Easy and selective method for the synthesis of various mono-O-functionalized calix[4]arenes: de-O-functionalization using TiCl4.
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 (1)H 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.
Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Equipe CSAp, CNRS, UMR 5246, Université de Lyon, Lyon, Université Lyon 1, Villeurbanne, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France.
Joackim
J
Bois
Jeff
J
Espinas
Ulrich
U
Darbost
Caroline
C
Felix
Christian
C
Duchamp
Denis
D
Bouchu
Mostafa
M
Taoufik
Isabelle
I
Bonnamour