JPS636071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides novel 10-nitro-1,2,6,7
- A method for producing a tetrahydrocamptothecin derivative. More specifically, the present invention involves the catalytic reduction of camptothecin to obtain 1, 2, 6,
7-tetrahydrocamptothecin is treated with an acylating agent, and the resulting acylated product is treated with sulfuric acid and nitric acid to introduce a nitro group at the 10-position, and the acyl present in the resulting 10-nitro-camptothecin derivative is a one-carrier system, characterized in that the group is optionally removed by hydrolysis; The present invention provides a method for producing a 10-nitro-1,2,6,7-tetrahydrocamptothecin derivative represented by the formula (wherein R is a hydrogen atom or an acyl group).

Camptothecin is an alkaloid extracted and isolated from plants such as Camptothecaacuminata Nyssaceae, and has a strong effect of inhibiting nucleic acid synthesis.Its action is rapid and reversible, and has cross-resistance with existing anticancer drugs. It is an antitumor substance with a unique mechanism of action that does not show
Although it has been recognized to have a strong anticancer effect on experimentally transplanted cancers such as 256 sarcoma, its usefulness as a drug is naturally limited due to its toxic effects.

Therefore, attempts have been made to chemically convert camptothecin into other substances, that is, to convert it into camptothecin derivatives, thereby reducing toxicity while retaining anticancer activity.

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 had previously succeeded in selectively introducing a functional group related to an oxygen atom or an ionic atom into the 10th position of camptothecin as a starting material (see Japanese Patent Application No. 138411/1983). ), depending on the method, it is difficult to introduce nitrogen atoms and halogen atoms, and furthermore, there are problems to be solved regarding product separation, purification, etc.
As a result of repeated research on the method of introducing nitrogen atoms and halogen atoms into positions, we found that 1,2,6,7-tetrahydrocamptothecin obtained by catalytic reduction of camptothecin was treated with an acylating agent, and the resulting acylated product was treated with sulfuric acid. It was discovered that a nitrated derivative at position 10 can be obtained by nitration using nitric acid. The present invention has been made based on this knowledge.

The present invention will be explained in detail below.

In the method of the present invention, the reduction of camptothecin B ring, which is the first reaction, is carried out using acetic acid, dioxane-acetic acid, dioxane-hydrochloric acid, etc. as a solvent, and under normal pressure in the presence of a catalyst for catalytic reduction such as a platinum catalyst. , can be efficiently carried out by hydrogenation at room temperature. Obtained 1, 2, 6,
7-tetrahydrocamptothecin can then be treated with an acylating agent to introduce an acyl group into its 1-position. Then, the obtained 1-
When acyl-1,2,6,7-tetrahydrocamptothecin is nitrated with nitric acid in concentrated sulfuric acid, 1
-Acyl-10-nitro-1,2,6,7-tetrahydrocamptothecin is selectively obtained in good yield. This 1-acyl-10-nitro-1.2.
The N-acyl group of 6,7-tetrahydrocamptothecin can be removed by hydrolysis in the presence of an acid or a base to yield 10-nitro-1,2,6,7-tetrahydrocamptothecin.

The thus obtained 1 expressed by the above general formula
-Acyl-10-nitro-1,2,6,7-tetrahydrocamptothecin can be converted into other 10-substituted camptothecin or 10-substituted-1,2,6,7-tetrahydrocamptothecin by converting its nitro group into various substituents. It is an important intermediate for the synthesis of various 10-substituted camptothecin derivatives because it can be derived into -tetrahydrocamptothecin derivatives.

For example, 10-nitro-camptothecin can be obtained by aromatizing the nucleus by oxidizing 10-nitro-1,2,6,7-tetrahydrocamptothecin, but this oxidation (aromatization) reaction
This can be efficiently achieved by methods such as oxidation, air oxidation, or nitric acid oxidation. Nitration at position 10 using this method cannot be achieved by nitration of camptothecin itself with sulfuric acid or nitric acid.
The 10-nitro compound can be obtained using camptothecin as a starting material in a yield of about 50% based on the amount of camptothecin.

