FIELD OF THE INVENTION

The present invention relates to a process for preparing the compound rel-

(3R ^* ,3aS ^* ,7aS ^* )-3-benzyl-2-methyl-2,3 _I 3a,4,5,6,7,7a-octahydrobenzo[d]isoxazol-

4-one, also known by the name of BTG-1640, or a salt thereof.

STATE OF THE ART

The compound BTG-1640 (1a)

1a

and the corresponding hydrochloride were first described in the international patent application WO93/17004.

According to that briefly reported, the BTG-1640 product is obtained from the 1 ,3- dipolar cycloaddition of nitrone (3) and 2-cyclohexenone (2) according to Scheme 1 below:

Scheme 1.

The final product (1a), purified by chromatography, is obtained as an orange coloured oil from which the respective crystalline hydrochloride salt is obtained by an initial treatment with acetylchloride in methanol, removal of solvents under vacuum then recrystallization from acetone.

In the patent application, no details regarding nitrone (3) synthesis were given and it is therefore suggested to prepare said nitrone with one of the synthesis methods commonly used for preparing these substances, such as condensation of carbonyl compounds with hydroxylamine, in which case the precursors would be (4) and (5) shown below, or alternatively oxidation of secondary amines or hydroxylamine.

In attempting to prepare the nitrone of WO93/17004 with the aim of scaling up the aforedescribed synthesis to an industrial scale, freshly distilled phenylacetaldehyde (4), was condensed with N-methylhydroxylamine (5) to give the nitrone (3), which was reacted with cyclohexenone (2) to give the final product which was isolated from the reaction mixture by precipitation as a hydrochloride. Despite the apparent simplicity of the sequence involved, attempting to make nitrone (3) production reproducible has been a failure. In this respect nitrone (3), as with many aldonitrones, proved to be unstable with a strong tendency to depolymerize or to variously decompose. In this regard, it has been shown for example that condensation between phenylacetaldehyde (4) and anhydrous N- methylhydroxylamine (5) leads to the formation of a dimer of the nitrone (10), of formula:

and that this latter, in solution, slowly and irreversibly converts into other products including 3,4-diphenylpyrrole (Synthesis, 1981 , 561). Moreover, it has been established that the direct interaction between N- methylhydroxylamine , and phenylacetaldehyde results in intractable product mixtures often containing considerable amounts of unreacted phenylacetaldehyde.

Finally isolating the desired product (1a) deriving from the 1 ,3-dipolar addition reaction has proved to be very difficult without recourse to laborious chromatographic separations which are difficultly transferrable to an industrial scale.

The object of the present invention is to provide BTG-1640 in a reproducible manner and in good yields and so enabling BTG-1640 to be prepared on an industrial scale.

SUMMARY OF THE INVENTION

The aforesaid object was achieved by a process for preparing BTG-1640 i.e. rel-

(3R*,3aS*,7aS*)-3-benzyl-2-methyl-2 _J 3,3a,4,5,6,7,7a-octahydrobenzo[d]isoxazol-

4-one, or a salt thereof, comprising the following steps:

d) adding phenylacetaldehyde (4) to N-methylhydroxylamine (5) in the form of a salt in the presence of an organic base selected from the group consisting of tertiary amines NR1R2R3 where R1 , R2, R3 independently from one another represent a C- ₁ -C ₄ alkyl group, alkali or alkaline earth metal (Ci-C ₄ )alkoxides, alkali metal or alkaline earth metal (Ci-C ₄ )carboxylates;

and in the presence of an anhydrous polar solvent selected from the group consisting of C ₁ -C ₅ alcohols, formamide, dimethylformamide, dimethylsulphoxide, at a temperature within the range from O ⁰ C to 12O ⁰ C to provide, after removal of the solvent, a solid mixture of nitrone monomer (3) and dimer (10), wherein the nitrone to dimer ratio is within the range from 90:10 to 0:100

e) reacting the solid mixture obtained in step d), wherein the nitrone to dimer ratio is within the range from 90:10 to 0:100, with cyclohexenone (2);

f) subjecting the crude reaction product obtained in e), having been optionally evaporated to dryness and retaken in a water-immiscible solvent, to at least one wash with water followed by evaporating the organic phase to dryness;

g) separating the BTG-1640 as an oxalate salt (1c) by precipitating with oxalic acid added to the organic phase in the dry state; and

h) optionally freeing the BTG-1640 base from the oxalate salt.

The process of the invention allows BTG-1640 to be obtained in the form of an oxalate salt or as a free base and, from this latter, BTG-1640 to be obtained in the form of a salt other than oxalate in hectogram amounts.

Step d) of the process of the invention allows a solid mixture of nitrone (3) and dimer (10) to be obtained which is particularly stable and easily storable.

Another aspect of the invention therefore concerns a solid mixture of a monomer

(3) of formula

3 and

a dimer (10) of formula

in a ratio within the range from 90: 10 to 1 :99.

Said mixture, as produced, can be advantageously used to produce BTG-1640 by way of steps e), f), g) and optionally h).

Another aspect of the invention therefore concerns the use of the mixture for preparing BTG-1640 i.e. rel-(3R ^* ,3aS ^* ,7aS*)-3-benzyl-2-methyl-2,3,3a,4,5,6,7,7a- octahydrobenzo[d]isoxazol-4-one.

Said mixture can also be used for preparing the dimer (10) by actual crystallization of the mixture from a solvent, preferably toluene.

The invention therefore also concerns a process for preparing BTG-1640 which uses as the starting material the dimer (10) and consists of the following steps: e) reacting the dimer (10) with cyclohexenone (2);

f) subjecting the crude reaction product obtained in e), having been optionally evaporated to dryness and retaken in a water-immiscible solvent, to at least one wash with water followed by evaporating the organic phase to dryness;

g) separating the BTG-1640 as an oxalate salt (1c) by precipitating with oxalic acid added to the organic phase in the dry state; and

h) optionally freeing the BTG-1640 base from the oxalate salt. A further aspect of the invention concerns the use of the dimer (10) for preparing

BTG-1640, i.e. . rel-(3R ^* ,3aS ^* _I 7aS ^* )-3-benzyl-2-methyl-2 ₎ 3 _I 3a ₁ 4 _I 5 ₁ 6,7 ₁ 7a- octahydrobenzo[d]isoxazol-4-one.

