To evaluate the role during the reaction of the triflic acid that can be generated during the reaction from the catalyst counterion, a control reaction between 2a and 3a in the presence of 5 mol% TfOH were conducted. The reaction yielded an inseparable mixtures of products, thus suggesting triflic acid is not directly responsible for the observed reactivity. Furthermore, addition of 5 mol% of non-nucleophilic base 2,6di-tertbutylpyridine (DTBP), significantly slows down the reaction (only 28% conversion after 12 h vs 83% at 6 h). These studies suggest a Bronsted acid type activation via H + transfer, which is scavenged by DTBP in this case.