2- INO-l,2,3,4-TETRAH ONAPHTHALENE DERIVATIVES ACTIVE ON THE CARDIOVASCULAR SYSTEM, PROCESSES FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM

The present invention relates to compounds active on the cardiovas¬ cular system and, in particular, it relates to derivatives of 2-ami- no-1 ,2,3,4-tetrahydronaphthalene and to their use in therapeutic field.

Various hydroxylated 2-amino-1 ,2,3,4-tetrahydronaphthalene deriva¬ tives are known to be agonists of dopaminergic receptors and several studies about the structure-activity relationship have been carried out to determine * the structure characteristics able to ensure the best dopaminergic activity and to avoid, at the same time, the undesired effects of dopamine.

An interesting review of these studies is collected in the paper published by H.E. Katerinopoulos and D.I. Schuster on Drugs of the Future, vol. 12(3), pages 223-253, (1987). In spite of the various studies, however, the topology of dopamin¬ ergic receptors has not been yet explained and a series of receptor models has been proposed in the last ten years.

In the field of the compounds strictly related to dopamine and/or 2-amino-l ,2,3,4-tetrahydronaphthalene, some authors have found that the presence of a C ₃ -C« alkyl group on the amino function is one of the requirements for dopaminergic activity while the structural requirements of the second substituent on the amino group have not yet been found. Nevertheless, there are several examples in literature showing that the structural features of the two substituents on the amino group can be extremely variable, in practice, and that small changes of the molecule can affect both quantitatively and qualitatively the pharmacologic activity in a relevant manner. Among the most significant examples the following are cited. European patent application No. 0 072 061 (Fisons) describes, among

the others, dopamine and amino-1 ,2,3,4-tetraidronaphthalene deriva¬ tives having a mono or di-substituted amino portion of formula

wherein

X is a -(CHa),,- chain, optionally substituted by hydroxy; n. is an integer between 1 and 7; R-, and R ₂ , the same or different, are hydrogen, alkyl or phenyl; D ₂ is hydrogen, alkyl, phenyl; alkyl substituted by phenyl substituted, in turn, by halogen, alkyl, amino, alkoxy or nitro; or D ₂ may be the phenylethyl moiety of a dopamine or a hydroxy-1 ,2,3,4-tetrahydronaphthyl moiety. Among the compounds described in European patent application No. 0072061, the compound of formula

CH ₂ ) ₆ -NH-C whose international non-proprietary name is dopexamine (The Merck Index - XI Ed., No. 3418, page 538), is the only compound, as far as we know, which has been developed and it is used in therapy in the treatment of acute cardiac insufficiency.

It is significant that dopexamine, not withstanding it was selected among the several compounds described and exemplified in European patent application No. 0072061, is an agonist of dopaminergic receptors less active than dopamine and, like dopamine, it is not absorbed when administered by oral route [A. Fitton and P. Benfield, Drugs, 39.(2), 308-330, (1990)]. European patent application No. 0142283 (Fisons) describes a class

of compounds which are analogs of dopexamine and in which the amino group of the dopamine moiety is still secondary.

In literature, there are several examples of compounds, with a catecholamine structure having the aim of keeping the favourable properties of dopexamine, also when administered by oral route, or of increasing the selectivity towards both dopaminergic receptors. As far as we know, however, none of these compounds has shown all the required characteristics. For the specific treatment of hypertension and of congestive heart failure still exists in the medical class the need of drugs which are dopaminergic agonists more potent than dopamine but are not selective towards a specific receptor subtype (D-i or D ₂ ), which do not interact with other receptor systems, especially α,β and 5-HT ₂ receptors, and, contemporaneously, which do not have either the adversed effects or the therapeutic unfavourable aspects of dopamine, such as the lack of absorption by oral route and the short action (Goodman and Gilman's - VII Ed., pages 161-163). In this connection, it is worth noting European patent application No. 0321 968 (SIMES Societa Italiana Medicinali e Sintetici S.p.A. now Zambon Group S.p.A.) which describes compounds of formula

wherein

R and Ri , the same or different, are hydrogen atoms or acyl groups derived from optionally substituted aliphatic, aromatic or het- eroaromatic carboxylic acids, from optionally substituted carba - ic or carbonic acids, or from a phosphoric acid; n and g. are an integer between 0 and 1 ; ^~

. is an integer selected from 1, 2, 3 and 4 so that n+p=1 and m+n is 2, 3 or 4; R ₂ and R ₃ , the same or different, are a hydrogen or halogen atom, an alkyl or an alkoxy group. ς

These compounds are agonists of D-, and D ₂ dopaminergic receptors, show contemporaneously an α*,-antagonist effect, do not interact with other receptor systems, but to be active by oral administration, they must be transformed into suitable pro-drugs.

We have now found agonists of dopaminergic receptors more potent 0 than dopamine, which have substantially no interaction with other receptor systems and, above all, which are absorbed by oral route and have a long duration of action.

Therefore, object of the present invention are the compounds of formula

0 wherein R-, and R ₂ , different from each other, are a hydrogen atom or an 0Y ^T group; Y and Y ^τ , the same or different, are a hydrogen atom or an acyl group derived from an optionally substituted aliphatic, aromatic 5 or heteroaromatic carboxylic acid,- from an optionally substituted carbamic or carbonic acid or from a phosphoric acid of formula

0

II-

R*-0-P- I OH 0

wherein

R_s is a hydrogen atom, a C*,-C ₆ alkyl optionally substituted by one or more groups selected from hydroxy, alkoxy, acyloxy, amino, carboxy and alkoxycarbonyl; or a phenyl; m. is an integer selected between 1 and 2; D_ is an integer from 3 to 7; R ₃ is a hydrogen atom or a C-,-C ₄ alkyl; R* and Re, the same or different, are a hydrogen or a halogen atom, a C-ι-C ₃ alkyl or alkoxy group; and pharmaceutically acceptable salts thereof.

The compounds of formula I have, at least, an asymmetric center and they exist in the form of stereoiso ers.

The compounds of formula I in the form of stereoisomeric mixtures as well as of single stereoisomers are object of the present invention. The compounds of formula I are agonists of dopaminergic receptors, are active also by oral route and have a long duration of action and they are useful in therapy in the cardiovascular field, in particu¬ lar for the treatment of arterial hypertension, congestive heart failure, renal failure, for the treatment of peripheral arteriopathies and in cerebrovascular insufficiencies. Specific examples of alkyl or alkoxy group in the meanings of R ₃ , R _A , R _β and R _< & are methyl, ethyl, n.propyl, i.propyl, n.butyl, i.butyl, sec.butyl, ter.butyl, methoxy, ethoxy, n.propoxy and i.pro- poxy.

Halogen atoms are fluorine, chlorine, bromine and iodine. The term acyl group derived from an aliphatic carboxylic acid means an acyl radical derived from a linear or branched aliphatic carbox¬ ylic acid having from 1 to 6 carbon atoms, optionally substituted by phenyl, halogen or alkoxy groups; specific examples are the acyl

groups derived from the following acids: formic, acetic, propionic, butyric, isobutyric, valeric and pivalic; acyl groups from aromatic or heteroaro atic carboxylic acids derive from benzoic or pyridine- carboxylic (2-, 3- or 4-pyridinecarboxylic) , pyrrolecarboxylic, isoxazolecarboxylic and quinolinecarboxylic acid, optionally substi¬ tuted by alkyl, alkoxy, halogen or nitro groups.

Specific examples comprise benzoyl, 2-pyridinecarbonyl, 3-pyridine- carbonyl, 4-pyridinecarbonyl, 2-chlorobenzoyl, 4-chlorobenzoyl, 2-methylbenzoyl, 3-methylbenzoyl, 4-methylbenzoyl, 2,4-dimethylben- zoyl, 4-nitrobenzoyl, 4-isobutyrylbenzoyl, 4-methoxybenzoyl, 2-me- thoxybenzoyl, 3-methoxybenzoyl.

Preferred substituents for carba ic and carbonic acids are alkyl and phenyl. Preferred compounds of formula I are the compounds in which R-* is 0Y ^T , Y, Y ^τ and R ₂ are hydrogen atoms, n_ is an integer selected from 5, 6 and 7.

