Reductive Amination of Ethynylpyridines with Sodium Cyanoborohydride
In order to investigate the structure-activity relationship of betahistine derivatives, a general synthesis of methylated 2-(2-methylaminoethyl)pyridines was developed based on the addition of methylamine hydrochloride to methylated 2-ethynylpyridines under reductive conditions.In addition, the scope and limitations of the reductive addition were briefly examined.For example, the reaction proceeded smoothly with p-nitrophenylacetylene, whereas phenylacetylene itself did not react with methylamine.Keywords - ethynylpyridine; sodium cyanoborohydride; reductive amination; betahistine; palladium-catalyzed reaction; ethyl pyridineacetate; 2-(2-pyridyl)ethylamine