Asymmetric Synthesis of the cis‐ and trans‐3,4‐Dihydro‐2,4,8‐trihydroxynaphthalen‐1(2H)‐ones

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