The process of the invention allows the oxalate salt of BTG-1640 to be obtained, which by way of optional step h) is converted into the BTG-1640 free base which can itself be salified into a salt of interest. Another aspect of the invention concerns the tosylated salt of BTG-1640.

Another aspect of the invention concerns the preparation of phenylacetaldehyde used as a raw material in the process of the invention. Phenylacetaldehyde, which is used freshly distilled, is actually a known sensitizer and its handling should be if possible avoided. Phenylacetaldehyde (4) is a commercially available product; however, the degree of purity of the commercial product is very variable due to the spontaneous polymerization process to which the substance is subject and which invariably is manifested even if the substance is stored at low temperature.

Indeed phenylacetaldehyde is always distilled before being used as a reagent. A big drawback in distilling the commercial product, apart from the unpredictable outcome in terms of yield, is therefore the risk of exposure to the substance, especially when decontaminating the distillation residue in which the substance is still present.

The present invention therefore also relates to a process for preparing phenylacetaldehyde which avoids the use of commercial distilled phenylacetaldehyde and which can be used as a step preceding the process of the invention for preparing BTG-1640, as the phenylacetaldehyde obtained therefrom appears spectroscopically indistinguishable from distilled commercial aldehyde.

The process of the invention which leads to phenylacetaldehyde comprises the following steps:

a) reacting commercial phenylacetaldehyde dimethyl acetal (6) with acetyl chloride to give chloroether (7) and methyl acetate; MeCOCI

-MeCOOMe

b) adding pyridine or [2.2.2.]-1 ,8-diazabicyclooctane to the chloroether (7) and methyl acetate mixture to obtain respectively the salt (8) or the salt (9);

8 9

c) subjecting the salt (8) or the salt (9) to hydrolysis then extracting with organic solvent.

The invention also relates to the chloride salt (8) of N-(1-methoxy-2- phenylethyl)pyridinium and the chloride salt (9) of 1-(2-phenyl-1-methoxyethyl)-4- aza-1-azoniabicyclo[2.2.2]octane.

DETAILED DESCRIPTION OF THE INVENTION

The invention concerns a process for the preparation of BTG-1640, i.e. rel-

(3R ^* ,3aS*,7aS ^* )-3-benzyl-2-methyl-2 _J 3,3a,4,5,6 _J 7,7a-octahydrobenzo[d]isoxazol-

4-one comprising the following steps:

d) adding phenylacetaldehyde (4) to N-methylhydroxylamine (5) in the form of a salt in the presence of an organic base selected from the group consisting of tertiary amines NR1 R2R3 where R1 , R2, R3 independently from one another represent a Ci-C ₄ alkyl group, alkali or alkaline earth metal (Ci-C ₄ )alkoxides, alkali or alkaline earth metal (Ci-C ₄ )carboxylates;

and in the presence of an anhydrous polar solvent selected from the group consisting of Ci-C ₅ alcohols, formamide, dimethylformamide, dimethylsulphoxide at a temperature within the range from O ⁰ C to 12O ⁰ C to provide, after removal of the solvent, a solid mixture of nitrone monomer (3) and dimer (10), wherein the nitrone to dimer ratio is within the range from 90:10 to 0:100

e) reacting the solid mixture obtained in step d), wherein the nitrone to dimer ratio is within the range from 90:10 to 0:100, with cyclohexenone (2);

f) subjecting the crude reaction product obtained in e), having been optionally evaporated to dryness and retaken in a water-immiscible solvent, to at least one wash with water followed by evaporating the organic phase to dryness;

g) separating the BTG-1640 as an oxalate salt (1c) by precipitating with oxalic acid added to the organic phase in the dry state; and

h) optionally freeing the BTG-1640 base from the oxalate salt.

In step d) phenylacetaldehyde (4) is added to N-methylhydroxylamine in the form of a salt in the presence of an organic base selected from the group consisting of tertiary amines NR1R2R3 where R1 , R2, R3 independently from one another represent a CrC ₄ alkyl group, alkali or alkaline earth metal (C-ι-C ₄ )alkoxides, alkali or alkaline earth metal (C-i-C ₄ )carboxylates.

Preferably said salt is the hydrochloride of N-methylhydroxylamine, more preferably in the presence of an organic base selected from pyridine and triethylamine. Preferably the molar ratio of N-methylhydroxylamine hydrochloride to phenylacetaldehyde used overall for the reaction is about 1.2. When the organic base used is triethylamine, preferably the molar ratio of triethylamine to phenylacetaldehyde used overall for the reaction is not less than about 1.2, and even is more preferably about 1.3.

The phenylacetaldehyde is preferably added ^in portions to the N- methylhydroxylamine salt, such as to be always locally in a deficient amount relative to the N-methylhydroxylamine salt, thus advantageously avoiding the formation of reaction by-products.

Step d) takes place in the presence of an anhydrous polar solvent selected from the group consisting of C ₁ -C ₅ alcohols, formamide, dimethylformamide, dimethylsulphoxide at a temperature within the range from O ⁰ C to 12O ⁰ C. Preferably said polar solvent is methanol. The temperature of step d) is within the range from about 25 ⁰ C to about 7O ⁰ C, but advantageously within the range from about 5O ⁰ C to about 7O ⁰ C, and even more preferably within the range from about 55 ⁰ C to about 6O ⁰ C.

Step d) of adding phenylacetaldehyde (4) to N-methylhydroxylamine hydrochloride leads to the formation of a solid mixture of the dimer (10) and nitrone (3) in which the nitrone to dimer ratio is within the range from 90:10 and 0:100. The mixture is separated after solvent removal, preferably by forced evaporation to dryness, thus advantageously completing the reaction and increasing its yield. Therefore step d) can lead to a mixture of the monomer nitrone (3) and dimer (10), or just the dimer alone (10).

Preferably said solid mixture comprises the nitrone (3) and dimer (10) in a ratio within the range from 90:10 to 20:80, more preferably from 80:20 to 20:80, and even more preferably about 50:50.

Said dimer (10), whose formula is: contains three stereogenic centres represented by an asterix. The invention hence concerns the various stereoisomeric forms which are all included in the present invention. They are:

10a 10a'

10b 10b'

10c 10c'

1Od 10d" In accordance with the invention the dimer can also be obtained from the solid mixture of monomer (3) and dimer (10) by recrystallization from a solvent. Said solvent is preferably toluene.

