AU707990B2 - Enantiomers of carbazole derivatives as 5-HT1-like agonists - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

a. .a Name of Applicant: Actual Inventors: Address for Service: SmithKline Beecham plc Gary Thomas BORRETT John KITTERINGHAM Roderick PORTER Mark SHIPTON Mythily VIMAL Rodney YOUNG DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000 Enantiomers of carbazole derivatives as 5-HT1-like agonists Invention Title: The following statement is a full description of this invention, including the best method of performing it known to me: Q:\OPER\PDB\SMITH.DIV- 4/7/97 P130566 Div AU

COMPOUNDS

The present invention relates to certain tetrahydrocarbazole derivatives, in particular their enantiomeric forms, processes for preparing them, pharmaceutical compositions containing them and their use in therapy, in particular the treatment of migraine.

International Patent Application W093/00086 describes compounds of the formula 1 23 R NR R

H

and salts thereof for use in the treatment of conditions wherein a 5-FHT 1 -like agonist is indicated, in particular migraine.

In the above compounds R 1 represents hydrogen, halogen, trifluoromethyl, nitro, hydroxy, C1 6 alkyl, C1-6alkoxy, arylC1-6alkoxy, -CO 2

R

4 -(CH29nCN, (CH2)nCONR 5

R

6

-(CH

2 )nSO 2

NR

5

R

6

C

1 -6alkanoylamino(CH 2 n, or C1-6alkylsulphonylamiino(CH 2

R

4 represents hydrogen, C 1 -6alkyl or ariylC1-6alkyl;

R

5 and R 6 each independently represent hydrogen, or C1-6alkyl, or R 5 and R 6 together with the nitrogen atom to which they are attached form a ring; nii represents 0, 1 or 2; and

R

2 and R 3 each independently represent hydrogen, C 1 -6alkyl or benzyl or together with the nitrogen atom to which they are attached form a pyrrolidino, piperidino or hexahydroazepino ring. The carbon atom to which the group NR 2

R

3 is attached at position 3 of the tetrahydrocarbazole riing) is an asymmetric carbon atom and hence the compounds exist as optically active enantiomers.

W093/00086 describes inter alia the preparation of the above compounds wherein

R

1 is -C(O)NH 2 one of R 2 and R 3 is hydrogen and the other is methyl or ethyl, viz 6 -carboxamido-3-N-methylamino I-1, 2 ,3,4-tetrahydrocarbazole (as the hydrochloride salt) and 6-carboxamido-3-N-ethylamino -1,2,3,4-tetrahydrocarbazole (as the oxalate salt).

Both compounds were obtained only as mixtures of enantiomers.

We have now isolated the individual isomers of the above compounds. Thus, in a 30 first aspect the present invention provides the enantiomer of a compound of formula (I) P:\OI'ER\PDB\28517-97.138 19/5/99 Forntla (I) wherein R 1 is ethyl, or a salt, solvate, hydrate thereof, substantially free from the corresponding enantiomer.

In accordance with convention the and designations indicate the direction of rotation of plane-polarised light by the compounds. The prefix indicates that the isomer is dextrorotatary (also designated d) and the prefix indicates the laevorotatory isomer (also designated The R and S designations denote the absolute configuration as determined by X-ray crystallography.

Salts, solvates and hydrates of the above named compounds are also within the scope of the present invention.

It will be appreciated that for use in medicine a physiologically acceptable salt should be employed. Suitable physiologically acceptable salts will be apparent to those skilled in the art and include for example acid addition salts such as those formed with inorganic acids e.g.

hydrochloric, hydrobromic, sulphuric or phosphoric acids and organic acids e.g. succinic, tartaric, malonic, citric, maleic, acetic, fumaric or methanesulphonic acid. Other nonphysiologically acceptable salts e.g. oxalates may be used for example in the isolation of enantiomers of formula and are included within the scope of this invention. Also included within the scope of the invention are solvates and hydrates of enantiomers of formula and 20 their salts.

Acids which have more than one carboxyl group e.g. succinic, tartaric, malonic or citric acids may correspondingly react with more than one molecule of an enantiomer for example succinic acid may react with either one or two molecules of to form either a 1:1 salt (succinate) or a 2:1 salt (hemi-succinate). All such salt forms are encompassed by the 25 present invention; in general the 1:1 salt form is preferred.

Specific salts according to the present invention include; (+)-6-carboxamido-3-N-methylamino- 1,2,3,4-tetrahydrocarbazole succinate and (+)-6-carboxamido-2-N-ethylamino-1,2,3,4-tetrahydrocarbazole hydrochloride.

It will be appreciated that an enantiomer according to the present invention namely the (+)-enantiomer, will be substantially free from the corresponding enantiomer.

Preferably, a specific enantiomer of the invention will contain less than 10%, e.g. less than 5% and advantageously less than 1% e.g. less than 0.5% of its opposite enantiomer.

S^ In vitro testing (rabbit basilar artery) indicates that for the ethyl derivative of formula P:\OPER\PDB\28517-97.138 -19/5/99 the enantiomer is more active that the corresponding enantiomer.

Enantiomers of formula may be prepared by standards methods, for example: Separation of an enantiomeric mixture of a compound of formula or a derivative thereof by chromatography on a chiral HPLC column.

Separation of diastereoisomers of a chiral derivative a chiral salt) of a compound of formula e.g. by crystallisation, or by a chromatography.

Alkylation of the enantiomer of 3 -amino-6-carboxamido-l,2,3,4tetrahydrocarbazole or a salt thereof, followed if necessary or desired by converting a derivative of compound so obtained into a compound of formula itself or a different derivative thereof e.g. by removal of any Nprotecting group or facilitating group, conversion of a salt into the free base, and/or salt formation.

Separation according to process is generally facilitated by first introducing a readily removable group into the alkylamino moiety of the compound of formula Suitable removable facilitating groups include those commonly used as N-protecting groups e.g. an alkoxycarbonyl group such as t-butyloxycarbonyl or an aralkoxycarbonyl group such as benzyloxycarbonyl which groups may be introduced by reaction with for example a di-alkyldicarbonate such as di-t-butyl-dicarbonate or a chlorformate such as benzylchloroformate.

The resulting enantiomer mixture can be applied to a chiral HPLC column and fractions 20 containing the individual isomers collected. A facilitating group may be removed by standard methods such as acid hydrolysis or catalytic hydrogenation.

A chiral derivative according to process is a derivative containing at least two chiral centres, such that an enantiomeric mixture of a compound is converted into a pair of diastereoisomers. Such derivatives include chiral salts wherein the anion contains a chiral 25 centre and derivatives of formula in which the alkylamino moiety is substituted by a group containing a chiral centre.

