JPH0776588A - P-boronophenylalanine derivative, production thereof and intermediate compound for the same derivative - Google Patents

Abstract

PURPOSE:To obtain the novel derivative, having high selectivity for a melanotic cancer cell and useful for a neutron capture therapy by passing a specific compound through reaction thereof with ethanolamine and then debenzylating the resultant compound. CONSTITUTION:This p-boronophenylalanine derivative is expressed by formula I. Furthermore, this method for producing the p-bronophenylalanine derivative is to react a compound expressed by formula II (X is carbobenzyloxy) with N-methyldiethanolamine, then react the resultant compound with a compound expressed by formula III (R is benzyl), provide a compound expressed by formula IV and debenzylate the prepared compound expressed by formula IV. The debenzylation is carried out in the presence of, e.g., palladium hydroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to p-boronophenylalanine (hereinafter referred to as BPA) used for treating black skin cancer.
Abbreviated), a novel BPA derivative having improved water solubility, a method for producing the same and an intermediate compound of the derivative.

[0002]

2. Description of the Related Art In recent years, organoboron chemistry has been developed in a new form for the purpose of treating cancer by neutron capture therapy. Neutron capture therapy (NCT) is a method in which a boron 10 isotope is selectively taken into a cancer cell and is irradiated with low-energy neutrons to kill the cancer by a nuclear reaction occurring inside the cell.

As an organoboron compound used for such a purpose, BPA is used at a clinical level particularly for the treatment of black skin cancer (Y. Mori, A. Suzuki, K. Yosh).
ino, and H. Kakihana, Pigment Cell Res., 2, 273 (198
9)). BPA is a kind of phenylalanine or tyrosine that is strongly taken up into cells for the production of melanin. However, BPA has a low solubility in water,
Therefore, it is usually used as its hydrochloride or alkali metal salt. Recently, a monosaccharide complex of BPA has been used for improving water solubility. However, due to unstable chemical interactions between BPA and monosaccharides, BPA itself easily dissociates from the complex within the cell. Currently, water-soluble BP that can be used for the above-mentioned applications
The development of A analogs is desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide new BPA analogs with improved water solubility which can replace the conventional BPA analogs.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the water solubility of BPA is improved by converting the carboxyl group of BPA with amide polyglycerol. And has reached the present invention.

That is, the present invention provides the following formula (1)

[0007]

[Chemical 6] The present invention provides a novel BPA derivative represented by

The BPA derivative of the formula (1) is synthesized according to the following reaction scheme.

[0009]

[Chemical 7] That is, the hydroxyl group of 1,3-dibenzylglycerol (2) is converted to an amino group through tosylation, azide substitution and reduction treatment to obtain a compound of formula (3). On the other hand, the amino group of the starting material (±) -BPA is protected with a carbobenzyloxy (Cbz) group to obtain the compound of formula (4). Here, the direct condensation of compound (3) with compound (4) gives an unidentified polar substance due to the strong interaction between the amino group of compound (3) and the boron moiety of compound (4), In order to avoid this, the formula (5) in which the boron moiety of the compound (4) is protected by N-methyldiethanolamine is obtained, and the target compound of the formula (6) is obtained by reacting with the compound (3) in situ. obtain. The conversion of compound (6) to compound (1) can be carried out by converting compound (6)
The two benzyl moieties are treated in the presence of palladium hydroxide to debenzylate the compound (1) to give the hydrochloride salt, which is then treated with an ion exchange resin and high performance liquid chromatography (HP
The compound (1) is obtained by purification using LC).

B used as a raw material in the present invention
PA is from J. Am. Chem. Soc., 80, 83 by HR Snyder et al.
5 (1958).

The compound (2) can be easily synthesized from epichlorohydrin and benzyl alcohol.

Although the BPA derivative of the present invention has much improved water solubility as compared with untreated BPA, the present inventors have already reported in J. Org. Chem., 57, 435 (1992). By applying the published cascade technology, it is possible to control the water solubility of this BPA derivative in a wider range.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples.

