CA1292992C - Spiro-heteroazolones for treatment of diabetes complications - Google Patents

Abstract

Abstract Spiro-heteroazolones of the formula below are disclosed which are useful as aldose reductase inhibitors and as therapeutic agents for the treat-ment of complications arising from diabetes:

I

or a pharmaceutically acceptable salt thereof, wherein A is methylene, hydroxy-methylene, or methine; Y is methylene, alkylmethylene, methine or alkyl-methine, wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when A is methine, Y is methine or alkylmethine; Z is oxygen, sulfur, or nitrogen substituted by hydrogen; Q is nitrogen or nitrogen-N-oxide; and X is in the 3'-position and is hydrogen, halo, alkyl, alkoxy having 1-4 carbon atoms, alkylthio, alkylsulfinyl, alkylsulfonyl, phenoxy, phenylthio, or nitro;
or X is in the 2'-position and is hydrogen, alkyl, or alkoxy having 1-4 carbon atoms; wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when Q is nitrogen-N-oxide, X is not alkylthio, alkylsulfinyl or phenylthio; and with the further proviso that when Q is nitrogen and X is hydrogen and Z is nitrogen substituted by hydrogen, at least one of A and Y is always other than methylene.

Description

9~

P.C. 6849 SPIRO-HETEROAZOLONES FOR TREATMENT
OF DIARETIC CO~PLICATIONS

This invention relates to novel ~eirQ-heteroazolones useful in the treatment of certain chronic complications arising from diabetes mellitus, such as diabetic cataracts, retinopathy and neuropathy, to pharmaceutical compositions containing such compounds and to a method of using these compounds.
In the past, various attempts have been made to obtain more effective oral anti-diabetic agents.
Generally, these efforts have involved synthesis of new organic compounds, particularly sulfonylureas, and determination of their ability to substantially lower blood sugar levels when administered orally. However, little is known about the effect of organic compounds in preventing or alleviating chronic complications of diabetes, such as diabetic cataracts, neuropathy and retinopathy. U.S. Patent No. 3,821,383 discloses aldose reductase inhibitors like 1,3-dioxo-lH-benz[d,e]-isoquinoline-2(3H)-acetic acid and derivatives thereof to be useful for the treatment of these conditions. U.S.
Patent No. 4,117,230 teaches the use of certain hydantoins for treating complications of diabetes as aldose reductase inhibitors. Such aldose reductase inhibitors function by inhibiting the activity of the enzyme aldose reductase, which is primarily responsible for regulating the reduction of aldoses, such as glucose and galactose, to the corre-sponding polyols, such as sorbitol and galactitol, in humans and other animals. In this way, unwanted accumulations of galactitol in the ~ens of galactosemic ~k - 1292~9Z

subjects and of sorbitol in the lens, peripheral nervous cord and k~idneys of various diabetic subjects are prevented or reduced. Accordingly, such compounds are of therapeutic value as aldose reductase inhibitors for controlling certain chronic diabetic complications, including those of an ocular nature, since it is known in the art that the presence of polyols in the lens of the eye leads to cataract formation, with a concomitant loss of lens clarity.
Carr et al., U.S. Patent No. 3,985,888, t~ach certain spiroalkanone-imides and their use as sedatives.
European Patent Application Publication No. 0065392 discloses certain sPiro-succinimide derivatives and their use as aldose reductase inhibitors.
The compounds of the present invention are spiro-heteroazolones of the formula:

NH

~ ---I

or a pharmaceutically acceptable salt thereof, wherein A is methylene, hydroxymethylene, or methine;
Y is methylene, alkylmethylene, methine or alk~ylmethine, wherein alk~l in each instance has 1-4 carbon atoms; with the proviso that when A is methine, Y is methine or alkylmethine; Z i5 oxygen, sulfur or 1~9Z~92 nitrogen substituted by hydrogen; Q is nitrogen or nitrogen-N-oxide; and X
is in the 3'-position and is hydrogen, halo, alkyl, alkoxy having 1-4 carbon atoms, alkylthio, alkylsulfinyl, alkylsulfonyl, phenoxy, phenylthio, or nitro;
or X is in the 2'-position and is hydrogen, alkyl or alkoxy having 1-4 carbon atoms; wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when Q is nitrogen-N-oxide, X is not alkylthio, alkylsulfinyl or phenyl-thio; and with the further proviso that when Q is nitrogen and v is hydrogen and Z is nitrogen substituted by hydrogen, at least one of A and Y is always other than methylene.
Preferred compounds include those wherein Z is nitrogen substituted by hydrogen, and Q is nitrogen or nitrogen-il-oxide. Further preferred are com~ounds wherein Y is methylmethylene, A is methylene or hydroxymethylene and ,. is hydrogen or chloro. Also preferred are compounds wherein A is methine, Y i~ methylmethine and X is hydrogen.
Both mixtures of optically active isomers and partially or complete-ly optically resolved isomers of the compounds claimed herein are within the scope of the present invention.
The present invention also provides a process for producing a com-pound of formula I or a pharmaceutically acceptable salt thereof. The process comprises:
(a) condensing an appropriately substituted carbonyl ring compound of the formula:

X ~ ~ IV
N R

~ 3a _ 1Z9Z992 wherein X is as previously defined and R is hydrogen or alkyl having 1-4 carbon atoms, with an alkali metal cyanide and ammonium carbonate to form the corresponding ~ hydantoin final product of the formula:

~ NH
zJ~o X ~ IA
R

wherein Z is nitrogen substituted by hydrogen and X and R are each as previous-ly defined; or (b) reacting a compound of formula IV as defined above with a tri-alkylsilyl cyanide (wherein each alkyl has 1-4 carbon atoms) in the presence of a Lewis acid to produce a corresponding cyano trialkylsilyloxy derivative, then reacting the cyano trialkyl~llyloxy derivative with an acid to convert it into an alkyl-hydroxycarboximidate derivative, and finally converting the alkyl-hydroxycarboximidate into a spiro-oxazolidin-2,5-dione of formula IA
as defined above (wherein Z iB oxygen, or sulfur); and (c) when required, oxidizing a compound of the formula IA wherein Z
is as originally defined and X is not alkylthio, alkylsulfinyl or phenylthio to a corresponding compound of the formula:
O ~ NH

~ \ O IB

N R
o wherein X, Z and R are each as previously defined except that X is not alkyl-thio, alkylsulfinyl or phenylthio; and - 3b - 1Z~2992 (d) when required, transforming a compound of the formula IB into a compound of the formulae:

O O
~ IH \l ~a X ~ or IC ID
wherein X, Z and ~ are each as previously defined, except that X is not alkyl-thio, alkylsulfinyl or phenylthio, by reacting the formula IB compound with acetic anhydride in an acidic medium, followed by hydrolysis of the resulting acetate salt in an aqueous solvent at a pH of at least about pH 10;
and thereafter, if desired, con~erting a compound of formula IA, IB, IC or ID to a pharmaceutically acceptable salt thereof, whereby a spiro-heteroazolone compound of formula I or a pharmaceutically salt thereof is ob-tained.
The numbering system of the spiro-compounds of formula I is as shown.

