DE2049537A1 - Arabinose derivatives - Google Patents

Description

Dr. ! ng. Ä. van der Werft Dr. F ranz Ledsrer

PATENT LAWYERS

2049537 Oct 8, 1970

RAN 4120/27

F. HoiTmanii-La Roche & Co. Aktiengesellschaft, Basel / Switzerland

Arabinose derivatives

The present invention relates to new L-arabinose derivatives of the general formula

H _Λ Η

Ö-

v- represents where R, lower

wherein X is hydrogen, lower alkyl, lower alkanoyl, or the group R

Alkyl, R ₂ denote hydrogen, lower alkyl, or together with R, lower alkylene and R, denote hydrogen or lower alkyl and R ^, and Rp- each individually 109819/2039

Hydrogen, lower alkyl or IU and R ₁ - to ·? together represent lower alkylene,

and a new process for their production and for the production of 5-deoxy-L-arabinose.

Lower alkyl radicals present in the above formula I are preferably those having 1 to 4 carbon atoms, for example methyl, ethyl, isopropyl, etc. Lower alkanoyl radicals preferably have 1 to 4 carbon atoms, for example formyl, acetyl, propionyl, isobutyryl. If R _{1 and R p represent} a lower alkylene radical, this radical preferably bears 3 or 4 carbon atoms. R _{1 mean} . and R, - together a lower alkylene radical, this radical preferably bears 4 or 5 carbon atoms. Examples of the groups R.OCRJFt -, - are: methoxymethyl, 1-ethoxyethyl, 1-isopropoxy-ethyl, 1-methoxy-1-methyl-ethyl, tetrahydrofuran-2-yl, 2-methyl-tetrahydrofuran-2-yl, Tetrahydropyran-2-yl.

The inventive method is characterized in that a compound of the general formula

II

Ö — C — R,

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wherein X, R ^ and R ₁ - have the above meaning / treated with a hydrogenating agent and in a compound of the formula I thus obtained, optionally in a manner known per se, the protective group J> CC and a

R ₅ \

optionally present protective group X splits off.

The starting compounds of the formula II are new and likewise a subject of the present invention. You can for example, can be produced starting from D-glucose.

In the first stage, D-glucose is reacted in the usual way with a carbonyl compound of the formula J ^ -C = O, in which R ₁ and Rt- have the above meaning. Examples of such carbony compounds are formaldehyde, acetaldehyde, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc. Dimethyl ketone (acetone) is preferably used. The reaction is preferably conducted in the presence of water g dehydrating agents, for example, carried out in the presence of anhydrous copper sulphate or in concentrated sulfuric acid, and in the presence of an organic solvent, such as acetone. The reaction succeeds even at room temperature. A compound of the general formula is obtained

1Ü9M9 / 2039

III

0-CR ₁

wherein R ₂ and R ₁ - have the meaning given above,

* R ₄

from which then the group ^ CZ ^ in the 5 »6-O position

is split off. This is achieved, for example, by heating with copper (II) acetate in aqueous solution or by careful heating with a dilute mineral acid or a lower alkanecarboxylic acid in an optionally aqueous organic solvent, e.g. in a lower alkanol. If you use an acid, the port step will be the reaction is continuously monitored, e.g. with the help of a thin-layer chromatogram, and interrupted in good time, but if the protective group is split off in the 5 »6-O ~ position the protective group in the 1,2-0 position is still intact.

The 1,2-0-protected <- <- D ~ glucofuranose obtained is now subjected to glycol oxidation. During this oxidation the hydroxymethyl group is split off in a 6-position. Part of the intermediate 4-formyl compound experiences a spontaneous dimerization, while the other part spontaneously condenses with the formaldehyde formed

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will. The oxidation is carried out with the aid of one of the usual glycol oxidizing agents. The oxidizing agent used is, for example, lead tetraacetate, red lead and acetic acid, lead tetraphosphate, silver carbonate or an alkali metal periodate such as sodium periodate. The oxidation is conveniently carried out in an organic solvent such as acetic acid or benzene at a temperature between about room temperature and about 50 ⁰ C.