The dimer (10) as the stable and storable form can be used for preparing BTG-

1640.

Indeed it can be the starting material for obtaining BTG-1640, by a process that comprises the following steps:

e) reacting the dimer (10) with cyclohexenone (2);

f) subjecting the crude reaction product obtained in e), having been optionally evaporated to dryness and retaken in a water-immiscible solvent, to at least one wash with water followed by evaporating the organic phase to dryness;

g) separating the BTG-1640 as an oxalate salt (1c) by precipitating with oxalic acid added to the organic phase in the dry state; and

h) optionally freeing the BTG-1640 base from the oxalate salt.

The invention therefore also concerns the use of the dimer (10) for preparing BTG- 1640, i.e. rel-(3R*,3aS*,7aS*)-3-benzyl-2-methyl-2,3,3a,4,5,6,7,7a- octahydrobenzo[d]isoxazol-4-one.

The solid mixture of the monomer (3) and dimer (10) obtained in step d) also appears as an extremely stable and storable crystalline solid, in which the nitrone (3) to dimer (10) ratio is within the range from 90:10 to 1 :99, preferably from 90:10 to 20:80, more preferably from 80:20 to 20:80, and even more preferably said ratio is about 50:50.

Another aspect of the invention concerns a solid mixture of a monomer (3) of formula

3

and

a dime.r (10) of formula

in a ratio from 90:10 to 1 :99, preferably from 90:10 to 20:80, and more preferably from 80:20 to 20:80. Said mixture even more preferably comprises the dimer (10) and the nitrone (3) in a 1 :1 ratio (50:50 mixture).

Said solid mixture is obtained in a very high yield, advantageously in accordance with step d) in excess of 90% Without being bound by any theory, the inventors of the present invention deem that the solid mixture of the dimer (10) and monomer

(3), or just the dimer (10) alone also obtainable by recrystallization from the solid mixture, is an essential element for the reaction with cyclohexenone (2) in step e) to give the final BTG-1640 product in high yields.

The invention also concerns the use of the mixture for preparing BTG-1640, i.e. rel-(3R*,3aS*,7aS*)-3-benzyl-2-methyl-2,3,3a,4,5,6 _I 7,7a-octahydrobenzo-

[d]isoxazol-4-one.

The invention hence concerns the use of the aforementioned solid mixture for obtaining BTG-1640 by way of steps e), f), g) and optionally h) described earlier.

In step e) the solid mixture, in a nitrone (3) to dimer (10) ratio of 90:10 to 0:100, reacts with cyclohexenone, preferably in a 20% excess. Said reaction is advantageously carried out over a time period within the range from 8 to 24 hours, more preferably over 16 hours at a temperature within the range from 40° to 12O ⁰ C, more preferably at 8O ⁰ C. In this manner BTG-1640 is obtained in yields within the range from 40 to 60%, preferably 50%. The solid nitrone (3)/dimer (10) mixture is reacted with cyclohexenone (2) preferably in the presence of an organic solvent selected from the group consisting of methanol, ethanol, isopropanol, MTBE, toluene, DMF, acetonitrile, an optionally halogenated hydrocarbon and benzene, more preferably toluene.

If in the reaction step e) a solvent is used, and if said solvent is other than toluene, then the crude reaction product deriving from step e) is evaporated to dryness and retaken in a water-immiscible solvent, preferably toluene, after which it is subjected to a wash with water then to evaporation (step f), before being subjected to subsequent reaction step g).

If the reaction solvent in step e) is toluene, the crude reaction product can be directly washed with water.

In step g), the BTG-1640 can be separated from the organic phase evaporated to dryness of step f), by precipitation with oxalic acid preferably in a stoichiometric amount. Said step g) of separation by precipitation preferably takes place in the presence of acetone as solvent at a temperature within the range from -25 ⁰ C to 1O ⁰ C, preferably at about -2O ⁰ C. Step g) of separating BTG-1640 by precipitation is carried out advantageously over a time period within the range from 6 to 12 hours, and preferably over about 8 hours.

According to the invention, after step g) the BTG-1640 oxalate salt (1c), obtained with a yield of about 27-32% relative to the starting monomer/dimer mixture or dimer alone, can be advantageously treated in step h), to free BTG-1640 free base (1a). Preferably this freeing step of the base from the BTG-1640 oxalate salt (1c) is carried out with anhydrous sodium carbonate in acetone. The mixture thus obtained can be filtered and evaporated to give BTG-1640 free base (1a) in a quantitative yield as a viscous oil which slowly solidifies. The BTG-1640 free base (1a) can be reacted with an acid selected from the group consisting of hydrochloric acid, fumaric acid, p-toluenesulphonic acid, preferably added in a stoichiometric amount to give respectively, BTG-1640 hydrochloride (1b), BTG-1640 fumarate (1d), BTG-1640 p-toluenesulphonate (1e) in an approximately quantitative yield as summarized in scheme 2 below:

1b free base

(HOOC^- ^COOH )

1/2

Me(C ₆ H ₄ )SO ₃ H 1d

Ie

Scheme 2.

A further aspect of the invention concerns the salt (1e), i.e. rel-(3R*,3aS*,7aS*)-3- benzyl-2-methyI-2,3,3a,4,5,6,7,7a-octahycirobenzo[d]isoxazol -4-one p- toluenesulphonate, found to be a stable salt and suitable for use as a medicament.

A further aspect of the invention concerns a process for preparing phenylacetaldehyde which comprises the following steps:

a) reacting commercial phenylacetaldehyde dimethyl acetal (6) with acetyl chloride to give chloroether (7) and methyl acetate;

MeCOCI

-MeCOOMe

b) adding pyridine or [2.2.2.]-1 ,8-diazabicyclooctane to the mixture of chloroether (7) and methyl acetate to obtain respectively the salt (8) or the salt (9);

8 9

c) subjecting the salt (8) or the salt (9) to hydrolysis and subsequent extraction with organic solvent.

