Search for New Synthetic Reactions using Acylzirconocene Complex as an "Unmasked" Acyl Anion

在我们正在进行的研究项目中，我们利用了酰基二茂锆络合物进行新的合成反应，为有机合成开发了巨大的可能性。在过去的项目期间，我们建立了几个相当新的合成反应，在这些反应中，酰基二茂锆氯化物与醛在化学计量比的Lewis酸存在下反应得到a-酮醇衍生物。这是第一个例子，酰基二茂锆氯反应为“未遮盖”的酰基阴离子。我们还发现了钯催化的酰基二茂锆氯化物与有机卤化物的反应，得到了酮的衍生物。此外，在Pd催化条件下，酰基二茂锆络合物与α，β-不饱和酮发生区域选择性加成反应。在1，2-选择性加成条件下，首次利用手性膦配体实现了“无掩蔽”的酰基阴离子的不对称加成反应。虽然目前反应中的不对称诱导率(66%ee)还不是很高，但我们目前正在继续研究，以寻找更有效的锆金属络合物的手性配体。

In our ongoing research project on new synthetic reactions using acylzirconocene complex, we have exploited enormous possibilities of acylzirconocene complex for organic synthesis. During the past term of the project we established several quite new synthetic reactions in which acylzirconocene chloride reacted with aldehyde in the presence of a stoichiometric amount of Lewis acid to give a-ketol derivatives. It is the first example that the acylzirconocene chloride reacts as an "unmasked" acyl anion. We also found a Pd-catalyzed reaction of acylzirconocene chloride with organic halides to give ketone derivatives. Moreover, in the Pd-catalyzed conditions, acylzirconocene complex adds to α, β-unsaturated ketones, regioselectively. In the 1, 2-selective addition conditions, an enantioselective addition of the "unmasked" acyl anion was achieved for the first time by the use of chiral phosphine ligand. Although the asymmetric induction (66% ee) in the present reaction is not satisfactorily high yet, we are currently continuing the research to find more effective chiral ligand for zirconium metal complex.