DE10248277A1 - Preparation of optically active 1-hydroxy-2-alkylaminoethane compounds, useful as bronchodilators for treating e.g. asthma, by reacting an amine with reactive 2-substituted ethanol, also new intermediates - Google Patents

Abstract

Methods for preparing optically active 1-hydroxy-2-alkylaminoethane compounds (I) and their salts, are new. Methods for preparing optically active 1-hydroxy-2-alkylaminoethane compounds of formula (I) and their salts comprise: (a) reacting R3NH2 with reactive intermediate (II); or (b) reacting the corresponding optically active primary amine (IV; R3 replaced by hydrogen) with R3-X. R1 = optionally substituted (hetero)aromatic group; R2 = hydrogen or optionally substituted alkyl; R3 = optionally substituted alkyl, optionally containing one or more oxygen atoms or NH groups; and X = conventional leaving group. Independent claims are also included for: (1) method for preparing optically active compounds (VIII) by asymmetric reduction of ketones (VII) in presence of an alcohol dehydrogenase (ADH) and NADH; and (2) optically active (VIII) in which the R-configuration at the carbon bonded to hydroxy is present in enantiomeric excess of over 50, and their salts. R1COCHR2R9 (VII) R1.CH(OH).CHR2R9 (VIII) R9 = X or amino.

Description

The invention relates to a new one Process for the production of optically active compounds, in particular optically active alcohols, especially enantiomerically pure alcohols, The compounds mentioned are pharmaceutically active and represent so-called β-agonists The invention further relates to a method for manufacturing of optically active intermediates as well as new optically active ones Intermediates.

(1-(4-Amino-3,5-dichlor-phenyl)-2-tert.-butylamino-ethanol). Das Hydrochlorid des Racemats ist im Handel als Spiropent^® bzw. Ventipulmin^® erhältlich und wirksam in der Behandlung von Asthma bronchiale, astmoider Bronchitis, chronischer Bronchitis und Ephysembronchitis.β-2 sympathomimetics are the most effective means of expanding the bronchi (bronchodilation). They resemble the body's own messenger substances of the nervous system and have the same effect on the bronchi as adrenaline: the airways are expanded. The β-agonists are a group of beta-2 sympathomimetics that contain a large number of chiral active substances and which are currently only available as racemates or enantiomerically pure in amounts of a few milligrams. Enantiomerically pure compounds of this type are obtained, inter alia, using complex chromatographic methods starting from the costly racemate produced with environmentally harmful catalysts (Vela J, Yanes EG, Stalcup AM. Fresenius J. Anal, Chem. 2001 Feb; 369 (3-4): 212- 9). The column chromatographic method for separating the racemate was first carried out in 2001 using the example of clenbuterol, salbutamol and tulbuterol. However, only about 2 mg of the enantiomerically pure active ingredient are obtained. Clenbuterol (INN) is one of the most important representatives of the β-agonists;

(1- (4-Amino-3,5-dichloro-phenyl) -2-tert.-butylamino-ethanol). Racemate hydrochloride is commercially available as Spiropent ^® or Ventipulmin ^® and is effective in the treatment of bronchial asthma, astmoid bronchitis, chronic bronchitis and ephysembronchitis.

mit Natriumborhydrid zum racemischen Alkohol reduziert (dto. AT-A-280997 ). Weitere Methoden zur Herstellung von Racematen dieser Phenylaminoethanole sind beschrieben in der US-A-3535712 .The synthesis of the racemate of clenbuterol is the first in the DE-A-1793416 has been described, the starting ketone

reduced with sodium borohydride to racemic alcohol (dto. AT-A-280 997 ). Further methods for the preparation of racemates of these phenylaminoethanols are described in US-A-3535712 ,

The final introduction of the substituents on the aromatic ring after prior protection of the aminoethanol group has also been described (see .: Keck, J. et al .; Arzneimittel.-Forsch. (ARZNAD) 22, 861 (1972)), DE 1793416 . BE 704213 and US 3536712 );

The use of racemates in the therapeutic treatment of humans or animals is often associated with disadvantages.For example, it is known that, in contrast to the (R) -enantiomer, the (S) -enantiomer does not exist for the phenylethanolamines which act as β-2-sympathomimetics or has little bronchodilator effect ( DE-A-4209989 ) and the (S) -enantiomer, for example in the case of albuterol, is the main carrier of undesirable side effects ( WO 91/09596 ).

In the case of α-phthalimidoglutarimide (Thalidomide) has the (S) enantiomer due to its teratogenic side effect, even sad fame acquired ("Contergan", see e.g., Römpp, chemistry lexicon, 10, edition keyword "Thalidomide").

ist beschrieben in der DE-A-2128258 . Die Synthese geht aus von racemischem

das zunächst durch Umsetzung mit optisch aktiven Weinsäurederivaten in die optischen Antipoden gespalten wird und anschließend reduziert und katalytisch entbenzyliert wird, Die Synthese erfordert eine Vielzahl von Schritten, die dreimalige Umkristallisation sowie den Einsatz optisch aktiver Hilfsreagentien. Schließlich fällt das unerwünschte (S)-Enantiomer zwangsläufig als Nebenprodukt an.The Production of the R - (-) - Enantiomer of Albuterol (Salbutamol)

is described in the DE-A-2128258 , The synthesis is based on racemic

which is first split into the optical antipodes by reaction with optically active tartaric acid derivatives and then reduced and catalytically debenzylated. The synthesis requires a large number of steps, the recrystallization three times and the use of optically active auxiliary reagents. Finally, the undesired (S) enantiomer is inevitably a by-product.

Similarly, the optical cleavage of the cimaterol takes place with the help of optically active tartaric acid derivatives ( EP-A-0455155 ).

The DE-A-2345442 also describes the preparation of optically active β-agonists by fractional crystallization of a mixture of diasteromeric salts with optically active acids or by column chromatography on optically active carrier materials.

All procedures based on the split of a racemate, is common that the undesired enantiomer is a by-product of the cleavage.

KR-B-ß306944 describes the production of racemic clenbuterol.

Vela J, Yanes E.G., Stalcup A.M., Fresenius J. Anal. Chem. 2001 Feb .; 369 (3-4): 21 2-9 describe the Isolation and quantitative determination of clenbuterol, salbutamol and tulobuterol enantiomers Capillary electrophoresis. The process is unsuitable for larger scales.

Kim K.H., Kim H.J., Jeun E.Y., Seo S.H., Hong S.P., Kang J.S., Youm J.R. and Lee S.C., Arch. Pharm. Res. 2001 Aug; 24 (4); 281-5 also describe chiral separation of β2 agonists by capillary electrophoresis using hydroxypropyl-alphacyclodextrin as a chiral selector.

