PROCESS FOR THE PREPARATION OF 2-CHLOROSULFONYL-4-(N-SUBSTITUTED SULFAMYL)-CHLOROBENZENE COMPOUNDS

Abstract: A process for the preparation of 2-chlorosulfonyl-t-(N-­ substituted sulfamyl)-chlorobenzene compounds of the gen­ eral formula: wherein R is a hydrogen atom or a lower alkyl group, X is a 5- or 6-membered carbocyclic group which may contain an oxygen atom or atoms as ring-constituting members and may be substituted on the ring by one or more lower alkyl groups, and n is 0 or 1, which process comprises reacting a 2,4-dichloro­ sulfonylchlorobenzene of the formula: with an amine of the general formula: R - NH - (CH₂) n - X (III) wherein R, X and n are as defined above, in the presence of an acid-binding agent at a temperature of below 10°C.

Description: PROCESS FOR THE PREPARATION OF 2-CHLOROSULFONyL-4- (N-SUBSTITUTED SULFAMYL)-CHLOROBENZENE COMPOUNDS The present invention relates to a new process for the preparation of 2-chlorosulfonyl-4-(N-substituted sulfamyl)-chlorobenzene compounds. More particularly, the present invention relates to a new industrially valuable process for the preparation of 2-chlorosulfonyl-4- (N-substituted sulfamyl)-chlorobenzene compounds in one stage fram 2,4-dichlorosulfonyl-chlorobenzene. 2-Chlorosulfonyl-4-(N-substituted sulfamyl) chlorobenzene compounds are known to be important as intermediates in the preparation of certain compounds having pharmacological activity. For example, -2 chlorosulfonyl-4- fN-methyl-N- (a-methyltetrahydrofur- furyl)-sulfamyl)-chlorobenzene of the formula: EMI1.1 is useful as an intermediate in the preparation of a substance exhibiting excellent diuretic activity, i.e. this compound is extremely valuable as a precursor for 2-sulfamyl-4-IN-methyl-M-(a-methyl tetrahydrofurfuryl)- sulfamyl]-chlorobenzene of the formula: EMI2.1 However, these 2-chlorosulfonyl-4-(N-substituted sulfamyl)-chlorobenzene compounds, the end products of the present invention, have heretofore been prepared by an industrially very disadvantageous method. Previously, it was practically impossible to effect amidation at the 4-position alone of 2,4-dichloro-sulfanyl-chloro buwsne. In the prior art methods, therefore 2-dichlorosulfan-4- sulfamyl)-chlorobenzenecompounds were prepared by incorporating at the 2-position of 4-chlorosulfonyl-chlorobenzene, a functional group which is not sensitive to amidation Of the chlorosulfonyl group in the 4-position (i.e. sulfamylation), and then converting the functional group in the 2-position, after the amidation in the 4-position with an amine, to a chlorosulfonyl group by a multistage reaction including the Meerwein reaction. These methods require several reaction vessels and are complicated and troublesome operations which are quite disadvantageous, particularly in that the overall yield of the end product does not reach a satisfactory level and the methods per se are not commercially attractive. There is thus a great demand in this art for developing a new advantageous method for preparing 2-chlorosulfonyl-4-(N-substituted sulfamyl)-chlorobenzene compounds in a high yield without the above-mentioned drawbacks. We have now surprisingly found that 2-chlorosulfonyl-4-(N-substituted sulfamyl)-chlorobenzene can be successfully be prepared in a high yield in one step from 2,4-dichlorosulfonyl-chlorobenzene by selectively effecting amidation of the chlorosulfonyl group in the 4-position only. In accordance with the present invention, there is provided a process for the preparation of 2-chloro sulfonyl-4- (N-substituted sulfamyl)-chlorobenzene compounds of the general formula: EMI3.1 wherein R is a hydrogen atom or a lower alkyl group, X is a 5- or 6-membered carbocyclic group which may contain an oxygen atom or atoms as ring-constituting members and may be substituted on the ring by one or more lower alkyl groups and n is 0 or 1, which process comprises reacting a 2,4-dichlorosulfonyl-chlorobenzene of the formula: EMI4.1 with an amine of the general formula: : R - NH - (CH2)n - X (III) wherein R, X and n are as defined above in the presence of an acid-binding agent at a temperature of below 100 C, preferably below OOC and more preferably below -400C. Of the reactants used in the process of this invention, 