DE4112630A1 - Protected D-mannose derivs. - for prodn. of 2-keto-3-deoxy-D-manno-octonic acid bacterial lipo-polysaccharide components - Google Patents

Abstract

D-Mannose derivs. of formula (I) are new; where X = O or a gp. of formula X1; where R5 = CH2Ar or 1-6C alkyl; R1-R4 = 1-3C alkyl, or R1+R2 and/or R3+R4 may form a 5- or 6-membered ring; Ar = phenyl substd. by 0-2 of 1-4C alkyl or alkoxy. Intermediates of formula (III) are also new. Prodn. of 2-keto-3 -deoxy-D-manno -octonic acid derivs. of formula (II) is effected by catalytic hydrogenolysis of cpds. (I; X=X1); where R6 = H or 1-6C alkyl. USE - Cpds. (II) are useful as intermediates for synthesis of bacterial lipopolysaccharides with immunostimulant and antitumour activity.

Description

The present invention relates to new derivatives of D-mannose general formula I.

in which the substituents have the following meaning:
X is oxygen or a radical of the general formula II

where R⁵ represents a radical -CH₂Ar or a C₁-C₆ alkyl group,
R¹-R⁴ C₂-C₃-alkyl groups, where the radicals R¹ and R² or R³ and R⁴ can each be linked to form a 5- or 6-membered ring,
Ar is a phenyl group which can carry one or two C₁-C₄-alkyl and or C₁-C₄-alkoxy groups as substituents.

The invention further relates to rosin salts of the general Formula III

in which Z means halogen.  

The invention also relates to processes for the production of these Compounds and processes for the preparation of derivatives of 2-keto-3- deoxy-D-manno-octonic acid of the general formula V

in which R⁶ represents hydrogen or C₁-C₆ alkyl.

3-keto-2-deoxy-D-manno-octonic acid (also called KDO for short; VI)

is an important component of lipopolysaccharides (LPS). These form the outer cell membrane of with other macromolecules Gram-negative bacteria.

The LPS are the surface antigens of the bacteria, i.e. H. the contact of the human and animal immune system with the bacterial cell leads to the formation of antibacterial antibodies, which are predominantly against LPS structures are directed.

Furthermore, the LPS are the endotoxins of the Gram-negative bacteria, d. H. by destroying the cell, the LPS are released and develop their toxic effects. Administered in the smallest amounts, however, they cause the growth of leukocytes, stimulate them Release of interferon, interleukin and others for the immune reaction important substances and thereby cause a non-specific Resistance to bacterial and viral infections. You can also they cause regression and necrosis of certain tumors.  

More details can be found in the summary work by O. Lüderitz et al. by doing Compilation by Razin and Rottem "Current Topics in Membranes", Volume 17, 1982, pages 59 to 151.

The LPS consist of a polysaccharide part and a lipid part, the So-called lipoid A. The KDO structures belong to the polysaccharide part and are directly connected to Lipoid A. The KDO molecules lie as Pyranoses before and are linked to either via the glycosidic bonds Lipoid A or other KDO units connected.

For the synthesis of LPS or its KDO-containing substructures, one is if you want to link a KDO unit glycosidically, to KDO derivatives instructed at least positions 4, 5, 7 and 8 by Protective groups are blocked, the keto group in the 2 position and the Hydroxy function in position 6 but remain unprotected.

KDO derivatives of the general type are particularly suitable as building blocks Formula V, since the acetal protecting groups in the 4,5-position are different Stability towards the protective groups in the 7.8 position exhibit. By choosing suitable conditions, a these acetal protecting groups are split off, which means more Reaction centers are released.

However, these connections are so far only in special cases and on been relatively cumbersome.

T. Shiba et al., Tetrahedron Lett., Vol. 28, 49, 6235 (1987) in their synthesis from a fully protected D-mannitol derivative, which carries a trifluoromethanesulphonate group in the 1-position, P.A.M. van der Klein et al., Tetrahedron Lett., Vol. 30, 40, 5477 (1989) similarly a D-mannitol derivative that has the hydroxy groups forms a cyclic sulfate in the 1- and 4-positions. In both Cases, the KDO derivatives are converted by reacting the above D-mannitol Derivatives with deprotonated dithioacetals from glyoxalic acid esters receive.

The present invention was therefore based on the object, KDO and To make KDO derivatives V more accessible and new intermediaries to provide products.

Accordingly, the D-mannose derivatives I and the Phosphonium salts III found.  

