Synthesis of (±)‐4‐Demethoxydaunomycinone by Double <i>Diels‐Alder</i> Additions to 2, 3, 5, 6‐Tetramethylidene‐7‐oxanorbornane

Abstract

Abstract Sequential Diels‐Alder additions of methylvinyl ketone and dehydrobenzene to 2, 3, 5, 6‐tetramethylidene‐7‐oxanorbornane (4) yielded the (5, 12‐epoxy‐1, 2, 3, 4, 5, 6, 11, 12‐octahydro‐2‐naphtacenyl) methyl ketone (10) which, in few steps was oxidized to a precursos of (±)‐4‐demethoxydaunomycinone. The preparations of two precursors of anthracyclinones, the (5‐acetoxy‐) and (12‐acetoxy‐1, 2, 3, 4‐tetrahydro‐2‐naphtacenyl) methyl ketones (14, 15) are presented. The synthesis of 6, 13‐epoxy‐6, 13‐dihydropentacene (8) is also reported.