Functionalization of the methylene groups of p-tert-butylcalix[4]arene: S-C, N-C, and C-C bond formation.
Reaction of the calixarene derivative 7 with two exocyclic double bonds with carbon-, nitrogen-, oxygen-, or sulfur-containing nucleophiles afforded bis(spirodienone) derivatives substituted at two opposite methylene groups in a trans fashion. LiAlH(4) reduction of the bis(spirodienone) derivatives with two methylenes functionalized by thiomethoxy, diethyl malonate, or anilino substituents yielded trans methylene-substituted calix[4]arenes. Upon standing in solution, the calixarene derivative incorporating SMe groups on the bridges underwent trans right harpoon over left harpoon cis isomerization. An equilibration study performed on this calixarene derivative (tetrachloroethane-d(2), 430 K) indicated that the cis isomer is the form of lower free energy.
Simaan
Samah
S
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Agbaria
Kasim
K
Biali
Silvio E
SE