In addition, processes for the preparation of compounds I and III and found for the preparation of the KDO derivatives.

The compounds according to the invention can be obtained as follows:

a) Preparation of the compounds I in which X is oxygen (Connections Ia)

To do this, oxidize a mannitol IV

under mild conditions, preferably at 0-60 ° C, in one organic solvents with a mild oxidizing agent such as preferably dimethyl sulfoxide or pyridinium chlorochromate.

If water is generated when using these oxidizing agents, it is recommended to bind the water, e.g. B. by sharing an organic anhydride such as acetic anhydride.

Either the reagents themselves or inert ones serve as solvents Liquids such as chlorinated hydrocarbons, tetrahydrofuran, benzene, Toluene or dimethylformamide. The insulation is removed volatile constituents of the reaction mixture preferably by distillation under a pressure of 0.1-30 mbar recommends not to let the temperature rise above 60 ° C.

Purification by column chromatography enables Ia to be purified represent. However, this is not the case for the further implementation of Ia absolutely necessary, d. H. one can also use the reaction mixture or run out of the residue obtained by distillation.

The starting compounds IV are from the compounds VIa (see, for example T. Shiba et al., Tetrahedron Lett., Vol. 28, 49, 6235-8 (1987)) the following reaction steps are available in a manner known per se:

• i) Selective protection of the OH group in the 1-position of compound VIa with a bulky residue, see e.g. E.g .: P. Zimmermann, RR Schmidt, Liebigs Ann. Chem., 663 (1988)
• ii) Aryl methylation of compound VIb in the 4-position, see e.g. E.g .: HG Fletcher Jr., Meth. Carbohydr. Chem., 2, 166 (1963) and literature cited therein.
• iii) Removal of the protective group in the 1-position of compound VIc, see e.g. E.g .: A. Thompson, ML Wolfrom, E. Pacsu, Meth. Carbo hydr. Chem., 2, 215 (1963) and literature cited therein.

b) preparation of the compounds I in which X is a radical II, where R⁵ is CH₂Ar (compounds Ib)

The compounds Ib are obtained by reacting the compounds Ia with the Phosphonium salts III in the presence of a base in an inert Solvent, preferably methylene chloride, obtained at 0-60 ° C. As bases the sodium alcoholates NaOCH₂Ar are preferred turns.

Then the reaction mixture is mixed with water, the organic phase and works analogously to the implementation of IV to Ia on.

c) preparation of the compounds I in which X is a radical II, where R⁵ is C₁-C₆-alkyl (compounds Ic)

The compounds Ic are made from the compounds Ib by reaction with C₁-C₆ alcoholates R⁵-O⊖ in an inert solvent, preferred Methylene chloride, or implemented in alcoholates R⁵-OH at 0-40 ° C. The Working up is carried out analogously to the conversion from IV to Ia.

d) Preparation of the compounds III

To do this, one first uses glyoxalic acid hydrate in the presence of catalytic Amounts of an acid with an alcohol ArCH₂-OH to the ester acetal

around.

Strong mineral acids such as sulfuric acids and are suitable as acids Sulfonic acids such as p-toluenesulfonic acid. Preferably you take the Reaction at 20 to 120 ° C before, it being recommended that the water of reaction to distill off continuously. It is convenient to drink alcohol in an excess of about 1 to 5 mol over the glyoxalic acid hydrate to use.

When the reaction has ended, the excess alcohol is distilled off and sets the residue at 0 to 80 ° C to replace one of the ArCH₂-O groups by a halogen Z with a carboxylic acid halide, preferably acetyl bromide to.  

The halogen compound thus obtained

is then at 20 to 120 ° C in an inert solvent such as preferred Diethyl ether or toluene with the equimolar amount of tri phenylphosphine implemented, the phosphonium salt III precipitates. The phosphonium salt can be used without further purification will.

e) Preparation of the compounds V

These compounds are obtained by hydrogenolytic cleavage of all -CH₂Ar groups from the compounds Ib or Ic. Preferably you take the hydrogenation at 10-50 ° C and 1 to 10 bar hydrogen pressure in one neutral inert solvents such as ethyl acetate or methanol. As Hydrogenation catalyst is particularly suitable for palladium / activated carbon. To Separate the catalyst, the solvent and the resulting Compound ArCH₃ can the product of the process by crystallization or chromatographic methods can be cleaned.

It is advisable to carry out all operations, with the exception of the hydrogenations, under an inert gas atmosphere.

