Sintese de clerodanos contendo unidade hidroxibutenolida a partir do acido (+)- hardwickiico

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In this work we describe the syntheses of two new clerodanes containing the hydroxybutenolide moiety, 16-hydroxycleroda-4(18), 13-dien-16, 15-olide and 15-hydroxycleroda-4(18), 13-dien-16, 15-olide and the lactone cleroda-4(18), 13-dien-16,15 olide, starting from (+)-hardwiickic acid. As study toward the syntheses of 3-16-dihydroxycleroda-4(18),13-dien-16, 15-olide and 4a-16-dihydroxyclerod-13-en-16, 15-olide and the attainment of some sub-products is also described. Our interest for the synthesis of compounds containing the hydroxybutenolide unit is due to the fact that in recent years literature has reported the isolation and synthesis of some compounds containing this structural feature that presented interesting biological activity. The (+)-hardwiickic acid, one of the principal constituents of commercial copaiba oil, was isolated as its methyl ester after esterification with dimethyl sulfate and purification on a silica gel column. Reduction of (+)-methyl hardwickiate with Na° in n-propanol followed by esterification with diazomethane and reduction with LiAIH4, furnished the correspondent saturated alcohol in 59% yeld. Dehydration of this alcohol led to the correspondent olefin (21 %), which was submitted to a photosensitized oxygenation reaction, using Faulkner s protocol. A mixture of diasteroisomeric 16-hydroxycleroda-4(18)-13-dien-16,15-oIide and 15-hydroxycleroda-4(18)-13-dien-15,16-olide (2:1) was obtained in 15% yield and was separated by silica gel column chromatography. Reduction of 16-hydroxycleroda-4(18)-13-dien-16,15-oIide with NaBH4, followed by treatment with PCC, furnished the expected lactone cleroda-4(18),13-dien-16,15 olide in 7% yield. Most of the syntetized compounds were submitted to a letality test with Artemia salina Leach.

ASSUNTO(S)

sintese organica

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