Synthesis of Phenyl- and Pyridyl-substituted Benzyloxybenzaldehydes by Suzuki-Miyaura Coupling Reactions

Background: Aryl-methoxybenzaldehydes substituted in various positions may serve as valuable starting materials for the synthesis of biologically active compounds. Methods: Biaryl-methoxybenzaldehydes and pyridyl-aryl-methoxybenzaldehydes were synthesized by the Suzuki-Miyaura cross-coupling reactions as intermediates of potential drug substances. Three different catalytic approaches were compared. The classical Suzuki method utilising tetrakis(triphenylphosphine)palladium and sodium ethoxide, the protocol applying palladium acetate and tri(o-tolyl)phosphine, and the method using tetrakis(triphenylphosphine)palladium and cesium carbonate, were studied. Results: The selected boronic acids were the classical phenylboronic acid, as well as 4-pyridineand 3-pyridineboronic acids. 26 New biaryl-methoxybenzaldehydes or pyridyl-phenylmethoxybenzaldehydes have been synthesized, which may be intermediates for pharmaceutically active compounds. Conclusion: The method of Anderson et al. was preferred, because it provides satisfactory results in all cases.