Catalytic Addition of Fluorinated Benzoic Acids to Butadiene

Abstract

The rhodium‐catalyzed addition of polyfluorobenzoic acids to butadiene led to a range of branched and linear allylic esters, with preference for the formation of the branched isomer. This method provided branched fluorinated esters in an atom‐economical catalytic addition reaction. The observation that the yield of the addition product depended on the acidity of the starting acid led to the hypothesis that the addition reaction was reversible and thus thermodynamically controlled. Deuterium‐labeling and crossover experiments supported this hypothesis. Ultimately, the dependence of yield on the pKa as reported in this paper may help to guide approaches to high‐yielding additions of acids to dienes.