Development of Novel Stereoselective Pinacol Coupling Reactions

发展了下列立体选择性的片呐醇类型的反应。(1)在二甲基甲酰胺中，用CrCl2和Me_3SiCl完成了α，β与不饱和酮和醛的交叉频那醇型偶联反应。证明了反应的非对映选择性与反应温度有关。(2)氧取代二烯和醛的交叉偶联反应生成1，2-二醇衍生物是在催化剂B_(12)和水的存在下与CrCl2发生的。(3)利用CrCl2、Mn2和Me_3SiCl3实现了脂肪醛的dl选择性片呐醇偶联反应，并收集了有关片呐醇与低价金属偶联反应的信息。(1)分离得到了一种对芳香醛的dl选择性片呐醇偶联反应有效的钛(III)配合物TiCl3(Tmeda)(THF)，并用X-射线单晶分析对其分子结构进行了表征。(2)分离了具有TP配体的钛(III)和钒(III)配合物，并通过X-射线晶体分析确定了一个醛配位的钒(III)配合物的结构。

The following stereoselective pinacol-type reactions are developed. (1) A cross-pinacol-type coupling reaction of α,β-unsaturated ketones and aldehydes is accomplished with CrCl_2 and Me_3SiCl in DMF. The diastereoselectivity of the reaction is proved to depend on the reaction temperature. (2) A cross-coupling reaction of oxygen-substituted dienes and aldehydes leading to 1,2-diol derivatives is performed with CrCl_2 in the presence of a catalytic amount of B_<12> and water. (3) A dl-selective pinacol-coupling reaction of aliphatic aldehydes is achieved with CrCl_2, manganese, and Me_3SiCl.In addition, we collected information on the pinacol coupling reactions with low-valent metals. (1) A titanium(III) complex TiCl_3(tmeda)(thf) which is effective for a dl-selective pinacol-coupling of aromatic aldehydes, is isolated, and the molecular structure of the complex are examined by X-ray crystallographic analysis. (2) Titanium(III) and vanadium(III) complexes having a Tp ligand are isolated, and the structure of an aldehyde-coordinated vanadium(III) complex is determined by X-ray crystallographic analysis.