A chiral salt may be prepared for example by reaction of an enantiomeric mixture, *such as a 1:1 racemate, of a compound with an optically active acid such as camphorsulphonic acid, d-tartaric acid, 1-malic acid, 1-mandelic acid, 1-gulonic acid, 2,3:4, 6 -di-O-isopropylidene-2-keto-L-gulonic acid or R- 2 -pyrrolidone-5-carboxylic acid (also P:\OPER\PDB\28517-97.138 19/5/99 3 known as D-pyroglutamic acid) to give two diastereoisomeric salts which may be separated e.g. by crystallisation. The free base form of the desired enantiomer may be obtained by neutralisation with a base such as sodium hydroxide or an ion exchange resin. Preferred optically active acids for use in this process include (1S)-(+)-camphorsulphonic acid and especially R- 2 -pyrrolidone-5-carboxylic acid.

Alternatively, an optically active reagent such as R-a-methylbenzyloxy-succinimidate may be reacted with an enantiomeric mixture of formula to give a mixture of diastereoisomers which can be separated by chromatography, followed by hydrogenolysis to give the desired enantiomer of formula 2 a.

of..

a *e *ee e P30566 Div AU A chiral derivative may also be prepared by employing a chiral auxiliary at an earlier stage in the synthesis as described hereinafter. This may advantageously result in a mixture enriched with one diastereoisomer of a compound and most preferably a single diastereoisomer, thus providing a stereoselective synthesis of an enantiomer according to the invention.

Alkylation of an enantiomer of 3 -amino-6-carboxamido-1,2,3,4-tetrahydrocarbazole according to process may be carried out by standard methods well known in the art. For example alkylation may be achieved indirectly by formation of a group which can be reduced to the desired alkylamino function (reductive alkylation). Thus for example the 3-amino compound can be reacted with an appropriate aldehyde or ketone e.g.

formaldehyde, acetaldehyde or acetone, in the presence of a suitable reducing agent such as an alkali metal borohydride or cyanoborohydride e.g. sodium cyanoborohydride.

Alternatively formylation may be effected using p-nitrophenol formate in aqueous tetrahydrofuran, using similar reducing conditions. Preferably, the 3-amino compound is first reacted with benzaldehyde, also in the presence of a reducing agent such as a cyanoborohydride, to form 3-N-benzylamino-6-carboxamido-1,2,3,4-tetrahydrocarbazole, prior to introduction of the methyl or ethyl group. The benzyl group may subsequently be cleaved by standard methods such as catalytic hydrogenation.

In a further alkylation method, an N-methyl substituent may be introduced by formation of a 3-isothiocyanato derivative e.g. by reaction of the 3-amino compound with carbon disulphide and dicyclohexylcarbodiimide; followed by reduction for example with a borohydride.

It will be appreciated by those skilled in the art that other standard means of alkylation may also be employed.

25 The starting compounds for use in the above processes may be prepared by methods known in the art for the preparation of tetrahydrocarbazoles, such as the methods described in International Application W093/00086. Thus for example an enantiomeric mixture of formula may be prepared by reductive alkylation of the corresponding 3amino compound, as described for process above.

30 An enantiomeric mixture of formula may also be prepared by reaction of 4 -carboxamido-phenylhydrazine, or a salt thereof e.g. the hydrochloride, with 4-(methyl or ethyl)-aminocyclohexanone. In a particular embodiment of this method a protected derivative of the 4 -alkylaminocyclohexanone is advantageously employed, e.g. a ketal of formula (II) -4- P30566 Div AU 1 2 NR R O O

A

Formula (IT) wherein R 1 is as defined for formula R 2 is hydrogen or an N-protecting group and A is an alkylene moiety, such as ethylene or neopentylene (-CH 2

C(CH

3 2

CH

2 Compounds of formula (II) may themselves be prepared from a protected 1,4-cyclohexane-dione of formula (III): 0 O O

A

Formula (III) by reaction with the appropriate alkylamine compound. This reaction may be effected in a suitable solvent, for example a hydrocarbon such as benzene or toluene in the presence of titanium tetrachloride or suitable molecular sieves e.g. 4A molecular sieves, to give the corresponding iminoketal derivative which may then be converted to an alkylamino compound of formula (II) by catalytic hydrogenation using for example palladium on carbon. Alternatively the reaction may be effected in a solvent such as an alcohol e.g.

ethanol and the mixture hydrogenated directly, using e.g. palladium on charcoal, to give a compound of formula (II).

The alkylamino group in the resulting compound of formula (II) may if desired be protected using standard methods. Suitable N-protecting groups are well-known in the art and include for example acyl groups such as acetyl, trifluoroacetyl, or benzoyl; an alkylor aralkyloxycarbonyl group such as methoxycarbonyl, t-butoxycarbonyl, benzyloxycarbonyl or phthaloyl; and aralkyl groups such as benzyl, diphenylmethyl or triphenylmethyl. The protecting groups should be easily removable at the end of the reaction sequence. N-deprotection may be effected by conventional methods, for example an alkoxycarbonyl group such as t-butoxycarbonyl may be cleaved by hydrolysis and an aralkyloxycarbonyl group such as benzyloxycarbonyl or an aralkyl group such as benzyl may be cleaved by hydrogenolysis.

P30566 Div AU Cyclisation with 4-carboxamidophenylhydrazine or a salt thereof is preferably carried out with a ketal of formula however if desired the ketal may be converted to the corresponding ketone prior to this reaction.

Yet a further method for preparing an enantiomeric mixture of formula (I) comprises reacting a compound of formula (IV)

H

2 NCOO N Z

H

Formula (IV) wherein Z is a leaving group, such as a halogen atom or a sulphonyloxy (e.g.

p-toluenesulphonyloxy or methanesulphonyloxy) group with an amine H 2

NR

1 or a derivative thereof. Said derivative may optionally contain a chiral centre, as in for example -methylbenzylamine, resulting in a diastereoisomeric mixture of the corresponding derivative of formula The diastereoisomers may be separated by chromatography, followed by hydrogenolysis to give the desired enantiomer of formula An enantiomeric mixture of 3-amino-6-carboxamido- 1, 2 ,3,4-tetrahydrocarbazole may be prepared in an analogous manner to formula using 4 -aminocyclohexanone, optionally protected as a ketal derivative, or an N-protected phthalimido) derivative thereof. The enantiomers of 3-amino-6-carboxamido-1,2,3,4-tetrahydrocarbazole may be resolved by chiral HPLC as described for process above, using a derivative such as of 3 -t-butyloxycarbonylamino-6-carboxamido-1,2,3,4-tetrahydrocarbazole; or by formation of a chiral salt of the 3-amino compound in a similar manner to process above, using for example 2 3 4 6 -di-O-isopropylidene-2-keto-L-gulonic acid, followed by selective crystallisation. Such methods are described in International Application W093/00086.

