JPS6411636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel camptothecin derivatives. To explain in more detail, the present invention includes:
general formula The present invention relates to a novel camptothecin derivative represented by [wherein, X is a nitro group, an amino group, an alkylamino group, or an acylamino group, and R is a hydrogen atom or an acyl group].

Camptothecin is extracted and isolated from deciduous trees such as Camptotheca acuminata Nyssaceae. It is an alkaloid that has a strong nucleic acid synthesis inhibitory effect, and its action is rapid and reversible. It is an antitumor substance with a unique mechanism of action that does not show cross-resistance with existing anticancer drugs. Although it has been recognized to have a strong anticancer effect on experimentally transplanted cancers such as murine leukemia L1210 and rat walker 256, its usefulness as a drug is naturally limited due to its toxic effects. The current situation is that

Therefore, attempts have been made to reduce toxicity while retaining anticancer activity by chemically converting camptothecin into other substances, that is, converting it into camptothecin derivatives.

However, camptothecin itself is poorly soluble in various organic solvents, and camptothecin has resistance to electrophilic substitution reactions due to the heterocycle it has in its chemical structure. However, there are various obstacles, and the reality is that it is not as easy to obtain new derivatives as planned on paper.

The present inventors previously investigated various modifications of the 10-position of camptothecin, and selectively modified the 10-position.
Although we succeeded in introducing functional groups related to oxygen atoms and sulfur atoms, it is difficult to introduce nitrogen atoms and halogen atoms using this method, and there are also problems to be solved in separation and purification of products. Because of the presence of nitrogen atoms and halogen atoms, research was conducted on methods for introducing nitrogen atoms and halogen atoms, and surprisingly, camptothecin was catalytically reduced in acetic acid or in a solvent such as dioxane-acetic acid using a platinum catalyst. The obtained 1-acyl-10-nitro-1, 1-acyl-10-nitro-1,
It has been found that various novel 10-substituted camptothecin derivatives represented by the above general formula can be obtained, which are used as starting materials for 2,6,7-tetrahydrocaptothecin.

The present invention has been made based on this knowledge.

The present invention will be explained in detail below. First, 1-acyl-10-nitro-1,2,6,
7-Tetrahydrocamptothecin can be produced by the following method.

The first reduction of the B-ring of camptothecin involves converting camptothecin in acetic acid or in dioxane-
Hydrogenation can be carried out efficiently by hydrogenation in hydrochloric acid in the presence of a platinum catalyst at normal pressure and room temperature. Next, the obtained 1,2,6,7-tetrahydrocamptothecin can be quantitatively converted into 1-acylated derivatives by treating it with a conventional acylating agent, and the obtained 1-acyl-1, 2,
When 6,7-tetrahydrocamptothecin is treated with nitric acid in concentrated sulfuric acid and nitrated, 1-acyl-10-nitro-1,2,6,7-tetrahydrocamptothecin is obtained in high yield.

This 1-acyl-10-nitro-1,2,6,7
- Using tetrahydrocamptothecin as a starting material, various novel 10-substituted camptothecins or 10-substituted tetrahydrocamptothecin derivatives can be produced by the following method.

10-Nitrocamptothecin is produced by hydrolyzing 1-acyl-10-nitro-1,2,6,7-tetrahydrocamptothecin in the presence of an acid or base and oxidizing the hydrolysis product (creating aromatic nuclei). is obtained. This oxidation (aromatic nucleation)
can be efficiently achieved by conventional oxidation methods such as DDQ oxidation, air oxidation or nitric acid oxidation. By such a method, 10-nitrocamptothecin, which cannot be obtained by nitration of camptothecin itself with sulfur/nitric acid, can be obtained at a yield of about 50%, calculated from camptothecin. Next, 10-nitro-1,2,6,7
- Quantitative conversion of the nitro group into the corresponding amino group by reducing or catalytic reduction of tetrahydrocamptothecin or its 1-acyl derivative and 10-nitrocamptothecin using a metal such as iron or tin in hydrochloric acid. can do. obtained
A 10-amino compound can be converted into a 10-acylamino compound or an alkylamino compound by acylating and alkylating its amino group. The 10-amino compound thus obtained can also be converted into a diazonium salt by diazonating the amino group, and the diazonium group can be further converted into various functional groups. For example, a 10-hydroxy substituted product can be obtained by diazotizing a 10-amino compound in an aqueous sulfuric acid solution and then heating, and a 10-methoxy substituted product can be obtained by treating a diazonium salt with methanol. I can do it. 10-Hydroxycamptothecin and 10-methoxycamptothecin obtained from 10-nitrocamptothecin are identified by comparing their various spectra with a specimen isolated from Kiju. The above 10-amino body,
10- by diazotization with hydrochloric acid or hydrobromic acid and treatment with cuprous chloride or cuprous bromide.
Chlorocamptothecin or 10-bromocamptothecin can be obtained.

