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Grignard Reactions in Pyridinium and Phosphonium Ionic Liquids



Alkylpyridinium (10a, R = Me and 10b, R = Et) and tetraalkylphosphonium (19) ionic liquids which possess ether functionality were prepared and evaluated as solvents and co-solvents for Grignard reactions. Interestingly, reduction of the starting aldehydes to the corresponding primary alcohol was the favored pathway when reactions were conducted in pyridinium ILs 10a, b in the absence an ethereal co-solvent. However, the same reactions in the phosphonium IL 19 afforded the expected Grignard products in good yield in cases where diethyl ether was present as a co-solvent.