Pinched-cone calix[6]arene: New synthesis of p-(1,1,3,3-tetramethylbutyl)calix[6]arene. Structure of its 1 : 3 complex with chloroform

A new method is described for the synthesis of p-(1,1,3,3-tetramethylbutyl) calix[6]arene isolated in a 30% yield. For the first time the crystal struc ture is given. The crystals are monoclinic, space group C2/c, a = 24.144(5) Angstrom, b = 14.093(3) Angstrom, c = 26.972(5) Angstrom, beta = 93.36(3)d egrees, V = 9162(3) Angstrom (3), Z = 4. The macrocycle with C2 symmetry pr esents the pinched-cone conformation. It crystallizes with three chloroform molecules, two of them are positioned in the cones shaped by the phenol mo ieties; the third chloroform is located in the cavity near the hydroxyl gro ups; this solvent molecule is disordered around the 2 axis. The packing of the complex is described.