Enantioselective Synthesis of Natural Epoxyquinoids

Natural products play an important role as a source not only of potential therapeutic drugs but also of starting materials for semisynthetic new medicines. The epoxyquinoid family, composed by cyclohexane epoxides and related structures, exhibit these characteristics without doubt. Since 2004, significant efforts have been devoted to the stereocontrolled synthesis of these molecules with different and interesting strategies. More than 50 works on this field have been published during this period of time. In addition, many of these polyoxygenated cyclohexenoids exhibit diverse and impressive bioactive shapes. This review aims to analyze the recent advances in the enantioselective processes that have been performed for the total syntheses of these target molecules. It includes a wide range of methodologies for the introduction of chirality either enzymatic or chemical ones. This summarizes microbial preparation of starting materials, lipase kinetic resolutions, use of compounds from the chiral pool, use of chiral auxiliaries and asymmetric catalysis. In a special section, syntheses of scyphostatin are also included.