Methylation of p-tert-Butylcalix[8]arene. Products Obtained in the Presence of Strong Bases.

Methylation of p-tert-butylcalix[8]arene with MeI in the presence of strong bases (NaH, BaO/Ba(OH)(2), or Cs(2)CO(3)) in THF has been investigated. Composition of the reaction mixtures differs remarkably from those obtained using weak bases and described in a preceding paper. Several previously unreported methylated products [two dimethoxy- (2(1,5) and 2(1,4)), a trimethoxy- (3(1,2,5)), a tetramethoxy- (4(1,2,3,6)), two pentamethoxy- (5(1,2,3) and 5(1,2,4)), and three hexamethoxy- (6(1,2), 6(1,3), and 6(1,4))] have been isolated. In many cases the substitution pattern was assigned unambiguously on the basis of spectroscopic evidence only, while in others chemical correlation with known compounds was required.