Still more preferred compounds of formula I are the compounds in which Ri is OY', Y, Y ¹ and R ₂ are hydrogen atoms, n. is 6, m. is 1 , R _A and R _β , the same or different, are hydrogen atoms, methyl or methoxy groups, chlorine.

According to the common knowledge in the field of catechol deriva¬ tives, the compounds of formula I, wherein at least one among Y and Y' is different from hydrogen, are pro-drugs of the corresponding catechol compound of formula I (Y=Y'=H).

Among the compounds of formula I, preferred pro-drugs are the com¬ pounds in which one or both Y and Y ^~ , the same or different, are an acyl group derived from acetic, propionic, butyric, isobutyric acid, from optionally substituted benzoic or pyridinecarboxylic acid, from carbamic or carbonic acid.

Pharmaceutically acceptable salts of the compounds of formula I are salts with organic or inorganic acids such as, for example, hydrochloric, hydrobromic, hydriodic, nitric, sulfuric, phosphoric, acetic, aspartic, methansulfonic and 3,7-di-ter.butylnaphthalen-1 ,5- disulfonic acid (dibudinic acid).

The preparation of the compounds of formula I can be carried out according to the synthetic method described hereinafter.

The method comprises the reaction between a compound of formula

wherein

R- is a hydrogen atom or a protecting group selected, for example, from methyl, benzyl, benzoyl and 4-methoxybenzoyl; R _β and R- ₉ , different from each other, are a hydrogen atom or an -OR-? group; m. has the meanings reported for formula I; and an acid of formula

wherein n, R ₃ , R* and R _B have the meanings reported for formula I; or a reactive derivative thereof such as an acyl halide or a mixed anhydride, optionally prepared "in situ", in an inert solvent and in the presence of a base such as an alkaline carbonate or bicarbonate or a tertiary amine, in order to obtain the intermediate compounds

of formula

wherein , Q, R ₃ , R _A , R _β , R-7, Rβ, R<? have the meanings reported for formula II and III; and their reduction, carried out before or after the optional depro¬ tection of the hydroxy groups, in order to obtain the compounds of formula I.

The reduction of the compounds of formula IV can be carried out by using electrophylic reducing agents, in particular diborane option¬ ally co plexed with dimethylsulphide, tetrahydrofuran, aliphatic amines such as triethylamine or aromatic amines such as N,N-diethyl- aniline or pyridine.

Alternatively, the reduction can be carried out with nucleophylic reducing agents such as metal hydride, for example aluminum lithium hydride.

The reduction reaction is carried out in a suitable solvent such as, for example, tetrahydrofuran, diethylether or 1 ,2-dimethoxyethane. The deprotection, when needed, of the hydroxy groups is carried out according to conventional techniques such as hydrolysis or hydrogen- olysis.

The compounds of formula II are known or they can be easily prepared according to known methods (British Patent No. 1,509,454 - The Wellcome Foundation Ltd. ) . Also the compounds of formula III are known or they can be easily

prepared according to conventional methods such as the condensation between an aminoacid of formula

R ₃

!

NH-(CH ₂ )„-- _l -COOH (V) wherein R ₃ and n. have the meanings reported for formula I; and an acyl halide of formula

wherein R* and R _B have the meanings reported for formula I and X is a chlorine or bromine atom.

Alternatively, the synthetic method for the preparation of the compounds of formula I can be carried out by a different sequence of steps.

Therefore, the compounds of formula II can be reacted, first, with an aminoacid of formula V or a reactive derivative thereof, in order to obtain the intermediate of formula CH ₂ —(CH ₂ ) _m —CH ₃ R ₃

where in m, n_, R ₃ , R-7, Rβ and R ₉ have the meanings reported for formula I and II; which is then acylated with an acyl halide of formula VI, so obtaining the intermediates of formula IV. The subsequent reduction as above reported affords the compounds of formula I, object of the present invention.

The compounds of formula I in optically active form can be obtained by optical separation or by stereospecific or stereoselective syn¬ thesis by using an optically active starting compound of formula II. The preparation of the pro-drugs of formula I can be carried out by esterification of one or both the catechol hydroxy groups according to conventional methods.

Before carrying out the esterification reaction it may be useful to protect the secondary (N-R ₃ when R ₃ =H) amino group, for example as benzyloxycarbonyl derivative.

This protecting group can be easily removed after the esterifica¬ tion, for example by hydrogenolysis.

The preparation of the salts of the compounds of formula I is car¬ ried out according to conventional methods. The compounds of formula I are agonists of D-, and D ₂ dopaminergic receptors at least 2-10 times more potent than dopamine as shown in the in vitro binding tests (example 11).

In addition, they are also more potent than dopexamine as well as than the compounds described in the above cited European patent application No. 0 321 968.

The tests carried out to evaluate the interaction with other recep¬ tor systems have shown that the compounds of formula I do not sig¬ nificantly interact and therefore they are endowed with high specificity. The compounds of formula I showed to be inactive on the central nervous system and this lack of effect is a further favourable property not shared by other compounds having a catecholamine structure.

It is clear how these characteristics of receptor selectivity and specificity together with the absence of activity on the central

nervous system make the compounds of formula I particularly suitable for the treatment of cardiovascular disorders and, mainly, in the antihypertensive therapy, in the therapy of congestive heart failure, of renal failure, in the treatment of peripheral arteriopathies and cerebrovascular insufficiencies. In addition to the already underlined higher pharmacological activity, the feature that more than others distinguishes the compounds of formula I, object of the invention, is their ability to be absorbed by oral route and their long duration of action (example 12).

As a consequence, for the practical use in therapy, the compounds of formula I can be administered by infusion as well as by enteral route so differing from dopamine and from dopexamine. The therapeutic doses will be generally between 10 mg and 1 g a day and between 5 and 300 mg by oral route for each administration. The pharmaceutical compositions containing a therapeutically effec¬ tive amount of the compounds of formula I or of pharmaceutically acceptable salts thereof in a mixture with a suitable carrier are a further object of the present invention.

The pharmaceutical compositions object of the invention may be liquid, suitable for enteral or parenteral administration or, pre¬ ferably, solid such as tablets, capsules, granulates, suitable for oral administration. The preparation of the pharmaceutical _, compositions can be carried out according to traditional techniques.

Some times, in order to meet specific therapeutic or pharmaceutical requirements, in the preparation of the pharmaceutical compositions object of the present invention, it may be more convenient the use of a pro-drug of formula I.

For example, the use of a pro-drug can be useful for improving formulation properties or the compatibility with other active ingredients. "* The choice of a compound of formula I In the form of catechol (Y=γ ^ι =H) or of a corresponding pro-drug falls within the technical knowledge of the man skilled in the art.

In order to better illustrate the present invention,. the following examples are now given. 0 Example 1

Preparation of (S)-N-propyl-5.6-dimethoxy-l .2.3.4-tetrahvdro-2-naph- thylamine hvdrochloride Method A

10% Palladium on charcoal (50% water) (0.5 g) was added to a solu- 5 tion of (S)-5 _* 6-dimethoxy-1 ,2,3,4-tetrahydro-2-naphthylamine (50.0 g; 241 mmoles) and propionaldehyde (14.8 g; 255 mmoles) in ethanol 95° (300 ml).

The reaction mixture was kept under stirring and under hydrogen pressure (2.7 atm) at 35°C for 7 hours. 0 The catalyst was filtered off and the solvent was evaporated under reduced pressure. The residue was dissolved in absolute ethanol (300 ml) and a solution of hydrochloric acid in ethyl ether (15% w/v) was added up to clearly acid pH.

The precipitate was filtered and dried at 40°C under vacuum. 5 The title compound was obtained as a white solid (57.6 g). m.p. 257-262°C. ⁿ H-NMR (300 MHz, DMS0-d _& ): δ (ppm): 0.96 (t, 3H) ; 1.65-1.80 (m, 3H) ;

2.29 (m, 1H); 2.60 (rn, 1H); 2.80-3.00 (m, 4H); 3.13 (dd, 1H); 3.34

(m, 1H); 3.68 (s, 3H); 3.77 (s, 3H); 6.83 (d, 1H); 6.89 (d, 1H).