In reaction step a) the phenylacetaldehyde dimethyl acetal (6) is selected as the starting commercial compound for the synthesis. According to the prior art, phenylacetaldehyde can be obtained from its acetal by acid hydrolysis; this process however proved to be complicated in that the phenylacetaldehyde resulting from the hydrolysis was unstable in the acidic hydrolysis environment.

The insolubility of the reagent and final product in water, moreover, necessitated the use of a co-solvent with the consequent complication of the product isolation procedure. The solution devised by the inventors of the present invention consists of the above process which comprises steps a)-c).

In the first step a), phenylacetaldehyde dimethyl acetal (6) reacts with acetyl chloride preferably in the absence of solvent and at room temperature. From this first step a) chloroether (7) and methyl acetate are obtained quantitatively over a period of about 24 hours. The reaction can be accelerated by operating either in the presence of a catalyst, preferably in the presence of a catalytic amount of a

Lewis acid, more preferably ZnCI ₂ , or AICI ₃ , or at temperatures above room temperature.

In step b) the chloroether (7) and methyl acetate mixture is reacted with pyridine or

[2.2.2.]-1 ,8-diazabicyclooctane to produce the salt (8) or (9), respectively, which precipitates from the reaction environment in quantitative yields relative to the starting acetal.

Another aspect of the invention concerns the N-(1-methoxy-2- phenylethyOpyridinium, chloride salt of formula :

8 and the 1-(2-phenyl-1-methoxyethyl)-4-aza-1-azoniabicyclo[2.2.2]octa ne, chloride salt of formula:

9 which, as reaction intermediates, allow phenylacetaldehyde to be obtained.

Step b) preferably takes place in the presence of acetone. The salt (8) or (9) dissolved in water undergoes a slow hydrolysis thus producing methanol, pyridinium chloride (in the case of pyridine) or [2.2.2.]-1 ,8-diazabicyclooctane chloride (in the case of [2.2.2.]-1 ,8-diazabicyclooctane) and phenylacetaldehyde which is efficiently removed from the reaction environment by extracting with an organic solvent. The organic solvent used in step c) is preferably a water- immiscible organic solvent having a boiling temperature not less than 5O ⁰ C; more preferably it is selected from the group consisting of hydrocarbons, ethers and esters, being even more preferably hexane or MTBE. The reaction preferably proceeds for 24 hours, in an inert atmosphere, with heating of the water and organic solvent mixture at reflux, the purity of the aldehyde (4) which accumulates in the organic phase remaining high, probably by virtue of the not excessively acidic conditions of the reaction environment. Evaporation of the organic phase produces an aldehyde (4) which is spectrophotometrically (13C-1 H-NMR) indistinguishable from distilled commercial aldehyde.

Advantageously the phenylacetaldehyde (4) of step d) of the process of the invention is the product obtained from step c) of the process of the invention for producing phenylacetaldehyde. Alternatively, phenylacetaldehyde (4) of step d) can be the phenylacetaldehyde of step c) of the process for preparing the phenylacetaldehyde after removing the organic extraction solvent.

Experimental part

Example 1

JA

Preparation of phenylacetaldehvde (4) from the dimethyl acetal (6)

Preparation of 1-chloro-1-methoxy-2~phenylethane (7, C ₉ H ₁₁ OCI, MW 170.6).

A mixture of phenylacetaldehyde dimethyl acetal (83.1 ml, 83.11 g, 0.50 mol) and acetyl chloride (35.6 ml, 39.25 g, 0.50 mol) was allowed to react at room temperature until complete disappearance of the phenylacetaldehyde dimethyl acetal and acetyl chloride 1 H-NMR signals, and replacement by the signals of the desired product (7) and methyl acetate (in about two days). This material, without any treatment, was used for preparing N-(1-methoxy-2-phenylethyl)pyridinium chloride (8).

1 H-NMR (CDCI3, 300 MHz) 2.03 (3H, s), 3.23, 3.24, 3.27, 3.29, 3.31 , 3.33, 3.36,

3.38(2H, part AB of an ABX system), 3.47 (3H, s), 3.64 (3H, s), 5.60, 5.61 , 5.62,

5.63(1 H, part X of an ABX system) 7.24 (5H, m).

13C-NMR (CDCI3, 75 MHz) 21.0, 46.6, 52.0, 58.4, 101.0, 127.5, 128.9, 130.2,

136.5, 172.0.

Preparation of N-(1-methoxy-2-phenylethyl)pyridinium chloride (8, C ₁₄ H ₁₆ ONCI,

MW 249.7).

The compound (7) in a mixture with methyl acetate, as obtained in the previous part, was added drop-wise to a solution of pyridine (50 ml, 48.9 g, 0.62 mol) in acetone (700 ml) over a period of 30 minutes under mechanical agitation. At the end of the addition the reaction mixture was left for a further 30 minutes under agitation at room temperature, then cooled in an ice bath. The compound (8) was collected by aspiration then washed with acetone to give a white hygroscopic solid

(110 g, 0.44 mol, 88%. yield).

1 H-NMR (MeOH-d4, 300 MHz) 3.30 (1 H, dd, J=14.1 Hz, J=6.2 Hz), 3.45 (3H,s),

3.47 (1 H, dd, J=14.1 Hz, J=6.2 Hz), 6.29 (1 H, t, J=6.2 Hz), 7.12-7.22 (5H, m), 8.12

( 2H, t, J=7.5 Hz), 8.65 (1 H, tt, J=7.5 Hz, J=1.3 Hz), 9.02 (2H, dd, J=1.3 Hz, J=7.5

Hz).

13C-NMR (MeOH-d4, 75 MHz) 43.8, 58.8, 102.6, 128.7, 129.4, 129.8, 130.7,

134.5, 142.6, 148.6.

Preparation of phenylacetaldehyde (4, C ₈ H ₈ O, MW 120.2)

A mixture consisting of N-(1-methoxy-2-phenylethyl)pyridiniurn chloride (8) (110 g,

0.44 mol), water (300 ml_) and hexane (250 ml_) was heated to reflux at 60-70 ⁰ C under a head of nitrogen for around 24 hours. Heating was suspended, the aqueous phase was saturated with NaCI and agitation was continued for about a further 30 minutes. The hexane phase was separated and the aqueous phase was washed with hexane (100 ml). Evaporation of the pooled organic phases provided phenylacetaldehyde (4) (47.58 g, 90% yield) usable for step d) of the process of the invention. Alternatively, the combined hexane extracts containing phenylacetaldehyde (4) could be used as such for the phenylacetaldehyde addition in step d) of the process of the invention.

