JPH083168A - 4-methyl-9h-imidazo(1,2-a)purin-9-ones - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a DNA intercalater, applicable for synthesis of tricyclic nucleic acid bases in a wide range, having strong fluorescence simply and in high yield by reacting a prescribed compound with an amino-alchol and subjecting to condensation reaction. CONSTITUTION:This compound of formula I [R<1> is H, a lower alkyl or a (substituted)phenyl] is reacted with an amino-alcohol of formula II (R<2> and R<3> are each H or a lower alkyl) and subjected to ring condensation to give the objective 4-methyl-1,4,6,7-tetrahydro-9H-imidazo[1,2-a]purin-9-one of formula II. For example, 2-aminoethanol is used as the alcohol, 4-7mols of 2-aminoethanol is used based on 1mol of the raw material compound and the reaction is carried out at 80-140 deg.C for 1-15 hours. In the condensation ring closure reaction, 5-8mols of a condensation ring closure agent such as polyphosphoric acid is used and the reaction is effected at 120-160 deg.C for 12-36 hours.

Description

Detailed Description of the Invention

[0001]

The present invention relates to 4-methyl -9 H - imidazo [1,2-a] novel obtained by purin-9-ones preparation and method 4-methyl -9 H -Imidazo [1,2- a ] purin-9-ones.

[0002]

2. Description of the Related Art It is known that transfer ribonucleic acid (tRNA) has modified bases in addition to ordinary nucleic acid bases. For example, fluorescent condensed tricyclic bases (Y-bases) having a 1 H -imidazo [1,2- a ] purine skeleton are present at a position adjacent to the 3 ′ end of the anticodon of eukaryotic phenylalanine tRNA. It has been reported. Conventionally, Y-
At present, most attempts have not been made to synthesize the derivatives and analogs around this, probably because no effective activity has been found for the bases.

On the other hand, regarding the base moiety of Y-bases, that is, the tricyclic nucleic acid bases, the method of Goto et al. And the method of Nakanishi et al. Have been reported. The method of Goto et al. Is a method of reacting 2-amino-3-methyl-6-oxo-3,6-dihydropurine with bromoketones and then performing condensation ring closure (Tetrahed).
ron lett., 2725 (1971), Biochemistry, 15,898 (1976))
And the method of Nakanishi et al., In the presence of sodium hydride,
A method of reacting 2-amino-3-methyl-6-oxo-3,6-dihydropurine with benzyl bromide to protect the 7-position, then reacting with a bromoketone, and then removing the protecting group (J. Org. Chem., 43, 1644 (1978)).

[0004]

However, these methods have problems such as low yield and narrow applicable range, and are not always satisfactory methods for synthesizing tricyclic nucleobases. . Therefore, an object of the present invention is to find a method for synthesizing tricyclic nucleobases having a wide range of application and to provide a useful compound obtained by the method.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have established a simple novel method for synthesizing tricyclic nucleobases, and obtained by this method. Found that the compound obtained has a strong fluorescence,
The present invention has been completed. That is, the present invention relates to a compound represented by the following formula (1) and an amino alcohol [H ₂ NC
H (R ₂ ) CH (R ₃ ) OH] and then condensation-ring closure to obtain a compound represented by the following formula (3): 4-methyl-1,4,6,6 7-tetrahydro-9
The present invention relates to a method for producing H -imidazo [1,2- a ] purin-9-ones.

[0006]

[Chemical 7]

Embedded image

(In the formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group, R ² and R ³ may be the same or different, and are hydrogen or a lower alkyl group. The present invention also provides 4-methyl-represented by the above formula (3).
1,4,6,7- tetrahydro -9 H - imidazo [1,
2- <a> ] purin-9-ones. Furthermore, the present invention is characterized by obtaining the above formula (3) oxidizing the compound represented by the with a compound represented by the following formula (4), 4-methyl-1,4-dihydro -9 H -The present invention relates to a method for producing imidazo [1,2- a ] purin-9-ones.

