FR2475553A1 - Aldose reductase inhibitor spiro-oxazolidine:di:one derivs. - prepd. from benzopyran, benzo:thiopyran, benzofuran and benzothiophene cpds. (BE 20.2.80) - Google Patents

Abstract

New spiro-oxazolidinedione derivs. are of formula (I) and their pharmaceutically acceptable salts (where X is O or S; n is 1 or 2; R is H, 1-4C alkyl, benzyl or benzyl monosubstd. by Cl, Br, F, OH, 1-3C alkyl or 1-3C alkoxy; and R1, R2 and R3 are H, Cl, Br, F, 1-3C alkyl, phenyl or phenyl monosubstd. by Cl, Br, F, OH, 1-3C alkyl or 1-3C alkoxy). (I) are aldose reductase inhibitors useful as agents for relieving or preventing the complications of chronic diabetes, such as diabetic cataracts, neuropathies and retinophaties. Dosage is ca. 1-500 (pref. ca. 1-25) mg/kg/day.

Description

The present invention relates to novel spiro-oxazolidine-diones which are of interest for the treatment of certain chronic complications resulting from diabetes mellitus, for example diabetic cataracts and neuropathy, intermediates for their preparation and pharmaceutical compositions which contain these new compounds.

Various attempts have been made in the past to obtain new effective oral anti-diabetic agents. Generally, these efforts have involved the synthesis of new organic compounds, including sulfonylureas and the determination of their ability to significantly reduce blood sugar levels when administered orally. However, little is known about the ability of these organic compounds to prevent or alleviate chronic complications of diabetes such as diabetic cataracts, neuropathy and retinopathy. United States patent No. 3,821,383 discloses that aldosereductase inhibitors such as 1,3-dioxo-1H-benz [d, e-isoquinoline-2- (3H) -acetic acid and its derivatives are useful for the treatment of these conditions. These aldosereductase inhibitors work by inhibiting the activity of the enzyme called aldose reductase, which is primarily responsible for regulating the reduction of aldoses such as glucose and galactose to corresponding polyols such as sorbitol and galactitol. In humans and other animals, it is possible to prevent or reduce undesirable accumulations of galactitol in the lens of galactosemic subjects and undesirable accumulations of sorbitol in the lens, peripheral nerve cord and kidneys. various diabetic subjects. Consequently, these compounds are of therapeutic interest as aldosereductase inhibitors in the fight against certain chronic diabetic complications such as complications of an ocular nature, since it is known in practice that the presence of polyols in the lens leads to the development of cataracts, with a concomitant decrease in the transparency of the lens.

(et leurs sels acceptables du point de vue pharmaceutique), formule dans laquelle X est un atome d'oxygène ou de soufre, n est égal à 1 ou 2 ;R est un atome d'hydrogène ou un groupe aîy?e yant 1 a 4 atomes de carbone, benzyle ou benzyle monosubstitué dont le substituant est choisi entre les radicaux chlore, bromo, fluoro, hydroxy, alkyle en C1-C3 et alkoxy en C1-C3 ;1et R1, R2 et R3 représentent chacun un atome d'hydrogène ou un radical chloro, bromo, fluoro, alkyle en C1-C3, phényle ou phényle monosubstitué dont le substituant est un radical chloro, bromo, fluoro, hydroxy, alkyle en C1-C3 ou alkoxy en C1-C3. The present invention provides novel aldose reductase inhibitors which are useful for use as therapeutic agents for preventing or alleviating chronic diabetic complications. The compounds of the present invention are new spiro-oxazolidine-dicnes of formula

(and their pharmaceutically acceptable salts), formula in which X is an oxygen or sulfur atom, n is 1 or 2; R is a hydrogen atom or an elder group having 1 a 4 carbon atoms, benzyl or monosubstituted benzyl, the substituent of which is chosen from chlorine, bromo, fluoro, hydroxy, C1-C3 alkyl and C1-C3 alkoxy; 1 and R1, R2 and R3 each represent a hydrogen atom or a chloro, bromo, fluoro, C1-C3 alkyl, phenyl or monosubstituted phenyl radical whose substituent is a chloro, bromo, fluoro, hydroxy, C1-C3 alkyl or C1-C3 alkoxy radical.

A group of preferred compounds includes the compounds in which X is an oxygen atom and in particular those in. which n is equal to 1. Preferably, R is a hydrogen atom and R1, R2 and R3 each represent a hydrogen atom or a chloro1 bromo or fluoro radical.

Among these compounds, particularly preferred are those in which R2 and R3 each represent a hydrogen atom, as well as those in which R1 is a hydrogen atom or a chloro, bromo or fluoro radical, in particular a chloro radical. Also appreciated are the compounds in which R1 is a chloro radical, R2 is a hydrogen atom and R3 is a chloro radical and those in which R1 is a chloro radical, R2 is a hydrogen atom and R3 is a methyl group.

Another group of compounds of interest is the group of compounds in which X is a sulfur atom, in particular when n is equal to 1. Preferably, R is a hydrogen atom and R1, R2 and R3 each represent an atom of hydrogen or a chloro, bromo or fluoro radical.

Particularly appreciated are the compounds in which R2 and R3 are each a hydrogen atom, as well as those in which R1 and a hydrogen atom or a chloro or fluoro radical.

The present invention also relates to useful intermediate compounds for use in the preparation of the spiro-oxazolidine-diones of formula I.

dans laquelle R1, R2, R3, X et n ont les définitions données ci-dessus et R4 est un groupe alkyle ayant 1 a 4 atomes de carbone, un groupe benzyle ou un groupe benzyle monosubstitué dont le substituant est un radical chloro, bromo, fluoro, hydroxy,alkyle ayant 1 a 3 atomes de carbone et alkoxy ayant 1 à 3 atomes de carbone. Thus, the invention covers the compounds of formula

in which R1, R2, R3, X and n have the definitions given above and R4 is an alkyl group having 1 to 4 carbon atoms, a benzyl group or a monosubstituted benzyl group the substituent of which is a chloro, bromo radical, fluoro, hydroxy, alkyl having 1 to 3 carbon atoms and alkoxy having 1 to 3 carbon atoms.

dans laquelle R1, R2, R3, R4, X- et n ont les définitions données ci-dessus.Other intermediate compounds in accordance with the present invention are the compounds of formula

in which R1, R2, R3, R4, X- and n have the definitions given above.

