Pentafluorophenylammonium triflate (PFPAT): an efficient, practical, and cost-effective catalyst for esterification, thioesterification, transesterification, and macrolactone formation

摘要

A pentafluorophenylammonium triflate (PFPAT) catalyst (1-10 mol%) efficiently promoted esterification and thioesterification between a 1:1 mixture of carboxylic acids and alcohols or thiols in good to excellent yield under mild reaction conditions. Transesterification of carboxylic esters with a slight excess of alcohols (1.5 equiv.) also proceeded using the PFPAT catalyst. The PFPAT-catalyzed 13 to 17 membered macrolactone formation of omega-hydroxycarboxylic acids was successfully performed using 10 mol% of the catalyst (total 44 examples). These catalytic condensations have advantages from the viewpoint of green chemistry. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures. The operation is quite simple, because a dehydrating system such as the Dean-Stark apparatus is not necessary.