Estudo fitoquimico de Baccharis myriocephala e uso de beta-pineno para a obtenção de orto-mentanos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

This thesis was developed into two different parts. Part A involves the phytochemical investigation of roots and aerial parts of Baccharis myriocephala. The specimen was collected in Serra do Mar, São Paulo. From the hexane and methanolic extract we have detected and isolated poliacetylenes, (-)-caryophyllene oxide, baccharis oxide, b-friedelanol and long chain hydrocarbons. Polyacetylene possessing ene-diine-diene chromophore was detected, but its instability prevented isolation or further studies. Baccharis oxide is a common Baccharis triterpene never fully characterized by spectroscopy. A full assignement of its proton and carbon signals using 2D NMR spectroscopy and C,C correlations (2D INADEQUATE) was accomplished. It was further observed that the ring C assumes a boat conformation in solution. ln the second part of this work we focused our attention in the synthesis of ortho-menthanes, a class of monoterpene not very diffused in nature and with a small amount of synthesis reported. Our strategy was the use of a b-pinene rearranged skeleton, lactone 15, to access the ortho-menthanes in few steps. Optimization of the lactone 15 production involved a selection of oxidant and reaction conditions. The best conditions furnished the desired rearranged compound 15, in 46%. Large scale reaction led to the lactone 15 in the desired amount and during its purification we have isolated ether 14, a novel rearranged product. Lactone 15 was treated with perchloric acid producing two novel dimers 29 e 31. Treatment of 15, with SnCl4 led to the isolation of 32 with an orho-menthane skeleton. An ortho-menthane derivative was also obtained when submitting ether 14 to the same Lewis acid.

ASSUNTO(S)

quimica vegetal quimica organica - sintese

ACESSO AO ARTIGO

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