EP1525197A1

EP1525197A1 - Method for producing highly pure hydroxy indolyl glyoxylic acid amides

Info

Publication number: EP1525197A1
Application number: EP03766389A
Authority: EP
Inventors: Hans-Joachim Jänsch; Helge Hartenhauer; Hans Stange; Norbert Höfgen; Jürgen Schäfer
Original assignee: Elbion GmbH
Current assignee: Elbion GmbH
Priority date: 2002-08-01
Filing date: 2003-07-31
Publication date: 2005-04-27
Also published as: TW200505854A; RU2005105581A; IL165949A0; PL375492A1; HRP20050201A2; JP2006503002A; AU2003255341A1; US20040063939A1; CN1671692A; US7122674B2; MXPA05001227A; CN1325490C; KR20050026095A; RU2315046C2; NO20051086L; ZA200500454B; BR0313467A; CA2493982A1; WO2004013127A1; NZ537947A

Abstract

The invention relates to a method for producing hydroxy indolyl glyoxylic acid amides in high yields and in a particularly pure form.

Description

Process for the preparation of high-purity hydroxyindolylglyoxylic acid amides

description

Technical field

The invention relates to a process for the preparation of substituted hydroxyindolylglyoxylamides of the general formula 1,

and of these in particular the compound AWD 12-281 (formula 2), which is a known inhibitor of phosphodiesterase 4 (PDE 4).

State of the art

Processes for the preparation of various indol-3-ylglyoxylamides have already been described several times. In all cases, 3-position unsubstituted indoles, which are synthesized by substitution in position 1 of a commercially available indole, were converted by reaction with oxalic acid halides into indol-3-ylglyoxylic acid hatogenides, which were then reacted with ammonia or with primary or secondary amines give the corresponding indol-3-ylglyoxylamides. (Scheme 1)

Scheme 1:

Patents US 2,825,734 and US Pat. No. 3,188,313 describe various indol-3-ylglyoxylamides which are prepared in the manner shown in Scheme 1. These compounds are used as intermediates for the production of indole derivatives formed by reductions which do not correspond to general formula 1. This also applies to the indol-3-ylglyoxylamides described in US Pat. No. 3,642,803.

Farmaco 22 (1967), 229-244 describes the preparation of 5-methoxyindol-3-ylglyoxylic acid amides. The indole derivative used is reacted again with oxalyl chloride and the resulting indol-3-ylglyoxylic acid chloride is reacted with an amine. W ei te rhinwe rd enauchim P a te nt US 6, 008, 23 1 Indol-3-ylglyoxylic acid amides and processes for their preparation. Again, the reaction steps shown in Scheme 1 are used. The reaction conditions described correspond to those used in the other sources.

A process for the preparation of substituted hydroxyindolylglyoxylamides was first described in DE 198 18 964 A1. Here, indolylglyoxylic acid amides of the formula 1 in which R ² or R ³ or R ² and R ^{3 represent} the group -OR are used, which were previously provided in a known manner according to scheme 1. The substituent -R is selected so that the desired hydroxyindol-3-ylglyoxylamides are formed by its splitting off. In general, the substituent -R for alkyl, cycloalkyl, arylalkyl, aryl, heteroaryl, acyl, alkoxycarbonyl, aryloxycarbonyl, aminocarbonyl, N-substituted aminocarbonyl, silyl, sulfonyl groups and complexing agents, such as compounds of boric acid, phosphoric acid and covalently or coordinatively bound metals such as zinc, aluminum or copper.

For the elimination of the substituent -R, both acids and bases, such as, for example, hydrobromic acid, hydrochloric acid or hydroiodic acid or sodium hydroxide solution, potassium hydroxide solution and sodium or potassium carbonate, but also activating Lewis acids, such as, for example, AICI ₃ , BF ₃ , BBr ₃ or LiCI, are used , The cleavage reaction takes place in the absence or in the presence of additional activators, such as ethane-1, 2-dithiol or benzyl mercaptan, and ether cleavages, using hydrogen, under elevated pressure or under atmospheric pressure, in the presence of a suitable catalyst, such as, for example, palladium or iridium catalysts , The technical description of the application examples, in particular the preparation of compound 2, which is the substance AWD 12-281 - a known inhibitor of PDE 4 - was concentrated on the elimination of a methyl or an acetyl group. Due to the superior yield, the elimination of the methyl group must be considered as the preferred variant.