Preferred compounds of formulas II and III are the compounds of interest to be used for the preparation of the preferred spiro-oxazolidine-diones of the invention, according to the definitions given above, that is to say the compounds in which the variables R1, R2, R3, X and n have the corresponding preferred values. R4 is preferably an alkyl group having 1 to 3 carbon atoms, in particular an ethyl group.

dans laquelle X et n ont les définitions données ci-dessus et R11, R2' et R31 représentent chacun un atome d'hydrogène ou un radical chloro ou alkyle ayant 1 à 3 atomes. de carbone. Un groupe apprécié de composés est formé des compo sés dans lesquels X est un atome d'oxygène, n est egal à 1
5 et R1', R2' et R3' représentent chacun un atome d'hydrogène ou un radical chloro ou méthyle.Parmi ces composés, on apprécie ceux dans lesquels R1' est un radical chloro et R2', R3, représentent chacun un atome d'hydrogène, ainsi que ceux dans lesquels R1' et R3, sont chacun un radical chloro et R2 est un atome d'hydrogène. Un composé apprécié dans le groupe de composés pour lesquels X est un atome de soufre et n est égal à 1, est le composé dans lequel R1' est un radical chloro et chacune des variables R2, et R3, est un atome d'hydrogène.Les composés de la présente invention permettent le traitement d'un sujet diabétique en vue de prévenir ou d'atténuer des complications associées au diabète, par exemple la cataracte, la neuropathie et la rétinopathie, par administration à- l'hôte d'une quantité efficace d'un composé de formule I.Other intermediate compounds of the present invention are the compounds of formula:

in which X and n have the definitions given above and R11, R2 'and R31 each represent a hydrogen atom or a chloro or alkyl radical having 1 to 3 atoms. of carbon. A valued group of compounds is composed of compounds in which X is an oxygen atom, n is equal to 1
5 and R1 ', R2' and R3 'each represent a hydrogen atom or a chloro or methyl radical. Among these compounds, we appreciate those in which R1' is a chloro radical and R2 ', R3, each represent a d atom 'hydrogen, as well as those in which R1' and R3, are each a chloro radical and R2 is a hydrogen atom. A compound appreciated in the group of compounds for which X is a sulfur atom and n is equal to 1, is the compound in which R1 'is a chloro radical and each of the variables R2, and R3, is a hydrogen atom. The compounds of the present invention allow the treatment of a diabetic subject in order to prevent or alleviate complications associated with diabetes, for example cataracts, neuropathy and retinopathy, by administering to the host an amount effective of a compound of formula I.

The present invention further relates to a pharmaceutical composition which comprises a pharmaceutically acceptable carrier or vehicle and which contains a compound of formula I in an amount effective to prevent and alleviate complications associated with diabetes such as cataracts, neuropathy and retinopathy.

dans laquelle R1, R2, R3, X et n ont les définitions déjà données. Ces composés sont faciles à obtenir ou peuvent être prépares par diverses voies de synthèse.The new spiro-oxazolidine-diones of formula
I are prepared from suitably substituted ketones of formula

in which R1, R2, R3, X and n have the definitions already given. These compounds are easy to obtain or can be prepared by various synthetic routes.

The reaction sequence for the formation of compounds of formula I is illustrated in reaction scheme A which will be referred to in connection with the comments which follow.

DIAGRAM A

By way of example, the nomenclature adopted in the description below corresponds to compounds in which n is equal to 1. However, it should be noted that analogous compounds in which n is equal to 2 are also formed by the reactions described below starting from the suitably chosen starting ketone.

The ketone la is first of all reacted with a trialkylsilyl cyanide of formula (R ') 3SiCN, to form the derivative 4-cyano-4-trialkylsilyloxy 2a. A preferred trialkylsilyl cyanide in this reaction is trimethylsilyl cyanide, although other trialkylsilyl cyanides with lower alkyl radicals, each having 1 to 4 carbon atoms, can be used. The reaction is carried out in the presence of a catalyst of the type of a Lewis acid, such as a zinc halide, an aluminum halide or boron trifluoride, the zinc iodide constituting a catalyst of choice. Temperatures are generally used from about 0 to 500 ° C. and preferably from about 0 to 20 ° C., in an inert organic solvent which is usually an ether such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxane, etc.Compound 2a is then converted to an alkyl 4-hydroxy-4-carboximidate 4 by reaction with an acid in an alcoholic solvent R4OH, suitable acids include hydrogen halides, especially hydrogen chloride.

The alcohol R4OH can be a lower alkanol having 1 to 4 carbon atoms, benzyl alcohol or a substituted benzyl alcohol whose substituent can be a chloro, bromo, fluoro, hydroxy, alkyl radical having 1 to 3 carbon atoms or alkyl having 1 to 3 carbon atoms. The reaction is generally carried out at temperatures of about -10 to about 250C and preferably about 0 to 10C.

4-hydroxy-4-carboximidate 4 can also be prepared from the starting ketone la, passing through the cyanhydrin derivative 3a. The latter is formed by reaction of the ketone with liquid hydrogen cyanide, in the presence of a base such as piperidine, pyridine, etc., at a temperature of about 0 to 500 ° C. and preferably about 0 to 100 ° C. , by the procedure described by
Stoughton in "JACS," 63, 2376 (1941). The cyanohydrin is then converted to 4-hydroxy-4-carboxinidate 4 by means of a hydrogen halide in an alcohol used as solvent, as described above with regard to the transformation of compound 2a into compound.

Cyanohydrin 3a can also be formed at. from the derivative 4-cyano-4-trialkylsilyloxy 2a and it can be isolated as an intermediate compound during the initial stages of conversion from 2a to 4 by reaction with a hydrogen halide and a suitably chosen alcohol, as indicated in the above .

4-hydroxy-4-carboximidate 4 can be converted directly to spiro-oxazolidine-2,4-dicn 6a by various methods. In all cases, spiro-oxazoline-2-one 5 is an intermediate compound and can, if necessary, be isolated from the reaction mixture. However, it is generally preferable to convert the compound 4 to compound 6a directly, without this isolation of the intermediate compound 5. The 4hydroxy-4-carboximidate can be caused to react with phosgene in the presence of a base such as triethylamine or d other trialkylamines having 1 to 4 carbon atoms in each alkyl group, in an inert organic solvent such as an ether, for example diethyl ether, tetrahydrofuran, dimethoxyethane, dioxane, etc. Generally, the phosgene in the reaction solution at a temperature of about -10 to about + 100C for about 15 to 75 minutes and the solution is then stirred at about 20-500C, preferably at room temperature, for about 12 to 48 hours, the spiro-oxazoline-2-one 5 then being formed in a predominant proportion.