Enantiomers of formula have been found to be agonists and partial agonists at 5-HTI-like receptors. Nomenclature of 5-HT receptors is constantly evolving. At least four subtypes of the 5-HT 1 receptor family have been described, namely 5-HTla, 5-HT1b, 5-HT1c and 5-HTld. Functional contractile 5-HT -like receptors have been identified in the dog saphenous vein and in cerebral (basilar) arteries of various species including rabbit and human. It is now believed that the functional 5-HT 1 -like receptor correlates with the 5-HT1d binding site A Parsons, TIPS, Aug 1991, Vol 12).

Enantiomers of formula are expected to have utility in the treatment and/or prophylaxis of migraine, with and without aura, tension headache, cluster headache and othe forms of cephalic pain and trigeminal neuralgias.

The invention therefore further provides the use of an enantiomer of formula (I) or a physiologically acceptable salt thereof in the manufacture of a medicament for the P:\OPER\PDB\2851797.138 19/5199 treatment of a condition where a 5-Htl-like agonist is indicated, in particular the treatment or prophylaxis of migraine.

The invention also provides a method of treatment of a condition wherein a 5-HT 1 -like agonist is indicated, in particular migraine, which comprises administering to a subject in need thereof an effective amount of an enantiomer of formula or a physiologically acceptable salt thereof.

The invention also provides use of a compound as defined in any one of claims 1 to 4 for the manufacture of a medicament for the treatment of a conditions where a 5-HT 1 -like agonist is indicated.

For use in medicine, a compound of the present invention will usually be administered as a standard pharmaceutical composition. The present invention therefore provides in a further aspect pharmaceutical compositions comprising an enantiomer of formula or a physiologically acceptable salt thereof and a physiologically acceptable carrier.

The compounds of formula may be administered by any convenient method, for example by oral, parenteral, buccal, sublingual, nasal, rectal or transdermal administration and the pharmaceutical compositions adapted accordingly.

•The compounds of formula and their physiologically acceptable salts which are 20 active when given orally can be formulated as liquids or solids, for example syrups, go suspensions or emulsions, tablets, capsules and lozenges.

A liquid formulation will generally consist of a suspension or solution of the compound or physiologically acceptable salt in a suitable liquid carrier(s) for example an aqueous solvent such as water, ethanol or glycerine, or a non-aqueous solvent, such as S 25 polyethylene glycol or an oil. The formulation may also contain a suspending agent, preservative, flavouring or colouring agent.

A composition in the form of a tablet can be prepared using any suitable pharmaceutical carrier(s) routinely used for preparing solid formulations. Examples of such carriers include magnesium stearate, starch, lactose, sucrose and cellulose.

3 0 A composition in the form of a capsule can be prepared using routine encapsulation P:AOPER\PDB\2517-97.138 19/5/99 procedures. For example, pellets containing the active ingredient can be prepared using standard carriers and then filled into a hard gelatin capsule: alternatively, a dispersion or suspension can be prepared using any suitable pharmaceutical carrier(s), for example aqueous gums, celluloses, silicates or oils and the dispersion or suspension then filled into a soft gelatin capsule.

Typical parenteral compositions consist of a solution or suspension of the compound or physiologically acceptable salt in a sterile aqueous carrier or parenterally acceptable oil, for example polyethylene glycol, polyvinyl pyrrolidone, lecithin, arachis oil or sesame oil.

Alternatively, the solution can be lyophilised and then reconstituted with a suitable solvent just prior to administration.

Compositions for nasal administration may conveniently be formulated as aerosols, drops, gels and powders. Aerosol formulations typically comprise a solution or 9* e 0 9 0 9* 9 o* P30566 Div AU fine suspension of the active substance in a physiologically acceptable aqueous or nonaqueous solvent and are usually presented in single or multidose quantities in sterile form in a sealed container, which can take the form of a cartridge or refill for use with an atomising device. Alternatively the sealed container may be a unitary dispensing device such as a single dose nasal inhaler or an aerosol dispenser fitted with a metering valve which is intended for disposal once the contents of the container have been exhausted.

Where the dosage form comprises an aerosol dispenser, it will contain a propellant which can be a compressed gas such as compressed air or an organic propellant such as a fluorochlorohydrocarbon. The aerosol dosage forms can also take the form of a pump-atomiser.

Compositions suitable for buccal or sublingual administration include tablets, lozenges and pastilles, wherein the active ingredient is formulated with a carrier such as sugar and acacia, tragacanth, or gelatin and glycerin.

Compositions for rectal administration are conveniently in the form of suppositories containing a conventional suppository base such as cocoa butter.

Compositions suitable for transdermal administration include ointments, gels and patches.

Preferably the composition is in unit dose form such as a tablet, capsule or ampoule.

Each dosage unit for oral administration contains preferably from 1 to 250 mg (and for parenteral administration contains preferably from 0.1 to 25 mg) of a compound of the formula or a physiologically acceptable salt thereof calculated as the free base.

The physiologically acceptable compounds of the invention will normally be administered in a daily dosage regimen (for an adult patient) of, for example, an oral dose of between 1 mg and 500 mg, preferably between 10 mg and 400 mg, e.g. between 10 and 250 mg or an intravenous, subcutaneous, or intramuscular dose of between 0.1 mg and 100 mg, preferably between 0.1 mg and 50 mg, e.g. between 1 and 25 mg of the compound of the formula or a physiologically acceptable salt thereof calculated as the free base, the compound being administered 1 to 4 times per day. Suitably the compounds will be administered for a period of continuous therapy, for example for a week or more.

BIOLOGICAL TEST METHODS 5-HT 1 -like Receptor Screen RABBIT BASILAR ARTERY Experiments were performed in intracranial arteries from rabbit isolated basilar artery in a similar method to that described previously (Parsons and Whalley, 1989. Eur J Pharmacol 174, 189-196.).

-8- P30566 Div AU In brief, rabbits were killed by overdose with anaesthetic (sodium pentobarbitone). The whole brain was quickly removed and immersed in ice cold modified Kreb's solution and the basilar artery removed with the aid of a dissecting microscope. The Krebs solution was of the following composition (mM) Na+ (120); K+ Ca 2 Mg 2 Cl- SO2- EDTA equilibrated with 02/5% CO 2 The endothelium was removed by a gentle rubbing of the lumen with a fine metal wire. Arteries were then cut into ring segments (ca 4-5 mm wide) and set up for recording of isometric tension in 50 ml tissue baths in modified Krebs solution with the additional supplement of Na 2 fumarate pyruvate L-glutamate and glucose The arteries were then placed under a resting force of 3-4 mN maintained at 37°C and the solution bubbled with 95% 02/5% CO 2 After tests for initial reactivity with 90 mM KC1 depolarising solution and for lack of acetylcholine-induced relaxation of 5-HT (10 mM) precontraction, cumulative concentration-effect curves (2 nM-60 mM) to 5-HT were constructed in the presence of ascorbate 200 mM, cocaine 6 mM, indomethacin 2.8 mM, ketanserin 1 mM and prazosin 1 mM.

