Efficient Dehydration of 1-Phenylethanol to Styrene by Copper(II) and Zinc(II) Fused-Bisoxazolidine Catalysts

The air-stable copper(II) catalyst [Cu(^mesoFOX-L1)(MeCN)][OTf]₂ (2a) is prepared from a fused meso-dipyridylbisoxazolidine (^mesoFOX-L1) and CuBr₂, followed by treatment with AgOTf. The compound is a catalyst for the dehydration of 1-phenylethanol to styrene (+H₂O) in over 95% yield at 1 mol % catalyst loading. Other alcohols (benzylic, tertiary, or allylic) are also efficiently dehydrated by this catalyst. Water separation in toluene solvent is found to play an important role in the reaction. Related compounds with Zn(II) have been prepared and display reduced dehydration activity.