CS202571B2 - Process for preparing selective protected derivative of kanamycine a or kanamicine b - Google Patents

Description

The invention relates to a process for the preparation of a selectively protected kanamycin A or kanamycin B derivative.

In particular, the invention relates to a process for the preparation of N-protected derivatives of the type mentioned.

Examples of 1-N-substituted kianamycin derivatives are given in U.S. Pat. No. 5,638,949; 195,713, other derivatives are known compounds, for example, N- (4-amino-2-hydroxybutyryl) -canamycin A (BB-K8) described in British Patent No. 1,401,221. In the manufacture of these compounds from kanamycin, which is commercially available, it is desirable to protect some amino groups at a position different from position 1 of all these amino groups, and then substitution can be made almost exclusively at the amino group at position 1. This also facilitates the isolation of the resulting 1-N-suibstituted product.

Accordingly, the present invention provides a process for the preparation of a selectively protected kanamycin A or kanamycin B derivative of the formula II

CH.NHR ³ ηο- ^ ΛΛο

(II) where

R ² represents hydrogen or benzyl,

R ³ is an acetyl or trifluoroacetyl group,

R ⁴ represents a hydroxyl group or Group ^Nu NHR ^3, wherein

R ³ is as defined above, characterized in that it consists in .reakci triflnoracetát kanamycin A, kanamycin B or 3-N-be'nzylkanamyeinu A, 1,3,6 ', 3 "-tetra-N-benzyloxycarbonylkanamycin A, 1,3 ', 6', 3 '-penta-N-benzyloxycarbonylkanamycin B or 3-N-benzyl-1,6', 3'-tri-N-benzyloxycarbonalkanimycin A of formula IV

wherein (R ² is a hydrogen atom, a benzyl or a hydrogen atom)

b.enzyloxycarbonyl, (R ³ ) 'means a hydrogen atom or benzyloxycarbonyl, and (R ⁴ ) a fused hydroxy or NH group (R ³ '', provided that each of the groups (R ³ )''has the same meaning, with acetylation or trifluoroacetylation. The resulting O-acetyl derivative is neutralized with a base at room temperature, then the remaining O-acyl groups are removed by hydrolysis and the selectively N-protected derivative of formula II is isolated.

This process is particularly effective for producing those compounds wherein R ⁴ is a hydroxyl group and R ³ is a trifluoroacetyl group. In this case, cananaimycin A or 3-N-benzylcanamycin A is dissolved in trifluoroacetic acid and reacted with trifluoroacetic anhydride at 0 ° C. The reaction is complete after several hours at 0 ° C and then the resulting per-O-trifluoroacetylalkanamycin derivative and its trifluoroacetate salt can be isolated by evaporation of the solvent in vacuo. The product is dissolved in an inert organic solvent, preferably tetrahydrofuran, and neutralized with a base such as sodium carbonate. or potassium. It has been found that under these conditions, the transfer of the 0 N acyl group can be carried out very quickly, the reaction being completed in 20 mm at room temperature. Remaining O-trifluoroacetyl groups are removed in a conventional manner, for example by methanolysis to give the 3 ', 6'-di-N-trifluoroacetyl derivative can be isolated by evaporation of the solvent and purified by conventional column chromatography.

Alternatively, kanamycin A or 3-N-benzylkanamycin A is first reacted with a reagent to introduce a removable amino-protecting group. Suitable groups are, for example, t-butaloxycarbonyl or benzyloxycarbonyl. The product thus protected is then subjected to O-acylation in a known manner, for example by treatment with an anhydride or acid chloride such as acetic anhydride in pyridine or with an alkyl chloroformate, after which the blocking groups are removed again, for example by removal of the t-tyloxycarbonyl group. trifluoroacetic acid and benzyloxycarbonyl groups by catalytic hydrogenolysis. The displacement of the O → N acyl groups is then carried out in the same manner as above and the remaining O-acyl groups are removed and the product isolated as described.

The process according to the invention can also be carried out using kanamycin B, in which case the acyl group is transferred from the 3'-hydroxyl group to the adjacent 2'-amino group to give the tri-N-acylated intermediate.