Following a 45-60 min wash period, cumulative concentration-effect curves to the test compounds or 5-HT (as a time match control) were constructed in the presence of ascorbate, indomethacin, cocaine, ketanserin and prazosin.

Test Compounds R-(+)-6-carboxamido-3-N-ethylamino- 1,2,3,4-tetrahydrocarbazole; (compound C) S-(-)-6-carboxamido-3-N-ethylamino-1,2,3,4-tetrahydrocarbazole. (compound D) Results Compound C 0.16 pM Compound D 2.1 pM 0 Pharmaceutical Formulations The following represent typical pharmaceutical formulations according to the present invention, which may be prepared using standard methods.

IV Infusion Compound of formula 1-40 mg Buffer to pH ca 7 Solvent/complexing agent to 100 ml Bolus Injection Compound of formula 1-40 mg Buffer to pH ca 7 -9- P30566 Div AU Co-Solvent to 5 ml Buffer: Suitable buffers include citrate, phosphate, sodium hydroxide/hydrochloric acid.

Solvent Typically water but may also include cyclodextrins (1-100 mg) and co-solvents such as propylene glycol, polyethylene glycol and alcohol.

Tablet Compound Diluent/Filler Binder Disentegrant Lubricant Cyclodextrin 1 40 mg 50 250 mg 5 25 mg 5 50 mg 1 5 mg 1 100 mg may also include cyclodextrins Diluent Binder: Disintegrant: Lubricant: e.g. Microcrystalline cellulose, lactose, starch e.g. Polyvinylpyrrolidone, hydroxypropymethylcellulose e.g. Sodium starch glycollate, crospovidone e.g. Magnesium stearate, sodium stearyl fumarate.

S..

S.

55

S

S.

P30566 Div AU Oral Suspension Compound Suspending Agent Diluent Preservative Buffer Co-solvent Flavour Colourant 1 40 mg 0.1 10 mg 20 60 mg 0.01 1.0 mg to pH ca 5 8 0 40 mg 0.01 1.0 mg 0.001 0.1 mg

S

*5* Suspending agent: e.g. Xanthan gum, microcrystalline cellulose Diluent: e.g. sorbitol solution, typically water Preservative e.g. sodium benzoate Buffer e.g. citrate Co-solvent: e.g. alcohol, propylene glycol, polyethylene glycol, cyclodextrin Preparation 1 (±)-3-Amino-6-carboxamido- ,2,3,4-tetrahydrocarbazole 20 4-Carboxamidophenylhydrazine hydrochloride (2.87 g) and 4-phthalimidocyclohexanone (3.00 g) were mixed in acetic acid and the mixture was heated under reflux for 2 hr. After cooling, the mixture was neutralized using aq.

potassium carbonate solution, and the yellow solid thus obtained was filtered, washed with water, and dried. Purification by column chromatography (SiO 2 CHC1 3

/CH

3 0H) gave 6- 25 carboxamido-3-phthalimido-l,2,3,4-tetrahydrocarbazole (2.8 g).

The above product (1.0 g) was suspended in ethanol (10 ml) and hydrazine hydrate (5 ml) was added. A clear solution was obtained, and the mixture was left to stir overnight, to yield a precipitate. The whole mixture was evaporated to dryness, washed with aq. K 2

CO

3 solution, and water, to leave the title compound 3-amino-6-carboxamido-1,2,3,4-tetrahydrocarbazole (0.44 as the monohydrate, mp.

146-148 0

C.

1 H NMR [250 MHz, DMSO-d 6 1.49-1.77 1.83-2.03 2.17-2.40 (1H,m), 2.62-2.80 2.90 (1H,dd), I signal obscured by H 2 0 at ca. 3.1, 7.03 (1H,brd.s), 7.18 7.58 7.83 (1H,brd.s), 7.98 (1H,s).

-11- P30566 Div AU Preparation 2 and 3-A mino-6-carboxamido- 1 ,2,3,4-tetrahydrocarbazole hydrochloride Method 1 (±)-3-t-Butyloxycarbonylanino-6-carboxamido-1,2,3,4-tetrahydrocarbazole was separated into its enantiomers using chiral HPLC: (chiralcel OD 4.6 mm column, eluting with hexane/ethanol 85:15). The (+)-enantiomer was collected first and had mp 150-152 0 C and +70.1 (in methanol, 0.41% The (-)-enantiomer had mp 25 150-152 0 C and -79.4 (in methanol, 0.40% The (+)-enantiomer was converted to the parent amine hydrochloride by treating with HC1 gas in dioxane, to furnish the (+)-enantiomer of 3-amino-6-carboxamido-1,2,3,4-tetrahydrocarbazole hydrochloride, np 248-251 0 C, +26.2 (in methanol, 0.50% The (-)-enantiomer of 3-t-butyloxycarbonylamiino-6-carboxamido- 1,2,3,4-tetrahydrocarbazole was similarly converted into the (-)-enantiomer of 3-amino-6-carboxamido-1,2,3,4tetrahydrocarbazole hydrochloride, mp 248-251 0 C, [a]D -28.6 (in methanol, 0.50% w/v).

Method 2 (±)-3-amino-6-carboxamido-1,2,3,4-tetrahydrocarbazole was treated with one Sequivalent of 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid in methanol to give the 20 salt of the (+)-enantiomer, in 38% yield (with respect to racemate) and 84% enantiomeric excess This material was recrystallized twice from methanol to give the salt of the (+)-enantiomer in 25% overall yield (with respect to racemate), and >98% ee. This product was converted to the hydrochloride salt first by treatment with aqueous alkali, and the precipitated free base treated with 2M aq. HCI in ethanol, to give 3-amino-6carboxamido-1,2,3,4-te trahydrocar-bazole hydrochloride.

Preparation 3 (±)-6-Carboxamido-3-N-imethylaiino-1,2,3,4-tetrahydrocarbazole hydrochloride 4-Cyanophenyl hydrazine hydrochloride (20.2 g) and 4-benzoyloxy- 30 cyclohexanone (25.9 g) were dissolved in glacial acetic acid (400 ml) and the mixture was heated under reflux for 1.5 hr. After allowing to cool, the mixture was filtered, and the filtrate was evaporated to dryness, and neutralized with aqueous sodium bicarbonate solution to give a solid precipitate, which was purified by chromatography (SiO 2 hexane/ethyl acetate) to give 3-benzoyloxy-6-cyano-1,2,3,4-tetrahydrocarbazole (18 g).

