Macrocyclization studies and total synthesis of cyclomarin C, an anti-inflammatory marine cyclopeptide
摘要:
The studies on macrocyclization at possible sites toward the total synthesis of cyclomarin C are described. The results showed that both Trp and Phe derivatives involved in the target could not be the terminals of the final linear peptide precursors. Additionally, preparation of corresponding dipeptides with an N-methyl amide bond is not favorable in the synthesis of linear precursors. Site d was finally proved a proper site for the cyclopeptide formation, and the corresponding head-to-tail macrocyclization was achieved under mild conditions and gave repeatable and satisfactory yields. (c) 2005 Elsevier Ltd. All rights reserved.
Isolation, Structure Elucidation and Total Synthesis of Lajollamide A from the Marine Fungus Asteromyces cruciatus
摘要:
从美国圣地亚哥拉荷亚海岸获得的海洋来源丝状真菌Asteromyces cruciatus 763,产出了新的五肽lajollamide A (1),以及已知化合物regiolone (2)、hyalodendrin (3)、gliovictin (4)、1N-norgliovicitin (5)和bis-N-norgliovictin (6)。lajollamide A (1)的平面结构通过核磁共振(NMR)光谱和质谱结合确定。lajollamide A (1)的绝对构型通过全合成得到明确解决,合成过程中获得了三个额外的非对映异构体,并揭示了在化学降解过程中l-亮氨酸和l-N-甲基亮氨酸残基发生了意外的酸介导部分消旋化(2:1)。对分离的代谢物的生物活性,特别是抗菌性质进行了系列检测。