Mass (chemical ionization, isobutane, positive ions): 250 [M ^* 1 ]

By working in a similar way but using butyraldehyde instead of propionaldehyde, and hydrobromic acid instead of hydrochloric acid the following compound was prepared:

(S)-N-buty1-5.6-dimethoxy-1.2.3.4-tetrahvdro-2-naphthylam ine hvdro- bro ide m.p. 226-228°C

^■ "H-NMR (200 MHz, CDCl ₃ ) (free base): δ (ppm): 0.90 (t, 3H); 1.26-1.62 (m, 5H) ; 2.05 (m, 1H); 2.60 (m, 2H) ; 2.69 ( , 2H); 0 2.81-3.05 (m, 3H); ^* 3.77 (s, 3H) ; 3.81 (s, 3H); 6.70 (d, 1H); 6.78 (d, 1H).

Mass (chemical ionization, isobutane, positive ions): 264 [M ^* 1 ] Method B

Propionyl chloride (14.3 ml; 165 mmoles) was added to a solution of 5 (S)-5,6-dimethoxy-l ,2,3,4-tetrahydro-2-naphthylamine (31 g; 150 mmoles) and triethylamine (23 ml; 165 mmoles) in dimethylformamide

(310 ml) at room temperature and under nitrogen.

The reaction mixture was kept under stirring for 1 hour, then it was poured into water (1.5 1) and the solid was filtered and washed with 0 water.

After drying at 50°C under vacuum, (S)-N-propionyl-5,6-dimethoxy-

1 ,2,3,4-tetrahydro-2-naphthylamine (32.8 g) was obtained. m.p. 149-151°C

^" "H-NMR (300 MHz, CDCl ₃ ): δ (ppm): 1.14 (t, 3H); 1.70-1.80 (m, 1H); 5 2.02 (m, 1H); 2.18 (q, 2H); 2.57 (dd, 1H); 2.75-3.00 ( , 2H); 3.04

(dd, 1H); 3.80 (s, 3H); 3.84 (s, 3H); 4.25 (m, 1H); 5.47 (bd, 1H);

6.74 (d, 1H); 6.78 (d, 1H).

Mass (chemical ionization, isobutane, positive ions): 264 [M ^* 1 ] , 190

Borane-dimethylsulphide complex (82 ml; 854.4 mmoles) was added __ dropwise to a solution of (S)-N-propionyl-5,6-dimethoxy-1 ,2,3,4-tet-

rahydro-2-naphthylamine (22.5 g; 85.4 mmoles), prepared as above described, in anhydrous tetrahydrofuran (900 ml) at room temperature and under nitrogen. ς

The reaction mixture was heated under reflux for 1.5 hours.

After cooling to 15°C, a solution of 36% hydrochloric acid (9.5 ml) in ethanol (247 ml) was cautiously added dropwise. The reaction mixture was heated under reflux for 1 hour, then the solvent (about 500 ml) was distilled off at atmospheric pressure and 0 evaporated to dryness under vacuum.

The resultant crude was dissolved with absolute ethanol and the solution was heated under reflux obtaining, after cooling and fil¬ tration, the title compound (23 g) having the same physico-chemical and spectroscopic characteristics reported in method A. 5 By working in a similar way, the following compound was prepared:

(S)-N-butyl-5.6-dimethoxy-1.2.3.4-tetrahydro-2-naphthylam ine hvdro- bromide having the same physico-chemical and spectroscopic charac¬ teristics reported in method A.

Example 2 0 Preparation of (S)-N-propyl-5.6-dihvdroχy-l .2.3.4-tetrahvdro-2-naph- thylamine hydrobromide

A solution of (S)-N-propyl-5,6-dimethoxy-1 ,2,3,4-tetrahydro-2-naph- thylamine hydrochloride (22 g; 76.9 mmoles), prepared as described in example 1, in 48% hydrobromic acid (220 ml) was heated under 5 reflux (about 130°C) for 3 hours.

The solvent was evaporated to dryness under vacuum; the residue was dissolved with toluene and the solvent was evaporated to dryness. The resultant crude was suspended in ethyl acetate and, after fil¬ tration, the title compound (23 g) was obtained. _Q m.p. 219-222°C

ⁿ H-NMR (300 MHz, DMS0-d ₆ ): δ (ppm): 0.93 (t, 3H); 1.68 ( , 3H) ; 2.25 (m, 1H); 2.40-2.55 (m, 1H); 2.70-3.10 (m, 5H) ; 3.31 (m, 1H); 6.40 (d, 1H); 6.61 (d, 1H). Mass (chemical ionization, isobutane, positive ions): 222 [M ^* 1 ] By working in a similar way, the following compound was prepared: (S)-N-butyl-5.6-dihydroxy-1.2.3.4-tetrahvdro-2-naphthylamine hvdro- brφmjde m.p. 240-242°C ¹ H-NMR (200 MHz, DMSO-d*): δ (ppm): 0.90 (t, 3H); 1.35 (m, 2H); 1.62 (m, 3H); 2.13-3.11 ( , 7H); 3.38 (m, 1H); 6.39 (d, 1H); 6.60 (d, 1H).

Mass (chemical ionization, isobutane, positive ions): 236 [M ^* 1 ]

Example 3 Preparation of (R)-N-propyl-6.7-dihvdroxy-1.2.3.4-tetrahvdro-2-naph- thylamine hvdrochloride

10% Palladium on charcoal (50% water) (0.5 g) and triethylamine (2.1 g; 21 mmoles) were added to a solution of (R)-6,7-dihydroxy-1 ,2,3,4- tetrahydro-2-naphthylamine (5.0 g; 19 mmoles) and propionaldehyde (1.1 g; 19 mmoles) in ethanol 95° (150 ml).

The reaction mixture was kept under stirring and under hydrogen pressure (2.7 atm) at 35°C for 8 hours.

The catalyst was filtered off and the solvent was evaporated under reduced pressure. The residue was dissolved in absolute ethanol (100 ml) and a solution of hydrochloric acid in ethyl ether (15% w/v) was added up to clearly acid pH.

The solvent was evaporated and the crude was purified by chromato- graphic column on silica gel (230-400 mesh), eluent methylene chlo¬ ride:methanol:acetic acid=90:10:1. The title compound (3.8 g) was obtained as a white solid.

m.p. 201 -203°C

^" Η-NMR (200 MHz, DMS0-d _β > : δ (ppm) : 0.93 ( t , 3H) ; 1 . 56-1 .78 ( , 3H) ;

2.19 (m, 1H); 2.53-3.02 (m, 6H) ; 3.30 (m, 1H); 6.46 (s, 2H) . ** Mass (chemical ionization, isobutane, positive ions): 222 [M" ^* 1 ]

By working in a similar way but using butyraldehyde instead of propionaldehyde, the following compound was prepared:

(R)-N-butyl-6.7-dihvdroxy-1.2.3.4-tetrahvdro-2-naphthylam ine hvdro- chloride 0 m.p. 126-128°C

^■ •H-NMR (200 MHz, DMSO-d*): δ (ppm): 0.89 (t, 3H) ; 1.34 (m, 2H);

1.54-1.80 (m, 3H); 2.19 (m, 1H); 2.67-2.78 (m, 3H) ; 2.85-3.10 (m,

3H); 3.42 (m, 1H); 6.45 (5, 2H) .

Mass (chemical ionization, isobutane, positive ions): 236 [M ^** 1 ] 5 Example 4

Preparation o _f _* 6-r(2-methoxyphenoxy)acetylamino]hexanoic acid *

A solution of (2-methoxyphenoxy)acetyl chloride (24 g; 0.12 moles) in methylene chloride (26 ml) and a solution of sodium hydroxide (4.8 g; 0.12 moles) In water (26 ml) were contemporaneously added 0 dropwise, under vigorous stirring, to a solution of 6-aminohexanoic acid (13.1 g; 0.1 moles) and sodium hydroxide (4 g; 0.1 moles) in water (36 ml).