This product (11.6 g) was suspended in ethanol (230 ml) and treated with 2.5% aqueous potassium hydroxide solution (120 ml), and heated under retlux for 1 hr. The cooled -12- P30566 Div AU mixture was neutralized with glacial acetic acid and evaporated to a solid residue, which was washed with water, and dried to give 3 -hydroxy- 6 -cyano-l,2,3,4-tetrahydrocarbazole (6.6 g).

The above product (3.57 g) was dissolved in dry pyridine (35 ml) and treated with tosyl chloride (3.51 g) in dry pyridine (35 ml), and the mixture was stirred at 100 0 C for 2 hr. After cooling, the solution was poured into water (500 ml), extracted with ethyl acetate, and the latter extract was washed with 2M HC1, dried (MgSO 4 and evaporated to dryness. Purification by chromatography (SiO 2 hexane/ethyl acetate) gave 3-tosyloxy- 6-cyano-l, 2 ,3,4-tetrahydrocarbazole (0.53 g).

This product (0.40 g) was dissolved in 33% methylamine in alcohol (25 ml) and heated at 100°C in a sealed steel vessel for 1.5 hr. After cooling, the mixture was evaporated to dryness and purified by chromatography (SiO 2 chloroform/methanol) to give 3-methylamino-6-cyano- 1,2,3,4-tetrahydrocarbazole (0.13 g).

The above product (0.12 g) was dissolved in THF (10 ml) and reacted with di-tert-butyl dicarbonate (0.36 g) in THF (3 ml) at room temperature overnight. The reaction mixture was evaporated to dryness, partitioned between 2M sodium bicarbonate solution and ethyl acetate, and the organic extract dried and evaporated to give a white solid. This was triturated with ether/hexane to give 3 -t-butyloxycarbonylmethylamino- 6-cyano-1,2,3,4-tetrahydrocarbazole (0.14 g).

20 This product (0.14 g) was dissolved in methanol (15 ml) and treated with a mixture of 20% aqueous sodium hydroxide (0.20 ml) and 30% hydrogen peroxide (0.20 ml), and the whole mixture was stirred at room temperature overnight. Sodium metabisulphite (38 mg) was added, and the solution was evaporated to dryness, and chromatographed (Si02; chloroform/10% NH 4 0H in methanol) to give 3-methylamino- 6 -carboxamido-1,2,3,4-tetrahydrocarbazole (0.12 The above compound (0.11 g) was dissolved in methanol (10 ml), and treated with 3M hydrochloric acid at room temperature. The mixture was evaporated to dryness, azcotroping with ethanol to give a solid, which was recrystallized from methanol/cther to give the title compound, mp 327- 328 0 C (80 mg).

30 1H NMR [250 MHz, MeOH-d 4 d 1.98-2.20 (1H, 2.29-2.49 (1H, 2.75-2.90 (5H, s 2.90-3.09 (2H, 3.52-3.69 (1H, 7.31 (1H, 7.63 (IH, 8.05 (1H, s).

Preparation 4 (±)-6-Carboxamido-3-N-ethylamino-1,2,3,4-tetrahydrocarbazole oxalate 1,4-Cyclohexanedione mono-2',2'-dimethyl trimethylene ketal (2.00 g) was mixed with anhydrous ethylamine (10.0 g) and benzene (10 ml), and the mixture was cooled to A solution of titanium tetrachloride (0.95 g) in benzene (10 ml) was added, dropwise, then the mixture was stirred at room temperature for 1 hr. The mixture was -13- P30566 Div AU filtered, and evaporated to dryness to give an oil, which was dissolved in ethanol (30 ml).

To this solution was added palladium-on-carbon catalyst (100 mg), and the mixture was hydrogenated at 50 psi pressure overnight. The catalyst was filtered off and the ethanol evaporated to leave 4 -ethylamino-cyclohexanone 2',2'-dimethyl trimethylene ketal as an oil (2.0 g).

This compound (0.80 g) was dissolved in formic acid (20 ml) and the solution was heated to 90 0 C for 1 hr. Formic acid was evaporated, and the residue was partitioned between chloroform and 1M hydrochloric acid. The aqueous layer was evaporated to dryness to give 4 -ethylaminocyclohexanone (0.40 g).

A mixture of the above product (0.40 g) and 4-carboxamidophenyl hydrazine hydrochloride (0.60 g) in glacial acetic acid (20 ml) was heated under reflux for 1 hr. The acid was evaporated in vacuo to an oil, which was purified by chromatography (SiO 2 CHCl 3 /10% NH 3 in MeOH) to give an oil (0.50 Part of this product (150 mg) was dissolved in methanol and treated with oxalic acid. The solution was treated with ether to give the title compound as a crystalline solid, mp 165-170°C (100 mg).

1H NMR [250 MHz, DMSO-d 6 J] 1.25 (3H, 1.81-2.05 (1H, 2.20-2.38 (1H, m), 2.61-2.79 (1H, 2.79-2.94 (2H, 2.98-3.28 (3H, dd 3.41-3.60 (1H, 7.08 (1H, brd. 7.28 (1H, 7.60 (1H, 7.82 (1H, brd. 8.00 (1H, 11.12 (1H, s).

20 Preparation (+)-6-Carboxamido-3-N-methylamino-1, 2 ,3,4-tetrahydrocarbazole A solution of (±)-6-carboxamido-3-N-methylamino- 1,2,3,4-tetrahydrocarbazole hydrochloride salt (6.0g) in water (60 ml) at 68°C was basified to pH 10.5 with aqueous sodium hydroxide. The resultant mixture was extracted with butan-1-ol (30 ml, 25 15 ml). These extracts were combined and evaporated to give the title compound as a dark oil (6.96g) containing ca. 46% w/w butan-1-ol.

1H NMR[400MHz, d 6 -DMSO]8 1.40-2.00 (1H,br), 1.62 2.06 2.33 (1H,m) 2.39 2.77 2.97 (1H,dd), 7.02 7.24 7.59 (1H,dd), 7.80 7.99 10.93 (1H,s) peaks due to butan-1-ol.

