JPH0212227B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel and stable haloprostacyclins and methods for their production. PGI ₂ is mainly released from the vascular endothelium, has the effect of inhibiting platelet aggregation, and has a blood pressure lowering effect based on the effect of relaxing smooth muscle (for example, JP-A-52-13619, JP-A-52- (Refer to Publication No. 95644, etc.) Therefore, it is an important drug that is expected to be applied to pharmaceuticals. (For example, B.
Samuelssons, Adv.in Prostaglandin and
Thromboxane Research.Vol.5, 7, 8Reven
Press, NY1980: JRVane et al. Prostacyclin,
(See Raven Press. NY1979: et al.) However, PGI ₂ has a half-life of activity of about several minutes at physiological pH, and there are problems with its stability as a pharmaceutical. Chemically, the instability of PGI ₂ is due to the fact that the vinyl ether structure containing the △ ⁵ double bond is easily hydrated and converted to 6-oxoprostaglandein, and in vivo, it is susceptible to dehydrogenase at position 15. This is thought to be due to the fact that it is quickly metabolized. On the other hand, the pharmacological effects of PGI ₂ are considered to be inferior in action selectivity as a pharmaceutical, such as the platelet aggregation inhibiting effect and the blood pressure lowering effect being almost equivalent in dosage. For this reason, PGI type ₂ is synthesized at home and abroad,
Considerable efforts have been made to compensate for these shortcomings (e.g., SM Roberts et al., Chemistry;
Biochemistry & Pharmacological Activity of
Prostaroids, Pergamon Press, Oxford;
1979). In particular, heretofore known methods for stabilizing enol ethers include: (1) 6,9-imino form (GLBundy 5,
(See Tetrahedron Letters, 1371 (1978)). (2) 6,9-thia form (KCNicolaow 5, J.
Amer.Chem.Soc. 100 , 2567 (1978): M.
Shibasaki et al., Tetrahedron Letters.559
(1978): Y. Arai et al., Chem. Letters, 1375
(1978)). (3) 6,9-carbo form (KCNicolaow et al.
Chem.Commun., 1067 (1978): K. Kogima et al.
Tetrahedron Letters, 3743 (1978): M.
Shibasaki et al., ibid , 433 (1979): Y. Konishi et al.
Chem. Letters, 1437 (1979): DRMortou et al.
J.Org.Chem. 44 , 2880 (1979)). (4) 5-oxo form (H. Nishiyama et al.
(See Tetrahedron Letters, 3481 (1979)). (5) 5-cyano form (see JP-A-54-81257). (6) 5-phenylthio compound (T. Toru et al.
Tetrahedron Letters, 2539 (1580)). etc. are known. The present inventors focused on this point, and as a result of intensive research to create a new stabilized PGI ₂ class, a stable new haloprostacyclin PGI ₂ with a bromine or chlorine atom introduced at the 5-position of PGI ₂ was created. The present invention was achieved by successfully obtaining a similar type. According to the present invention, the following formula [] [In the formula, R ¹ is a hydrogen atom or a lower alkyl group, R ² ,
R ³ represents a hydrogen atom or a protective group and may be the same or different. X represents a chlorine atom, a bromine atom or an iodine atom. ] Haloprostacyclin or R ¹ represented by
is a hydrogen atom, a pharmaceutically acceptable salt of the acid, and the following formula [] [In the formula, R ¹¹ represents a lower alkyl group, R ²¹ and R ³¹ represent a protecting group, and may be the same or different. ] Prostacyclin represented by the following formula []

【formula】

[Formula] or −O ^t Bu. ] The following formula [], which is characterized by reacting with a halogen or halogen derivative represented by, and optionally deprotecting and/or hydrolyzing. [In the formula, R ¹ , R ² , R ³ and X are the same as defined above. ] Haloprostacyclin or R ¹ represented by
is a hydrogen atom, a method for producing a pharmaceutically acceptable salt of the acid is provided. As far as the present inventors know, the haloprostacyclin represented by the above formula [] provided by the present invention is novel and has not been known until now, and is chemically unstable, which is a weak point of natural prostacyclins. has been improved. In other words, although natural prostacyclins are difficult to handle under normal neutral or slightly acidic conditions, this product is surprisingly stable under such conditions. . Furthermore, while the majority of conventionally known stabilized prostacyclins are those in which the vinyl ether structure of natural prostacyclins is chemically modified, the compound of the present invention has a natural vinyl ether structure. It also has the characteristic of retaining an endovinyl ether (△ ⁶ -PGI type ₁ ) structure, which is considered to be almost the same in terms of structure and biological activity. The new haloprostacyclins have pharmacological properties that are characteristic of prostacyclin.