Abou-Basha L.I. and Aboul-Enein H.Y., Biomed. Chromatogr. 1996 March-April; 10 (2): 69-72 describe the direct enantioselective separation of Clenbuterol by chiral HPLC in biological fluids.

Another synthetic approach to optically active ethanolamines is described in US 60691 76 There, a conversion of optically active mandelic acid derivatives to amides and the subsequent reduction to the ethanol amines are described. However, this synthetic route also requires a reduction step in the presence of certain reducing agents.

It is common to many manufacturers active pharmaceutical ingredients the default, if available chiral centers in the active substance, the optical antipodes only individually to develop to market maturity in the form of enantiomerically pure compounds. In particular, there were as β-2 sympathomimetics effective ethanolamines the desire for a simple and universal applicable access to the preferred enantiomerically pure compounds, especially the (R) -enantiomers. Access should be simultaneous a high yield of the desired Enantiomers result in the use of expensive chiral chromatography columns and avoid the use of expensive reducing agents and not for education greater Amounts of unwanted By-products.

The inventors of the present invention succeeded surprisingly using this task through a new simple synthesis route one optically active obtained by an asymmetric synthesis To solve intermediate product. The desired optically active compounds serving as active pharmaceutical ingredients can be from the optically active intermediates by a produce nucleophilic substitution reaction. The inventors succeeded it continues to manufacture new optically active intermediates the β-agonists as well as a To provide processes for producing the optically active intermediates, The optically active intermediates can be used to produce enantiomerically pure β-agonists, such as in particular (R) -Clenbuterol in high yields without the use expensive chiral chromatography columns or expensive reducing agents and without the formation of great ones Amounts of unwanted Produce by-products, The enantiomerically pure forms of β-agonists using the example of (R) -Clenbuterol show an increase in the effect of enlargement of the bronchi or new properties regarding their effects. In which Processes of the invention do not come with heavy metal catalysts chemicals that pollute the environment. An extensive one Use of organic solvents is not necessary.

worin
R¹ eine aromatische oder heteroaromatische Gruppe ist, die gegebenenfalls substituiert sein kann,
R² aus der Gruppe ausgewählt wird, die aus Wasserstoff und gegebenenfalls substituiertem Alkyl besteht, und
R³ eine gegebenenfalls substituierte Alkylgruppe ist, die gegebenenfalls eine oder mehrere Gruppen ausgewählt aus -O- und -NH- enthalten kann,
oder Salzen davon bereit, dassThe present invention thus provides a process for the preparation of optically active compounds of the formula (1)

wherein
R ^{1 is} an aromatic or heteroaromatic group which can be optionally substituted,
R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and
R ^{3 is} an optionally substituted alkyl group which may optionally contain one or more groups selected from -O- and -NH-,
or salts ready for that

• (a) the reaction of an optically active compound of the formula (II)
  
  wherein R ¹ and R ^{2 are} as defined above and X is a conventional leaving group with a compound of the formula (III)
  
  wherein R ^{3 is} as defined above, or
• (b) the reaction of an optically active compound of the formula (IV)
  
  wherein R ¹ and R ^{2 are} as defined above, with a compound of formula (V) R 3 -X (V) wherein X and R ^{3 are} as defined above.

mit R = Menge der (R)-Form und S = Menge der (S)-Form, d.h. ee = 0 für das Racemat und ee = 1 00 % für die reine (R)- oder (S)-Form. Die nach dem Verfahren der Erfindung erhaltenen optisch aktiven Verbindungen weisen somit einen ee von mehr als 0 auf, Im Allgemeinen betragen die Enantiomerenüberschüsse der nach dem Verfahren der Erfindung hergestellten optisch aktiven Verbindungen mehr als 50 %, bevorzugt mehr als 80 %, bevorzugter mehr als 90 noch bevorzugter mehr als 95 % und in den meisten Fällen mehr als 98 % bis 100%. Bevorzugt weisen die erfindungsgemäß hergestellten Verbindungen einen Überschuß, wie zuvor beschrieben, des (R)-Enantiomeren (Konfiguration am markierten Kohlenstoffatom) auf.Since the preparation of the compounds according to the invention in both variants (a) and (b) starts from optically active compounds of the formulas (II) and (IV) and the substituents on the labeled carbon atom during the nucleophilic substitution reaction are essentially not subject to any change in configuration, with the process of the invention provides optically active compounds of the formula (I). This means that non-racemic mixtures of the compounds of the formula (I), in particular also enantiomerically pure compounds of the formula (I) are provided, the solutions of which rotate the plane of polarization of transmitted linearly polarized light. Since, as described below, the synthesis of the optically active intermediates of formulas (II) and (IV) is almost 100% stereoselective, the alcohols with high ee values are obtained (ee = enantiomeric excess). The enantiomeric excess (ee) is defined as the absolute amount of the percentages of both enantiomers in the product mixture:

with R = amount of the (R) shape and S = amount of the (S) shape, ie ee = 0 for the racemate and ee = 1 00% for the pure (R) or (S) shape. The optically active compounds obtained by the process of the invention thus have an ee of more than 0. In general, the enantiomeric excesses of the optically active compounds prepared by the process of the invention are more than 50%, preferably more than 80%, more preferably more than 90 more preferably more than 95% and in most cases more than 98% to 100%. The compounds prepared according to the invention preferably have an excess, as described above, of the (R) -enantiomer (configuration on the labeled carbon atom).

R ¹ is an aromatic or heteroaromatic group which may optionally be substituted. The aromatic or heteroaromatic group is preferably substituted, particularly preferably with one to three substituents. The aromatic group includes aromatic groups preferably having up to 15 carbon atoms, including the carbon atoms of the substituents. The aromatic group is preferably phenyl, which preferably has 1 to 3 substituents. The heteroaromatic group is preferably a 5- or 6-membered aromatic group with up to 15 carbon atoms, the carbon atoms of the substituents being included, and which has at least one heteroatom, preferably nitrogen. Pyridyl, particularly preferably 2-pyridyl, is preferred:

The substituents of the aromatic and the heteroaromatic groups are preferably selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino such as amino, mono- or dialkylamino, optionally substituted alkyl such as alkyl, haloalkyl, hydroxyalkyl etc. and optionally substituted hydroxy, such as hydroxy, alkoxy. Alkyl in the Definition for R ¹ in the present invention stands for straight-chain or branched-chain alkyl groups with preferably up to 12, more preferably up to 10, particularly preferably up to 6 carbon atoms, such as methyl, ethyl, propyl etc. This also applies to the alkyl moieties in mono- or Dialkylamino, haloalkyl etc.

The aromatic group also closes benzo-fused di- or tricyclic compounds, a or can have several heteroatoms, in particular nitrogen. As well includes the heteroaromatic group condensed di- or tricyclic Ring systems.

