Chemical Studies on Rubiaceous New Type Modified Indole Alkaloids

泰国茜草科植物钩藤中的新型修饰吲哚生物碱-从该植物中分离到四个新的结构类型未知的新吲哚生物碱。阐明了它们的结构，并进行了合成研究。因此，第一个生物碱，沙拉酸(US-6)被认为是D-Seco修饰的氧化吲哚生物碱，被认为是通过20，21烯胺型双键的氧化裂解而形成的。从羟色胺与相应的丙醛缩合反应出发，进行了-沙拉酸的全合成。第二和第三生物碱US-7和US-8与沙拉酸属于同一结构类。人们试图从已知的天然生物碱或全合成中进行化学衍生。第四个生物碱US-9为新的C-环氧吲哚生物碱，其结构为3-氧代-7-羟基-3，7-环叶茶碱。钩藤碱或异钩藤碱的化学衍生学证明了其相对和绝对的立体化学结构。在虎杖中发现了一种新的修饰吲哚生物碱-新的吲哚生物碱--蒲公英苷和脱氧半乳糖苷。通过C-3，3-表马豆苷及其异构体的合成证明了其立体结构。这些化合物在自然界中一直被认为是继已知的中间体--斯特里托西丁和斯特里托塞胺之后的生物合成事件中的关键成员。进一步对其化学成分进行了详细研究，得到了一种酸性葡萄糖生物碱，其结构为严格糖苷酸。

New type modified indole alkaloids in Thai Rubiaceous plant, Uncaria salaccensis --- From the titled plant four new seco indole alkaloids of hitherto unknown structure classes were isolated. Their structures were elucidated and synthetic studies were made. Thus the first alkaloid, salacin (US-6) was found to be a D- seco modified oxindole alkaloid which was regarded to be formed through oxidative cleavage of 20,21 enamine type double bond. Total synthesis of -salacin was carried out starting from condensation of oxytryptamine and the corresponding car aldehyde. Second and third alkaloids, US-7 and US-8, belonged to the same structural class as salacin. Attempts of chemical derivation from known natural alkaloids or total synthesis were made. Fourth alkaloid, US-9, was new type C-seco oxindole alkaloid and the structure was found to be 3-oxo-7-hydroxy-3,7-secorhyn- chophylline. Chemical derivation from rhynchophylline or isorhynchophylline proved the relative and absolute stereochemistry.Modified endole alkaloids of Ophiorrhyza pumila of Rubiaceae --- New type modified indole alkaloids, pumiloside and deoxypumiloside, were found in Ophiorrhiza pumila. The stereo structure was proved through synthesis of pumiloside and its isomer at C-3, 3-epipumiloside. These compounds were long postulated and sought for in the nature as the key members in the "Poststrictosamide Biosynthetic Events" that follow the known intermediates, strictosidine and strictosamide. Further detailed study on the constituents of O. pumila gave an acidic gluco alkaloid and the structure was found to be strictosidic acid.