title: Synthesis of thiophenecarboxamides, thieno[3,4-c]pyridin-4(5H)-ones and thieno[3,4-d]pyrimidin-4(3H)-ones and preliminary evaluation as inhibitors of poly(ADP-ribose)polymerase (PARP).
abstract: Inhibitors of poly(ADP-ribose)polymerase (PARP) inhibit repair of damaged DNA and thus potentiate radiotherapy and chemotherapy of cancer. Treatment of 3-cyanothiophene with potassium nitrate and concentrated sulphuric acid gave 5-nitrothiophene-3-carboxamide. 4-Nitrothiophene-2-carboxamide and 5-nitrothiophene-2-carboxamide were formed similarly from 2-cyanothiophene. Reduction with tin(II) chloride gave the corresponding aminothiophenecarboxamide salts which were isolated via their N-Cbz derivatives. Lithiation of 3,4-dibromothiophene at -116 degrees C and quenching with alkyl chloroformates gave 4-bromothiophene-3-carboxylates, which were hydrolysed to 4-bromothiophene-3-carboxylic acid. Hurtley reactions with the enolates of pentane-2,4-dione and of 1-phenylbutane-1,3-dione, followed by acyl cleavage, led to 4-(2-oxopropyl)thiophene-3-carboxylic acid and 4-phenacylthiophene-3-carboxylic acid, respectively. Condensation with ammonia in acetic acid gave 6-methyl- and 6-phenylthieno[3,4-c]pyridin-4-ones, which were selectively nitrated at the 1- and 7-positions or were dinitrated. Ethyl 4-acetamido- and 4-benzamido-thiophene-3-carboxylates were cyclised to 2-methyl- and 2-phenyl-thieno[3,4-d][1,3]oxazin-4-ones, respectively. Ring-opening with ammonia and recyclisation led to 2-substituted thieno[3,4-d]pyrimidin-4-ones. The aminothiophenecarboxamides are analogues of 3-aminobenzamide, a selective inhibitor of poly(ADP-ribose)polymerase (PARP); the thienopyridinones and the thienopyrimidinones are analogues of isoquinolin-1-ones and quinazolin-4-ones, respectively, which inhibit this enzyme. In preliminary assays, several thienopyridinones and thienopyrimidinones showed potent inhibitory activity against PARP.
authors.affiliation: Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, UK.
authors.forename: A E
authors.initials: AE
authors.lastname: Shinkwin
authors.forename: W J
authors.initials: WJ
authors.lastname: Whish
authors.forename: M D
authors.initials: MD
authors.lastname: Threadgill
mesh_terms: D000818:Animals; D002460:Cell Line; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008956:Models, Chemical; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011728:Pyridones / Q000138:chemical synthesis*; D011744:Pyrimidinones / Q000138:chemical synthesis*; D013876:Thiophenes / Q000138:chemical synthesis*
chemical_list: D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011728:Pyridones; D011744:Pyrimidinones; D013876:Thiophenes