The already known processes for the preparation of indol-3-ylglyoxylamides according to Scheme 1 and the subsequent cleavage of suitable leaving groups according to DE 198 18 964 A1 are per se suitable for the preparation of hydroxyindol-3-ylglyoxylamides of the formula 1 in the laboratory. However, the indole derivatives used as starting materials, such as, for example, methoxyindoles or acetoxyindoles, lead to considerable technical difficulties when using the process for producing these compounds in the quality required for a new medicament. This is particularly true for applications on a semi-technical or technical scale. Thus, the intermediates according to scheme 1, in particular the 1 - (4- F u u rb e n cyl) - derivatives required for the production of AWD 12-281 (formula 2), s e h r sc l e c ht i s o l i e rb a r. For example, 1 - (4-fluorobenzyl) -5-methoxyindole has to be isolated using an extractive process in order to achieve a quality that can be used industrially. The yield is inevitably reduced by such complex processes.

Regardless of these technological disadvantages, it should be noted that the hydroxyindol-3-ylglyoxylamides of the formula 1 obtained after splitting off the leaving group -R according to DE 198 18 964 A1 initially occur as highly contaminated products which can only be converted into a pure product by very complex isolation and workup processes Form can be brought. This is mainly due to the unreacted preliminary stage contained in the product as the main impurity, i.e. the proportion in which -R is not was split off, as well as attributed to the inorganic components contained. The crude products are isolated for R = methyl by stirring the reaction solution with a sodium hydrogen carbonate solution, the product separating out through gradual neutralization. For R = acetyl, the basic reaction solution is neutralized with an acid, which separates the crude product. For the purification of the raw products up to a quality required for pharmaceutical active substances, technically complex repeated recrystallizations from large solvent volumes combined with a considerable need for reactor volumes, which leads to considerable losses in yield and thus a low space-time yield, are required.

It is therefore an object of the invention to provide a simple process for the preparation of hydroxyindol-3-ylglyoxylamides of the formula 1, especially AWD 12-281, in a particularly pure form which is required for pharmaceutical use.

Description of the invention

The process according to the invention relates to the preparation of hydroxyindol-3-ylglyoxylamides of the formula 1

wherein

R ^{1 is} -C _T -C _ß -alkyl, straight-chain or branched-chain, saturated or partially unsaturated, is optionally mono- or polysubstituted with mono-, bi- or tricyclic saturated or mono- or polyunsaturated carbocycles with 3-14 ring members or mono-, bi- or tricyclic saturated or mono- or polyunsaturated heterocycles with 5-1 5 ring members and 1-6 heteroatoms, which are preferably N, O and S are, the carbocyclic and heterocyclic substituents in turn, if appropriate, one or more times with -OH, -SH, -NH ₂ , -NHC _r C ₆ -alkyl, -N (C _r C ₆ -alkyl) ₂ , -NHC ₆ -C ₁₄ aryl, -N (C ₆ -C ₁₄ aryl) ₂ , -N (C ₁ -C ₆ alkyl) (C ₆ -C _u aryl), -NO ₂ , -CN, -F, -Cl, -Br, -I, -OC _r C ₆ alkyl, -OC ₆ -C ₁₄ aryl, -C _r C ₆ alkyl, -C ₆ -C ₁₄ aryl or / and -COOH may be substituted, each C, -C ₆ alkyl radical on the carbocyclic and heterocyclic substituents in turn can be substituted one or more times with -F, -Cl, -Br, -I, -OH or / and C ₆ -C ₁₄ aryl, and wherein each C ₆ -C ₁₄ aryl radical on the carbocyclic and heterocyclic substituents in turn one or more times with -F, -Cl, -Br, -I, -OH or / and C _r C ₆ alkyl may be substituted,

R ² , R ³ can be hydrogen or -OH, at least one of the two substituents being -OH;