After 1 hour, the phases were separated and the aqueous phase was washed with methylene chloride, acidified with hydrochloric acid and 5 extracted with methylene chloride. The resultant organic phase was dried on anhydrous sodium sulphate and the solvent was evaporated. The resultant crude was purified by chromatographic column on silica gel (230-400 mesh), eluent methylene chloride:methanol=9:1 , obtain¬ ing the title compound (20 g). m.p. 69-70°C (ethyl acetate)

ⁿ H-NMR ( 300 MHz , CDCl ₃ ) : δ (ppm) : 1 .37 (m, 2H) ; 1 . 50-1 .70 (m, 4H) ;

2.33 ( t , 2H) ; 3.33 ( , 2H) ; 3.88 ( s, 3H) ; 4.55 ( s , 2H) ; 6. 90-7.05

(m, 4H); 7.10 (bt, 1H). ^& Mass (chemical ionization, isobutane, positive ions): 296 [M ^*** 1 ]

By working in a similar way, the following compounds were prepared:

6-r(2-chlorophenoxy)acetylaminolhexanoic acid m.p. 87-88°C

^■■ H-NMR (200 MHz, DMS0-d _A ): δ (ppm): 1.12-1.33 (m, 2H); 1.35-1.56 ( , 0 4H); 2.18 (t, 2H); 3.12 (m, 2H); 4.58 (s, 2H) ; 6.98 (m, 2H); 7.31

(dd, 1H); 7.43 (dd, 1H); 7.93 (bt, 1H); 11.98 (bs, 1H).

Mass (chemical ionization, isobutane, positive ions): 300 [M~1 ]

6-rr (2-chloro-4-methyl)phenoχy]acetylamino1hexanoic acid m.p. 92-95°C 5 --H-NMR (200 MHz, DMS0-d _A ): δ (ppm): 1.12-1.31 (m, 2H); 1.32-1.56 (m,

4H); 2.16 (t, 2H); 2.21 (s, 3H); 3.10 (m, 2H); 4.51 (s, 2H) ; 6.89

(d, 1H); 7.18 (dd, 1H); 7.26 (dd, 1H); 7.89 (bt, 1H); 12.02 (bs,

1H).

Mass (chemical ionization, isobutane, positive ions): 314 [M"-1 ] 0 6-rr (2-methoχy-4-methyl)phenoχy]acetylamino]hexanoic acid oil

^■ •H-NMR (200 MHz, CDCl ₃ ): δ (ppm): 1.24-1.42 ( , 2H) ; 1.45-1.70 (m,

4H); 2.29 (s, 3H); 2.31 (t, ^' 2H); 3.31 ( , 2H) ; 3.84 (s, 3H); 4.49

(s, 2H); 6.65-6.80 (m, 3H) ; 7.08 (bt, 1H). 5 Mass (chemical ionization, isobutane, .positive ions): 310 [M" ^* 1 ]

3-r(2-metho ^χ yphenoxy)acetylamino]propionic acid m.p. 95-97°C

^•■ H-NMR (300 MHz, DMSO-d*): δ (ppm): 2.42 (t, 2H); 3.34 ( , 2H); 3.77 and 3.79 (2s, 3H); 4.42 and 4.62 (2s, 2H) ; 6.80-7.03 (m, 4H); 7.96 (bt, 1H); 12.42 (bs, 1H).

Mass (chemical ionization, isobutane, positive ions): 254 [M ^* "1 ] 3-[(2-chlorophenoxy)acetylamino]propionic acid m.p. 143-144°C ^{5 "} "H-NMR (200 MHz, DMSO-d*): δ (ppm): 2.43 (t, 2H) ; 3.36 (m, 2H) ; 4.57 (s, 2H); 6.99 (m, 2H); 7.27 (m, 1H); 7.42 (dd, 1H); 7.98 (bt, 1H); 12.30 (bs, 1H).

Mass (chemical ionization, isobutane, positive ions):- 258 [M ^* 1 ] 3-rΓ(2-methoxy-4-methyl)phenoxy]acetylamino]propionic acid 0 oil ⁿ H-NMR (200 MHz, CDCl ₃ ): δ (ppm): 2.28 (s, 3H); 2.72 (t, 2H); 3.69 (m, 2H); 3.82 (s, 3H); 4.50 (s, 2H) ; 6.63-6.78 (m, 3H) ; 7.56 (bt, 1H).

Mass (chemical ionization, isobutane, positive ions): 268 [M ^*** 1 ] 5 Example 5

Preparation of 6-rN-methyl-N-C(2-methoxyphenoχy)acetyl]amino1hex- anoic acid

1 ,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) (12.8 g; 84 mmoles) and ethyl 6-bromohexanoate (12.3 g; 55 mmoles) were added under stirring 0 to a solution prepared by bubbling gaseous methylamine into toluene (150 ml) at -10°C for 20 minutes. The temperature was left arise up to 20°C. The reaction mixture was kept under stirring for 1 hour. The excess of methylamine was removed by bubbling nitrogen under reduced pressure up to neutral pH. 5 A solution of (2-methoxyphenoxy)acetyl chloride (5.4 g; 27 mmoles) in toluene (10 ml) was added to the reaction mixture under stirring. After 1 hour an aqueous saturated solution of sodium chloride was added and the phases were separated.

The organic phase was dried on anhydrous sodium sulphate and the _ _n solvent was evaporated under reduced pressure.

The resultant crude was purified by chromatographic column on silica gel (230-400 mesh), eluent petroleum ether (b.p. 40-70°C) :ethyl acetate=1 :1. ς

Ethyl 6-[N-methyl-N-[(2-methoxyphenoxy)acetyl]amino]hexanoate (2.6 g) was obtained.

""H-NMR (200 MHz, CDCl ₃ ): δ (ppm): 1.23 (t, 3H); 1.30-1.74 (m, 4H); 1.84 (m, 1H); 2.18-2.34 (m, 3H); 2.90 and 3.04 (2s, 3H) ; 3.30-3.45 (m, 2H); 3.85 (s, 3H); 4.10 (q, 2H); 4.71 (s, 2H); 6.79-6.99 ( , 0 4H).

Mass (chemical ionization, isobutane, positive ions): 338 [M~1 ] A solution of potassium hydroxide (1.1 g; 19.4 mmoles) in water (5 ml) was added to a solution of ethyl 6-[N-methyl-N-[ (2-methoxyphe- noxy)acetyl]aminoIhexanoate (2.5 g; 7.4 mmoles) in methanol (5 ml) 5 under stirring and at room temperature.

The reaction mixture was kept under stirring for 30 minutes, acidi¬ fied with 1N hydrochloric acid up to pH 1 and the solvent was evapo¬ rated to dryness under reduced pressure. The residue was treated with a mixture of methylene chloride and 0 water. The organic phase was dried on anhydrous sodium sulphate and the solvent was evaporated under reduced pressure. The resultant crude was purified by chromatographic column on silica gel (230-400 mesh), eluent methylene chloride:methanol:acetic acid=95:5:1. 5 The title compound (1.8 g) was obtained as an oil.

^"• H-NMR (200 MHz, CDCl ₃ ): δ (ppm): 1.30 (m, 2H); 1.42-1.69 (m, 4H); 2.28 (m, 2H); 2.91 and 3.04 (2s, 3H) ; 3.30-3.41 ( , 2H); 3.84 (s, 3H); 4.72 (s, 2H); 6.80-6.98 (m, 4H). Mass (chemical ionization, ammonia, positive ions): 310 [M~1 ]

-> ₀ By working in a similar way, the following compounds were prepared:

6-rN-methyl-N-r [ (2-chloro-4-methyl )phenoχy]acetyl] amino Ihexanoic acid

^■ •H-NMR (200 MHz, CDCl ₃ ) : δ (ppm) : 1 . 1 4-1 .71 ( , 6H) ; 2.07 (s , 3H) ; 2.30 (m, 2H) ; 2.91 and 3.06 ( 2s, 3H) ; 3.37 (m, 2H) ; 4.71 (s , 2H) ; 6.86 (dd, 1H) ; 6.96 (dd , 1 H) ; 7. 17 (dd, 1 H) .

