Investigations on the Reactivity of Fascaplysin, Part II, General Stability Considerations and Products Formed with Nucleophiles
摘要:
Reversible deprotonation of fascaplysin (1) was achieved with non-nucleophilic bases (Scheme 1). Under basic aqueous conditions, opening of ring D of 1 occurred, yielding zwitter-ionic reticulatine 2a. whereas. in a methoxide-containing MeOH solution, an unexpected addition of three molecules of MeOH to the pyridinium ring produced an isomer mixture 3 of a trimethoxy-substituted compound (Scheme 2). Transformation of the keto group of 1 to the oxime JA took place in the presence of pyridine as base (Scheme 3). Grignard and alkyllithium reagents added as expected to the keto group of 1. providing tertiary alcohols 5 and 6 (Scheme 4).
通过靛蓝与亚甲基活性化合物反应制得吡啶并[1,2- a:3,4- b ']二吲哚系统的一种简单方法是用于合成海洋生物碱6-oxofascaplysin,fascaplysin及其衍生物。还证明了与酮的反应导致靛蓝分解和靛红衍生物的形成。具有在C-7处有一个苯基取代基的fascaplysin衍生物对Fascaplysin的抑制作用是对fascaplysin的2-3倍。
Unexplored reactivity of 2-oxoaldehydes towards Pictet–Spengler conditions: concise approach to β-carboline based marine natural products
作者:Narsaiah Battini、Anil K. Padala、Nagaraju Mupparapu、Ram A. Vishwakarma、Qazi Naveed Ahmed
DOI:10.1039/c4ra01387e
日期:——
Novel reactions under PictetâSpengler conditions between tryptophan methyl ester/tryptamine and 2-oxoaldehydes have been developed and successfully utilized for the total synthesis of Merinacarboline (A and B), Eudistomin Y1, Pityriacitrin B, Pityriacitrin, Fascaplysin and analogues.
Total synthesis of the marine sponge pigment fascaplysin
作者:Benjamin Pelcman、Gordon W Gribble
DOI:10.1016/s0040-4039(00)97367-2
日期:——
Fascaplysin (1), an antimicrobial and cytotoxic red pigmentfrom the marinespongeFascaplysinopsissp., has been synthesized in seven steps from indole (65% yield). The pivotal intermediate in the synthesis is diindole 3 which is induced to undergo acid-catalyzed cyclization and dehydrogenation to afford the desired pentacycle 2 in > 90% yield. Peracid oxidation of 2 yields fascaplysin.
A silver catalyzed and microwave assisted one-pot cascade synthesis provides efficient access to diverse alkaloid-inspired scaffold classes, and a concise and efficient total synthesis of homofascaplysin C and fascaplysin.
Regioselective photo-oxidation of 1-benzyl-4,9-dihydro-3H-β-carbolines
作者:Marcos D. García、A. James Wilson、Daniel P. G. Emmerson、Paul R. Jenkins
DOI:10.1039/b604922b
日期:——
The synthesis of a series of β-carboline-based analogues of the natural product fascaplysin is presented; the compounds were produced using a novel photo-oxidation reaction of 1-benzyl-4,9-dihydro-3H-β-carbolines as the key step.