WO1995026729A1

WO1995026729A1 - New prostaglandin derivatives for the treatment of glaucoma or ocular hypertension

Info

Publication number: WO1995026729A1
Application number: PCT/SE1995/000347
Authority: WO
Inventors: Johan Stjernschantz; Bahram Resul
Original assignee: Pharmacia Ab
Priority date: 1994-03-31
Filing date: 1995-03-31
Publication date: 1995-10-12
Also published as: SE9401087D0; AU2155995A

Abstract

Therapeutically active and physiologically acceptable 11-deoxy or 15-deoxy prostaglandin F2α derivatives containing a ring substituted omega chain and their use for the preparation of compositions for the treatment of glaucoma or ocular hypertension.

Description

New Prostaglandin Derivatives for the Treatment of

Glaucoma or Ocular Hypertension.

The present invention is related to new derivatives of prostaglandin F_2α in which part of the omega chain has been substituted with a ring structure and one or more of the hydroxy groups on carbon atoms 11 or 15 has been removed, as well as their use for treatment of glaucoma or ocular

hypertension. The invention also relates to ophthalmic

compositions containing an active amount of said prostaglandin derivatives and to the manufacture thereof.

Glaucoma is an eye disorder characterized by increased intraocular pressure, excavation of the optic nerve head, and gradual loss of the visual field. An abnormally high

intraocular pressure is commonly known to be detrimental to the eye, and there are clear indications that in glaucoma the intraocular pressure is the most important factor causing degenerative changes in the retina and the optic nerve head. The exact pathophysiological mechanism of open angle glaucoma is, however, still unknown. Unless untreated, glaucoma may lead to blindness, the course of the disease typically being slow with progressive loss of vision.

The intraocular pressure (IOP) can be defined according to the formula:

IOP = Pe + (Ft - Fu) × R (1) where Pe is the episcleral venous pressure, Ft the total formation of aqueous humour and Fu the part of the aqueous humor which exits the eye through the uveoscleral outflow pathway and R is the resistance in the trabecular outflow pathway. The aqueous humour in the anterior and posterior chambers of the eye is formed in the ciliary processes behind the iris. It then flows through the pupil into the anterior chamber and normally exits the eye through the trabecular meshwork and Schlemm's canal into the episcleral veins outside the eye globe. However, part of the aqueous humour may leave the eye through the uveoscleral outflow route (Bill 1975).

IOP in humans is normally in the range of 12-22 mmHg. At higher values, e.g. above 22 mmHg, there is an increased risk that the eye may be affected. In one particular form of

glaucoma, low tension glaucoma, damage may occur at pressure levels that are within the normal physiological range. The opposite situation is also known, i.e. some individuals may exhibit an abnormally high intraocular pressure without any manifest defects in the visual fields or the optic nerve head. Such conditions are usually referred to as ocular hypertension.

Glaucoma treatment can be given by means of drugs, laser or surgery. In drug treatment the purpose is to lower either the formation of aqueous humour (Ft) or the resistance (R) which according to formula (1) above will result in reduced intraocular pressure; alternatively to increase the outflow of aqueous humour through the uveoscleral route which according to the same formula also reduces the intraocular pressure.

Prostaglandins, and in this group especially PGF_2α and its derivatives like esters and various analogues, reduce

intraocular pressure mainly by increasing uveoscleral outflow of aqueous humour (Crawford et al (1987), Nilsson et al (1989), Stjernschantz and Resul (1992), Toris et al (1993)). The use of prostaglandins and their derivatives is described in several patents and patent applications, for instance in US 4599353 (Bito), US 4952581, WO89/03384 (Resul and Stjernschantz), EP 170258 (Cooper), EP 253094 (Goh), EP 308135 (Ueno) and EP

471856 (Kishi et al)

With respect to the practical usefulness of many of the prostaglandins and their derivatives as suitable drugs for treatment of glaucoma or ocular hypertension, a limiting factor is their property of causing superficial irritation and

vasodilation in the conjunctiva. However, it was found by the present inventors that these side-effects effectively could be eliminated, while the IOP lowering effect was maintained, by introducing a ring structure in the omega chain, preferably a phenyl group on carbon 17. This concept is the subject of the above-mentioned patent application WO89/03384. Recently 15-deoxyprostaglandin derivatives were described as IOP depressants in a patent application by Kishi et al (see EP 471856). Even if it is claimed that these analogs exert less side effects in the eye it must be pointed out that they exhibit much less biologic activity in general compared to the naturally occurring prostaglandins, making them less

interesting as drug candidates for ophthalmic use.

We have now surprisingly found that 15-deoxy derivatives of PGF_2α, in spite of the low activity indicated in prior art literature, exert sufficient biologic activity to be used as therapeutic agents in the treatment of increased intraocular pressure if these analogues are substituted with a ring

structure on the omega chain. The considerably increased activity obtained by the introduction of a ring structure on the omega chain was not expected since the major effect of such a substitution according to prior art was to eliminate

undesirable side effects.

Naturally occurring PGF_2α has the general structure:

where the upper side chain is called the alpha chain and the lower side chain is called the omega chain. The position of certain carbon atoms in the structure, starting from the hydroxyl group in the alpha chain, is indicated.

Prostaglandin derivatives according to the present

invention are derivatives with the general structure:

wherein R₁ is OOH, the active acid form, or an amide group or an ester moiety comprising an alkyl group, preferably with 1-10 carbon atoms, especially 1-6 carbon atoms, for instance methyl, ethyl, propyl, isopropyl, butyl, isobutyl, neopentyl or benzyl groups. R₂ is hydrogen or a small alkyl group,

especially methyl, methylene or ethyl. Moreover, the

cyclopentane ring might contain more than one substituent R2.

D is a carbon chain with 3-12, preferably 3-8, and

especially 3-5, atoms in the chain. The chain D contains a double bond, for instance between carbons 13-14 , or 14-15, or 15-16 or 16-17. The double bond may also be located further to the end of the omega chain in cases of extended chains. The double bond between carbon 13 and 14, corresponding to the naturally occurring PGF_2α represents the presently preferred embodiment. The carbon chain is optionally interrupted by preferably not more than one atom selected from the group comprising nitrogen, sulphur or oxygen. The chain may also be substituted by one or more "inert" groups, for instance lower alkyl groups, especially with 1-3 carbon atoms.

