Et<sub>2</sub>AlCl-Promoted Asymmetric Phenylseleno Group Transfer Radical Cyclization Reactions of Unsaturated β-Hydroxy Esters
作者:Dan Yang、Qiang Gao、Bao-Fu Zheng、Nian-Yong Zhu
DOI:10.1021/jo048322z
日期:2004.12.1
unsaturated α-phenylseleno β-hydroxy esters underwent radical cyclization in the presence of Et2AlCl in benzene with sunlamp irradiation at 25−30 °C to give mono- and bicyclic group-transferred products in an efficient and highly regioselective and diastereoselective manner. To rationalize the high diastereoselectivities observed in this reaction, we propose a model based on chelation control of the
我们已经开发出一种不饱和β-羟基酯的不对称苯基硒基转移自由基环化的新方法。在Et 2存在下对各种不饱和α-苯基硒基β-羟基酯进行自由基环化在25-30°C的日光照射下,苯中的AlCl以有效,高度区域选择性和非对映选择性的方式生成单环和双环基团转移的产物。为了合理化此反应中观察到的高非对映选择性,我们提出了基于螯合控制就地形成的铝醇盐的模型。我们设计了一种制备手性自由基前体的通用方法,从中我们获得了高度光学纯的单环和双环基团转移产物。我们正式的(-)-wilforonide的全合成证明了该方法的合成优势。本文介绍了通过1,2-不对称诱导发生的立体选择性基团转移自由基环化的第一个例子。