The compounds of formula II may exist in several forms. The substituents may usually be equatorial to the ring. In addition, the glylcosidic bond between the hexopyranosyl ring and the 2-desoxystreptoamine ring is usually in the X position.

In the following examples, the preparation of 3-N-benzylcanamycin A is described in Example 1.

The chromatography was performed on a thin layer of silica using the solvent system. Spots were developed after drying the plates by spraying with 5% t-butyl hypochlorite in cyclohexain, drying the plates at 100 ° C for 10 minutes in a ventilated oven, cooling and then spraying with a solution of potassium iodide and starch.

Temperatures are given in degrees Celsius, "Amberliite" is a proprietary plaque designating an ion exchange resin of a polystyrene base crosslinked with 3 to 5% divinylbenzerium and containing sulfonic acid residues introduced by sulfonation.

Example 1

Dissolve 24.3 g (0.03 mol) of kanamycin A in the form of sulphate in 150 ml of water and adjust the pH to 6 by adding dropwise 5-N-hydrochloric acid dropwise. Sodium cyanoborohydride (1.95 g, 0.03 mol) was added and the mixture was cooled and stirred at 0 ° C while slowly adding a solution of 3.61 g (0.33 mol) of benzaldehyde in 15 min. ml of methane. The mixture was allowed to warm to room temperature. After 16 hours, the pH of the solution was adjusted to 5.5 by the addition of 1 N hydrochloric acid, and the solution was filtered and applied to an ion exchange resin column (Amiberlilt CG-50) in NH 4 Morim. The column is eluted with water and then gradually increasing the amount of ammonia in water, the ammonia concentration increases in the range of 0 to 0.7 N, thereby obtaining 3-N-benzylkanamycin A as the main product together with a small amount of 1-N-benzyl derivative. is 5.0 g, yield, 28%, Rf 0.44 in 4: 1: 2 methanol: chloroform: 17% ammonium hydroxide. Pure kanamycin A gave an _Rf value of 0.15.

A sample of the product can be converted to the volatile tetra-N-acetylhepta-O-trimethylsilyl derivative by treatment with acetic anhydride in methanol at room temperature for 24 hours followed by reaction with 2: 1 hexamethyldisilazane and trimethylchlorosilane at room temperature for 24 hours, im / e for C54H106N4O15Si7: calcd 1246 and found 1246.

The position of the substituent was confirmed by the following sequence of reactions:

(a) treatment with 3-t-butyloxycarbonyl group together with a benzyl group as confirmed by NMR spectrum, (b) hydrogenation to remove the benzyl group;

c) acylation can be carried out with N - [(S) -4-benzyloxycarbonyla, mino-2-hydroxybutyryloxyjsuccinimide and the dj N-protecting group can be removed by hydrogenation followed by trifluoroacetic acid to give 3-N- ( S) -4-amino-2-hydroxybutyryl] cyanimycin A (BB-K29) identical to the sample obtained by the method of Naito et al. (J. Antibiotics, 1973, 26, 297).

Example 2

5.0 ml of trifluoroacetic anhydride are slowly added to a solution of 1.0 g of kanamycin A, in 40 ml of trifluoroacetic acid at 0 ^DEG C., with stirring, and the solution is allowed to stand at 0-4 DEG C. for 20 hours. The solvent is then removed in vacuo and the residue is treated with 10 ml of toluene and evaporated to dryness. The trifluoroacetate salt is mixed with anhydrous terahydrofuran and slowly neutralized by adding an excess suspension of anhydrous potassium carbonate in tetrahydrofuran while stirring. The mixture was stirred at room temperature for 20 minutes and the suspension was then filtered and the filtrate was evaporated to dryness. The product is mixed with 20 ml of methanol and not allowed to stand at room temperature for 30 minutes. The solvent 'was removed under reduced pressure and the residue chromatographed on silica, eluting with a variable concentration .chloroformu first with methanol 3: 1 mixture of chloroform, methanol and _170/0 ammonium hydroxide in a ratio of 8: 4: 1 to give 0.52 g of 3 ', 6'-di-N-trifluoroacetylkanamycin A hydrate as a white hygroscopic substance. R _f = 0.7 when using methanol, chloroform, 17 ^Io / o ammonium hydroxide 4: 1: 1, kanasmycin A has R _f 0.05. i> _{c = 0} 1665 cm ^-1 .