R ² is selected from the group consisting of hydrogen and optionally substituted alkyl. In the present invention, alkyl in the definition of R ² stands for straight-chain or branched-chain alkyl groups with preferably up to 1 2, more preferably up to 10, particularly preferably up to 6 carbon atoms, such as methyl, ethyl, propyl etc. R ² is preferably hydrogen or ethyl R ² is particularly preferably hydrogen, R ³ in the present invention represents an optionally substituted alkyl group which may optionally contain one or more groups selected from -O- and -NH-. In the present invention, alkyl in the definition of R ³ stands for straight-chain or branched-chain alkyl groups with preferably up to 1 2, more preferably up to 10, particularly preferably up to 6 carbon atoms. Branched C ₃ -C ₆ alkyl, such as isopropyl, sec-butyl, tert is particularly preferred. Butyl, tert-pentyl. Alkyl can be substituted, with one to three substituents being preferred. If there are substituents, the total number of carbon atoms is preferably up to 24.

The case in which R ² and R ^{3 represent} substituted alkyl groups is also intended to include the case in which R ² and R ³ together form an α, ω-alkanediyl group, such as in particular tetramethylene, so that structures of the following formula result;

worin
A N oder CR⁴ ist, worin
R⁴ aus der Gruppe ausgewählt wird, die aus Wasserstoff und Halogen besteht,
R⁵ aus der Gruppe ausgewählt wird, die aus Wasserstoff, Halogen, Cyano, Hydroxy, gegebenenfalls substituiertem Amino, wie Amino, Mono- oder Dialkylamino, gegebenenfalls substituiertem Alkyl, wie Alkyl, Halogenalkyl, Hydroxyalkyl, und gegebenenfalls substituiertem Hydroxy, wie Alkoxy, besteht, oder
R⁴ und R⁵ gemeinsam einen zweiwertigen, gesättigten oder ungesättigten Kohlenwasserstoffrest mit bis zu vier Kohlenstoffatomen bilden, der durch Oxo substituiert sein kann und der eine Gruppe – NH- aufweisen kann,
R⁶ aus der Gruppe ausgewählt wird, die aus Wasserstoff, gegebenenfalls substituiertem Amino, wie Amino, Mono- oder Dialkylamino, und gegebenenfalls substituiertem Hydroxy, wie Alkoxy, besteht,
R' aus der Gruppe ausgewählt wird, die aus Wasserstoff, Halogen, Cyano, Hydroxy, gegebenenfalls substituiertem Amino, wie Amino, Mono- oder Dialkylamino, gegebenenfalls substituiertem Alkyl, wie Halogenalkyl, Hydrxyalkyl etc., und gegebenenfalls substituiertem Hydroxy, wie Alkoxy, besteht,
B N oder CR⁸ ist, worin
R⁸ aus der Gruppe ausgewählt wird, die aus Wasserstoff und Halogen besteht, oder
R⁷ und R⁸ gemeinsam einen zweiwertigen, gesättigten oder ungesättigten Kohlenwasserstoffrest mit bis zu vier Kohlenstoffatomen bilden, der durch Oxo substituiert sein kann und der eine Gruppe – NH- aufweisen kann,
Alkyl in den obigen Definitionen für R⁵ bis R⁷ steht in der vorliegenden Erfindung für geradkettige oder verzweigtkettige Alkylgruppen mit bevorzugt bis zu 12, bevorzugter bis zu 10 besonders bevorzugt bis zu 6 Kohlenstoffatomen, wie Methyl, Ethyl, Propyl etc. Dies gilt auch für die Alkylanteile in Dialkylamino, Halogenalkyl, Hydroxyalkyl, Alkoxy etc.In a preferred embodiment of the process of the present invention, R ^{1 represents} a group of formula (VI);

wherein
Is AN or CR ⁴ , wherein
R ^{4 is} selected from the group consisting of hydrogen and halogen,
R ^{5 is} selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino, such as amino, mono- or dialkylamino, optionally substituted alkyl, such as alkyl, haloalkyl, hydroxyalkyl, and optionally substituted hydroxy, such as alkoxy , or
R ⁴ and R ⁵ together form a divalent, saturated or unsaturated hydrocarbon radical with up to four carbon atoms, which can be substituted by oxo and which can have a group - NH -,
R ^{6 is} selected from the group consisting of hydrogen, optionally substituted amino, such as amino, mono- or dialkylamino, and optionally substituted hydroxy, such as alkoxy,
R 'is selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino such as amino, mono- or dialkylamino, optionally substituted alkyl such as haloalkyl, hydroxyalkyl etc. and optionally substituted hydroxy such as alkoxy .
Is BN or CR ⁸ , wherein
R ^{8 is} selected from the group consisting of hydrogen and halogen, or
R ⁷ and R ⁸ together form a divalent, saturated or unsaturated hydrocarbon radical with up to four carbon atoms, which can be substituted by oxo and which can have a group - NH -,
Alkyl in the above definitions for R ⁵ to R ⁷ in the present invention stands for straight-chain or branched-chain alkyl groups with preferably up to 12, more preferably up to 10, particularly preferably up to 6 carbon atoms, such as methyl, ethyl, propyl etc. This also applies to the alkyl moieties in dialkylamino, haloalkyl, hydroxyalkyl, alkoxy etc.

In a further preferred embodiment of the method of the invention, A is CR ⁴ and B CR ⁸ , wherein R ⁴ and R ^{8 are} each hydrogen.

In a further preferred embodiment of the process of the invention, in the group of the formula (VI) R ⁵ and R ^{7 are selected} independently of one another from the group consisting of hydrogen, halogen, cyano, hydroxy, hydroxyalkyl, preferably alkyl having one to three hydroxy groups, preferred hydroxy (C1-C6) alkyl, such as hydroxymethyl, hydroxyethyl etc., haloalkyl, preferably alkyl having at least one to three halogen atoms, more preferred mono- to perhalo (C1-C6) alkyl, such as trifluoromethyl etc., dialkylaminocarbonyloxy, preferably di (C1 -C6) alkylaminocarbonyloxy such as dimethylaminocarbonyloxy etc., arylcarbonyloxy, preferably optionally substituted phenylcarbonyloxy, such as 4-methylphenylcarbonyloxy etc., ureido and alkanoylamino, preferably (C1-C6) alkanoylamino, such as formylalkanoylamino, and / or
R ⁵ and R ⁴ and / or R ⁷ and R ⁸ form a divalent radical of the formula

In a further preferred embodiment of the method of the invention, R ^{6 is} selected from the group consisting of hydrogen, amino and hydroxy.

In a further particularly preferred embodiment of the process of the invention process, R ^{2 is} hydrogen.