The oxidation product obtained is then reduced. As a reducing agent comes through above all Raney nickel catalyzed hydrogen into consideration. Other reducing agents that can be used are complex metal hydrides such as for example lithium aluminum hydride, sodium aluminum hydride or sodium borohydride. The reduction is expediently carried out in a lower, optionally aqueous alkanol at a temperature of about 0 ° -100 ° C. The hydrogenation with hydrogen and Raney nickel is preferably used at elevated pressure, for example carried out in a pressure range of up to about 60 atmospheres,

formula

In this way compounds of the general ones are obtained

HIGH

IV

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where Rl and R_ have the meaning given above, which are new and as such also the subject of the present application.

The compounds of formula IV are also made from

D-xylose by reacting with a Carbony! Compound of the

R ₁ ,
Formula ^ -C = O, in a manner analogous to the implementation above

^R 5
indicated with D-glucose, available.

The compounds of the formula IV are then combined with a compound of the formula

Y-HaI 'V

wherein Y is a substituted sulphonyloxy group, for example Mesyloxy, phenylsulfonyloxy or tosyloxy and Hai denote a halogen atom, in particular chlorine or bromine,

implemented. This reaction is preferably carried out in a basic, organic solvent, such as, for example, pyridine, at about 0 ^° C. to about room temperature. Compounds of the general formula are obtained

Y-CH

VI

0 — C — R ₁

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wherein Y, Rn and Rp. have the meaning given above to have.

In the compounds of the formula VI, the hydrogen atom in the 5-O position is now exchanged for one of the X protecting groups. The protective group is introduced in a manner known per se. Lower alkanoyl groups are introduced, for example, by reaction with a corresponding acid halide or acid anhydride in a basic, organic solvent, such as pyridine, at low temperature, for example at ⁰ ° C. to about room temperature. The heterocyclic radicals R ₁ OCRpR _n , - are introduced, for example, in an inert, non-polar solvent, such as benzene or ether, by treatment with an excess of the corresponding cyclic ether (eg dihydropyran, dihydrofuran). The reaction is accelerated by the presence of catalytic amounts of p-toluenesulfonic acid. The temperature is not critical, but it is expediently between about room temperature and the boiling point of the reaction mixture. The non-heterocyclic radicals R ₁ OCRpR - can, for example, by reaction with the corresponding halogenated ether (for example methoxymethyl chloride, 1-ethoxyethyl bromide, etc.) in the presence of anhydrous sodium carbonate and an inert solvent at elevated temperature, for example at boiling point , are introduced. Lower alkyl groups are expediently introduced in the manner

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that you have the corresponding iodine (e.g. methyl iodide) in a considerable excess is added and the mixture, after the addition of pulverized potassium hydroxide, is brought to about 80-150 ° C. with stirring heated.

The compounds of the general formula obtained

Y-CH

VII

0 — C — fl.

wherein Y, FU and R ^ have the meaning given above and X, lower alkyl, lower alkanoyl, or the group FLOCFUFU- is, in which R, lower alkyl, Rp is hydrogen, lower alkyl or together with R, lower alkylene and R is hydrogen or lower Mean alkyl,

can be converted into the starting material of Formula II in two different ways. If X is lower alkanoyl, the starting compounds of the formula II are obtained via a 5-iodine (or bromine) compound. By heating a compound of the formula VII, in which X. is lower alkanoyl, with an alkali metal iodide or bromide, or with the corresponding ammonium salt, in a lower aliphatic ketone, preferably at reflux temperature, one obtains a

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Compound of the general formula

Z-CH.

Rr

VIII

wherein R ₂ ^ and R ₁ - have the meaning given above, Z is bromine or iodine and X is lower alkanoyl.

If a volatile ketone, such as acetone, is used as the solvent, it is preferred to work in an autoclave. The temperature is advantageously at about 100-150 ⁰ C.

The compounds of the above formulas VI, VII and VIII are new compounds and as such are also an object of the present invention.

