CYCLIC ESTERS OF CALIXARENES WITH PHTHALIC-ACID AND PYROMELLITIC ACIDSYNTHESIS AND X-RAY MOLECULAR-STRUCTURES

The reaction of phthaloyl dichloride with tert-butylcalix[4]-, calix[5 ]- and calix[6]-arene has been studied. While the 1,2-bridged macrocyc lic ester is the main product in the case of calix[4]- and calix[6]-ar ene. the intramolecular bridging of the calix[5]arene occurs mainly in the 1,3-position. The derivatives of calix[4]- and calix[6]-arene cou ld be further O-alkylated and the ester bonds may be easily hydrolysed in these derivatives. 1,2-Singly bridged derivatives of calix[4]- and calix[6]-arene were also obtained with ClCH2Br. Reaction of tert-buty lcalix[4] arene with pyromellitic acid tetrachloride reads to the form ation of a new double calixarene. The structures of two cyclic esters have been determined by X-ray crystallography. Crystals of compound 6c .0.2 MeOH are triclinic. space group P $$($) over bar 1, with two mole cules in a unit cell of dimensions a =10.9292(6), b =15.0534(10), c =1 6.8534(14) Angstrom, alpha = 94.195(6)degrees, beta = 90.044(6)degrees , gamma = 100.171(5)degrees, R = 0.075 for 2187 observed reflections. Crystals of compound 8.0.83 C7H8.0.38 C6H14 are monoclinic, space grou p P2(1)/n, with 4 molecules in a unit cell of dimensions a = 14.5554(1 3), b = 35.3802(24), c = 15.0160(12) Angstrom, beta = 99.782(7)degrees , R = 0.072 for 4028 observed reflections. The phthaloyl residue is en clathrated in the molecular cavity of a neighbouring calix[6]arene in a self-inclusion process resulting from C-H...pi(arene) hydrogen-bondi ng interactions.