Bi(OTf)3-catalysed domino Friedel-Crafts alkylation of arenes with aldehydes: An upgraded method for efficient synthesis of triarylmethanes and anthracene derivatives

Abstract

A variety of novel triarylmethanes including bis-(dihexyloxyphenyl)arylmethanes and diveratrylmethanes were prepared by the domino Friedel-Crafts alkylation of arenes with aldehydes catalysed by Bi(OTf)3. The reaction of veratrole with aromatic dialdehydes afforded different results based on the molar ratio of reactants and the nature of aromatic dialdehydes. Bi(OTf)3/O2is shown to be a highly efficient reagent system to promote the tandem three-step reaction of acylals with bis-(dihexyloxyphenyl)arylmethanes or diveratrylmethanes for the preparation of 9,10-disubstituted-2,3,6,7-tetraalkoxyanthracenes. The substrate scope, the simplicity of the reactions and work-up processes, besides a significant improvement in the yields and reaction times are valuable advantages of these methods, which represent a new and powerful route to multi-substituted anthracenes. © 2016 Elsevier Ltd.