Stereoselective synthesis of deoxy analogues of the 3C-protease inhibitor thysanone

The synthesis of racemic 7,9-dideoxythysanone was achieved starting from allylnaphthalene via epoxidation and reduction to bromoalcohol . Subsequent lithiation of the bromide and quenching with DMF afforded lactol which underwent clean oxidative demethylation to racemic 6,8-dideoxythysanone . The synthesis of (1R,3S)-(+)-7,9-dideoxythysanone was then achieved albeit in low ee, starting from (R)-epoxide which in turn was obtained via Sharpless asymmetric dihydroxylation of allylnaphthalene . An improved asymmetric synthesis of (1S,3R)-(+)-7,9-dideoxythysanone in 72% ee was then accomplished starting from (R)-bromoalcohol which was obtained via asymmetric reduction of ketone using a modified chiral oxazaborolidine. The key ketone in turn was prepared by Wacker oxidation of allylnaphthalene .