10-nitro-1・2・obtained by the present invention
6,7-tetrahydrocamptothecin or 1
The -acyl form and 10-nitrocamptothecin can be converted into various 10-substituted camptothecin derivatives as described below. That is, for example, these compounds can be subjected to reduction or catalytic reduction with metals such as iron or tin in hydrochloric acid to convert the nitro group into an amino group to quantitatively obtain the corresponding 10-amino form. Can be done. These 10-amino bodies can be converted into 10-acylamino bodies or 10-alkylamino bodies by acylating or alkylating the amino group. The amino group of this 10-amino compound can also be converted into various other functional groups by converting it into a diazonium salt. For example, a 10-hydroxy substituted product can be obtained by diazotizing this 10-amino compound in an aqueous sulfuric acid solution and then heating, and a 10-methoxy substituted product can be obtained by treating the above diazonium salt with methanol. . 10-Hydroxy-camptothecin and 10-methoxycamptothecin obtained from 10-nitrocamptothecin were identified by comparing various spectra with a standard product isolated from Kiki. Furthermore, 10-chlorocamptothecin or 10-bromocamptothecin can be obtained by diazotizing the above 10-amino compound in hydrochloric acid or hydrobromic acid and then treating with cuprous chloride or cuprous bromide. can.

Examples of the present invention are listed below, but the present invention is not limited to these Examples.

Example 1 (a) Production of 1,2,6,7-tetrahydrocamptothecin Camptothecin (500 mg, 1.43 mmol) was suspended in acetic acid (100 ml), platinum oxide (100 mg) was added, and catalytic reduction was carried out at room temperature under normal pressure ( 1.5 hours, about 140
ml of hydrogen). After removing the catalyst, the reaction mixture was dried under reduced pressure, the residue was dissolved in chloroform (200 ml), 5% aqueous sodium bicarbonate solution (100 ml), and then saturated brine (100 ml).
ml), and the chloroform layer was dried over magnesium sulfate, filtered, dried under reduced pressure, and purified by silica gel (20 g) column chromatography (chloroform) to obtain the title compound with the following physical properties as yellow-white crystals. , 285mg (conversion rate
56.3%, yield 76.7%). At this time, 113 mg (crude) of unreacted raw material was recovered.

mp (dec.) 240-242℃ (from methanol) IR ^KBr _nax νcm ^-1 : 3470, 1745, 1645, 1565, 1495,
1165, 1030 (b) 1,20-O-diacetyl-1,2,6,7-
Production of tetrahydrocamptothecin Camptothecin (500 mg, 1.43 mmol) was suspended in acetic acid (100 ml), platinum oxide (100 mg) was added, and catalytic reduction was carried out at normal pressure (at room temperature for 1.5 hours, about 140 mmol).
ml of hydrogen). After removing the catalyst, the reaction mixture was dried under reduced pressure, dissolved in pyridine (5 ml), acetic anhydride (1 ml) was added, and the mixture was heated at 60-65°C.
Warm for 1.5 hours. The reaction mixture was dried under reduced pressure,
Purification by silica gel column chromatography (2% acetone-chloroform) yields 349 mg (76.7% yield) of the title compound having the following physical properties. At this time, 149 mg (crude) of 20-0-acetylcamptothecin was recovered.