12gZ99Z

~ 2 4' Z ~ O
X ~
2' 1 8'~

The compounds are spiro[imidazolidine, oxazolidine or thiazolidine-4,5'(6'H)-quinoline or quinoline-N-oxide ]-2,5-dione~s. The compounds can be substituted by X in the 2'- or 3'-positions and can be 7',8'-dihydro derivatives.
Diastereomers can be separated by methods known in the art, such a3 recry3tallization with a suitable solvent like isopropanol, or trituration, for example, with an alcohol-ether solvent such as isopropanol-diethyl ether. The term~ "Rel" and "(~)" each mean a 1:1 racemic mixture of the two optically active enantiomers.
When X is halo, halo includes fluoro, chloro, bromo and iodo.
In the Synthetic Scheme a preparation of compounds of formula I is shown. Compounds of for~ulae I.~-D are subclasses of compounds of formula I and are within the scope of the present invention. Starting diketone II
wherein R is hydrogen or alkyl having 1-4 carbon atoms is reacted with ammonia in a refluxing solvent, such as benzene, which will remove the water of reaction as an azeotrope to obtain ketone eneamine III. When X is hydrogen, III is reacted with propynal in a polar aprotic organic solvent such as dimethylformamide at an initial 12~?Z39Z

temperature of between about -10 and 25C, preferably about 0C, followed by a period of heating of between about 15 and 90 minutes, preferably about 45 minutes, at a temperature of between about 100 and 153C, preferably about 153C, to obtain tetrahydroquinoline derivative IV where X is hydrogen.
When X is other than hydrogen, alkene aldehyde, V
or VI, -~hich are known compounds or can be prepared analogously to the known compounds, is reacted with ketone eneamine III in a polar, aprotic organic solvent such as dimethylformamide at between about -10 and 25C, followed by heating at between about 100 and 153C, to obtain tetrahydroquinoline derivative IV.

129Z~92 =~ H H
x T

H

31 -~

o~ _ EO =~> X

~Z~

~C --O ~ j H >,=/

_7_ 1~2~92 ~ ~Z-O
~ X
~ / ~
u u H
E~
z V~

l~Z'r392 ,0 ~

H
-C
O
O
~ ~ +
~ P::
U~

~ ~ , .
I L'~ ~
x H

9 ~ 92 ~
+

~:C ) H

When 2 is nitrogen substituted with hydrogen, the compound of formula IV can be reacted to obtain the corresponding compounds of formula IA, for example, by means of the methods described in U.S.
Patent Mo. 4,117,230. A compound of formula IV is condensed with an alkali metal cyanide (e.g., sodium cyanide or potassium cyanide) and ammonium carbonate to form the desired sPiro-hydantoin final product.
This reaction is normally carried out in the presence 10 of a reaction-inert polar organic solvent medium in which both the reactants and reagents are mutually miscible. Preferred organic solvents include cyclic ethers such as dioxane and tetrahydrofuran, lower alkylene glycols like ethylene glycol and trimethyl-15 ene glycol, water-miscible lower alkanols such as methanol, ethanol and isopropanol, as well as N,N-di(lower alkyl) lower alk,anoamides like N,~J-dimethyl-formamide, ~,N-diethylformamide and N,N-dimethyl-acetamide, etc. In general, the reaction is conducted 20 at a temperature that is in the range of from about 20C. up to about 120C. for a period of about two hours to about four days. Although the amount of reactant and reagents employed in the reaction can vary to some extent, it is preferable to employ at 25 least a siight molar excess of the alkali metal cyanide reagent with respect to the carbonyl ring compound starting material in order to effect maximum yield.
Upon completion of the reaction, the desired product is easily isolated in a conventional manner, e.g., 30 by first diluting the reaction mixture with water (boiling if necessary) and then cooling the resultant aqueous solution to room temperature, followed by acidification to afford the sPiro-hydantoin compound in the form of a readily-recoverable precipitate.

- lZ92~3~Z

When X is 2'-alkoxy, the preferred method of pre-paring the corresponding compounds of formula I is according to the procedure of Dubas-Sluyter et al., Recueil Chim Pays Bas, 91, 157-160 tl972) wherein a compound of formula III is reacted with an alkyl propiolate VIII wherein Rl is alkyl having 1-4 carbon atoms, preferably methyl, in a polar aprotic solvent such as dimethylformamide or carbitol at a temperature range of between about 100 and 153C., preferably about 153C., to obtain the hydroxy compound of formula IVA. It is to be understood that the compound of IVA may also be present as the 2-pyridone isomer.
The compound of formula IVA is reacted with an a water soluble inorganic silver salt such as silver nitrate and aqueous base such as potassium hydroxide at a pH of between about 9 and 12, preferably about 10.5, and at a temperature o between about 0 and 6noc, preferably about 25C, to form a silver salt. The isolated silver salt is reacted with an alkyl iodide of the formula R2-I wherein R2 is alkyl having 1-4 carbon atoms at a temperature of between about 25 and 100C, preferably 60C, to obtain the 2-alkoxy quinoline derivative IVB. The conversion to compounds of formula I continues according to the procedures set forth for a compound of formula IV.
When Z is oxygen, the compound of formula IV can be reacted to obtain the corresponding compounds of formula IA by means of the methods described, for example, in U.S. Patent Nos. 4,226,875 and 4,267,342. In one procedure, a compound of formula IV is reacted with a trialkylsilyl cyanide, wherein each alkyl has 1-4 carbon atoms and is preferably methyl, to form the corresponding cyano trialkylsilyloxy derivative. The reaction is conducted in the presence of a Lewis acid lZ9Z~9Z