Mass (chemical ionization, isobutane, positive ions): 328 [M" ^** 1 ] 3-rN-methyl-N-[(2-methoxyphenoxy)acetyπaminolpropionic acid m.p. 71-73°C ^" Η-NMR (200 MHz, DMS0-d _β ): δ (ppm): 2.41 and 2.60 (2t, 2H); 2.79 and 3.00 (2s, 3H); 3.50 (m, 2H) ; 3.75 (s, 3H) ; 4.72 and 4.81 (2s, 2H) ; 6.76-6.99 (m, 4H).

Mass (chemical Ionization, isobutane, positive ions): 268 [M ^* 1 ] 3-rN-methyl-N-rr(2-chloro-4-methyl)phenoxy1acetyl]amino1prop ionic acid m.p. 143-145°C

^" •H-NMR (200 MHz, CDCl ₃ ): δ (ppm): 2.24 (s, 3H) ; 2.62 and 2.69 (2t, 2H); 2.93 and 3.14 (2s, 3H) ; 3.62 and 3.76 (2t, 2H); 4.71 and 4.80 (2s, 2H); 6.85 (t, 1H); 6.96 (dd, 1H); 7.16 (dd, 1H). Mass (chemical Ionization, isobutane, positive ions): 286 [M ^* 1]

Example 6 Preparation of S-(-)-N-propyl-N-C6-(2-(2-methoχyphenoχy)ethylami- noIhexyl1-5.6-dihvdroχy-l .2.3.4-tetrahvdro-2-naphthylamine dihvdro- chloride (Compound 1 ) Method A a) Thionyl chloride (68.2 g; 573 mmoles) was added to a solution of 6-[(2-methoxyphenoxy)acetylamino]hexanoic acid (63.5 g; 215 mmoles), prepared as described in example 4, in methylene chlo¬ ride (420 ml). After 2 hours at room temperature, the reaction mixture was

evaporated to dryness under reduced pressure.

An yellow oil residue was obtained and used in the next step without any further purification. ** b) Sodium borate (66.6 g; 331 mmoles) was added under nitrogen to a solution of (S)-N-propyl-5,6-dimethoxy-1 ,2,3,4-tetrahydro-2-naph- thylamine hydrobromide (50.0 g; 165 mmoles), prepared as de¬ scribed in example 2, in water (1000 ml) .

The mixture was heated at 70°C up to complete dissolution, then 0 cooled to room temperature and methylene chloride (100 ml), potassium carbonate (178.3 g; 1.290 moles) and, under vigorous stirring, a solution of the yellow oil residue (prepared as described in the above point a) in methylene chloride (400 ml) were added to the mixture. 5 After 1 hour at room temperature, toluene (500 ml) was added.

After acidification with concentrated hydrochloric acid, the phases were separated. The aqueous phase was extracted again with methylene chloride (500 ml).

The collected organic phases were dried on anhydrous sodium 0 sulphate, filtered and the solvent was evaporated to dryness.

The resultant residue was dissolved in tetrahydrofuran (334 ml) under nitrogen and borane-dimethylsulphide complex (172.0 g; 2.143 moles) was slowly added under stirring.

The temperature spontaneously arose up to 35°C and the reaction 25 mixture was kept at this temperature for 30 minutes, then heated under reflux for 1.5 hours.

After cooling to 5°C, a solution of 37% hydrochloric acid (85.2 g; 0.864 mmoles) in methanol (643 ml) was added in 1 hour. The reaction mixture was heated under reflux for 1 hour, concen¬ trated by distilling the solvent (about 750 ml) at atmospheric

JU

pressure and then under reduced pressure up to dryness. The residue was dissolved in methanol (830 ml); the solvent was distilled off under reduced pressure, absolute ethanol (830 ml) *> was added and the solvent was distilled again. Further absolute ethanol (830 ml) and, then, a solution of hydrochloric acid in ethyl ether (10 ml; 15% w/v) were added.

After evaporation of the solvent, the residue was dissolved in absolute ethanol (660 ml); ethyl acetate (1170 ml) was added and 0 the mixture was cooled at 0-5°C for 24 hours.

The crystallized product was filtered and dried at 30°C under vacuum obtaining Compound 1 as a white solid. m.p. 193-194°C

[α] _D =-32.5° (1% in methanol) 5 -"H-NMR (300 MHz, DMS0-d _A ): δ (ppm): 0.92 (t, 3H) ; 1.34 (bs, 4H) ;

1.70 (m, 7H); 2.28 (m, 1H); 2.40-2.60 (m, 1H); 2.80-3.20 (m,-9H);

3.30 (t, 2H); 3.50 (m, 1H); 3.76 (s, 3H); 4.25 (t, 2H); 6.41 (d,

1H); 6.62 (d, 1H); 6.85-7.05 ( , 4H) .

Mass (chemical Ionization, isobutane, positive ions): 472 [M ^*** 1 ] 0 By working in a similar way the following compounds were prepar¬ ed:

(R)-N-PΓOPVI-N-T6-T2-(2-methoχyphenoxy)ethylamino]hexy1 1-6.7-

-dihvdroxy-1.2.3.4-tetrahydro-2-naphthylamine dihvdrochloride

(Compound 2) 5 ^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.78 (t, 3H); 1.19-2.06 (m, 12H);

2.45-3.13 (m, 10H); 3.30 (m, 2H) ; 3.38-3.53 (m, 1H); 3.67 (s,

1H); 4.12 (m, 2H) ; 6.46 (s, 2H); 6.77-6.92 (m, 4H) .

Mass (chemical ionization, isobutane, positive ions): 471 [M+1 ]

(S)-N-butyl-N- [6-[2-(2-methoxyphenoxy)ethylaminolhexyll-5.6- __ -dihydroxy-1.2.3.4-tetrahvdro-2-naphthylamine dihydrochloride

(Compound 3)

^• Η-NMR (200 MHz, D ₂ 0): δ (ppm): 0.75 (t, 3H); 1.11-1.67 (m, 12H);

2.16-2.46 (m, 2H); 2.36-3.15 (m, 10H); 3.29-3.34 ( , 2H); 3.41-3.57 (m, 1H); 3.69 (s, 3H); 4.11-4.16 (m, 2H); 6.48 (d, 1H);

6.61 (d, 1H); 6.81-6.93 (m, 4H).

Mass (chemical ionization, isobutane, positive ions): 485 [M+1 ]

(S)-N-butyl-N-[6-[2-(2-chlorophenoxy)ethylamino1hexyl1-5. 6-

-dihvdroxy-1.2.3.4-tetrahvdro-2-naphthylamine dihvdrochloride (Compound 4)

^" •H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.74 (t, 3H) ; 1.11-1.77 ( , 13H);

2.05-2.17 (m, 1H); 2.35-3.57 (m, 13H); 4.17-4.22 (m, 2H) ; 6.47

(d, 1H); 6.60 (d, 1H); 6.80-7.26 ( , 4H).

Mass (chemical ionization, isobutane, positive ions): 489 [M+13 (S)-N-propyl-N-r6-12-C(2-chloro-4-methyl)phenoχy]ethyla ino]-hex- yπ-5.6-dihvdroxy-1.2.3.4-tetrahydro-2-naphthylamine dihvdrochlo¬ ride (Compound 5)

^• "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.79 (t, 3H); 1.24-1.75 ( , 11H);

2.04 (s, 3H); 2.03-2.15 (m, 1H); 3.33 (m, 2H); 2.34-3.53 ( , 11H); 4.15 (m, 2H); 6.46 (d, 1H); 6.59 (d, 1H); 6.81 (d, 1H);

6.94 (dd, 1H); 7.04 (d, 1H).