In a further preferred embodiment of the process of the invention, R ^{3 is} a straight-chain or branched alkyl group which optionally has one or more substituents selected from the group consisting of an aromatic and / or heterocyclic group which may optionally be substituted and hydroxyl, and where the alkyl group may optionally contain one or more groups -O- and / or -NH-. R ³ is particularly preferably a branched alkyl group having three to six carbon atoms, in particular isopropyl and tert-butyl.

As already explained above, the compounds prepared according to the invention are optically active compounds, that is to say that non-racemic mixtures and in particular enantiomerically pure compounds of the formula (I) are provided, the solutions of which rotate the plane of polarization of transmitted linearly polarized light In the case that A is CR ⁴ and B is CR ⁸ , compounds produced according to the invention preferably have the (R) configuration on the labeled carbon atom with an enantiomeric excess (ee) of greater than 0, preferably more than 50, more preferably more than 80%, even more preferably more than 90% most preferably more than 95% and up to> 98% to 100%.

The configuration on the labeled carbon atom is determined according to the rules of Cahn, Ingold and Prelog, first all four ligands of the labeled carbon atom are determined (rule 1), then the ligands are assigned the priorities by looking at the atoms that are directly attached to the marked carbon atom are bound. The higher the atomic number, the higher the priority. With identical atoms, each ligand is followed until a difference is found (Rule 2). Then the molecule is oriented in space so that the group with the lowest priority points away from the viewer (rule 3) and finally the other three groups are followed in order from highest to lowest priority. If the path goes to the right (clockwise), the absolute configuration is (R). If the path goes left, the absolute configuration is (S) (Rule 4). This is shown below for the (R) -clenbuterol preferably produced according to the invention:

In the event that A or B in the group of formula (VI) is N, the configuration is generally reversed so that the labeled carbon atom preferably overlaps the (S) configuration with an enantiomer shot (ee) of more than 80%, In a preferred embodiment of the process of the invention, the process is used to produce (R) -clenbuterol with an enantiomeric excess (ee) of more than 80%, preferably more than 90%, more preferably more than 95% and most preferably more than 98%.

Methods (a) and (b) above for the preparation of the optically active alcohols of the formula (I) are described in in a manner known per se, as for nucleophilic substitution reactions usually carried out. The Implementation is conveniently carried out in one solvent or in an excess of the amine of the formula (III) (variant (a)) or of the compound of the formula (V) (Variant (b)), optionally in the presence of a catalyst. The reaction can take place at room temperature or at elevated temperatures up to 150 ° C carried out become. Working up the reaction mixture and isolation the compound of formula (I) is carried out in the usual way.

According to the invention, they are preferred optically active compounds of formula (I) according to variant (a).

The nucleophilic substitution reaction for the preparation of the optically active compounds of formula (I) proceeds essentially while maintaining the configuration on the asymmetric carbon atom the optically active compounds of formulas (II) and (IV), i.e. the optically active compounds of formula (I) are essentially obtained with the same optical purities as those used optically active compounds of the formulas (II) and (IV).

For the starting compounds of the formulas (II) to (V), with regard to preferred definitions of the substituents R ¹ , R ² and R ³ , reference can be made to the above explanations for the optically active compounds of the formula (I).

X represents a conventional leaving group A conventional leaving group as defined by for X according to the invention is supposed to be conventional leaving groups in nucleophilic substitution reactions a (synonyms are leaving group, nucleofuge group or “leaving group "). Preferred are those with a low steric requirement. The leaving group is preferably selected from halogens, such as fluorine, Chlorine, bromine and iodine, methanesulfonyl, trifluoromethanesulfonyl (triflate), Hydroxy, cyano, alkoxy, alkanoyloxy, such as formlate, acetate, etc. Especially preferably the leaving group X is a halogen atom, most preferred Chlorine or bromine.

Salts of the optically active compounds of the formula (I) prepared in accordance with the invention include, in particular, acid addition salts. In general, suitable acids are inorganic acids such as hydrochloric acid or sulfuric acid, or organic carboxylic acids with one to six carbon atoms, optionally substituted by fluorine, chlorine and / or bromine such as acetic acid, trifluoroacetic acid, trichloroacetic acid or propionic acid, or sulfonic acids with C _1- C ₄ -alkyl radicals or aryl radicals such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid, hydrochloric acid is particularly preferred. Hydrochlorides, sulfates, salts with carboxylic acids such as acetate, etc. are thus most preferred. The salts can be prepared from the neutral compounds in a manner known per se, for example by introducing hydrogen chloride gas into solutions of the neutral compounds in organic solvents.

β-2-sympathomimetic or salts thereof, for example by the process according to the invention for the preparation of the optically active compounds of the formula (I) can be made are listed in the following table:

Is particularly preferred after method according to the invention for the preparation of the optically active compounds of the formula (I) the (R) form of clenbuterol or salts thereof, especially that Hydrochloride made of it.

worin R¹ und R² wie oben definiert sind, und R⁹ X oder -NH₂ ist, worin X wie oben definiert ist.In a preferred embodiment of the process of the invention, the intermediates of the formulas (II) and (IV) or salts thereof are prepared by asymmetrically reducing a compound of the formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{9 is} X or -NH ₂ , wherein X is as defined above.

The asymmetric reduction mentioned chemical reduction, for example with chiral reducing agents lock in, is preferred, however, with regard to the object of the invention the enzymatic reduction of the ketones of the formula (VII). Especially the enzymatic reduction of the ketones of the formula is preferably carried out (VII) in the presence of an alcohol dehydrogenase and NADH to the compounds of Formulas (II) and (IV).

worin
R¹ eine aromatische oder heteroaromatische Gruppe ist, die gegebenenfalls substituiert sein kann,
R² aus der Gruppe ausgewählt wird, die aus Wasserstoff und gegebenenfalls substituiertem Alkyl besteht, und
R⁹ X oder -NH₂ ist, worin X eine konventionelle Abgangsgruppe ist,
oder deren Salze, dass die asymmetrische Reduktion einer Verbindung der Formel (VII)

worin R¹ und R² wie oben definiert sind, und R³ X oder -NH₂ ist, worin X wie oben definiert ist, in Gegenwart einer Alkohol-Dehydrogenase und NADH umfasst.The invention thus also relates to a process for the preparation of optically active compounds of the formula (VIII)

wherein
R ^{1 is} an aromatic or heteroaromatic group which can be optionally substituted,
R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and
R ^{9 is} X or -NH ₂ , where X is a conventional leaving group,
or their salts that the asymmetric reduction of a compound of formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{3 is} X or -NH ₂ , wherein X is as defined above, in the presence of an alcohol dehydrogenase and NADH.

With regard to the preferred meanings of the radicals R ¹ and R ² , reference can be made to the above statements regarding the compounds of the formula (I).

