Procedures for the selective alkylation of calix[6]arenes at the lower rim

Article abstract of DOI:10.1055/s-1993-25868

New partially alkylated calix[6]arenes have been synthesized. Depending on the conditions, mono-, 1,2-di-, 1,3-di, 1,2,3-tri-, 1,3,5-tri-, 1,2,4,5-tetra-, and 1,2,3,4,5,-pentamethylated derivatives of p-tert-butylcalix[6]arene could be obtained in moderate to good yields. Methylation or benzylation of the parent calix[6]arene showed a regioselectivity towards 1,2-di-, and 1,2,3-trisubstitution. The solid state structure of 1,2,4,5-tetrasubstituted p-tert-butylcalix[6]arene [R = O(CH₂CH₂O)₂CH₃] has been elucidated by X-ray analysis.