Development of Novel Oxidative Transformation Based on Heterometallic Electron Transfer

主族有机金属的单电子氧化与过渡金属的单电子氧化反应允许一种基于金属表面电子态变化的新的反应行为，这被认为提供了新的合成反应。如果发生金属过渡反应，基于引入金属的特性的反应性有望通过有机金属中间体拓宽合成方法的范围。在本研究项目中，具有单电子氧化能力的氧钒化合物被用于此目的。研究了有机金属化合物的氧化转化，为选择性碳-碳键的形成提供了多种方法。1)氧钒(V)化合物，如VO(OEt)Cl2，作为有机锌化合物的氧化剂，提供了相应的交叉偶联产物。特别是三有机锌盐在钒(V)的作用下发生选择性交叉偶联反应。2)VO(OEt)Cl2诱导由溴代芳烃和Me_4ZnLi_2制备的芳基三甲基锌盐的氧化配体偶联，得到相应的甲基芳烃。3)氧钒(V)化合物诱导环α，β-烯酮与二烷基锌试剂的亲核α，β-邻位双烷基化反应。由环烯酮和三烷基锌酸锂生成的烷基锌烯醇酸盐被VO(OEt)Cl2氧化，得到2，3-二烷基环烷酮。在不分离中间络合物的情况下，一锅转化是可能的，并被认为是合成的潜在的。主族有机金属和氧钒化合物之间的氧化还原相互作用被证明允许这些转化。这种偶联被认为是有机金属化合物的形式还原消除，这在传统方法中是很难实现的。

One-electron oxidation of main-group organometallics by one-electron redox with transition metals permits a novel reaction behavior based on the change of the electronic state on metals, which is considered to provide novel synthetic reactions. If transmetallation takes place instead, the reactivities based on the characteristics of the introduced metals are expected to widen the scope of synthetic methods via organometallic intermediates. Oxovanadium compounds with one-electron oxidation capability are employed for this purpose in this research project. The oxidative transformations of organometallics have been investigated to provide versatile methods for selective carbon-carbon bond formation.1) Oxovanadium (V) compounds like VO (OEt) Cl_2 serve as useful oxidants for organozinc compounds, providing the corresponding cross-coupling products derived from two ligands of organozinc compounds. In particular, triorganozincates undergo selective cross-coupling smoothly by the action of oxovanadium (V).2) VO (OEt) Cl_2 induces oxidative ligand coupling of aryltrimethylzincates, prepared from bromoarenes and Me_4ZnLi_2, giving the corresponding methylarenes.3) Oxovanadium (V) compounds induce nucleophilic α, β-vicinal dialkylation of cyclic α, β-enones with dialkylzinc reagents. Alkylzinc enolates, generated from cyclic enones and lithium trialkylzincates, are oxidized by VO (OEt) Cl_2, giving 2, 3-dialkylcycloalkanones. The one-pot transformation is possible without isolation of the intermediate complexes and considered to be of synthetically potetial.The redox interaction between main-group organometallics and oxovanadium compounds is demonstrated to permit these transformations. The coupling is recognized to be formal reductive elimination of the organometallics, which has been less accessible by conventional methods.