Production Example 1 1,3-Dibenzylglycerol 4.1 under nitrogen atmosphere
54 g (15.25 mmol), p-methylbenzenesulfonyl chloride 4.362 g (22.88 mmo)
l) and dimethylaminopyridine 0.376 g (3.0
8 mmol) and a pyridine solution (6.5 ml) were stirred at room temperature for 17 hours, 3N-HCl was added after the reaction was completed, and the organic layer was extracted with ethyl ether. The ether layer was washed with a saturated aqueous sodium hydrogen carbonate solution and brine, and then anhydrous Mg
It was dried over SO ₄ and the solvent was concentrated off. 20 ml of a solution of the obtained crude product and 3.306 g (50.85 mmol) of NaN ₃ in dimethylformamide (DMF) was added to 100 ml.
The mixture was stirred at 0 ° C for 5 hours. After cooling the reaction solution to room temperature,
The organic layer was extracted with ethyl ether. The ether layer was washed with a saturated aqueous solution of sodium hydrogen carbonate and brine, and then dried with anhydrous M
It was dried over gSO ₄ and the solvent was concentrated off. The resulting crude product was applied to a silica gel column (“Kieselgel 6
0 "(trade name, manufactured by Merck), 70 to 230 mesh,
The developing solution was purified with n-hexane: ethyl acetate = 10: 1) to obtain 3.701 g (12.45 mmol) of an azide. The yield was 82%.

Production Example 2 3.701 g (12.45 g) of the azide obtained in Production Example 1
mmol) in 100 ml of dry ethyl ether solution,
LiAlH ₄ 0.951 g (25.06 mmol) was added, and the mixture was stirred at room temperature for 3 hours. After the reaction is complete, a small amount of 15%
An aqueous NaOH solution was added and the mixture was filtered. The obtained filtrate was dried over anhydrous MgSO ₄ , and the solvent was concentrated and removed to obtain 3.223 g (11.88 mmol) of the compound of formula (3). The yield was 95%.

Production Example 3 4.33 g (20.7 mmol) of 15% NaO BPA
4.5 ml of benzyloxycarbonyl chloride (Cbz-Cl) (31.5 mm
ol) and a 15% NaOH aqueous solution (6 ml) were alternately added dropwise, and after completion of the addition, the mixture was further stirred at room temperature for 5 hours. Transfer the reaction solution to a separating funnel, add ethyl ether and shake,
Excess Cbz-Cl was transferred to the organic layer and removed. Ethyl acetate and 12N-HCl were added to the aqueous layer at 0 ° C with stirring,
The reaction was extracted into the organic layer. After washing with brine, anhydrous MgS
It was dried over O ₄ and the solvent was concentrated off. 6.99 g (20.4 mmol) of the compound of formula (4) was obtained. Yield is 98%
Met.

Example 1 2.15 g (6.27) of the compound (4) obtained in Production Example 3
mmol) in 10 ml of DMF solution, 1.6 ml (13.9 mmol) of N-methyldiethanolamine was added,
Stir at room temperature for 10 minutes. Thereafter, 2.036 g (7.5 mmol) of the compound (3) obtained in Production Example 2 and 1.464 g (9.56 m) of N-hydroxybenzotriazole.
mol) and C ₂ H ₅ N = C = NCH ₂ CH ₂ CH ₂ NMe ₂
-HCl (1.529 g, 7.98 mmol) was added, and the mixture was stirred at room temperature overnight. The organic layer was extracted with ethyl acetate, washed with brine, dried over anhydrous MgSO ₄ , and the solvent was concentrated off.
The resulting crude product was applied to a silica gel column (developing solution: CHC
l ₃ : Ethanol = 50: 1) and the desired product 3.5
40 g (5.93 mmol) was obtained. The yield was 95%.

The compound obtained was analyzed by elemental analysis, IR and ¹ H.
-It was confirmed by NMR that the structure was of formula (6). The data of elemental analysis, IR and ¹ H-NMR are shown below.

[0019] IR (KBr): 3300, 3050, 2920, 2870, 1700, 166
0, 1620, 1540, 1460,1410, 1350, 1260, 1110, 1050,
^{1030, 740, 700 cm -1 1} H-NMR (CD 3 OD): 2.86ppm (dd, J = 9, 13.5H
z, 1H), 3.04 (dd, J = 6.5, 13.5Hz, 1H), 3.34 (dd, J = 5,
9Hz, 1H), 3.43 (dd, J = 5, 9Hz, 1H), 3.53 (d, J = 5Hz, 2
H), 4.17 (m, 1H), 4.39 (m, 1H), 4.35 ~ 4.44 (m, 4H),
4.96 (d, J = 12Hz, 1H), 5.03 (d, J = 12Hz, 1H), 7.3 (m, 17
H), 7.48 (d, J = 7.5Hz, 2H)

Next, 4.10 g (6.87 m) of compound (6)
(40 mol) of ethanol solution in 40 ml of Pd (OH) ₂ /
C (2.50 g) and concHCl (2 ml) were added, and H ₂
The mixture was stirred at room temperature under an atmosphere for 37 hours. After the reaction is completed, Pd
(OH) ₂ / C was filtered and the filtrate was concentrated. Ion exchange resin ("Dowex" (trade name, made by Dow Chemical Japan), 50W-X2, 50-100 mesh)
Elution with water removed HCl. Further, the product was eluted with 1N aqueous ammonia to obtain the desired product. The obtained crude product was treated with a column (“Shim-pack” (trade name, manufactured by Shimadzu Corporation),
PREP-ODS), HPLC (10% MeOH, 5 m
l / min. ), 1.088 g of the desired product (3.8
6 mmol) was obtained. The yield was 56%.