The resulting compounds of formula VIII are then by treatment with silver fluoride into the desired starting compounds of the general formula

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Ha

2 — Ri

wherein X ", R ^, and R ₁ - have the meaning given above,

convicted. The reaction takes place in an anhydrous, basic Solvent such as pyridine, preferably carried out at about room temperature.

If desired, the protective group X_ in the compounds of the formula Ha obtained can be split off by treatment with a catalytic amount of an alkali metal alcoholate of a lower alkanol, dissolved in a lower alkanol. For example, a methanolic sodium methylate solution or similar solutions of lower alkanolates are used. The protective group can also be split off by treatment with dry ammonia dissolved in a lower alkanol. The temperature of the reaction is expediently between about 0 ^° C. and about room temperature.

Compounds obtained of the general formula VII, in which X, lower alkyl, or the group R, OCRpR., - is, can be converted directly into the desired starting compounds of the general formula

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lib

where R |. and R ₁ - have the meaning given above and X-, lower alkyl or the group R, OCR R ^ ₅ - represents, in which R ,, R ₂ and R, have the meaning given above,

be transferred. This can be done by mixing the mentioned compounds of the formula VII with an alkali metal alcoholate of a lower alkanol, in particular with potassium tert-butoxide, in the presence of a mixture of one lower alkanol and a basic organic solvent, for example pyridine, at about room temperature treated.

The inventive hydrogenation of the starting compounds of the formula II is preferably carried out with catalytically activated Hydrogen carried out as a hydrogenation catalyst palladium / carbon is preferred. Other hydrogenation catalysts such as platinum dioxide can also be used or Raney nickel. Hydrogenation is preferred at Atmospheric pressure in a non-acidic organic solvent, e.g. in a lower alkanol, in a lower one

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Alkyl esters of a lower alkanecarboxylic acid, such as ethyl acetate, or in a lower, aliphatic or alicyclic ether, such as dimethyl ether, dioxane or tetrahydrofuran, carried out. The reaction temperature is not critical; however, it is expediently in the range from about room temperature to about 10O ⁰ C.

Compounds of the formula I obtained can be freed from the “CCT” protective group and from any protective group X which may be present in a manner known per se. 5-deoxy-L-arabinose is then obtained. If the protective group X represents lower alkanoyl, this can be split off in the same way as indicated above for the removal of protective groups Xp from compounds of the formula Ha. The group _R ^ -CC ^ is retained and can then be separated by treatment with acidic agents, for example by heating with a dilute mineral acid or with a lower alkanecarboxylic acid in an optionally aqueous, organic solvent, for example in a lower alkanol.

If the protective group X of the compounds of the formula I obtained is lower alkyl or the group R, OCRpR., -, so can this, as well as the group ~

5 by treating with acidic agents as above for cleavage

1 098 1 9/2039

give the group Z ^ CL ^to ^ ^e , be split off. The groups R ₁ OCR ₀ R -, - are split off under mild conditions; however, more energetic conditions (longer time) are required to cleave the lower alkyl groups.

Another method for splitting off a group R ₁ OCRpR, - is to continue the hydrogenation described above. The group ^^ Cc ^ 'can then, as explained above, be split off by treatment with acidic agents.

The compounds of general formula I can thus, as described above, easily convert into 5-deoxy-L-arabinose be transferred. This in turn is a valuable building block for the production of biopterin as well as for the hydrogenation products of this compound, the precursors for the cofactor of animal phenylalanine hydroxylase and represent tryptophan hydroxylase.

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- 14 - 20A9537

example 1

6 g of 3-0-acetyl-5-deoxy-1,2-O-isopropylidene-β-L-threopent-4-enofuranose are dissolved in 100 ml of methanol and after adding 2 g of 5 # palladium / carbon at room temperature hydrogenated with hydrogen. The reaction mixture is then filtered and concentrated to dryness. The residue is suspended in ether and filtered. The filtrate is concentrated to dryness. 3-O-acetyl-5-

2 * 5 ° deoxy-1,2-0-isopropylidene-β-L-arabinofuranose, talr / = + 8.25 ° (c = 1.915; methanol).