This intermediate compound can then be converted into the desired spiro-oxazolidine-2,4-dione 6a by prolonged bubbling of phosgene at a temperature of about -10 to +10 C for about 15 to 75 minutes, followed by stirring at room temperature for another 12 to 48 hours approx. Alternatively, an alkali metal carbonate such as potassium or sodium carbonate, or ammonium carbonate may be added to the solution of intermediate compound 5 and the mixture may be stirred at a temperature of about 15 to about 500C, preferably around room temperature, for a period of about 6 to 24 hours to form the desired 2,4-dione spiro-oxazolidine
The desired spiro-oxazolidine-2,4-dione can also be prepared from 4-hydroxy-4-carboximidate 4 by reaction with an alkyl haloformate, the alkyl group of which comprises 1 to 4 carbon atoms, a preferred reactant being ethyl chloroformate. The reaction is generally carried out by stirring intermediate compound 4 as well as the alkyl haloformate in an inert solvent such as pyridine, at a temperature of around -10 to + 150 ° C., preferably at about OOC for a period of about 30 minutes to about 2 hours, this operation being followed by heating the solution to an elevated temperature, from about 50 to about 1500C and preferably from about 90 to 1200C, for example at reflux temperature in pyridine, for a period of about 2 to 6 hours. If necessary, the intermediate spiro-oxazoline-2-one 5 can be isolated from the initial reaction mixture after heating the solution for relatively short periods, for example for about 1 hour.

Spiro-oxazolidine-2,4-diones can also be prepared from intermediate compound 4 by reaction with 1, l'-carbonyldimidazole, the reaction generally being carried out at a temperature of about 50 to 1500C and preferably about 80 to 1100C, solvent free or in an inert organic solvent such as dioxane, tetrahydrofuran, dimethoxyethane, dimethyl ether, etcb for a period of about 12 to 36 hours.

If desired, the intermediate spiro-oxazoline-2-one can be obtained by heating for a relatively short period only, for example for a period of about 30 to 90 minutes.

Another preparation process available for some of the substituted spiro-oxazolidine-2,4-diones of the invention is illustrated by reaction scheme B, which will be referred to in connection with the following comment.

By way of example, the nomenclature adopted in the following commentary refers to compounds in which n is equal to 1. However, it should be noted that analogous compounds in which- n is equal to 2 are also formed by the reactions described below after starting with the suitably chosen starting ketone.

DIAGRAM B

The starting components are ketones of formula lb in which R1 ,, - R2 'and R3' are chosen from hydrogen and chloro and alkyl radicals
C1-C3 while X and n have the definitions-already given.

The first step is the formation of the 4-cyano-4trimethylsilyloxy 2b derivative or of cyanohydrin 3b under the reaction conditions and with the reagents already described with regard to the transformation of the compound la into respective compounds 2a and 3a The intermediate compounds 2b and 3b are converted to amide 7 by treatment with an acid such as hydrochloric or sulfuric acid concentrated in aqueous solution at a temperature of about 0 to 300C. For example, the reaction can be carried out by bubbling anhydrous hydrochloric gas into a solution of compound 2b or -3b in concentrated hydrochloric acid at about 0-50C for about 5 to 30 minutes, then stirring at about 15 to 350C for a period of approximately 6 to 24 hours.

Amide 7 can be converted into the desired spiro-oxazolidine2,4-dione 6b by reaction with a dialkyl carbonate such as diethyl carbonate, in the presence of an alkali metal alcoholate such as sodium tert-butylate or potassium tert-butoxide in a normal alkanolic solvent having 1 to 6 carbon atoms, such as n-butanol. The reaction is generally carried out by heating the mixture to about 70-1500C and preferably about 100-1250C for about 12 to 72 hours.

Amide 7 can also be converted into the desired spirooxazolidine-2,4-dione by reaction with ethyl chloroformate by methods analogous to those which have been described by Stoughton in "JACS" 63, 2376 (1941),
The production of compounds of formula I in which
R is an alkyl, benzyl or substituted benzyl group is carried out by continuing the reaction of the compounds in which R is a hydrogen atom so as to introduce the desired substituent, by alkylation operations well known in the art. can also be prepared by similar reaction of 4-hydroxy-4-carboximidate 4 of reaction scheme A so as to form the corresponding compound carrying an alkyl or benzyl substituent on the nitrogen atom, then transformation into spiro-oxazolidine -2,4-dione substituted on the nitrogen atom, as described with regard to the conversion of compound 4 to compound 6a.

The spiro-oxazolidine-2,4-diones of the invention, formed in the manner described above, can be easily isolated from the reaction medium by conventional operations, for example by evaporation of the solvent followed by extraction with ether and chloroform and recrystallization from toluene or a similar aromatic solvent.

Pharmaceutically acceptable salts can be prepared without difficulty from compounds of formula I in which R is a hydrogen atom, by conventional procedures. Thus, these salts can be easily prepared by treatment of spiro-oxazolidine-2,4diones with an aqueous solution of the cation acceptable from the pharmaceutical point of view desired then evaporation to dryness of the resulting solution, preferably under reduced pressure. Alternatively, a solution of spirooxazolidine-2,4-dione in a lower alkanolic acid can be mixed with an alcoholate of the desired metal and the solution can then be evaporated to dryness. Pharmaceutically acceptable cations which are suitable for this purpose include, without limitation, potassium, sodium, ammonium, calcium and magnesium cations.

It should be noted that the new spiro oxazolidine - 2,4-diones of the present invention contain a center of asymmetry and therefore have optical isomerism. If necessary, the racemic spiro-oxazolidine2,4-dione formed by the methods described above can be split into the d and 1 isomer forms by application of conventional splitting methods. For example, cinchonidine can be used to form selective - ment an adduct with the dextrorotatory isomer, for example, 6-chlorospiro-E 4H-2,3-dihydrobenzopyranne (4,5l) oxazolidin 1-2 ', 4'-dione. Then, the dextrorotatory isomer can be easily obtained from the isolated adduct, for example by treatment with a mineral acid such as hydrochloric acid then extraction with a suitable organic solvent such as ethyl acetate, etc. . The levorotatory isomer can also be isolated from the liquor after removal of the adduct formed separately with the dextrorotatory isomer. It is also possible to obtain the levorotatory isomer by formation of an adduct with l-amphetamine, followed by Subsequent reaction of the adduct with an acid to form the free isomer. Isomers 1 (i.e. isomers with negative optical rotation) of 6-chloro-spiro [4H-2,3- dihydrobenzopyranne (4,5 ') oxazolidin l-2', 41-dione and 6,8-dichloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidin] 2', 4'-dione are of particular interest as aldose reductase inhibitors.

