U-62162, a member of the manumycin family of antibiotics, has been prepared as a mixture of diastereoisomers and shown to contain a syn-hydroxy epoxide nucleus and a 1,3-syn-disposed dimethyl unit in the upper side chain; the cornerstone of the synthetic route utilises organometallic addition to a monoprotected quinone epoxide-the first time this approach has been successfully employed to prepare a manumycin antibiotic.