Synthesis, Anticonvulsant Activity, and Structure−Activity Relationships of Sodium Channel Blocking 3-Aminopyrroles
摘要:
Starting from the corresponding acetophenone and glycine derivatives, a series of new 3-aminopyrroles was synthesized in few steps. Using this procedure with hydrazine and hydroxylamine instead of the glycinates provides access to S-aminopyrazoles and 5-amino-1,2-oxazoles. The various derivatives were tested for anticonvulsant activity in a variety of test models. Several compounds exhibit considerable activity with a remarkable lack of neurotoxicity. 4-(4-Bromophenyl)-3-morpholinopyrrole-2-carboxylic acid methyl ester, 3, proved to be the most active compound. It was protective in the maximal electroshock seizure (MES) test in rats with an oral ED50 of 2.5 mg/kg with no neurotoxicity noted at doses up to 500 mg/kg. Compound 3 blocks sodium channels in a frequency-dependent manner. The essential structural features which could be responsible for an interaction with an active site of the voltage-dependent sodium channel are established within a suggested pharmacophore model.
Mechanistic aspects of the synthesis of 3-aminopyrroles from substituted 2-methyl-1,2-thiazolium salts or 3-aminothioacrylamides
作者:Andreas Rolfs、Peter G. Jones、J�rgen Liebscher
DOI:10.1039/p19960002339
日期:——
The mechanism of the synthesis of 3-aminopyrroles 3 by ring transformation–desulfurisation of substituted 2-methyl-1,2-thiazolium salts 2 has been investigated. 3-Alkylideneaminothioacrylamides 4 and 2H-1,3-thiazines 5 could be synthesised by base treatment of 1,2-thiazolium bromides 2 and proved to be intermediates in the ring transformation–desulfurisation. Hitherto unknown bis(2-aminothiocarbonylvinyl)amines 6 are observed as by-products. When 3-phenacylaminothioacrylamide 1c is oxidised with hydrogen peroxide a novel pyrrole formation occurs to give 2-benzoylthiopyrrole 8a, where the sulfur atom is retained in the product. An erroneously reported 1,2-thiazolium-2-methanide 7 has been reassigned as 3-(4-nitrobenzylideneamino)thioacrylamide 4a on the basis of an X-ray crystal structure determination.
Synthesis, Anticonvulsant Activity, and Structure−Activity Relationships of Sodium Channel Blocking 3-Aminopyrroles
Starting from the corresponding acetophenone and glycine derivatives, a series of new 3-aminopyrroles was synthesized in few steps. Using this procedure with hydrazine and hydroxylamine instead of the glycinates provides access to S-aminopyrazoles and 5-amino-1,2-oxazoles. The various derivatives were tested for anticonvulsant activity in a variety of test models. Several compounds exhibit considerable activity with a remarkable lack of neurotoxicity. 4-(4-Bromophenyl)-3-morpholinopyrrole-2-carboxylic acid methyl ester, 3, proved to be the most active compound. It was protective in the maximal electroshock seizure (MES) test in rats with an oral ED50 of 2.5 mg/kg with no neurotoxicity noted at doses up to 500 mg/kg. Compound 3 blocks sodium channels in a frequency-dependent manner. The essential structural features which could be responsible for an interaction with an active site of the voltage-dependent sodium channel are established within a suggested pharmacophore model.