R ^{4 represents} a mono- or polycyclic aromatic carbocycle with 6-14 ring members or a mono- or polycyclic herterocycle with 5-1 5 ring members, the heteroatoms being selected from N, O and S, optionally substituted one or more times with -F, -Cl, - Br, -I, -OH, -SH, -NH _{2 /} - NH (C _r C ₆ alkyl), -N (CC ₆ alkyl) ₂ , -NH (C ₆ -C ₁₄ aryl), -N (C ₆ -C ₁₄ aryl) ₂ , -N (C _r C ₆ alkyl) (C ₆ -C ₁₄ aryl), -NO ₂ , -CN, -OC _r C ₆ alkyl , -OC ₆ -C ₁₄ -aryl, -C _r C ₆ -alkyl, -C ₆ -C ₁₄ -aryl or / and -COOH, where each CC ₆ -alkyl radical in turn contains one or more with -F, -Cl, - Br, - I, -OH or / and -C ₆ -C ₁₄ -aryl can be substituted and each C ₆ -C ₁₄ -aryl group in turn one or more times with -F, -Cl, -Br, -I, - OH or / and CC ₆ alkyl may be substituted. The process is characterized in that 5-benzyloxyindole, 6-benzyloxyindole or 5, 6-dibenzyloxyindole are used as starting materials.

R ¹ is preferably an optionally substituted CC ₃ alkyl radical, such as n-propyl, isopropyl, cyclopentylmethyl or a benzyl radical, which in turn is substituted one or more times by halogen, for example -F, -OC | -C ₆ alkyl or -0- CC ₆ -haloalkyl, for example -OCH ₃ or OCF ₃ , or / and -CC ₆ -alkyl or C _r C ₆ -haloalkyl, for example - CH ₃ or -CF _3, may be substituted.

R ⁴ preferably represents mono- or bicyclic aromatic carbocycles or heterocycles, in particular N-heterocycles. R ⁴ particularly preferably represents phenyl or pyridyl, in particular 4-pyridyl.

It is further preferred that R ⁴ is substituted one or more times with -F, -Cl, -Br or / and I.

Most preferred is the compound AWD12-281 according to formula 2.

The method according to the invention preferably comprises the steps:

(a) Reacting the starting material 1_a according to scheme 1, in which R ² and R ^{3 are} hydrogen or an OH protected by benzyl, where at least one of the two substituents must be a -OH protected by benzyl, with a compound R ¹ -X, in which R ^{1 is} as defined in claim 1 and

X means halogen, to a compound J_b according to the scheme

1 ;

(b) reacting compound J_b with a compound (COX) ₂ , in which X is halogen, to give a compound 1_c according to scheme 1;

(c) reacting compound 1_c with a compound selected from NH ₃ , H ₂ NR and HNR ₂ , wherein each R is independently any organic radical, for example as defined for R ¹ above, preferably with a compound H ₂ NR, where R is as defined for R ⁴ above, to a compound 1_d according to scheme 1 and (d) reacting compound 1 d to the target compound 1, comprising the elimination of benzyl at R ² and / or R ³ and, if appropriate (if this has not yet been done in step (c)), the introduction of the group R ⁴ .

An advantage of the process according to the invention is that the various intermediates according to Scheme 1 with R = benzyl, in contrast to the previously preferred compounds with R = methyl or acetyl, can be isolated in a technologically simple manner and at the same time are obtained in a purity, the purification steps for intermediates do not require.

Furthermore, the end products, namely the hydroxyindol-3-ylglyoxylic acid amides of the formula 1, can also be used in a novel manner, i.e. can be isolated from the reaction mixture in a very pure form with significantly less time, equipment and material expenditure and thus very inexpensively.

For example, only small amounts of suitable solvents are required to prepare solutions from which the hydroxyindol-3-ylglyoxylamides of the formula 1 can be precipitated in a very pure form with acids. According to the prior art, however, very large volumes of solvent, for. B. 75 times the volume with heating, required for the product AWD 1 2-281 and addition of bases.

However, the isolation can also be carried out by adding small amounts of suitable solvents to a solution of hydroxyindol-3-ylglyoxylic acid amides of the formula 1, heating and in the Heat or after cooling, the products are separated in a very pure form.

. C ₄ alcohols, especially ethanol, alcohol mixtures or alcohol mixtures with water - as a solvent for the inventive insulation to lower alcohols such as C, are suitable.

Volumes of up to 15 times the volume, based on the isolated product, are preferably regarded as small volumes of suitable solvents. When using pure alcohols, volumes up to 5 times the volume, based on the isolated product, are sufficient.

Suitable bases for the solution of the hydroxyindol-3-ylglyoxylic acid amides of the formula 1 are suitable bases for the formation of solutions, such as sodium hydroxide solution or potassium hydroxide solution.

Suitable acids for the precipitation of the hydroxyindol-3-ylglyoxylamides of formula 1 are mineral acids such as hydrochloric acid or inexpensive organic acids such as acetic acid.