Where appropriate, an optical isomer of configuration d or 1 can be converted into its corresponding epimer by methods analogous to those which have been described by A.K.

Bose, in the Tetrahedron Letters ", 1973, 1619. The optical isomer obtained by the splitting operations described above is thus first treated with a base such as an alkali metal hydroxide, for example the sodium or potassium hydroxide, at about 0-1000C in a solvent such as water, an alcohol, an ether such as dioxane or mixtures of these solvents. Spiro-oxazolidinedione is thus converted into 4-hydroxy- precursor carboxamide (formula 7 indicated in reaction scheme B) with the same configuration as the initial spiro-oxazolidine-dione.

This carboxamide 7 is then reacted with a dialkyl azodicarboxylate such as diethyl azodicarboxylate or its lower alkyl analogs, in the presence of a trivalent phosphorus compound such as a triarylphosphine, for example triphenylphosphine, and a carboxylic acid such as formic acid or benzoic acid.

The reaction is generally carried out at a temperature of about 0 to 1500C in an inert organic solvent such as tetrahydrofuran. The product of this reaction is the ester of the corresponding epimeric 4-hydroxycarboxamide, that is to say the formate or benzoate of the carboxamide of formula 7 epimerized in position 4. The ester group is then hydrolyzed by treatment with a base such than an alkali metal hydroxide to form the 4-hydroxycarboxamide of formula 7 epimerized in position 4, that is to say of configuration opposite to that of the initial split spiro-oxazolidinediones. The epimerized 4-hydroxycarboxamide is then converted to the epimer of the initial spiro-oxazolidinediones by the methods described above with regard to the transformation of compound 7 into compound 6b. Racemization can take place to a certain degree during successive reactions above. The desired optical isomer can then be obtained by the splitting operations already described. Using the above method, it is possible to obtain from the corresponding epimer an isomer of spiro-oxazolidine-dione of activity appreciated as an agent for inhibiting aldose ~ reductase. Thus, for example, the 1-isomers of 6-chloro-spiro- (4H-2,3-dihydrobenzopyranne (4,5 ') - oxazolidine] -2 ", 4'-dione and 6,8-dichloro- spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidinej-2' 14 '-dione can be obtained from the corresponding d isomers.

The novel spiro-oxazolidine-2,4-diones of the invention are useful as aldose reductase inhibitors and as such are of therapeutic interest in the treatment of chronic complications of diabetes, such as cataracts, retinopathy and neuropathy. The term treatment used herein includes preventive and curative treatment for these conditions. The compounds can be administered to a subject in need of such treatment by a variety of conventional routes of administration, e.g., orally and parenterally. In general, these compounds are administered at doses of from about 1 to 500 mg per kg of body weight of the subject to be treated per day, preferably at the daily dose of approximately 1 to 25 mg / kg. However, certain differences in dosage necessarily appear depending on the state of the subject being treated and the particular compound which one chooses to use, and the doctor is able in each case to determine the dose which is suitable for the individual patient.

The compounds of the invention can be administered alone or in combination with pharmaceutically acceptable carriers, in a single dose or in multiple doses. Suitable pharmaceutical carriers include inert solid diluents or fillers, sterile aqueous solutions and various non-toxic organic solvents. The pharmaceutical compositions formed by combining a spiro-oxazolidine-2,4-dione and a pharmaceutically acceptable carrier or vehicle are then easily administered in various dosage forms such as tablets, powders, cachets, syrups, solutions for injection, etc. These pharmaceutical compositions may, if appropriate, contain other ingredients such as perfumes, binders, excipients, etc. Thus, for oral administration, tablets containing various excipients such as sodium citrate, carbonate of calcium and calcium phosphate can be used in combination with various disintegrating agents such as starch, preferably potato or cassava starch, alginic acid and certain silicates. complexes, as well as binders such as polyvinylpyrrolidone, sucrose, gelatin and gum arabic. In addition, lubricants such as magnesium stearate, sodium lauryl sulfate and talc are often useful for making tablets. Solid compositions of a similar type can also be used. as fillers in capsules filled with ~ soft and hard gelatin; preferred substances for this purpose include lactose or milk sugar and high molecular weight polyethylene glycols. When it is desired to obtain aqueous suspensions or olixirs for oral administration, the essential active ingredient of these forms can be combined with various sweeteners or various perfumes, a coloring matter or dyes and, where appropriate, emulsifiers or suspending agents, as well as diluents such as water, ethanol, propylene glycol, glycerol and mixtures thereof.

for parenteral administration, solutions of spiio-oxazolidine-2,4-diones in sesar oil or peanut oil or in polypropylene glycol alux can be used, as well as sterile aqueous solutions of the corresponding water-soluble salts of aldalin metals or alkaline earth already described. These aqueous solutions must be properly buffered, if necessary, and the liquid diluent must first be made isotonic by the addition of a sufficient amount of sodium chloride or glucose. These particular aqueous solutions are very suitable for intravenous, intramuscular, subcutaneous or intraperitoneal injection. In this connection, the sterile aqueous media used are all easily obtained by conventional techniques well known to those skilled in the art. In addition, it is also possible to administer a spiro-oxazolidine-2,4-dione topically, using a suitably selected ophthalmic solution which can then be poured into the eye dropwise.

The activity of the compounds of the present invention in the fight against chronic diabetic complications can be determined by various conventional biological or pharmacological tests. Suitable tests include (1) measuring the ability of the compounds to inhibit the enzymatic activity of the isolated aldose reductase; (2) measuring their ability to reduce or inhibit the accumulation of sorbitol in the sciatic nerve of rats given an acute dose of streptozotocin (i.e. diabetic rats), (3) measuring their ability to inject already high levels of sorbitol into the sciatic nerve and lens of rats with chronic diabetes under the influence of streptozotocin; (4) measuring their ability to prevent or inhibit the formation of galactitol in the lens of rats with acute galactoseemia and (5) measuring their ability to delay the development of cataracts and reduce the severity of opacity of the lens in rats with chronic galactosemia. Suitable experimental methods are described in U.S. Patent No. 3,821,383 as well as in the aforementioned references.

The invention is illustrated by. following examples, given without limitation.

EXAMPLE 1 6-chloro-4-cyano-4-trimethylsilyloxy-4H-2,3-dihydrobenzopyran
A mixture of 20.0 g (0.11 mole) of 6-chloro-4H-2,3-dihydrobenzopyran-4-one (Aldrich), 13.0 g (0.13 mole) of cyanide is stirred for 18 hours trimethylsilyl (Silar) and 0.2 g of zinc iodide in Alfa medium, in 50 ml of ether. The solution is discolored by adding charcoal (Darco), filtered and evaporated under vacuum to obtain an orange-colored oil which gives, by addition of pentane, crystals of 6-chloro-4-cyano4-trimethylsilyloxy- 4H-2, 3-dihydrobenzopyran (26.4, 84% g) melting at 67-69 C.

