Synthesis and structure characterization of unsymmetrical oxacalix[2]benzene[2]pyrazines

The synthesis of two unsymmetrically linked oxacalix[2]benzene[2]pyrazines (1 and 2) is described. X-ray single crystal structure analysis revealed a highly distorted 1,3-alternate conformation of compound 1 (containing ortho- and meta-diphenol components) and a distorted boat conformation of compound 2 (containing meta- and para-diphenol components). Oxacalix[2]benzene[2]pyrazine containing both ortho- and para-diphenol components was not obtained via similar synthetic strategy. (C) 2009 Elsevier Ltd. All rights reserved.