With regard to the simplest possible procedure and the Further conversions from V to KDO preparations are called protective groups

preferred those that differ from acetone (R¹-R⁴ = Me), from diethyl ketone (R¹-R⁴ = Et), from cyclopentanone (R¹ + R² and R³ + R⁴ = 1,4-tetramethylene) or from Derive cyclohexanone (R¹ + R² = 1,5-pentamethylene).

Ar preferably denotes phenyl and also methylphenyl, ethylphenyl, Methoxyphenyl or ethoxyphenyl.

Z is preferably bromine, and R⁵ in Ic represents a methyl group.

The present invention enables the economical synthesis of KDO derivatives Va and Vb, which in turn are used to build drugs can s. see: S. Kusumoto et al., Pure Appl. Chem., 61, 461 (1989) and literature cited there.  

Examples Example 1 Preparation of 4-O-benzyl-2,3: 5,6-di-O-isopropylidene-D-mannose, Ia / 1 (I; X = O; Ar = Ph; R¹-R⁴ = Me)

A solution of 10.9 g (31 mmol) of 4-O-benzyl-2,3: 5,6-di-O-isopropylidene-D- mannitol (IV / 1), 90 ml of dimethyl sulfoxide and 55 ml of acetic anhydride Maintained at 25 ° C for 15 hours and then on a rotary evaporator 16 mbar freed from the volatile components. The residue was by flash chromatography [silica gel 60, particle size 40 μm, petroleum ether / Ethyl acetate (3: 1)] cleaned. The main fraction fell in as a colorless oil 81% yield.

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for connection Ia / 1:

1 H-NMR (250 MHz, CDCl₃):
δ = 1.35 (s, 6H, 2 Me)
1.41, 1.56 (2s, 6H, 2 Me)
3.82-4.61 (4m, 6H, 2-H, 3-H, 4-H, 5-H, 6-H, 6′-H)
4.23, 4.93 (2d, 2H, OCH₂Ph, J = 11.3 Hz)
7.27-7.33 (m, 5H, Ph)
9.52 (d, 1H, CHO, J = 1.9 Hz)

The precursors were made as follows:

i) Preparation of 2,3: 5,6-di-O-isopropylidene-1-O-pivaloyl-D-mannitol VIb / 1 (VIb; R¹-R⁴ = Me; R = pivaloyl)

A solution of 30 g (115 mmol) 2,3: 5,6-di-O-isopropylidene-D-mannitol (VIa; R¹-R⁴ = Me), 200 ml methylene chloride, 22 ml pyridine and 17 ml Pivaloyl chloride was held at 25 ° C for 12 hours. Then the Solution diluted with 200 ml chloroform, washed with water, dried and on the rotary evaporator at 16 mbar of the volatile components exempted. The residue was determined by flash chromatography [Silica gel 60, particle size 40 microns, petroleum ether / ethyl acetate (3: 1)] cleaned. The main fraction was obtained as a colorless oil in 94% yield.

[α] = - 5.2 ° (c = 1, CHCl₃)

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for compound VIb / 1:

1 H-NMR (250 MHz, CDCl₃):
δ = 1.35, 1.39, 1.40, 1.51 (4S, 12H, 4 Me)
2.3 (bs, 1H, OH)
3.57 (d, 1H, 4-H)
3.99-4.43 (2m, 7H, 1-H, 1′-H, 2-H, 3-H, 5-H, 6-H, 6′-H)

ii) Preparation of 4-O-benzyl-2,3: 5,6-di-O-isopropylidene-D-mannitol, IV / 1 (IV; Ar = Ph; R¹-R⁴ = Me)

To a solution of 20.3 g (59 mmol) 2,3: 5,6-di-O-isopropylidene-1-O- pivaloyl-D-mannitol (VIb / 1), 7.5 ml benzyl bromide and 200 ml dimethyl Formamide were 1.6 g (67 mmol) of sodium hydride so for one hour added that the reaction temperature did not exceed 25 ° C. To The reaction mixture was poured onto ice for 3 hours, after which the aqueous phase extracted with ether, and the organic extracts with Washed water and then dried. By Distilling off the volatile components compound IVc obtained was dissolved in 250 ml of absolute methanol without further purification 650 mg (12 mmol) of sodium methoxide were added and the mixture was stirred at 60 ° C. for 3 hours held. Then 12 ml of water was added. The reaction mixture was freed from the volatile constituents in vacuo, and the The residue was taken up in 300 ml of chloroform. The organic phase was washed with water and saturated sodium chloride solution, dried and freed from the volatile components. The The residue was purified by flash chromatography [silica gel 60, particle size 40 µm, petroether / ethyl acetate (1: 1)] cleaned. The main fraction fell in 53% yield.

