Regioselective Synthesis of 1,2- and 1,3-Bridged Calixcrowns. What Are the Factors Controlling the Regioselectivity?

Article abstract of DOI:10.1246/cl.1994.469

The product distribution in the synthesis of calix<4>crowns from calix<4>arene-25,26,27,28-tetrol and 3,6-dioxaoctane-1,8-ditosylate was investigated in detail. It was shown that the 1,2- vs. 1,3-bridging regioselectivity is governed by the basicity and the metal cation of the used base. The findings enable us to regioselectively synthesize desired calix<4>crowns in good yields, which has been believed to be too difficult to control.