JPS6152152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing pyrazofurin (general formula, 1' position means β form). However, its intention is to have anti-tumor properties (MJSweeney
et al., Cancer Res., 33, 2619 (1973)) or antibacterial action (GEGutowski et al., Ann.NYAcad.
Sci., 255, 544 (1975).

Pyrazofrine (pyrazomycin)
It is a C-nucleoside isolated from the culture solution of Strcptmyces candidus strain (GDDaves Jr. et al.
Prog.Med.Chem.13, 303 (1976); K.Gerzon
et al., 2nd International Conference on Heterocycles, Proceedings, p131
(1969)), and its pharmacological effects have recently attracted attention. On the other hand, regarding its production method, only three synthetic methods other than the culture method have been reported. (J.Farkas, Tetrahedron Letters,
1972, 2279; S. De Bernardo et al., J.Org.Chem.
41, 287 (1976); JGBuchanan et al., J.Chem.
Soc. Perkin I, 1981, 2374) Each of these production methods has room for improvement in terms of yield, raw material selection, reaction steps, etc. For example, the Fuukas method uses C-glycosides of phloroglucin derivatives, the Bernardo method uses C-glycosides from acetone dicarboxylic acid esters, and the Buquianin method uses 3-glycosides.
-This method uses the C-nucleoside of cyano-4-nitro-pyrazole as the starting material, but the Fuakas method has problems in terms of yield (total yield 4.5%), and the latter two methods have difficulties in producing the starting material. There is.

In contrast, the present invention provides C-
Glycoside, i.e. 4-C-(2'·3'-O-isopropylidene-5'-O-trityl (or aroyl-D-ribofuranosyl)-acetoacetate (general formula I, in which R ₁ is a lower alkyl group) , R ₂ is a trityl or aroyl group, X is H ₂ ) is diazotized with tosyl azide, and the 2-diazo form (general formula, in which R ₁ is a lower alkyl group, R ₂ is a trityl or aroyl group) is diazotized with tosyl azide. The base, X is
This product is stirred with a metal hydride, such as sodium hydride, at room temperature for several hours in an inert organic solvent, such as in a nitrogen stream, in an inert organic solvent, such as Digray _, for ring closure, and the pyrazole form ( An amide form (general formula, in which R ₂ is a trityl or aroyl group, and _Y is an O-alkyl group) is produced by ammonolysis.
In this method, after producing pyrazofurin (Y means an amino group), a deprotection reaction is performed to produce pyrazofurin (general formula). For ammonolysis, heating with aqueous ammonia or ammonia-alcohol in a sealed tube at about 90° is sufficient for several hours, and for deprotection reaction, it is only necessary to leave the mixture with trifluoroacetic acid for about 1 hour. Furthermore, α-form and β-form can be easily separated by silica gel column chromatography. The solvent system can be chosen appropriately, but a mixture of n-hexane and ethyl acetate is advantageous, for example. The yield is approximately
It is 45%. In terms of yield, this method is superior to the Fuerkas method (4.5%), as well as the Bernardo method (approximately 34%).
%), which is comparable to the Bukiyanin method (42%), but it is particularly characterized by the fact that the raw materials can be produced much more easily than other methods.

That is, C-glycoside of acetoacetate (the above compound, in the formula R ₁
is a lower alkyl group, R ₂ is a trityl or aroyl group _, and It is characterized by the fact that it is manufactured. That is, 3-alkoxycarbonyl-2-oxopropylidene triphenylphosphorane (Ph ₃ PCH・CO・CH ₂・CO ₂ R ₁ , in which R ₁ means a lower alkyl group) obtained from diketene in two steps. Protected D-ribofuranose, 2,3-O-isopropylidene-5-O
-trityl-D-ribofuranose in an inert organic solvent under heating under reflux. As a solvent, benzene or toluene can be used, but especially acetonitrile can be used for long periods of time (50-
It is almost quantitative when heated under reflux (90 hours).

Therefore, the present invention provides 3-alkoxycarbonyl-
2-oxopropylidenetriphenylphosphorane (Ph ₃ PCH・CO・CH ₂・CO ₂ R, in the formula, R means a lower alkyl group) and a calculated amount of 2.3-O-isopropylidene-5-O -Trityl-D-ribofuranose is produced, followed by diazotization (), ring closure (), ammonolysis (), and deprotection reaction to produce pyrazofurin (). In addition, the epimer α-form and β-form at the 1′ position of the sugar moiety can be easily separated from each other, including pyrazofurin (), by silica gel column chromatography. Further, the C-glycoside of acetoacetate (2), which is a starting material, is a mixture of α and β-epimers at the 1' position and does not necessarily crystallize, but may be used in the next reaction as is.

The method of the present invention will be explained below by way of examples.

