Convenient synthesis of triarylmethanes and 9,10-diarylanthracenes by alkylation of arenes with aromatic aldehydes using acetyl bromide and ZnBr2/SiO2

Reaction of electron-rich arenes with acetyl bromide and aldehydes in the presence of silica gel-supported zinc bromide was carried out in benzene to give selectively the corresponding triarylmethanes or 9,10-diarylanthracenes in high yields depending upon the ratio of an arene and an aldehyde. The mild conditions employed are especially noteworthy.