作者:Scott E. Denmark、Karl L. Habermas、Gary A. Hite、Todd K. Jones
DOI:10.1016/s0040-4020(01)90571-x
日期:1986.1
The silicon-directedNazarovcyclization was shown to proceed with good to excellent stereoselectivity in cyclohexenyl systems bearing a variety of ring substituents. In all cases the trans family of isomers predominated, and cis ring-fused products were formed exclusively. The potential for stereocontrol by increasing the bulk of silicon substituents was limited for five-membered rings and good for
Synthetic Studies Towards Novel Terpenic Natural Products Kelsoene and Poduran: Construction of the Complete 4-5-5-Fused Tricarbocyclic Core
作者:Goverdhan Mehta、K. Srinivas
DOI:10.1055/s-1999-2670
日期:1999.5
A common synthetic approach to the recently reported sesquiterpene kelsoene 1 and the tetraterpene poduran 5, bearing a novel tricyclo[6.2.0.02,6]decane framework, from commercially available 1,5-COD and leading to the first construction of the carbocyclic core present in these natural products is delineated.
(±)-Kelsoene (1) has been synthesized in 15 steps from commercially available cyclopent-2-en-1-one. Key steps include (a) a methylenecyclopentane annulation of cyclopent-2-en-1-one using the bifunctional cuprate reagent lithium cyano(4-chlorobut-1-en-2-yl)cuprate and (b) a highly stereoselective [2+2]-photocycloaddition of ethylene to the bicyclic enone 10.