According to the method of the present invention, starting material is camptothecin, which can be obtained relatively abundantly from plants such as Kiju, and various pharmacologically interesting 10-hydroxycamptothecins, such as 10-hydroxycamptothecin, which is originally a trace component. Positionally substituted products can be efficiently obtained via reduction of the B ring of camptothecin. The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 10-nitro-1,2,6,7-tetrahydrocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (500mg, 114m
mol) in a 20% aqueous sulfuric acid solution (30 ml) and boiled under reflux for 2 hours. The reaction mixture was diluted with ice water (200 ml) and extracted with chloroform (200 ml x 3).
The chloroform layer was dried with magnesium sulfate;
After filtration and drying under reduced pressure, 373 mg (82.3% yield) of the title compound is obtained as yellow crystals.
mp (decomposition) 274-275℃ [from CHCl ₃ ] IR ^KBr _nax νcm ^-1 : 3480, 1785, 1655, 1610, 1585,
1510, 1315, 1290, 1260.

MSm/e397 [M ⁺ ]C ₂₀ H ₁₉ N ₃ O ₆ = 397.

Example 2 1-acetyl-1,2,6,7-tetrahydro-10-nitrocamptothecin Camptothecin (hereinafter abbreviated as CPT) (500 mg, 1.44
mmol) in a mixed solvent of glacial acetic acid and dioxane (glacial acetic acid
50 ml + dioxane 50 ml), platinum oxide (100 mg) was added, and catalytic reduction was carried out at room temperature for 1 hour under normal pressure. The catalyst is removed and the solvent is distilled off under reduced pressure. The residue was dissolved in chloroform (200 ml), washed with 5% aqueous sodium bicarbonate solution (50 ml), the chloroform layer was separated, dried over MgSO ₄ and the solvent was distilled off under reduced pressure. The above operation was repeated 6 times, and the resulting 6 times of product was sprinkled on Celite and subjected to silica gel column chromatography (eluent: acetic acid ethyl ester) to obtain 1,2,6,7-tetrahydrocamptothecin. It will be done. Add 5 ml of pyridine to this
and 5 ml of acetic anhydride were added, heated at 60°C for 1 hour, pyridine and acetic anhydride were distilled off under reduced pressure, the residue was dissolved in chloroform (300 ml), and diluted with 5% aqueous hydrochloric acid solution, followed by 5% aqueous sodium hydrogen carbonate solution. After washing, the chloroform layer was dried with MgSO ₄ and evaporated under reduced pressure to give 1-acetyl-20-O-acetyl-
1,2,6,7-tetrahydrocamptothecin is obtained. Dissolve this in 50 ml of concentrated sulfuric acid, add fuming nitric acid (0.9 ml) to the solution under ice cooling, stir for 30 minutes, pour into ice water (approximately 300 ml), and extract with chloroform (200 ml x 3). After drying the chloroform extract with MgSO ₄ , it was distilled off under reduced pressure, sprinkled on Celite, and subjected to silica gel column chromatography (eluent: 1%
MeOH- _CHCl3 ), 1-acetyl-1,2,6,
7-tetrahydro-10-nitrocamptothecin (1.75 g, yield (from camptothecin) 46.2%)
is obtained.

Pale yellow-white needle crystals mp (decomposition) 271-273℃ [from AcOEt] NMR (in DMSO- _d6 ) δ: 0.63 (3H, t, J=7
Hz, -CH ₂ C H ₃ ), 1.63 (2H, q, J = 7Hz, -
CH2CH3 ₎ , _2.23 (3H,s,N-1 _- COCH3 ),
2.8~3.0 (2H, br, m), 3.4~3.8 (3H, br,
m), 4.0-4.2 (1H, br, m), 5.10 (2H, s,
C-17-H), 6.26 (1H, s, C-20-OH),
6.43 (1H, s, C-14-H), 7.53 (1H, d, J
=9Hz, C-12-H), 8.03(1H, dd, J=9
Hz, 2Hz, C-11-H), 8.22 (1H, d, J=
2Hz, C-9-H) IR ^KBr _nax cm ^-1 : 3450, 1755, 1660, 1585, 1525,
1375, 1345, 1300, 1155 MSm/e439 [M ⁺ ]C ₂₂ H ₂₁ N ₃ O ₇ = 439.

Example 3 Acetyl-10-amino-1,2,6,7-tetrahydrocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (500mg, 1.14m
mol), ethanol-dioxane (50ml-50
ml) and catalytically reduced using platinum oxide (250 mg) as a catalyst. The catalyst was removed, the solvent was dried under reduced pressure, and the residue was purified by silica gel column chromatography to obtain the title compound (450 mg,
96.7%).

mp145～148℃ MSm/z: 409 [M ⁺ ] 1H−NMR (in DMSO−d ₆ ) δppm: 0.70 (3H,
t, J=7Hz), 1.68 (2H, q, J=7Hz),
2.06 (3H, s), 2.55~2.7 (2H, m), 3.55~
3.75 (2H, m), 4.1~4.4 (3H, m), 5.13 (2H,
s), 6.24 (1H, s), 6.35-6.65 (4H, m).

IR ^KBr _nax νcm ^-1 : 3800, 2930, 1740, 1645, 1565,
1500, 1386, 1322, 1240, 1117.