catalyst, such as a zinc halide, aluminum halide or boron trifluoride, with zinc iodide being a preferred catalyst. Temperatures in the range of about 0 C. to about 50C. are generally employed, preferably about o C. to 20C., in an inert organic solvent, typically an ether such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxane and the like, or a halohydro-carbon such as methylene chloride, chloroform and similar solvents. The resulting cyano trialk~lsilyloxy derivative is then converted to an alk~yl-hydroxy-carboximidate derivative by reaction with an acid in an alcohol solvent R40H. Suitable acids include hydrogen halides, especially hydrogen chloride. The alcohol R40H may be either a lower alkanol of 1 to 4 carbon atoms, benzyl alcohol or a substituted benzyl alcohol, the substituent including chloro, bromo, fluoro, hydroxy, alk~l of 1 to 3 carbon atoms and alkoxy of 1 to 3 carbon atoms. The reaction is generally conducted at temperatures in the range of about -10C. to about 25C., preferably at about 0C.
to 10C.
The hydroxy carboximidate derivative may be converted directly to the desired sPiro-oxazolidin-2,5-dione I~ by a number of methods. In all cases, a ~
4-alkoxy-oxazolin-2-one is an intermediate and can, if desired, be isolated from the reaction mixture. However, it is generally preferred to convert directly without such isolation of the intermediate. The hydroxy carboximidate may be reacted with phosgene in the presence of a base such as triethylamine, or other tri-alkylamines having from 1 to 4 carbon atoms in each alkyl group, in an inert organic solvent such as an ether, for example, diethyl ether, tetrahydrofuran, --``` lZ92992 dimethoxyethane, dioxane and the like. The phosgene is generally bubbled through the reaction solution at a temperature of about -10C. to about 10C., for about 5 to 15 minutes and the solution is subsequently stirred at about 20C. to 50C., preferably at about 25C., for about 12 to 48 hours, when the sPiro-oxazolin-2-one is predominantly formed. This intermediate may then be converted to the desired spiro-oxazolidin-2,5-dione IA either by a further perfusion of phosgene at about -10C. to about 10C. for about 15 to 75 minutes, followed by stirring at room temperature for a further period of about 12 to 48 hours. Alternatively, an alkali metal carbonate, such as potassium or sodium carbonate, or ammonium carbonate can be added to a solution of the intermediate in, for example, aqueous tetrahydrofuran, and stirred at a temperature of about 15C. to about 50C., preferably at about 25C.~for a period of about 6 to 24 hours to form the desired s~iro-oxazolidin-2,5-dione IA.
The desired spiro-oxazolidin-2,5-dione IA can also be prepared from the hydroxy carboximidate derivative by reaction with an alkyl haloformate, where the alk~l group is of 1 to 4 carbon atoms, a preferred re-aaent being ethyl chloroformate. The reaction is generally conducted by stirring the hydroxy carboximidate intermediate together with the alkyl haloformate in an inert solvent, such as pyridine, at a temperature of about -10C. to about 15C., preferably at about 0C., for a period of 30 minutes to about 2 hours, followed by heating the solution to a higher temperature, about 50C. to about 150C., preferably about 90C. to 120C., for example,to reflux temperature in pyridine, for about 2 to about 6 hours. If desired, the sPiro-oxazolidin-2-one intermediate can be isolated from the initial reaction mixture after heating the solution for relatively shorter periods, for example,about 1 hour.
The spiro-oxazolidin-2,5-diones can also be prepared from the hydroxy carboximidate derivative by reaction with l,l'-carbonyl-diimidazole, the reaction being generally conducted at a temperature of about 50C. to 150C., preferably about 80C. to 110C., neat or in an inert organic solvent such as dioxane, tetrahydrofuran, dimethoxyethane, diethyl ether and the like, for a period of about 12 to 36 hours. If desired, the intermediate spiro-oxazolin-2-one can be obtained by heating for only a relatively short period of time, for example,about 30 minutes to about 90 minutes.
When Z is sulfur, the compounds of formula IA
can be prepared by tak~ing advantage of the hydroxy carboximid~te derivatives previously discussed.
These are converted to chlorocarboximidate derivatives by heating with thionyl chloride at between about 35C
and the reflux temperature of about 79C for 1-3 hours, preferably about 2 hours The resulting chlorocarboximate derivatives are reacted with thiourea in a refluxing alkanol of 1-4 carbons, preferably ethanol, or about 15-90 minutes, preferably 30 minutes, followed by a brief aqueous hydrolysis either during column chro-matography on acidic silica gel, or in aqueous tetra-hydrofuran or dioxane containing about 0.1 to 6N
hydrochloric acid at about 0-60C., preferably about 25C.