EXAMPLE 2 6-chloro-4 - hydroxy-4H-2,3-dihydrobenzopyra-n-ne-4-carboximi date of ethyl
A saturated solution of 273.0 g (0.97 mole) of 6-chloro-4-cyano-4-trimethylsilyloxy-4H-2,3-dihydrobenzopyran in 2.0 l of ethanol is cooled to 00C. bubbling anhydrous hydrochloric gas for 40 minutes
A slightly exothermic reaction takes place, while the mixture becomes homogeneous After having maintained the mixture for 16 hours at 40C, they are removed. volatile substances under vacuum and a semi-solid residue is obtained. By trituration with 800 ml of diethyl ether followed by filtration, a solid substance is obtained which is divided between 3.8 liters of chloroform and 500 ml of saturated sodium bicarbonate. The organic phase is washed with an additional 500 ml of saturated sodium bicarbonate, then it is dried over magnesium sulfate, filtered and evaporated in vacuo giving 193.0 g (78%) of 6-chloro-4- hydroxy-4H-2, 3-dihydrobenzopyranne-4-carboxi - ethyl midate. After trituration in ether, the product melts at 124-1260C.

EXAMPLE 3 6-chioro-spiro [4H-2, 3-dihydrobenzopyranne- (4,51) -oxazolidine] -2 ', 4'-dione
The mixture is bubbled through a mixture of 500 g (1.95 moles) of ethyl 6-chloro-4-hydroxy-4H-2, 3-dihydrobenzopyranne-carboximidate and 400 g (3.96 moles) of triethylamine in 13 liters of anhydrous tetrahydrofuran at 50C, 1818 g (18.4 moles) of phosgene at a flow rate chosen so as to maintain the temperature below 270C. Stirring is continued during the bubbling and the concomitant formation of a precipitate. After bubbling, the temperature is allowed to rise to 200C and the mixture is kept at this temperature for 48 hours. Analysis by thin layer chromatography shows a stain of
Rf equal to 0.57 and reveals the absence of spot at an Rf of 0.29. (Chloroform: ethyl acetate 1: 1 on silica gel).

(The material of Rf equal to 0.29 is the starting imidate while the material of Rf equal to 0.57 is the intermediate ethoxyoxazoline-2'-one of Example 6 given below). The mixture is then poured into 13 liters of crushed ice, with stirring, with the release of phosgene and carbon dioxide. The mixture of two phases is neutralized with 50% sodium hydroxide (1.7 liters) until the pH is equal to 7. 248 g (2.0 moles) of sodium carbonate are then added and the mixture is stirred for 16 hours at 200C. The product is isolated by the following extraction operation: 12 liters of ethyl acetate are added to the mixture and, after shaking, the aqueous phase is collected. The organic phase is washed twice with 12 liters of 7% sodium bicarbonate. The combined aqueous phases are acidified to pH equal to 1 by addition of concentrated hydrochloric acid, while being cooled to lO-150C. The aqueous phase is extracted three times with 12 liters of ethyl acetate The combined organic phases are washed with 12 liters of saturated sodium chloride, dried over magnesium sulfate, filtered and evaporated in vacuo giving 392 g (79% ) a solid substance melting at 191-195 C.

By recrystallization from toluene, 6-chlorospiro [4H-2,3-dihydrobenzopyran (4,5 ') oxazolidiine] -2', 4'dione melting at 196-1980C is obtained; Rf = Q, 44 (CHC13: EtOAc at 1: 1 on silica).

EXAMPLE 4 6-chloro-spirol4H-2,3-dihydrobenzopyran (4,5 ') oxazolidine] -2', 4'-dione
Heated for 16 hours at 900C in 5 ml of dioxane a mixture of 5.0 g (0.019 mol) of ethyl 6-chioro-4-hydroxy-4H-2,3-dihydrobenzopyranne-4-carboximidate and of 3, 7 g (0.023 mole) of 1,1'-carbonyl-diimidazole (Aldrich) Analysis of the reaction mixture by thin layer chromatography after one hour shows a spot of Rf equal to 0.57 (chloroform: acetate d (1: 1 ethyl on silicic acid) which corresponds to the ethoxy-oxazoline-2'-one of Example 6 described below. After cooling, the mixture is diluted with 100 ml of ethyl acetate and washed twice with 100 ml of 1N hydrochloric acid. The organic phase is extracted twice with 100 ml of saturated sodium bicarbonate. The basic phase is acidified with 6N hydrochloric acid to a pH of 1 and extracted three times. with 100 ml ethyl acetate. This last organic phase is washed with brine, dried over magnesium sulfate, filtered and evaporated in vacuo to give 1.20 g (25%) of solid substance melting at 189-191 C. By recrystallization from toluene, 6-chloro-spiro [4H-2,3-dihydrobenzo-pyran (4,5 ') oxazolidine] -2', 4'-dione melting at 192-1930C is obtained.

EXAMPLE 5 6-chloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] -2', 4'-dione
A mixture of 2.00 g (2.82 moles, ethyl chloroformate, 1.69 g (1.56 mmol) of 6-chloro-4-hydroxy-4H-2 is reacted at 0 ° C. for 1 hour. , Ethyl 3-dihydrobenzopyran-4-carboximidate and 5 ml of pyridine, then the mixture is allowed to warm to room temperature and finally it is refluxed for 4 hours by concentration under vacuum and extraction as described in 'Example 3, 6-chloro-spiro [4H-2,3-dihydrobenzopyranne (4,5') oxazolidine] -2 ', 4'-dione is obtained in a yield of 10%, melting at 195-198 C.

EXAMPLE 6 6-chloro-4'-ethoxy-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazoline] -2'-one
A solution of 1.15 g (4.00 mmol) of ethyl 6-chloro-4-hydroxy-4H-2,3-dihydrobenzopyranne4-carboximidate in 60 ml of tetrahydrofuran is cooled to 0 ° C. and stirred while therein. bubbling phosgene for 5 minutes. After 30 minutes, analysis by thin layer chromatography of the reaction mixture reveals a new spot of Rf equal to 0.57 (chloroform: ethyl acetate 1: 1 on silicic acid) and reveals the absence of starting imidate of Rf equal to 0.29. The mixture is poured onto 90 ml of ice and water mixture and it is extracted twice with 50 ml of ethyl acetate. The organic phases are washed twice with 30 ml of 5% sodium bicarbonate, dehydrated over magnesium sulfate, filtered and evaporated under vacuum, which gives an oil (0.651 g) which is crystallized at low temperature in a mixture of ether and hexane; yield 0.350 g (31%), melting point 108-110 C. This ethoxy-oxazoline is also prepared in a yield of 62% from the imidate, using ethyl chloroformate in pyridine.

