Synthesis of a tetraoxy-bis-nortaxadiene, en route to taxol, using a cascade radical cyclisation sequence
作者:William P.D. Goldring、Gerald Pattenden、Stuart L. Rimmington
DOI:10.1016/j.tet.2009.04.021
日期:2009.8
taxadiene could be observed. In contrast, the iododienynedione 41, i.e., deoxy 36, underwent a tandem radical macrocyclisation–transannulation sequence, when treated with Bu3SnH–AIBN, leading to the tetraoxy-bis-nortaxadiene 42 in 44% yield. Attempts to synthesise the alcohol 28b from the silyl ether 28a en route to the iodide 28c instead gave the substituted tetrahydrofuran 29 via an intramolecular oxy-Michael
描述了从对应于紫杉烷中的环A的环己醛18和乙烯基锡烷24开始的取代烯键28a,33b和36的简明合成。用Bu 3 SnH–AIBN处理36不会导致串联自由基大环化-自由基转环序列预期的氧取代紫杉二烯37的产生;相反,结果混合了不明的产品。当在类似条件下用Bu 3 SnH–AIBN处理对应于醇36的PMB醚33b时,p-茴香醛作为主要副产物被分离出来,但是没有观察到形成紫杉二烯的证据。相比之下,当用Bu 3 SnH-AIBN处理时,碘二烯二酮41(即脱氧36)经历了串联自由基大环化-环转移序列,从而以44%的产率产生了四氧-双-北-紫杉二烯42。尝试从甲硅烷基醚28a到碘化物28c的路线合成醇28b,而是通过分子内的氧-迈克尔反应得到了取代的四氢呋喃29。