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|Title:||利用親電子性芳香環取代反應合成海洋生物鹼isophakellin 的 A-B-C 三環結構|
|Abstract:||有一系列海洋天然物的結構已被證實含有pyrrole和imidazole單元，例如phakellin 和isophakellin。海洋生物鹼phakellin 和isophakellin的結構是由四環組成且互為結構異構物。兩者的區別在於A環和C環之間的鍵結不同，isophakellin的A-C環是由C-C鍵組成，而phakellin則為N-C鍵結。合成phakellin和isophakellin的關鍵決定於在A環和C環之間的N-C或C-C鍵的生成。
我們的研究目標為藉由親電子性芳香環取代反應合成出isophakellin的A-B-C 三環。於本論文第二章中，由pyrrole-proline化合物合成三環3-bromo-1-methyl-(5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one)結構，並且探討三環的環上碳原子的電子親核性。於第三章中，由pyrrole-proline-ester 或 pyrrole-proline等中間產物在不同的路易士酸條件下進行Friedel-Crafts 反應探討A-B-C三環的合成。
於第四章，由N-(1-methyl-pyrrole-2-carbonyl)-pyrrolidine-2-carboxylic acid dialkyl amides在三氯氧磷的條件下進行Vilsmeier–Haack反應，得到三環結構dialkylamino-5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one的衍生物。若由alkyl amides進行Vilsmeier–Haack反應則會得到氧化產物4a-hydroxy-1-methyl- (4,4a,5,6,7,9-hexahydropyrolo[2,3,f]indolizine-4,9-dione (4.42)。第五章則研究探討由化合物 4.42架構isophakellin的cyclic guanidine方法。
本論文成功的由親電子性芳香環取代反應合成 C-C鍵結的A-B-C三環5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one 衍生物，所得的三環化合物可以作為天然物 N-methyldibromoisophakellin全合成的前驅物。|
A series of marine natural products have been identified to contain pyrrole and imidazole units such as phakellin and isophakellin. The structures of phakellin and isophakellin both consist of tetracyclic ring systems which are a pair of structural isomers and differ only in the connectivity between ring A and C. Isophakellin have a C-C connectivity between ring A and C while phakellin have a C-N connectivity. The synthesis of phakellin and isophakellin is determined by the selectivity of C-N/C-C bond formation between the pyrrole (ring A) and the imidazole (ring D). Our research goal is to apply the electrophilic aromatic cyclization to construct the A-B-C ring of isophakellin. In Chapter II, tricyclic ring, 3-bromo-1-methyl- (5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one), was synthesized from pyrrole- prolinol adduct and the nucleophilicity of the ring-carbons of tricyclic heterocycle has been established. In Chapter III, the cyclization of tricyclic A-B-C ring by Friedel-Crafts reactions from the intermediates pyrrole-proline-ester or pyrrole- proline with various Lewis acids were discussed. In Chapter IV, treatment of N-(1-methyl-pyrrole-2-carbonyl)-pyrrolidine-2- carboxylic acid dialkyl amides with phosphours oxychloride to undergo Vilsmeier- Haack reaction afforded the tricyclic dialkylamino-5,6,7,9-tetrahydropyrrolo-[2,3-f]- indolizin-9-one derivatives. However, alkyl amides gave exclusively the oxidized product, 4a-hydroxy-1-methyl-(4,4a,5,6,7,9-hexahydropyrolo[2,3,f] indolizine-4,9- dione (4.42), by Vilsmeier–Haack reaction. In Chapter V, the construction of the cyclicguanidine of isophakellin from compound 4.42 was investigated. The A-B-C rings, 5,6,7,9-tetrahydropyrrolo[2,3-f]indolizin-9-one derivatives, were successful synthesized via electrophilic aromatic reactions which could be used as synthetic precursors for the total synthesis of N-methyldibromoisophakellin.
|Appears in Collections:||學位論文|
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