For example, pharmaceuticals that are expected to have platelet aggregation inhibiting effects, blood pressure lowering effects, smooth muscle relaxing effects, etc., and are expected to have these physiological effects, such as therapeutic or preventive drugs for diseases based on thrombotic diseases, anti-asthmatic drugs, and anti-ulcer drugs. It is useful as a medicine, antihypertensive agent, etc. In the haloprostacyclines represented by the above formula [] provided by the present invention, R ¹ represents a hydrogen atom or a lower alkyl group, such as methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, 3- Examples include ethyl octyl group. Also, when R ¹ is a hydrogen atom,
Also provided herein are pharmaceutically acceptable non-toxic salts of the carboxyl group with an inorganic or organic base.
Examples of such bases include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium, and alkali metals such as sodium carbonate, sodium bicarbonate, and potassium carbonate. carbonates or bicarbonates, ammonia, ethanolamine, diethanolamine, and other organic bases. Among these R ¹ , preferred are methyl group,
Lower alkyl groups such as ethyl groups and sodium,
It is an alkali metal salt such as potassium, and methyl group and sodium salt are particularly preferred. Furthermore, R ₂ and R ³ in the above formula [] each independently represent a hydrogen atom or a hydroxyl group-protecting group. Examples of the protecting group for the hydroxyl group include those bonded by an ether bond or an ester bond. Such protective groups include those known in the art, such as those bonded with an ether bond such as tetrahydropyranyl, tetrahydrofuranyl, methyl, α-ethoxyethyl, and t-butyldimethylsilyl, and ester bonds such as acetyl and benzoyl groups. Examples include those combined with . Preferred examples of R ² and R ³ include a hydrogen atom, a t-butyldimethylsilyl group, and a tetrahydropyranyl group. In addition, X in the above formula [] represents a chlorine atom, a bromine atom, or an iodine atom, but the carbon atom with these halogen atoms (prostacyclin number 5
The steric configuration at (position) includes the (R)-configuration, the (S)-configuration, or a mixture thereof in any proportion. Preferred specific examples of such haloprostacyclines or pharmaceutically acceptable salts of the acid when R ¹ is a hydrogen atom include the following. 5-bromo-△ ⁶ -PGI ₁ methyl ester, 5-chloro-△ ⁶ -PGI ₁ methyl ester, 5-bromo-△ ⁶ -PGI ₁ methyl ester di-t-butyldimethylsilyl ether, 5-chloro-△ ⁶ - PGI ₁ methyl ester dit-butyldimethylsilyl ether, 5-bromo-△ ⁶ _-PGI monosodium, 5-chloro-△ ⁶ _-PGI monosodium. In producing the haloprostacyclin represented by the above formula [] provided by the present invention, the following formula [] [In the formula, R ¹¹ represents a lower alkyl group, R ²¹ and R ³¹ represent a protecting group, and may be the same or different. ] Prostacyclin represented by the following formula []

【formula】

[Formula] or −O ^t Bu. ] It can be produced by reacting with a halogen or halogen derivative represented by the following and optionally deprotecting and/or hydrolyzing. In the prostacyclin represented by the above formula [], R ¹¹ represents a lower alkyl group, and R ²¹ and R ³¹ represent a hydroxyl group-protecting group. They correspond to R ¹ , R ² , and R ³ of haloprostacyclines, and therefore, it is obvious that R ¹¹ is particularly a methyl group, and R ²¹ and R ³¹ are especially t-butyldimethylsilyl. or tetrahydropyranyl group is preferred. The halogen or halogen derivative represented by the above formula [] includes chlorine, bromine, iodine, N-
