Viabilização da sintese quiral de stipodiol

AUTOR(ES)
DATA DE PUBLICAÇÃO

1983

RESUMO

Motivated by always increasing number of publications on marine natural products and the isolation oí diterpenes from the brown alga Stipopodium zonale we have undertaken the synthesis of stypodiol. While not toxic, stypodiol, induces an intense hyperactivity and is perhaps in part responsible for the "escape " behavior observed when fishes encounter the algae in an enclosed aquarium. The main target of this worth was the assymetric total synthesis of stypodiol and to determine its absolute configuration. The key to the synthesis designing was the disconnection of the target molecule in two synthons one possessing a diterpene and the other an aromatic skeleton. As the diterpene synthon holds alI the quiral carbons of the target molecule, the choice of an adequate chiral template was of uppermast importance to the synthesis success. In this connection the 3-hydroxy and 3-acetoxy copalic acids,easily obtainable from the commercial copaiba oil,were chosen as our chira! templates. ln our synthetic work, however,we have used copalic acid, a more abundant resinic acid from the copaíba oil possessing analogous structure but lacking the 3-hydroxy or 3-acetoxy substituente, eaving our chiral templates to be used when the optimum conditions were determined. Taking into consideration that one of the major difficulties lies in the C-C bond formation between the aromatic and the diterpene synthons we have tried three different paths using 12-dithio-13-isocopa!en-15-ol, ent-labd-8(17),13-dien-15-ol and 14-isocopalanone as chiral templates. To obtain the aromatic synthons, toluquinol,(2-benzyloxy 3-methyl-5-methoxy) benzylmagnesium bromide and(2-benzyloxy-3-methyl 5-methoxy) benzyltriphe nylphosphonium bromide, we have chosen hydroquinone as our starting material. After testing three different alternative routes we have come to the conclusion that the one using ent-ladb-8(17) ,13dien-15-ol as the diterpenic synthon seems the more adequate. While developing out synthetic work we have also devoted part of our attention to the discussion of the spectroscopic data of alI synthetic intermediates.

ASSUNTO(S)

sintese organica compostos organicos

ACESSO AO ARTIGO

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