7.1 g of 3-0-acetyl-5-deoxy-1,2-0risopropylidene-β-L-arabinofuranose are dissolved in 200 ml of absolute methanol and 10 ml of 0.1N methanolic sodium methylate solution are added in a round bottom flask. The flask is sealed airtight and allowed to stand at room temperature. After 5 hours, Amberlite IR 120 (H ⁺ form, washed with excess methanol) is added to the reaction mixture. The mixture is stirred until it reacts neutral and then filtered. The filter residue is washed with methanol. The combined filtrates are concentrated to dryness. The remaining 5-deoxy-1,2 ~ 0-isopropylidene-β-L-arabinofuranose crystallizes at room temperature. The crystals are triturated with low-boiling ether / petroleum ether (7: 3), filtered, washed with 7: 3 ether / petroleum ether and then with low-boiling petroleum ether. The compound thus obtained melts

10 9819/2039

after drying under reduced pressure at 80 ° -82 °.

Another amount of 5-deoxy-1,2-0-isopropylidene-ß-L-

furanose

arabino / can be obtained from the mother liquor in the same way. Melting point 78-80 °.

= -10.8 ° (c = 0.297 / methanol).

Analysis: calculated for found ^C 8 ^H 14 ° 4 C. 55.16 55.17 H 8.10 7.94

The j5-O-acetyl-5-deoxy-1,2-0-isopropylidene-ß-L-threo-pent- ' ^{ l-enofuranose used as starting material can be prepared as follows:

50 gl, 2: 5,6-di-0-isopropylidene-aD-glucofuranose g

(made by treating a-D-glucose with acetone in Presence of sulfuric acid) are suspended in 1500 ml of water and 0.5 g of copper (II) acetate is added while stirring. The solution is refluxed for about 5 hours heated. After boiling for half an hour, a sample (approx. 2 ml) is evaporated to dryness under reduced pressure. If the If the residue melts at 153-154 ° C, the boiling process is terminated. About 2 g of activated charcoal are then added to the reaction solution while stirring, the mixture is stirred for a few minutes and filtered and evaporated to dryness under reduced pressure. The "pro-

IU9 «19/2039

The product is reduced to constant weight under reduced pressure dried at 40-5O ° C. 1,2-0-Isopropylidene-a-D-glucofuranose is obtained as a gray-green colored crystal mass that melts at 153-154 °.

22.0 g of 1,2-isopropylidene-a-D-glucofuranose are in Suspended 100 ml of glacial acetic acid and added 50 g of lead tetraacetate over the course of 15-20 minutes while stirring. The beginning, exothermic oxidation is achieved by cooling to a temperature of 40 ° C held. After the reaction has ended, the reaction mixture is stirred for a further 1 hour. The received, slightly cloudy solution is evaporated at approx. 40 ^ 3. The received The residue is taken up in a little water and extracted twice with 150 ml of ethyl acetate. The combined ethyl acetate solutions are washed neutral with sodium bicarbonate solution, dried over sodium sulfate and evaporated. You get a white one amorphous oxidation product (dimer of 1,2-0-isopropylidene-a-D-xylo-pentodialdo-1,4-furanose or the condensation product of this compound with the formaldehyde formed) for the next stage is used directly.

90.0 g of the amorphous oxidation product obtained above are dissolved in a mixture of 750 ml of ethanol and 250 ml of water and with 25 g of Raney nickel at 100 ° C. and 60 atmospheres for 5 hours hydrogenated. The catalyst is filtered off. The piltrate is evaporated at 40 ° C. under reduced pressure. The residue, a colorless syrup, is distilled under greatly reduced pressure. 1,2-0-Isopropylidone-a-D-xylofuranose is obtained, which

1 night 3 H 1 bottle / 2 0 3 9

boils at 155-160 ° / 0.03 torr.

