy-spiro-[imidazolidine-4,1<1>(2H)-naphthalene]-2 ,5-dione, m.p. 238-240°C. The yield of pure product was 49% of the theoretical. Analysis: Calculated for <C>14H16N2°4: c 60.86, H 5.84, N 10.14

Found: C 60.94, H 6.04, N 10.48.

Example XIV

A solution of 1.18 g (0.005 mol) of 6<1->methoxy-spiro-[imidazolidin-4,1'-indan]-2,5-dione (prepared as described in Example I) in 10 ml of methylene chloride was cooled to -65°C, and to this solution was then added dropwise a solution consisting of 1.44 ml (0.015 mol) of boron tribromide dissolved in 10 ml of methylene chloride, while the entire reaction mixture was stirred under a nitrogen atmosphere. The resulting mixture was then allowed to reach room temperature (about 25°C) by removing the cooling bath, and was then held at this temperature for 7 hours. After this, 30 ml of water was added dropwise to the mixture, and the separated organic layer was then collected and dried over anhydrous magnesium sulfate. After removal of the organic solvent (ie, methylene chloride) by evaporation under reduced pressure, a residual material was obtained which was then recrystallized from ethanol to give 240 mg (22%) of pure 6'-hydroxy-spiro-[imidazolidine -4,1'-indan]-2,5-dione, m.p. 253-255°C.

Analysis: Calculated for C11H10<N>2<0>3<:> c 60.54, H 4.62, N 12.84

Found: C 60.29, H 4.66, N 12.93.

Example XV

A mixture consisting of 6.2 g (0.033 mol) 6-methoxy-4-chromanone (British Patent 1,024,645), 2.8 g (0.043 mol) potassium cyanide and 8.26 g (0.086 mol) powdered ammonium carbonate in 40 ml ethanol was placed in a stainless steel bomb and heated to 60°C in an oil bath for a period of 24 hours. The reaction mixture was then diluted with 300 ml of water, boiled for 15 minutes, and after being cooled to room temperature, acidified with 6N hydrochloric acid. The precipitated product thus obtained was then collected by suction filtration and then recrystallized from ethanol to give 6-methoxy-spiro-[chroman-4,4<1->imidazolidine]-2',5'-dione, m.p. . 170-172°C. The yield of pure product was 32% of the theoretical.

Analysis: Calculated for c12Hi2N2°4: C 58'06' H 4.87, N 11.29

Found: C 58.04, H 4.98, N 11.17.

Example XVI

The procedure described in Example XV was repeated, except that 6-fluoro-4-chromanone (prepared as described in Preparation B) was the starting material used instead of 6-methoxy-4-chromanone, using the same mold parts as above. The corresponding final product obtained was 6-fluoro-spiro-[chroman-4,4'-imidazolidine]-2',5<1->dione, m.p. 239-241°C. The yield of pure product was 36% of the theoretical. Analysis: Calculated for C HgFN 2 O 3 : C 55.93, H 3.84, N 11.86

Found: C 55.54, H 3.88, N 12.12

Example XVII

The procedure described in Example XV was repeated, except that 6,7-dichloro-4-chromanone (West German Off.skrift 1,928,027) was used as starting material instead of 6-methoxy-4-chromanone, using the same template parts as earlier. The corresponding final product obtained here was 6,7-dichloro-spiro-[chroman-4,4'-imidazolidine]-2',5'-dione, m.p. 263-265°C. The yield of pure product was 8% of the theoretical.

Analysis: Calculated for C1;LH8C12N203: C 46.02, H 2.81, N 9.76

Found: C 45.83, H 2.94, N 9.65.

Example XVIII

The procedure described in Example XV was repeated, except that 6,8-dichloro-4-chromanone (Huckle et al., Journal of Medicinal Chemistry, vol. 12, p. 277 (1969)) was used as starting material instead of 6-methoxy -4-chromanone, using the same mold parts as before. The corresponding final product obtained here was 6,8-dichloro-spiro-[chroman-4,4'-imidazolidine]-2',5'-dione, m.p. 234-235°C. The yield of pure product was 20% of the theoretical.

Analysis: Calculated for C11H8C12N2O3: c 46'02» H 2.81, N 9.76

Found: C 45.81, H 2.74, N 9.69.