Mass (chemical ionization, isobutane, positive ions): 489 [M+1 ]

(R)-N-propyl-N-[6-[2-[(2-chloro-4-methyl)phenoχy]ethylam inoIhex- yll-6.7-dihvdroxy-1.2.3.4-tetrahvdro-2-naphthylamine dihvdrochlo- ride (Compound 6)

^■ "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.79 (t, 3H); 1.20-1.69 (m, 10H); 1.47-2.06 ( , 2H); 2.09 (s, 3H); 2.53-3.08 ( , 10H); 3.26-3.31 (m, 2H); 3.40-3.55 (m, 1H); 3.66 (s, 3H); 4.06-4.11 (m, 2H); 6.48 (s, 2H); 6.60-6.77 (m, 3H). Mass (chemical ionization, isobutane, positive ions): 485 [M+1]

(S)-N-propyl-N-r3-[2-[(2-methoxyphenoxy)ethylamino1PΓQPVI1- 5.6- dihydroxy-1.2.3.4-tetrahydro-2-naphthylamine dihydrochloride

(Compound 7) ^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.8 (t, 3H) ; 1.50-2.18 (m, 6H); 2.36-3.23 (m, 10H); 3.35-3.40 (m, 2H) ; 3.47-3.60 (m, 1H); 3.67 (s, 3H); 4.14-4.19 (m, 2H) ; 6.48 (d, 1H); 6.61 (d, 1H); 6.83-6.91 (m, 4H). Mass (chemical ionization, isobutane, positive ions): 429 [M+1 ] (R)-N-propyl-N-T3-T2-T (2-chlorophenoxy)ethylaminoIPΓOPVI1-6.7- dihvdroxy-1.2.3.4-tetrahvdro-2-naphthylamine dihydrochloride (Compound 8)

^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.79 (t, 3H); 1.48-2.14 (m, 6H); 2.46-3.20 (m, 10H); 3.37-3.57 (m, 3H) ; 4.19-4.24 (m, 2H); 6.44 (s, 1H); 6.46 (S, 1H); 6.80-7.25 (m, 4H).

Mass (chemical ionization, isobutane, positive ions): 433 [M+1 ] (S)-N-butyl-N-r3-r2-r(2-methoxy-4-methyl)phenoxy1ethylamino1 pro- Pvn-5.6-dihvdroxy-1.2.3.4-tetrahvdro-2-naρhthylamine dihydro¬ chloride (Compound 9) ^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.75 (t, 3H) ; 1.11-1.30 ( , 2H) ; 1.46-1.62 (m, 2H); 2.08 (s, 3H); 1.60-2.15 (m, 2H); 1.97-2.15 (m, 2H); 2.34-3.22 (m, 10H); 3.31-3.36 (m, 2H) ; 3.44-3.57 (m, 1H); 3.64 (s, 3H); 4.12 (m, 2H); 6.46 (d, 1H); 6.61 (d, 1H); 6.60-6.78 (m, 3H). Mass (chemical ionization, isobutane, positive ions): 457 [M+1 ] (S)-N- [2-(5.6-dihydroxy-1.2.3.4-tetrahydro)naphthyl1-N-propyl- -N'-methyl-N ¹ -T2-(2-methoxyphenoxy)ethyl1-1.6-hexanediamine dihy¬ drochloride (Compound 10)

^"• H-NMR (200 MHz, D _a 0): δ (ppm): 0.78 (t, 3H) ; 1.16-2.07 (m, 12H); 2.76 (s, 3H); 2.26-3.54 ( , 13H); 3.63 (s, 3H) ; 4.15 ( , 2H);

6.41 (d, 1H); 6.57 (d, 1H); 6.74-6.86 (m, 4H).

Mass (chemical ionization, isobutane, positive ions): 485 [M+1 ]

(R)-N-butyl-N-[2-(6.7-dihvdroxy-1.2.3.4-tetrahvdro)naphth yl1-

N'-methyl-N ^τ -[2-(2-methoxyphenoχy)ethyl1-1.6-hexanediamine dihydrochloride (Compound 11 )

^" •H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.74 (t, 3H) ; 1.14-1.71 (m, 12H);

1.48-2.04 ( , 2H); 2.77 (s, 3H); 2.54-3.53 (m, 13H); 3.67 (s,

3H); 4.20 (m, 2H); 6.49 (s, 2H) ; 6.76-6.93 (m, 4H) . Mass (chemical-ionization, isobutane, positive ions): 499 [M+1 ]

(S)-N-12-(5.6-dihvdroxy-1.2.3.4-tetrahvdro)naphthyl]-N-pr opyl-

-N"-methyl-N'-[2-[ (2-chloro-4-methylIphenoxy1ethyl1-1.6-hexane- diamine dihydrochloride (Compound 12)

^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.79 (t, 3H); 1.22-1.30 ( , 4H) ; 1.47-1.71 ( , 7H); 2.02 (s, 3H); 2.02-2.13 (m, 1H); 2.80 (s, 3H);

2.32-3.18 (m, 10H); 3.35-3.50 (m, 3H) ; 4.20 (m, 2H); 6.44 (d,

1H); 6.58 (d, 1H); 6.77-6.99 (m, 3H).

Mass (chemical ionization, isobutane, positive ions): 503 [M+1 ]

(S)-N-propyl-N-[2-(5.6-dihvdroxy-1.2.3.4-tetrahvdro)napht hyl]- N'-methyl-N'-[2-(2-methoxyphenoxy)ethyl]-1.3-propanediamine dihydrochloride (Compound 13)

^• "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.78 (t, 3H); 1.46-2.15 ( , 6H) ;

2.82 (s, 3H); 2.27-3.51 (m, 13H); 3.61 (s, 3H); 4.22 ( , 2H);

6.42 (d, 1H); 6.60 (d, 1H); 6.74-6.91 (m, 4H). Mass (chemical ionization, isobutane, positive ions): 443 [M+1]

(R)-N-butyl-N-12-(6.7-dihvdroxy-1.2.3.4-tetrahvdro)naphth yl1-

N'-methyl-N'-T2-T(2-chloro-4-methyl)phenoxy1ethyll-1.3-pr opane- diamine dihydrochloride (Compound 14)

^" "H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.74 (t, 3H) ; 1.09-1.28 ( , 2H> 1.44-1.60 ( , 2H) ; 2.01 (s, 3H); 1.45-2.20 ( , 2H); 1.91-2.20 (m,

2H); 2.88 (s, 3H); 2.40-3.48 (m, 11H); 3.54 (m, 2H) ; 4.25 ⁽ m, 2H); 6.41 (s, 1H); 6.44 (s, 1H); 6.80-6.97 (m, 3H) . Mass (chemical ionization, isobutane, positive ions): 475 [M+1 ] Method B a) A solution of 4-methoxybenzoylchloride (11.8 g; 69.5 mmoles) in trifluoroacetic acid (24 ml) was added under nitrogen at 20°C to a solution of (S)-N-propyl-5,6-dihydroxy-1 ,2,3,4-tetrahydro-2- naphthylamine hydrobromide (7 g; 23.2 mmoles), prepared as described in example 2, in trifluoroacetic acid (80 ml).

The reaction mixture was kept under stirring at room temperature for 2 hours, then the solvent was evaporated to dryness. The residue was dissolved in ethyl acetate (20 ml) and a solution of hydrochloric acid in diethyl ether was added up to clearly acid pH.

The resultant solid was filtered obtaining (S)-N-propyl-5,6-di- (4-methoxybenzoyloxy)-l ,2,3,4-tetrahydro-2-naphthylamine hydro- chloride (12.5 g). m.p. 114-117°C [α] _D =-42.64° (1% in methanol)

^■ "H-NMR (300 MHz, DMS0-d _β ): δ (ppm): 0.95 (t, 3H) ; 1.60-1.80 (m, 3H); 2.55 (m, 1H); 2.60 (m, 1H); 2.75-3.05 (tn, 4H) ; 3.31 (dd, 1H); 3.47 ( , 1H); 3.76 (s, 3H) ; 3.78 (s, 3H); 6.94 (d, 2H); 7.00 (d, 2H); 7.21 (d, 1H); 7.25 (d, 1H); 7.84 (d, 2H) ; 7.92 (d, 2H) . Mass (chemical Ionization, isobutane, positive ions): 490 [M ^* "1 ] , 89. b) Ethylchlorocarbonate (2.9 ml; 27.4 mmoles) was added dropwise at -12°C under nitrogen to a solution of 6-[(2-methoxyphenoxy)ace- tylaminolhexanoic acid (8 g; 27.4 mmoles), prepared as described in example 4, and triethyla ine (2.8 ml; 27.4 mmoles ⁾ in

anhydrous dimethylformamide (240 ml).

