Chemically modified calix[4]arenes. Regioselective synthesis of 1,3-(distal) derivatives and related compounds. X-Ray crystal structure of a diphenol-dinitrile

摘要: p-tert-Butylcalix[4]arene has been chemically modified in a regioselective manner at the 1,3-(distal) phenolic groups of lower rim using electrophiles such as ethyl bromoacetate, chloroacetone, bromopinacolone, chloroacetonitrile, and prop-2-ynyl bromide. X-Ray diffraction analysis one these 1,3-derivatives reveals that it exists highly distorted cone conformation. Crystals dinitrile 7 are triclinic, space group P, with two molecules cell dimensions a= 13.191 (3), b= 16.755(3), c= 10.424(1)A; α= 100.32(1), β= 93.23(1), γ= 84.89(2)°. The structure was solved by direct methods refined full-matrix least squares calculations; R= 0.066 for 4155 observed reflections. rings (A C) tilted (interplanar angle 102.3°) so to place hydroxy inside cavity, whereas B D bearing OCH2CN moieties almost parallel each other 13.3°). This arrangement allows relatively facile intramolecular hydrogen bond formation between proximal ether functional [O(H)⋯ O 2.941(3) 2.903(3)A]. These products useful precursors 1,3-disubstituted derivatives including double calixarenes variety tetrasubstituted calix[4]arenes dual functionality on rim.