EXAMPLE 7 6-chloro-spiro [4H-2,3-dihydrobenzopyran (4,5 ') oxazolidine) 2', 4'-dione
A mixture of 100 mg (0.355 mmol) of 6-chloro-4'-ethoxy-spiro [4H-2,3dihydrobenzopyranne (4,5 ') oxazoline] -2'-one and 88 is stirred at 20 ° C. for 16 hours. mg (0.710 mmol) of sodium carbonate in 2 ml of a 1: 1 mixture of tetrahydrofuran and water. After addition of 10 ml of ethyl acetate and 10 ml of water, 63 mg (70%) of 6-chloro-spiro [4H-2) are obtained by extraction as described in Example 3 , 3-dihydrobenzopyranne (4,5 ') oxazolidine] 2', 4'-dione melting at 192-1950C.

EXAMPLE 8 6-chloro-4-hydroxy-4H-2! 3-dihydrobenzopyranne-4-carbox
Anhydrous hydrochloric gas is bubbled at 0 ° C. for 5 minutes in a mixture of 1.40 g (5.0 mmol) of 3-chloro4-cyanc-4-trimethylsilyloxy-4H-2,3-dihydrobenzopyranne of 3 ml of concentrated hydrochloric acid. The mixture never becomes homogeneous even after being kept for 23 hours at 200C. It is diluted with 30 ml of water and as much ethyl acetate. The organic phase is washed twice with 50 ml of saturated sodium chloride, it is dried over magnesium sulphate, filtered and evaporates it under vacuum to obtain a residue which, after trituration with methylene chloride, gives 0.606 g (54%) of 6-chloro-4-hydroxy-4H2,3-dihydrobenzopyranne-4-carhoxamide melting at 168-169 C .

Rf = 0.18 (chloroform: 1: 1 ethyl acetate, silicic acid).

EXAMPLE 9 6-chloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] 2'4,' - dione
0.101 g (4.40 gram-atoms) of sodium is reacted with 3.34 g (44.0 mmol) of n-butanol and Q, 545 g (4.62 mmol) of diethyl carbonate. When the evolution of hydrogen has ceased, 1.00 g (4.40 mmol) of 6-chloro 4-hydroxy-4H-2,3-dihydrobenzopyranne-4-carboxamide is added and the mixture is heated at 1150C for 3 days . By adding another 0.545 g (4.62 mmol) of diethyl carbonate and 0.100 g (0.89 mmol) of potassium tert-butoxide (Aldrich) while heating for a further 4 days, the total reaction is obtained. The cooled mixture is poured onto 100 ml of ice-cold IN hydrochloric acid. The aqueous phase is extracted twice with 100 ml of ethyl acetate. The combined organic phases are extracted twice with 50 ml of 5% sodium bicarbonate.

The basic phase is acidified by addition of 6N hydrochloric acid and extracted twice with 100 ml of ethyl acetate. This organic phase is dried over magnesium sulfate, filtered and evaporated in vacuo to give a solid substance. By recrystallization from toluene, 0.299 g is obtained (27% of 6 - chloro-spiro [4H-2,3-dihydrobenzopyranne (4.5 ') - oxazolidine] -2', 4'-dione melting at 190-1930C .

NO d' R1 R2 R3 X Durée Rende- Rf (solvant) exemple 1 2 3 réact. ment (%) 10 Br H H O 16 h Quanti- 0,90 (éther
tatif diéthylique) 11 F H H O 16 h 99 0,79 (éther di éthylique) 12 C1 H C1 O 72 h 89 0,90 (acétate
éthylique)
(P.F.68-71 C) 13 Cl H CH3 O 24 h 58* 0,90 (acétate 14 F H H S 18 h Quanti- éthylique)
tatif 15 Cl H H S 72 h 98,6 0,89 (éther diéthy
lique:pentane) 16 H H H S 72 h 99 0777~(éther diéthy
lique:pentane) 17 H H H O 18 h Quanti-
tatif
* yaleur déterminée par résonance magnétique nucléaire.EXAMPLES 10 to 17
Following the procedure of Example 1, the following compounds are prepared, replacing 6-chloro4H-2,3-dihydrobenzopyranne-4-one with the ketones suitably chosen. All the compounds are isolated in the form of oils after washing with 5% sodium bicarbonate and brine then dehydration over magnesium sulfate followed by evaporation under vacuum. The characterization is carried out by nuclear magnetic resonance and / or by thin layer chromatography of silicic acid.

NO of R1 R2 R3 X Duration Rende- Rf (solvent) example 1 2 3 react. ment (%) 10 Br HHO 16 h Quanti- 0.90 (ether
diethyl tative) 11 FHHO 16 h 99 0.79 (diethyl ether) 12 C1 H C1 O 72 h 89 0.90 (acetate
ethyl)
(PF68-71 C) 13 Cl H CH3 O 24 h 58 * 0.90 (acetate 14 FHHS 18 h Quantiethyl)
tative 15 Cl HHS 72 h 98.6 0.89 (diethyl ether
lique: pentane) 16 HHHS 72 h 99 0777 ~ (diethyl ether
pic: pentane) 5 p.m. HOH 6 p.m. Quanti-
tative
* value determined by nuclear magnetic resonance.

EXAMPLE 18-23
By following the procedure of Example 2, the following compounds are prepared by using the corresponding reactants in place of 6-chloro-4-cyano4-trimethylsilyloxy-4H-2,3-dihydrobenzopyranne, but by adopting the next modified processing. The crude mixture is partitioned between water and ethyl acetate and the phases are separated. The aqueous phase is made basic at pH-12 by addition of 6N sodium hydroxide and extracted with ethyl acetate. The organic phase is washed with. the brine, dehydrated over magnesium sulfate, filtered and evaporated in vacuo to give the solid imidates.

Example R1 R2 R3 X Reaction Yield P.F.