In a particularly preferred embodiment of the method according to the invention for the preparation of the intermediates of the formulas (II) and (IV) or (VIII) these are obtained in the form that the labeled carbon atom in the compounds mentioned the (R) configuration with an enantiomeric excess (ee) more than 50%, more preferably more than 80%, even more preferred more than 90%, more preferably more than 95% and most preferred has more than 98% up to 100% without separation of the enantiomers would be required by conventional optical splitting.

X represents a conventional leaving group as already mentioned above for the compounds of formula (II) has been defined. With regard to the preferred embodiments for X can thus to the above explanations in connection with the compounds of formula (II). The leaving group is therefore preferably selected from halogens, such as fluorine, Chlorine, bromine and iodine, methanesulfonyl, trifluoromethanesulfonyl (triflate), Hydroxy, cyano, alkoxy, alkanoyloxy, such as acetate, etc. Especially preferably the leaving group is a halogen atom, most preferred Chlorine or bromine. X is therefore preferably chlorine or bromine.

Salts of the optically active intermediates of the formula (II) prepared according to the invention, if they contain amino groups, and of the formulas (IV) and (VIII) include, in particular, acid addition salts. In general, inorganic acids such as hydrochloric acid or sulfur are suitable as acids acid, or organic carboxylic acids with 1 to 6 carbon atoms, optionally substituted by fluorine, chlorine and / or bromine, such as, for example, acetic acid, trifluoroacetic acid, trichloroacetic acid or propionic acid, or sulfonic acids with C ₁ -C ₄ -alkyl residues or aryl residues, such as methanesulfonic acid, ethanesulfonic acid, Benzenesulfonic acid or toluenesulfonic acid. Hydrochloric acid is particularly preferred as the hydrochloride.

The enzymatic reduction of the ketones of formula (VII) for the preparation of the intermediates according to the invention of the formulas (II) and (IV) or (VIII) preferably takes place in the presence an alcohol dehydrogenase (ADN) and NADH (nicotinamide adenine dinucleotide, reduced form).

The process according to the invention is particularly preferably carried out with an alcohol dehydrogenase which is selected from alcohol dehydrogenase which originates from Rhodococcus erythropolis and one of these corresponding recombinantly produced alcohol dehydrogenase. The use of such enzymes for reducing ketones is known per se and was in the DE 4209022 described, With regard to the exact production conditions of the enzymes and the reduction conditions can therefore also DE 4209022 to get expelled. However, in the DE 4209022 described substrates only receive alcohols with (S) configuration. It was therefore surprising that the substrates of the formula (VII) used according to the invention practically only form (R) alcohols. It was only for this reason that it was only possible to use the process for the preparation of the intermediates according to the invention and their use in the preparation of the compounds of the formula (I), since their pharmacologically preferred enantiomer, which is the (R) -isomer, relates exclusively to the preparation the (S) alcohols DE 4209022 thus gave no indication of a process for the preparation of (R) -enantiomers.

In a preferred embodiment of the method according to the invention for the preparation of the compounds of the formula (II) and (IV) or (VIII) the reaction takes place in the presence of alcohol dehydrogenase from Rhodococcus erythropolis, which is produced recombinantly.

The manufacturing method according to the invention the compounds of formula (II) and (IV) or (VIII) can advantageously in a continuous process, for example in an enzyme membrane reactor or be performed in a two-phase system, The enantioselective Reduction can be overexpressed with the wild type enzyme and / or recombinantly Enzymes take place. However, extracellular conversion is preferred with a crude cell extract.

The enzymes are useful in the Form of crude cell extracts used by wet grinding of Wet cells of a recombinant strain, such as one E. coli strain or the wild-type strain Rhodococcus erythropolis getting produced. Approx. 3 ml of crude extract can be made from 1 g of moist mass receive. The activity this preparation is approx. 400 U / ml.

The dehydrogenase concentration can can be varied in a very wide range. It depends on of availability and specific activities the dehydrogenases and the type of enzyme preparation and Purity of the enzyme. Enzyme activities of more than 1 m U / mg protein used. The enzyme concentration is preferably at 0.05 to 30 U / ml, particularly preferably at 0.1 to 20 U / ml and very particularly preferably 1 to 10 U / ml. Particularly highlighted be concentrations of 4 to 8 U / ml.

The substrate (ketone) concentration can about wide ranges can be varied. The ketones to be reduced are in the reaction system, preferably in concentrations of 0.1 to 20 mmol / l, in particular from 1 to mmol / l, very particularly preferred from 3 to 7 mmol / l and especially highlighted at about 3.5 mmol / l.

The concentration of the coenzyme NADH is also largely variable. The enzyme is in concentrations of preferably 10 1500 mu mol / ml, particularly preferably from 50 to 500 mu mol / ml and very particularly preferably from 150 to 200 mu mol / ml used.

The manufacturing method according to the invention of the compounds of formula (II) and (IV) or (VIII) can at temperatures from 0 ° to 70 ° C, preferred at 20 to 40 ° C, more preferably be carried out at room temperature (25 ° C) since the enzyme is alcohol Dehydrogenase EC 1.1.1.1, preferably from Rhodococcus erythropolis, advantageously has a high thermal stability, this also has Follow that for a desired one Sales less enzyme needed is, which can save costs. On complex cooling measures can be dispensed with.

The manufacturing method according to the invention the compounds of formula (II) and (IV) or (VIII) is preferred in watery solution or suspension carried out, The addition of the starting ketone of formula (VII) to the reaction system expediently takes place in one solution a polar organic solvent, such as. DMSO, so the reaction is generally in a mixture of water and at least one organic solvent.

The implementation is conveniently under Stir.

The process according to the invention for the preparation of the compounds of the formulas (II) and (IV) or (VIII) can be carried out at a pH of about 6 to 8, preferably 6 to 7, particularly preferably about 6.5, since those involved Enzymes in this pH have good activity and maximum stability. This is advantageous since the starting material of formula (VII) used has a higher stability at this pH, than at higher pH values that normally have to be observed in enzymatic reactions.

To set a suitable one Anyone can use pH an enzymatic reaction of suitable buffers can be used. These are for example: triethanolamine (TEA), tris (hydroxymethyl) aminoethane (TRIS), N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) and 3- (N-morpholino) propanesulfonic acid (MOPS). The concentration ranges for the buffers are preferably between 50 mmol / l and 5 mol / l, preferably up to about 500 mmol / l.

The manufacturing method according to the invention the compounds of formula (II) and (IV) or (VIII) is preferred in the presence of a reduction system or a reducing agent performed for the regeneration of NAD + to NADH, e.g. B. by adding Isopropanol and / or formates and formate dehydrogenase (FDH). NAD + can also be regenerated electrochemically in a known manner. This is particularly advantageous if the process is continuous carried out should be (e.g. with the help of immobilized enzyme).

The reaction mixture particularly preferably additionally contains formate dehydrogenase (FDH) and at least one formate for the regeneration of NAD ⁺ to NADH.