D may also contain a hydroxy group on carbon 15 in cases when the substituent on carbon 11 is not a hydroxy group.

R3 is a ring structure selected from the group comprising (i) aromatic rings, such as a phenyl group which is

unsubstituted or substituted with one or more substituents selected from C1-C5 alkyl groups, C1-C4 alkoxy groups,

trifluoromethyl groups, C1-C3 aliphatic acylamino groups, nitro groups, halogen atoms, and a phenyl group; or

(ii) heteroaromatic rings, such as thiazol, imidazole,

pyrrolidine, thiophene and oxazole, which is unsubstituted or substituted with one or more substituents selected from C1-C5 alkyl groups, C1-C4 alkoxy groups, trifluoromethyl groups, C1-C3 aliphatic acylamino groups, nitro groups, halogen atoms, and a phenyl group; or

(iii) cycloalkane or cycloalkene rings with 3-7 carbon atoms in the ring, optionally substituted with lower alkyl groups with 1-5 carbon atoms.

R₄ is OH, provided that carbon atom 15 is not substitued with OH, or a lower alkyl group. It is further within the scope of the invention to employ prostaglandin derivatives analogous to the formula given above but in which minor modifications have been introduced by

"inert" substituents, for instance in such positions that the specificity for the prostaglandin receptor is not appreciably affected. Examples of such modifications include derivatives with cis and trans configuration of the double bond between carbons 5 and 6 as well as other locations of the double bond on the alpha chain and various substituents on the alpha chain.

The invention thus relates to certain deoxy derivatives of PGF2α in which not more than one of carbon atoms 11 and 15 may contain a hydroxy group, and in which the omega chain is substituted to contain a ring structure as well as the use of such derivatives for treatment of glaucoma or ocular

hypertension. The method for treatment comprises contacting an effective intraocular pressure reducing amount of a

composition, comprising a deoxy derivative, as defined above, and an ophthalmologically acceptable carrier, with the eye in order to reduce the eye pressure and to maintain said pressure at a reduced level. This therapy is applicable both to humans and animals. The composition contains about 0.1-100 μg,

especially 1-30 μg, per application of the active substance. The composition is applied topically on the eye 1-3 times daily. The effective amount comprises a dose of about

0.1-100 μg in about 10-50 μl.

Preparation of the composition is carried out by mixing the prostaglandin derivative with an ophthalmologically

compatible carrier. Such carrier compounds are known per se and there are a number of systems based on physiologic saline, oil solutions or ointments suggested in the literature for

application of medicaments to the eye. The carrier or vehicle may furthermore contain ophthalmologically compatible

preservatives such as e.g. benzalkonium chloride, surfactants, such as polysorbate 80, liposomes or polymers, for example methyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone and hyaluronic acid. The latter substances may be used for

increasing the viscosity of the solution. Furthermore it is also possible to use soluble or insoluble drug inserts, for instance gels or gel type matrices, in order to obtain a slow-release system.

The invention is further described in a series of

experiments concerning synthesis as well as use of compounds according to the invention.

Example 1. Synthesis of 11-deoxy-17-phenyl-18,19,20- trinor-PGF_2α isopropyl ester 10 (Scheme 1)

1.1. Synthesis of (1S,5R,6R,7R)-6-t-butyldimethylsilyloxymethyl-7-hydroxy-2-oxabicyclo [3,3,0] octane-3-one 2

Imidazol (15.7g, 0.232moL) was added to a stirred solution of the lactone 1 (20g, 0.116 moL) in DMF (60mL) at room

temperature. The mixture was allowed to cool to 0°C when t-butyldimethylsilyl chloride (17.6g, 0.116 moL) was added and the mixture was stirred for 4-5 h (TLC monitoring). The

reaction mixture was quenched with addition of methanol (40 mL). The mixture was warmed to room temperature followed by addition of water (50 mL) and extracted with ethyl acetate (2×60mL), dried with sodium sulfate, filtered, the solvent was removed in vacuo. The residue was chromatographed on silica gel using ethyl acetate as eluent to give a white crystalline product m.p. = 60.5-62 yield 87%.Rf=0.16 (hexane:ethylacetate 2:1).

1.2. (1S,5R,6R,7R)-6-t-butyldimethylsilyloxymethyl-7-(4-tolylsulfonyloxy)-2-oxabicyclo [3,3,0] octane-3-one 3

Pyridine (50 mL) was added to a cooled 0ºC solution of the lactone 2 (20g, 0,08 moL) in dichloromethane (170 mL). 4-tolylsulfonylchloride ( 60g, 0.32 mol) was added in small portions over 20 min. with stirring. The resulting mixture was stirred at -5°C to 0°C for 20 min. and then at room temperature for 3h (TLC monitoring). The reaction mixture was diluted with ice-water (50mL), extracted twice with dichloromethane

(2×120mL). The organic layer was washed with 5% citric acid (2×130mL), dried with sodium sulfate, evaporated to give a crystalline product yield 90%, Rf 2.5 (hexane:ethylacetate 2:1).

1.3. Synthesis of (1S, 5R,6R)-6-t-butyldimethylsiloloxymethylene-2-oxabicyclo-[3,3,0]-6-octene-3-one 4

To a solution of the tosylate 3 (25g, 0.06 moL) in THF (130 mL) was added droppwise a solution of tetrabutylammonium fluoride (28.4g, 0.09moL) in THF (80 mL) with stirring at room temperature. The mixture was stirred overnight (TLC

monitoring). Then water (120 mL) was added and to this mixture ethyl acetate (200ml) was added. The organic layer was washed with sodium hydrogenecarbonate (2×80mL). The solvent was removed invacuo, chromatographed on silicagel (ethyl acetate) to give the desired product, the unsaturated lactone 4. as oil yield 5.5g 60%. ¹H NMR (CDCl3) d 2.4(dd, 1H), 2.85 (m, 2H), 3.0(m, 1H), 3.6 (m, 1H), 3.7 (m, 1H), 5.6 (dt, 1H), 6.0 (m, 1H).