2, 4-dichlorosulfonyl-chlorobenzene of the formula (II) is commercially available and can easily be prepared by the chlorosulfonation of chlorobenzene using a conventional procedure. Primary or secondary amines of the general formula (III) are known and also commercially available. These amines can of course be prepared as required by methods known per se. The group R is a hydrogen atom or a lower alkyl group which may be straightor branched chain and contains 1 to 6 carbon atoms. Examples of R as an alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl and 2-ethylbutyl. The group X in principle contains no unsaturated double bond and is generally a Cos¯6 alicyclic group which contains one or two oxygen atoms as ring-constituting members in place of one or two ring carbon atoms and may be substituted by one or two lower alkyl groups on the ring carbon atoms. This lower alkyl group as a ring substituent is of the same type as referred to above with respect to the group R. Examples of the group X thus include cyclopentyl, cyclohexyl, tetrahydrofurfuryl, tetrahydropyranyl and 1,4-dioxan-2-yl, as well as their ringsubstituted lower: alkyl homologs. Any base usually employed for condensation reactions accompanied by the liberation of an acid can be used as the acid-binding agent in the process of this invention. Examples of suitable acid-binding agents arse inorganic bases such as alkali metal hydroxides, for example, sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides, for example, calcium hydroxide and barium hydroxide, and alkali metal carbonates and bicarbonates, for example, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate; and organic bases such as tertiary amines, for example, triethylamine, tri-npropylamine, tri-n-butylamine, pyridine, picolines, lutidines and collidines, and quaternary ammonium hydroxides, for example, tetramethylammonium hydroxide. The use of a tertiary amine, especially triethylamine, is preferred because it forms a homogeneous system with the solvent used and the amine of the general formula III. Any organic solvents which is inert to the reaction can be used in the process of this invention. Illustrative of utilizable organic solvents are, for example, ethers such as diethyl ether, tetrahydrofuran and dioxane; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate and ethyl propionate; and organic tertiary bases such as pyridine, triethylamine and trin-propylamine. In general, polar solvents as exemplified above are preferred to non-polar solvents such as aromatic hydrocarbons, because the latter tend to involve disadvantages in after treatments. As organic tertiary bases such as pyridine or triethylamine function both as the acid-binding agent and solvent, a large excess amount of the organic tertiary base can be used for such dual purpose. The reactants in the process of this invention, i.e., 2,4-dichlorosulfonyl-chlorobenzene and an amine of the general formula (III) are generally used in a stoichiometric amount. However, either of the reactants may be used in a slight excess amount. The acid-binding agent is generally used in a stoichi- metric amount necessary to combine with the acid liberated during the condensation reaction of the reactants. When an organic tertiary base is used it may be used in a large excess amount so that it is also effective as the organic solvent. The process of the present invention is generally carriedout.ky adding a solution. of an amine of the general formula (III) and the acid-binding agent in an organic solvent to a solution of 2,4-dichlorosulfonyl-chlorobenzene in the organic solvent and the mixture is then stirred until the condensation reaction is completed. The use of the same organic solvent to dissolve the reactants is convenient to simplify the after-treatment. The above condensation reaction should be carried out at a temperature below 10 C, preferably 0 C and more preferably -400C. The establishment of this low reaction temperature is the most important feature of the present invention. Under these low temperature conditions, the 4-chlorosulfonyl group alone of the starting 2, 4-dichlorosulfonyl-chlorobenzene is selectively amidated but the 2-chlorosulfonyl group is not attacked, or