Colorless needle crystals.

mp > 280℃ (from C ₆ H ₆ ) NMR (in CDCl ₃ ) δ: 0.78 (3H, t, J = 7
Hz, -CH ₂ CH ₃ ), 2.18 (2H, m, -CH ₂ CH ₃ ),
2.20 (6H, s, 20−O−COCH ₃ +N−1−
COCH ₃ ), 2.80 (2H, br m, C-7-H ₂ ),
3.50 (2H, br m, C-5-H ₂ ), 4.10 (1H,
m, C-6-H), 5.02, 5.38 (1H, 1H, d
x d, J = 17Hz, C-17-H ₂ ), 7.20
(1H, s, C-14-H), 7.24 (1H, m, C
-2-H), 7.69 (1H, m), 8.10 (3H, m) MS: m/e432 [M ⁺ ] (as C ₂₄ H ₂₄ N ₂ O ₆ = 432) (c) 1-acetyl-1. Production of 2,6,7-tetrahydro-10-nitrocamptothecin Camptothecin (500 mg, 1.44 mmol) was suspended in a mixed solvent of glacial acetic acid and dioxane (50 ml of glacial acetic acid and 50 ml of dioxane), and platinum oxide (100 mg) was added to this. , Catalytic reduction is carried out at room temperature and atmospheric pressure for 1 hour. Then, after removing the catalyst, 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 is repeated 6 times, and the resulting 6 times of product is sprinkled on Celite and subjected to silica gel column chromatography (eluent: acetic acid ethyl ester) to obtain 1,2,6,7-tetrahydrocamptothecin. . 5 ml of pyridine and 5 ml of acetic anhydride were added to this, heated at 60°C for 1 hour, and pyridine and acetic anhydride were distilled off under reduced pressure.
Dissolve the residue in chloroform (300ml) and
% aqueous hydrochloric acid solution, followed by washing with a 5% aqueous sodium bicarbonate solution, and the chloroform layer was dried over MgSO ₄ and evaporated under reduced pressure to obtain 1-acetyl-20-O.
-Acetyl-1,2,6,7-tetrahydrocamptothecin is obtained. Dissolve this in 50ml of concentrated sulfuric acid, add fuming nitric acid (0.9ml) to the solution under ice cooling.
was added and stirred for 30 minutes, then poured into ice water (approx.
300ml) and extracted with chloroform (200ml x 3).
times). The chloroform extract was dissolved in MgSO ₄
After drying _with
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=
7Hz, -CH ₂ CH ₃ ), 1.63 (2H, q, J = 7
Hz, -CH ₂ CH ₃ ), 2.23 (3H, s, N-1-
COCH ₃ ), 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=9Hz, 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 MS m/e439 [M ⁺ ] C ₂₂ H ₂₁ N ₃ O ₇ = 439.

Example 2 Production of 10-nitro-1,2,6,7-tetrahydrocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (500mg, 1.14m
mol) in a 20% aqueous sulfuric acid solution (30 ml) and boiled under reflux for 2 hours. Transfer this reaction mixture to ice water (200ml)
and extract with chloroform (200ml x 3). The chloroform layer is dried over magnesium sulfate, filtered, and dried under reduced pressure to obtain 373 mg (82.3% yield) of the title compound as yellow crystals.

mp (decomposition) 274-275℃ (from CHCl ₃ ) IR ^KBr _nax νcm ^-1 : 3480, 1785, 1655, 1610, 1585,
1510, 1315, 1290, 1260 MS m/e397 [M ⁺ ] C ₂₀ H ₁₉ N ₃ O ₆ = 397.

Novel 10-nitro-obtained by the method of the present invention
1,2,6,7-tetrahydro-camptothecin derivatives are important compounds as intermediates for producing various 10-position substituted camptothecin derivatives, as is clear from the description of the reference examples listed below.

Reference example 1 Production of 10-nitrocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (373mg, 0.937m
mol) in dioxane (30ml) and DDQ
(446 mg, 1.968 mmol) was added and boiled under reflux for 1 hour. The reaction mixture was dried under reduced pressure, the residue was dissolved in chloroform (300 ml), and it was dissolved in water (200 ml x
2), and the chloroform layer is dried over magnesium sulfate, filtered, and dried under reduced pressure to obtain 340 mg (92.3% yield) of the title compound as yellow crystals.

