A stereoconvergent synthesis of (+)-4-demethoxydaunomycin
Abstract
Sharpless kinetic asymmetric epoxidation on (±)-2-(1-hydroxyethyl)-5,8-dimethoxy -3,4-dihydronaphthalene [(8)] followed by LiAlH4 reduction gave R-(–)-2-(S-1-hydroxyethyl)-2-hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene [(–)-(10)] and the undesired antipode: the former was converted into R-(–)-2-acetyl-2-hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene [R-(–)-(3)] while the latter was epimerized and recycled.