Convenient route to super-expanded calixpyrroles: Synthesis of calix[n]furano[m]pyrroles (n=3, 4, 6, 8 and m=2, 4)

[GRAPHICS] meso-Alkylporphyrinogen-like cyclic oligomers containing furans and pyrrole s have been synthesized by "3 + 2" and "4 + 2" approaches. Condensation of 5,5,10,10,15,15-hexaethyl-21,22-dioxatetrapyrromethane with 2,5-bis[(alpha- hydroxy-alpha,alpha-dimethyl)furan] resulted in the formation of cyclic hex amer and cyclic dodcamer. Effects of catalysts, temperature, inorganic addi tives, solvent, and reaction concentration were examined.