1.4. Synthesis of (1S,5R,6S)-6-hydroxymethyl-2-oxabicyclo- [3,3,0]-octane-3-one 5

To a suspention of 10% Pd/C (0.3g)in ethanol (15 mL) was added a solution of lactoe 4.. (5g, 0.032 mol). The solution was stirred under hydrogene atmosphere for four h (TLC monitoring). The catalyst was removed by filtration through celite pad, washed with ethanol (20 mL), the solvent was removed in vacuo. The resulting oil was dissolved in ethyl acetate (80 mL) and washed with water (50 mL), brine (30 mL), the organic phase was dried with sodium sulfate. The solvent was removed in vacuo to give 5 as a colourless oil, yield 4.4g 91% ¹H NMR (CDC13) d 1.5

(m, 1H), 2.0 (m, 4H), 2.45 (d, 1H), 2.65 (m, 1H), 2.85 (m, 1H),

3.6 (dq, 2H), 3.7 (m, 1H), 5.0 (m, 1H).

1.5. Synthesis of (1S,5R,6R)-6-(3-oxo-5-phenyl-1E-pentenyl)-2-oxabicyclo(3,3,0)-octane-3-one 6 To a solution of the alcohol 5 (4 g, 0.026 mol) in DME (40 mL), cooled to 18° C, was added dicyclohexylcarbodiimide (DCC)

(16g, 0.078 mol), dimethylsulfoxide (11.5 mL, 0.1625 moL) and phosphoric acid (1.02g, , 0.01mol). The temperature of the reaction mixture was kept below 25° C for 30 min. The reaction mixture was stirred at room temperature for additional 2 hours

(TLC monitoring), the precipitate was removed by filtration and washed with ether (2×50 mL). The combind organic layer was washed with water (50 mL) and brine (2×50mL), the aqueous solution was extracted with ether (100 mL), the organic layers were collected and dried with sodium sulfate, filtered, and used directly for the Wadswarth Emmon reaction.

To a suspension of 2-oxo-4-phenylbutyltriphenylphosphine

(28.5g, 0.07mol), in DME (100 mL) was added dropwise to the above solution of aldehyde at a rate that the temperature of the reaction not exceed 25 ºC. After 5 hours (TLC monitoring) the reaction mixture was quenched with AcOH, the precipitate was removed by filtration, the solvent was removed and to the residue was added EtOAc (200mL). The solution was washed with water (50 mL) and brine (50 mL). The organic layer was dried over anhydrous sodium sulfate. The solvent was removed in vacuo, the oil was chromatographed on silica gel (EtOAc), Rf 0.66 (EtOAc) yield 3.4g, 46%

1H NMR (CDCl3) d 2.0 (m, 2H), 2.2 (m, 1H), 2.35 (d, 1H), 2.45 (m, 1H), 2.55 (m, 1H), 2.85 (m, 2H), 2.95 (m, 2H), 5.0 (m, 1H), 6.1 (d, 1H), 6.65 (q, 1H), 7.2 (m, 3H), 7.3 (m, 2H).

1.6. (1S,5R,6R)-6-(3-hydroxy-5-phenyl-1E-pentenyl)-2-oxabicyclo(3,3,0)-octane-3-one 7

To a solution of the lactone 6 (3.3g, 0.012moL) in

methanol :dichloromethane 1:1 (50mL) at -78°C is added sodium borohydride (0.35g, 0.009mol) in small portion, after 40 min (TLC monitoring) the reaction mixture is quenched with 1N HCl (5 mL) and extracted with ethyl acetate (2×10mL), dried over sodium sulfate, concentrated in vacuo afforded the

corresponding epimeric mixture of alcohols and chromatographed on silica gel (toluene: ethyl acetate 1.2) to give a white crystslline product yield 1.3g 38%, Rf=0.27 (diethyl ether)

1.7. (1S,5R,6R)-6-(3-hydroxy-5-phenyl-1E-pentenyl)-2-oxabicyclo(3,3,0)-octane-3-ol 8

A solution of diisobutylaluminium hydride (DIBAL) (1.26 g, 0.0088mol) ) in dry THF (15 mL) was added dropwise to a stirred solution of the lactone 1 (1.25g, 0.0044mmol) in dry THF (20mL) at -72/-80º C. After 1 h. (TLC monitoring), the reaction mixture was quenched with methanol (10 mL) and was warmed to room temperature followed by addition of water (30mL),

extracted with EtOAc (2×60mL). The organic phase was dried with sodium sulfate, filtered, and triethylamine (0.1mL) was added to stabilise the triol. The solvent was removed in vacuo, the residue was chromatographed on silica gel using EtOAc as eluent, to give a colourless oil product , yield 0.93g, (73%). mp 102-104°, R_f = 0.31 (AcEOt:acetone 1:1), [a]²⁰ _D =-22.08° (c = 0.18,

¹H NMR (CDCl3) d 2.1 (m, 3H), 2.3 (m, 1H), 2.55 (m, 1H), 2.7 (m, 3H), 4.1(m, 2H), 4.7 (dm, 1H), 5.5 (m, 4H), 7.2 (m, 3H), 7.3 (m, 2H).

1.8. 11-deoxy-17-phenyl-18,19,20-trinor-PGF_2α. 9

Sodium methylsulfinylmethide (2.13g, 0.021mol) freshly prepared from sodium hydride and DMSO was added dropwise to a stirred suspension of 4-carboxybutyl triphenyl phosphonium bromide (4.8 g, 0.011 mol) in DMSO (20 mL) under nitrogen. To the resultant red orange solution of ylide at room temperature was added the lactol 8 ( 0.9 g, 0.00313 mol) in DMSO (5 mL), and the mixture was stirred for 3-4 h. (TLC monitoring). The reaction mixture was diluted with water (20 mL) and washed with ether (4×40 mL). The water layer was acidified with 5% citric acid to pH=4 and extracted with EtOAc (2×40 mL). The organic phase was washed with brine (30 mL), dried on sodium sulfate, and filtered. The solvent was removed in vacuo, and the slurry 9 was used directly without isolation for the next step. 1.9. 11-deoxy-17-phenyl-18, 19, 20-trinor-PGF2α isopropyl ester. 10