Preparation 6 4 -Methylaminocyclohexanone (2',2'-dimethyltrimethylene) ketal hydrochloride 1, 4 -Cyclohexanedione (mono- 2 '2'-dimethyltrimethylene) ketal (50g) was dissolved in dry toluene (500ml) in a flask fitted with a dry ice trap and flushed with nitrogen with stirring. Methylamine (47.0g) was then added dropwise to the reaction mixture, at 20 0 C slowly to allow dissolution in the toluene. Molecular sieves (32.0g) were then added and the reaction mixture stirred at 20°C under an air lock. The reaction was -14- P30566 Div AU complete after ca. 4h The sieves were then filtered off and the clear amber filtrate evaporated to a volume of 160ml. The concentrated solution of iminoketal was diluted with ethanol (340ml) and degassed with argon. Palladium catalyst (palladium on charcoal, 3.55g) was added and the mixture hydrogenated at atmospheric pressure and 20°C for 24h. When hydrogen uptake was complete the reaction mixture was filtered through Celite and the Celite bed washed with a little ethanol (2 x 25ml). The solvent was then removed under reduced pressure to give the ketal amine as an amber oil. (49.12g, 92%).

The ketal amine (80g, 0.375Mol) was dissolved in isopropyl ether with stirring. A solution of HC1 in isopropyl ether (prepared by bubbling a known weight of gas into a known volume of solvent) was added dropwise causing the formation of an immediate white precipitate, which became very thick as the addition was completed. The thick suspension was stirred for a further 30 minutes, filtered off, and the product washed with a little fresh isopropyl ether and then dried under vacuum to give the title compound as a white, free flowing powder (84.01g).

1H NMR: -[270MHz, CDC1 3 18 9.51 (2H,bs), 3.48 3.00 2.73 2.32 2.15 1.85, (2H,dq), 1.41 (2H,dt), 0.96 (6H,s).

Preparation 7 20 (±)-6-Carboxamide-3-methylamino-1,2,3,4-tetrahydrocarbazole hydrochloride i 4-Aminobenzamide (3.0g) was dissolved in 5N HCI (20m1) cooled to -5 to 0 C with stirring and the mixture further cooled to around -15 0 C. Sodium nitrite (1.98g) in water (4.4ml) was added dropwise with stirring at such a rate that the temperature was maintained at between -10 to -15 0 C. The mixture was then stirred at around -8 0 C for 25 30min. Ice cold water (40ml) was then added followed by solid sodium dithionite (7.7g) in a single portion, the means of cooling removed and the mixture stirred at around 15 0 C for To the resulting yellow suspension was added conc. HC1 (30ml) followed by 4methylaminocyclohexanone (2'2'-dimethyltrimethylene) ketal hydrochloride (5.488g) and the mixture heated to around 70°C, not allowing the reaction temperature to rise above 75°C. After ca. 2h, the reaction mixture was cooled to 20 0 C and the dark solution then carefully neutralised with caustic 40%) to pH 10 maintaining the temperature between 15 20°C, whereupon a thick precipitate formed to give the title compound. The reaction mixture was then left to stir overnight and the precipitate filtered off and dried (3.88g, 63%).

1H nmr [250MHz, d 6 DMSO]6 =11.21 8.06 7.89 (1H,bs), 7.63 7.28 7.10 (1H,bs), 3.50-3.15 2.95-2.70 2.62 2.33 1.97 (1H,m).

P30566 Div AIJ Preparation 8 4-Methylaminocyclohexanone -di methyl trimethylene) ketal hydrochloride 1 ,4-Cyclohexancdione mono-2,2-dimethyltrimethylenc ketal (20.0g, 0.101 mol) was dissolved in ethanol (200 ml) containing methylamine 0.258 mol). The S resultant solution was hydrogenated at 30 psi over 10% Pd/C catalyst (2.0Og) for 4 hrs at room temperature. The reaction mixture was filtered through a celite pad and the filtrate evaporated under reduced pressure to give an oil (21.4g).

The oil was dissolved in tetrahydrofuran (210 ml) and the resultant solution cooled in an ice/water bath while conc.HCl (10.5 ml) was added to the stirred solution in two portions such that the temperature did not rise above 15'C and then filtered. The solid was washed with THF (50 ml) and air dried overnight to give the title compound (22.80g). mp 245. 1 T (EtOH).

IHnmr (250MHz, d 6 DMSO)8 0.9 (s,614), l.3(q,2H), 1.45 1.9 (brd,2H), 2.25 (brd,2H), 2.5 (s,314), 3.0 IH), 3.5 (d,4H).

Preparation 9 and -C arboxani do- 3-N- methyl ami no- 1 tetra hyd roca rbazole hydrochloride To a stirred solution of (±)-6-carboxaimido-3-N-methylamino-1,2,3,4- 20 tetrahydrocarbazole hydrochloride 3g) in propan-2-o1'saturated aqueous potassium hydrogen carbonate (20:1 2lrnl), di-tert-butyl dicarbonate (0.425g) was added and stirring continued for I hour. The mixture was diluted with ethyl acetate (50m1) washed with *water (2x20m1), dried (Mgc-SO 4 and solvent removed at reduced pressure to g'ive 3-Ntert-buitoxycarbonyl-N-methylamiino-6-car-boxamiido-1 I 2,3 tetra hydrocarb azole (0.36g).

IH NMR (d 6 -DMSO) 5 l.47(s,9H), 1.84-2.08(m,21-), 2.7 l-2.94(ml,4H-), 2.80(s,3H), 4,26(m,1H), 7.02(br.s,lH), 7.25(d,1H), 7.57(d,1H), 7.76(br.s,1H), 7.97(s,1H) and 10.96(s, 1H).

The W+ and the enantiomers of (±)-3-N-tert-butoxycarbonyl-Nmethylamino-6-car-boxamiido- 1,2,3 ,4-tetrahydr-ocarbazole (0.3g) were separated by chiral HPLC: (chiralpak AD 20mm column, hexane:ethanol 9:1 eluant), Treatment of the first elutino enantiomer (0.022) with 3N aqueous hydrochloric acid/methanol 1:1 (4m1l) forl6 hours, filtration and removal of solvent gave, after recrystallisation from methanol/diethyl ether, the enantiomer of the title compound (0.009g) m.p. 219-225TC, [uX]25C= +25.4 (methanol 0.063% w/v).

Treatment of the second eluting enantio mer (0.03g0 under similar conditions gave the enantiomer of the title compound (0.02g), imp. 219-225TC 23.3 (methanol 0.1. 16%w/v).

16- P30566 Div AU Preparation (+)-6-Carboxamido-3-N-methylanmino- 1,2,3,4-tetrahydrocarbazole To a solution of (±)-6-carboxamiido-3-N-methylam-iino-1,2,3,4tetrahydrocarbazole (0.77a) in dimethylformamide (7Ornl), triethylamine (0.62g) and benzyl chioroformate (0.47g) were added. The solution was stirred overnight, further triethylamine (0.27g) and benzyl chioroformate (0.26g) added and the mixture stirred for 4 hours. The reaction mixture was poured into water (5O0m and extracted with ethyl acetate (2 x 50mi). The combined extracts were dried (MgSO 4 and solvent was removed at reduced pressure. The residue was recrystallised from methanol/water to give benzyloxycarbonyl-6-carboxamido-3-N-methylamino- 1,2,3 ,4-tetrahydrocarbazole (0.64g) m.p. 103-1 10 0

C.

