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An efficient synthesis of naturally occurring compounds isolated from Pentas longiflora, cis-3,4-dihydroxy-3,4-dihydromollugin 2, and trans-3,4-dihydroxy-3,4-dihydromollugin 3 is described. The O-protected mollugins were dihydroxylated using OsO4 to achieve the corresponding cis-dihydroxy derivatives in excellent yield. The synthesis of trans-3,4-dihydroxy-3,4-dihydromollugin was achieved using Oxone in good yield. A mechanism for the formation of cis-3,4-dihydroxymollugin acetonide from the reaction of mollugin with Oxone is proposed.

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Benzofuran derivatives R 0070Ytterbium Triflate Catalyzed Conjugate Addition of β-Ketoesters to Activated 1,4-Naphthoquinones. -The reaction is strongly sensitive to the nature of solvent and reaction time. The reaction of β-ketoesters (VI) in MeCN provides a mixture of diastereomers after 30-45 min and leads directly to the dehydrated products after 90 min. -(MUDIGANTI, N. V. S.; CLAESSENS, S.; DE KIMPE*, N.; Tetrahedron 65 (2009) 8, 1716-1723; Dep. Org. Chem., Fac. Biosci. Eng., Univ. Gent, B-9000 Gent, Belg.; Eng.) -Y. Steudel 23-105