Example 1 4-C-(2'・3'-O-isopropylidene-5'-
O-trityl-D-ribofuranosyl)-ethyl acetoacetate (general formula, in which R ₁ is an ethyl group,
_2,3 -O-isopropylidene-5-O-trityl-D-ribofuranose (10.9 g, 25 mmol) and 3-ethoxycarbonyl _- 2- Oxopropylidenetriphenylphosphorane (Ph ₃ P・CH・
CO.CH ₂ .CO ₂ Et) (11.8 g, 30 mmol) is dissolved in acetonitrile (30 ml) and heated under reflux for 72 hours. The solvent was distilled off under reduced pressure, and the residue was subjected to silica gel (300 g) column chromatography. n-
Elution with hexane-ethyl acetate (9:1) yields 13.5 g (quantitative) of a colorless viscous liquid.

Analytical value: As C ₃₃ H ₃₆ O ₇ Calculated value: C, 72.77; H, 6.66 Actual value: C, 72.86; H, 6.71 Infrared absorption spectrum (chloroform): 1740,
1720cm ^-1 Example 2 4-C-(2'・3'-O-isopropylidene-5'-
Ethyl O-trityl-D-ribofuranosyl)-2-diazo-acetoacetate (general formula, in which R _1
means ethyl group, R ₂ is trityl group, ) and leave at room temperature for 30 minutes. The reaction solution was concentrated under reduced pressure, benzene was added to the resulting residue, and insoluble materials were filtered off. The benzene filtrate was concentrated under reduced pressure, and the residue was subjected to silica gel (400 g) column chromatography. Concentrate the eluate with n-hexane-ethyl acetate (9:1) to obtain 12.2 g (94%) of a colorless viscous liquid.
get.

Analytical value: C ₃₃ H ₃₄ N ₂ O ₇・1/5C ₆ H ₁₄ Calculated value: C, 69.87; H, 6.31; N, 4.77 Actual value: C, 70.04; H, 6.13; N, 4.99 Infrared absorption Spectrum (chloroform): 2150,
1710, 1645cm ^-1 Example 3 3-(2'・3'-O-isopropylidene-5'-O-
Method for producing trityl-D-ribofuranosyl)-4-hydroxypyrazole-5-carboxylic acid ethyl ester (general formula, in which R ₂ means a trityl group and Y means an ethoxyl group) Sodium hydride (50% oily liquid, 2.6 g, 55 mmol) was suspended in anhydrous diglyme (60 ml) and stirred under ice cooling in a nitrogen stream. Add the above compound (6.5 g, 11 mmol) to this solution and anhydrous diglyme (60
ml) solution dropwise. After dropping half the amount (30ml), return the temperature to room temperature and continue dropping. After stirring for 3 hours, the mixture was cooled on ice again and a solution of acetic acid (3.3 g, 55 mmol) in anhydrous diglyme (10 ml) was added dropwise. The reaction solution was concentrated under reduced pressure, a small amount of water was added to the residue, and the mixture was extracted with ether. The ether layer is washed with water, dried, and then concentrated. The residue was subjected to silica gel chromatography, and 5.2 g (82%) of a colorless viscous liquid was obtained from the eluate with n-hexane-ethyl acetate (3:1).

Analytical value: C ₃₃ H ₃₄ N ₂ O ₇・3/4CH ₃・CO ₂ C ₂ H ₅ Calculated value: C, 67.91; H, 6.33; N, 4.40 Actual value: C, 67.72; H, 6.06; N , 4.60 Infrared absorption spectrum (chloroform): 3440,
1720, 1685cm ^-1 Furthermore, add this to silica gel (800
g) By subjecting to column chromatography, 3.5 g of the β form of mp159-160° (colorless prism, recrystallized from ether) was obtained from the first distillate in the same solvent.
(55%).

Analytical value: C ₃₃ H ₃₄ N ₂ O ₇ Calculated value: C, 69.46; H, 6.01; N, 4.91 Actual value: C, 69.29; H, 6.05; N, 4.64 Infrared absorption spectrum (chloroform): 3440,
1720, 1685 cm ^-1 Continuing elution, a colorless viscous liquid α is obtained from the after distillate.
body, 1.5g (24%).

Example 4 3-(2'・3'-O-isopropylidene-5'-O-
Process for producing (trityl-D-ribofuranosyl)-4-hydroxypyrazole-5-carboxamide (general formula, in which R ₂ means a trityl group and Y means an amino group) (a) The above ethyl ribofuranosyl-pyrazole-carboxylate Ester (general formula, in which _R2 means trityl group, Y means ethoxyl group) (1.2
g, 1.9 mmol) at 0° in anhydrous methanol saturated with ammonia (35 ml) and heated in a sealed tube at 90-95° for 2 hours. After opening the tube, the reaction solution was concentrated and the residue was subjected to silica gel (60 g) column chromatography. Elute with n-hexane-ethyl acetate (3:1) to obtain the β form (colorless viscous liquid) from the first distillation.

