105(P53) 本邦産軟体サンゴ(Briareum sp.)の新ブリアランブテノライド(ポスター発表の部)

概要

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In the course of our continuous search for soft coral metabolites, we have isolated four new butenolidic briaran diterpenes (4-7) from a Briareum species collected in the sea near Satsuma Peninsula. Their broad structural features and relative positions of substituents were deduced from high-field 2D-n.m.r experiments (1H, 1H- and 1H, 13C-COSY, HMBC, and COLOC). The relative configurations for the briaranes were mainly based on NOE data (N.O.e. difference spectroscopy and NOESY experiments). However, because of the flexibility of the ten-membered ring of the briaran the stereochemistries at C3 and C4 remained uncertain. Thus, conformational analysis by molecular mechanics (MM) calculations using MacroModel package were carried out to confirm the stereochemistries at C3 and C4 and also to determine the most stable conformations of the compounds in solution. The coupling constants for the MM-calculated conformers agreed well with the experimentally observed values.
天然有機化合物討論会の論文
1997-07-20