mp (decomposition) 243-245℃ [from CHCl ₃ ] NMR (in DMSO-d ₆ ) δ: 0.89 (3H, t, J = 7
Hz, -CH ₂ CH ₃ ), 1.87 (2H, q, J = 7Hz, -
CH ₂ CH ₃ ), 5.28 (2H, s, C-5-H), 5.42
(2H, s, C-17-H), 6.51 (1H, s, C-
20-OH), 7.33 (1H, s, C-14-H), 7.83
(1H, dd, J=9Hz, 2Hz, C-11-H),
8.16 (1H, d, J=9Hz, C-12-H), 8.25
(1H, d, J=2Hz, C-9-H), 8.64 (1H,
s, C-7-H) IR ^KBr _nax νcm ^-1 : 3430, 1742, 1656, 1618, 1592,
1530, 1342, 1158 MS m/e393 [M ⁺ ] C ₂₀ H ₁₅ N ₃ O ₆ = 393.

Reference Example 2 Production of 10-aminocamptothecin 10-nitrocamptothecin (108mg, 0.275m
mol) in ethanol (30ml) - dioxane (20ml)
Platinum oxide (20 mg) was added, and catalytic reduction was carried out at room temperature for 30 minutes at normal pressure. The catalyst is removed and the reaction mixture is dried under reduced pressure to obtain 96 mg (96.2% yield) of 10-aminocamptothecin as a tan solid.

NMR (in DMSO- _d6 ) δ: 0.88 (3H, t, J=7
Hz, -CH ₂ CH ₃ ), 1.86 (2H, q, J = 7Hz, -
CH ₂ CH ₃ ), 5.17 (2H, s, C-5-H), 5.39
(2H, s, C-17-H), 6.90 (1H, d, J=
2Hz, C-9-H), 7.19 (1H, s, C-14-
H), 7.26 (1H, dd, J=9Hz, 2Hz, C-11
-H), 7.84 (1H, d, J=9Hz, C-12-
H), 8.20 (1H, s, C-7-H) _{MS m} /e363 _[ M ⁺ ] _C20H17N3O4 =363.

Reference Example 3 Production of 10-hydroxycamptothecin 10-aminocamptothecin (50mg, 0.138m
mol) in 10% aqueous sulfuric acid solution (5 ml), and dissolved sodium nitrite (9.5 mg, 0.138 mmol) in an ice-salt bath.
Gradually add the aqueous solution. After the dropwise addition is complete, continue stirring for 10 minutes while cooling in an ice-salt bath. Concentrated sulfuric acid (1 ml) was added to the reaction mixture, and the mixture was boiled and refluxed for 2 hours. Dilute the reaction mixture with ice water (200 ml), add chloroform (200 ml), and shake using a separating funnel. The resulting emulsified solution is taken up on Celite. Camptothecin produced by a side reaction is extracted from the chloroform layer, which is dried over magnesium sulfate, filtered, and dried under reduced pressure to recover camptothecin (8 mg).
Meanwhile, the chloroform-water insoluble matter on Celite was
% MeOH-CHCl ₃ (200 ml) and dried under reduced pressure to give the title compound as pale yellow crystals, 28 mg.
(66.5% yield) is obtained.