No. (bubbling) (%)
18 FHHO 4 ha (30 min) 69 118.5-120
19 Br HHO 18 ha (20 min) 23 117-122
20 HHHS 18 hb (15 min) 65 145-147 @@ FH 4 S 18 h 15 min) ~ 44 139-140.5
(ether
diethyli
que-hexane)
H Cl O 48 b (30 min) 59 125.5-129
(hexane)
@ HO i8 hb (30 min) 86 98-101 a) mixture kept at room temperature (20 C) b) mixture refrigerated at @ C.

Following the procedure of Example 8, the following compounds are prepared using the corresponding reactants in place of 6-chloro-4-cyano4-trimethylsilyloxy-4H-2,3-dihydrobenzopyran.

Example R1 R2 R3 X Render Duration
No. 3 bubbling ment (%) PF

24 Cl H CH3 O 1 min 37 157-1590C 25 Cl H Cl O 10 min 83 200-200.5 C 26 Cl HHS 60 min 68 121-123 C
EXAMPLE 27
Spiro [4H-2,3-dihydrobenzopyran (4,5 ') oxazolidine] -2', 4'dione
Saturated with gaseous phosgene for 30 minutes, a mixture of 5.50 g (24.9 mmol) of ethyl 4-hydroxy-4H-2,3-dihydrobenzopyranne-4-carboximidate and 5.03 g (49, 7 mmol) of triethylamine in 50 ml of 0 tetrahydrofuran. A solid substance forms immediately during the bubbling. The mixture is stirred for 16 hours at 20 C. Under these conditions, the oxazolidine-dione is obtained directly without isolation or hydrolysis of the intermediate oxazoline. The reaction mixture is poured onto 200 ml of crushed ice and it is extracted with 1 ml. 'ethyl acetate. The spiro- [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] 2', 4'-dione is isolated from this organic phase by the operations described in Example 3 in a yield of 56.7%; this compound melts at 168-170 C.

EXAMPLE 28 6-fluoro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] -2', 4'-dione
6-fluoro-spiro-4H-2,3-dihydrobenzopyran (4,5 ') oxazolidine-2', 4'-dione is prepared as described in Example 4 from 6-fluoro-4-hydroxy -4H-2,3dihydrobenzopyran-4-ethyl carboximidate in a yield of 48%, but the mixture is heated at 1000C for 1.0 hour; the compound melts at 177.5-1800C after recrystallization from toluene.

EXAMPLE 29 6-bromo-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] 2', 4'-dione
6-bromo-spiro [4H-2,3-dihydrobenzopyran (4,5 ') oxazolidine] -2', 4'-dione is prepared as described in Example 4 starting from 6-bromo-4- hydroxy-4H-2,3dihydrobenzopyran-4-ethyl carboximidate in a yield of 38%, but the mixture is heated at 100 ° C. for 0.5 hour; the compound melts at 188-1910C after recrystallization from toluene.

EXAMPLE 30
Spiro C4H-2,, 3-dihydrobenzothiopyran (4,5 ') oxazolidine] -2', 4'-dione
Spiro [4H-2,3-dihydrobenzothiopyranne (4,5 ') oxazolidine] -2', 4'-dione is prepared as described in Example 4 from 4-hydroxy-4H-2,3 dihydrobenzothiopyranne -4-ethyl carboxmidate in a yield of 45%, but the mixture is heated at 1000C for 7.0 hours t the compound melts at 165-1670C after recrystallization from toluene.

EXAMPLE 31 6-fluoro-spiro [4H-2,3-dihydrobenzothiopyranne (4,5 ') oxazolidi ne 12', 4 '-dione
6-fluoro-spiro [4H-2,3-dihydrobenzothiopyran (4,5 ') - oxazolidine] -2', 4'-dione is prepared as described in Example 4 from 6-fluoro-4 -hydroxy-4H2,3-dihydrobenzothiopyranne-4-carboximidate ethyl in a yield of 41%, but the mixture is heated at 1000C for 48 hours; the compound melts at 193-194.50C after recrystallization from toluene.

EXAMPLE 32 6,8-dichloro-spiro [4H-2,3-dihydrobenzopyran (4,5 ') oxazoli ne 1-2', 4'-dione
A mixture of 524 mg (2.00 mmol) of 6,8-dichloro-4-hydroxy-4-carboxamide, 531 mg (4.5 mmol) of ethyl carbonate, 396 mg, is refluxed for 64 hours. (2.67 mmol) of potassium tert-butoxide (Aldrich) and 1.80 ml of n-butanol. The reaction mixture is quenched with 100 ml of normal sulfuric acid and 100 ml of ethyl acetate. The aqueous phase is washed with another 100 ml of ethyl acetate and the combined organic phases are then extracted, two. times with 50 ml of 5 t sodium bicarbonate. The basic phase is acidified with 6N hydrochloric acid and extracted twice with 75 ml of ethyl acetate. The last two organic phases. collected are washed with 50 ml of brine, dried over magnesium sulfate, filtered and evaporated under vacuum into a solid substance weighing 330 mg (yield 57%).

By recrystallization of this substance in toluene, 6,8-dichloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') - oxazolidine-2', 4'-dione melting at 193-1950C is obtained.

EXAMPLE 33 6-chloro-8-methyl-spirof4E-2,3-dihydrobenzopyranne (4,5'l- oxazolidine] -2 ', 4'-dione
6-chloro-8-methyl-spiro [4H-2,3-dihydro-benzopyran (4,5 ') - oxazolidine] -2', 4'-dione is prepared as described according to Example 32 from 6-chloro-8-methyl4-hydroxy-4H-2,3-dihydrobenzopyranne-4-carboxamide, in a yield of 21.6%; the compound melts at 185.5-187 C after recrystallization from toluene.

EXAMPLE 34 6-chloro-spiro [4H-2,3-dihydrobenzothiopyran (4,5 ') oxazolidinei-2', 4'-dione
6-chloro-spiro [4H-2,3-dihydrobenzothiopyran (4,5 ') oxazolidine] -2', 4'-dione is prepared as described in Example 32 from 6-chloro-4- hydro-4H-2,3-benzothiopyranne-4-carboxamide in a yield of 38, but the reaction mixture is heated at reflux for 54 hours. The compound melts at 213-2160C after recrystallization from toluene.