The compound obtained was analyzed by IR, ¹ H-NMR and
It was confirmed by ¹³ C-NMR that it had the structure of formula (1). The IR, ¹ H-NMR and ¹³ C-NMR data are shown below.

IR (neat): 3350, 3080, 2940, 1660, 16
10, 1540, 1420, 1350, 1320, 1260, 1090, 1050, 930,
^{880, 810cm -1 1 H-NMR} (D 2 O): δ7.47 (d, J = 7.0Hz, 2H, aroma
tic), 7.06 (d, J = 7.0Hz, 2H, aromatic), 3.67 (m, 1H,
-CONH-C H (CH ₂ OH) ₂ ), 3.63 (t, J = 7.0Hz, 1H, H ₂ NC H -CON
H-), 3.41 (d, J = 4.5Hz, 2H, -CH-C H ₂ OH), 3.24 (dd, J =
5.0, 11.0Hz, 1H, -CH-C H ₂ OH), 3.15 (dd, J = 6.0, 11.0H
z, 1H, -CH-C H ₂ OH), 2.83 (dd, J = 7.0, 13.5Hz, 1H, -C H
_{2 -C 6 H 4 -),} 2.79 (dd, J = 7.0, 13.5Hz, 1H, -C H 2 -C 6 H 4 -) 13 C-NMR (D 2 O): δ175.6, 138.8, 134.6 , 13
0.5, 129.9, 62.6, 61.6, 57.0, 52.9, 40.8

The water solubility value of the obtained compound (1) is 0.
66M (mol dm^-3), The water solubility of BPA
(7.66 × 10^-3It was about 100 times that of M). Also,
Compound (1) IC₅₀Since the value is high, the compound (1)
1.77 x 10^-2B-cultured in M even after 3 days
Lethal more than 50% of 16 human black cancer cells (B16)
I couldn't. Under similar culture conditions,
IC₅₀The value is 8.55 x 10 ^-3It was M. NCT Therapeutics
Based on the theory, the lower the cytotoxicity, the higher the boron content.
It is an excellent carrier for the position, and in this respect,
The low toxicity of compound (1) is preferred.

Next, the permeability of the compound (1) and BPA to B16 cells and TIG-1-20 human infant embryo cells (T20) was measured. The measurement was performed by mass spectrometry of residual boron atoms in cells using a high frequency inductively coupled plasma mass (ICP-MS) method. The results are shown in Table 1.

[0025]

[Table 1] 1) A boron compound (0.4 mmol) in Eagle-MEN medium (5 ml) was added to cultured cells (approximately 6.675 × 10 ⁵ ) in the same medium (15 ml) at 37 ° C., and 24
After a period of time, the medium is removed, and the remaining cells are quickly washed with PBS (-).
And washed with 60% HClO ₄ aqueous solution / 30% H ₂ O ₂ aqueous solution. The mixture is 70 until no solid is visible
Heated at ° C.

As can be seen from Table 1, the compound (1) of the present invention showed slightly higher permeability to B16 than BPA. On the other hand, the permeability of compound (1) to T20 was much lower than that of BPA. Compound (1) is T2
It has been found that it has 5 times more selectivity for B16 than for 0, while BPA has little selectivity.

[0027]

As described above, the formula (1) of the present invention is used.
The novel BPA derivative represented by
It is a compound useful for NCT therapy because it shows 0-fold water solubility and has high selectivity for B16 cells.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Yamamoto Aoba, Aoba-ku, Sendai, Miyagi Aoba Aoba, Tohoku University Faculty of Science

Claims (3)

[Claims] 1. The following formula (1): A p-boronophenylalanine derivative represented by: 2. The following formula (4): (In the formula, X represents a carbobenzyloxy group.)
Methyldiethanolamine is reacted and then the following formula (3): (In the formula, R represents a benzyl group.), Thereby reacting with the following formula (6): (Wherein X represents a carbobenzyloxy group and R represents a benzyl group), and the resulting compound of formula (6) is debenzylated to obtain the p-boronophenylalanine derivative of claim 1. Production method. 3. The following formula (6): (In the formula, X represents a carbobenzyloxy group, and R represents a benzyl group.)