DBU (1.03 g, 0.0067 mol) was added dropwise to a stirred solution of the crude product 9. (0.9 g, 0.00313 mol) in acetone (15 mL) at 0° C. The mixture was allowed to warm to room temperature. When isopropyl iodide (1.02 g, 0.006 mol) was added dropwise. After 8 h (TLC monitoring). The mixture was diluted with EtOAc (80 mL), washed with brine (30 mL), citric acid 3% (2x25 mL) and sodium hydrogen carbonate 5% (2×25 mL) and dried over anhydrous sodium sulfate. The solvent was removed in vacuo and the residue was chromatographed on silica gel using a gradient elution with dichloromethane, dichloromethane :

ethanol 10:0.5 and ethyl acetate successively. This afforded a colourless oil, yield 0.36g (36%). Rf =0.0.27 (EtOAc :hexane 1:1) ¹H NMR (CDCI₃) d 1.2 (d, 6H), 1.42 (m, 2H), 1.65 (m, 6H), 1.8-2.2 (m, 5H), 2.35 (t, 2H), 2.40 (d, 1H), 2.65-2.70 (m, 2H), , 4.1 (m, 1H), 4.25 (m, 1H) , 5.0 (sept. 1H), 5.35 (m, 2H), 5.55 (m, 2H), 7.19-7.27 (dm, Ar); ¹³C NMR (CDCI₃) d 173.37 (C=0), 141.96, 135.48, 133.07 129.53(C5), 129.43(C6), 129.43, 128.43, 128.37, 125.8, 73.74 (C9), 72.21(C15), 67.60, 51.84, 45.51, 38.93, 34.07, 33.54,31.88, 30.03, 26.63, 24.99, 21.85 EXAMPLE 2. SYNTHESIS OF 11-DEOXY-11-METHYL-17-PHEΝYL-18,19,20-TRINOR-PGF_2α ISOPROPYL ESTER 18. (SCHEME 2)

2.1. (1S,5R,6R,7R)-6-(3S-(2-tetrahydropyranyloxy)-5-phenyl-1-pentenyl)-7R-(2-tetrahydropyranyloxy)-2-oxabicyclo- (3.3.0)-octane-3-ol. 12

A solution of diisobutylaluminium hydride (DIBAL) (8g, 0.046 mol) in dry THF (40 mL) was added dropwise to a stirred solution of the lactone 11 (11g, 0.023mol) in dry THF (20mL) at -72/-80° C. After 1 h. (TLC monitoring), the reaction mixture was quenched with methanol (20 mL) and was warmed to room temperature followed by addition of water (30mL), extracted with EtOAc (2×60mL). The organic phase dried with sodium sulfate, filtered, and triethylamine (0.1mL) was added to stabilise the triol. The solvent was removed in vacuo, the residue was chromatographed on silica gel using EtOAc as eluent, afford the corresponding lactol 12 as a colourless oil product , yield 7.6g, (76%). mp 102-104°, R_f = 0.20

(AcEOt:hexane 1:1), ¹H NMR (CDCl3) d 1.55 (m, 5H), 1.7-1.8(m, 2H), 1.9-2.1 (m, 2H), 2.3-2.5 (m, 2H), 2.6-2.7 (m, 1H), 3.5 (m, 1H), 3.9 (m, 1H), 4.1(m, 1H), 4.7 (m, 2H), 5.3-5.7 (m, 4H), 7.2 (m, 3H), 7.3 (m, 2H).

2.2. 11,15-bistetrahydropyranyloxy-17-phenyl-18,19,20-trinor PGF_2α isopropyl ester 14.

Sodium methylsulfinylmethide ( 4.84g, 0.048mol) freshly prepared from sodium hydride and DMSO (20mL) was added dropwise to a stirred suspension of 4-carboxybutyl triphenyl

phosphonium bromide (13.9g, 0.032 mol) in DMSO (20 mL) under nitrogen. To the resultant red orange solution of ylide at room temperature was added the lactol 12 ( 7.5g, 0.016 mol) in DMSO (10 mL), and the mixture was stirred for 3-4 h. (TLC monitoring). The reaction mixture was diluted with water (20 mL) and washed with ether (4×40 mL). The water layer was acidified with 5% citric acid to pH 4 and extracted with EtOAc (2×80 mL). The organic phase was washed with brine (50mL), dried on sodium sulfate, and filtered. The solvent was removed in vacuo, and the slurry 13 was used directly without isolation for the next step (esterification).

To the stirred solution of the crude product 13 (8.3.

0.015 mol) in acetone (30mL) DBU (4.8g, 0.013 mol) was added dropwise at 0° C.

The mixture was allowed to warm to room temperature. When isopropyl iodide (6.88g, 0.04mol) was added dropwise. After 4 h (TLC monitoring). The mixture was diluted with EtOAc (100mL), washed with brine (40 mL), citric acid 3% (2×40 mL) and sodium hydrogen carbonate 5% (2×40 mL) and dried over anhydrous sodium sulfate. The solvent was removed in vacuo and the residue was chromatographed on silica gel using ethyl acetate as eluent, afforded the corresponding ester 14 as an oil, Rf=0.29

(hexane: EtOAc 3:2), Yield 4.4g (49%) 2.3. 11,15-bistetrahydropyranyloxy-17-phenyl-18,19,20-trinor P6E2 isopropyl ester 15

To a stirred solution of 14 (4.2g, 0.007 mol) in acetone (20 ml) was added pyridinium chlorochromate (1.7g, 0.0078 mol) in small portions, with stirring at room temperature for 3hr. (TLC monitoring). The reaction mixture was diluted with ether (100 mL), the precipitate was removed by filtration, being rinsed well with ether (50 mL). The solvent was removed in vacuo, the residue was dssolved in ether (150 mL), washed with saturated sodium hydrogencarbonate (3×50 mL), and brine (50 mL), dried (MgSO4), concentrated to give a light yellow

oil. This oil was chromatographed on silicagel (ether) to give the desired product 15, Rf= 0.38 (hexane:EtOAc 3:2), Yield 3.4g (82%).

2.4. 17-phenyl-18,19,20-trinor PGA2 isopropyl ester 16

To a stirred solution of 15 (3.0g, 0.0017) in THF (60 mL) was added HCl 2M (2mL). The solution was stirred at room temperature for 8hr. (TLC monitoring), poured in to water (20 ml), extracted with ether (4x40mL), washed with brine, dried (MgSO4), and evaporated to give a yellow oil, which was

chromatographed on silica gel (hexane:EtOAc 2:1), yield 0.24g, (45%) , ¹H NMR (CDCI₃) d 1.25 (d, 6H), 1.7 (m, 3H), 1.9 (m, 3H), 2.0-2.2 (m, 4H), 2.3 (t, 3H), 2.5 (m, 1H), 2.7 (m, 2H), 3.25 (m, 1H), 4.15 (m, 1H), 5.0 (sept, 1H), 5.3-5.5 (dm, 2H), 5.6 (m, 2H), 6,2 (d, 1H), 7.2 (m, 3H), 7.3 (m, 2H), 7.5 (m, 1H).

