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.