Example 4 1-acetyl-10-acetylamino-1,2,
6,7-tetrahydrocamptothecin 1-acetyl-10-amino-1,2,6,7-
Tetrahydrocamptothecin (160mg, 0.39m
mol) in chloroform (10 ml), pyridine (1 ml) and acetic anhydride (0.1 ml, 0.98 mmol) were added, and the mixture was stirred at room temperature (8 h). The solvent was dried under reduced pressure and the residue was purified by silica gel column chromatography to obtain the title compound (155mg,
88.1%).

mp178～180℃ MSm/z: 451 [M ⁺ ] 1H−NHR (in DMSO−d ₆ ) δppm: (3H, t, J
= 7Hz), 1.98 (2H, q, J = 7Hz), 2.08 (3H,
s), 2.14 (3H, s), 2.65-2.8 (2H, m), 3.35
~3.60 (2H, m), 4.1 ~ 4.2 (1H, m), 5.16
(2H, s), 6.08 (1H, s), 6.48 (1H, d, J
=9Hz), 7.12-7.52 (3H, m).

IR ^KBr _nax νcm ^-1 : 3300, 2980, 1743, 1657, 1598,
1497, 1370, 1319, 1236, 1035.

Example 5 1-acetyl-10-dimethylamino-1,2,
6,7-tetrahydrocamptothecin 1-acetyl-10-amino-1,2,6,7-
Tetrahydrocamptothecin (160mg, 0.39m
mol) in chloroform (10 ml), methyl iodide (0.1 ml, 1.62 mmol) was added, and the mixture was boiled and refluxed (2 h). After washing the chloroform layer with 0.1N sodium hydroxide, it was dried under reduced pressure, and the residue was purified by silica gel column chromatography to obtain the title compound (130 mg, 76.0%).

mp191～194℃ Msm/z: 437 [M ⁺ ] 1H−NMR (in DMSO−d ₆ ) δppm: 0.68 (3H,
t, J=7Hz), 1.64 (2H, q, J=7Hz),
2.06 (3H, s), 2.50 (6H, s), 2.60~2.7 (2H,
m), 3.42-3.73 (2H, m), 4.1-4.2 (1H, m),
5.15 (2H, s), 6.28 (1H, s), 6.40-6.85
(4H, m).

IR ^KBr _nax νcm ^-1 : 3370, 2960, 1742, 1651, 1581,
1500, 1382, 1240, 1116.

Reference example 1 1,2,6,7-tetrahydrocamptothecin Camptothecin (500 mg, 1.43 mmol) was suspended in acetic acid (100 ml), platinum oxide (100 mg) was added,
Atmospheric catalytic reduction at room temperature (1.5 hours, absorbing approximately 140 ml of hydrogen). After removing the catalyst, the reaction mixture was dried under reduced pressure and the residue was dissolved in chloroform (200ml).
The chloroform layer was dried over magnesium sulfate, filtered, dried under reduced pressure, and subjected to silica gel (20 g) column chromatography. When purified with (chloroform), 285 mg (conversion rate) of the title compound was obtained as yellowish-white crystals (conversion rate:
56.3%, yield 76.7%). 113 mg (crude) of unreacted starting material was recovered.

mp (decomposition) 240-242℃ [from MeOH] IR ^KBr _nax νcm ^-1 : 3470, 1745, 1645, 1565, 1495,
1165, 1030.

Reference example 2 1,20-O-diacetyl-1,2,6,7-tetrahydrocamptothecin Camptothecin (500 mg, 1.43 mmol) was suspended in acetic acid (100 ml), platinum oxide (100 mg) was added,
Atmospheric catalytic reduction (1.5 hours at room temperature, absorbing approximately 140 ml of hydrogen). After removing the catalyst, the reaction mixture is dried under reduced pressure, dissolved in pyridine (5 ml), acetic anhydride (1 ml) is added and heated at 60-65°C for 1.5 hours. The reaction mixture was dried under reduced pressure and purified by silica gel column chromatography (2% acetone-chloroform) to yield 349 mg of the title compound.
(76.7% yield) and 149 mg (crude) of 20-O-acetylcamptothecin was recovered.

Colorless needle crystals mp > 280℃ [from C ₆ H ₆ ] NMR (in CDCl ₃ ) δ: 0.78 (3H, t, J = 7Hz,
−CH ₂ CH ₃ ), 2.18 (2H, m, − CH ₂ CH ₃ ), 2.20
(6H, s, 20− O −CO CH ₃ +N−1−CO CH
₃ ), 2.80 (2H, br, m, C-7 _- H2 ), 3.50
(2H, br, m, C-5- H ₂ ), 4.10 (1H, m,
C-6- H ), 5.02, 5.38 (1H, 1H, d×d,
J = 17Hz, C-17- H2 ), 7.20 ( _1H , s, C-
14- H ), 7.24 (1H, m, C-2- H ), 7.69
(1H, m), 8.10 (3H, m).

MSm/e432 [M ⁺ ]C ₂₄ H ₂₄ N ₂ O ₆ = 432.

Claims (1)

[Claims] 1. General formula A novel camptothecin derivative represented by [wherein, X is a nitro group, an amino group, an alkylamino group, or an acylamino group, and R is a hydrogen atom or an acyl group].