2.5. 11-deoxy-11-methyl-17-phenyl-18,19,20-trinor PGE2 isopropyl ester 17

To a cold solution of MeLi -78 ºC (0.07g, 3mmol) in ether (30 mL) under argon atmosphere was added CuI (0.323g, 1.7mmol) under stirring. After 1hr at -78 ºC, a solution of PGA ester 16 (0.22g, 0.54 mmol) in dry ether was added over a period of 5 min. After stirring for 20 min. ( TLC monitoring) at this temperature, the mixture was quenched with saturated aquious solution (10 mL) under vigorous shaking. The organic layer was separated and the aquious layer was extracted with ether (50 mL). The ether layer was dried (MgSO4), evaporated and

chromatographed on silica gel (benzene: EtOAc 3:1), to give the desired product 12 Rf = 0.39 (benzene: EtOAc 3:1). yield 0.20g (90%). ¹H NMR (CDCI3) d1.1 (d, 3H), 1.25 (d, 6H), 1.6 (m, 3H), 1.9 (m, 3H), 2.0-2.1 (m, 4H), 2.25 (t, 3H), 2.35 (m, 1H), 2.55 (dd, 1H), 2.7 (m, 2H), 4.15 (m, 1H), 5.0 (sept, 1H), 5.3-5.45 (dm, 2H), 5.5-5.7 (m, 2H), 7.2 (m, 3H), 7.3 (m, 2H).

2.6. 11-deoxy-11-methyl-17-phenyl-18,19,20-trinor PGF_2α isopropyl ester 18

To a stirred solution of lithium tri-sec-butvlborohydride (Lithium Selectride) (0.097g , 0.51 mmol) in THF (30 mL) at -95° C under nitrogen was added dropwise a solution of PGE2 17 (0.2g, 0.47mmol) in THF (10 mL) cooled to -75/-78° C. The reaction mixture was stirred for 1 h. (TLC monitoring), then quenched with saturated ammonium chloride. The temperature was raised to ±0° C, water (20 mL) was added, and the mixture was diluted with EtOAc (30 mL). The organic layer was separated and washed with brine, dried on anhydrous sodium sulfate,

concentrated in vacuo and chromatographed on silica gel using EtOAc as eluent , furnishing 18 as a colorless oil yield 0.18 g (91%); Rf = 0.37 (silica gel, hexane:EtOAc 3:2); ¹Η NMR (CDCl₃) d 0.95 (d, 3H), 1.25 (d, 6H), 1.6 (m, 5H), 1.9 (m, 4H), 2.1 (m, 4H), 2.25 (m, 3H), 2.7 (m, 2H), 4.15 (m, 1H), 4.25 (m, 1H), 5.0 (sept, 1H), 5.4 (dm, 3H), 5.6 (dd, 1H), , 7.2 (m, 3H), 7.3 (m, 2H).¹³C NMR (CDCl3) d 173.33 (C=O), 142, 134.7, 133.99, 129.58, 129.44, 128.32, 125.8, 72.9 , 72.04, 67.60, 54.2,51.26, 42.6, 39.0, 34.04,31.91, 26.63,25.2, 24.87, 21.85.19.62. EXAMPLE 3. SYNTHESIS OF 1-ISOPROPYL-17-PHENYL-18,19,20-TRINOR-9,11-D1HYDROXY-5,14-PROSTADIENOATE (5Z, 14E, 9S, 11R) AND (5Z,14Z,9S,11R) 27, 28 (SCHEME 3) 3.1. (1S, 5R, 6R, 7R)-6-(2-methoxy-1-ethenyl)-7-(4-phenyl benzoyloxy)-2-oxabicyclo-(3,3,0)-octane-3-one. 21

To a solution of the alcohol 19 (6.07g, 0.017 mol) in DME (100 mL), cooled to 18° C, was added dicyclohexylcarbodiimide (DCC) (10.66g, 0.0517 mol), and phosphoric acid (0.5 mL, 0.0086 mol). The temperature of the reaction mixture was kept below 25° C for 30.min. The reaction mixture was stirred at room temperature for additional 2 hours (TLC monitoring), the precipitate was removed by filtration and washed with ether (2×50 mL). The combind organic layer was washed with water (50 mL) and brine (2×50mL), the aqueous solution was extracted with ether (100 mL), the organic layers were collected and dried with sodium sulfate, filtered to give the crude aldehyde 20.

To a stirred suspension of methoxymethyl triphenyl

phosphonium chloride (11.9 g, 0.035 mol) in THF (20 mL) under nitrogen at 0-5° C was added potassium t butoxide (3.9g, 0.035 mol), and the mixture stirred for 30 min. at room temperature. To the resultant red orange solution of ylide at -15/-10º C was added the crude aldehyde 20 (6.07g, 0.0173mol) in THF (6 mL), and the mixture was stirred for 3-4 h. (TLC monitoring). The reaction mixture was diluted with water (15 mL) and extracted with ether (2×30 mL). The organic layer was washed with 5% citric acid (20mL) and with brine (30 mL), dried on sodium sulfate, and filtered. The solvent was removed in vacuo, the residue was chromatographed on silica gel (EtOAc:hexane 4:1) to give 21 as a colourless oil yield 3g (46%), Rf=0.63

(EtOAc:CH2Cl2 1:1)

¹H NMR (CDCI3) δ 2.45-2.85 (mm, 2H), 3.45 (d, 3H), 4.6 (m, 1H), 5.05-5.2 (m, 2H), 5.85(dd, 1H), 6.4(dd, 1H), 7.4-7.65(dm, 7H), 8.05(dd,2H). 3.2. (1S, 5R, 6R, 7R)-6-acetyl-7-(4-phenyl benzoyloxy)-2-oxabicyclo-(3.3.0)-octane-3-one. 22