Analysis ; calculated for found

C 50.52 50.53

H 7j42 7, ^ 2

6.0 g of 1,2-0-isopropylidene-oc-D-xylofuranose are in

Dissolve 50 ml of absolute pyridine and, while cooling with ice, and M

A solution of 6.2 g of p-toluenesulphonyl chloride in 25 ml of absolute benzene is added dropwise over the course of 30 minutes. After standing at room temperature for 12 hours, most of the pyridine is distilled off at 35-4o ° C. The residue is mixed with 150-200 ml of water and shaken vigorously for 15-20 minutes. The white crystals which precipitate are filtered off and washed with cold, distilled water until they are free of pyridine, then dried at 40 ° C. under reduced pressure and then recrystallized from ethyl acetate / petroleum ether. This gives l, 2-0-isopropylidene-5-0-tosyl-D-xylofuranose, melting at 135-136 ⁰ C.

Analysis; calculated for

^C 15 ^H 20 ° 7 ^S C 52 _; 32

H 5.83

S 9, 31

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found 39 52, 97 5 / 25th 9;

100 gl ^ -Isopropylidene-SO-tosyl-aD-xylofuranose are dissolved in 650 ml of absolute pyridine and, with exclusion of moisture, 92.5 ml of acetic anhydride are added dropwise over the course of 15 minutes. The temperature temporarily rises to 28 ° C, but drops to 25 ° C after a further 15 minutes. The reaction mixture is stirred for 12 hours at room temperature. The reaction mixture is evaporated to dryness. The residue is dissolved in 200 ml of methylene chloride, about 300 ml of ice water are added and the mixture is stirred for half an hour. The organic phase is then washed with ~ *> n hydrochloric acid and then with sodium bicarbonate solution, dried over sodium sulfate and filtered. The filtrate is concentrated to dryness. The residue is dried at 80 ° C. under greatly reduced pressure. 3-0-Acetyl-1,2-O-isopropylidene-5-O-tosyl-aD-xylofuranose is obtained, which behaves uniformly on the thin-layer chromatogram (silica gel; petroleum ether / acetone 7: 3) ϊ [α] ^ ⁵ = - 19 »8 ° (c = 1.38> chloroform).

Analysis : calculated for

^C 17 ^H 22 ° 8 ^S C 52.84

H 5.74

S 8.30

The product is processed further without further purification.

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found , 90 52 , 76 5 , 19th 8th

A solution of 112.1 g of 3-0-acetyl-1,2-0-isopropylidene-5-O-tosyl-a-D-xylofuranose in 1700 ml of methyl propyl ketone added 167 g of sodium iodide. The mixture is stirred Heated to boiling under reflux conditions for 16 hours. The reaction mixture is then concentrated to dryness. The residue is extracted with approx. 300 ml of benzene. The benzene extract-will filtered. The filtrate is concentrated. The obtained crude 3-0-acetyl-5-deoxy-5-iodine-1,20-isopropylidene-a-D-xylofuranose is purified by adsorption on 20 times the amount of silica gel (0.2-0.5 mm) (eluent benzene / ether 9: 1).

The pure 3-0-acetyl-5-deoxy-5-iodine-1,2-O-isopropylidene-oc-D-xylofuranose obtained melts at 62 ° 0; [α] _β = -46.7 ° (c = 1.7; chloroform).

Analysis : calculated for found

C ₁₀ H ₁₅ O ₅ J.

C 35.11 35.59

H 4.42 4.56

75.3 S 3 ~ 0 ~ acetyl-5-ciesoxy-5-iodine-1,2-0-isopropylidenoc-D-xylofuranose, 90.5 S finely divided silver fluoride and 75Ο ml pyridine (dried over barium oxide) are combined Shaken under lock and key and with exclusion of light for 16 hours. The reaction mixture is poured into about 2500 ml of ether with stirring poured and mixed with activated charcoal. After stirring for half an hour, the mixture is filtered. The filtrate is with ice-cold 3n Hydrochloric acid and then mixed with sodium bicarbonate solution

10 9 819/2039

calculated for found ^C 10 ^H 14 ° 5 56.07 56.08 6.59 6.59

to wash. The solution is dried over sodium sulfate, filtered and concentrated to dryness. The remaining J> -0- acetyl-5-deoxy-1,2-0-isopropylidene-β-L-threo-pent-4-enofuranose, a colorless liquid, is purified by distillation at 80 ° C / 0.05 mm . njp = 1.4548; [a] Jp = * 18.3 ° (c = 0.45; chloroform).

