希土類及びHfトリフラート触媒を用いたベンジルアルコールからのベンジルカチオン生成と、ケトンエノール誘導体のベンジル化への応用

抄録

We have developed a highly effective secondary benzylation system for aromatic nucleophiles using benzyl alcohols catalyzed by rare-earth metal and hafnium triflate in nitromethane. The benzylation proceeds smoothly even in the presence of water. In this presentation, we will report a convenient method for α-secondary benzylation of enolacetates as a nucleophile. Various enol acetates prepared from methyl or cyclic ketone underwent sec-benzylation with sec-bezyl alcohols in the presence of 0.5-1 mol% of La, Yb, Sc, and Hf triflates. Addition of Mg(ClO₄)₂ increased the yield of the benzylation. Various 1-phenylethanols bearing a functional group (e.g, hydroxy, acetoxy, benzyloxy, tert-butyldimethylsilyloxy) were able to be used for the benzylation.

fig.1