Alcaide Benito, Almendros Pedro, Aragoncillo Cristina, Redondo María C
Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain.
J Org Chem. 2007 Mar 2;72(5):1604-8. doi: 10.1021/jo061828s. Epub 2007 Feb 8.
A novel approach to racemic and enantiopure nonconventional fused bi- and tricyclic beta-lactams has been developed by using regio- and stereocontrolled intramolecular free radical reactions in monocyclic 2-azetidinone-tethered allenynes and haloallenes. The access to allene cyclization precursors was achieved by metal-mediated carbonyl allenylation of appropriately substituted 4-oxoazetidine-2-carbaldehydes in an aqueous environment. The tin-promoted radical cyclizations of allene-beta-lactams are totally regioselective for the central allenic carbon, providing bi- and tricyclic beta-lactams containing a seven-membered ring.
通过在单环2-氮杂环丁酮连接的丙二烯和卤代丙二烯中进行区域和立体控制的分子内自由基反应，已开发出一种合成外消旋和对映体纯的非常规稠合双环和三环β-内酰胺的新方法。通过在水性环境中对适当取代的4-氧代氮杂环丁烷-2-甲醛进行金属介导的羰基丙二烯化反应，可获得丙二烯环化前体。丙二烯-β-内酰胺的锡促进自由基环化反应对中心丙二烯碳具有完全的区域选择性，可提供含有七元环的双环和三环β-内酰胺。