The volatile constituents were distilled off using a Rotary evaporator at a pressure of 16 mbar.

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for compound IV / 1.

1 H-NMR (250 MHz, CDCl₃):
δ = 1.33, 1.37, 1.40, 1.50 (4S, 12H, 4 Me)
2.65 (bs, 1H, OH)
3.7-4.26 (4m, 8H, 1-H, 1′-H, 2-H, 3-H, 4-H, 5-H, 6-H, 6′-H)
4.75, 4.82 (2d, 2H, OCH₂Ph, J = 12.4 Hz)
7.26-7.37 (m, 5H, Ph)

Example 2 Preparation of 2,6-di-O-benzyl-3-deoxy-4,5: 7,8-di-O-isopropylidene-D- benzo manno-2-octenosonate, Ib / 1 (I; X = residue II; Ar = Ph; R¹-R⁴ = Me; R⁵ = CH₂Ar)

A solution of 2 g (3.4 mmol) benzyloxy-benzyloxycarbonyl-methyl-tri phenylphosphonium bromide (III / 1) and 30 ml of methylene chloride were added dropwise with 420 mg (3.2 mmol) sodium benzylate in 1.6 ml benzyl alcohol added and kept at 25 ° C for 30 minutes. Then a solution of 1 g (2.9 mmol) 4-O-benzyl-2,3: 5,6-di-O-isopropylidene-D-mannose (Ia / 1) and 30 ml of methylene chloride were added, after which the mixture was kept for 4 hours Boiling was heated. Then 30 ml of water and ether were added, the aqueous phase extracted with ether, the combined organic phases dried and on a rotary evaporator at 16 mbar from the volatile Ingredients exempt. The residue was determined by flash chromatography [Kieselgel 60, particle size 40 microns, petroleum ether / ethyl acetate (3: 1)] cleaned. The main fraction was obtained as a colorless oil in 76% yield.

[α] = - 70 ° (c = 1, CHCl₃)

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for the compound Ib / 1.

1 H-NMR (250 MHz, CDCl₃):
α = 1.26, 1.33, 1.35, 1.42 (4S, 12H, 4 Me)
3.44, (t, 1H, 6-H, J = 2.4 Hz)
3.97-4.05 (m, 4H, 5-H, 7-H, 8-H, 8′-H)
4.45, 4.83, 4.92, 5.00, 5.09, 5.17 (6d, 6H, 3 OCH₂Ph)
4.93 (t, 1H, 4-H)
6.47 (d, 1H, 3-H, J = 7.3 Hz)
7.18-7.38 (m, 15H, 3 Ph)

Example 3 Preparation of 2,6-di-O-benzyl-3-deoxy-4,5: 7,8-di-O-isopropylidene-D- manno-2-octenosonic acid methyl ester, Ic / 1 (I; X = residue II; Ar = Ph; R¹-R⁵ = Me)

A solution of 1 g (1.7 mmol) of 2,6-di-O-benzyl-3-deoxy-4,5: 7,8-di-O- benzyl isopropylidene-D-manno-2-octenosate (Ib / 1) and 50 ml Absolute methanol was mixed with 160 mg (3 mmol) sodium methoxide. After 1 hour it was neutralized with an acidic ion exchanger, after which the filtrate on the rotary evaporator at 16 mbar of volatile Components was exempted.  

The purification was carried out by flash chromatography [silica gel 60, grain size 40 µm, petroleum ether / ethyl acetate (4: 1)]. The main fraction fell as colorless oil in 92% yield.

[α] = 57 ° C (c = 1, CHCl₃)

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for the connection Ic / 1:

1 H-NMR (250 MHz, CDCl₃):
δ = 1.27, 1.33, 1.36, 1.45 (4S, 12H, 4 Me)
3.16 (t, 1H, 6-H, J = 2.7 Hz)
3.98-4.08 (m, 4H, 5-H, 7-H, 8-H, 8′-H)
4.50 (d, 1H, OCH₂Ph, J = 11.6 Hz)
4.96-5.04 (m, 1H, 4-H, OCH₂Ph)
6.40 (d, 1H, 3-H, J = 7.6 Hz)
7.24-7.39 (m, 10H, 2 Ph)

Example 4 Production of benzyloxy-benzyloxycarbonyl-methyl-triphenylphosphonium bromide, III / 1 (III; Ar = Ph)

A solution of 20.2 g (220 mmol) glyoxylic acid hydrate, 150 ml benzyl alcohol, 200 ml of toluene and 20 drops of concentrated sulfuric acid was added while refluxing the water for 18 hours. The reaction mixture was then washed with concentrated ammonia Solution and then washed with water. The organic phase was dried and freed from the volatile components.