~z~9z ~he compound of formula IA can be oxidized to the compound of formula IB wherein Q is nitrogen -N-oxide by any procedure known in the art. In one procedure about 30 percent by volume aqueous hydrogen peroxide in an acidic solvent such as acetic acid at a temperature of between about 0 and 100C., preferably about 85C. This oxidation procedure should be avoided when X is alkylthio, alkylsulfinyl or phenylthio in order to prevent oxidation of the sulfur moiety on X.
The compound of formula IB can be transformed into a compound of formula IC or ID by the reaction with acetic anhydride in acetic acid or neat con-taining a trace of water at a temperature range of between about 60 and 95C., preferably about 95C.
~.he resulting acetate salt VII is reacted at about 0-60C,, preferably about 25C., in an aqueous solvent such as water,aqueous tetra-hydrofuran or aqueous dioxane at a pH of between about 10 and 14, preferably about 13, to obtain IC
and ID. The relative amounts formed of these product in the basic aqueous solution depends upon the reaction temperature, pH and nature of the R substituent Because of the acidic hydrogen atom in the spiro-5-membered heterocyclic ring of the compounds of formula I, salts may be formed with pharmaceutically acceptable cations by conventional methods. Thus, these salts may be readily prepared by treating the compound of formula I with an aqueous solution of the desired pharmaceutically acceptable cation and evaporating the resulting solution to dryness, preferably under reduced pressure. Alterna-tively, a lower alkyl alcohol solution of the -= 1292~92 compound of formula I may be mixed with an alkoxide of the desired cation and the resulting solution sub-sequently evaporated to dryness. Suitable pharmaceuti-cally acceptable cations for this purpose include, but are not limited to, alkali metal cations such as potassium and sodium, alkaline earth metal cations such as calcium and magnesium, ammonium, lower alkanol-ammonium and other cations derived from pharmaceutically acceptable organic amines which can form water-soluble amine addition salts.
Acid addition salts can be formed for compounds of formula I when Q is nitrogen. Suitable salts include those derived from hydrochloric acid, sulfuric acid or methylsulfonic acid. These acid addition salts can be prepared by the addition of the appropriate strong acid to a lower alcoholic solution of a compound of formula I at a temperature of 0-60C,, preferably 25C., followed by concentration to obtain the desired product.
Alternatively, an aqueous slurry of a compound of formula I can be mixed with the appropriate strong acid at about 0-60C., preferably about 25C,, followed by freeze drying and recrystal-lization from a lower alcohol.
Pharmaceutically acceptable salts are those which do not cause unacceptable adverse reactions when administered.
The novel compounds of formula I and the pharmaceutically acceptable salts thereof are useful as inhibitors of the enzyme aldose reductase in the treatment of chronic complications of diabetes, such as diabetic cataracts, retinopathy and neuropathy.
As used in the claims and specification hereof, treatment is meant to include both the prevention and alleviation of such conditions. The ~Z~2~'~2 compound may be administered to a subject in need of treatment by a variety of conventional routes of administration, including orally, parenterally and topically.
In general, these compounds will be administered orally or parenterally at dosages between about 0.05 and 25 mg./kg. body weight of the subject to be treated per day, preferably from about 0.1 to 10 mg./kg. per day. However, some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject.
The novel compounds of the invention may be admin-istered alone or in combination with pharmaceutically acceptable carriers, in either single or multiple doses. Suitable pharmaceutical carriers include inert solid diluents or fillers, sterile aqueous solutions and variou~ organic solvents. The pharmaceutical compo~ition~ formed by combining the novel compounds of formula I and the pharmaceutically acceptable 20 carrier~ are then readily administered in a variety of dosage forms such as tablets, powders, lozenges, syrups, injectable solutions and the like. These pharmaceutical compositions can, if desired, contain additional ingredients such as flavorings, binders, 25 excipients and the like. Thus, for purposes of oral administration, tablets containing various excipients such as sodium citrate, calcium carbonate and calcium phosphate may be employed along with various dis-integrants such as starch, alginic acid and certain 30 complex silicates, together with binding agents such as polyvinylpyrrolidone, sucrose, gelatin and acacia.
Additionally, lubricating agents such as magnesium stearate, soaium lauryl sulfate and talc are often 12~2~92 useful for tabletting purposes. Solid compositions of a similar type may also be employed as fillers in soft and hard filled gelatin capsules. Preferred ~aterials for this include lactosc or milk~sugar and high molecular weight polyethylene glycols. When aqueous suspensions or elixirs are desired for oral administration, the essential active ingredient therein may be combined with various sweetening or flavoring agents, coloring matter or dyes and, if desired, emulsifying or suspending agents, together with diluents such as water, ethanol, propylene glycol, glycerin and combinations thereof.
For parenteral administration, solutions of the novel compound of formula I in sesame or peanut oil, aqueous propylene glycol, or in sterile aqueous solution may be employed. Such aqueous solutions should be suitably buffered if necessary and the liquid diluent irst render~d isotonic with suficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. In this connection, the sterile aqueous media employed are all readily available by standard techniques known to those skilled in the art.
Compounds of formula I may not only be advantageously employed for the preparation of aqueous pharmaceutical compositions for parenteral administration, as described above, but more particularly for the preparation of pharmaceutical compositions suitable for use as ophthalmic solutions. Such ophthalmic solutions are of principal interest for the treatment of diabetic cataracts by topical administration and the treatment of such conditions lZ~Z~9;~:

in this manner is a preferred embodiment of the present invention. Thus, for the treat~ent of diabetic cataracts the compounds of this invention are administered to the eye of the subject in need of treatment in the form of an ophthalmic preparation prepared in accordance with conventional pharmaceutical practice, see for example "Remington's Pharmaceutical Sciences", 15th Edition, pages 1488 to 1501 (Mack~ Publishing Co., Easton, Pa.). The ophthalmic preparation will contain a compound of formula I, or a pharmaceutically acceptable salt thereof, in a concentration from about 0.01 to about 1% by weight, preferably from about 0.05 to about 0.5%, in a pharma-ceutically acceptable solution, suspension or ointment.
Some variation in concentration will necessarily occur, depending on the particular compound employed, the condition of the subject to be treated and the like, and the person responsible for treatment will determine the most suitable conc~ntration for the individual subject. The ophthalmic preparation will preferably be in the form of a sterile aqueous solution containing, if desired, additional ingredients, for example preservatives, buffers, tonicity agents, antioxidants and stabilizers, nonionic wetting or clarifying agents, viscosity-increasing agents and the like. Suitable preservatives include benzalkonium chloride, benz-ethonium chloride, chlorobutanol, thimerosal and the like. Suitable buffers include boric acid, sodium and potassium bicarbonate, sodium and potasssium borate, sodium and potassiu~ carbonate, sodium acetate, sodium biphosphate and the like, in amounts sufficient to maintain the pH at between about 6 and 8, preferably `2~3~3~

between about 7 and 7.5. Suitable tonicity agents are dextran 40, dextran 70, dextrose, glycerin, potassium chloride, propylene glycol, sodium chloride, and th`e like, such that the sodium chloride equivalent of the ophthalmic solution is in the range 0.9 plus or minus 0.2~. Suitable antioxidants and stabilizers include sodium bisulfite, sodium metabisulfite, sodium thiosulfite, thiourea and the like. Suitable wetting and clarifying agents include polysorbate 80, polysorbate 20, poloxamer 282 and tyloxapol.
Suitable viscosity-increasing agents include dextran 40, dextran 70, gelatin, glycerin, hydroxyethylcellulose, hydroxmethylpropylcellulose, lanolin, methylcellulose, petrolatum, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose and the like. The ophthalmic preparation will be administered topically to the eye of the subject in need of treat-ment by conventional methods, for example in the form of drops or by bathing the eye in the ophthalmic 5OlUtion.
The activity of the compounds of the present invention as agents for the control of chronic diabetic complications may be determined by a number of standard biological or pharmacological tests.
2~ Suitable tests include (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 and lens of acutely streptozotocinized, i.e.
diabetic, rats; (3~ measuring their ability to reverse already-elevated sorbitol levels in the sciatic nerve lZ9Z992 and lens of chronic streptozotocin-induced diabetic rats; (4) measuring the.r ability to prevent or inhibit galactitol formation in the lens of acutely galactosemic rats; (5) measuring their ability to delay cataract formation and reduce the severity of lens opacities in chronic galactosemic rats; (6) measuring their ability to prevent sorbitol accumulation and cataract formation in isolated rat lens incubated with glucose;
and (7) measuring their ability to reduce already elevated sorbitol levels in isolated rat lens incubated with glucose The present invention is illustrated by the following examples. It will be understood, however, that the invention is not limited to the specific details of these examples Proton nuclear magnetic resonance spectra (2;~MR) were measured at 250 MHz (unless otherwise indicated) for solutions in perdeuterodimethyl sulfoxide (Dt~SO-d6) and peak positions are expressed in E~arts per million (ppm) downfield from tetramethylsilane The peak shapes are denoted as follows: s, singlet; d, doublet; t, triplet;
q, quartet; m, multiplet; b, broad; very, v, rel 4,5'S 7'R Spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl To a solution of 13 3 g (0 138 mol) of ammonium car-bonate and 3 8 g (0 058 mol) of potassium cyanide in 53 ml of water was added a solution of 4 75 g (0 029 mol) of 7-methyl-7,8-dihydro-quinolin-5(6H)-one in 53 ml of ethanol The reaction was heated at 65C for 72 hours, The solution was cooled and filtered and the filtrate was brought to pH 6 5 at which point a gummy solid precipitated, The lZ9Z992 solid was filtered and washed well with water. Re-crystallization from ethanol gave 2.0 g of the title compound: mp. 252-254C as a mixture composed of 80% of the rel 7'R methyl diastereomer and 20~ of the rel 7'S methyl diastereomer. NMR (DMSO-d6): ~ 11.03 (vbs, lH); 8.76 (s, 0.8 x lH); 8.47 (m, lH); 8.36 (s, 0.2 x lH); 7.68 (m, 0.2 x lH); 7.46 (m, 0.8 xlH); 7.27 (m, lH); 2.85-3.0 (m, lH); 2.35-2.6 (m, lH); 2.0-2.2 (m, lH); 1.75-2.0 (m, 0.8xlH); 1.64 (t, 0.2xlH); 1.09 (d, 0.8x3H); and 1.05 (d, 0.2x3H) ppm.

