Mechanochemical Metal-Free Synthesis of 3-Arylindenones via Unprecedented Aryl Swapping

A triflic anhydride-induced annulation of benzoic acids bearing electron-withdrawing groups with arylalkynes leading to diverse 3-arylindenones via an unprecedented aryl swapping pathway under an air atmosphere and ball-milling conditions has been disclosed.Most of the obtained 3-arylindenones are fluorine-containing compounds.The present mechanochemical protocol employs easily available and inexpensive benzoic acids,which unexpectedly undergo aryl swapping with arylalkynes and serve as the source of the 3-aryl group.The current mechanochemical methodology shows advantages including no requirement of transition-metal catalysts,ambient conditions and excellent regioselectivity for the rearrangement products,providing expedient access to 3-arylindenones containing functional groups such as F,Cl,Br,CF3,OCF3,SCF3,OAc,Ac,CO_(2)Et or NO_(2).