The reaction mixture was kept under stirring for 30 minutes, keeping the temperature between -10°C and -12°C, then a solution of (S)-N-propyl-5,6-di-(4-methoxybenzoyloxy)-1 ,2,3,4-tetrahydro- • -2-naphthylamine hydrochloride (12 g; 22.8 mmoles), prepared as described in the above point a., and triethylamine (2.3 ml; 22.8 mmoles) in anhydrous dimethylformamide (200 ml) was added. The reaction mixture was kept under stirring overnight at room temperature.

After evaporation to dryness, the residue was dissolved in meth¬ ylene chloride (100 ml) and washed with water (3 x 50 ml). The organic phase was dried on anhydrous sodium sulphate and the solvent was evaporated under reduced pressure obtaining (S)-N- -propyl-N-[6-[[(2-methoxyphenoxy)acety1]amino]hexanoy1]-5,6-

-di-(4-methoxybenzoyloxy)-1 ,2,3,4-tetrahydro-2-naphthylamine as an oil crude (19 g) which was directly used in the next step. ^■ "H-NMR (300 MHz, DMS0-d _β ): δ (ppm): 0.86 (dt, 3H); 1.15-1.35 (m, 2H); 1.35-1.65 (m, 6H) ; 1.75-2.05 (m, 2H) ; 2.20-2.40 ( , 2H); 2.70-3.25 (m, 8H); 3.77 (d, 3H); 3.78 (s, 3H); 3.80 (s, 3H); 4.04 (DI, 1H); 4.43 (d, 2H) ; 6.96 (d, 2H); 7.00 (d, 2H); 6.80-7.30 ( , 6H); 7.86 (d, 2H); 7.94 (d, 2H).

Mass (chemical ionization, isobutane, positive ions): 767 [M ^* *1_, 337, 296. c) A solution of crude (S)-N-propyl-N-[6-[[ (2-methoxyphenoxy)ace- tyllaminolhexanoyl]-5,6-di-(4-methoxybenzoyloxy)-1 ,2,3,4-tetra- hydro-2-naphthylamine (18.5 g; 24.15 mmoles), prepared as de¬ scribed in above point b., and butylamine (7.16 ml; 72.5 mmoles) in absolute ethanol (510 ml) was heated under reflux and under nitrogen for 17 hours.

After evaporation to dryness, the resultant crude was purified by chromatographic column on silica gel (230-400 mesh), eluent methylene chloride, then, methylene chloride:methanol=95:5, obtaining (S)-N-propyl-N-[6-[[(2-methoxyphenoxy)acetyl]amino]hex- anoyl]-5,6-dihydroxy-1 ,2,3,4-tetrahydro-2-naphthylamine (6.3 g) which was directly used in the next step.

To a solution of this compound (6 g; 12.1 mmoles) in anhydrous tetrahydrofuran (240 ml) borane-dimethylsulphide complex (16 ml; 168.5 mmoles) was added dropwise at room temperature under ni¬ trogen.

The reaction mixture was heated under reflux for 1.5 hours. After cooling at 1-5°C, a solution of 36% hydrochloric acid (3.25 ml) in methanol (45 ml) was cautiously added dropwise. The reaction mixture was heated under reflux for 1 hour, then the solvent (about 120-150 ml) was distilled off at atmospheric pressure and then to dryness under vacuum. The crude was treated twice with methanol by evaporating to dryness each time. The resultant crude was washed with dioxane and then crystallized from absolute ethanol obtaining Compound 1 (4.5 g) having the same physico-chemical and spectroscopic characteristics reported in method A.

Example 7 Preparation of (S)-N-propyl-N-C6-r2-(2-methoxyphenoxy)ethylaminol- hexyl]-5.6-diacetoxy-1.2.3.4-tetrahvdro-2-naphthylamine dibudinate (Compound 15)

Acetyl chloride (0.4 g; 5.1 mmoles) was added under stirring at room temperature to a solution of Compound 1 (0.9 g; 1.6 mmoles), prepar¬ ed as described in example 6, in trifluoroacetic acid (7 ml). After 15 hours under these conditions, the solvent was evaporated

under reduced pressure and the resultant residue was purified by chromatographic column on silica gel (230-400 mesh), eluent methyl¬ ene chloride:methanol=88:l2. The resultant product was dissolved in water (3 ml); a solution of sodium dibudinate (0.5 g; 1.1 mmoles) in water (4 ml) and, then, methylene chloride (5 ml) were added and the phases were separated. The aqueous phase was extracted again with methylene chloride (3 ml). The collected organic phases were dried on anhydrous sodium sulphate and the solvent was evaporated under reduced pressure. Compound 15 was obtained (0.8 g) as a white solid, m.p. 165-167°C (dec.)

H-NMR (200 MHz, D ₂ 0): δ (ppm): -0.60 (bs, 2H); 0.36-0.61 (bs, 3H) ; 0.89 (t, 3H); 1.16 (s, 18H); 1.60 (bs, 3H); 2.24 (s, 6H); 2.08-3.40 (m, 17H); 3.75 (s, 3H); 4.26 (bs, 2H); 6.77-7.10 (m, 6H); 8.05 (s, 2H); 8.67 (s, 2H).

Mass (chemical ionization, isobutane, positive ions): 555 [M ^* "1 ]

Example 8 Preparation of (S)-N-propyl-N-[2-(5.6-dihvdroxy-1.2.3.4-tetrahvdro)- naphthyll-N'-benzyloxycarbonyl-N'-_ 2-(2-methoxyphenoxy)ethyl.-1.6- -hexanediamine

Potassium carbonate (3.4 g; 24.6 mmoles), water (20 ml) and benzyl- chloroformate (1.3 g; 7.7 mmoles) were added under nitrogen to a solution of Compound 1 (4.0 g; 7.3 mmples), prepared as described in example 6, in methylene chloride (200 ml) and dimethylformamide (20 ml).

After 1 hour, the reaction mixture was washed twice with an aqueous saturated solution of sodium chloride. The organic phase was dried on anhydrous sodium sulphate and the

solvent was evaporated under reduced pressure.

The residue was purified by column chromatography on silica gel

(230-400 mesh), eluent methylene chloride:methanol:toluene:formic ς acid=90:10:15:0.5, obtaining the title compound (3.6 g) as a white solid.

^■ "H-NMR (200 MHz, CDC1 ₃ ): δ (ppm): 0.99 (t, 3H) ; 1.20-1.96 ( , 12H); 2.12-2.20 (m, 1H); 2.75-3.35 (m, 8H) ; 3.38 (m, 2H);.3.65 ( , 2H) ; 3.81 (s, 3H); 4.03-4.20 (m, 2H) ; 5.11 (s, 2H) ; 6.21 (d, 1H); 6.77 0 (d, 1H); 6.73-7.38 (m, 9H) .

Mass (chemical ionization, ammonia, positive ions): 605 [M ^* 1 ]

Example 9

Preparation of (S)-N-PΓOPVI-N-f2-(5.6-di-(ethylcarbamoyloxy)-

-1.2.3.4-tetrahvdro)-naphthyl]-N ^τ -benzyloxycarbony1-N ^τ -12-(2-meth- 5 oxyphenoxy)-ethyl]-1.6-hexanediamine

A solution of (S)-N-propyl-N-[2-(5,6-dihydroxy-l ,2,3,4-tetrahydro)- naphthyl]-N'-benzyloxycarbonyl-N ¹ -[2-(2-methoxyphenoxy)ethyl]-1 ,6- hexanediamine (3.6 g; 6 mmoles), prepared as described in example 8, in ethylisocyanate (20 ml) was heated at 60°C under stirring and 0 under nitrogen for 24 hours.

The excess of ethylisocyanate was evaporated under reduced pressure and the residue was dissolved in ethyl acetate. The resultant solu¬ tion was washed with water. The organic phase was dried on anhydrous sodium sulphate and the 5 solvent was evaporated under reduced pressure.