To a stirred solution 21 (3.0g, 0.008mol) in THF :H₂O 2:l(10mL) was added 4-toluenesulfonic acid monohydrate (0.152g, 0.0008 mol). The resulting solutin was wormed to 90-100 °C for 2hr (tLC monitoring). Ether (100mL) was added, and the solution was washed with water (20 mL) and brine (20 mL), the organic layer was dried with sodium sulfate. The solvent was removed in vacuo, the residue was used directly wthout isolation for the next step. Rf 0.39 (EtOAc:CH2Cl2 1:1). 3.3. (1S, 5R, 6R, 7R)-6-(5-phenyl-2E,Z-pentenyl)-7-(4-phenyl benzoyloxy)-2-oxabicyclo-(3.3.0)-octane-3-one. 23

To a stirred suspension of 3 -phenylpropyl

triphenylphosphonium bromide (6.13g, 0.0133mol) in THF (20 mL) under nitrogen at 0-5° C was added potassium t butoxide (1.49 g, 0.013 mol), and the mixture stirred for 30 min. at room temperature. To the resultant red orange solution of ylide at -15/-10º C was added the aldehyde 22. (2.4 g, 0.0067 mol) in THF (5 mL), and the mixture was stirred for 3-4 h. (TLC

monitoring). The reaction mixture was diluted with ether (60 mL) and washed with saturated ammonium chloride (2×40 mL) and brine (30 mL), the organic layer was dried on sodium sulfate, and filtered. The solvent was removed in vacuo, and the slurry was chromatographed on silicagel (EtOAc:CH2Cl2) to give a colorless oil. which was then dissolved in benzene. Diphenyl sulfide (3.6g, 0.0192mol) was added, and irradiated with UV-365 nm under nitrogene atmosphere for 24hr. (HPLC monitoring), the mixture was diluted with ethyl acetate (80 mL), washed with water (50mL), 5% sodium hydrogencarbonate (40mL) and brine

(40mL). The organic layer was dried with sodium sulfate, and filtered. The solvent was removed in vacuo and the residue was chromatographed on silica gel (hexane:EtOAc 1.5:1). This afforded a white crystalline product 23 mp= 89-91 ºC Yield1.2g

( 39%) Rf = 0.27 (EtOAc). ¹H NMR (CDCI3) d 1.98 (m, 1H), 2.1- 2.2 (m, 2H), 2.3-2.5 (dm, 6H), 2.64-2.72(m, 2H), 2.76-2.84 (m, 1H), 5.0 (m, 1H), 5.2 (m, 1H), 5.4 (m, 1H), 5.9 (m, 1H), 7.16

(m, 3H), 7.24 (m, 2H), 7.38 (m, 3H), 7.58-7.68 (dm, 4H), 8.04

(m, 2H) .

3.4. (1S, 5R, 6R, 7R)-6-(5-phenyl-2EZ-pentenyl)-7-hydroxy-2-oxabicyclo-(3.3.0)-octane-3-one. 24

To a solution of the lactone 23 (0.95g, 0.002 mol) in methanol (10mL) was added potassium carbonate (0.17 g,

0.00122mol) and the mixture stirred at ambient temperature for 6 h. (TLC monitoring). The mixture was neutralised with IN C1 and extracted with EtOAc (2×20 mL). The organic phase was dried on anhydrous sodium sulfate and evaporated to dryness. The crude product was chromatographed (silica gel , EtOAc:hexane 2:1). The title compound 24 was obtained as a colourless oil, yield 0.53g (93%) R_f = 0.25 (EtOAc:hexane 2:1)

3.5. (1S,5R,6R,7R)-6-(5-phenyl-2EZ-pentenyl)-7-hydroxy-2-oxabicyclo-(3.3.0)-octane-3-ol. 25

A solution of diisobutylaluminium hydride (DIBAL) (0.66g, 0.0046mol) ) in dry THF (10 mL) was added dropwise to a stirred solution of the lactone 24(0.53g, 0.0019 mol) in dry THF (18mL) at -72/-80º C. After 1 h. (TLC monitoring), the reaction mixture was quenched with methanol (5 mL) and was warmed to room temperature followed by addition of ice-water (30 mL), 1M C1 (20 mL), extracted with EtOAc (2×40mL). The organic phase dried with sodium sulfate, filtered. The solvent was removed in vacuo, the residue was chromatographed on silica gel (ethyl acetate) furnishing 25 as a colorless oil R_f = 0.26 (EtOAc).

3.6. Isopropyl-9,11-dihydroxy╌17-phenyl-18,19,20-trinor prostadienoate (5Z, 14E, 9S, 11R) and (5Z, 14Z, 9S, 11R) 27 , 28.

To a stirred suspension of 4-carboxybutyl triphenyl phosphonium bromide (4.08g, 0.0092 mol) in THF (12 mL) under nitrogen at 0-5° C was added potassium t butoxide (2.06 g, 0.0184mol), and the mixture stirred for 40 min. at room temperature. To the resultant red orange solution of ylide at -20/-10° C was added the lactol 25 (0.53g, 0.0018 mol) in THF (5 mL), and the mixture was stirred for 5-6 h. (TLC monitoring). The reaction mixture was diluted with water (20 mL) and washed with ether (4×40 mL). The water layer was acidified with 5% citric acid to pH 4 and extracted with EtOAc (2×30 mL). The organic phase was washed with brine (30 mL), dried on sodium sulfate, and filtered. The solvent was removed in vacuo. To the stirred solution of the crude product 26 (0.68g, 0.0018 mol) in acetone (5mL) DBU (1.95 g, 0.013 mol) was added dropwise at 0° C. The mixture was allowed to warm to room temperature. When isopropyl iodide (1.9g, 0.011mol) was added dropwise. After 8 hr (TLC monitoring). The mixture was diluted with EtOAc (60 mL), washed with brine (30 mL), citric acid 3% (2×20 mL) and sodium hydrogen carbonate 5% (2×20 mL) and dried over anhydrous sodium sulfate. The solvent was removed in vacuo and the residue was chromatographed on silica gel using a gradient elution with dichloromethane : ethyl acetate 1:1 and ethyl acetate :

dichloromethane 2:1 successively. The 14E 27. and 14Z 28 were separated by column chromatography on silver nitrate

impregnated silica gel (ethyl acetate), to give the desired products as colourless oil, yield 27 (14E isomer) 0.08 g Rf = 0.28, 28 142 isomer 0.06g, Rf =0.20. (silicagel impregnated with silver nitrate, EtOAc).