A sample of the product was converted to the volatile di-N-aceitylhepta-O-trimethylsilyl derivative according to Example 1. m / e for C47H94N4O15F6Si7: calcd 1264, found 1264.

Example 1 a d 3

0.7 ml (5 mmol) of trifluoroacetic anhydride was added slowly to .rozteku 0.23 g (0.4 mmol) of 3-N-benzylkanamycin A in 15 mL of trifluoroacetic acid at 0 DEG C. The solution ^Q was kept for 20 hours at -4 ° C. The solvent was evaporated and the residue was treated with 10 ml of toluene and evaporated to dryness. The product was dissolved in 20 mL of tetrahydrofuran and added slowly to a suspension of excess potassium carbonate in tetrahydrofuran while stirring. The suspension is allowed to stand at room temperature for 30 minutes, filtered and the filtrate is evaporated to dryness under reduced pressure. The residue is treated with 20 ml of methanol and allowed to stand at room temperature for 30 minutes. The solvent was evaporated in vacuo to give 3-N-benzyl-3 ', 6'-di-trifluoroacetic .N- ^i, A o racetylka.namycin _Rf 0.5 using methanol, chloroform, 8% ammonium hydroxide - in a ratio of 4: 1: 0.1; 3-N-benzyl, kanamycin A has an _{Rf of} 0.01.

Example 4

A. A solution of 189.4 g, 3,3 ', 6 ' -tetra-N ' -benzyloxyphenebonylcanaimycin A (Bull. Chem. Soc. Japan, 1965, 36, 1181) in 568 ml of pyridine and 189 ml of acetic anhydride is stirred. overnight at room temperature and then poured into 1.9 liters of water. The aqueous solution was extracted with chloroform (1 x 1.8 L and 1 x 1.0 L) and the organic extract was evaporated to dryness under reduced pressure. Mixing the residue with ether yielded 224.8 g of penta-O-acetyl-1,3 ', 3', 6'-tetra-N-benzyloxycarbonylkanamycin A, which was filtered off and dried in vacuo. Melting point: 203 DEG 2i29 "C, R _f = 0.55, chloroform, δ = 1.8 to 2.05 (15 proton multiplet, 5 acetyl groups) and 7.4 (20 proton singlet, 4 phenyl groups) .

B. A solution of 53 g of penta-O-acetyl-1,3,3 ', 6'-tetra-N-benzyloxycarbonylcan, myicin A in 260 ml of ethyl acetate containing 260 ml of glacial acetic acid was hydrogenated using 5% palladium on charcoal. in a total amount of 15 g at 60 ° C and 446 kPa pressure for 7 hours. The solution was filtered and the filtrate was evaporated to dryness under reduced pressure. The residue was treated with ether and the resulting penta-O-acetylcanamycin (32.9 g) was dried in vacuo. The product had a melting point of 97 to 105 ° C., in R 0,0 'mixture of chloroform and ethanol denatured with methanol in a ratio of 12: 1 compared with the R _f starting material 0.55. The total absence of aromatic protons was demonstrated at proton magnetic resonance.

C. A solution of 139.2 g of penta-O-acetylkanamycin A in 1.4 L of ammonia saturated methanol was allowed to stand overnight at room temperature and then evaporated to dryness under reduced pressure. The residue is dissolved in 140 ml of methanol and the crude product is precipitated with 2.5 l of chloroform, filtered and evaporated in vacuo. The crude product is slurried in 400 ml of methanol-denatured industrial alcohol and 91.9 g of the resulting 3 ', 6'-di-N-acetyl-akanamycin A are collected by filtration, washed with ether and dried in vacuo. The product had a melting point of 150 ^DEG- 180 ^DEG C., Rf 0.77 in imethanol, and 0.880 ammonium hydroxide in a 1: 1 ratio. The NMR and proton spectra were fully consistent with the proposed structure.