Such as formate dehydrogenase (FDH) used like one from Candida bodinii. As a reducing agent formates are preferred. Formates can, for example, alkali metal or alkaline earth metal formates Alkali metal formates are preferred, particularly sodium formate is preferred, the concentration of the formates in Reaction system is preferably 100 to 200 mM.

The ratio of the amounts of ADN to FDH is conveniently included 1: 2.

The process according to the invention for the preparation of the compounds of the formulas (II) and (IV) or (VIII) can thus be represented as follows:

Working up the reaction mixture takes place in a manner known per se, and the isolation of the enantiomerically pure reaction product is carried out, for example, chromatographically, such as by flash chromatography.

worin
R¹ eine aromatische oder heteroaromatische Gruppe ist, die gegebenenfalls substituiert sein kann,
R² aus der Gruppe ausgewählt wird, die aus Wasserstoff und gegebenenfalls substituiertem Alkyl besteht, und
R³ X oder -NH₂ ist, worin X eine konventionelle Abgangsgruppe ist, und dass markierte Kohlenstoffatom die (R)-Konfiguration mit einem Enantiomerenüberschuss (ee) von mehr als 50 %, bevorzugt mehr als 80 %, bevorzugter mehr als 90 %, noch bevorzugter mehr als 95 und am meisten bevorzugt mehr als 98 bis 100% aufweist.The invention thus also relates to the compounds of the formula (IX) suitable as intermediates for the preparation of the optically active compounds of the formula (I)

wherein
R ^{1 is} an aromatic or heteroaromatic group which can be optionally substituted,
R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and
R ^{3 is} X or -NH ₂ , in which X is a conventional leaving group and that labeled carbon atom has the (R) configuration with an enantiomeric excess (ee) of more than 50%, preferably more than 80%, more preferably more than 90%, more preferably more than 95 and most preferably more than 98 to 100%.

With regard to the preferred meanings of the substituents R ¹ , R ² and R ⁹ , reference can be made to the above explanations of the compounds of the formulas (I), (II) and (IV).

worin
A N oder CR⁴ ist, worin
R⁴ aus der Gruppe ausgewählt wird, die aus Wasserstoff und Halogen besteht,
R⁵ aus der Gruppe ausgewählt wird, die aus Wasserstoff, Halogen, Cyano, Hydroxy, gegebenenfalls substituiertem Amino, gegebenenfalls substituiertem Alkyl und gegebenenfalls substituiertem Hydroxy besteht, oder
R⁴ und R⁵ gemeinsam einen zweiwertigen, gesättigten oder ungesättigten Kohlenwasserstoffrest mit bis zu 4 Kohlenstoffatomen bilden, der durch Oxo substituiert sein kann und eine Gruppe -NH- aufweisen kann,
R⁶ aus der Gruppe ausgewählt wird, die aus Wasserstoff, gegebenenfalls substituiertem Amino und gegebenenfalls substituiertem Hydroxy besteht,
R⁷ aus der Gruppe ausgewählt wird, die aus Wasserstoff, Halogen, Cyano, Hydroxy, gegebenenfalls substituiertem Amino, gegebenenfalls substituiertem Alkyl und gegebenenfalls substituiertem Hydroxy besteht,
B N oder CR⁸ ist, worin
R⁸ aus der Gruppe ausgewählt wird, die aus Wasserstoff und Halogen besteht, oder
R⁷ und R⁸ gemeinsam einen zweiwertigen, gesättigten oder ungesättigten Kohlenwasserstoffrest mit bis zu vier Kohlenstoffatomen bilden, der durch Oxo substituiert sein kann und eine Gruppe -NH- aufweisen kann,Thus, R ^{1 is} preferred in a preferred embodiment of the formulas (II) and (IV) or (VIII) or (IX) a group of formula (VI);

wherein
Is AN or CR ⁴ , wherein
R ^{4 is} selected from the group consisting of hydrogen and halogen,
R ^{5 is} selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino, optionally substituted alkyl and optionally substituted hydroxy, or
R ⁴ and R ⁵ together form a divalent, saturated or unsaturated hydrocarbon radical with up to 4 carbon atoms, which can be substituted by oxo and can have a group -NH-,
R ^{6 is} selected from the group consisting of hydrogen, optionally substituted amino and optionally substituted hydroxy,
R ^{7 is} selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino, optionally substituted alkyl and optionally substituted hydroxy,
Is BN or CR ⁸ , wherein
R ^{8 is} selected from the group consisting of hydrogen and halogen, or
R ⁷ and R ⁸ together form a divalent, saturated or unsaturated hydrocarbon radical with up to four carbon atoms which can be substituted by oxo and can have a group -NH-,

In a preferred embodiment of the formulas (II) and (IV) or (VIII) or (IX) in the group of the formula (VI) A is CR ⁴ and B is CR ⁸ , where R ⁴ and R ^{8 are} each hydrogen ,

In a preferred embodiment of the formulas (II) and (IV) or (VIII) or (IX) in the group of the formula (VI) R ⁵ and R ^{7 are selected} independently of one another from the group consisting of hydrogen, halogen, Cyano, hydroxy, hydroxyalkyl, preferably alkyl with one to three hydroxyl groups, more preferred hydroxy (C1-C6) alkyl, such as hydroxymethyl, hydroxyethyl etc., haloalkyl, preferably alkyl with at least one to three halogen atom, more preferably mono- to perhalogen (C1-C6 ) alkyl, such as trifluoromethyl etc., dialkylaminocarbonyloxy, preferably di (C1-C6) alkylaminocarbonyloxy such as dimethylaminocarbonyloxy etc., arylcarbonyloxy, preferably optionally substituted phenylcarbonyloxy such as 4-methylphenylcarbonyloxy etc., ureido and alkanoylamino, preferably (C1-C6) alkanoylamino, such as formylalkanoylamino, and / or
R ⁵ and R ⁴ and / or R ⁷ and R ⁸ form a divalent radical of the formula

In a preferred embodiment of the formulas (II) and (IV) or (VIII) or (IX), R ^{6 is} selected from the group consisting of hydrogen, amino and hydroxy.

In a preferred embodiment of the formulas (II) and (IV) or (VIII) or (IX), R ^{2 is} hydrogen.

In a preferred embodiment of the formulas (VIII) or (IX)
R ^{9 is} selected from the group consisting of halogen and -NH ₂ .

In a preferred embodiment of the formulas (VIII) or (IX)
R ^{1 is} a group of the formula (VI),
A CR ⁴ and B is CR ⁸ , wherein R ⁴ and R ^{8 are} each hydrogen,
R ⁵ and R ⁷ are chlorine,
R ⁶ is amino, and
R ² is hydrogen.