The and enantiomers of (±)-3-N-benzyloxycarhony]-6carboxamido-3-N-miethylamiino- 1,2,3,4-tetr-ahydrocar-bazole were separated by chiral HPLC (OD colum n, eluant hexane/ethanol 4: 1).

The first eluting enantiorncr mn.p. 105-106'C, r(I 157.2. (ethanol, 0.39%w/v).

The second eluting enantiomner (0.23gy) m.p. 105-106 0 C, I~ (X 163.1 (ethanol, 0.23%w/v).

A solution of (+)-3-N-benizyloxycarbonyl-6-carboxamido-3-Nmethylamino- 1,2,3,4-tetr-ahydrocarbazole (0.23g) in ethanol (20m1) containing palladium/charcoal (0.23g) was shaken under a hydrogen atmosphere (50psi) for 3 hours.

:Catalyst was removed by filtration and solvent removed at reduced pressure to give the enatioerof the title compound (free base)as a foam m.p. 98-102'C.o +1.2 Preparation 11 Carboxa mido-3- N-methyl amino- 1 tetrahyclrocarbazole camphorsulphonate To a solution of (±)-6-car-boxamido-3-N-methylamino- 1,2,3,4tetrahydrocarbazole (3g) in methanol a solution of acid (2.86g) in methanol was added. Solvent was removed at reduced pressure and the residue recrystallised ten times to give the enantiomner of the title compound as the camphorsulphonate salt mn.p. 177- 180 0 C. This was treated with 2 equivalents of triethylamine and 10 equivalents of 2,3,4,6-tetra-o-acetyl-beta-D-glIucopyranosylisothiocyanate in dimethylformamide at room temperature for 30 minutes. Aliquots of the reaction mixture wre removed from the mixtue for HPLC analysis. Analytical HPLC of the 2,3,4,6- tetra-0- acetyl-beta -D-gl ucopyran osylth i ou re a derivative (C 18 Novapak, eluant 17 P30566 Div AU methanol! 50mMNaH 2

PO

4 pH 2.9) gave the same retention time as the the same derivative prepared from the enantiomer of Example 1 and showed the material was 99% ee.

Preparation 12 (+)-6-Carboxamido-3-N-methylamino- 1,2,3,4-tetrahydrocarbazole succinate (1:1) Benzaldehyde (I10.6g) was added to a suspension of (+)-3-amino-6carboxamido- 1,2,3 ,4-tetrahydrocarbazole (1 2.35gy) in methanol (1 O0ml).The mixture was stirred for 1 hour, sodium cyanoborohydride (9.3g) added over 1 hour and the clear solution stirred for 24 hours. The solution was cooled (ice bath) and fornaldehyde (37% aqueous methanolic, 9:1 solution, 5.5m1) added. After 30 minutes stirring at room temperature water (lO0mi) was added, stirring continued for 30 minutes followed by extraction with dichioromnethane (3x I The combined organic extracts were washed with water (2x200m1l), dried (Na 2

SO

4 filtered and solvent removed at reduced pressure.

The residue was column chromatographed (silica gel, ethanol/dichioromethane) to give 3 -N -ben zyl -6-c arboxam ido- 3-N-methylam ino- 1,2,3,4tetrahydrocarbazole (9.4g) as a foam. The succinate salt 1) was recrystallised from methanol m.p. 175-182'C 1H NMR (d 6 -DMSO)8 1.81-1 .96(m, lH), 2.09-2.21 (m,1 2.29(s,3H), 2.44(s,4H), 2.66- 3.1l 3.76(q,2H), 7.05(br. s IH), 7.22-7.43(mi,6H), 7.59(d, IH), 7.79(br. s, 1H), 8.03(s,1H), and 10.94(s,1H).

To a solution of 3-N-benzyl-6-carboxamido-3-N-methylamino- 1,2,3,4- :tetrahydrocarbazole in ethanol (lO0nmI) containing succinic acid (0.39g), Pearimans catalyst was added and the mixture shaken under an atmosphere of hydrogen at psi and 50'C for 2 hours. The mixture was filtered (celite pad) and the pad washed thoroughly with ethanol. The combined filtrate and washings were evaporated to dryness, co-evaporated with ethanol (3x I 00ml) and recrystallised from methanol to give the title compound 1) succinate salt]. mn.p. 148-155'C.

H NMR (d 6 -DMS0) 6 1. 84(n, I 2.15 -2.3 4(mi,I1H), 2.2 8(s,41H), 2.57 (11,l1H), 2.61(s,3H), 2.83(m,2H), 3.13(dd,lH), 3.29(m,IH), 7.08(hr s,IH), 7.26(d,1H), 7.60(dd,1H), 7.82(br s,1H), 8.01 (d,l H) and II .08(s,1H).

Preparation 13 (+)-6-Carboxamiido-3-N-inethylai-nino- 1,2,3,4-tetrahydrocarbazole To a solution of (+)-3-am-ino-6-carboxanmido-1,2,3,4tetrahydrocarbazole (5gI) in pyridine (I150rn1), dicyclohexylcarbodiim-ide (4.13g) was added followed by carbon disulphide (I .67gr). The solution was stirred for 1 hour, solvent 18 P30566 Div AIJ removed at reduced pressure and the residue co-evaporated with toluene (3x100m1). The residue was recrystallised from methanol to give 6-carboxamido-3 -isothiocyanato- 1,2,3,4tetrahydrocarbazole (5.06g) m.p.245-248 0

C.

A solution of 6-carboxamido-3-isothiocyanato- 1,2,3,4-tetrahydrocarbazole (0.25-g) in ethanol (40m1) was treated with sodium borohydride (0.17g) in one portion and stirred for 18 hours. Acetone (5m1) was added the mixture stirred for a further 1 hour and solvent removed at reduced pressure. The residue was column chrom atographed (basic alumina, 5% methanol/dichioromethane eluant) to give the title compound 1 lg) having the same physico chemical characteristics as the product of Preparation Example 1 and 6-Ca rboxa mido- 3- N-ethyl anii no- I tetra hyd roca rbazol e hydrochloride From (±)-6-car-boxam-ido-3-N-ethylamino- 1,2,3 ,4-tetrahydrocarbazole (0.26g0, -N-tcrt butoxycarbonyl-N-ethylamino-6-carboxamido- 1,2,3,4-tetrahydrocarbazole (0.270) isolated as an oil was prepared according to the procedure of Preparation 9.

