One-step synthesis of p-tert-butylcalix[6]-1,4-2,5-biscrown-4 and its tosyloxyethoxyethylate derivative

p-tert-Butylcalix[6]-1,4-2,5-biscrown-4 (2a) is a typical member of the family of calix[6]biscrowns. In the literature, 2a has been prepared in a two-step procedure, the total yield being less than 26.4% and the work-up was troublesome. Herein we wish to report an improved method to synthesize such a compound in one step with a yield of up to 63%. Furthermore, this method could provide a monosubstituted p-tert-butylcalix[6]-1,4-crown-4 (2b) as a by-product. Varying the reaction conditions, we could obtain 2b as a main product with a 48% yield.