https://academicworks.cuny.edu/qc_pubs/409/
"Triflic Acid Mediated Sequential Cyclization of ortho-Alkynylarylester" by Maciej E. Domaradzki,...
A triflic acid (TfOH) mediated sequential cyclization of ortho-alkynylarylesters and ammonium acetate (NH4OAc) was reported. The reaction took place via a...