Synthesis of calix[4]arenes with four different "lower rim" substituents

Calix[4]arenes with four different "lower rim" substituents were synthesize d following six-step sequences. The first alkyl group (R-1) was introduced using R1X and CH3ONa, and then reaction with R2X and K2CO3 led to the intro duction of a second alkyl group (R-2) at the 3-position. Benzoate was intro duced as a protecting group at the 1,3-O-disubstituent stage and was remove d under basic conditions after the incorporation of the third alkyl group ( R-3) With R3X and NaH, The final alkyl group (R-4) was introduced with R4X and NaH to give the chiral title compounds.