[0008]

[Chemical 9]

(In the formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group, and R ² and R ³ may be the same or different, and are hydrogen or a lower alkyl group. Furthermore, the present invention also provides 4- represented by the following formula (4 ′).
Methyl-1,4-dihydro -9 H - imidazo [1,2-
a ] [Purin-9-ones]

[0010]

[Chemical 10]

(In the formula, R ^{1 ′} represents a lower alkyl group or a substituted or unsubstituted phenyl group, and R ^{2 ′} and R ^{3 ′} represent hydrogen.) The present invention will be described in detail below.

Manufacturing method of the present invention: The manufacturing method of the present invention is shown below by a flow chart.

[0013]

[Chemical 11]

In the above formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group, and R ² and R ³ may be the same or different and each represent hydrogen or a lower alkyl group. Show. Here, the lower alkyl group means an alkyl group having about 1 to 5 carbon atoms such as methyl and ethyl, and the substituted phenyl group means an alkyl-substituted phenyl group represented by 4-methylphenyl, 4-methoxyphenyl. Represented by alkoxy-substituted phenyl group, halogen-substituted phenyl group such as 2-chlorophenyl, 4-bromophenyl, 4-fluorophenyl, 4-hydroxyphenyl group, 4- (3,4-methylenedioxy) phenyl group, etc. To do.

The starting compound represented by the formula (1), 3-methyl-2-methylthio-6-oxo-3,6-dihydro-
7 H -purines can be prepared by known methods (Heterocycles, 33, 775 (19
92)). Specific examples of such compounds include 3-methyl-2-methylthio-
6-oxo-3,6-dihydro -7 H - purine, 3,8
- dimethyl-2-methylthio-6-oxo-3,6-dihydro -7 H - purine, 3-methyl-2-methylthio -
6-oxo-8-phenyl-3,6-dihydro -7 H -
Pudding etc. are mentioned.

The first step in the method of the present invention is a reaction step in which the above-mentioned raw material compound is reacted with an amino alcohol and then condensed and ring-closed to obtain a compound represented by the formula (3). The amino alcohol used in the reaction includes H ₂ N
CH (R ₂ ) CH (R ₃ ) OH (R ² and R ^{3, which} may be the same or different, each represents hydrogen or a lower alkyl group.) Is 2-aminoethanol, 2-amino-1-propanol, 1-
Amino-2-propanol etc. can be mentioned.
The amount of amino alcohol used is appropriately in the range of 4 to 7 times mol per mol of the raw material compound. The reaction between the raw material compound and the amino alcohol is 1 at a reaction temperature of 80 to 140 ° C.
It can be performed by stirring for 15 hours.

The condensed ring-closing reaction is carried out using a condensed ring-closing agent such as polyphosphoric acid or phosphorus oxychloride. That is,
Using 5 to 8 moles of the condensation ring-closing agent with respect to 1 mole of the compound obtained by reacting the raw material compound with the amino alcohol, 100 to 180 ° C. (preferably 120 to 160)
The reaction can be carried out by stirring at 1 to 48 hours (preferably 12 to 36 hours).

The next step of the method of the present invention is a reaction step of reacting the compound of formula (3) with an oxidizing agent to obtain the compound of formula (4). As the oxidizer, manganese dioxide, chloranil, etc. can be used. The amount of the oxidizing agent used is not particularly limited, and an appropriate amount to an excessive amount of the oxidizing agent may be used.
The reaction of the compound of the formula (3) with the oxidizing agent is carried out in an aprotic organic solvent such as N , N -dimethylformamide, dioxane, N , N -dimethylacetamide, acetonitrile or dimethylsulfoxide at 100 to 180 ° C. (preferably, 120 to 160 ° C.) for 1 to 48 hours (preferably,
The reaction can be performed by stirring for 12 to 36 hours.

After completion of the reaction, the compound of the formula (4) can be isolated and purified by appropriately combining the usual methods used for the isolation and purification of heterocycles (for example, various chromatographic methods, recrystallization methods, etc.). it can. When the isolation and purification of the compound is required in the above reaction step, the same method can be used.

Compound of the present invention: The compound of the present invention is represented by the above formula (3), (4) or (4 '), wherein R ¹ , R ^1' , R ² and R ^{2 ′} , R ³ and R ^{3 ′} are as defined above. Among such compounds, the compounds represented by the formula (3) and the formula (4 ′) are novel compounds that have never been reported so far to the inventor's knowledge. Specific examples of such compounds of the present invention include those shown in Tables 1 and 2 below.

