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)。
The Preparation of (−)-Grandisine B from (+)-Grandisine D; A Biomimetic Total Synthesis or Formation of an Isolation Artefact?
作者:James D. Cuthbertson、Andrew A. Godfrey、Richard J. K. Taylor
DOI:10.1021/ol2014939
日期:2011.8.5
has been developed to prepare enantiopure indolizidine building blocks from l-proline and then applied to prepare the Elaeocarpus-derived alkaloids grandisine B and grandisine D in an efficient manner. However, evidence is presented which indicates that grandisine B does not occur naturally but is formed by reaction of grandisine D with ammonia during the extraction/purification process.
first total synthesis of grandisine alkaloids, grandisines B, D, and F, which show affinity for the human δ‐opioid receptor. The key steps in this synthesis are construction of the isoquinuclidinone moiety of 2 by intramolecularimine formation and the tetracyclic ring system of 4 by stereoselective ring closure of the enolate of amine 8 generated by 1,4‐addition of ammonia to 9. Synthesis of key intermediate