Synthesis of Erythrina and related alkaloids. XVI Diels-Alder approach : Total synthesis of dl-erysotrine, dl-erythraline, dl-erysotramidine, dl-8-oxoerythraline and their 3-epimers.
SANO TAKEHIRO; TODA JUN; KASHIWABA NORIAKI; TSUDA YOSHISUKE; IITAKA YOICH+, HETEROCYCLES, 1981, 16, NO 7, 1151-1156
作者:SANO TAKEHIRO、 TODA JUN、 KASHIWABA NORIAKI、 TSUDA YOSHISUKE、 IITAKA YOICH+
DOI:——
日期:——
Synthesis of Erythrina and related alkaloids. XVI Diels-Alder approach : Total synthesis of dl-erysotrine, dl-erythraline, dl-erysotramidine, dl-8-oxoerythraline and their 3-epimers.
Total synthesis of erythrinan alkaloids was achieved by a strategy based on the Diels-Alder reaction of activated butadienes to a dioxopyrroline. The reaction of isoquinolinopyrrolinedione (15) with 1, 3-bis-O-substituted butadienes proceeded in a regiospecific and stereoselective manner to give erythrinan derivatives (20) and (21). Lithium borohydride reduction of the adduct (20) or (21), followed by acid hydrolysis afforded the enone (33). Mesylation of 33 and subsequent demethoxycarbonylation of 42 under neutral conditions gave the dienone (43). Meerwein-Ponndorf reduction of 43 and subsequent methylation afforded erysotramidine (2a) and 8-oxoerythraline (2b). Aluminum hydride reduction of the 8-oxo derivatives (2) furnished dl-erysotrine (1a) and dl-erythraline (1b).
an oxidation/reduction approach. The N-oxide derivatives of the jamtine isomers were also synthesized and identified by X-ray crystallographic analysis. Additionally, a density functional theory calculation for the four possible N-oxide structures was exploited to gain further insight into the structure of the natural product in comparison to those of the synthetic N-oxides, because the NMR data of
报道了四氢异喹啉生物碱果酱及其差向异构体的新合成。合成策略取决于一锅共轭还原/罗宾逊环化序列和通过氧化/还原方法进行的有效苄基构型反转。Jamtine 异构体的 N-氧化物衍生物也被合成并通过 X 射线晶体学分析进行鉴定。此外,利用四种可能的 N-氧化物结构的密度泛函理论计算,与合成 N-氧化物的结构相比,进一步深入了解天然产物的结构,因为合成衍生物的 NMR 数据不匹配那些报告的天然果酱 N-氧化物。