[0021]

[Table 1]

[Table 2]

[0022]

INDUSTRIAL APPLICABILITY The production method of the present invention enables the target compound to be synthesized in a high yield by a simple operation method and can be applied to the synthesis of a wide range of tricyclic nucleobases. It is a useful method that can be used.
In addition, as clearly shown in the examples below, the compounds of the present invention have strong fluorescence (especially, fluorescence relative quantum yield of 0.1 or less).
Since it has the above), it can be expected as an intercalator for DNA. It can also be used as a fluorescent probe for investigating the environment surrounding DNA by utilizing the characteristic of fluorescence. Furthermore, the compound represented by the formula (3) is the 4-methyl-1,4 represented by the formula (4).
- dihydro -9 H - imidazo [1,2-a] purin -9
It is also useful as a synthetic intermediate in the synthesis of -ones.

[0023]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto. The compound numbers in the examples correspond to those in Tables 1 and 2 and Tables 3 and 4 below.

[0024]

[Table 3]

[Table 4]

Example 1: Synthesis of compound (2a) and its 8-substituted derivative (2d-r) Starting compound (1a) or its 8-substituted derivative (1b-)
p) (5 mmol) with 2-aminoethanol (1.5
g, 25 mmol) was added, and the mixture was heated with stirring at 110 ° C. for 3 to 10 hours. After completion of the reaction, add ethanol (30 m
l) was added and diluted to precipitate crystals. This was collected by filtration and recrystallized from N , N -dimethylformamide (DMF) to obtain the desired product as colorless powder crystals.

Example 2: Synthesis of compound (2b) DL-2-Amino-1-propanol (1.87 g, 25 mmol) was added to the starting compound (1a) (5 mmol) and the same procedure as in Example 1 was performed. The desired product was obtained as colorless powder crystals.

Example 3: Synthesis of compound (2c) Starting compound (1a) (5 mmol) was added to 1-amino-2-
Add propanol (1.87g, 25mmol) and add 1
The mixture was heated and stirred at 10 ° C for 8 hours. After completion of the reaction, ethanol (30 ml) was added to the reaction solution to dilute it to precipitate crystals. This was collected by filtration and recrystallized with DMF to obtain the target substance as colorless powder crystals.

Example 4: Compounds (3a-c) and Part 2
-Synthesis of alkyl derivative (3d, e) The compound (2a-e) (2mmo obtained in Examples 1 to 3)
l) polyphosphoric acid (PPA) (4.05 g, 12 mmo
1) was added, and the mixture was heated with stirring at 140 ° C. for 24 hours. After the reaction was completed, the reaction mixture was poured into ice water, neutralized with 2N aqueous sodium hydroxide solution, the water was completely distilled off under reduced pressure, and the residue was recrystallized from anhydrous dioxane to give the desired product as colorless powder crystals. Got

Example 5: Synthesis of 2-aryl derivative (3f-r) of compound (3a) Compound (2f-r) (2mmol) obtained in Example 1
PPA (4.05 g, 12 mmol) was added to
The mixture was heated and stirred at ℃ for 24 hours. After completion of the reaction, the reaction mixture was poured into ice water to precipitate a solid. This was collected by filtration, washed with a 5% aqueous solution of sodium carbonate (20 ml) and water (10 ml), dried and recrystallized with DMF to obtain the desired product as colorless powder crystals.

Example 6: Synthesis of compound (4a-r) The compound (3a-r) (2m obtained in Examples 4 and 5)
manganese dioxide (1.74 g, 20 mmol) was added to a DMF (50 ml) solution of 100 mol.
The mixture was heated and stirred for an hour. After the reaction was completed, the precipitate was filtered off, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was purified by column chromatography (Kiesel gel 60, 70-230 mesh, eluent: ethyl acetate). The eluate was concentrated under reduced pressure, and the residue was recrystallized with ethanol to obtain the target substance as colorless powder crystals. The physicochemical properties of the compounds of the present invention obtained by synthesis in the above Examples are shown in Tables 5 to 18 below.