even if it is attacked, the resultant 2-amidated andi or 2,4-diamidated product is present in an extremely small amount and can easily be separated and eliminated from the desired product after the reaction. The formation of such by-products becomes negligible as the reaction temperature adopted is lowered. Accordingly, the reaction can advantageously be conducted at a temperature below 00C,.preferably -400C. As the amidation.takes place selectively in the 4-position of the starting 2,4-dichlorosulfonyl-chlorobenzene, the end product is obtained not only in a very high yield but also very pure. After completion of the reaction, the reaction mixture is treated in a conventional manner to isolate the end product in a pure state. For example, the reaction mixture may be concentrated to dryness under reduced pressure whereby the solvent used is recovered. The residue is then purified by column chromatography or preparative thin layer chromatography using, for example, silica gel as sorption agent followed by recrystallization from benzene-n-hexane. If necessary, the residue may be subjected to a preliminary purifying treatment prior to the chromatographic purification, which comprises taking up the residue in a waterimmiscible organic solvent, washing the solution with water several times and then removing the solvent under reduced pressure. Such a preliminary purifying treatment is sometimes necessary when an inorganic acid-binding agent is used in the main reaction step. The thus purified end product is usually in the form of a white crystalline powder. It is indeed a most important advantage of the presentinvention that the amidation reaction takes place selectively in the 4-position only of the starting 2,4-dichlorosulfonyl-chlorobenzene so that, the end product can be obtained in a high yield and with good purity. Furthermore, some additional advantages can also be achieved by the present invention. First, the product produced by the present: invention represented by the general formula (I) can be further reacted, without the necessity of isolation from the reaction liquid, directly with ammonia or a substance capable of producing ammonia, such as ammonium hydroxide or ammonium carbonate, whereby the 2-chlorosulfonyl group in the compound of the general formula (I) can readily be converted into a 2-sulfamyl group to produce a compound of the general formula EMI10.1 wherein R, X and n are as defined above, which is useful as a diuretic. Thus, the process of this invention is of important utility from an industrial point of view. Secondly, the process of this invention is advantageous in that a pharmacologically useful sulfamyl compound of the general formula (V), for example, 2-sulfamyl-4-±N-methyl-M- (a-methyltetra- hydrofurfuryl)-sulfamyll-chlorobenzene can be prepared economically in.3 steps starting from chlorobenzene and in only 2 steps starting from 2,4-dichlorosulfonylchlorobenzene. In addition, a pharmacologically valuable compound of the general formula (V) can be obtained, as described above, from the end product of the present invention, i.e. 2-chlorosulfonyl-4-lN-substituted sulfamyl) chlorobenzene of the general formula (I) by the treatment described above. A great economic advantage can thus be achieved by the process of the present invention. The present invention will now be:illustrated in more detail by way of examples and reference examples. In the reference examples, a series of reactions starting from 2, 4-dichlorosulfonyl-chlorobenzene for preparing pharmacologically valyable compounds are illustrated wherein the process of the present invention is included as the former half of the reaction. In laboratory scale reactions illustrated in these examples and reference examples, a temperature as low as-690C of the solution was made by external cooling of the reaction vessels containing the solution with a mixture of trichlorothylene and dry ice as the coolant. A mixture of dry ice and ethanol may also be used as the coolant. Example 1 Preparation of 2-chlorosulfonyl-4-tN-methyl- N- (a-methyltetrahydrofurfuryl) -sulfamyl] - chlorobenz ene 2-Methyltetrahydrofurfuryl-niethylamine (1.3 g) and triethylamine (1.2 g) were dissolved in ethyl acetate (5 ml). This