6-Exo-spiro (Alkoxycarbonylamino)methyl Radical Cyclization: Highly Regio- and Stereoselective Synthesis of (−)-Sibirine
作者:Masato Koreeda、Yamin Wang、Liming Zhang
DOI:10.1021/ol026671e
日期:2002.9.1
[reaction: see text] The (methoxycarbonylamino)methylradical can be readily generated from its PhSe precursor and undergoes preferential 6-exo-spiro cyclization when PhSO(2) is attached at the distal alkene carbon. This property was applied to the synthesis of the racemic and optically active spirocyclic alkaloid sibirine.
Spirocyclic alkaloids, (±)-isonitramine and (±)-sibirine were synthesized in high overall yields via a chemoselectivereduction by Hantzsch ester (HEH), a coenzyme NADHmodel compound.
[reaction: see text] Substitution at nitrogen by alpha,beta-unsaturated acylradicals took place accompanied by elimination of an alpha-phenethyl radical. This reaction led to the development of a new carbonylative annulation method for five- to seven-membered ring lactams.
The intramolecular nitrile oxide cycloaddition route to spirocyclic alkaloids. A total synthesis of isonitramine and sibirine
作者:Alan P. Kozikowski、P.-W. Yuen
DOI:10.1039/c39850000847
日期:——
The Intramolecularnitrileoxidecycloaddition reaction has been found to accommodate the construction of spirocycles in modest yield as revealed by a synthesis of the title alkaloids.
如标题生物碱的合成所揭示的,已经发现分子内一氧化氮环加成反应以适中的产率适应螺环的构建。
McCloskey, Patrick J.; Schultz, Arthur G., Heterocycles, 1987, vol. 25, p. 437 - 447