1 H-NMR (CDCI ₃ , 300 MHz) 3.68 (2H, d, J=2.0 Hz), 7.21-7.39 (5H, m), 9.74 (1 H, t,

J=2.0 Hz).

13C-NMR (CDCI ₃₁ 75 MHz) 51.1 , 128.0, 129.6, 130.2, 132.4, 200.0

IB

Preparation of phenylacetaldehvde (4) from the dimethyl acetal (6)

Preparation of 1-chloro-1-methoxy-2-phenylethane (7, C ₉ H ₁₁ OCl, MW 170.6).

A mixture of phenylacetaldehyde dimethyl acetal (83.1 ml, 83.11 g, 0.50 mol) and acetyl chloride (35.6 ml, 39.25 g, 0.50 mol) was allowed to react at room temperature until complete disappearance of the phenylacetaldehyde dimethyl acetal and acetyl chloride 1 H-NMR signals, and replacement by the signals of the desired product (7) and methyl acetate (the reaction took about two days). This material, without any treatment, was used for the preparation of 1-(2-phenyl-1- methoxyethyl)-4-aza-1-azoniabicyclo[2.2.2]octane (9). 1 H-NMR (CDCI3, 300 MHz) 2.03 (3H ₁ s), 3.23, 3.24, 3.27, 3.29, 3.31 , 3.33, 3.36,

3.38(2H, part AB of a,n ABX system), 3.47 (3H, s), 3.64 (3H, s), 5.60, 5.61 , 5.62,

5.63(1 H, part X of an ABX system) 7.24 (5H, m).

13C-NMR (CDCI3, 75 MHz) 21.0, 46.6, 52.0, 58.4, 101.0, 127.5, 128.9, 130.2,

136.5, 172.0.

Preparation of 1-(2-phenyl- 1-methoxyethyl)-4-aza- 1-azoniabicyclo[2.2.2]octane chloride (9, C ₁₅ H ₂₃ ON ₂ CI, MW 282.8).

The compound (7) in a mixture with methyl acetate, as obtained in the previous part, was added drop-wise to a solution of 1 ,4-diazabicyclo[2.2.2]octane (69.9 g,

0.62 mol) in acetone (700 ml) over a period of 30 minutes under mechanical agitation. At the end of the addition, the reaction mixture was left for a further 30 minutes under agitation at room temperature then cooled in an ice bath. The chloride compound of 1-(2-phenyl-1-methoxyethyl)-4-aza-1~ azoniabicyclo[2.2.2]octane (9) was collected by aspiration then washed with acetone to give a white hygroscopic solid (130.1 g, 92% yield).

1 H-NMR (DMSO-CZ ₆ , 70 ⁰ C, 300 MHz) 2.80-3.00 (2H, m,), 3.07-3.12 (6H, m), 3.22

(3H, s), 3.45-3.51 (6H, m), 5.02 (1H, d, J=9.9 Hz), 7.30-7.38 ( 5H, m)

13C-NMR (MeOH-d ₄ , 75 MHz) 36.5, 45.6, 46.0, 63.6, 104.2, 128.6, 129.9, 131.3,

135.5.

Preparation of phenylacetaldehyde (4, C ₈ H ₈ O, MW 120.2)

A mixture consisting of 1-(2-phenyl-1-methoxyethyl)-4-aza-1- azoniabicyclo[2.2.2]octane chloride (9) (110 g, 0.44 mol), water (300 ml) and hexane (250 mL) was heated to reflux at 60-70 ⁰ C under a head of nitrogen for around 24 hours. Heating was suspended, the aqueous phase was saturated with

NaCI and agitation was continued for about a further 30 minutes. The hexane phase was separated and the aqueous phase was washed with hexane (100 ml).

Evaporation of the pooled organic phases provided phenylacetaldehyde (4) (47.58 g, 90% yield) usable for step d) of the process of the invention. Alternatively, the combined hexane extracts containing phenylacetaldehyde (4) can be used as such for the phenylacetaldehyde addition in step d) of the process of the invention.

1 H-NMR (CDCI ₃ , 300 MHz) 3.68 (2H, d, J=2.0 Hz), 7.21-7.39 (5H, m), 9.74 (1 H, t,

J=2.0 Hz). 13C-NMR (CDCI ₃ , 75 MHz) 51.1 , 128.0, 129.6, 130.2, 132.4, 200.0

Example 2

Preparation of BTG-1640 oxalate salt

2A. Preparation of the solid mixture ofdimer dO, CmHwOiN?, MW 298.4) and nitrone in methanol (3, CgH _n ON. MW 149.2)

To a solution consisting of N-methylhydroxylamine hydrochloride (204.0 g, 2.44 mol) and triethylamine (267.0 g, 2.64 mol) in methanol (750 ml) there was added in portions, over a 10 minute period, the phenylacetaldehyde (4) obtained from example 1A after evaporating the solvent (244 g, 2.03 mol; molar ratio of N- methylhydroxylamine hydrochloride/phenylacetaldehyde equal to 1.2; molar ratio of triethylamine/phenylacetaldehyde equal to 1.3). The addition was carried out under mechanical agitation and in such a way that the temperature did not exceed

55-6O ⁰ C. At the end of the addition, the solution thus obtained was evaporated in a rotary evaporator (water bath temperature 55-6O ⁰ C; pressure 120 mm Hg). The solid residue was suspended in 800 ml of iced water, then recovered by aspiration, washed twice with water and dried under vacuum over cone. H ₂ SO ₄ for 16 hours to provide a 50:50 mixture of monomer (3) and dimer (10) (278 g, 92%) as a colourless crystalline solid.

A sample of this solid mixture (20 g), recrystallized from toluene (50 ml) provided the dimer (10) (19.8 g).

