Synthesis and optical resolution of naphthalene-containing inherently chiral calix[4]arenes derived by intramolecular ring closure or stapling of proximal phenyl units
New methods for the preparation of inherently chiral calix[4]arenes have been developed. The molecular asymmetry in these calix[4]arenes is created by an asymmetrical disposition of naphthalene rings on the upper rim. In compound 1, monoformylcalix[4]arene 5 was transformed into naphthalene-containing calix[4]arene by ring closure. In compound 2, p-chloromethyl groups are intramolecularly cross-linked