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.
作者:TAKEHIRO SANO、JUN TODA、NORIAKI KASHIWABA、TAKESHI OHSHIMA、YOSHISUKE TSUDA
DOI:10.1248/cpb.35.479
日期:——
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).
基于激活的丁二烯与二氧吡咯啉进行Diels-Alder反应的策略,实现了erythrinan类生物碱的全合成。异喹啉吡咯二酮(15)与1,3-双氧取代的丁二烯反应,以区域特异性和立体选择性的方式生成erythrinan衍生物(20)和(21)。通过锂硼氢化物还原加合物(20)或(21),随后进行酸水解得到烯酮(33)。对33进行甲磺酰化,随后在中性条件下进行脱甲氧羰基化得到二烯酮(43)。对43进行Meerwein-Ponndorf还原,随后进行甲基化得到erysotramidine(2a)和8-氧代erythraline(2b)。对8-氧代衍生物(2)进行铝氢化还原得到dl-erysotrine(1a)和dl-erythraline(1b)。