Synthesis of new resorcinarenes under alkaline conditions

The preparation of functionalized resorcinarenes is described. Thus, 2-nitroresorcinol (=2-nitrobenzene-1,2-diol), 2-acetylresorcinol (=1-(2,6-dihydroxyphenyl)ethanone), and 2,6-dihydroxybenzoic acid were treated with formaldehyde in alkaline medium to give the corresponding resorcinarenes 1-3 (Scheme 1). This method is also applicable for resorcinol (= benzene-1,3-diol) itself, but the yields are poorer. In this case, the molecule formed is the simplest resorcinarene 4 on which a number of substituents can be inserted between the two OH groups. Thus. bromation of 4 yields 5 (Scheme 2). Some properties and conformations of these new products are discussed, and the X-ray crystal structures of the nitro and bromo compounds 1 and 5, respectively, are presented.