rel 4,5'S 7'S Spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl Concentration of the ethanol mother liquors from preparation of material enriched in the rel 4,5'S 7'R
diastereomer of Example 1 and recrystallization from ethyl acetate gave 1.45 g of material which was re-crystallized from water to give 860 mg of rel 4,5'S
7'S spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl: mp 145-152C as a mixture of 90~ rel 7'S methyl diastereomer and 10% rel 7'R methyl diastereomer. NMR (DMSO-d6): ~ 10.88 (vb s, 1, ~IH);
8.76 (s, O~lxl, NH); 8.5 (m,lH); 8.36 (s, O.9xl,NH);
7.68 (m, O.9xlH); 7.46 (m, O.lxlH); 7.27 (m, lH);
2.9-3.05 (m,lH); 2.5-2.75 (m, lH); 2~35-2.5 (m,lH);
2.05-2.15 (bd, lH); 1.75-1.95 (m, 0.1 xlH); 1~64 (t, O.9xlH), 1.09 (d, O.lx3H); and 1.05 (d, O.9x3H) ppm.

rel 4,5'S 7'R Spirolimidazolidine-4,5'(6'H)-quinoline]-2~5-dione-7~8'-dihydro-7'-methY~ -oxide 1.0 g (4.32 mmol) of a 65:35 diastereomer mixture of rel 4,5'S 7'R and 4,5'S 7'S spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl was dissolved in a solution of 0.72 ml (7.0 mmol) of 30 percent 1292~92 hydrogen peroxide in 3.0 ml glacial acetic acid and was heated at 85C for 15 hours. A test for peroxide with potassium iodide-starch test paper showed no peroxide present The reaction mixture was concentrated in vacuo to an orange foam which was triturated with an ethyl acetate, diethyl ether, methanol mixture to afford a tan colored solid amounting to 650 mg: mp 185-195C
of a 75:25 mixture of the 4,5'S 7'R to 4,5'S 7'S
diastereomers NMR (DMSO-d6): ~ 8.8 (b s, lH); 8.32 (m, lH); 7.35 (m, lH); 7.1 (m, lH); 3.05-3.35 (m,_H);
1.8-2.6 (m,_H); 1.1~ (d, 0.75x3H); and 1.10 (d, 0 25 x 3H) ppm.

rel 4,5'S 7'S Spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl-1'-oxide Concentration of mother liquors from precipitation of the rel 4,5'S 7'P. diastereomer of Example 3 and trituration with one-to-one diethyl ether-hexane gave 60 mg of a 70:30 mixture of the 4,5'S 7'S to 4,5'S 7'R
diastereomers: mp 261-264C NMR (DMSO-d6): ~ 8.82 (s, 0.3xlH); 8.46 (s, 0.7xlH); 8.3 (t, lH); 7.35 (d, 0.7xlH);
7.1 (d, 0.3xlH); 3.05-3.35 (m,2H); 1.5-2.3 (m, 3H):
1.15 (d, 0.3x3H); and 1.0 (d, 0.7x3H) ppm.
EXAMP~E 5 rel 4,5'S 7'S, 8'R Spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-8'-hydroxy-7'-methyl 2.7 g (11.68 mmol) of a 65:35 diastereomer mixture of rel 4,5'S 7'R and 4,5'S 7'S spiro~imidazolidine-4,5' (6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl was dissolved in a solution of 2.11 ml (20.5 mmol) of 30 percent hydrogen peroxide in 8.1 ml of glacial acetic acid and was heated at 90C for 17 hours. A test for peroxide with potassium iodide-starch paper showed no peroxide present.
The reaction was concentrated in vacuo to a yellow oil.
Trituration with ethanol gave 3.35 g of a yellow foam after the solvent was removed in vacuo. To the foam (3.33 g) lZ9299~

was added 14 ml of acetic anhydride plus 2 drops of water and the reaction was stirred at 95C for 20 min to give a c:lear yellow solution. The reaction was concentrated ln vacuo, ethanol was added and was reconcentrated in vacuo.
Repetition of this procedure gave 3.8 g of a tan foam, which was slurried in 100 ml water and a 5 percent aqueous sodium hydroxide solution was added. The reaction mixture was stirred until a clear solution resulted. Thin layer chromatographic analysis (20% methanol, 80% chloroform eluent) on silica gel plates showed the appearance of four new more polar spots visible using 254 nanometer ultraviolet light. ~he solution was neutralized with concentrated hydrochloric acid to pH 7, and was extracted with five-100 ml portions of ethyl acetate.
After drying over anhydrous sodium sulfate, concentra-tion ln vacuo gave 1.84 g of a tan foam.

