Synthesis of Calix[4]arenes with Four Different "Lower Rim" Substituents.

Calix[4]arenes with four different "lower rim" substituents were synthesized following six-step sequences. The first alkyl group (R(1)) was introduced using R(1)X and CH(3)ONa, and then reaction with R(2)X and K(2)CO(3) led to the introduction of a second alkyl group (R(2)) at the 3-position. Benzoate was introduced as a protecting group at the 1,3-O-disubstituent stage and was removed under basic conditions after the incorporation of the third alkyl group (R(3)) with R(3)X and NaH. The final alkyl group (R(4)) was introduced with R(4)X and NaH to give the chiral title compounds.