Examples include bromosuccinimide, N-chlorosuccinimide, N-bromophthalimide, N-chlorophthalimide, and the like. The amount of halogen or halogen derivative used is preferably 0.9 to 1.5 times the mole of the raw material compound []. Solvents used include halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, and 1,2-dichloroethane, ethers such as ethyl ether, tetrahydrofuran, and dioxane, and aromatic hydrocarbons such as benzene, toluene, xylene, and pyridine. , aliphatic hydrocarbons such as hexane, pentane, and cyclohexane, esters such as ethyl acetate, and aprotic polar solvents such as dimethylformamide, dimethylsulfoxide, and hexamethylphosphoformamide. Since the prostacyclin represented by the above formula [], which is a raw material, has instability in that the vinyl ether bond is destroyed by moisture, especially in an acidic atmosphere, the above reaction is carried out using, for example, triethylamine, triethylamine,
This is preferably carried out in the presence of a base such as pyridine, sodium bicarbonate, or sodium carbonate. The reaction temperature is -100°C to 80°C, preferably -80°C to 20°C. The reaction time varies depending on the reaction temperature, reagents used, amount of solvent, etc.
About 0.1 to 48 hours is preferable, and more preferably
It is about 0.1 to 20 hours. The reaction product thus obtained may be subjected to the purification step as it is or after being concentrated, but the product can also be obtained by extraction by a conventional method. The obtained product can be purified by means such as silica gel column chromatography, silica gel thin layer chromatography, florisil column chromatography, and high performance liquid chromatography. In some cases, about 0.01 to 1% of a base such as triethylamine may be added to the developing solvent used in these purification steps. The thus obtained haloprostacyclin can be prepared by hydrolysis of the 1-position ester group, if desired;
By deprotecting the protecting groups at positions 11 and 15, haloprostacyclines represented by the above formula [] can be obtained. Hydrolysis of the 1-position ester group can be obtained by alkaline hydrolysis using caustic soda, caustic potash, an aqueous calcium hydroxide solution, etc. as a base. In this case, an organic solvent such as ethanol, methanol, tetrahydrofuran, dioxane, etc. may be added to make the reaction proceed smoothly. The obtained reaction product can be concentrated or freeze-dried to obtain a salt of haloprostacycline, but it can also be used as a solution. The free carboxylic acid can be obtained by carefully neutralizing it with an acid such as sikolic acid, followed by extraction with a solvent such as ethyl acetate. Carboxylic acid salts can also be obtained by reacting the extracted carboxylic acid with a base. For example, ammonium salts can be obtained in a conventional manner by adding an equivalent or more amount of amines. On the other hand, in order to deprotect the protected hydroxyl groups at positions 11 and 15, the above-mentioned basic hydrolysis reaction can be used in the case of protecting groups for acyl groups, but in addition, for example, sodium methoxide, It is possible to use potassium methoxide, sodium ethoxide, etc. as a base and methanol, ethanol, etc. as a solvent, but especially in the case of silyl ether groups, fluorine-based reagents such as tetrabutylammonium, fluoride, cesium fluoride, etc. are used. is mentioned as a particularly preferred method. The haloprostacyclin obtained as described above is a stable prostacyclin analogue, and has, for example, platelet aggregation inhibiting action, smooth relaxing action,