Analytical value: C ₃₁ H ₃₁ N ₃ O ₆・1/2CH ₃・CO ₂ C ₂ H ₅ Calculated value: C, 67.68; H, 6.02; N, 7.17 Actual value: C, 67.59; H, 5.92; N , 7.29 Infrared absorption spectrum (chloroform): 1665cm
^-1 Continuing the elution, the -α form, which is also a colorless viscous liquid, is obtained from the after-distillate.

Analytical value: C ₃₁ H ₃₁ N ₃ O ₆・3/4CH ₃・CO ₂ C ₂ H ₅ Calculated value: C, 67.20; H, 6.14; N, 6.91 Actual value: C, 66.96; H, 6.21; N , 7.09 Infrared absorption spectrum (chloroform): 1665cm
^-1 (b) The β-epimer compound (2.3 g, 4 mmol) prepared in Example 3 was dissolved in ammonia-anhydrous methanol (70 ml) saturated at 0°, and heated at 90-95° C. for 5 hours in a sealed tube. Heat to °. After opening the tube, it was treated in the same manner as before, and a colorless viscous liquid -β was obtained by silica gel (60 g) column chromatography.
body, 2.2g (94%). Identified as standard by infrared absorption spectrum.

Example 5 Process for producing pyrazofurin (general formula) The β form of the compound produced in Example 4(a) (1.76 g, 3 mmol) was dissolved in 90% trifluoroacetic acid (40 ml), left at room temperature for 45 minutes, and then placed on ice. Concentrate under reduced pressure under cooling (below 5°). The residue was subjected to silica gel (360 g) column chromatography, and ethyl acetate-acetone-methanol-water (6:1:
1:1) to obtain 0.71 g (85%) of colorless prisms (recrystallized from water) with mp 108-110°.

Analytical value _{: C9H13N3O6 ・ H2O} Calculated value: C _, 38.99; H, 5.45; N, 15.16 Actual value: C, 38.96; H, 5.34; N, 15.20 Further elute with the same solvent. Continuing, colorless needle crystals of mp69-70° (recrystallized from water), pyrazofurin B (V
0.06 g (7%) of -α-epimer form) was obtained.

Analytical value _{: C9H13N3O6 ・ 2H2O} Calculated value: C, 36.61; H, 5.80; N, 14.23 Actual value _: C, 36.31; H, 5.89; N, 14.36 More than virazofrine (V- The infrared absorption spectra of pyrazofurin B (β form) and pyrazofurin B (V-α form) completely matched the spectra of commercially available products.

Claims (1)

[Claims] 1 4-C-(2'・3'-O-isopropylidene-
5′-O-substituted-D-ribofuranosyl)-acetoacetate (the following general formula, in which R ₁ is a lower alkyl group, R ₂ is a trityl or aroyl group, and X is H ₂
) is diazotized with tosyl azide in the presence of triethylamine to produce a 2-diazo compound (the following general formula, in which R ₁ is a lower alkyl group, R ₂ is a trityl or aroyl group, and X is N ₂ ) death,
This product was ring-closed by stirring at room temperature in a nitrogen stream in the presence of a metal hydride such as _sodium hydride in an inert organic solvent at room temperature. means an O-alkyl group),
This product is ammonolyzed in a conventional manner to produce an amide compound (the following general formula, in which R ₂ is a trityl or aroyl group, and Y is an amino group), and this product is deprotected with trifluoroacetic acid to produce pyrazofurin. (In the following general formula, the 1' position means the β position). 2 3-Alkoxycarbonyl-2-oxopropylidenetriphenylphosphorane (general formula
Ph ₃ PCH・CO・CH ₂・CO ₂ R ₁ (in the formula, R ₁ means a lower alkyl group), D-ribose with 2, 3 and 5 positions protected, 2, 3-O-isopropylidene- 5-O-trityl (or aroyl)-D-
ribofuranose and heated under reflux in an inert organic solvent to produce ribofuranosyl acetoacetate (the following general formula, in which R ₁ is a lower alkyl group, R ₂ is a trityl or aroyl group, and X means H ₂ ). This product was diazotized with tosyl azide in the presence of triethylamine, and then ring-closed in an inert solvent at room temperature in the presence of sodium hydride in a nitrogen stream to obtain a ribofuranosyl pyrazole compound (the following general formula, in which R ₂ is trityl). or an aroyl group, Y means an O-alkyl group), which is further ammonolyzed and deprotected to produce pyrazofurin (in the following general formula, the 1' position means the β-form).