Analysis :

Example 2

42.2 g of 5-deoxy-1,2-0-isopropylidene-ß-L-arabinose are slurried in 1000 ml of 10 # acetic acid and put on the steam bath Heated for 1 1/2 hours. The reaction mixture is then concentrated to dryness. The residue is used several times Methanol / benzene 1: 1 slurried and concentrated again in each case. The residue is under greatly reduced pressure at 60.degree dried. The obtained 5-deoxy-L-arabinose, a yellowish, ches OeI, is adsorbed on 20 times the amount of silica gel 0.2-0.5 mm (eluent: chloroform / methanol 9: 1) cleaned. The 1 liter practions, which are uniform in the thin-layer chromatogram, are combined and reduced under greatly reduced conditions

Print dried at 60 ° C. Pure 5-deoxy-L-arabinose is obtained; [cx] 25 ° ₌ -38.8 ° (c = 0.294; ethanol). R ₁ = 0.6 ^ (Whatman-

Paper; n-butanol: glacial acetic acid: water-50: 1505).

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Example 3

19. * 1 g of 5-deoxy-1,2-0-isopropylidene-3-0- (tetrahydropyran-2-yl) -β-L-threo-pent-4-enofuranose in 500 ml of methanol is mixed with 1.5 g 5 ^ palladium carbon is added and the mixture is hydrogenated with hydrogen at room temperature while shaking. After the uptake of hydrogen has ended, the reaction mixture is filtered. The filter residue is washed with methanol. The filtrate is concentrated to dryness. A crystalline residue remains, which is slurried with ether / petroleum ether 3: 7. The suspension is filtered and washed with ether / petroleum ether 3: 7 and then with petroleum ether. The 5-deoxy-1,2-0-isopropylidene-β-L-arabinofuranose thus obtained melts at 78-80 ° C. ία]? ⁵ ° = -12.58 ° (c = 0.183 j methanol).

Analysis : calculated for found

C 55.16 55.20

H 8.10 8.12

Crystalline 5-deoxy-1,2-0-isopropylidene-β-L-arabinofuranose can be obtained from the mother liquor in the same way as described above be won.

The 5-deoxy-1,2-0-isopropylidene-3-0- (tetrahydropyran-2-yl) -β-L-threo-pent-4-enofuranose used as starting material can be made as follows:

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58.8g l, 2 <) - isopropylidene-5-0-tosyl-D-xylofuranose are poured over with 13OO ml of absolute benzene and brought into solution by heating on the steam bath. The solution is mixed with 40 ml of dihydropyran (distilled over sodium) and 0.4 g of p-toluenesulfonic acid monohydrate and heated for 10 minutes. After cooling, the mixture is neutralized with sodium bicarbonate solution. The benzene solution is dried over sodium sulfate, filtered and concentrated to dryness. The residue is dissolved in about 200 ml of warm glacial acetic acid, low-boiling petroleum ether is added until it starts to become cloudy and the mixture is cooled to room temperature. After standing in the cold for one hour, the crystals formed are filtered off, washed with low-boiling petroleum ether / ethyl acetate 1: 4 and then with petroleum ether and dried at 40 ° -45 ° C. under reduced pressure. The obtained l, 2-0-isopropylidene-3-0- (tetrahydropyran-2-yl) -5-0-tosyl-D-xylofuranose melts at 87-89 ⁰ C.

calculated for found ^C 20 ^H 28 ° 8 ^S .56.06 55.97 6.59 6.52 7.48 7.28

A mixture of 50 g of 1,2-0-isopropylidene-3-0- (tetrahydropyran-2-yl) -5-0-tosyl-cc-D-xylofuranose, 500 ml of absolute pyridine (dried over barium oxide) 500 ml of tert-butanol and 65 g of potassium tert-butoxide are stored for 16 hours in the absence of air