27 1 4E ¹H NMR (CDCI₃) d 1.2 (d, 6H), 1.6-1.85 (m, 5H), 2.1- 2.3 (m, 4H), 2.32-2.4 (m, 6H), 2.68 (m, 2H), 3.9 (m, 1H), 4.16 (m, 1H). 5.0 (sept. 1H), 5.36 - 5.54 (m,4H db), 7.16-7.27 (dm, Ar); ¹³C NMR (CDCl3) d 173.28 (C=O), 141.87, 131.54, 129.54, 129.30, 128.71,128.44, 128.23, 125.72, 78.08 , 74.88, , 67.56,61.47, 52.68, 50.61, 42.22 , 36.31, 35.90, 34.26, 34.07, 29.69, 26.97, 26.67, 24.96, 21.86.

28 14Z ¹H NMR (CDCl₃) d 1.2 (d, 6H),1.7 (m, 3H), 1.82 (m, 2H), 2.14(m, 4H), 2.26-2.40 (m, 6H), 2.66 (m, 2H), 3.8 (m, 1H), 4.14 (m, 1H). 5.0 (sept. 1H), 5.36 - 5.54 (m,4H db), 7.16-7.27 (dm, Ar); ¹³C NMR (CDCI₃) d 173.29 (C=O), 141.87, 130.42,

129.64, 129.26, , 128.48, 128.27 128.16, 125.83, 78.37, 74.9, 67.56, 52.98, 50.91, 42.32 , 35.87, 34.09, 30.87, 29.39, 26.7, 24.96, 21.86.

Example 4. Synthesis of (5Z, 13E, 9S, 11R) -9, 11-dihydroxy-5,13-prostadienoic acid isopropyl ester (30), Scheme IV.

A solution of 29 (40 mg, 0.09 mmol) in 1 mL of 1,4-dioxane was added to a mixture of palladium acetate (1.2 mg, 5.4 mmol), triphenylphosphine (2.8 mg, 10.8 mmol), formic acid (4.2 mg, 0.09 mmol) and triethylamine (9.1 mg, 0.09 mmol) in 1 mL of dioxane. The reaction mixture was stirred at room temperature under nitrogen for 5 days and was diluted with ether. The ether solution was filtered through celite to remove palladium catalyst and was then concentrated

under reduced pressure. The resulting residue was

chromatographed on silica gel eluted with ethyl acetate:

hexane = 1:1 and followed with ether. Pure fractions were pooled and concentrated. Further purification by means of preparative HPLC (10 mL/min, ethanol/hexane = 2%) gives 13 mg (38%) of 30 as colorless oil.

¹NMR (CDCI₃): d 0.88 (t,J = 7 Hz, 3H), 1.22 (d,J = 6 Hz,

6H), 1.25-2.35 (m, 24H), 3.92 (m, 1H), 4.17 (m, 1H), 5.00

(sept,J = 6 Hz, 1H), 5.20-5.56 (m, 4H).

Example 5. Synthesis of (5Z, 13E, 9S, 11R)-9,11-dihydroxy-15-phenyl-5,13-prostadienoic acid isopropyl ester (32),

Scheme V.

A mixture of 31 (72 mg, 0.15 mmol),

bis (triphenylphosphino) palladium chloride [PdCl₂(PPh)₂] (2 mg, 3 mmol) formic acid (25 mg, 0.6 mmol) and

triethylamine (61 mg, 0.6 mmol) in 4 mL of 1,4-dioxane was stirred at 40 °C under nitrogen for 40 h. The reaction

mixture was diluted with ether, filtered (celite) and

concentrated. The residue was purified by fractional

chromatography on silica gel eluted with ethyl acetate: hexane = 1 : 1 followed by ether . The resulting fractions

were further purified by preparative HPLC (10 mL/min, 3% ethanol in hexane) to afford 10 mg (16%) of 32.

¹NMR (CDCI₃): d 1.22 (d,J = 6 HZ, 6H), 1.48-2.36 (m, 16H), 2.65 (t,J = 7 Hz, 3H), 3.95 (m, 1H), 4.25 (m, 1H), 5.25

(sept,J = 6 HZ, 1H), 5.26-5.61 (m, 4H), 7.15-7.32 (m, 5H).

Example 6. Studies on the biologic activity and adverse reactions of prostaglandin derivatives according to the

invention.

The experiments were carried out on cat eyes. The cat eye reacts with marked miosis (constriction of the pupil) to prostaglandins which stimulate FP receptors. The FP receptor is the receptor for PGF_2α, a naturally occurring prostaglandin

(Coleman, 1989). Our previous work shows that there is a good correlation between the miotic response (FP receptor

stimulation) in cats and the intraocular pressure reduction in primates and man (Stjernschantz and Resul, 1992). In the cat selective FP receptor agonists have little or no intraocular pressure reducing effect in contrast to primates and man

(Stjernschantz and Resul, 1992) . Furthermore the cat eye is a very good model for ocular irritation. Irritation was graded on a scale from 0 to 3 , 0 indicating complete absence of any signs of irritation and 3 maximal irritation as obvious from complete lid closure. The following compounds were tested on the cat eye: 1-isopropyl-17-phenyl-18,19,20-trinor-9,11-dihydroxy-5,14-prostadienoate (compounds 27 and 28 (cis- and trans isomers)), 11-deoxy-17-phenyl-18,19,20-trinor-PGF_2α-isopropyl ester

(compound 10), 11-deoxy-11-methyl-17-phenyl-18,19,20-trinor-PGF_2α-isopropyl ester (compound 18), 15-deoxy-17-phenyl- 18,19,20-trinor-PGF_2α-isopropylester (compound 32) and 15-deoxy-PGF_2α- isopropylester (compound 3ϋ.), a deoxy derivative of PGF_2α without ring substituted omega chain. The results of the tests are given in Table I and Table II. Table I. Maximum pupillary constrictive effect of deoxyprostaglandin F_2α analogs substituted with a ring structure in the omega chain

(compounds 28, 10,18 and 32) compared with a corresponding derivative without ring substitution (30).

Compound Dose Pupillary Stat.

No constrict. sign.