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H ₁ d, J=5.6 Hz) ₁ 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H ₁ m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz) ₁ 4.58 (1 H ₁ d, J=4.2 Hz) ₁ 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1, 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2B. Preparation of the solid mixture of dimer dO, CIHH??O?N?, MW 298.4) and nitrone in methanol (3. CgHnON, MW 149.2)

The pooled hexane extracts (400 ml) containing phenylacetaldehyde (24 g, 2.03 mol) obtained in step c) of the process for preparing phenylacetaldehyde according to example 1A, were added drop-wise and under mechanical agitation over a 10 minute period at a temperature of 3O ⁰ C, to a methanolic solution consisting of N-me.thylhydroxylamine hydrochloride (50.1 g, 0.600 mol), triethylamine (62.13 g, 0.614 mol, methanol (170 ml). Agitation was continued at a temperature of 25 ⁰ C for 1 hour from the end of addition. The mixture was finally evaporated in the rotary evaporator at a temperature not exceeding 5O ⁰ C (P=120 mmHg) until a solid was obtained, which was retaken in 500 ml of water, filtered, washed with a portion of water equal to its volume and the collected solid dried under vacuum over cone, sulphuric acid for 16 hours. 46.7 g of a colourless crystalline solid were recovered consisting of a 20:80 mixture of monomer (3) and dimer (10) (yield 62%).

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H ₁ d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2C. Preparation of the solid mixture of Dimer (10, CIRH??O?N?, MW 298.4) and

Nitrone in dimethylformamide (3, C ₉ H ₁₁ ON, MW 149.2).

A mixture consisting of N-methylhydroxylamine hydrochloride (5 g, 0.06 mol), triethylamine (7.17 g, 0.071 mol) in 35 ml of dimethylformamide was centrifuged, to the liquid supernatant there being added freshly distilled commercial phenylacetaldehyde supplied by Sigma-Aldrich (6 g, 0.05 mol) under magnetic agitation over a period of about 5 minutes at a temperature of 35 ⁰ C. The solution was evaporated in the rotary evaporator (water bath temperature 8O ⁰ C, pressure

120 torr) and the solid recovered with a 65% yield. The H-NMR spectrum shows the complete disappearance of phenylacetaldehyde, the composition of the momomer/dimer mixture being in this case 35:65.

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H ₁ d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m). 13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2D. Preparation of the solid mixture of dimer (10, C1HH97O9N9, MW 298.4) and nitrone in methanol (3, CQHI ₁ ON, MW 149.2)

Freshly distilled commercial phenylacetaldehyde (4) (10 g, 83.3 mmol) was added in portions to a solution consisting of N-methylhydroxylamine hydrochloride (13.9 g, 166.7 mmol) and triethylamine (12.6 g, 125 mmol) in methanol (50 ml). The addition was carried out under magnetic agitation at a temperature of about 4O ⁰ C over a period of about 5 minutes. The solution, after about 10 minutes, was kept at 4 ⁰ C for 12 hours. The solid, recovered by aspiration with a yield of about 62%, had a monomer/dimer composition equal to 90:10.

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1, 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2E. Preparation of the solid mixture of dimer (10, C73/-/22O2/V?, MW 298.4) and nitrone in methanol (3, CgH ₁₁ ON, MW 149.2)

Freshly distilled commercial phenylacetaldehyde (4) (10 g, 83.3 mmol) was added in portions to a solution consisting of N-methylhydroxylamine hydrochloride (10.4 g, 125 mmol) and triethylamine (16.8 g, 166.7 mmol) in methanol (50 ml). The addition was carried out under magnetic agitation at a temperature of about 35 ⁰ C over a period of about 5 minutes. The solution, after 10 minutes, was kept at 4 ⁰ C for 12 hours. The solid, recovered by aspiration with a yield of about 63%, gave a monomer/dimer composition equal to 35:65.

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m). 13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2 F. Preparation of the solid mixture ofdimer dO. CiftHπOϊN?, MW 298.4) and nitrone in methanol (3. C ₃ H ₁₁ ON, MW 149.2)

Freshly distilled commercial phenylacetaldehyde (22.3 g, 186 mmol) was added in successive portions, under magnetic agitation, to a solution consisting of N- methylhydroxylamine hydrochloride (18.6 g, 223 mmol) and triethylamine (21.8 g,

216 mmol) in methanol (100 ml) at a temperature of about 4O ⁰ C over a time period of about 5 minutes. The solution was left at room temperature and after one night the methanol was evaporated in the rotary evaporator (T = about 5O ⁰ C and P = about 120 mm Hg) until a solid was obtained. Finally water and ice (100 ml) were added and the resulting suspension was filtered by aspiration. 18.6 g of mixture having a monomer/dimer composition of 20:80 (67% yield) was recovered.

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1H, d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

nitrone in methanol (3, CsHiiON, MW 149.2)

Freshly distilled commercial phenylacetaldehyde (28.85 g, 245 mmol) was added in successive portions, under magnetic agitation, to a solution consisting of N- methylhydroxylamine hydrochloride (24 g, 288 mmol) and triethylamine (29.8 g,

295 mmol) in methanol (100 ml), controlling the temperature such that it never exceeded 25 ⁰ C. The addition was completed in about 5-10 minutes. Once a homogenous solution was attained (about 5-10 minutes were needed), agitation was stopped and the solution left at room temperature until obvious formation of the first crystals after about 15 minutes, at which time the mixture was cooled to

4 ⁰ C for 12 hours and finally filtered. The residue was washed with methanol then with water followed by drying over cone, sulphuric acid under vacuum. 25.75 g of a colourless solid were recovered having a monomer/dimer composition of about

66:33 (69% yield).

From the mother liquors treated with an equal volume of water and cooled to 4 ⁰ C a further 5 g of solid product were recovered consisting of a monomer/dimer mixture having a composition of about 10:90 (14% yield).

The process allowed a total amount of product equal to 30.75 g to be obtained, consisting of a monomer/dimer mixture having a composition of 65:35 (total yield of the process equal to about 83%).

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H ₁ m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2H. Preparation of the solid mixture ofdimer dO, CinHπOzN?, MW 298.4) and nitrone in methanol (3, CgH ₁₁ ON, MW 149.2)

Freshly distilled commercial phenylacetaldehyde (28.85 g, 245 mmol) was added in successive portions, under magnetic agitation, to a solution consisting of N- methylhydroxylamine hydrochloride (24 g, 288 mmol) and pyridine (23.33 g, 295 mmol) in methanol (80 ml), controlling the temperature such that it never exceeded

25 ⁰ C. The addition was completed in about 5-10 minutes. Once a homogenous solution was attained (about 5-10 minutes were needed), agitation was stopped and the solution left at room temperature for 1 hour, then cooled to 4 ⁰ C for 12 hours and finally filtered. The residue was washed with methanol then with water followed by drying over cone, sulphuric acid under vacuum. 11.67 g of a colourless solid were recovered consisting of a monomer/dimer mixture having a composition of about 73:27 (32% yield).

