Total synthesis of grandisine D (5) was achieved by a Brønsted acid mediated Morita−Baylis−Hillman (MBH) ring-closure reaction and stereoselective aldol condensation with (S)-5-methylcyclohexenone (9) as key steps. The MBH approach was also applicable for the construction of the aza-fused bicyclicsystems of pyrrolizidine and stemona alkaloids.
A Versatile Enantioselective Synthesis of Azabicyclic Ring Systems: A Concise Total Synthesis of (+)-Grandisine D and Unnatural Analogues
作者:Olugbeminiyi O. Fadeyi、Timothy J. Senter、Kristopher N. Hahn、Craig W. Lindsley
DOI:10.1002/chem.201200629
日期:2012.5.7
new six step approach for the rapid and enantioselective synthesis of indolizidine, pyrrolo[1,2‐a]azepine, and pyrrolo[1,2‐a]azocine azabicyclic systems and their respective lactam congeners, which are found in a host of natural products as well as pharmaceutical preparations. This protocol enables a concise enantioselective total synthesis of (+)‐grandisine D in 16.4 % overall yield from commercial
结束对氮杂辛类的研究:我们开发了一种新的六步法,用于快速和对映选择性合成吲哚里西啶、吡咯并[1,2- a ]氮杂和吡咯并[1,2- a ]氮杂双环系统及其各自的内酰胺同系物,它们存在于许多天然产品和药物制剂中。该方案能够从商业材料中以 16.4% 的总产率对 (+)-大地碱 D 进行简明的对映选择性全合成(参见方案)。