solution was added to a solution which had been prepared by dissolving 2,4-dichlorosulfonyl-chlorobenzene (4.4g) in ethyl acetate (25 ml) and cooled at -680C. After completion of the reaction, the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography for purification and then recrystallized from benzene-n-hexane whereby the title compound was obtained as a white crystalline powder in a yield of 3.9 g (97* of the theoretical amount). M.P. 75.80C Elementary analysis as C,3H,7Cl2NO5S2 OM.W. 402.31) Calc: S, 15.94% ; Found: S, 15.928 Example 2 Preparation of 2-chlorosulfonyl-4-lN-(a- methyl-tetrahydrofurfuryl) - sulfamyl 1 -chlor benzene N-Methyltetrahydrofurfurylamine (1.2 g) and triethylamine (1.2 g) were dissolved in ethyl acetate (5 ml). This solution was added to a solution which had been prepared by dissolving 2, 4-dichlorosulfonyl-chlorobenzene (4.4 g) in ethyl acetate (25 ml) and cooled at -690C. After completion of the reaction, the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography for purification and then recrystallized from benzene-n-hexane whereby 2chlorosulfonyl-4-[N-(a-methyltetrahydrofurfuryl)-sulfamyl]chlorobenzene was obtained as a white crystalline powder in a yield of 3.3 g (85%). Example 3 Preparation of 2-chlorosulfonyl-4-(Nemethyl- N-cyclohexyl)-sulfamyl-chlorobenzene N-Methylcyclohexylamine (3.4 g) and triethylamine (3.4 g) were dissolved in ethyl acetate (12 ml). This solution was added to a solution which had been prepared by dissolving 2,4-dichlorosulfonyl-chlorobenzene (14.0 g) in ethyl acetate (93 ml) and then cooled at -69 C. After completion of the reaction, the solvent was distilled off under reduced pressure and the residue was subjected to column chromatography for purification and then recrystallized from benzene-n-hexane whereby 2-chlorosulfonyl-4 (N-methyl-N-cyclohexyl) -sulfamyl-chlorobenzene was obtained as a white crystalline powder in a yield of 11.0 g (95%). Reference Example 1 Preparation of 2-sulfamyl-4-tN-methyl- N- (a-methyltetrahydrofurfuryl) - sulfamyl] - chlorobenzene 2-Methyltetrahydrofurfuryl-methyalmine (3.9 g) and triethylamine (3.4 g) were dissolved in ethyl acetate (18 ml). This solution was added to a solution which had been prepared by dissolving 2,4-dichlorosulfonylchlorobenzene (14.0 g) in ethyl acetate (70 ml) and then cooled at -400C to effect reaction. After completion of the reaction, 28% ammonia water (28.0 ml) was added at -400C to the reaction mixture and then the temperature of the mixture was elevated up to -5 C. The reaction mixture was then allowed to stand for phase separation and the aqueous layer was discarded. The organic layer was concentrated under reduced pressure to distill off the solvent and the residue was crystallized from methanol whereby the title compound was obtained as a white crystalline powder in a yield of 9.3 g (80%). M.P. 1490C Reference Example 2 Preparation of 2-sulfamyl-4-TN-methyl- N-( -methyltetrahydrofurfuryl)-- sulfamyll-chlorobenzene 2-Methyltetrahydrofurfuryl-methylamine (3.9 g) and triethylamine (3.4 g) were dissolved in acetone (15 ml). This solution was added to a solution which had been prepared by dissolving 2, 4-dichlorosulfonyl-chlorobenzene (12.6 g) in acetone (100 ml) and cooled at -690C to effect reaction. After completion of the reaction, 28% ammonia water (25.0 ml) was added at -690C to the reaction mixture and the temperature of the mixture was then elevated up to 09C. The reaction liquid was diluted with water and then extracted with ethyl acetate. The organic phase was concentrated under reduced pressure to distill off the solvent. The residue was purified to obtain the title compound. Yield 9.1 g (80%); M.P. 148 C. Reference Example 3 Preparation of 2-sulfamyl-4-[-methyl- N-(a-methyltetrahydrofurfuryl)- sulfamyl]-chlorobenzene 2,4-Dichlorosulfonyl-chlorobenzene (9.3 g) was dissolved in ethyl acetate (65 ml) and the solution was cooled to -690C. Besides this, 2-methyltetrahydrofurfuryl-methylamine (2.6 g) were dissolved in ethyl acetate (15 ml), and the solution was added slowly to the aforesaid ethyl acetate solution cooled at -690C. After one hour, 28% ammonia water (16 ml) was slowly added dropwise to the reaction mixture at -690C. The