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shaken. The reaction mixture was then poured into 2000 ml of ethanol and neutralized by introducing carbon dioxide gas while stirring (duration about 1 hour). The mixture is then concentrated to dryness. The residue is dissolved in about 1000 ml of water and extracted three times with 500 ml of ether. The combined ether extracts are washed with ice-cold ^5N hydrochloric acid and then with sodium bicarbonate solution. The ether solution is dried over sodium sulfate, filtered and concentrated to dryness. The crude ^ -deoxy-ljS-O-isopropylidene - ^ - O- (tetrahydropyran-2-yl) -ß-L-threo-pent-4-enofuranose obtained is adsorbed on 20 times the amount of silica gel ( 0.2-0.5 mm) (eluent: benzene / ethyl acetate 95-5).

Analysis : calculated for found

^C 13 ^H 20 ° 5

C 60.92 61.19

H 7.87 8.09

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Claims (12)

Claims 1. Process for the preparation of L-arabinose derivatives of the general formula H ^ C H 0 — C — R ₁ wherein X is hydrogen, lower alkyl, lower alkanoyl or the group R.OCRpR ^ - where R, lower alkyl, Rp is hydrogen, lower alkyl or together with R, lower alkylene and R ^. Signify hydrogen or lower alkyl and R ₁ . and R ₁ - each individually hydrogen, lower alkyl, or Rj. and R ^. together represent lower alkylene, and of 5-deoxy-L-arabinose, characterized in that one is a compound of the general formula II 109819/2039 wherein X, R ₂ , and Rp- have the meaning given above to have, treated with a hydrogenating agent and in such a way
obtained compound of the formula I optionally in a known V / eise the protective group ^ "CtT and a given R ₅ \ optionally present protecting group X splits off. 2. The method according to claim 1, characterized in that that the hydrogenating agent is hydrogen and a ^ Hydrogenation catalyst uses. 3. The method according to claim 2, characterized in that that a palladium-carbon catalyst is used. 4. The method according to one of claims 2 or j5 *
characterized in that the reaction is carried out at about room temperature. 5 · The method according to any one of claims 1-4, characterized
characterized in that 3-0-acetyl-5-deoxy-1,2-0-isopropylidene-ß-L-threo-pent-4-enofuranose is hydrogenated, the obtained
3-0-acetyl-5-deoxy-1,2-0-isopropylidene-ß-L-arabinofuranose
optionally treated with an alkali metal alcoholate of a lower alkanol and the resulting 5-deoxy-1,2-0-isopropylidene-ß-L-arabinofuranose optionally with a
acidic agents treated. 109819/2039 6. The method according to claim 5 *, characterized in that that one sodium methylate, sodium ethylate, potassium methylate or Potassium ethylate is used. 7. The method according to claim 5 *, characterized in that that dilute acetic acid is used as an acidic agent, 8. The method according to any one of claims 1-4, characterized in that 5-deoxy-1,2-0-isopropylidene-3-0- (tetrahydropyran-2-yl) -ß-L-threo-pent-4- enofuranose hydrogenated and the 5 "de ^sox yl» 2-0 - isopropylidene / 3-L ~ arabinofuranose obtained, if necessary treated with an acidic agent. 9. The method according to claim 8, characterized in that dilute acetic acid is used as the acidic agent. 109819/2039 10. L-arabinose derivatives of the general formula where X is hydrogen, lower alkyl, lower alkanoyl or the group R ₁ OCR ₂ Ry, where R _{1 is} lower alkyl, R _{0 is} hydrogen, lower alkyl, or together with R, lower alkylene and R ^. Denotes hydrogen or lower alkyl and Rj ₁ , and Rj- each individually represent hydrogen, lower alkyl or Rj, and R ₁ - together represent lower alkylene. 11. 3-0-Acetyl-5-deoxy-1,2-0-isopropylidene-β-L-arabinofuranose. 12. 5-deoxy-1,2-0-isopropylidene-ß-L-arabinofuranose, 109819/2039 ORIGINAL INSPECTED