25,26-Dialkoxycalix[4]arenes. Part 1: 25-Alkoxy-26,27-diacetoxy route

Abstract

Acetylation of calix[4]arene 1,3-dialkyl ethers yielded the corresponding monoacetates. The 1H NMR spectral analysis indicated that the products’ alkoxy moieties were ‘rotation restricted’. Acylation of calix[4]arene monoalkyl ethers with acetyl chloride yielded monoacetates and/or 2,3-diacetates in different reaction conditions. A simple recrystallization process was able to isolate 2,3-diacetates in good yield. The 1H NMR spectra of the diacetylated products indicated that those compounds also possessed the ‘rotation restricted’ alkoxy moieties. In the presence of K 2CO 3 as reaction base, alkylation of 2,3-diacetates produced the acetyl-migrated 1,3-dialkyloxy derivatives. Basic hydrolysis of the acetyl-migrated compounds yielded the known 1,3-dialkoxycalix[4]arenes. In the presence of NaH as reaction base, 2,3-diacetates were alkylated with and without the acetyl-migration. For the highly reactive benzyl bromide and allyl bromide, the majority of alkylation proceeded without acetyl-migration. In the other alkyl halides, the products were the acetyl-migrated 1,3-dialkoxy derivatives along with less than one-fourth the amount of non-migrated 1,2-dialkoxy derivatives.