mp (decomposition) 270-272℃ [from Pyridine-MeOH] NMR (in DMSO- _d6 ) δ: 0.88 (3H, t, J = 7
Hz, -CH ₂ CH ₃ ), 1.86 (2H, q, J = 7Hz, -
CH ₂ CH ₃ ), 5.22 (2H, s, C-5-H), 5.40
(2H, s, C-17-H), 6.47 (1H, s, C-
20-OH), 7.2(2H, m, C-9-H and C
-14-H), 7.41 (1H, dd, J=9Hz, 2Hz,
C-11-H), 8.01 (1H, d, J=9Hz, C-
12-H), 8.43 (1H, s, C-7-H) IR ^KBr _nax νcm ^-1 : 3450, 1720, 1655, 1590, 1505,
1265 Reference Example 4 Production of 10-chlorocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (439mg, 1.00m
mol) in ethanol (30ml) - dioxane (20ml)
Add platinum oxide (60mg) and stir at room temperature for 30 minutes.
Reduce at normal pressure for minutes. The catalyst was removed and the reaction mixture was dried under reduced pressure to give 1-acetyl-10-amino-1,2,6,7-tetrahydrocamptothecin (MS: m/e409 [M ⁺ ] C ₂₂ H ₂₃ N ₃ O ₅ = 409) is obtained. This was dissolved in 12% hydrochloric acid (8 ml), and an aqueous solution of sodium nitrite (104 mg, 1.50 mmol) was gradually added dropwise to the solution in an ice-salt bath. After the addition is complete, the mixture is further stirred for 15 minutes while cooling in an ice-salt bath. The reaction mixture is 60
Cuprous chloride (521 mg, 5.00 m
mol) of 17% hydrochloric acid (10 ml). After the addition is complete, stirring is continued at 60 to 70°C for an additional hour. Transfer the reaction mixture to ice water (300ml)
Dilute with water and extract with chloroform (200ml x 2). The chloroform layer was dried over magnesium sulfate, filtered, and dried under reduced pressure to give 1-acetyl-
10-chloro-1,2,6,7-tetrahydrocamptothecin (MS: m/e428 [M ⁺ ], 430 [M+2]
_{C22H21N2O5Cl = 428.5} ) is obtained _. Dissolve this in 30% sulfuric acid aqueous solution (20 ml) and leave for 1.5 hours.
Boil to reflux, dilute the reaction mixture with ice water (200 ml), and extract with chloroform (150 ml x 3). The chloroform layer was dried over magnesium sulfate, filtered, and dried under reduced pressure.
1,2,6,7-tetrahydrocamptothecin is obtained. Dissolve this in dioxane (30ml),
Add DDQ (288 mg, 0.634 mmol) to the solution,
Boil and reflux for 1.5 hours. The reaction mixture was dried under reduced pressure, the residue was dissolved in chloroform (300 ml), washed with water (100 ml x 2), the chloroform layer was dried over magnesium sulfate, filtered and dried under reduced pressure to give the title compound as white crystals,
184 mg (48.0% yield, from 1-acetyl-10-nitro-1,2,6,7-tetrahydrocamptothecin) is obtained.

mp (decomposition) 279-280℃ [from CHCl ₃ ] NMR (in DMSO-d ₆ ) δ: 0.89 (3H, t, J = 7
Hz, -CH ₂ CH ₃ ), 1.87 (2H, q, J = 7Hz, -
CH ₂ CH ₃ ), 5.28 (2H, s, C-5-H), 5.42
(2H, s, C-17-H), 6.51 (1H, s, C-
20-OH), 7.33 (1H, s, C-14-H), 7.83
(1H, dd, J=9Hz, 2Hz, C-11-H),
8.16 (1H, d, J=9Hz, C-12-H), 8.25
(1H, d, J=2Hz, C-9-H), 8.64 (1H,
s, C-7-H) IR ^KBr _nax νcm ^-1 : 3400, 1745, 1650, 1585, 1490,
1225, 1155 MS: m/e382 [M ⁺ ], 384 [M + 2]
As _{C20H15N2O4Cl = 382 .}