Both methods of isolation, i.e. Dissolving the hydroxyindol-3-ylglyoxylic acid amides of the formula 1 with the addition of bases in small volumes of suitable solvents with subsequent precipitation and heating in small volumes of suitable solvents, separation in the heat or cooling and separation, repeated or used in combination, as described below is described as an example.

Both variants of the production of hydroxyindol-3-ylglyoxylic acid amides in a particularly pure form are suitable for both laboratory, semi-industrial and technical scales. The processes according to the invention are extraordinarily well suited for producing AWD 12-281 in a particularly pure form.

The invention further relates to compounds of the general formulas 1b, 1_c and ld as shown in the above scheme and their use as intermediates in the synthesis of compounds of the formula 1.

embodiments

The stages of the production and insulation process according to the invention for the production of AWD 12-281 (2) are described in a particularly pure form by way of example:

Step 1: 5-benzyloxy-1 - (4-fluorobenzyl) indole

35.6 g of 5-benzyloxyindole, 94% (0.15 mol)

33.6 g KOH cookies, ground (0.6 mol)

26.0 g 4-fluorobenzyl chloride (0.18 mol) 300 ml DMF

1.5 ml of water

The KOH cookies are added to the mixture of DMF and water and the whole thing is stirred intensively for 5 minutes. After adding the 5-benzyloxyindole, the mixture is stirred for a further 45 minutes at room temperature. Then 4-fluorobenzyl chloride is added dropwise with stirring at an internal temperature of 10-20 ° C. Then that will The mixture was stirred for a further 90 minutes at room temperature. The mixture is cooled to 10 ° C. and 300 ml of water are added. It is cooled so that the internal temperature does not exceed 20 ° C. The whole is stirred for 2 hours, then the precipitate is suctioned off, washed with water and dried at 30 ° C. first in circulating air and then in a vacuum. The product is very pure, so that no additional cleaning operation is required.

Yield: 47.2 g (95% of theory) FP = 77-78 ° C, colorless crystals

Step 2: 5-benzyloxy-1 - (4-fluorobenzyl) indol-3-ylglyoxylic acid chloride

23.86 g 5-benzyloxy-1 - (4-fluorobenzyl) indole (0.072 mol) 9.90 g (7.2 ml) oxalyl chloride (0.078 mol) 300 ml tetrahydrofuran (dry)

A solution of 5-benzyloxy-1- (4-fluorobenzyl) indole in 200 ml THF is cooled to 0 ° C. under an N ₂ atmosphere. A solution of the oxalyl chloride in 100 ml of THF is added dropwise with stirring and further cooling in such a way that the internal temperature does not exceed 10 ° C. The reaction mixture is then refluxed for 2 hours. The solvent is distilled off as completely as possible in vacuo at a bath temperature of 50-60 ° C. The crude product remains as a residue and crystallizes on cooling. It is used in the next reaction stage without further work-up.

Step 3: N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1 - (4-fluorobenzyl) indole-3-yl] glyoxylic acid amide

30.35 g of 5-benzyloxy-1 - (4-fluorobenzyl) indol-3-yl-glyoxylic acid chloride (0.072 mol)

1 1.7 g of 4-amino-3,5-dichloropyridine (0.072 mol) 6.0 g of sodium hydride (60% in paraffin) (0.15 mol) 400 ml of tetrahydrofuran (dry)

The sodium hydride is introduced into 80 ml of THF with stirring. Then a solution of 4-amino-3,5-dichloropyridine in 1 20 ml of THF is added dropwise. After the mixture was stirred for a further 1 hour at room temperature, the mixture was cooled to an internal temperature of -5 to 0 ° C. A solution of the 5-benzyloxy-1 - (4-fluorobenzyl) indol-3-yl-glyoxylic acid chloride (crude product) obtained in the second stage in 200 ml of THF is added dropwise with stirring. The reaction mixture is then refluxed for 3 hours. The solvent is distilled off in vacuo. The residue is stirred with a mixture of 500 ml of water and 500 ml of ethyl acetate at 50 ° C. The phases are separated and the aqueous phase is washed with 100 ml of ethyl acetate. The combined organic phases are washed with 200 ml of water and then the solvent in vacuo to a residual volume of distilled off about 200 ml. The product crystallizes out of the solution on cooling. It is filtered off, washed with 1 5 ml of ethyl acetate and dried at 60 ° C. The filtrate is concentrated to a residual volume of 50 ml in vacuo. Upon cooling, further product crystallizes out, which is washed and dried analogously.

