O ‐Benzylation of Carboxylic Acids Using 2,4,6‐Tris(benzyloxy)‐1,3,5‐triazine (TriBOT) under Acidic or Thermal Conditions

Two methods for the synthesis of benzyl esters from carboxylic acids using the O ‐benzylating reagent 2,4,6‐tris(benzyloxy)‐1,3,5‐triazine (TriBOT) have been developed. The reactions were conducted either in the presence of a catalytic amount of TfOH at room temperature (acidic conditions) or in the absence of TfOH at 180–230 °C (thermal conditions). Interestingly, the O ‐benzylation of hydroxy carboxylic acids under the two conditions afforded different products: The dibenzylated product under acidic conditions and the hydroxy ester under thermal conditions. In addition to these results, other evidence indicated that the former reaction proceeds through an S N 1‐type mechanism, and the latter by an S N 2‐type mechanism.