Scandium triflate-catalyzed cyclocondensation of 1,3-dialkoxybenzenes with 1,3,5-trioxane. Formation of resorcin[4]arenes and confused resorcin[4]arenes

The cyclocondensation of 1,3-dialkoxybenzenes with 1,3,5-trioxane was catalyzed by Sc(OTf)3 to produce resorcin[4]arene octaalkyl ethers as the major products. In addition, 'confused' resorcin[4]arene octaalkyl ethers bearing one alkoxy group at the intra-annular position were obtained as the minor products. The variable temperature 1H NMR spectroscopy showed that the alkoxy group at the intra-annular position cannot pass through the macrocyclic annulus, indicating a rigid molecular framework. The structure of the ethoxy derivative of the confused resorcin[4]arene was determined by X-ray crystallography.