From the mother liquors treated with an equal volume of water and cooled to 4 ⁰ C a further 44.6 g of product were recovered consisting of a monomer/dimer mixture having a composition of about 4:96 (44% yield). The process allowed a total amount of product equal to 56.27 g to be obtained, consisting of a monomer/dimer mixture having a composition of 40:60 (total yield of the process equal to about 76%).

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H ₁ s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

2I. Preparation of the solid mixture of dimer (10, CISH∞OΪN?, MW 298.4) and nitrone in methanol (3, CQHI ₁ ON, MW 149.2)

Freshly distilled phenylacetaldehyde (34.8 g, 290 mmol) was added in successive portions, under magnetic agitation, to a solution consisting of N- methylhydroxylamine hydrochloride (29.0 g, 347 mmol) and triethylamine (38 g,

376 mmol) in methanol (200 ml) over a time period of about 10 minutes and cooling in an ice bath such that the temperature did not exceed 3O ⁰ C. Water (100 ml) was added to the mixture having been left for three hours at room temperature.

The mixture, cooled to 4 ⁰ C for 5 hours was filtered by aspiration. The solid obtained was allowed to dry under an extractor hood. 33.12 g of a mixture having a monomer/dimer composition of 50:50 (76% yield) was obtained.

1 H-NMR of (3) (CDCI3, 300 MHz) 3.71 (3H, s), 3.82 (2H, d, J=5.6 Hz), 6.82 (1 H, t,

J=5.6 Hz), 7.00-7.40 (5H, m).

1 H-NMR of (10) (CDCI3, 300 MHz) 2.58 (3H, s), 2.65 (3H, s), 2.81-3.05 (3H, m),

3.73 (1 H, dd, J=8.8 Hz, J=4.2 Hz), 4.58 (1 H, d, J=4.2 Hz), 7.00-7.40 (10H, m).

13C-NMR of (3) (CDCI3, 75 MHz) 34.1 , 53.0, 127.6, 129.4, 129.5, 136.8, 139.6.

13C-NMR of (10) (CDCI3, 75 MHz) 37.1 , 43.8, 45.0, 58.9, 79.6, 100.8, 127.0,

127.5, 128.6, 128.8, 129.2, 129.9, 138.1 , 140.6.

Preparation of BTG-1640 oxalate starting from the mixture (1c. C ₁ RH ₂ T ₁ NOd, MW

290.1).

A solid 50:50 mixture of nitrone monomer and dimer obtained in example 2A

(200.0 g, 1.34 mol), cyclohexenone (155 g, 1.61 mol) and toluene (200 ml) was heated in a closed 500 ml flask at 8O ⁰ C until complete disappearance of the nitrone signal or that .of its dimer (1 H-NMR analysis); the process required about 16 hours. The reaction mixture diluted with toluene (200 ml) was washed with two portions of water (200 ml and 100 ml) and evaporated under vacuum in the rotary evaporator (water bath temperature 7O ⁰ C; pressure 115 mmHg). The composition of the residue (337 g) was estimated by 1 H-NMR assuming a mixture of BTG- 1640, cyclohexenone, toluene and free phenylacetaldehyde. The BTG-1640 content was 168 g (0.7 mol, 50% yield). The material was dissolved in a solution of oxalic acid (30.5 g, 0.35 mol) in acetone (500 ml), seeded and left at -2O ⁰ C overnight. The precipitate, collected by aspiration and washed with the minimum amount of acetone, provided BTG-1640 oxalate (121.28 g, 31.2% yield; M. p. 123- 124°C (dec.)) as a colourless crystalline solid.

1 H-NMR (DMSOdδ, 300 MHz) 1.70-1.93 (4H, superimposed multiplets), 2.18- 2.36 (2H, superimposed multiplets), 2.41 (3H, s), 2.72-2.90 (3H, superimposed multiplets), 3.37 (1 H, s, broadened), 4.28 (1 H, s, broadened), 7.15-7.30 (5H, m). 13C-NMR (DMSOd6, 75 MHz) 19.6, 25.6, 38.9, 40.1 , 44.9, 58.7, 69.4, 76.6, 126.4, 128.4, 129.7, 138.5, 161.5, 209.6.

Preparation of BTG-1640 oxalate (1c, C ₁ RH _2n NO _n , MW 290.1) starting from the dimer (10) alone

A mixture consisting of the dimer 10 (18 g, 0.06 mol), obtained by recrystallization from toluene of the monomer/dimer mixture of example 2A, cyclohexenone (14 g, 0.146 mol) and toluene (30 ml) was heated in a closed 250 ml flask to 8O ⁰ C until complete disappearance of the nitrone signal and that of its dimer (1 H-NMR analysis); the process required about 16 hours. The reaction mixture diluted with toluene (100 ml) was washed with two 50 ml portions of water and evaporated under vacuum in the rotary evaporator (water bath temperature 7O ⁰ C; pressure 115 mmHg). The composition of the residue (28 g), estimated by 1 H-NMR was identical to that obtained when starting from a monomer-dimer mixture. The material was dissolved in a solution of oxalic acid (5.4 g, 0.06 mol) in acetone (70 ml), seeded and left at -2O ⁰ C overnight. The precipitate, collected by aspiration and washed with a minimal amount of acetone, furnished BTG-1640 oxalate (9 g, 25.7% yield; M. p. 123-124 ⁰ C (dec.)) as a colourless crystalline solid. 1 H-NMR (DMSOdδ, 300 MHz) 1.70-1.93 (4H, superimposed multiplets), 2.18-2.36

(2H, superimposed multiplets), 2.41 (3H, s), 2.72-2.90 (3H, superimposed multiplets), 3.37 (1 H, s, broadened), 4.28 (1 H, s, broadened), 7.15-7.30 (5H, m).

