Regioselective mercuration of calix[4]arene in the partial cone conformation enabled a straightforward access to a novel type of inherently chiral calixarenes with a highly distorted cavity.
The hydroxide ion catalysed phosphorylation of p-t- butylcalix [4] arene by diethyl chlorophosphate under heterogeneous conditions shows a marked sensitivity to the nature of the phase transfer catalyst used. Thus, substitution of tetraethylammonium bromide for the tetrabutylammonium bromide prescribed for the synthesis of the calixarene tetraphosphate leads to a major reaction product becoming a bis (phosphate) in which the calixarene binds as a unidentate ligand to one phosphorus and as a bidentate ligand to the other. An X-ray crystal structure analysis on this new compound shows the calixarene to adopt a somewhat distorted 'cone' conformation with an unusual orientation of one of the t-butyl substituents into the cone cavity. It also reveals that a significant diastereoselectivity must operate in the formation reaction. The only other reaction product detected in this system appears to be the calixarene tetraphosphate in a partial cone conformation.
The synthesis and room-temperature single-crystal X-ray structural characterization of 25,27-
di(allyloxy)-5,17-di-t-butyl-26,28-dimethoxycalix[4]arene are recorded. Crystals are monoclinic, C2/c, a 29.089(5), b 10.742(2), c 26.218(8) Ǻ, β 110.09(2)°, Z = 8; the structure was refined to a residual of 0.065 for 4103 independent 'observed' [I > 3σ(I)] reflections. The flattened partial cone conformation of the molecule allows inclusion of one of the methoxy substituents in a way which could block inclusion of a metal ion capable of polyhapto aromatic coordination and which may therefore explain why solution n.m.r. measurements indicate that silver(I) binds to the pendent alkene groups.
A research has been conducted to synthesize thiomethylated-C-4-methoxyphenylcalix[4]resorcinarene using fennel oil as a starting material. The synthesis was carried out in four steps i.e. (1) oxidation of anethole to yield p-anisaldehyde, (2) HCl-catalyzed condensation of p-anisaldehyde with resorcinol, (3) chloromethylation of C-4-methoxyphenylcalix[4]resorcinarene with paraformaldehyde and HCl in the presence of ZnCl2 to yield tetrakis-chloromethyl-C-4-methoxyphenylcalix[4]resorcinarene, and (4) reaction of tetrakis-chloromethyl-C-4-methoxyphenylcalix[4]resorcinarene with thiourea followed by hydrolysis with sodium hydroxide solution to yield tetrakis-thiomethyl-C-4-methoxyphenylcalix[4]resorcinarene. The prepared compounds were characterized based on melting point, FT-IR, and NMR spectrometers. According to the analysis of 1H-NMR spectrometer, C-4-methoxyphenylcalix[4]resorcinarene and tetrakis-chloromethyl-C-4-methoxyphenylcalix[4]resorcinarene were observed in the chair or flattened partial cone conformation, while tetrakis-thiomethyl-C-4-methoxyphenylcalix[4]resorcinarene tend to exist in the crown or cone conformation.
PREPARATION AND CHARACTERIZATION OF BONDED-PHASES OF CALIXARENE-SULFONYL-CARBOXAMIDES IN PARTIAL-CONE CONFORMATION FOR DETERMINATION OF SALBUTAMOL IN LIVESTOCK BY NANO-MEDIATED BONDED-PHASES: NANO-BASKETS OF CALIXARENE IN PARTIAL-CONE CONFORMATION