Example XIX

A mixture consisting of 252 mg (0.001 mol) of 6'-fluoro-spiro-[imidazolidine-4,41-thiochroman]-2,5-dione (prepared as described in Example IX) in 10 ml of methylene chloride, together with 50 mg of a 40% aqueous solution of tetrabutylammonium hydroxide and 224 mg (0.01 mol) of sodium periodate in 5 ml of water was stirred at room temperature (about 25°C) for 1 hour. The precipitated solids thus obtained were then collected by suction filtration and recrystallized from ethanol (3 mL) to give 60 mg (22%) of pure 6<1->fluoro-spiro-[imidazolidine-4,4<1- >thiochroman]-2,5-dione-1'-oxide, m.p. 289-291°C.

Analysis: Calculated for C-^HgFt^O-jS: C 49.25, H 3.38, N 10.44

Found: C 49.27, H 3.35, N 10.35

Example XX

To a suspension of 0.595 g (0.00236 mol) of 6'-fluoro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione (prepared as described in Example IX) in 50 ml of chloroform in a 250 ml three-necked, round-bottomed reaction flask was added in small portions over a period of 1 hour 1.00 g (0.00579 mol) of m-chloroperoxybenzoic acid. The resulting slurry was then stirred at room temperature (about 25°C) for a period of 36 hours and was finally diluted with 500 ml of ethyl acetate. The yellow organic layer thus obtained was then washed with four 50 mL portions of saturated aqueous sodium bicarbonate solution, dried over anhydrous magnesium sulfate, filtered, and the solvent portion was then removed in vacuo to give 0.50 g (74.5%) of crude 6' -fluoro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione-1',1'-dioxide in the form of a white, crystalline residue. Recrystallization from ethanol/ethyl acetate/n-hexane then gave the pure material (m.p. 179-180°C with cleavage) as a first portion of fine white crystals (yield 0.295 g). Two further recrystallizations from ethanol/ethyl acetate raised the melting point of the analytical sample to 184-186°C (dec.).

Analysis:

Calculated for C^HgFN^S-O^CH^OOC^: C 47.55, H 3.99, N 8.53 Found: C 47.54, H 3.93, N 8.56.

Example XXI

The procedure described in Example XX was repeated, except that 0.234 g (0.001 mol) of spiro-[imidazolidin-4,41-thiochroman]-2,5-dione and 0.426 g (0.00247 mol) of m-chloro-peroxy -benzoic acid was reacted to give 0.20 g (75%) of pure spiro-[imida-zolidin-4,4'-thiochroman]-2,5-dione-1',11-dioxide. Recrystallization from methanol/ethanol/n-hexane then gave the analytical sample (m.p. 280-281°C).

Analysis: Calculated for .jH N^S: C 49.61, H 3.78, N 10.52

Found: C 49.82, H 3.85, N 10.19.

Example XXII

A mixture consisting of 1.0 g (0.00549 mol) of thioindan-3-one-1,1-dioxide (Regitz, Chemisene Berichte, vol. 98, p. 36

(1965)), 0.613 g (0.0094 mol) of potassium cyanide and 21.9 g (0.021 mol) of ammonium carbonate in 14 ml of 50% aqueous ethanol were placed in a 50 ml round bottom reaction flask and heated at 60°C for a period of 48 hours under a nitrogen atmosphere. The reaction mixture was then diluted with 70 ml of water, traces of solid material were removed by filtration, and the filtrate was then acidified with 6N hydrochloric acid. The precipitated product thus obtained was then recovered by filtration, redissolution in 4N aqueous potassium hydroxide and final acidification again with 6N hydrochloric acid. The acidified solution containing the product was saturated with sodium chloride and then extracted with six 150 mL portions of fresh ethyl acetate, and the resulting organic layers were then combined and dried over anhydrous magnesium sulfate. By removing the drying agent by filtration and the organic solvent by evaporation under reduced pressure, 0.50 g (36%) of pure spiro-[imidazolidine-3,3'-thioindane]-2,5-dicne was obtained, sm. p. 287°C (dec.) after two recrystallizations from ethanol/ethyl acetate/n-hexane.

Analysis: Calculated for C^HgN^S: C 47.61, H 3.20, N 11.11

Found: C 47.77, H 3.28, N 10.85.