[0031]

[Table 5]

[0032]

[Table 6]

[Table 7]

[Table 8]

[0033]

[Table 9]

[0034]

[Table 10]

[Table 11]

[Table 12]

[0035]

[Table 13]

[0036]

[Table 14]

[0037]

[Table 15]

[Table 16]

[Table 17]

[0038]

[Table 18]

Example 7: Measurement of fluorescence relative quantum yield (Measurement method) As reagents Rhodamine B and quinine, special grade products manufactured by Wako Pure Chemical Industries, Ltd. were used. As 0.1 N sulfuric acid, a volumetric reagent manufactured by Wako Pure Chemical Industries, Ltd. was used, and as the measurement solvent, ethanol was used which was purified by an ordinary purification distillation method. Equipment The absorption spectrum was measured using Hitachi 150-20 type double beam spectrophotometer (150w xenon lamp, 1cm quartz cell) equipped with a constant temperature bath at 25 ° C. Hitachi F with
A -4000 type spectrofluorimeter (150w xenon lamp, 1 cm quartz cell) was used. As the fluorescent standard substance, quinine 0.1N sulfuric acid acidic solution (λem.max: 4
54 nm), and a rhodamine B solution (λem.max: 590 n was used to correct the excitation spectrum by a photon meter.
m) was used.

Measurement of Excitation and Fluorescence Spectra of Samples As samples, 10 ⁻⁵ M or 10 ⁻⁵ M of each compound was used.
^After preparing an ^-6 M ethanol solution X and determining the optimum excitation wavelength with a Hitachi F-4000 type spectrofluorimeter using a 1 cm quartz cell, the fluorescence spectrum was measured at 25 ° C. Next, wave number integration of this fluorescence spectrum was performed to obtain an integrated value Fx. 10 ^{over 6} M 0.1 N sulfuric acid solution S of quinine were prepared as a measurement standard of the fluorescence spectrum of quinine, the fluorescence spectrum was measured quinine at the optimal excitation wavelength was determined in each sample. Next, wave number integration was performed to obtain an integrated value Fs.

Measurement of UV absorption spectrum of sample and quinine Ultraviolet absorption spectrum of 10 ^-4 M or 10 ^-5 M ethanol solution of each compound and quinine 10 ^-4 M 0.1N sulfuric acid solution was measured by Hitachi 150-20 type double. This was done using a beam spectrophotometer. The absorbance at the excitation wavelength of the sample and the standard sample solution (quinine) was measured with Ax and A, respectively.
Let s. Calculating method of fluorescence relative quantum yield Fluorescence relative quantum yield Qx with respect to quinine S of sample X
Was calculated from the following formula.

[0042]

[Equation 1]

(Results) The measurement results are shown in Tables 19 and 20 below.
Shown in

[0044]

[Table 19]

[0045]

[Table 20]

Claims (4)

[Claims] 1. Formula (1): (In the formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group.) And an amino alcohol [H ₂ NCH (R ₂ ) CH (R ₃ ) OH:
R ² and R ³ may be the same or different,
It represents hydrogen or a lower alkyl group. ] After reacting,
And condensation ring-closing, characterized in that to obtain a compound represented by the following formula (3), 4-methyl, 4,6,7-tetrahydro -9 H - imidazo [1,2-a] purin -9 -A method for producing ons. Embedded image (In the formula, R ¹ , R ² and R ³ are as defined above.) 2. Formula (3): (In the formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group, and R ² and R ³ may be the same or different and represent hydrogen or a lower alkyl group.) 4-methyl-1,4,6,7- represented by
Tetrahydro -9 H - imidazo [1,2-a] purin -
9-ones. 3. Formula (3): (In the formula, R ¹ represents hydrogen, a lower alkyl group or a substituted or unsubstituted phenyl group, and R ² and R ³ may be the same or different and represent hydrogen or a lower alkyl group.) The compound represented by the following formula (4)
Characterized in that to obtain a compound represented by in, 4-methyl-1,4-dihydro -9 H - imidazo [1,2-a] preparation of purin-9-ones. Embedded image (In the formula, R ¹ , R ² and R ³ are as defined above.) 4. Formula (4 ′): (In the formula, R ^{1 ′} represents a lower alkyl group or a substituted or unsubstituted phenyl group, and R ^{2 ′} and R ^{3 ′} represent hydrogen.) 4-methyl-1,4-dihydro-9 H
-Imidazo [1,2- a ] purin-9-ones.