It exhibits antihypertensive and antiulcer effects, and is effective against diseases corresponding to these physiological effects, such as Burgeer's disease, Raynaud's syndrome, angina pectoris, essential hypertension, deep static thrombosis, postoperative thrombosis, and endotoxin shock. It is a useful compound in the treatment of pulmonary hypertension, pulmonary embolism, DIC syndrome, thrombocytopenic purpura, gastric ulcer, septadenal ulcer, etc. It also shows the effect of suppressing cancer metastasis, and can also be used as a hapten to generate anti-hapten antibodies and measure the blood concentration of PGI ₂ . Examples will be described in more detail below. Example 1 30 mg of PGI ₂ methyl ester di-t-butyldimethylsilyl ether was dissolved in 0.4 ml of methylene chloride,
Add 6 mg of N-bromosuccinimide at 0°C,
Allowed time to react. The residue was then directly purified by column chromatography (silica gel, cyclohexane/ethyl acetate: 99:1 triethylamine (0.5%)) to obtain 7 mg of 5-bromo- ^Δ6 -PGI ₁ methyl ester. The properties of this product were as follows. NMR spectrum ( _CDCl3 ) δ: 3.69 (3H, s), 3.78-4.15 (2H, m), 4.3-4.9
(2H, m), 5.02 (1H, d, J=2Hz), 5.5
(2H, m). Mass spectrum (20eV): 674, 672 (M ⁺ ), 617, 615, 592, 577, 561,
535, 377. Example 2 15 mg (0.025 mmol) of PGI ₂ methyl ester di-t-butyldimethylsilyl ether and 11μ of triethylamine were dissolved in 0.6 ml of methylene chloride and heated at -74°C.
The mixture was cooled to 50°C, and a solution of bromine in methylene chloride (0.025 mmol) was added dropwise. Immediately after the completion of the dropwise addition, the mixture was poured into 1 ml of saturated sodium hydrogen chloride water, extracted with methylene chloride, dried, and treated in the same manner as in Example 1 to obtain 5 mg of 5-bromo-△ ₆ -PGI ₁ methyl ester di-t-butyldimethylsilyl ether. Ta. Example 3 22 mg of PGI ₂ methyl ester di-t-butyldimethylsilyl ether was dissolved in 0.5 ml of ethyl ether, and 4.5 mg of N-chlorosuccinimide was added under ice cooling. After stirring at the same temperature for 1 hour, the solvent was distilled off. It was immediately purified by florisil column chromatography (cyclohexane/ethyl acetate; 99:1, 0.5% triethylamine) to obtain 12 mg of 5-chloro- ^Δ6- PGI ₁ methyl ester di-t-butyldimethylsilyl ether. NMR ( _CDCl3 ) δ: 0.88 (21H, s), 1.1−2.6 (17H), 2.85−3.2
(1H, m), 3.66 (3H, s), 3.7−4.2 (2H, m),
4.40 (1H, m), 4.7-5.0 (1H, m), 5.00 (1H,
d, J = 3Hz), 5.50 (2H, m). Mass spectrum (70eV): 630, 628 (M ⁺ ), 592, 573, 571, 535. Example 4 5-chloro-△ ⁶ -PGI ₁ methyl ester di-t-
12 mg of butyldimethylsilyl ether was dissolved in 0.2 ml of tetrahydrofuran, and 0.1 ml of a solution of 12 mg of tetrabutylammonium fluoride in tetrahydrofuran was added under ice cooling, followed by stirring at room temperature for 4 hours. Purification was performed by florisil column chromatography (cyclohexane/ethyl acetate; 3:7, 0.5% triethylamine) to obtain 4 mg of the target product, 5-chloro-Δ ⁶ -PGI ₁ methyl ester. NMR spectrum ( _CDCl3 ) δ: 0.89 (3H, m), 1.1-2.5 (17H, m), 3.0-3.1
(1H, m), 3.68 (3H, s), 3.7−4.15 (2H,
m), 4.38 (1H, t, J=7Hz), 5.04 (1H, d,
J=3Hz), 4.8-5.2 (1H, m), 5.53 (2H,
m). Example 5 5-bromo-△ ⁶ -PGI ₁ methyl ester di-t-
7 mg of butyldimethylsilyl ether was dissolved in 0.2 ml of tetrahydrofuran, and 0.1 ml of a solution of 10 mg of tetrabutylammonium fluoride in tetrahydrofuran was added under ice cooling, followed by stirring at room temperature for 1 hour.
