Reversal phenomenon of reaction velocity in a mixed reaction system: Silylations between simple alcohols and alpha- or beta-hydroxyketones using anilinosilanes and catalytic TBAF agent

摘要

We encountered a unique phenomenon of reaction velocity reversal during the silylation between mixed simple alcohols (A; AOH) and alpha- or beta-hydroxyketones (B; BOH). The present reaction system using anilinosilanes 1a [PhNH(TMS)] (TMS-A) and 1b [PhNH(TES)] (TES-A) with the catalytic TBAF (0.02 equiv) reagent showed that the order of silylation-velocity between the independent system and the mixed system was distinctively reversed [nu(A) > nu(B) approximate to nu(B(mix)) > nu(A(mix))]. A total of seven examples indicate its high generality: AOH = linalool, 3-octanol; BOH = valeroin, benzoin, 5-hydroxy-4-methyl-3-undecanone. Time-dependent IR spectroscopy analysis rationally supported this speculation.