1 H NMR (d 6 -DMSO) 6 1.1(t,314), i.23(s,9H), l.92(m,JH), 2.09(in,1), 2.78-2.92(m,4H), 3.21-3.62(m,2H), 4.21 (m,lIH), 7.04(br.s,1IH), 7.24(d,1IH), 7.58(d, ILH), 7.76(br.s,1IH), 7.99(s,1H) and 10.99(s,iH).

From (±)-3-N-tert butoxycarbonyl-3-N-ethylamiino- 1,2,3,4-tetrahydro- :carbazole (0.25g), the and the enantiomers of 3-N-tert butoxycarbonyl-3-Nethyl am ino- 1, 2,3,4- tetrahydrocarh azol e were prepared by chiral HPLC (chiralcel OD 4.67mm, eluant hexane/ethanol 92/8).

Treatment of the enantiomner eluting first, (0.06a) [a]c 5' +108.2 (ethanol 0.9%w/v) with hydrochloric acid/mnethanol according to the method of Preparation 9 gave (+)-6-carboxa iid o-N-eth yl ami no- 1,2,3,4- tetra by droca rbazol e hydrochloride (0.04g) 211-22]'~C [oX]25C +37.2 (methanol, 0.12%w/v).

Treatment of the second clutino enantiomer (80mg) [a 13. etanl 0.19%w/v) with hydrochloric acid/methanol according to the method of Preparation 9 gave (-)-6-carboxamido-3-N-ethylamino- 1,2,3,4-tetrahydrocarbazole hydrochloride m.p. 21 1-221'C after recrystallisation from methanolldiethyl ether -33.6 (methanol, 0.11 19- P30566 Div AU Example 2 (+)-6-Car-boxaimido-3-N-ethliniio- 1,2,3,4-tetr-alydi'ocar-bazole succinate (1:1) From (+)-3-ainoii--6-cariboxamiiido- I ,2,3,4-tetrahiydrocarbazolc (+)-3-N-benizyl-N-ethiylamiiino-6-cariboxamiido- 1,2,3,4-tetr-ahydr-ocaribazole was obtained according to the procedure of Preparation 12 replacing formaldehyde with acetaldehyde The succinate salt 1) was prepared by addition of sticcinic acid to the free base (1.0og) and recrystallisation fromi propan-2-oI mi.p. 130-140'C.

IH NMR (d 6 -IDMS() 6 1 .05(t,3H), I .85(mnj 2. 1 (m,l 2.40(s,41 2.58- 2.9 t1(m, 5H), 3.0 6 3.7 7(cl, 2H), 7.0 3(b r.s, I 7.17 7-7.47 (11,5 7.5 8(d,1IH), 7.78(br.s,1IH), 8.00(s,1I 10.90(s, I H) and 12.28(br.s2H).

Recrystallisation of (±)-3-N-henizyl-N-ethiylainiio-6-cartlboxamiido- 1,2,3,4-tetrahtlydr-ocar-bazole succiniate (1 fromi methanol, according to the procedure of Preparation 12 cave the title compound (1 .04g)) mI.p. 165-1 67C.

1H NMR (d6-DMSO) 8 1.1 9(t,3H), I .86(m,1 2.23(mi,ff), 2.30(s,4H), 2.62(mlH), 2.85(rn,214), 3.02(cj,2H-), 3. 14(ni,IH), 3.38(ni,I1-1), '7.08(br.s,11H), 7.26(d, lH), 7.59(d,1H), 7.80(br.s, I 8.OQ)(s,.i H) and I1. 08(s, I H).

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "Comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (16)

1. A enantiomer of a compound of formula O H 2 NC NHR H Formula (I) wherein R' is ethyl, or a salt, solvate or hydrate thereof, substantially free from the corresponding enantiomer.

2. (+)-6-Carboxamido-3-ethylamino-1,2,3,4-tetrahydrocarbazole or a salt, solvate or hydrate thereof, substantially free from the corresponding enantiomer.

3. (+)-6-Carboxamido-3-ethylamino- ,2,3,4-tetrahydrocarbazole succinate (1.1) or a solvate or hydrate thereof, substantially free from the corresponding enantiomer. S*

4. (+)-6-Carboxamido-3-ethylamino-1,2,3,4-tetrahydrocarbazole hydrochloride, 20 solvate or hydrate thereof, substantially free from the corresponding enantiomer.

A process for preparing an enantiomer of formula as defined in either of claim 1 or claim 2 or a salt, solvate or hydrate thereof which comprises: separation of an enantiomeric mixture of a compound of formula or a 25 derivative thereof by chromatography; or separation of diastereoisomers of chiral derivative of a compound of formula or ethylation of the enantiomer of 3-amino-6-carboxamido-1,2,3,4- tetrahydrocarbazole or a salt thereof, 30 followed if necessary or desired by removal of any N-protecting group or facilitating group, P' RA/ P:\OPER\PDB\28517-97.137 17/5/99 conversion of a salt into a free base and/or salt formation.

6. A process according to claim 5 wherein separation of an enantiomer mixture of a compound of formula is facilitated by introducing a readily removable group into the ethylamino moiety of formula

7. A process according to either of claims 5 or 6 wherein separation is effected on a chiral HPLC column.

8. A process according to claim 5 wherein a chiral derivative is obtained by reaction of the compound of formula with R-2-pyrrolidine-5-carboxylic acid.

9. A process according to claim 8 wherein the diasteroisomeric salts formed by reaction with R-2-pyrrolidine-5-carboxylic acid are separated by crystallisation.

Use of a compound as defined in any one of claims 1 to 4 for the manufacture of a medicament for the treatment of a condition where a 5-HT 1 -like agonist is indicated.

11. Use of a compound as defined in any one of claims 1 to 4 for the manufacture 20 of a medicament for the treatment of migraine. 4*

12. A method of treatment of a condition wherein a 5-HT 1 -like agonist is indicated, which comprises administering to a subject in need thereof an effective amount of an enantiomer of formula or a physiologically acceptable salt thereof, solvate or hydrate 25 thereof, as defined in any one of claims 1 to 4. 4

13. A method according to claim 12 wherein the condition is migraine.

14. A pharmaceutical composition comprising an enantiomer of formula or a .30 physiologically acceptable salt, solvate or hydrate thereof as defined in any of claims 1 to 4 P:\OPER\PDB\28517-97.137 17/5/99 and a physiologically acceptable carrier.

A compound according to claim 1 or a process according to claim substantially as hereinbefore described with reference to the Examples.

16. A use according to claim 10 or a method according to claim 12, or a composition according to claim 14 substantially as hereinbefore defined with reference to the Examples. DATED this 17th day of May 1999 SmithKline Beecham plc. By its Patent Attorneys DAVIES COLLISON CAVE oo *4 4* 4 4 o