Yield: 29.4 g (74% of theory, calculated for 2nd and 3rd stages) FP = 1 55-1 58 ° C, yellow crystals

Step 4: N- (3,5-dichloropyrid-4-yl) - [1 - (4-fluorobenzyl) -5-hydroxy-indol-3-yl] glyoxylic acid amide (AWD 1 2-281) ( Formula 2)

Option A):

48 g of N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1 - (4-fluorobenzyl) indol-3-yl] glyoxylic acid amide (0.0875 mol) 41.7 g of boron tribromide (0.166 mol)

530 ml of toluene

360 ml of water

50 ml sodium hydroxide solution

720 ml ethanol 57 ml acetic acid

48 g of N- (3,5-dichloropyrid-4-yl) - [1 - (4-fluorobenzyl) -5-benzyloxy-indol-3-yl] - glyoxylic acid amide are heated to 60 to 70 ° C in 480 ml of toluene, 41.7 g of boron tribromide in 50 ml of toluene are added within one hour and the mixture is heated at 60 to 70 ° C for 3 hours. The mixture is cooled to about 20 ° C., 360 ml of water are added and 50 ml of sodium hydroxide solution are added dropwise with cooling until the solid has dissolved. The organic phase is separated off, the aqueous phase is extracted again with 100 ml of toluene and 720 ml of ethanol and 3.6 g of activated carbon are added to the aqueous phase. It is filtered and the product is precipitated with 57 ml of acetic acid. It is suctioned off, washed with water and with ethanol and dried. The yield is 34.1 g, corresponding to 85% of theory. Th.

Variant b):

40 g of N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1- (4-fluorobenzyl) indol-3-yl] glyoxylic acid amide (0.0873 mol)

36.3 g boron tribromide (0.145 mol)

480 ml of toluene

330 ml of water

80 g potassium carbonate

40 g of N- (3,5-dichloropyrid-4-yl) - (1- (4-fluorobenzyl) -5-benzyloxy-indol-3-yl (-glyoxylic acid amide) are in 400 ml of toluene at 70 to 80 ° C. heated, 36.9 g of boron tribromide in 80 ml of toluene are added during the heating and the mixture is heated for a further 3 hours at 75 to 80 ° C. It is cooled to about 20 ° C. and a solution of 330 ml of water and 80 ml of potassium carbonate The product is filtered off with suction, washed with water and ethanol, the moist product is suspended in 400 ml of ethanol and dissolved with the addition of 20 ml of 5N sodium hydroxide solution, and the product is filtered off and precipitated with 10 ml of hydrochloric acid with water and then with ethanol and dries.

The yield is 30.0 g, corresponding to 90% of theory. th Variant c)

3.60 kg N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1 - (4-fluorobenzyl) indol-3-yl] glyoxylic acid amide (6.56 mol)

3.30 kg boron tribromide (13, 17 mol)

42 l toluene

30 l water

4.4 kg of potassium carbonate

24 l ethanol

3.60 kg of N- (3,5-dichloropyrid-4-yl) - [1 - (4-fluorobenzyl) -5-benzyloxy-indol-3-yl] glyoxylic acid amide are in 36 l of toluene at 75 to 80 ° C. heated, 3.3 kg of boron tribromide in 6 l of toluene are added during the heating and the mixture is heated at 75 to 80 ° C for 3 hours. It is cooled to about 20 ° C. and a solution of 30 l of water and 4.4 kg of potassium carbonate is added. It is suctioned off, washed with 9 l of water and 3 l of ethanol. The moist product is refluxed in 15 l of ethanol for 30 min. It is cooled, suctioned, washed with 6 l of ethanol and dried. The yield is 2.85 kg, corresponding to 95% of theory. Th.