The residue was mixed with 35 g (280 mmol) of acetyl bromide, whereupon the mixture warmed up strongly. After cooling to room temperature the mixture is devolatilized. The residue was taken up in 250 ml ether and with 60 g (229 mmol) triphenylphosphine in 1000 ml of ether were added dropwise, resulting in a resinous precipitate formed. The solvent was decanted off and the residue 500 ml of ether were added, the product precipitating out. The yield was 68%.

The volatiles were removed using a rotary evaporator at 16 mbar.
Mp 105-107 ° C with decomposition

The measured values of the nuclear magnetic resonance spectrum below corresponded to the Expected values for compound III / 1:

1 H-NMR (250 MHz, CDCl₃):
δ = 4.94-5.23 (4d, 4H, 2 OCH₂Ph)
6.98-7.88 (2m, 25H, 5 Ph)
8.45 (d, 1H, J = 13.3 Hz)

Example 5 Preparation of 4,5: 7,8-di-O-isopropylidene-3-deoxy-α, β-D-manno-2-octulo pyranoside, Va / 1 (V; R¹-R⁴ = Me; R⁶ = H)

A solution of 0.5 g (0.85 mmol 2,6-di-O-benzyl-3-deoxy-4.5: 7.8-di-O- benzyl isopropylidene-D-manno-2-octenosate (Ib / 1) and 50 ml Ethyl acetate / methanol (1: 1) was mixed with 50 mg of 5% palladium-carbon at Nor shaken for 1 hour under a hydrogen atmosphere. The usual Working up on the process product delivered this in 93% Yield.

Example 6 Preparation of 4,5: 7,8-di-O-isopropylidene-3-deoxy-α, β-D-manno-2-octulo pyranoside methyl ester, Vb / 1 (V; R¹-R⁴ = Me; R⁵ = Me)

A solution of 0.8 g (1.6 mmol) of 2,6-O-benzyl-3-deoxy-4.5: 7.8-di-O- methyl isopropylidene-D-manno-2-octenosonate (Ic / 1) and 50 ml Ethyl acetate / methanol (1: 1) was mixed with 100 mg of 5% palladium-carbon Normal pressure shaken for 3 hours under a hydrogen atmosphere. The The usual work-up on the process product delivered this in 87% Yield.

Claims (6)

1. Derivatives of D-mannose of the general formula I in which the substituents have the following meaning:
X is oxygen or a radical of the general formula II where R⁵ represents a radical -CH₂Ar or a C₁-C₆ alkyl group,
R¹-R⁴ C₁-C₃-alkyl groups, where the radicals R¹ and R² or R³ and R⁴ can each be linked to form a 5- or 6-membered ring,
Ar is a phenyl group which can carry one or two C₁-C₄-alkyl and or C₁-C₄-alkoxy groups as substituents. 2. Phosphonium salts of the general formula III in which Z means halogen. 3. A process for the preparation of D-mannose derivatives of the general formula Ia according to claim 1 characterized in that a D-mannitol derivative of the general formula IV oxidized at 0-80 ° C with a sulfoxide or a chromium VI compound. 4. A process for the preparation of D-mannose derivatives of the general formula Ib according to claim 1 characterized in that a D-mannose derivative Ia according to claim 3 is reacted with a phosphonium salt III according to claim 2 and a base in an inert organic solvent at 0-80 ° C. 5. A process for the preparation of D-mannose derivatives of the general formula Ic according to claim 1 in which R⁵ represents a C₁-C₆ alkyl group, characterized in that a D-mannose derivative Ib according to claim 4 is transesterified with an alkali metal C₁-C₆ alkanolate at 0-80 ° C. 6. Process for the preparation of derivatives of 2-keto-3-deoxy-D-manno octonic acid of the general formula V in which R⁶ represents hydrogen or a C₁-C₆ alkyl group, characterized in that a compound I according to Claim 1, in which X represents a radical II, is catalytically hydrogenated with the elimination of all arylmethyl groups contained in the molecule.