r ~ Diastereomer Separation Products were separated by ' high pressure liquid chromatography using a Dupont 880 HPLC, Zorbax preparative silica gel column, linear gradient starting from 95:5 methylene chloride-methanol to 85:15 methylene chloride-methanol over 20 min., 20 ml/min flow rate with ultraviolet detection at 254 nanometers. A portion of the crude product (1.33 g.) was dissolved in 7 ml of 95:5 methylene chloride-methanol.
Injections of 0.5 to 1.0 ml were made. Peaks corre-sponding to 5 components were isolated which did not correspond to the elution order observed by thin layer chromatographic analysis.
Peak 1 by high pressure liquid chromatography (HP~C) corresponded to the 2nd least polar spot by thin layer chromatography (TI.C). Peak 2 by HPLC corresponded to the 3rd least polar spot by TLC, Peak 3 by HPLC corresponded ~f ~Cle ~ k ~29Z~392 to the least polar spot by ~LC. Peak 4 by HPLC
exhibited retention time identical with the 3rd Least polar spot by ~LC. Peak 5 by HPLC corresponded to the most polar spot by TLC.
Material corresponding to HPLC peak 1 was re-crystallized from methanol to give material with mp 239-242C. Based on the following nuclear magnetic resonance spectral properties it was identified as rel 4,5'S 7'S, 8'R spirolimidazolidine-4,5'(6'H)-quinoline]-2,5-dione- 7',8'-dihydro-8'-hydroxy-7'-methyl. NMR (DMSO-d6): ~ 11.1 (bs, 1, NH); 8.86 (s, 1, NH) 8.61 (m, lH): 7.50 (m, lH) 7.38 (m,lH) 5.35 (bs, 1, OH); 4.13 (d, lH, 8'-H, D2O addition J = 7.5Hz); 1.8-2.15 (m, 3H); and 1.15 (d, 3H)ppm~

rel 4,5'S 7'R, 8'S spiro[imidazolidine-4,5'(6'H)-quinoline~-2,5-dione-7',8'-dihydro-8'-hydroxy-7'-methyl Material corresponding to HPLC peak 2 was re-crystallize~ from diethyl ether-methanol-ethanol mixture to give material with mp 236-239C. Based on the following nuclear magnetic resonance spectral properties it was identified as the title compound. NMR (DMSO-d6):
10 9 (vbs, 1, NH); 8 60 (m, lH); 8 36 (s, 1, NH);
7 61 (m, lH); 7.36 (m, lH); 5.28 (bs, 1, OH); 4.08 (d, lH, J = 10Hz); 2.5 (m, lH); 2.1 (d, lH); 1.87 (t, lH); and 1.12 (d,3H) ppm.

rel 4,5'S spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7'-methyl Material corresponding to HP~C peak 3 was recrys-tallized from a diethyl ether-methanol-ethanol mixture to give material with mp 228-231C. Based on the iZ~2~392 ~ollowing nuclear magnetic resonance s~ectral properties it was identified as the title compound. NMR (DMSO-d6):
10.97 (vbs, 1. NH); 8.64 (s, 1, NH); 8.43 (m, lH);
7.46 (m, lH); 7.20 (m, lH); 6.39 (s, 1, CH=C); 2.67 (q, 2H); and 1.94 (s, 3H) ppm.

rel 4,5'S 7'R, 8'R spirolimidazolidine-4,5'(6'H)-quinoline]
2,5-dione-7',8'-dihydro-8'-hydroxy-7'-methyl Material corresponding to HPLC peak 4 was recrys-tallized from a diethyl ether-methanol mixture to give material with mp 252-256C. sased on the following nuclear magnetic resonance spectral properties it was identified as the title compound. NMR (DMSO-d6): ~ 10.85 (vbs, 1, NHl; 8.55 (m, lH); 8.47 (s, 1, NH); 7.37 (s, lH); 5.42 (m, 1, OH); 4.44 (bd, lH, J = 2.5Hz); 2.5 (m, lH); 2,17 (m, lH); 1,77 (m, lH); and 0.96 (d, 3H) ppm.

rel 4,5'S 7'S, 8'S spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-8'-hydroxy Material corresponding to HPLC peak 5 was recrys-tallized from diethyl ether to give material with mp 238-241C. Based on the following nuclear magnetic resonance spectral properites it was identified as the title compound. MMR (DMSO-d6): ~ 11.06 (vbs, 1, NH);
8.71 (s, 1, NH); 8.56 (m, lH); 7O5 (m, lH); 7.37 (m, lH); 5.40 (d, 1, OH); 4.37 (bs, lH, 8'-H, D2O
addition, J = 2.5Hz); 2.32 (t, lH); 2.14 (m, lH);
1.59 (d, lH); and 1.06 (d, 3H) pp~.
EX~MP~E 6 Spiro~imidazoline-4,5'(6'H)-quinoline~-2,5-dione 3'-chloro-7',8'-dihydro-7'-methyl LO a solution of 28.8 mg (0 44 mmol) of potassium cyanide and 100 mg (1.04 mmol) of ammonium carbonate in 4 ml of ethanol and 4 ml of water was added 40 mg (0.204 mmol) 12~Z~392 of 3-chloro-7-methyl-7,8-dihydroquinolin-5(6H)-one and the reaction was stirred at 65C for 24 hours. An addi-tional 101 mg of ammonium carbonate was added and heating was continued for 72 hours. An additional 101 mq of ammonium carbonate and 3 ml ethanol and 2 ml water, was added and heating was continued at 65C for 24 hours.
An additional 101 mg of ammonium carbonate was added and heating was continued for 6 days. The ethanol was removed from the dark~reaction solution by concentration in vacuo. The residue was diluted with water and the pH was brought to 7 with aqueous hydrochloric acid and the reaction was extracted with two 50 ml portions ethyl acetate. After drying over anhydrous sodium sulfate, the solution was concentrated ln vacuo to 30 mg of a dark~green solid. High resolution mass spectroscopic analysis confirmed the presence of the title compound.
Calculated for C12H12M3O2Cl exact mags~m/e 265-0619-Found: 265.0624.
PREPARATION
3-Chloro-7-methyl-7,8-dihydroquinolin-5(6H)-one To 2.14 g (0.018 mol) of 2-chloro-3-dimethylamino-acrolein in 20 ml dimethylformamide was added 2.25 g (0.018 mol) of 3-amino-S-methyl-cyclohex-2-enone. The reaction was heated at reflux for 40 hours. Most of the solvent was removed in vacuo and the residue was triturated with petroleum ether and concentrated in vacuo. This procedure was repeated three times. The resultant amber oil was triturated with 50 ml of ethyl acetate and filtered to remove an insoluble black~powder. The ethyl acetate mother liquors were concentrated in vacuo to give 1.54 g of a dark~brown oil. This material (0.93 g) was subjected to column chromatography on silica gel using ethyl acetate lZ9Z~9Z

as eluent. Material with Rf of 0.45 was isolated as a brown oil. ~he material was identified as largely con-t:aining the title compound based on the following spectral data. Mass spectrum base peak, m/e 195, with ratio 195:197 of 3:1 corresponding to chlorine isotopes.
NMR (DMSO-d6): ~ 8.78 (d, lH, J = 2.5Hz); 8.15 (d, lH, J = 2.5Hz); 2.2-3.2 (m, 5H); and 1.14 (d, 5H) ppm.

