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.

空气稳定型铜(II)催化剂[Cu(mesoFOX-L1)(乙腈(MeCN))][三氟甲磺酸根(OTf)]₂（2a）由稠合内消旋二吡啶基双恶唑烷（mesoFOX-L1）与溴化铜(II)反应制备，随后经三氟甲磺酸银（AgOTf）处理得到。该化合物可作为催化剂，在催化剂负载量为1 mol%的条件下，将1-苯乙醇脱水生成苯乙烯（副产物为水），产率超过95%。苄基醇、叔醇及烯丙基醇等其他醇类也可被该催化剂高效催化脱水。研究发现，甲苯溶剂中的水分离过程对该反应具有重要作用。此外，已制备得到相关锌(II)类化合物，但其脱水活性有所降低。