Asymmetric Synthesis of the <i>cis</i>- and <i>trans</i>-3,4-Dihydro-2,4,8-trihydroxynaphthalen-1(2<i>H</i>)-ones

A short and efficient protocol for the asymmetric synthesis of <i>cis</i>- and <i>trans</i>-3,4-dihydro-2,4,8-trihydroxynaphthalen-1(2<i>H</i>)-one (<b>1</b> and <b>2</b>, resp.) is described, with a phthalide annulation as the key step. Introduction of a OH substituent at position 2 was performed by <i>Sharpless</i> dihydroxylation of a silyl enol ether or by means of an <i>N</i>-sulfonyloxaziridine. The absolute configuration of each isomer was determined via <i>Mosher</i>-ester derivatives. By comparison with previously recorded CD spectra of our natural sample, we established that the natural <i>trans</i>- and <i>cis</i>-isomers from <i>Ceratocystis fimbriata</i> sp. <i>platani</i> were the (-)-(2<i>S</i>,4<i>S</i>)-isomer (-)-<b>2</b> and the (+)-(2<i>S</i>,4<i>R</i>)-isomer (+)-<b>1</b>, respectively.