H3PW12O40-Catalysed Alkylation of Arenes and Diveratrylmethanes: Convenient Routes to Triarylmethanes and to Symmetrical and Unsymmetrical 9,10-Diaryl-2,3,6,7-tetramethoxyanthracenes

An efficient method for the synthesis of triarylmethanes and difurylarylmethanes through solventless reactions between aldehydes and arenes in the presence of H3PW12O40 as a reusable catalyst under thermal and microwave irradiation conditions has been developed. H3PW12O40-catalysed one-pot consecutive Friedel-Crafts reactions between veratrole and aldehydes were also applied as a convenient protocol for the preparation of symmetrical 9,10-diaryl-2,3,6,7-tetramethoxyanthracenes. The conversion of aldehydes into their corresponding acylals in the presence of H3PW12O40 and the one-pot reactions of diveratrylmethanes with these acylals were also used for the synthesis of symmetrical and unsymmetrical 9,10-diaryl-2,3,6,7-tetramethoxyanthracenes.