The residue was purified by column chromatography on silica gel (230-400 mesh), eluent methylene chloride:methanol:toluene=90:5:5, obtaining the title compound (2.2 ) . ^■ "H-NMR (200 MHz, CDC1 ₃ ): δ (ppm): 0.88 (t, 3H) ; 1.18 (t, 3H) ; 1.19 ₀ (t, 3H); 1.10-1.80 ( , 12H); 1.96-2.18 ( , 1H); 2.40-3.10 Cm, 8H) ;

3. 10-3.41 (m, 6H) ; 3.65 (m, 2H) ; 3.81 ( s , 3H) ; 4.03-4.21 Cm, 2H) ; 5.02-5. 17 (m, 2H) ; 5.1 1 ( s , 2H) ; 6.72-7.36 ( m , 1 1 H) .

Example 10 Preparation of (S)-N-propyl-N-[6-[2-(2-methoxyphenoxy) thylamino]- hexyl]-5.6-di-(ethylcarbamoyloxy)-l .2.3.4-tetrahvdro-2-naphthylamine (Compound 16)

37% Hydrochloric acid (0.6 ml) and 10% palladium on charcoal (0.2 g) were added to a solution of (S)-N-propyl-N-[2-[5,6-di-(ethylcar- bamoyloxy)-1 ,2,3, -tetrahydro]naphthyl]-N'-benzyloxycarbonyl-N'-[2- (2-methoxyphenoxy)ethyl]-1 ,6-hexanediamine (2.0 g; 2.7 mmoles), prepared as described in example 9, in absolute ethanol (80 ml). The reaction mixture was kept under stirring under hydrogen pressure (2.7 atm) at room temperature for 6 hours. The catalyst was filtered off and the solvent was evaporated under reduced pressure.

The residue was purified by column chromatography on silica gel (230-400 mesh), eluent methylene chloride:methanol:toluene:ammonia= 80:10:10:0.5, obtaining Compound 16 (0.6 g). ^H-NMR (200 MHz, D ₂ 0): δ (ppm): 0.79 (t, 3H); 0.96 (t, 3H) ; 0.97 (t, 3H); 1.23-1.63 Cm, 10H); 1.58-2.13 (m, 2H); 2.37-3.15 (m, 14H); 3.30 (m, 2H); 3.48-3.65 (m, 1H); 3.68 (s, 3H); 4.12 (m, 2H); 6.77-6.97 (m, 6H).

Mass (chemical ionization, isobutane, negative ions): 611 [M-1] Example i1

Evaluation of affinity for D-, and D-*> receptors A) Receptor binding

Brains of male, Sprague-Dawley rats (200-250 g) were removed and membranes from striatal tissues were prepared according to the method described by Billard et al. in Life Sciences, ___H_ 1885,

( 1984 ) .

The tissues were homogenized in 50 mM Tris/HCl buffer, pH 7.4

(1 :100 weight/volume) .

The homogenate was centrifuged and the pellet was resuspended, centrifuged again and resuspended in 50 mM Tris/HCl buffer pH 7.4 containing 120 mM NaCl, 5mM Cl, 2mM CaCl ₂ and 1mM MgCl ₂ . The affinity for D-, receptor and for D ₂ receptor was evaluated by using [ ³ H]-SCH23390 [R(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5- phenyl-1H-3-benzazepine 7-ol hydrochloride] and [ ³ H]-domperidone (The Merck Index - XI Ed., No. 3412, page 537) as labelled lig- ands respectively.

As reference substances, dopamine and dopexamine were used. The standard incubation conditions (volume 1000 μl) for the assay in which [ ³ H]-SCH23390 was used were as follows: 50 mM Tris/HCl buffer (pH 7.4), 0.2 nM [ ³ H]-SCH23390, a membrane preparation of 130-140 μg proteins/ml.

The mixture was incubated with different concentrations of the tested compounds at 37°C for 15 minutes, filtered under vacuum through Whatman GF/C filters and then washed 4 times with 5 ml of ice-cold 50 mM Tris/HCl buffer (pH 7.4).

For D ₂ -receptor binding studies [ ³ H]-domperidone (0.3 nM) was incubated in a volume of 1000 μl containing buffer and a membrane preparation as above described. In addition bovine serum albumine CBSA) (0.01%) was added.

The mixture was incubated at 37°C for 30 minutes for each concen¬ tration of the tested compounds.

The obtained values, expressed as iCnM) , for compound 1, dopami¬ ne and dopexamine are reported in the following table.

Table 1 Affinity [ i(nM)l for D-, and D ₂ receptors of Compound 1, dopamine and dopexamine determined by binding studies on rat striatal membranes.

Compound 1 showed high affinity for both receptor sub-types being about 10 times more potent than dopamine and dopexamine on Di receptors and about 100 times more potent on D ₂ receptors. Receptor binding and DAo-agonist activity

The receptor binding tests to evaluate the affinity for Di and D ₂ receptors were repeated according to the method reported in above point A but using [ ³ H]-spiperone (Merck Index - XI Ed., No. 8707, page 1380) as labelled ligand for D ₂ receptor.

The standard incubation conditions (volume 1 ml) for the assay in which [ ³ H]-SCH23390 was used were as follows: 50 mM Tris/HCl buffer (pH 7.4), 0.2 nM [ ³ H]-SCH23390, a membrane preparation (3 mg/ml corresponding to 130-150 μg proteins/ml) , incubation tem¬ perature 37°C and incubation time 15 minutes.

The standard incubation conditions (volume 2 ml) for the assay in which [ ³ H]-spiperone was used were as follows: 50 mM Tris/HCl buffer (pH 7.4), 0.2 nM [ ³ H]-spiperone, a membrane preparation (3 mg/ml corresponding to 130-150 μg proteins/ml), incubation

temperature 37°C and incubation time 15 minutes.

The obtained values, expressed as i(μM), for compounds 1-14, dopamine and dopexamine are reported in table 2.

DA ₂ -agonist activity was evaluated as follows.

Transversal sections (2-3 mm) of rabbit ear artery were suspended In isolated organ baths containing rebs-Henseleit solution added with corticosterone (30 μM), desipramine (0.1 μM) and EDTA (10 μM). The preparation, subjected to a traction of 1 g and to an elec¬ tric stimulation with field pulses every 5 minutes (10 Hz, 1 msec, 30-60 V, 500 msec, duration) were left stabilize for about 2 hours. A dose-response curve for the compounds of the invention and for dopamine and dopexamine as reference compounds was determined and the inhibitory effect on the contraction induced by electric stimulation was evaluated.

Each preparation was submitted to three increasing concentrations allowing the recovery of the basal conditions before the subsequent administration.

The obtained values, expressed as pD ₂ (-log EC _B o), for compounds 1-14, dopamine and dopexamine are reported in table 2.

Table 2 Affinity [Ki(μM)] for Di and D ₂ receptors (receptor binding) on rat striatal membranes and DA ₂ -agonist activity (pD ₂ ) on rabbit ear artery for compounds 1-1 , dopamine and dopexamine.

Example 12 Evaluation of in vivo antihvpertensive activity

Male SHR rats, 3-4 months old, fasted 16 hours before the experiment

were used. Systolic blood pressure (SBP) and heart rate (HR) were recorded by tail cuff method in conscious animals by means of a BP

Recorder (W+W Basile, Italy). Before every pressure determination animals were maintained at 37°C for 10 minutes.

SBP and HR values were recorded before and at various times up to seven hours after treatment with the tested compounds.

The compounds were administered orally by gavage, in.a volume of 10 ml/kg, at doses between 10 and 160 mg/kg. For the administration, the compounds were suspended in carboxymethylcellulose (CMC) 0.5% in water and additioned with Tween 80 (0.3 ml/10 ml of CMC).

The obtained results, expressed as ED ₃₀ mmH _« (mg/kg p.o.) that is the dose causing a decrease of 30 mmHg from the basal value of SBP

(about 15% decrease) are the following: Compound 1: mg/kg p.o.

The results, moreover, show that the effect of the compound 1 was long lasting (about 4 hours) .

Similar results were obtained with other compounds of formula I.