Example 5

3.6 ml of trifluoroacetic anhydride is slowly added with stirring to a solution of 960 mg (2 mmol) of kanamycin B in 50 ml of trifluoroacetic acid at 0 ° C. The solution was allowed to stand at 0-4 ° C for 20 hours. The solvent was evaporated under reduced pressure and the residue was treated with 10 ml of toluene and evaporated to dryness. The trifluoroacetate salt was dissolved in 30 ml of tetrahydrofuran and the solution was slowly added with stirring to an excess of triethylamine in tetrahydrofuran. The solution was allowed to stand at room temperature for minutes, then the solvent was evaporated under reduced pressure. The residue was dissolved in methanol to hydrolyze the remaining O-trifluoroacetyl group and after an additional 30 minutes at room temperature the solvent was evaporated under reduced pressure and the product was chromatographed on silica using a 20: 1 mixture of chloroform and imethaammonium to elute the column. 10: 1, thereby obtaining ammonium hydroxide up to a final 3: 1 mixture of chloroform, methanol and 17% n-hydroxide with an increasing proportion of 45 '2 mg (' 29%) of 2 ', 3', 6'-tri-N-trifluoro acetylkanamycin B in the form of a glassy mass. The product has an R _of 0.70 in methanol, chloroform, 8% ammonium hydroxide 4: 1: 0.1, kanamycin B, having R _f 0.0.

The structure of the product was confirmed by the following sequence of reactions:

(a) acetylation was performed with acetic anhydride in methanol for 20 hours at room temperature followed by treatment with 1 N ammonium hydroxide for 18 hours to remove the trifluoroacetyl group to give a product containing two acetyl groups, m / e for C22H41N5O12: calcd. 568;

b) treatment with acetic anhydride containing deuterium in methanol at room temperature for 24 hours followed by reaction with a 2: 1 mixture of hexamethyldisilazane and trimethylchlorosilane at room temperature for 24 hours yielded a volatile tri-N-deuteroacetyl-dl-N-acetylhexa- O-triimethylsilyl derivative, m / e for C46H86N5O15D9Si6: calculated 1134, found 1134. Diacetylation occurred on the 2-desoxystreptamine ring, indicating that the trifluoroacetylation was initially performed at the 2 ', 3' and 6 'positions of kanamycin B.

Claims (3)

SUBJECT A process for the preparation of a selectively protected kanamycin A or kanamycin B derivative of the general formula II (II) INVENTION where R ² represents hydrogen or benzyl, R ³ is an acetyl or trifluoroacetyl group, R ⁴ represents a hydroxyl group or an N'HR ³ group wherein ¹ R ³ is as defined above, characterized by reacting trifluoroacetate kanamycin A, kanamycin B or 3-N-benzylkanamycin A, l, 3,6 ', 3 "-tetra-N-benzyloxycarbonylkanamycin A, 1.3 2 ', 6', 3 '-penta-N-benzyloxycarbonylnylkanamycin B or 3-N-benzyl-1,6', 3'-tri-N-benzyloxycarbonylkanamycin A of the general formula IV wherein (R ² represents a hydrogen atom, benzyl or benzyloxycarbonyl, (R ³ '' is hydrogen or benzyloxycarbonyl, and (R ⁴ ) 'means hydroxy or NH' (R ³ ) ', provided that each of (R ³ )' has the same meaning, by acetylation or trifluoroacetylation reagent, catalytic hydrogenation removes any benzyloxycarbonyl groups present, the resulting O-acetylated derivative is neutralized with a base at room temperature, then the remaining O-acyl groups are removed by hydrolysis and the selectively N-protected derivative of formula II is isolated. 2. A process according to claim 1, wherein the trifluoroacetic acid salt of kanamycin A, kanamycin B or 3-N-benzylkanamycin A is acylated with trifluoroacetic anhydride. 3. A process according to claim 1, wherein acetic anhydride is used as acetylating agent.