(μg) effect (mm) P-value

28 1 1.5±0.3 <0.05

28 10 2.5±0.5 <0.05

28 30 2.0±0.4 <0.01

10 1 3.7+0.8 <0.005

10 3 6.5±0.4 <0.001

10 10 7.3±0.5 <0.001

18 1 4.3±0.6 <0.001

18 3 7.3±0.4 <0.001

18 10 6.8±0.3 <0.001

32 3 1.3±0.5 <0.05

32 10 4.1±0.7 <0.005

30 10 0.5±0.6 >0.05

30 30 2.00±0.5 <0.01

Table II. Maximum ocular irritative effect of deoxy prostaglandin analogs substituted with a ring structure in the omega chain (Compounds 28 , 10, 18, 32) in comparision with a corresponding derivative without ring substitution (30).

Compound Dose Irritative Stat.

No effect sign.

(μg) (0-3) P-value

28 1 0.25±0.14 >0.05

28 10 0.50±0.20 >0.05

28 30 0.67±0.38 >0.05

10 1 0.75±0.25 <0.05

10 3 0.08±0.36 >0.05

10 30 0.25±0.17 >0.05

18 1 0.33±0.11 <0.05

18 3 0.25±0.11 >0.05

18 30 0.58±0.08 <0.001

32 3 0.25±0.11 >0.05

32 10 1.33±0.31 <0.01

30 10 0.25±0.11 >0.05

30 30 0.75±0.21 <0.02

As can be seen in Table I compounds 28, 10, 18 and 32 even at doses as low as 1-3 μg induced constriction of the cat iris. On the contrary compound 30. (without a ring ring structure in the omega chain) had very weak effect even at a dose of 10 μg. Thus, compounds 28, 10, 18 and 32 in spite of the fact that either the 15-hydroxy or 11-hydroxy group has been removed from the molecule still induce miosis in the cat. The compounds induced no or only slight irritative effect (Table II).

We have also tested the 14,15 cis and trans isomers 27 and 28 in an ordinary smooth muscle bath system measuring the tension of the iridial sphincter muscle isometriclly in vitro. It should be noted that the free acids and not esters of the compounds were used. In this system the EC-50 value of the trans isomer was 2×10^-7 M, whereas that of the cis isomer was

2×10-6 M, the trans isomer being approximately 10 times more potent than the cis isomer.

References

Crawford K and Kaufman PL (1987), Pilocarpine antagonizes

PGF_2alpha-induced ocular hypotension: Evidence for enhancement of uveoscleral outflow by PGF_2alpha, Arch. Ophthalmol 105:1112-1116.

Nilsson SFE, Samuelsson M, Bill A and Stjernschantz J (1989), Increased uveoscleral outflow as a possible mechanism of ocular hypotension caused by prostaglandin F_2alpha-1-isopropyl ester in the cynomolgus monkey, Exp Eye Res 48:707-716.

Stjernschantz J & Resul B (1992), Phenyl substitued

prostaglandin analogs for glaucoma treatment, Drugs of the Future 17(8):691-704.

Toris, Carol B, Camras Carl B and Yablonski Michael E (1993), Effects of PhXA41, A New Prostaglandin F_2α Analog, on Aqueous

Humor Dynamics in Human Eyes, Ophthalmology 100: 1297-1304.

Claims

Claims .

1. A composition for the treatment of glaucoma or ocular hypertension comprising a therapeutically active and

physiologically acceptable 11-deoxy or 15-deoxy prostaglandin F_2α derivative containing a ring substitued omega chain, wherein the ring is selected from the group comprising

(i) aromatic rings, such as a phenyl group which is

(ii) heteroaromatic rings, such as thiazol, imidazole,

pyrrolidine, thiophene and oxazole, which is unsubstituted or substituted with one or more substituents selected from C1-C5 alkyl groups, C1-C4 alkoxy groups, trifluoromethyl groups, C1- C3 aliphatic acylamino groups, nitro groups, halogen atoms, and a phenyl group; or

(iii) cycloalkane or cycloalkene rings with 3-7 carbon acorns in the ring, optionally substituted with lower alkyl groups with 1-5 carbon atoms,

in an ophthalmologically compatible carrier.

2. A composition according to claim 1, wherein the

prostaglandin derivative is a 15-deoxy prostaglandin

derivative.

3. A composition according to claim 1, wherein the

prostaglandin derivative is a 11-deoxy derivative.

4. A composition according to claims 2 or 3 wherein the derivative is a 17-phenyl-18,19,20-trinor derivative.

5. A composition according to any one of claims 1 to 4 wherein the prostaglandin derivative is the free acid, an amide or an ester, preferably an alkyl ester.

6. Method for treating glaucoma or ocular hypertension in a subject's eye which comprises contacting the surface of the eye with an effective intraocular pressure reducing amount of a therapeutically active and physiologically acceptable 11-deoxy or 15-deoxy prostaglandin F2α derivative containing a ring substituted omega chain, wherein the ring structure is selected from the group comprising

(i) aromatic rings, such as a phenyl group which is

(ii) heteroaromatic rings, such as thiazol, imidazole,

(iii) cycloalkane or cycloalkene rings with 3-7 carbon atoms in the ring, optionally substituted with lower alkyl groups with 1-5 carbon atoms..

7. Method according to claim 6 wherein the prostaglandin derivative contains a phenyl ring on carbon 17.

8. Use of a therapeutically active and physiologically acceptable 11-deoxy or 15-deoxy prostaglandin F_2α derivative containing a ring substitued omega chain wherein the ring structure is selected from the group comprising

(i) aromatic rings, such as a phenyl group which is

(ii) heteroaromatic rings, such as thiazol, imidazole,

(iii) cycloalkane or cycloalkene rings with 3-7 carbon atoms in the ring, optionally substituted with lower alkyl groups with 1-5 carbon atoms,

for the preparation of a composition for treatment of glaucoma or ocular hypertension.

9. Use according to claim 8 wherein the prostaglandin derivative is a 17-phenyl-18, 19, 20-trinor PGF_2α

10. 11-deoxy-11-methyl-17-18, 19, 20-trinor PGF_2α isopropyl ester

11. 1-isopropyl-17-phenyl-18,19,20-trinor-9,11-dihydroxy-5,14-prostadienoate

12. 11-deoxy-11-methyl-17-18,19,20-trinor PGF_2α isopropyl ester.

13. 11-deoxy-17-phenyl-18,19,20-trinor PGF_2α-isopropyl ester

14. 15-deoxy-17-phenyl-18,19,20-trinor-PGF_2α-isopropyl ester