13C-NMR (DMSOdδ, 75 MHz) 19.6, 25.6, 38.9, 40.1 , 44.9, 58.7, 69.4, 76.6, 126.4,

128.4, 129.7, 138.5, 161.5, 209.6.

Example 3

Preparation of BTG-1640 free base (1a, Ci ₅ H ₁₉ O ₂ N, MW 245.3)

A mixture consisting of BTG-1640 oxalate (1c) (200 g, 0.69 mol), anhydrous

Na ₂ CO ₃ (87.7 g, 0.83 mol) and acetone (600 ml) was maintained under mechanical agitation at reflux temperature until disappearance of the oxalate species in solution (13C NMR); transformation required about 16 hours. The reaction mixture, re-equilibrated to room temperature, was transferred to a glass column provided with a porous septum and was filtered by applying pressure. The solid in the column was washed with an equal volume of acetone. The combined filtrates were evaporated in the rotary evaporator (water bath temperature 5O ⁰ C; pressure 115 mmHg) to give BTG-1640 free base 1a (169.0 g, 100% yield) as a pale yellow viscous oil which solidified when left to stand (M. p. 35-36 ⁰ C).

1 H-NMR (CDCI3, 300 MHz) 1.70-2.04 (4H, superimposed multiplets), 2.20-2.34

(1 H, multiplet), 2.4-2.50 (1H, multiplet), 2.52 (3H, s) 2.75 (1 H, t, J=5.6 Hz) 2.82-

3.00 (2H, superimposed multiplets), 3.42-3.54 (1 H, multiplet), 4.36 (1 H, s, broadened) 7.17-7.31 (5H, m).

13C-NMR (CDCI3, 75 MHz) 20.3, 26.7, 40.2, 41.1 , 45.6, 59.8, 70.6, 77.2, 127.1 ,

129.0, 130.3, 138.5, 210.1.

The BTG-1640 free base without further treatments was used in the following preparations of the respective salts.

Example 4

Preparation of the various salts of BTG-1640 base

4A. Preparation of BTG-1640 fumarate (1d, C ₁₇ H ₂ iNO ₄ , M.p. 303.2).

To a solution of BTG-1640 free base (1a) (169 g, 0.69 mol) in methanol (350 ml) heated to reflux, there was added fumaric acid (40.0 g, 0.34 mol) in three portions; heating was continued until complete dissolution of the reagent. From the solution held at -2O ⁰ C for 16 hours a solid was then separated which, after being collected by aspiration and washed with a portion of methanol and a portion of MTBE ₁ gave

BTG-1640 fumarate (Id, 177.7 g, 0.59 mol, yield 85%) as a colourless crystalline solid.

The mother liquors concentrated in the rotary evaporator and cooled as before to -

2O ⁰ C overnight gave a second portion of BTG-1649 fumarate (1d) (10.4 g, 0.03 mol, 5% yield, 90% total yield) as a colourless crystalline solid (M. p. 110-111 ⁰ C

(dec).

1 H-NMR (DMSOd6, 300 MHz) 1.69-1.98 (4H, superimposed multiplets), 2.18-2.36

(2H, superimposed multiplets), 2.40 (3H, s), 2.70-2.92 (3H ₁ superimposed multiplets), 3.34 (1 H, s, broadened), 4.26 (1 H, s, broadened), 6.62 (1 H, s), 7.14-

7.29 (5H, m).

13C-NMR (DMSOdδ, 75 MHz) 19.7, 25.6, 38.9, 40.1 , 44.9, 58.7, 69.4, 76.5, 126.4,

128.4, 129.7, 134.2, 138.5, 166.3, 209.6.

4B. Preparation of BTG-1640 hydrochloride (1b, C ₁₅ H ₂₀ CINO ₂ , MW 281.8)

The BTG-1640 free base (1a) (10 g, 0.041 mol) was dissolved in the methanol hydrochloride obtained by cautiously adding acetyl chloride (3.20 g, 0.041 mol) to methanol (50 ml). The solution, evaporated under reduced pressure in the evaporator left a residue which, on grinding in MTBE, gave BTG-1640 hydrochloride (1 b) as a colourless crystalline solid (11.47 g, yield 100%; M. p. 151-

152 ⁰ C (dec)).

1 H-NMR (DMSOd6, 300 MHz) 1.60-2.32 (5H, superimposed multiplets), 2.42-2.58

(1 H, multiplet), 2.91 (3H, s), 3.10 (1 H, dd, J=10.2 Hz, J=13.2 Hz), 3.26-3.48 (2H, superimposed multiplets), 4.44 (1 H, s, broadened), 5.08 (1 H, s, broadened), 7.20-

7.42 (5H, m).

13C-NMR (DMSOdδ, 75 MHz) 19.8, 24.1 , 35.0, 39.9, 42.8, 56.1 , 71.3, 82.5, 127.3,

128.8, 129.6, 136.1 , 207.0.

4C. Preparation of BTG-1640 p-toluenesulphonate (1e, C ₂₂ H ₂₇ NO ₅ S, MW 417.5)

Hydrated p-toluenesulphonic acid (7.73 g, 0.041 mol) was added to a solution of

BTG-1640 free base (10 g, 0.041 mol) in acetone (50 ml) and the mixture heated to promote dissolution of the reagent. From the mixture cooled to 4 ⁰ C BTG-1640 p-toluenesulphonate (1e, 16.5 g, 97%) was separated as a colourless crystalline solid (M. p. 139-14O ⁰ C (dec.)). 1 H-NMR (DMSOd6, 300 MHz) 1.60-2,30 (5H, superimposed multiplets), 2.28 (3H, s), 2.49-2.58 (1 H ₁ m), 2.93-3.03 (1H, multiplet), 3.03 (3H ₁ s) 3.24-3.33 (2H, superimposed multiplets), 4.45 (1 H, s, broadened), 5.00 (1 H, s, broadened), 7.13 (2H, d, J=7.8 Hz), 7.20-7.40 (5H, m), 7.52 (2H, d, J=7.8 Hz).

13C-NMR (DMSOdθ, 75 MHz) 20.0, 21.O ₁ 24.1 , 35.2, 43.9, 56.0, 71.4, 82.8, 125.7, 127.3, 128.4, 128.8, 129.6, 135.9, 138.2, 145.4, 207.0.