Synthesis of the 5-7-6 Core of Guanacastepenes. Construction of C8 Quaternary Carbon via the Inversion of Stereochemistry
作者:Truc M. Nguyen、Robert J. Seifert、Dale R. Mowrey、Daesung Lee
DOI:10.1021/ol026820t
日期:2002.10.1
[GRAPHICS]An efficient and unique route to the 5-7-6 core of guanacatepene A (1) is described. The installation of the desired stereochemistry at the C8 position was achieved via the desymmetrization of the cyclohexadienone by reductive ring closure of the seven-membered ring. That the closure of the seven-membered ring produced only the desired isomer is hypothesized to be a result of the more stable trans relationship between the C8 and C11 methyl groups.
Progress towards the total synthesis of guanacastepene A. Approaches to the construction of quaternary carbons and the 5-7-6 tricyclic carbon skeleton
作者:Truc M. Nguyen、Daesung Lee
DOI:10.1016/s0040-4039(02)00729-3
日期:2002.5
The construction of the 5-7-6 tricyclic skeleton of guanacastepene A, including the quaternary carbons, has been achieved. The C-11 and C-8 quaternary carbons were constructed by cuprate addition and carbene insertion, respectively. The 5-7-6 tricyclic core was generated by a selective aldol and SmI2-induced intramolecular aldehyde–alkene coupling.