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.
Bois
Joackim
J
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.
Espinas
Jeff
J
Darbost
Ulrich
U
Felix
Caroline
C
Duchamp
Christian
C
Bouchu
Denis
D
Taoufik
Mostafa
M
Bonnamour
Isabelle
I