Concise Total Synthesis of (±)-Cephalotaxine via a Transannulation Strategy: Development of a Facile Reductive oxy-Nazarov Cyclization
作者:Wei-Dong Z. Li、Wei-Guo Duo、Cheng-Han Zhuang
DOI:10.1021/ol201390r
日期:2011.7.1
A concise totalsynthesis of (±)-cephalotaxine (1) has been achieved from dioxolanone derivative 15 via a transannulation strategy. The key transformation is a facile reductive oxy-Nazarov cyclization as illustrated above, involving presumably a tethered 1,2-oxidopentadienyl cation species 7a or 7b, which represents a new variant of the oxy-Nazarov cyclization and constitutes an effective, regio- and
Flavofungin: a mixture of 13,15,17,19,21,23,25,27-octahydroxy-31-isopropyl-14-methyl- and 13,15,17,19,21,23,25,27-octahydroxy-14-methyl-31-s-butyl-hentriaconta-2,4,6,8,10,28-hexaen-31-olide
作者:R. Bognár、S. Makleit、K. Zsupán、B. O. Brown、W. J. S. Lockley、T. P. Toube、B. C. L. Weedon
DOI:10.1039/p19720001848
日期:——
Flavofungin, the antifungal antibiotic from Streptomyces flavofungini, has been shown to be a mixture (ca. 10:1) of 13,15,17,19,21,23,25,27-octahydroxy-31-isopropyl-14-methyl-(1a) and 13,15,17,19,21,23,25,27-octahydroxy-14-methyl-31-s-butyl-(1b) hentriaconta-2,4,6,8,10,23-hexaen-31-olide. Its relationship to mycoticin is discussed.