Claims (40)

1. A process for preparing a spiro-heteroazolone compound of the for-mula I

or a pharmaceutically acceptable salt thereof, wherein A is methylene, hydroxy-methylene, or methine; Y is methylene, alkylmethylene, methine or alkyl-methine, wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when A is methine, Y is methine or alkylmethine; Z is oxygen, sulfur, or nitrogen substituted by hydrogen; Q is nitrogen or nitrogen-N-oxide; and X is in the 3'-position and is hydrogen, halo, alkyl, alkoxy having 1-4 carbon atoms, alkylthio, alkylsulflnyl, alkylsulfonyl, phenoxy, phenylthio, or nitro;
or X is in the 2'-position and is hydrogen, alkyl, or alkoxy having 1-4 carbon atoms; wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when Q is nitrogen-N-oxide, X is not alkylthio, alkylsulfinyl or phenylthio; and with the further proviso that when Q is nitrogen and X is hydrogen and Z is nitrogen substituted by hydrogen, at least one of A and Y is always other than methylene, which process comprises:
(a) condensing an appropriately substituted carbonyl ring compound of the formula:

IV

P.C. 6849 CA 28 wherein X is a previously defined and R is hydrogen or alkyl having 1-4 carbon atoms, with an alkali metal cyanide and ammonium carbonate to form the corresponding spiro-hydantoin final product of the formulas IA

wherein Z is nitrogen substituted by hydrogen and X and R are each as previously defined; or (b) reacting a compound of formula IV as defined above with a trialkylsilyl cyanide (wherein each alkyl has 1-4 carbon atoms) in the present of a Lewis acid to produce a corresponding cyano trialkylsilyloxy derivative, then reacting the cyano trialkylsilyloxy derivative with an acid in an alcohol solvent to convert it into an alkyl-hydroxycarboximidate derivative, and finally treating the alkyl-hydroxycarboximidate with (i) phosgene in the presence of a base in an inert organic solvent, (ii) a C1-C4 alkyl haloformate in an inert solvent followed by heating, or (iii) 1,1'-carbonyl-diimidazole neat or in an inert solvent, to convert into a spiro-oxazolidin-2,5-dione of formula IA as defined above (wherein Z is oxygen, or sulfur); and - 29a - 64680-338 (c) when required, oxidizing a compound of the formula IA wherein Z is as originally defined and X is not alkylthio, alkylsulfinyl or phenylthio to a corresponding compound of the formula:

IB
wherein X, Z and R are each as previously defined except that X is not alkylthio, alkylsulfinyl or phenylthio; and (d) when required, transforming a compound of the formula IB into a compound of the formulae:

or IC ID

wherein X, Z and R are each as previously defined, except that X is not alkyl-thio, alkylsulfinyl or phenylthio, by reacting the formula IB compound with acetic anhydride in an acidic medium, followed by hydrolysis of the resulting acetate salt in an aqueous solvent at a pH of at least about pH 10;
and thereafter, if desired, converting a compound of formula IA, IB, IC or ID to a pharmaceutically acceptable salt thereof, whereby a spiro-heteroazolone compound of formula I or a pharmaceutically salt thereof is ob-tained.

2. A process as claimed in claim 1, wherein the condensation reaction part (a) is carried out and a compound of formula IA (wherein Z is nitrogen substituted by hydrogen, X and R are as defined in claim 1) is produced.

3. A process as claimed in claim 2, wherein the condensation reaction is carried out by employing a slight molar excess of the alkali metal cyanide reagent with respect to the carbonyl ring compound starting material.

4. A process as claimed in claim 2, wherein the condensation reaction is carried out in an aqueous reaction-inert polar organic solvent medium at a temperature that is in the range of from about 20°C. to about 120 C.

5. A process as claimed in claim 4, wherein the organic solvent is a water-miscible lower alkanol.

6. A process as claimed in claim 1, wherein the third step of part (b) comprises reacting the hydroxycarboximidate derivative [i] with phosgene in the presence of a base; or [ii] with an alkyl haloformate in which the alkyl group is of 1 to 4 carbon atoms, followed by heating; or [iii] with 1,1'-carbonyldiimidazole, whereby a compound of formula IA (wherein Z is oxygen) is produced.

7. A process as claimed in claim 1, wherein the third step of part (b) comprises heating the hydroxycarboximidate derivative with thionyl chloride to convert to a chlorocarboximidate derivative; reacting the chlorocarbox-imidate derivative with thiourea; followed by hydrolysis.

8. A process as claimed in claim 1, wherein said oxidation reaction of part (c) is carried out with 30% aqueous hydrogen peroxide in an acidic solvent at a temperature in the range of from about 0 C. to about 100 C.

9. A process as claimed in claim 1, wherein said transformation reaction of part (d) is carried out with acetic anhydride in acetic acid or neat con-taining a trace of water at a temperature in the range of from about 60°C. to about 95°C., followed by hydrolysis of the resulting acetate salt in water at a pH in the range of about pH 10 to about pH 14.

10. A process as claimed in claim 1, wherein the condensation reaction of part (a) followed by the oxidation of part (c) is carried out, whereby a compound of formula IB (wherein Z is nitrogen substituted by hydrogen and X
and R are as defined in claim 1 provided that X is not alkylthio, alkylsulfinyl or phenylthio) is produced.

11. A process as claimed in claim 1, wherein the condensation reaction of part (a), the oxidation of part (c) and the transformation of part (d) are carried out; and a compound of formula IC (wherein Z is nitrogen substituted by hydrogen and X and R are as defined in claim 1 provided that 2 is not alkylthio, alkylsulfinyl or phenylthio) is isolated.

12. A process as claimed in claim 1, wherein the condensation reaction of part (a), the oxidation of part (c) and the transformation of part (d) are carried out; and a compound of formula ID (wherein Z is nitrogen substituted by hydrogen and X and R are as defined in claim 1 provided that R is not alkylthio, alkylsulfinyl or phenylthio) is isolated.