Example XXIII

A mixture consisting of 2.75 g (0.01562 mol) 6,8-dimethyl-4-chromanone (Chemical Abstracts, vol. 58, p. 13900c (1964)), 3.5 g (0.0538 mol ) potassium cyanide and 10.5 g (0.109 mol) ammonium carbonate in 60 ml of 50% aqueous ethanol were placed in a 125 ml round-bottom reaction flask and heated in an oil bath at 65°C for a period of 48 hours under a nitrogen atmosphere. The reaction mixture was then cooled to room temperature (about 25°C) and filtered, and the resulting filtrate was then extracted with 50 ml of diethyl ether. The resulting aqueous layer was saved and then acidified to pH 2.0 with 3N hydrochloric acid (cooling was required). The cloudy mixture thus obtained was then extracted with three 200 ml portions of ethyl acetate, and the combined organic layers were then re-extracted with three 50 ml portions of 4N aqueous potassium hydroxide. The combined basic aqueous layers were acidified again to pH 2.0 with 3N hydrochloric acid in the same manner as before,

and was then saturated with sodium chloride before extraction with three 200 mL portions of fresh ethyl acetate. The combined organic layers were then dried over anhydrous magnesium sulfate and filtered. By removing the solvent from the filtrate by evaporation under reduced pressure, 2.50 g (65%) of 6,8-dimethyl-spiro-[chroman-4,4'-imidazolidine]-2<1>,5<1- >dion, sm.p. 185-190°C (decomposition). Two crystallizations from aqueous ethanol then gave analytically pure material (m.p. 188-189°C).

Analysis: Calculated for C2.3Hi4N2°3: C 63'40' H 5»73' N H-38

Found: C 63.05, H 5.69, N 11.33.

The following spiro-hydantoin compounds were tested for their ability to reduce or inhibit aldose reductase enzyme activity by the method of S. Hayman et al as described in the Journal of Biological Chemistry, vol. 240,

pp. 877 (1965) and as modified by K. Sastanj et al. in US Patent 3,821,383. In each case, the substrate used was partially purified aldose reductase enzyme obtained from calf lenses. The results obtained with each compound are expressed below

as percentage inhibition of the enzyme activity at the different concentrations examined:

The following spiro-hydantoin compounds were tested for their ability to reduce or inhibit sorbitol accumulation in the sciatic nerve of streptozotocinized (ie, diabetic) rats by the method substantially described in US Patent 3,821,383. During the examination, the amount of sorbitol accumulation in the sciatic nerves was measured 27 hours after the induction of diabetes. The compounds were administered orally in the indicated doses 4, 8 and 24 hours after the administration of streptozotocin. The results obtained in this way are given below expressed as % inhibition (%) obtained with the test compound compared to the case where no compound was administered (ie untreated animal where sorbitol levels normally rise from about 50-100 mM/g tissue to as high as 400 mM/g tissue during the trial period of

27 hours):

6-Fluoro-spiro-[chromane-4,4'-imidazolidine]-2<1>,5'-dione (the product of Example XVI) was investigated for its ability to lower already elevated sorbitol levels in streptozotocin-induced diabetics rats with a duration of 2 weeks (i.e. chronic) by administering said compound orally to the animals for a period of 7 days. In this examination, sorbitol determinations were made both in the sciatic nerve and in the lens. Streptozotocin was first administered to the animals in an amount of 65 mg/kg intravenously. The animals then remained untreated for a period of 2 weeks. At the end of this period, a "control group" of 8 rats (control group I) was euthanized to determine a baseline for sorbitol, while the remaining two groups of 7 animals each received either 6-fluoro-spiro-[chromane-4,4' -imidazolidine]-2',5'-dione in an amount of 2.5 mg/kg, twice daily, or just water alone (control group II). After 7 days the rats were sacrificed (three hours after dosing) and it was found that while the amount of sorbitol in the sciatic nerve of the control group (control group II) had risen slightly above the baseline values and the sorbitol values in the lens had stabilized with respect to the same line, it was achieved significant reductions in the amounts of sorbitol in both the sciatic nerve (68%) and the lens (71%) in the treated group (ie the animals that had received the aforementioned test compound). The ability of 6-fluoro-spiro-[chromane-4,4<1->imidazolidine]-2',5'-dione to prevent or inhibit galactitol formation in acute galactosemic rats was determined by administering said compound to the animals via their for a period of 7 days. In this study, normal male rats were first divided into groups of 6 animals each and then given a 30% galactose diet together with the compound to be administered in three different dosage amounts. One group of animals received 6-fluoro-spiro-[chromane-4,4'-imidazolidine]-2<1>,5'-dione in an amount of 10 mg/kg and another in an amount of 20 mg/kg. A control group of 9 animals received a 30% galactose diet without any compound. At the end of the 7-day period, the lenses were taken out for galactitol determination, and it was found that while the polyol amounts in the control group had risen from almost undetectable amounts to a value well above 30 ymol/g, it was in the rats that received the test compound in the diet in addition to galactose, a very marked inhibition of galactitol values at the two highest doses examined (eg 72% at 20 mg/kg and 40% at 10 mg/kg).

