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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.
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Yamamoto et al. (1994) studied this question.
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