13. A process as claimed in claim 1 or 2, wherein in the formulae X is hydrogen or is in the 3'-position and is chloro.

14. A process as claimed in claim 6, 7 or 10, wherein in the formulae X is hydrogen or is in the 3'-position and is chloro.

15. A process, as claimed in claim 11 or 12, wherein in the formulae X
is hydrogen or is in the 3'-position and is chloro.

16. A process as claimed in claim 1 or 2, wherein in the formulae R is methyl.

17. A process as claimed in claim 6, 7 or 10, wherein in the formulae R is methyl.

18. A process as claimed in claim 11 or 12, wherein in the formulae R is methyl.

19. A spiro-heteroazolone compound of the formula I as defined in claim 1 or a pharmaceutically acceptable salt thereof, when produced by the process of claim 1 or by an obvious chemical equivalent thereof.

20. A process for producing rel 4,5'S 7'S or R spiro-[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl or a mixture thereof, which process comprises:
condensing 7-methyl-7,8-dihydro-quinolin-5(6H)-one with potassium cyanide and ammonium carbonate to form a condensation reaction mixture contain-ing both the rel 7'R methyl diastereomer and the rel 7'S methyl diastereomer, and if desired, separating the rel 7'S methyl diastereomer or the rel 7'R
methyl diastereomer from each other.

21. A process as claimed in claim 20, wherein the rel 7'R methyl diastereomer is separated from the condensation reaction mixture.

22. A process as claimed in claim 21, wherein the condensation reaction is carried out by employing about two moles of potassium cyanide per mole of the ketone compound.

23. rel 4,5'S 7'R Spiro[imidazolidine-4,5'(6'H)-quinoline7-2,5-dione-7', 8'-dihydro-7'-methyl, whenever produced by the process of claim 21 or 22 or or by an obvious chemical equivalent thereof.

24. A process for producing rel 4,5'S 7'S or R spiro[imidazolidine-4,5'(6lH)-quinolin]7-2,5-dione-7',8'-dihydro-7'-methyl-1'-oxide or a mixture thereof, which process comprises oxidizing rel 4,5'S 7'S or R spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl or a mixture thereof, produced by the process of claim 20, and if desired, separating the rel 7'S methyl diastereomer or the rel 7'R methyl diastereomer from each other when a mixture of the diastereomers is employed as the starting material.

25. A process as claimed in claim 24, wherein a mixture of the di-astereomers is used as the starting material and the rel 7'R methyl diastereomer is separated after the oxidation.

26. A process as claimed in claim 24, wherein the oxidation is carried out using hydrogen peroxide.

27. rel 4,5'S 7'R Spiro[midazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl-1'-oxide, whenever produced by the process of claim 25 or 26 or by an obvious chemical equivalent thereof.

28. A process for producing rel 4,5'S 7'S or R, 8'R or S spiro[imidazo-line-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-8'-hydroxy-7'-methyl, which process comprises:
reacting rel 4,5'S 7'S or R spiro[imidazolidine-4,5'(6'H)-quinolin]-2,5-dione-7',8'-dihydro-7'-methyl-1'-oxide or a mixture thereof, produced by the process of claim 24, with acetic anhydride in an acidic medium, followed by hydrolysis of the resulting acetate salt in an aqueous solvent at a pH of 10 to 14, and separating the desired compound from the reaction mixture.

29. A process as claimed in claim 28, wherein rel 4,5'S 7'R, S'S spiro [imidazolidine-4,5'(6'H)-quinolin]7-2,5-dione-7'8'-dihydro-8'-hydroxy-7'-methyl is separated from the other diastereomers.

30. A process as claimed in claim 28, wherein a mixture of the diastereo-mers is used as the starting material.

31. rel 4,5'S 7'R, S'S Spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-8'-hydroxy-7'-methyl, whenever produced by the process of claim 29 or by an obvious chemical equivalent thereof.

32. A process for producing rel 4,5'S spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7'-methyl, which process comprises:
reacting rel 4,5'S 7'S or R spiro[imidazolidine-4,5'(6'H)-quinoline]-2,5-dione-7',8'-dihydro-7'-methyl-1'-oxide or a mixture thereof, produced by the process of claim 24, with acetic anhydride in an acidic medium, followed by hydrolysis of the resulting acetate salt in an aqueous solvent at a pH of 10 to 14, and separating the desired compound from the reaction mixture.

33. rel 4,5'S Spiro[imidazolidine-4,5'(6'H)-quinolin]7-2,5-dione-7'-methyl, whenever produced by the process of claim 32 or by an obvious chemical equivalent thereof.

34. A spiro-heteroazolone compound of the formula (I) or a pharmaceutically acceptable salt thereof, wherein A is methylene, hydroxymethylene, or methine; Y is methylene, alkylmethylene, methine or alkylmethine, wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when A is methine, Y is methine or alkylmethine; Z is oxygen, sulfur, or nitrogen substituted by hydrogen; Q is nitrogen or nitrogen-N-oxide; and X is in the 3'-position and is hydrogen, halo, alkyl, alkoxy having 1-4 carbon atoms, alkylthio, alkylsulfinyl, alkylsulfonyl, phenoxy, phenylthio or nitro; or X is in the 2'-position and is hydrogen, alkyl or alkoxy having 1-4 carbon atoms; wherein alkyl in each instance has 1-4 carbon atoms; with the proviso that when Q is nitrogen-N-oxide, X is not alkylthio, alkylsulfinyl or phenylthio; and with the further proviso that when Q is nitrogen and X is hydrogen and Z is nitrogen substituted by hydrogen, at least one of A and Y is always other than methylene.

35. The compound or salt according to claim 34, wherein X is hydrogen or is in the 3'-position and is chloro.

36 36. The compound or salt according to claim 34, wherein Z
is nitrogen substituted by hydrogen and Q is nitrogen or nitrogen N-oxide.

37. The compound or salt according to claim 34, wherein Y is methylmethylene, A is methylene or hydroxymethylene and X is hydrogen or chloro.

38. The compound or salt according to claim 34, wherein A is methine, Y is methylmethine and X is hydrogen.

39. The compound or salt according to claim 34, wherein the compound has the formula (wherein Q, Z and X are as defined in claim 34, with the proviso that Z is not nitrogen substituted with hydrogen, when Q
is nitrogen and X is hydrogen).

40. A pharmaceutical composition for preventing or treating diabetes, which comprises an aldose reductase inhibition effective amount, of the compound or salt as defined in any one of claims 36 to 39 in admixture with a pharmaceutically acceptable carrier.