JPS6155517B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to new derivatives of the antibiotic tylosin. More specifically, the present invention provides the formula (In the formula, Ac is an acetyl group and Iva is an isovaleryl group.) 3''-acetyl-4''-isovaleryltylosin or a salt thereof. The above salts are pharmaceutically acceptable salts. Such suitable salts include hydrochloric acid, sulfuric acid,
Included are salts with inorganic acids such as phosphoric acid, and salts with organic acids such as acetic acid, propionic acid, tartaric acid, citric acid, succinic acid, malic acid, aspartic acid, and glutamic acid. Other non-toxic salts are also included. The above-mentioned novel compound [1] not only has antibacterial activity equivalent to that of the known antibiotic Tylosin, but also has macrolide-resistant group A bacteria (erythromycin, oleandomycin, 16-membered macrolides). (Antibiotic-resistant patient isolates) It also has strong antibacterial activity against macrolide-resistant group B and C bacteria. Moreover, it eliminates the bitter taste that is typical of Tylosin, making it useful as a syrup for children who cannot take tablets or capsules.
It is an antibiotic that is expected to have excellent clinical efficacy in treating infections. It is also useful as a therapeutic drug for animals and a feed additive. Tylosin has five hydroxyl groups at the 3-position, 2'-position, 3''-position, 4''-position and 4-position. 3 of these
It is said that the hydroxyl groups at the 2′, 2′, 4″, and 4th positions are easily acylated, and the 3″ hydroxyl group is inactive, so introducing an acyl group at the 3″ position into the above antibiotics Because highly reactive hydroxyl groups exist at positions other than the 3″ position, conventional methods for introducing acyl groups into the above antibiotics were not possible. The present inventor has discovered that the hydroxyl group at positions other than the 3″ position can be protected in advance with an acetyl group as a protecting group that is easily removed without being 3″-deacylated after the hydroxyl group at the 3″ position is acylated. At the same time, when introducing an acyl group into the hydroxyl group at the 3'' position, the acetyl group introduced into the hydroxyl group at the 4'' position was reacted with isovaleric anhydride under heating, resulting in acyl rearrangement at the 3'' and 4'' positions. The objective compound [1] of the present invention was obtained by reacting tylosin with acetic anhydride in the presence of an inorganic base to form the compound [1] of the present invention. A compound represented by the formula is obtained, and the compound [2] is reacted with isovaleric anhydride under heating in the presence of a tertiary organic amine in an inert organic solvent to obtain the formula A compound represented by is obtained, and the compound [3] is treated with ammonia in methanol or ethanol,
It can then be obtained by heat treatment in methanol which may contain water to eliminate the acetyl group at the 2' position. The introduction of protecting groups into the 3-, 2'-, and 4-position hydroxyl groups of tylosin is carried out by reacting acetic anhydride in the presence of an inorganic base. Examples of inorganic bases include alkali hydroxides such as potassium hydroxide, sodium hydroxide, alkali carbonates such as potassium carbonate, sodium carbonate, alkali hydrogen carbonates such as baking soda, etc.
Particularly preferred are alkali carbonates. The above protecting group introduction reaction is usually carried out at 30 to 100°C.
It is preferably carried out under heating at 40 to 60°C. Since the progress of the reaction can be monitored by thin layer chromatography using silica gel or the like, the reaction can be terminated as appropriate. Through the above reaction, an acetyl group is introduced into the aldehyde group at position 20, and the ring is closed via the carbon atom at position 18 and the oxygen atom at position 3, which not only protects the hydroxyl group at position 3 but also protects the hydroxyl group at position 2'. , the 4″-position and the 4-position are also acetylated at the same time.Protection at the 3- and 20-positions is excellent in selective reactions as a protecting group and has excellent stability, so it can be used as a protecting group for the hydroxyl group at the 3-position. It is an extremely excellent protecting group. To collect product [2] from the reaction solution, pour the reaction solution into water, adjust the pH of the aqueous layer to 8-10,
It can be collected by extraction with a suitable non-hydrophilic organic solvent. If further purification is required, it can be separated and purified by chromatography using an adsorbent such as silica gel, activated alumina, or adsorption resin and eluting with a suitable solvent, such as a benzene-acetone solvent. Next, compound [2] is 3″-acylated by reacting isovaleric anhydride with heating in the presence of a tertiary organic amine. Examples of the tertiary organic amine include: Pyridine-based compounds such as pyridine, picoline, and collidine are suitable, but are not limited thereto, and other known tertiary organic amines can also be selected as appropriate.Heating temperature is usually 50 to 120°C, preferably 80°C. The reaction time is carried out in the range of ~100°C.The reaction time varies mainly depending on the heating temperature, but since the reaction can be monitored by thin layer chromatography such as silica gel, the end point of the reaction can be appropriately determined by the disappearance of compound [2]. It is usually carried out for 1 to 200 hours. As a result of the above reaction, the acetyl group originally present at the 4″ position is transferred to the 3″ position, and an isovaleryl group is introduced at the 4″ position. be done. Compound [3] can be collected and purified from the reaction solution in the same manner as the step for obtaining compound [2] described above. Next, the protecting groups of compound [3] are removed. By first treating compound [3] with an ammonia-containing methanol or ethanol solution, the protecting groups at positions 3 and 20 and the protecting group at position 4 are removed. Will be detached. This elimination reaction proceeds satisfactorily at room temperature. Since the reaction can be monitored by thin layer chromatography using silica gel or the like, the reaction can be appropriately terminated after the disappearance of compound [3]. The product obtained by distilling off ammonia and alcohol from the reaction solution thus obtained is heat-treated in methanol which may contain water to remove the acetyl group at the 2' position. Heating is carried out under reflux of methanol. Since the reaction can be tracked by thin layer chromatography using silica gel or the like, the reaction may be terminated as appropriate. The product obtained by distilling methanol off from the reaction solution can be prepared using known methods for separating and purifying macrolide antibiotics, such as concentration, extraction, washing, dissolution, recrystallization, silica gel, activated alumina, adsorption resin, etc. By using a chromatography method using an adsorbent, the desired target compound [1]
can be separated and purified. Next, the results of measuring the antibacterial spectrum of the object compound [1] of the present invention, namely 3''-acetyl-4''-isovaleryltylosin, are listed in the following table.

