The organometallic route to benzylamine type monoamine oxidase inhibitors

N-Methyl-N-(2-propynyl)piperonylamine can be simultaneously lithiated at the terminal acetylenic and at that arom. position which is flanked by both the side chain and an oxygen atom. Under carefully established conditions, the metal occupying the latter ortho position can be selectively replaced by an electrophile. In general, it is however more convenient and also more efficacious to protect the acetylenic site by silylation. Then lithium may be introduced into the double-ortho position either by hydrogen/metal or by halogen/metal exchange, using 2-bromo-N-methyl-N-[(3-trimethylsilyl)-2-propynyl]piperonylamine as the starting material in the latter case. One of the new products, i.e., 4-bromo-N-methyl-N-(2-propynyl)-1,3-benzodioxole-5-methanamine (piperonal deriv.), proved to be a strong monoamine oxidase (MAO) inhibitor. [on SciFinder (R)]