The facile and efficient preparation of pillar[n]arenes (n = 5 or 6) was achieved by cyclooligomerization of 2,5-dialkoxybenzylalcohols or 2,5-dialkoxybenzylbromides with an appropriate Lewis acid catalyst at room temperature. The mechanism for this cyclooligomerization is presumed to be a Friedel–Crafts alkylation.