Reaction of 4,6-dimethoxy-3-methylindole with aromatic aldehydes: A simple synthesis of calix[3]indoles

2,7:2,7:2,7-Linked calix[3]indoles (3a-d) have been prepared by the reaction of 4,6-dimethoxy-3-methylindole (1) and benzaldehydes with phosphoryl chloride or by a direct reaction of di(4,6-dimethoxy-3-methylindol-2-yl) phenylmethanes (2a-d) with phosphoryl chloride. An X-ray crystal structure determination of the macrocycle (3d) is reported. 4,6-Dimethoxy-3-methylindolemethanols (9) and (10) were prepared and reacted with phosphoryl chloride to study the mechanism of formation of the macrocycle.