Coupling of Cyclobutenediones with Fischer Carbene Complexes: A One-Step Synthesis of Cyclopentenediones and/or 5-Alkylidenefuranones via Net Insertion of the Carbene Unit into a C−C Bond<sup>1</sup>
作者:Metin Zora、Yuhui Li、James W. Herndon
DOI:10.1021/om9905198
日期:1999.10.1
The reaction of Fischer carbene−chromium complexes with 3-cyclobutene-1,2-diones has been investigated. In most cases, the major product of the reaction is the C−C bond insertion product, a 2-alkoxy-4-cyclopentene-1,3-dione, accompanied by a minor amount of the partial deoxygenation product, a 4-cyclopentene-1,3-dione. In some cases, 5-alkylidenefuranones are also formed. A mechanism involving oxidative
费歇尔卡宾-铬配合物与3-环丁烯-1,2-二酮的反应已得到研究。在大多数情况下,反应的主要产物是CC键插入产物2-烷氧基-4-环戊烯-1,3-二酮,并伴随有少量的部分脱氧产物4-环戊烯- 1,3-二酮 在某些情况下,还会形成5-亚烷基呋喃酮。为了解决环戊二烯的形成,提出了一种机制,该机制涉及氧化性加成不饱和菲舍尔卡宾配合物,然后进行酰基迁移和还原消除。认为呋喃酮的形成是通过酰基迁移产物的脱金属,然后是O-酰化而产生的。记录了环戊二烯/亚烷基-呋喃酮比率的电子依赖性,该比率使用哈米特方程进行了评估。