Grignard Reactions in Cyclopentyl Methyl Ether (CPME)

We undertook a systematic study of Grignard reactions using cyclopentyl methyl ether (CPME) as a reaction solvent. Diisobutylaluminum hydride was found to be the most appropriate activator of magnesium and a number of Grignard reagents could be prepared as homogeneous or heterogeneous solutions in CPME. The CPME used in the Grignard reaction was efficiently recycled without affecting the reaction yield of the second experiment. GC–MS analysis of the recovered solvent revealed that CPME was stable under the Grignard conditions. Some of the Grignard reagents in CPME were stable for at least several months and therefore these solutions could replace existing commercial reagents. Tramadol hydrochloride, an analgesic that is used worldwide, and tamoxifen, an anti‐estrogenic drug for estrogen‐receptor‐positive breast cancer were synthesized using Grignard reactions in CPME. [Open Access]