Sintese formal enantiosseletiva do (-)-disidiolidio e outros estudos sinteticos envolvendo vinilcicloexenos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

With the present research work we envisaged both the preparation and the application of vinylcyclohexene-type dienes as pivotal intermediates in synthetic pathways aiming the preparation of natural products (terpenoids) possessing bicyclic, partially-rearranged skeletons. Convergent construction of the decalin framework was turned to the Diels-Alder reaction of a seemly vinylcyclohexene and a suitable dienophile. Our synthetic strategy entailed organotin compounds (vinylstannanes), enoltri- flates and palladium-catalysed reactions (Stille coupling reaction) application and thus synthesis of potencially useful vinylcyclohexenes to reach the dysidiolide (32) (g-hidroxybutenolide from Dysidea etheria de Laubenfels), the salmantic acid (25) and the salmantidiol (26) (diterpenes from Cistus laurifolius) and the tetra-nor-halimanoic acid (29) (from Vellozia flavicans) was accomplished. The Thesis was partitioned into two ultimate sections. The first one glances over racemic dysidiolide preparation followed by the enantioselective trials involving 1) successful biocatalysis over pro-chiral cyclohexane-1,3-diones with microorganisms isolated in the national territory as a resort to obtain quirons for an asymmetric synthesis and 2) deracemizing alkylation reaction of ()-2-methylcyclohexanone by using chiral imines (d Angelo s procedure), affording ultimately a chiral vinylcyclo-hexene which delivered us the formal synthesis of the title compound. The ensuing, late section deals with synthetic studies involving the preparation and the application of vinylcyclohexenes in thermal Diels-Alder reactions, furnishing advanced intermediates possessing the core structure of the above-mentioned salmantic acid (salmantidiol) and the tetra-nor-halimanoic acid. For the latter, revision of the previously published structure was proposed.

ASSUNTO(S)

diels-alder produtos sinteticos redução (quimica) reações quimicas reação de

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