EXAMPLE 35 (-) - 6-chloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') oxazolidine] --2', 4'-dione
Dissolved by heating 32.0 g (0.125 mol) of 6 chloro-spiro- [4H-2,3-dihydrobenzopyranne (4.5l) -oxazolidine] -2 ', 4'-dione racemic and 37.1 g (0.126 mole) of cinchonidine in 290 ml of anhydrous etharol. After cooling, 28.0 g (81%) of a solid which is the product of the addition of (+) oxazolidine-dione and cinchonidine are collected by filtration. The filtrate is concentrated under vacuum to obtain a residue which is partitioned between 500 ml of ethyl acetate and 400 ml of 1N hydrochloric acid. The organic phase is washed with an additional 400 ml of 1N hydrochloric acid and 200 ml of brine, dried over magnesium sulfate, filtered and concentrated to a volume of 150 ml. 10.13 g (0.075 mole) of liquid L-amphetamine are added to this organic solution. The dense precipitate which then forms is filtered, washed with ether and dried under vacuum, giving 14.85 g (60%) of product. addition of (-) - oxazolidine-dione and of amphetamine of optical rotation [α] EtOH equal to -36.29; melting point 171-174 C. This adduct (14.80 g) is divided between 300 ml of ethyl acetate and 200 ml of hydrochloric acid @N. The organic phase is washed with an addition amount of 200 ml of hydrochloric acid @@ and @@@ ml of @@ mm @@@ @@@ it is dried over sulf @@@ @@@ @@ @@@@@@ @@@@ and evaporated under vacuum to give a colorless solid (yield @@, @ @@@@@@@@@@ @@@ 201-202.5 C. By
@ oristel @@ sation in @@ toluene, we obtain 8.203 g of (-) - @@@@@@@@@@@@@@@@@@ hydrobenzopyranne- (4,5 ') - oxazolidine] - @ @ @ -dione fond @@@ at 200-200.5 C; [α] EtOH = -61.59.

EXAMPLE 36 @@@@ enement of 6-chloro-spiro [4H-2,3-dihydrobenzopyranne- (4,5 ') - oxazolidine] -2', 4'-dione
1.00 g (3.95 mmol) of 6-chloro-spiro [4H-2,3-dihydrobenzopyr exazolidine] -2 ', 4'-dione and 1.16 g (3, 4) are dissolved in hot ethanol. 95 mmol) of cinchonidine. When the adduct has precipitated, it is collected and it is recrystallized from ethanol; it melts at 206-207 C. This solid substance is partitioned between 50 ml of ethyl acetate and as much 1N hydrochloric acid. The acid phase is extracted with 50 ml of ethyl acetate The combined organic phases are washed with 50 ml of brine, dried over magnesium sulfate, filtered and evaporated in vacuo to give a residue which is recrystallized from. toluene; 288 mg (57%),
PF = 193-1970C. By recrystallization of this compound from toluene, 200 mg (40%) of (+) - 6-chloro-spiro [4H-2,3-dihydrobenzopyran (4.5 ') - oxazolidine] -2', 4 'are obtained. -dione melting at 200-201.5 C; [α] EtOH = (+) 60.55.

From the first ethanolic mother liquor, a small quantity of crystals of the positive isomer of the adduct is obtained in second harvest, after standing for approximately 18 hours. After filtration, this mother liquor is partitioned between 50 ml of 1N hydrochloric acid and as much ethyl acetate. The oxazolidine-dione obtained as indicated above is recycled twice into toluene, giving 143 mg (29%) of 6-chlorospiro [4H-2,3-dihydrobenzopyran (4.5 ') oxazolidine] - 2 ', 4' dione melting at 199-200 C; [α] EtOH = (-) 61.72.

EXAMPLE 37
Duplication of 6-chloro-spiro [4H-2,3-dihydrobenzopyranne (4,5 ') - oxazolidine] -2', 4'-dione
1.00 g (3.95 mmol of 6-chloro-spiro [4H-2,3-dihydrobenzopyran (4.5 ') - oxazolidine] -2', 4'-dione and 264 mg (2.00 mmol) are dissolved. ) of L-amphetamine in hot ethyl acetate. The dried crystals and collected after cooling (419 mg, PF 165-168 C) are recrystallized from ethyl acetate, 221 mg of compound is obtained at 171 -173 C; [α] EtOH = (-) 32.7. The cleavage of the adduct and the isolation of (-) oxazolidine-dione are carried out as described in Example 33; 53 mg of fluxing compound
EtOH at l98-200 C; Lai D @@@@@
EXAMPLE 38
Spiro-oxazolidine-diones prepared as described in the examples above were tested for their ability to reduce or inhibit the enzymatic activity of aldose reductase, according to the method described in the U.S. Patent No. 3,821,383, cited above, and based on the method described by
Hayman et al. In "Journal of Biological
Chemistry ", 24u, 877 (1965). The substrate used is the partially purified aldose reductase extracted from the calf lens. The results obtained with each compound at a concentration of 10 M are expressed by the percentage inhibition of l enzyme activity.

Example No. Percentage inhibition
of the compound at the concentration of 10-6M
86768
3
65
28 100/8?
29
42
30
61
31
100
32
81/99
33
34 70/100
35 96 (A slash between two values corresponds to tests carried out in duplicate
EXAMPLE 39
Spiro-oxazolidine-diones prepared in the manner described in the above examples were tested for their ability to reduce or inhibit the accumulation of sorbitol in the sciatic nerve of rats treated with streptozotocin (this is that is to say diabetics) essentially following the method described in the aforementioned US Patent 3,821,383.

In this study, the amount of sorbitol accumulated in the sciatic nerves was measured 27 hours after the onset of diabetes. The compounds were administered orally at the doses indicated, 4, 8 and 24 hours after the administration of streptozotocin. The results obtained in this way are reproduced below and expressed by the percentage of inhibition offered by the test compound compared to the case where no compound has been administered (i.e. the animal untreated with sorbitol levels normally ranging from about 50-100 mM / g of tissue to up to 400 St / g of tissue in the 27 hour test period).

In this test, values lower than 20 do not always have an experimental and statistical significance.

Example N Percentage inhibition of the compound at the dose indicated in mg / kg
1.5 5 15
3 28 -
28 8 -
29 35 -
32 44 -
33 33 -
34 14 -
35 41 67 88

Claims (1)

CLAIM Compound characterized in that it corresponds to the formula

in which X is an oxygen or sulfur atom n is equal to 1 or 2; R1, R2 and R3 each represent a hydroene atom or a chloro, bromo, fluoro, alkyl radical having 1 to 3 carbon atoms, phenyl or monosubstituted phenyl whose substituent is a chloro, bromo, fluoro, hydroxyl, alkyl radical having 1 to 3 carbon atoms or alkoxy having 1 to 3 carbon atoms and R4 is an alkyl group having 1 to 4 carbon atoms, benzyl or monosubstituted benzyl, the substituent of which is a chloro, bromo, fluoro, hydroxy, alkyl radical having 1 to 3 carbon atoms or alkoxy having 1 to 3 carbon atoms.