temperature of the mixture was elevated up to 50C in about one hour. After completion of the reaction, the mixture was allowed to stand for phase separation and the aqueous layer was discarded. The organic layer was concentrated under reduced pressure until dryness. The caramel-like residue was dissolved in 3N-NaOH - solution (35 ml) and the insoluble matters were removed by extraction with toluene (40 ml). The aqueous phase was neutralized with 6N-HC1 solution (15 ml) and the white oily substance precipitated out was extracted with ethyl acetate (70 ml). The organic phase was decolorized, dried and concentrated until dryness. The residue thus obtained was then recrystallized from aqueous methanol (15 ml) whereby the title compound was obtained as a white crystalline powder in a yield of 6.9 g (908), M.P. 1490C. Reference Example 4 Preparation of 2-sulEamyl-4-tN- methyl-N-(a-methyltetrahydrofur furyl) -sulfamyli rchlorobenzene 2-Methyltetrahydrofurfuryl-methylamine (4.7 g) and triethylamine (4.9 g) were dissolved in tetrahydrofuran (16 ml). This solution was added to a solution which had been prepared by dissolving 2,4dichlorosulfonyl-chlorobenzene (17.0 g) in tetrahydrofuran (170 ml) and cooled at -690C to effect reaction. 28% Ammonia water (16.5 ml) was then added to the reaction liquid at -69 C. The temperature of the reaction mixture was allowed to rise up to -10 C and the mixture was extracted with ethyl acetate. The solvents were removed by distillation under reduced pressure and the residue was crystallized from methanol whereby the title compound was obtained as a white crystalline powder in a yield of 6.9 g (94%). NP. 149 C. Reference Example 5 Preparation of 2-sulfamyl-4- [N- (a- methyltetrahydrofurfuryl) -sulfamyl - chlorobenz ene N-Methyltetrahydrofurfurylamine (1.2 g) and triethylamine (1.2 g) were dissolved in ethyl acetate (5 ml), and this solution was added to a solution which had been prepared by dissolving 2, 4-dichlorosulfonyl-chlorobenzene (4.4 g) in ethyl acetate (25 ml) and cooled at -690C to effect reaction. 28% Ammonia water (8.5 ml) was added to the reaction liquid kept at the same temperature and the temperature of the mixture was then elevated up to 100C. The-aqueuus phase was.removed by phase separation and the organic phase was concentrated under reduced pressure to remove the solvent. The residue was purified by column chromatography whereby 2-sulfamyl-4-IN-(a-methyl- tetrahydrofurfuryl)-sulfamylI-chlorobenzene was obtained as a white crystalline powder in a yield of 2.8 g (80%). M.P. 162.40C. Elementary analysis as C12H17ClN205S2 (M.W. 368.85) Calc.: S, 17.38% ; Found: S, 17.12%

Claims: Claims: 1. A process for the preparation of 2-chlorosulfonyl 4- (N-substituted sulfamyl)-chlorobenzene compounds of the ceneral formula: EMI18.1 therein R is a hydrogen atom or a lower alkyl group, X is a 5- or 6-membered carbocyclic group which may contain an oxygen atom or atoms as ring-constituting members and nay be substituted on the ring by one or more lower alkyl groups, and n is O or 1, which. process comprises reacting a 2,4-dichiorosulfonyl- chlorobenzene of the formula: EMI18.2 with an amine of the general formula: R - NH - (CH2)n - X (III) wherein R, X and n are as defined above, in the presence of an acid-binding agent at a temperature of below lO0C. 2. A process as claimed in claim 1 wherein the temperature is maintained below OOC. 3. A process as claimed in claim 2 wherein the temperature is maintained below -40 C. 4. A process as claimed in any one of the preceding claims wherein the readtion between the 2,4-dichlorosulfonyl- chlorobenzene and the amine is carried out in the presence of a solvent inert to the reaction. 5. A process as claimed in claim 4 wherein the solvent is a ether, ester, ketone, amide or tertiary organic base. 6. A process as claimed in any one of the preceding claims wherein the acid-binding agent is an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal carbonate or bicarbonate, or a tertiary amine.

Inventors: MIYAMURA, SOUJI, NAKAHASHI, KAZUAKI, TAKEUCHI, TADASHI
Applicants: FUJI YAKUHIN KOGYO KABUSHIKI KAISHA
Application year: 1983
Main classification: C07D307
IPC codes: C07C67, C07C303, C07D307, C07C311, C07C301