Particularly preferred substitution patterns of the aromatic or heteroaromatic group for R ¹ are those shown in the following table:

oder deren Salze, und (R)-1-(4-Amino-3,5-dichlor-phenyl)-2-aminoethanol der Formel (XI);

oder deren Salze jeweils mit einem Enantiomerenüberschuss (ee) von mehr als 50 %, bevorzugt 80 %, bevorzugter mehr als 90 %, noch bevorzugter mehr als 95 % und am meisten bevorzugt mehr als 98 bis 100%.Particularly preferred are optically active compounds of formula (IX), wherein X is a halogen atom or -NH ₂ , most preferred are (R) -1 - (4-amino-3,5-dichlorophenyl) -2-bromo- ethanol of formula (X):

or their salts, and (R) -1- (4-amino-3,5-dichlorophenyl) -2-aminoethanol of the formula (XI);

or their salts each with an enantiomeric excess (ee) of more than 50%, preferably 80%, more preferably more than 90%, even more preferably more than 95% and most preferably more than 98 to 100%.

The invention is described below of the examples illustrates

1. Synthesis of α-bromo-4-amino-3,5-dichloroacetophenone

1.1 Preparation of 4-amino-3,5-dichloroacetophenone (Step 1)

(Lit .: Lutz et al; J. Org. Chem; 12; 1947; 617, 680)

11 g (81.4 mmol) of 4-aminoacetophenone are dissolved in 1 40 ml of glacial acetic acid in a 1 liter 3-necked flask with KPG stirrer and dropping funnel. The solution is cooled to 15 ° C., in a 250 ml 2-necked flask with gas inlet tube are given 1 40 ml of glacial acetic acid. Chlorine gas is passed in until 11 g of chlorine has dissolved in the acetic acid. The chlorine solution is added to the dropping funnel and added quickly and with vigorous stirring and cooling to the aminoacetophene solution. Immediately after the addition, the mixture is quickly hydrolyzed with 0.55 liters of ice water. The white precipitate is filtered off and recrystallized from ethanol.
Yield: 8.69 g (52%)
NMR (CDCl ₃ , 500 MHz): 2.50 (-CH ₃ , 3H, s); 4.93 (H ₂ N-, 2N, s): 7.82 (aromatic H, 2H, s)

1.2 α-bromo-4-amino-3,5-dichloroacetophenone (Level 2)

(Lit .: Lutz et al; J. Org. Chem; 12; 1947; 617, 680)

In a 250 ml 2-neck flask with reflux condenser and dropping funnel, 0.5 g (2.46 mmol) of 4-amino-3,5-dichloroacetophenone in 100 ml of abs. Dissolved diethyl ether. A solution of 0.39 g of bromine in 10 ml of diethyl ether is slowly added dropwise with ice cooling. After the addition, the solution is allowed to warm to room temperature and stirred for a further 10 hours. After aqueous work-up, the organic phase is dried with sodium sulfate and the solvent is removed on a rotary evaporator. The crude product is recrystallized from ethanol.
Yield; 150 mg (21.6%)
NMR (CDCl ₃ , 500 MHz): 4.30 (-CH ₂ -Br, 2H, s): 5.09 (H ₂ N-, 2H, s). 7.86 (aromatic H, 2H, s)

2. Synthesis of (R) -1 - (4-Amino-3,5-dichloro-phenyl) -2-bromoethanol (stage 3)

The enzymatic reduction is carried out with alcohol dehydrogenase, which comes from Rhodococcus erythropolis. A crude cell extract is used which is produced by wet grinding of wet cells from a recombinant E. coli strain or the wild-type strain Rhodococcus erythropolis (see: Dissertation 2002, Shukrallah Na'amnieh, HHU-Düsseldorf: Development of a recombinant whole cell system cloning, coexpression and mutagenesis of the phenylalanine dehydrogenase from Rhodococcus sp. M4 and the "malic enzyme" from E. coli K1 2). Approx. 3 ml of crude extract are obtained from 1 g of wet mass by this method. The activity of this preparation is approx. 400 U / ml under the following conditions; photometric determination at 340 nm (ε NADH cm ² / μmol); substrate: acetophenone (10 mM), NADH (0.25 mM), MgCl ₂ (1 mM), phosphate buffer (100 mM), pH 6.5), limiting amount of enzyme, which oxidizes 1 μmol NADH per minute under the specified conditions. A round-bottomed flask of suitable size serves as the reaction vessel. During the enzymatic reduction, the flask contents are slowly (approx. 60 rpm) with an M agitator stirred.

A solution of 0.26 g of the α-bromo-4-amino-3,5-dichloroacetophenone prepared in 5 ml of DMSO is added to 92 ml of KPi buffer (100 mM, pH 6.5). 0.38 g of sodium formate (final concentration 60 mM) are added to this solution. 3 mmol of magnesium chloride hexahydrate and 0.47 mmol of NAD ⁺ are also added to this solution. The reaction is then started by adding 30.U alcohol dehydrogenase, which preferably comes from Rhodococcus erythropolis, and 60U formate dehydogenase, and the reaction flask is closed with a stopper. The temperature of the reaction solution is kept at 25 ° C during the reaction. After 20 hours the contents of the flask are filtered and transferred to a separatory funnel and extracted with 70 ml of ethyl acetate. To facilitate phase separation, 10 g of sodium chloride are added. The phases are separated, and the aqueous phase is extracted twice with 50 ml of ethyl acetate each time. The combined organic phases are dried with sodium sulfate, filtered and concentrated in a membrane pump vacuum on a rotary evaporator at a maximum of 55 ° C. as far as possible. An oily crude product is obtained from the desired product and DMSO. The desired product is purified by flash chromatography (column with a diameter of 3 cm, 90 g of silica gel, and gives 0.18 g of enantiomerically pure (R) -1 - (4-amino-3,5-dichloro-phenyl) -2- bromoethanol pure product in addition to 0.04 g from the unreacted starting material (α-bromo-4-amino-3,5-dichloroacetophenone).

The purity was determined by GC-MS analysis and H-NMR.

