25,26-Dialkoxycalix[4]arenes. Part 2: 1-Alkoxy-3-benzoyloxy route

Abstract

Benzoylation of calix[4]arene monoalkyl ethers with benzoyl chloride yielded the corresponding 3-benzoates and/or 2,3-dibenzoates in different reaction conditions. A simple recrystallization process was able to isolate the 3-benzoates in good yield. In the presence of NaH as reaction base, the 1-alkoxy-3-benzoyloxycalixarenes were alkylated with active alkyl halides at proximal position and yielded the corresponding 1,2-dialkoxy derivatives. Basic hydrolysis of compounds afforded the expected 25,26-dialkoxycalix[4]arenes. For the less active alkyl halides, alkylation of 1-alkoxy-3-benzoyloxycalix[4]arenes afforded both the 1,2-dialkoxy derivatives and the benzoyl-migrated 1,3-dialkoxy derivatives. Only the highly symmetrical 1,3-diethoxy-2-benzoyloxycalix[4]arene was able to be isolated upon the deliberate recrystallization process. After basic hydrolysis of the dialkylated crude products, 25,26-dialkoxycalix[4]arenes were chromatographic separated.