Treated in the same manner as in Example 4, 5-bromo-△ ⁶ -
PGI ₁ methyl ester was obtained. NMR spectrum ( _CDCl3 ) δ: 3.68 (3H, s), 3.75-4.2 (2H, m), 4.3-4.9
(2H, m), 5.04 (1H, d, J=2Hz), 5.5
(2H, m). Example 6 3 mg of 5-chloro-△ ⁶ -PGI ₁ methyl ester
The mixture was stirred in 0.1 ml of 1N caustic soda water and 0.1 ml of ethanol at room temperature for 2 hours to prepare an alkaline water-ethanol solution of 5-chloro- ^Δ6 _-PGI monosodium salt. Example 7 The in vitro platelet aggregation inhibitory effect of the haloprostacyclin of the present invention was assayed using rabbits. Specifically, blood was collected from the ear vein of a Japanese white male rabbit weighing 2.5 to 3.5 kg at a ratio of 9 parts blood to 1 part 3.8% trisodium citrate solution, and after centrifugation at 1000 rpm for 10 minutes, the upper layer was collected using PRP (platelet-rich plasma). ). The lower layer was further centrifuged at 2800 rpm for 10 minutes, and the upper layer, which was separated into two layers, was separated as PPP (platelet poor plasma). The platelet count was adjusted to 0 to 7×10 ⁵ /μl by dilution with PPP. Add 25 μl of test drug to 250 μl of PPP adjustment solution and preincubate at 37℃ for 2 minutes.
ADPIO μM (final) was added and the permeability was recorded using an aggregometer. The test drug was dissolved in ethanol to a concentration of 10 mg/ml, and then diluted sequentially with phosphate buffer (PH7.4) before use. The aggregation inhibition rate was determined using the following formula. Inhibition rate (%) = (1-T ^o _T ) x 100 T ₀ : Transmittance of (phosphate buffer added system) T : Permeability of test drug added system 5-Chloro assayed by the above method −△ ⁶
-The platelet aggregation inhibitory activity of PGI ₁ methyl ester is
IC ₅₀ =0.2 μg/ml, and after the test solution was left at room temperature for 4 hours, IC ₅₀ =2 μg/ml. on the other hand,
Initially, the IC ₅₀ of PGI ₂ was 0.002 μg/ml, but after being left at room temperature for 4 hours, the activity decreased to IC ₅₀ =0.5 μg/ml.

Claims (1)

[Claims] 1. The following formula [] [In the formula, R ¹ is a hydrogen atom or a lower alkyl group, R ² ,
R ³ represents a hydrogen atom or a trialkylsilyl group, and may be the same or different. X is a chlorine atom,
Represents a bromine atom or an iodine atom. ] Haloprostacyclin or R ¹ represented by
is a hydrogen atom, it is a pharmaceutically acceptable salt of the acid. 2. The haloprostacyclin of claim 1, wherein R ¹ is a methyl group. 3. Haloprostacyclin according to claim ¹ or 2, wherein R 2 and R ³ are t-butyldimethylsilyl groups. 4. The haloprostacyclin according to claim 1 or 2, wherein R ² and R ³ are both hydrogen atoms, or the pharmaceutically acceptable acid when R ¹ is a hydrogen atom. Shiru salt. 5. Haloprostacyclin acid according to any one of claims 1 to 4, wherein X is a chlorine atom or a bromine atom, or when R ¹ is a hydrogen atom, the acid is pharmaceutically acceptable. salt.