Total synthesis of zaragozic acid A (squalestatin S1): synthesis of the relay compound

A method for the synthesis of dimethyl acetal tri-tert-butyl ester was developed based on the rearrangement of a suitably constructed hexose to a 1,6-anhydrofuranose. The synthetic strategy involves the formation of an essential 1,6-anhydrofuranose core of the zaragozic acids which was converted to the C1 side chain and three carboxy groups. Furthermore, the final product of the synthetic process was identical to the material prepared by the degradation of zaragozic acid.