Resorcarene trimers

Figure 6.51 Synthesis of a trimeric carcerand from a resorcarene trimer precursor.76...

Work by Paul Beer et al. in Oxford on dithiocarbamate-functionalised resorcarenes has resulted in resorcarene trimers termed molecular loops and molecular tetrahedra composed of four resorcarene units. The molecular loops (pyridine-capped Cd(II) and Zn(II) complexes) can bind C60 which fits neatly into the 16.4 A wide central cavity.35 The slightly larger tetrahedral tetramer which has a 19.4 A edge length, compared to 19.1 A for the loop, is bridged by square planar copper(III) ions, a very unusual oxidation state of copper that is obtained from iodine oxidation of an intermediate copper(II) complex. The solid-state structures of examples of the loop and tetrahedron are shown in Figure 10.35. 

Cyclic products were not obtained with electron-withdrawing snbstitnents like NO2 or COOFI in the 2-position °. Flowever, cyclic tetramers of the resorcarene type (27) were recently prepared in yields np to 70% from 2,6-dihydroxypyridine and aliphatic or aromatic aldehydes by HCl-catalysed condensation in glycol monoisopropyl ether . Attempts to prepare resorcarene-like macrocycles with 2,7-dihydroxynaphthalene nnits failed. A 3,5-connected trimer was isolated in 23% yield from the condensation of 3-hydroxymethyl-2,7-dimethoxy-l,8-dipropylnaphthalene . Monoethers of resorcinol (3-alkoxyphenols) react with aldehydes in the presence of Lewis acids to form C4-symmetrical compounds 28 (as confirmed by X-ray analysis for one example) in high yield (80%) . ... 

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