Using either of these methods results in AWD 12-281 in high purity. The particularly pure form of the AWD 12-281 produced by the process according to the invention is characterized in that the content is greater than 98% and the total of all impurities is always not more than 0.5%. The content of the known main impurity N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1 ~ (4-fluorobenzyl) indol-3-yl] -glyoxy acid amide is not more than 0 .2% and inorganic constituents have been removed to such an extent that, according to the sulfate ash determination, they are less than 0.1%. Numerous further compounds of formula 1 can be prepared in particularly pure form using the exemplary variants indicated, of which the following are exemplified:

Claims

Expectations

Process for the preparation of hydroxyindol-3-ylglyoxylic acid amides of the formula 1

1 where

R ^{1 is} -CC ₆ -alkyl, straight-chain or branched-chain, saturated or partially unsaturated, is optionally mono- or polysubstituted with mono-, bi- or tricyclic saturated or mono- or poly-unsaturated carbocycles with 3-14 ring members or mono- , Bi- or tricyclic saturated or mono- or polyunsaturated heterocycles with 5-1 5 ring members and 1-6 heteroatoms, which are preferably N, O and S, the carbocyclic and heterocyclic substituents in turn, if appropriate, one or more times with -OH , -SH, -NH ₂ , -NHC _r C ₆ alkyl, -N (C _r C ₆ alkyl) ₂ , -NHC ₆ -C ₁₄ aryl, -N (C ₆ -C ₁₄ aryl) ₂ , -N (C _r C ₆ alkyl) (C ₆ -C ₁₄ aryl), -NO ₂ , -CN, -F, -Cl, -Br, -I, -OC _r C ₆ alkyl, -OC ₆ - C ₁₄ - Aryl, -C, -C ₆ -alkyl, -C ₆ -C ₁₄ -aryl or / and -COOH can be substituted, where each C, -C ₆ -alkyl radical on the carbocyclic and heterocyclic substituents is in turn one or more times with - F, -Cl, -Br, -I, -OH or / and C ₆ -C ₁₄ aryl substitui ert, and where each C ₆ -C ₁₄ aryl radical on the carbocyclic and heterocyclic substituents may in turn be substituted one or more times with -F, -Cl, -Br, -I, -OH or / and CC ₆ -alkyl . R ² , R ³ can be hydrogen or -OH, at least one of the two substituents being -OH;

R ^{4 is} a mono- or polycyclic aromatic carbocycle with 6-14 ring members or a mono- or polycyclic

Herterocycle with 5-15 ring members, the heteroatoms being selected from N, O and S, optionally substituted one or more times with -F, -Cl, - Br, -I, -OH, -SH, - NH ₂ , -NH (C _r C ₆ alkyl), -N (C _r C ₆ alkyl) ₂ , -NH (C ₆ -C ₁₄ aryl), -N (C ₆ -C ₁₄ aryl) ₂ , -N (C _r C ₆ alkyl), (C ₆ -C ₁₄ aryl), -NO ₂ , -CN, -OC _r C ₆ alkyl, -O-

C ₆ -C ₁₄ aryl, -C _r C ₆ alkyl, -C ₆ -C ₁₄ aryl or / and -COOH, with each C., - C ₆ alkyl radical in turn one or more times with -F, - Cl, - Br, -I, -OH or / and -C ₆ -C ₁₄ aryl can be substituted and each C ₆ -C ₁₄ aryl group in turn one or more times with -F, -Cl, -Br, -I , -OH or / and CC ₆ -alkyl may be substituted, characterized in that 5-benzyloxyindole, 6 benzyloxyindole or 5, 6-dibenzyloxyindole is used as the starting material.

2. The method according to claim 1 for the preparation of N- (3,5-dichloropyrid-4-yl) - [1 - (4-fluorobenzyl) -5-hydroxy-indol-3-yl] - glyoxylic acid amide (AWD 12- 281).

3. The method according to claim 1 or 2, characterized in that it comprises the steps:

(a) reacting the starting material 1_a according to scheme 1, wherein

R ² and R ^{3 are} hydrogen or an OH protected by benzyl, at least one of the two substituents being an -OH protected by benzyl, with one

Compound R ^ X, wherein R ^{1 is} as defined in claim 1 and X means halogen, to a compound Tb according to the scheme

1 ;

(b) reacting the compound Vo with a compound {COX) ₂ , in which X is halogen, to one compound each. according to scheme 1;

(c) reacting compound 1_c with a compound selected from NH ₃ , HNR and HNR ₂ , wherein R is any organic residue, to a compound id according to scheme 1 and (d) converting compound id to the target compound 1, comprising the cleavage from benzyl to R ² and / or R ³ .

4. The method according to claim 3, characterized in that 1-substituted 5-benzyloxy, 6-benzyloxy or

5,6-Dibenzyloxyindoles of the formula Jb can be used as intermediates in step (a) without intermediate purification in the next step (b) of the process.