Reference example 5 Production of 10-bromocamptothecin 1-acetyl-10-nitro-1,2,6,7-
Tetrahydrocamptothecin (439mg, 1.00m
mol) in ethanol (30ml) - dioxane (20ml)
Add platinum oxide (60mg) and bring to room temperature.
Contact reduce for 30 minutes. The catalyst was removed and the reaction mixture was dried under reduced pressure to give 1-acetyl-10-amino-1,2,6,7-tetrahydrocamptothecin (MS: m/e409 [M ⁺ ]C ₂₂ H ₂₃ N ₃ O ₅ =409)
is obtained. This was dissolved in 24% hydrogen bromide water (10 ml), and an aqueous solution of sodium nitrite (104 mg, 1.50 mmol) was gradually added dropwise to the solution in an ice-salt bath. After the addition is complete, cool in an ice-salt bath,
Continue stirring for 15 minutes. 24% of cuprous bromide (717 mg, 5.00 mmol) the reaction mixture was warmed to 60-70 °C.
Add dropwise to hydrogen bromide solution (10 ml). After the addition is complete, stirring is continued for an additional hour at 60-70°C. The reaction mixture was diluted with ice water (200 ml) and extracted with chloroform (200 ml x 3). The chloroform layer was dried over magnesium sulfate, filtered, and dried under reduced pressure to give 1-acetyl-10-bromo-1.2.
6,7-tetrahydrocamptothecin (MS:
m/e472[M ⁺ ], 474[M+2]C ₂₂ H ₂₁ N ₂ O ₅ Br=
473) is obtained. Dissolve this in a 30% aqueous sulfuric acid solution (20 ml) and boil under reflux for 1 hour. The reaction solution was diluted with ice water (200 ml) and chloroform (200 ml) was added.
×3) Extract. The chloroform layer was dried over magnesium sulfate, filtered, dried, sprinkled on Celite, and subjected to silica gel column chromatography (1
%MeOH- _CHCl3 ), 10-bromo-
1,2,6,7-tetrahydrocamptothecin (MS: m/e430 [M ⁺ ], 432 [M+2]
C ₂₀ H ₁₉ N ₂ O ₄ Br=431) is obtained. Dissolve this in dioxane (20ml) and add it to the solution.
Add DDQ (264 mg, 0.58 mmol) and boil under reflux for 40 minutes. The reaction mixture was dried under reduced pressure, the residue was dissolved in chloroform (300 ml) and water (200 ml
2), and the chloroform layer was dried over magnesium sulfate, filtered, dried under reduced pressure, sprinkled on Celite, and subjected to silica gel column chromatography (1).
% pyridine- _CHCl3 ) to give the title compound as white crystals, 155 mg (36.3% yield,
1-acetyl-10-nitro-1,2,6,7-tetrahydrocamptothecin) is obtained.

mp (decomposition) 273-275℃ [from CHCl ₃ ] NMR (in DMSO-d ₆ ) δ: 0.89 (3H, t, J = 7
Hz, -CH ₂ CH ₃ ), 1.87 (2H, q, J = 7Hz, -
CH ₂ CH ₃ ), 5.28 (2H, s, C-5-H), 5.41
(2H, s, C-17-H), 6.48 (1H, s, C-
20-OH), 7.34 (1H, s, C-14-H), 7.93
(1H, dd, J=9Hz, 2Hz, C-11-H),
8.09 (1H, d, J=9Hz, C-12-H), 8.41
(1H, d, J=2Hz, C-9-H), 8.63 (1H,
s, C-7-H) IR ^KBr _nax νcm ^-1 : 3400, 1750, 1655, 1590, 1225,
1160 MS m/e426 [M ⁺ ], 428 [M+2]
As _{C20H15N2O4Br = 426 .}

Claims (1)

[Claims] 1. Camptothecin is catalytically reduced, and 1.
A general formula characterized by treating 2,6,7-tetrahydrocamptothecin with an acylating agent and treating the obtained acylated product with sulfuric acid and nitric acid to introduce a nitro group at the 10-position, (In the formula, R is an acyl group.) 10
-Production method of nitro-1,2,6,7-tetrahydrocamptothecin derivative. 2 Camptothecin was catalytically reduced, resulting in 1.
10-Nitrocamptothecin was obtained by treating 2,6,7-tetrahydrocamptothecin with an acylating agent, and treating the resulting acylated product with sulfuric acid and nitric acid to introduce a nitro group at the 10-position. A general formula characterized in that the acyl group present in the derivative is removed by hydrolysis, (In the formula, R is a hydrogen atom.) 10
-Production method of nitro-1,2,6,7-tetrahydrocamptothecin derivative.