Details for Patent: 7,692,006

Title:	Phthalazinone derivatives
Abstract:	4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one as crystalline Form A.
Inventor(s):	Menear; Keith Allan (Cambridge, GB), Ottridge; Anthony Peter (Cambridge, GB), Londesbrough; Derek John (Sunderland, GB), Hallett; Michael Raymond (Sunderland, GB), Mulholland; Keith Raymond (Macclesfield, GB), Pittam; John David (Macclesfield, GB), Laffan; David Dermot Patrick (Macclesfield, GB), Ashworth; Ian Woodward (Macclesfield, GB), Jones; Martin Francis (Macclesfield, GB), Cherryman; Janette Helen (Macclesfield, GB)
Assignee:	Kudos Pharmaceuticals Limited (London, GB)
Filing Date:	Oct 17, 2007
Application Number:	11/873,671
Claims:	1. A method of obtaining 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one (compound A) as crystalline Form A comprising the steps of: (i) crystallising 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one from a solvent; (ii) if the original solvent is not ethanol, treating the crystalline compound A with ethanol; (iii) treating the crystalline compound A containing trapped ethanol obtained from either step (i) or step (ii) with water to remove trapped ethanol; (iv) drying the resulting product. 2. A method of obtaining 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one (compound A) as crystalline Form A comprising the steps of: (i) crystallising 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one from a solvent; (ii) if the original solvent used in the synthesis of compound A in the crystalline form is not a mixture of water and a C.sub.1-2 alcohol, heating the compound with a mixture of water and a C.sub.1-2 alcohol; (iii) distilling the mixture from step (ii) at ambient pressure; and (iv) drying the resulting product from step (iii). 3. A method of obtaining 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one (compound A) as crystalline Form A comprising the steps of: (i) suspending compound A in a mixture of water and a C.sub.1-2 alcohol as the solvent; (ii) heating the suspension from step (i) to reflux; (iii) cooling the solution from step (ii) and seeding with compound A as Form A; (iv) drying the resulting product from step (iii). 4. A method of synthesising 4-[3-(4-cyclopropanecarbonyl-piperazine-1-carbonyl)-4-fluoro-benzyl]-2H-p- hthalazin-1-one from 4-[4-fluoro-3-(piperazine-1-carbonyl)-benzyl]-2H-phthalazin-1-One comprising the step of: (i) adding a pre-mixed solution of triethylamine and cyclopropane carbonyl chloride, in an organic solvent, to 4-[4-fluoro-3-(piperazine-1-carbonyl)-benzyl]-2H-phthalazin-1-one in the same organic solvent with the temperature of the solution being controlled to be below 2000. 5. A method synthesising 2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-benzoic acid, comprising the step of: (i) synthesising diethyl (3-oxo-1,3-dihydro-2-benzofuran-1-yl)phosphonate from 2-carboxybenzaldehyde by reaction with the sodium salt of diethyl phosphite, followed by reaction with methanesulphonic acid; (ii) synthesising 2-fluoro-5-[(E/Z)-(3-oxo-2-benzofuran-1(3H)-ylidene)methyl]benzonitrile from diethyl (3-oxo-1,3-dihydro-2-benzofuran-1-yl)phosphonate, by reaction with triethylamine in 2-methyltetrahydrofuran. 6. The method of claim 5, further comprising the step of: (i) synthesising 2-fluoro-5-[(4-oxo-3,4-dihydrophthalazin-1-yl)methyl]benzonitrile (ED): ##STR00014## from compound E: ##STR00015## by reaction with hydrazine hydrate; and (ii) synthesising compound D: ##STR00016## from compound ED by reaction with sodium hydroxide. 7. 2-Fluoro-5-[(4-oxo-3,4-dihydrophthalazin-1-yl)methyl]benzonitrile (ED): ##STR00017##