Te~~ahedrm L.& m. Vol. 33.No. 35.pp. 5125~5128.1992 P&cd in Great Britain 00404039192 $5.00 + .OO Pergamon Ress Ltd zyxwvutsrqpon Hydrogen Bonded Calix[4]arene Aggregates Jan-Dirk van Loon, Rob G. Janssen, Willem Verboom and David N. Reinhoudt’ Laboratory of Organic Chemistry, P. 0. Box 217,750O AE Enschede, The Netherlands zyxwvutsrqponmlk Abstruct. Calix[4]arenes in a rigid cone conformation that contain selfcomplementary a-pyridone moieties at the upper rim, form aggregates in CDCl, solution, which can be denaturated by the formation of a complex with urea derivatives. Calix[4]arenesr are a well established class of compounds in supramolecular chemistry. Recently we reported the synthesis of double23 and triple’ calix[4]arenes. in which two, or three calix[4larene moieties are connected covufentfy by bridges at the lower rim. In this paper we describe preliinary results on multicalix[4]arene systems based on hydrogen-bonded interactions. CPK-models suggested that calix[4]arene in a rigid cone conformation, that contain self-complementary a-pyridone moieties4 (e.g. 4 and 7) at the upper rim, could form double calix[4]arenes by multi-hydrogen-bonded interactions. Nitration of tetrakis(2-ethoxyethoxy)calix[4]arene l5 (Chart 1) 1 R1=R2=H 2 R,=H;R,= 3 Rr=H;R,= 4 R,=H;R,= 5 R1=R2=N02 NO2 6 R,=R,=NH, ‘H chart 1 under carefully controlled conditions with acetyl &rate in CH2C12 at room temperature afforded the diametrically substituted dinitrocalix[rl]arene 5” in 3040% yield together with 20% of mononittated product 2.’ Remarkably no proximally 1.2~dinitrated products could be isolated. The reason for the regioselectivity is not known, but the result is in agreement with the observation of Pochini et aL5 that the Gross-formylation of 1 also occurs with 1,3-selectivity. The ‘H NMR spectrum of 2 shows two AB systems at 6 4.57, and 3.16. and at 6 4.47, and 3.20, that are typical for a monosubstituted calix[rl]arene in the cone conformation. 5125