Easy and Selective Method for the Synthesis of Various Mono-<i>O</i>-functionalized Calix[4]arenes: De-<i>O</i>-functionalization Using TiCl<sub>4</sub>
作者:Joackim Bois、Jeff Espinas、Ulrich Darbost、Caroline Felix、Christian Duchamp、Denis Bouchu、Mostafa Taoufik、Isabelle Bonnamour
DOI:10.1021/jo101319s
日期:2010.11.19
An efficient and selective method for the monofunctionalization of p-tert-butylcalix[4]arene is described A mono-de-O-functionalization of disubstituted p-tert-butylcalix[4]arenes using titanium tetrachloride was developed to synthesize a series of monosubstituted p-tert-butylcalix[4]arenes with the pendant functions being ethoxycarbonylmethyloxy, 3-ethoxycarbonylpropyloxy, cyanomethyloxy, 3-cyanopropyloxy, 4-bromobutyloxy, 3-hydroxypropyloxy, propyloxy, 2-methylpropyloxy, 3-butynyloxy, and 3-cyanopropyloxy groups The reaction mechanism of the formation of 5,11,17,23-tetra-tert-butyl-26,27,28-trihydroxy-25-(3-ethoxycarbonylpropyloxy) calix[4]arene was studied by H-1 NMR and GC/mass spectroscopy monitoring Reaction of TiCl4 with the disubstituted p-tert-butylcalix[4]arene produced the corresponding dioxocalix[4]arene titanium dichloride complex, which undergoes elimination of ethyl 4-chlorobutyrate, leading to a trioxocalix[4]arene titanium dichloride complex and to monosubstituted calix[4]arene after hydrolysis These two complexes were also synthesized, isolated, and fully characterized