To determine the effect of 6-fluoro-spiro-[chroman-4,4'-imidazolidine]-2<1>,5'-dione on cataract formation in galactosemia, rats were fed a 30% galactose diet with and without this connection for a period of 29 days, and eye examinations were also carried out routinely approx. 2 times per week during this period. The experimental animals had the test compound mixed in the food in concentrations necessary to give doses of approx. 10 mg/kg and 20 mg/kg. Control animals received the galactose diet alone (ie, without the compound). After 8-14 days, it was found that lens opacities had developed in 90% of the eyes of the control animals, compared with no opacities in the rats that had received 6-fluoro-spiro-[chromane-4,4<1->imidazolidine ]-2',5'-dione in amounts of either 10 mg/kg or 20 mg/kg. At the end of a 17-day period, opacities were found to be present in 100% of the eyes of the control animals, while only 6% of the eyes of the rats receiving 6-fluoro-spiro-[chromane-4,4'-imidazolidine] -2<1>,5'-dione in an amount of 10 mg/kg was affected.

The corresponding value in the rats that received the test compound i

an amount of 20 mg/kg, was 0%. This delay in cataract formation continued in all treated groups until 22 days had passed, at which time lens opacity was observed in more than 90% of the eyes of the animals receiving the test compound at an amount of 10 mg/kg. However, the rats receiving 6-fluoro-spiro-[chroman-4,4'-imidazolidine]-2',5'-dione in an amount of 20 mg/kg showed a significant delay in cataract formation which was still observed after 29 days course, which was evident from the fact that only 37% of the eyes of the animals in the treated group had lens opacity.

The effectiveness of 6-fluoro-spiro-[chromane-4,4'-imidazolidine]-2',5'-dione in delaying cataract development in rats is demonstrated by the test method described immediately above by carefully assessing the degree of lens opacification. In this examination, the percentage of the lens area was examined over the period of 29 days, and the results obtained serve as an index of how severe the attack was. In this way, it was found that after 17 days, 75% of the control lenses showed an area that was attacked, which was never less than 10%. Similarly, values of 6% and 0% respectively were found for the rats that received 6-fluoro-spiro-[chroman-4,4'-imidazolidine]-2<1>,5'-dione in amounts of 10 mg/kg and 20 mg/kg. The degree of lens opacification in the treated groups was always less than that found in the control group, including the values obtained at the end of the 29-day course.

Claims (6)

1. Analogous process for the preparation of a therapeutically active spiro-hydantoin compound of the formula: and the base salts thereof with pharmacologically acceptable cations, where A is where X is hydrogen and X 2 is fluorine, hydroxy or 6'-(lower alkoxy); or X and X 2 are each lower alkoxy or are together -OCH l0(CH i„) n 0- where n is 0 or 3 is 1; 4X <3> is hydrogen and X 4 is 7'-(lower alkoxy); or X and X are each lower- 5 6 alkoxy; X is hydrogen, and X is fluoro, chloro, bromo or lower alkoxy; or X <5> and X <6> are each chlorine or lower 7 8 alkoxy; X is hydrogen and X is hydrogen or fluorine, Y is oxygen or sulfur; and provided that X5 and X6 are alkyl only if Y is oxygen, and X D is hydrogen and X <6>is chlorine or bromine only if Y is sulfur, characterized in that a suitable carbonyl ring compound of the formula where A is as stated above, is reacted with an alkali metal cyanide and ammonium carbonate, and optionally a spiro-hydantoin product where Y is sulphur, is oxidized to a product where Y is converted to Q to give a compound where A has formula VIII, and optionally a spiro-hydantoin product where X 2 is lower alkoxy is converted into a compound where X 2 is hydroxy; and optionally, a spiro-hydantoin product prepared according to one of the steps described above is converted into a pharmacologically acceptable base salt thereof. 2. Method as stated in claim 1, characterized in that the spiro-hydantoin compound that is produced is 6-fluoro-spiro-[chroman-4,4'-imidazolidine]-2',5'-dione. 3. Method as stated in claim 1, characterized in that the spiro-hydantoin compound that is produced is 6,7-dichloro-spiro-[chroman-4,4'-imidazolidine]-2<1>,5<1->dione. 4. Method as stated in claim 1, characterized in that the spiro-hydantoin compound that is produced is 6,8-dichloro-spiro-[chroman-4,4'-imidazolidine]-2',5'-dione. 5. Method as stated in claim 1, characterized in that the spiro-hydantoin compound that is produced is 6<1->fluoro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione. 6. Process as stated in claim 1, characterized in that the spiro-hydantoin compound that is produced is 6',7<1->dichloro-spiro-[imidazolidine-4,4'-thiochroman]-2,5-dione.