5. The method according to claim 4, characterized in that 5-benzyloxy-1- (4-fluorobenzyl) indole, the intermediate of step (a) of the synthesis of AWD 12-281 without any intermediate purification in the next step (b) of Procedure is used.

6. The method according to any one of claims 3 to 5, characterized in that 1 -substituted 5-benzyloxy, 6-benzyloxy or 5,6-dibenzyloxyindol-3-ylglyoxylic acid chlorides of the formula lc as

Intermediates of stage (b) are used in the next stage (c) without intermediate purification.

7. The method according to claim 6, characterized in that 5-benzyloxy-1 - (4-fluorobenzyl) indol-3-ylglyoxylic acid chloride, the intermediate of step (b) of the synthesis of AWD 12-281, without intermediate purification in the next step (c ) of the procedure is used.

8. The method according to any one of claims 3 to 7, characterized in that 1-substituted 5-benzyloxy, 6-benzyloxy or

5,6-Dibenzyloxyindol-3-ylglyoxylic acid amides of the formula Id of step (c) can be used in the next step (d) of the process without intermediate purification.

9. The method according to claim 8, characterized in that N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1 - (4-fluorobenzyl) - indol-3-yl] glyoxylic acid amide, the Intermediate product of stage (c) of the synthesis of AWD 1 2-281 is used in the next stage (d) of the process without intermediate purification.

10. The method according to any one of claims 3 to 9, characterized in that for cleaning the reaction solution of the crude product stage (d) an alkaline pH is set, in which the solution of

Product is worked up by conventional treatments such as filtration or filtration in the presence of filter aids.

1 1. A method according to claim 10, characterized in that a pH> 9.5 is set to purify the reaction solution.

12. The method according to claim 1 1, characterized in that a pH of> 9.5 is set to purify the reaction solution of AWD 12-281.

13. The method according to any one of claims 10 to 12, characterized in that after the purification of the reaction solution of step (d), the pure hydroxyindol-3-ylglyoxylic acid amides of the formula 1_ by neutralization using organic or inorganic acids up to the pH range from 8 to 6 can be canceled.

14. The method according to claim 13, characterized in that for neutralization and precipitation of the pure

Hydroxyindol-3-ylglyoxylsäureamide hydrochloric acid is used.

15. The method according to claim 14, characterized in that the reaction solution of step (d) of the synthesis of AWD

12-281 after cleaning this solution at alkaline pH by adding hydrochloric acid to pH 8 to 6, causing the pure product to precipitate.

1 6. The method according to any one of claims 3-9, characterized in that crude products of step (d) of the method are dissolved in an alcohol with the addition of an alkali and this solution is worked up by conventional treatments such as filtration or filtration in the presence of filter aids becomes.

17. The method according to claim 16, characterized in that ethanol and sodium hydroxide solution are used.

18. The method according to claim 17, characterized in that ethanol and sodium hydroxide solution are used for working up the crude product of AWD 12-281.

19. The method according to any one of claims 16 to 18, characterized in that the pure hydroxyindol-3-ylglyoxylic acid amides are precipitated after working up the raw products by adding an organic or inorganic acid to a pH range of 8 to 6.

20. The method according to claim 19, characterized in that the pure hydroxyindol-3-ylglyoxylic acid amides are precipitated after working up the raw products by adding hydrochloric acid to a pH range of 8 to 6.

21. A method according to claim 20, characterized in that pure AWD 1 2-281 is precipitated after working up the crude product by adding hydrochloric acid up to the pH range from 8 to 6.

22. The method according to any one of claims 1 to 21, characterized in that AWD 12-281 is produced with a content of more than 98%.

23. The method according to any one of claims 1 to 22, characterized in that the sum of all related impurities in AWD 12-281 is not more than 0.5%.

24. The method according to any one of claims 1 to 23, characterized in that the content of the main impurity N- (3,5-dichloropyrid-4-yl) - [5-benzyloxy-1- (4-fluorobenzyl) indole -3-yl] - glyoxylic acid amide AWD 12-281 is not more than 0.2%.

25. Compounds of general formulas 1_b, 1_c and id according to scheme 1, wherein R ⁴ and R ^{5 are} as defined in claim 1 and R ² , R ³ and R are as defined in claim 3.

26. Use of compounds according to claim 25 as intermediates in the synthesis of compounds of general formula 1 as defined in claim 1.