[Table] Next, production examples of the present invention will be specifically explained with reference to Examples. Unless otherwise specified, Rf values in the examples were measured by thin layer chromatography (TLC) using the following carrier and developing solvent. Support: Silica gel 60 plate Art5721 manufactured by Merck & Co., Ltd. Developing solvent: Benzene-acetone (3:1) Example 10 g of tylosin is dissolved in 20 ml of acetic anhydride, 7 g of potassium carbonate is added, and the mixture is heated and stirred at 60° C. for 24 hours. Pour the reaction solution into 200ml of water and add aqueous ammonia.
After adjusting the pH to 9.5, extract twice with 100 ml of chloroform. The extract was dried over anhydrous magnesium sulfate and dried under reduced pressure to give 20・2′・4″・4-tetraacetyl-3・20-O-cyclo-tylosin [Rf=
0.49, Mass 1084 (MH ⁺ )] 10.2 g of crude product was obtained. This was dissolved in 50 ml of dry pyridine, 4 ml of isovaleric anhydride was added thereto, and the mixture was heated and stirred at 100°C for 110 hours. Pour the reaction solution into 400ml of water and add 200ml of chloroform.
Extract twice with ml. The extract was washed with water, dried over anhydrous magnesium sulfate, and dried under reduced pressure to give 20.2'.3".
4-tetraacetyl-3,20-O-cyclo-
4″-isovaleryltylosin [Rf=0.76,
Mass1168 (MH ⁺ )] crude product is obtained. This was subjected to silica gel column chromatography eluting with benzene-acetone (15:1), and the eluted fraction around Rf=0.76 was dried under reduced pressure to obtain 2.8 g of purified product. Dissolve this in 20 ml of methanol, add 20 ml of ammonia-saturated methanol, stir at room temperature for 5 hours, add 200 ml of water to the reaction solution, and extract twice with 100 ml of chloroform. The extract is dried over anhydrous magnesium sulfate and then dried under reduced pressure. Dissolve the residue in 100 ml of methanol and heat under reflux for 12 hours. The reaction solution was dried under reduced pressure, and the residue was mixed with benzene-acetone (9:1) and benzene-acetone (7:1).
Perform silica gel column chromatography to elute with
-Diacetyl-4"-isovaleryltylosin [Rf=0.39, Mass 1084 (MH ⁺ )] 320 mg is obtained. The latter elution fraction is dried under reduced pressure to give the desired 3"-acetyl-4"-isovaleryltylosin 1.2 Obtain g. Rf=0.23 Mass1042 (MH ⁺ )

Claims (1)

[Claims] 1 3″-acetyl-4″-isovaleryltylosin or a salt thereof.