Novel ethynylcerium(III) reagents as efficient tools for constructing the .ALPHA.-hydroxy methyl ketone moiety of anthracyclinones.

Abstract

The title cerium(III) reagents (7-10) were found to react with 5, 8-dimethoxy-2-tetralone (11a) and 5, 12-dihydroxy-1, 2, 3, 4-tetrahydronaphthacene-2, 6, 11-trione (15) more efficiently than the corresponding lithium and magnesium reagents (3, 5, and 4, 6), giving the addition products (12a, 13a, and 17) in high yields. Hydration of these adducts readily afforded the α-hydroxy methyl ketones, 2-acetyl-5, 8-dimethoxy-1, 2, 3, 4-tetrahydro-2-naphthol (14a), and 2-acetyl-2, 5, 12-trihydroxy-1, 2, 3, 4-tetrahydronaphthacene-6, 11-dione (4-demethoxy-7-deoxydaunomycinone) (18), which are versatile synthetic intermediates for optically active 4-demethoxyanthracyclinones.