利用 Vilsmeier-Haack 反應合成海洋生物鹼 isophakellin 及 ugibohlin 的 A-B-C 三環結構

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2011

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天然界中有一系列的海洋生物鹼,包含isophakellin (1a) 、 ugibohlin (5b) 和其他結構類似物,它們具有pyrrole和imidazole的單元結構,並被證實含有抗腫瘤、抑制免疫的活性與顯著的低毒性,讓這些海洋生物鹼成為全合成的目標產物。我們主要的研究目標,為發展三環化合物4-amino-5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one (3-10a~3-10d) 的合成途徑,做為isophakellin (1a) 和 ugibohlin (5b)的A-B-C三環並作為其全合成的前驅物。 在海洋生物鹼A-B-C三環的合成研究中,我們利用pyrrole (3-1) 與trichloroacetyl chloride 行Friedel-Crafts reaction生成2-(trichloroacetyl)-1H-pyrrole (3-3),再將其水解為pyrrole-2- carboxylic acid (3-6) 與一系列N-alkyl proline amides進行脫水反應合成含有A-C環的N-(1H-Pyrrole-2-carbonyl)-pyrrolidine-2-carboxylic acid amides (3-9a~3-9f) ,這些醯胺化合物經由Vilsmeier-Haack反應得到預期的A-B-C環化合物研究,我們的研究成果提供實用途徑來合成三環化合物(3-10a~3-10d),並可作為 isophakellin (1a) 和 ugibohlin (5b) 全合成的前驅物。
A series of marine natural products, including isophakellin (1a) and ugibohlin (5b), have been reported to conceive pyrrole and imidazole units. They have been revealed to contain effective antitumor activity, essential immunosuppressive activity and obvious low toxicity, which have enabled these alkaloids to become attractive targets for total syhthesis. Our specific aim was to establish a feasible synthesis for the tricyclic A-B-C ring of marine alkaloids, 4-amino-5,6,7,9- tetrahydropyrrolo[2,3-f]indolizin-9-one (3-10a-3-10d), as synthetic precursors for the total synthesis of isophakellin (1a) and ugibohlin (5b). In our synthesis of the tricyclic A-B-C ring of marine alkaloids, 2-(trichloroacetyl)-1H-pyrrole (3-3) as starting material was prepared from pyrrole (3-1) and trichloroacetyl chloride by Friedel-Crafts reaction. 2-(Trichloroacetyl)-1H-pyrrole (3-3) was hydrolyzed to pyrrole-2- carboxylic acid (3-6) and then coupled with a series of N- alkyl proline amides to afford N-(1H-pyrrole-2-carbonyl)-pyrrolidine-2-carboxylic acid amides (3-9a~3-9f), as the A-C ring units. These amides were subjected to the optimized Vilsmeier-Haack reaction condition and the desired tricyclic A-B-C ring of marine alkaloids such as isophakellin (1a) and ugibohlin (5b) were obtained in good yields The expedient synthesis of tricyclic ring compound (3-10a~3-10d) provide suitable precursors for the total synthesis of isophakellin (1a) and ugibohlin (5b).

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海洋生物鹼, marine alkaloid

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