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.