Synthetic Exploration of Oxacalix[2]arene[2]quinazolines

Abstract

Oxacalix[2]arene[2]quinazoline macrocycles were prepared in good yields, as mixtures of syn and anti isomers, through nucleophilic aromatic substitution cyclocondensation reactions of 2,4-dichloroquinazolines and m-dihydroxybenzenes. The macrocyclization conditions were optimized and the isomeric ratio was investigated by means of one-step and fragment-coupling approaches. The oxacalixarene substitution pattern could easily be varied by altering the dichloroquinazolinyl biselectrophilic and dihydroxyaryl bisnucleophilic building blocks. The solid-state (1,3-alternate) conformational behavior and the oxacalix[4]arene cavity size were explored by X-ray diffraction studies.