From osmium hydrido vinylidene to osmacycles: the key role of osmabutadiene intermediates.
From osmium hydrido vinylidene to osmacycles: the key role of osmabutadiene intermediates.
复制标题
DOI：
10.1002/asia.201200872
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Qianyi Zhao;Xiao-Yu Cao;T. Wen;H. Xia
中科院分区：
文献类型：
--
作者：
Qianyi Zhao;Xiao-Yu Cao;T. Wen;H. Xia
锇配位亚乙烯基1与活化的末端炔具有不同的环化反应活性。1与HC-CCOR'（R'= OEt和Me）反应，通过锇烯基/亚乙烯基2a和2b得到锇呋喃3a和3b。此外，1与HC_（12）CCH（OH）C_（12）CH反应生成奥斯马苯4，其中炔醇作为C（5）片段与1环化。机理分析表明，这些反应以及1与HC_（10）CCH（OH）R（R=Ph、Et和乙烯基）或HC_（10）CCH（OEt）（2）之间的[3+3]环加成反应都经过类似的奥斯马布韦中间体。随后，中间体要么采取“配位和环化”过程或“碳-碳偶联”路径环化，这取决于末端烯基碳原子上的取代基的配位能力。
Osmium hydrido vinylidene 1 shows diverse cyclization reactivity with activated terminal alkynes. Treatment of 1 with HC≡CCOR' (R'=OEt and Me) gave osmafurans 3a and 3b via osmium alkenyl/vinylidenes 2a and 2b. In addition, 1 reacted with HC≡CCH(OH)C≡CH to yield osmabenzene 4, in which the alkynol acted as a C(5) fragment to cyclize with 1. Mechanistic analysis indicates that these reactions and the previous formal [3+3] cycloadditions between 1 and HC≡CCH(OH)R (R=Ph, Et, and vinyl) or HC≡CCH(OEt)(2) all go through similar osmabutadiene intermediates. Subsequently, the intermediates either took a "coordination and cyclization" process or a "carbon-carbon coupling" path to cyclization, depending on the coordination ability of substituents on the terminal alkenyl carbon atom.