3. (R) -1 - (4-amino-3,5-dichloro-phenyl) -2-tert-butylaminoethanol ((R) -Clenbuterol) (Level 4)

187 mg of (R) -1 - (4-amino-3,5-dichlorophenyl) -2-bromoethanol are dissolved in 2 ml of tert-butylamine in a pressure tube and heated to 100 ° C. for 70 hours. After cooling, the mixture is diluted with diethyl ether, washed with diluted KOH and water, the org. Phase dried over magnesium sulfate and the solvent removed after filtering on a rotary evaporator. The crude product is purified by column chromatography (mobile solvent: methanol, 1% triethylamine; R _f = 0.2).
Yield: 44 mg (24.6%)
HPLC and GCMS were used to determine the product. The NMR data are correct with the references. NMR (CDCl ₃ , 500 MHz); 1.03 (-C (CH ₃ ) ₃ , 9H, s); 2.43 (-CH (OH) -CH ₂ -N-, 1H, dd, J = 11.3, J = 9.0); 2.78 (-CH (OH) -CN ₂ -N-, 1H, dd, J = 11.7, J = 3.3); 4.33 (H ₂ N-, 2H, s); 4.35 (-CH (OH) -CH ₂ -N-, 1H, dd, J = 8.79, J = 3.55); 7.19 (aromatic H, 2H, s)

Claims (24)

Process for the preparation of optically active compounds of formula (I)

wherein R ^{1 is} an aromatic or heteroaromatic group, which may be optionally substituted, R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and R ^{3 is} an optionally substituted alkyl group, optionally selected from one or more groups -O- and -NH-, or salts thereof, that (a) the reaction of an optically active compound of formula (II)

wherein R ¹ and R ^{2 are} as defined above and X is a conventional leaving group with a compound of formula (III) R 3 NH 2 (III) wherein R ^{3 is} as defined above, or (b) the reaction of an optically active compound of the formula (IV)

wherein R ¹ and R ^{2 are} as defined above, with a compound of formula (V) R 3 -X (V) wherein X and R ^{3 are} as defined above. The method of claim 1, wherein R ^{1 represents} a group of formula (VI);

wherein AN or CR ⁴ is where R ^{4 is} selected from the group consisting of hydrogen and halogen, R ^{5 is} selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino, optionally substituted alkyl and optionally substituted hydroxy, or R ⁴ and R ⁵ together form a divalent, saturated or unsaturated hydrocarbon radical with up to four carbon atoms which can be substituted by oxo and which can have a group -NH-, R ^{6 is} selected from the group consisting of hydrogen, optionally substituted amino and optionally substituted hydroxy, R 'is selected from the group consisting of hydrogen, halogen, cyano, hydroxy, optionally substituted amino, optionally substituted alkyl and optionally substituted hydroxy is BN or CR ⁸ , wherein R ^{8 is} selected from the group consisting of hydrogen and halogen, or R ⁷ and R ⁸ together form a divalent, saturated or unsaturated hydrocarbon radical having up to four carbon atoms, which may be substituted by oxo and which can have a group -NH-. The method of claim 2, wherein A is CR ⁴ and B is CR ⁸ , wherein R ⁴ and R ^{8 are} each hydrogen, The method of claim 2 or 3, wherein R ⁵ and R ^{7 are} each independently selected from the group consisting of hydrogen, halogen, cyano, hydroxy, hydroxyalkyl, haloalkyl, dialkylaminocarbonyloxy, arylcarbonyloxy, ureido and alkanoylamino, and / or R ⁵ and R ⁴ or R ⁷ and R ^{8 are} a divalent radical of the formula

form. A method according to any one of claims 2 to 4, wherein R ^{6 is} selected from the group consisting of hydrogen. Amino and hydroxy exist. A method according to claim 1 to any one of claims 1 to 5, wherein R ^{2 is} hydrogen. A process according to any one of claims 1 to 6, wherein R ^{3 is} a straight chain or branched alkyl group which optionally has one or more substituents selected from the group consisting of an aromatic and / or heterocyclic group which may be optionally substituted and hydroxy , and in which the alkyl group may optionally contain one or more groups -O and / or -NH-. A method according to any one of claims 1 to 7, wherein R ^{3 is} a branched alkyl group. A method according to any one of claims 1 to 8, wherein the compound of formula (I) in the case where A is CR ⁴ and B CR ⁸ , the (R) configuration at the labeled carbon atom with an enantiomeric excess (ee) of more than 80% and, in the case that A or BN, has the (S) configuration on the labeled carbon atom with an enantiomeric excess (ee) of more than 80%. A method according to any one of claims 1 to 9, wherein the compound of formula (I) on the labeled carbon atom has the (R) configuration with an enantiomeric excess (ee) of more than 80%. Method according to one of claims 1 to 10 for the production of (R) -Clenbuterol with an enantiomeric excess (ee) of more than 80%. Method according to one of claims 1 to 1 1, that the preparation of the compounds of formulas (II) and (IV) or salts thereof by asymmetric reduction of a compound of formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{9 is} X or -NH ₂ , wherein X is as defined above. A method according to claim 12, wherein the preparation of the compounds of formulas (II) and (IV) or Salts thereof by asymmetric, enzymatic reduction of a compound of formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{9 is} X or -NH ₂ , wherein X is as defined above. A method according to claim 13, that the preparation of the compounds of formulas (II) and (IV) or salts thereof by asymmetric reduction of a compound of formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{9 is} X or -NH ₂ , wherein X is as defined above, in the presence of an alcohol dehydrogenase and NADH to the compounds of formulas (II) and (IV). Process for the preparation of optically active compounds of formula (VIII)

wherein R ^{1 is} an aromatic or heteroaromatic group which may be optionally substituted, R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and R ^{3 is} X or -NH ₂ , where X is a conventional leaving group, or salts thereof that the asymmetric reduction of a compound of formula (VII)

wherein R ¹ and R ^{2 are} as defined above, and R ^{9 is} X or -NH ₂ , wherein X is as defined above, in the presence of an alcohol dehydrogenase and NADH. The method of claim 15, wherein R ¹ and R ^{2 are} as defined in any one of claims 2 to 6. A method according to any one of claims 1 to 16, wherein the labeled Carbon atom in the compounds of the formulas (II), (IV) and (VIII) the (R) configuration with an enantiomeric excess (ee) of more than 80%. A method according to any one of claims 14 to 17, wherein the alcohol dehydrogenase selected is made from alcohol dehydrogenase, which comes from Rhodococcus erythropolis and one of these, recombinantly produced alcohol dehydrogenase. A method according to any one of claims 14 to 18, wherein the alcohol dehydrogenase is recombinantly produced from Rhodococcus erythropolis. A method according to any one of claims 14 to 19, wherein the reaction mixture further contains formate dehydrogenase (FDH) and at least one formate for the regeneration of NAD ⁺ to NADH. Optically active compounds of the formula (IX)

wherein R ^{1 is} an aromatic or heteroaromatic group which may be optionally substituted, R ^{2 is} selected from the group consisting of hydrogen and optionally substituted alkyl, and R ^{3 is} X or -NH ₂ , where X is a conventional leaving group, and that labeled carbon atom has the (R) configuration with an enantiomeric excess (ee) of more than 50, or their salts. Optically active compounds according to claim 21, wherein X is a halogen atom or -NH ₂ . An optically active compound according to claim 21 or 22 which is (R) -1- (4-amino-3,5-dichlorophenyl) -2-bromoethanol of formula (X);

or salts thereof. An optically active compound according to claim 21 or 22 which is (R) -1- (4-amino-3,5-dichlorophenyl) -2-aminoethanol of the formula (XI):

or salts thereof.