Leucascandrolide A, a New Type of Macrolide: The first powerfully bioactive metabolite of calcareous sponges (Leucascandra caveolata, a new genus from the coral sea)
作者:Michele D'Ambrosio、Antonio Guerriero、Francesco Pietra、C�cile Debitus
DOI:10.1002/hlca.19960790107
日期:1996.2.7
and with the natural configuration at C(5) (axial). Mosher's MTPA esters 4 and 5 obtained from (+)-2 showed scattered Δδ = (δ(S) − δ(R)) data. However, inversion of the configuration at C(5) led, via ketone (+)-6, to the less encumbered 5-equatorial hydroxy derivative (+)-7, whose MTPA esters 8 and 9 gave consistent Δδ data, allowing the assignment of the absolute configuration of (+)-7, and hence of
Leucascandrolide A((+) - 1),一种新型的双O形桥接18元大环内酯,即,几乎没有Ç 1 -branching与广泛1,3-双加氧和一种特殊的侧链,由一个分离的一种新的钙质海绵,来自珊瑚海的Leucascandra Caveolata BOROJEVIC和KLAUTAU。(+)- 1的酯交换反应产生了衍生自侧链的甲酯3和衍生自大环内酯部分且在C(5)(轴向)具有天然构型的5-羟基衍生物(+)- 2。从(+)-得到的Mosher MTPA酯4和5图2示出了散射的Δδ=(δ(S)-δ(R))数据。但是,C(5)处的构型反转通过酮(+)- 6导致了较少受累的5-赤道羟基衍生物(+)- 7,该化合物的MTPA酯8和9给出了一致的Δδ数据,从而可以进行赋值(+)- 7的绝对构型,因此(+)- 1的绝对构型也是如此。(+)- 1的结构新颖性及其强大的抗真菌和细胞毒性活性可能会重新