One-pot Selective Formylation and Claisen Rearrangement on Calix[4]arenes

Abstract

A versatile synthon with formyl and allyl groups at the upper rim of calix[4]arene has been synthesized in two steps. Selective formylation of 25,27-diallyloxy-26,28-dihydroxycalix[4]arene, along with the Claisen rearrangement of the allyl groups, was achieved by reaction with hexamethylenetetraamine (hexamine) in glacial acetic acid. A control reaction of the dipropyl analogue shows that the selective formylation takes place independently of the Claisen rearrangement. The crystal structure of the dimethylacetal derivative of 5,17-diformyl-11,23-diallylcalix[4]arene is reported.

25-Allyloxy-5,11,17,23-tetra-tert-butyl-26,27,28-trihydroxycalix[4]arene chloroform disolvate

“…In particular, the substitution serves to freeze the calix framework conformationally, to improve the inclusion selectivity or to act as an effective linkage group for the generation of complex calix [4]arene constructions (Mandolini & Ungaro, 2000;Vicens & Harrowfield, 2007). In this respect, lower rim-site substituents featuring an olefinic group have proven very useful (Gutsche et al, 1985;Akine et al, 2001;Vocanson et al, 2003;Shiao et al, 2006;Mocerino et al, 2006).…”