Practical synthesis of chiral 9,9′-spirobixanthene-1,1′-diol

Abstract

A concise four-step synthesis of 9,9'-spirobixanthene-1,1'-diol is reported, featuring a practical preparation at large scale without the use of column chromatography purification. Co-crystallization with N-benzylcinchonidinium chloride and N-benzylquininium chloride rendered the optically pure product in both enantiomers.