Structure–activity relationships in the inhibition of monoamine oxidase B by 1-methyl-3-phenylpyrroles
摘要:
Methyl-3-phenyl-3-pyrrolines are structural analogues of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and like MPTP are selective substrates of monoamine oxidase B (MAO-B). As part of an ongoing investigation into the substrate properties of various 1-methyl-3-phenyl-3-pyrrolinyl derivatives, it is shown in the present study that their respective MAO-B catalyzed oxidation products act as reversible competitive inhibitors of the enzyme. The most potent inhibitor among the oxidation products considered was 1-methyl-3-(4-trifluoromethylphenyl)pyrrole with an enzyme-inhibitor dissociation constant (K-i value) of 1.30 mu M. The least potent inhibitor was found to be 1-methyl-3-phenylpyrrole with a K-i value of 118 mu M. The results of an SAR study established that the potency of MAO-B inhibition by the 1-methyl-3-phenylpyrrolyl derivatives examined here is dependent on the Taft steric parameter (E-s) and Swain-Lupton electronic constant (F) of the substituents attached to C-4 of the phenyl ring. Electron-withdrawing substituents with a large degree of steric bulkiness appear to enhance inhibition potency. Potency was also found to vary with the substituents at C-3, again with E-s and F being the principal substituent descriptors. (C) 2007 Elsevier Ltd. All rights reserved.
New Synthetic Routes to 3-, 5-, and 6-Aryl-2-chloropyridines
摘要:
The efficient synthesis of 3-, 5-, and 6-aryl-2-chloropyridines via the facile preparation of 5-(dimethyamino)aryl-substituted pentadienyl nitriles and cyclization with hydro chloric acid is described. This approach allows for the introduction of other electron-withdrawing substituents on the pyridine ring as well as the preparation of the desired unsubstituted arylpyridines. Some differences in the rates of cyclization of the pentadienyl nitriles as well as the yields of chloropyridines were observed that depended on the position and degree of substitution in the aryl substituent. The arylpentadienyl nitriles 5 and 6 could also be converted directly into the corresponding 2-aminopyridines.