Development of Asymmetric Reactions of Diazo Carbonyl Compounds in the Presence of Metal-Catalysts having Axial Chirality

在10mol%稀土金属三氟甲磺酸盐催化下，重氮乙酸苯基酯与醇的反应顺利进行，高产率地得到了α，α-取代产物。苯重氮乙酸薄荷酯的反应具有中等的非对映选择性。本文研究了用刘易斯酸对邻甲氧羰基-α-二氮杂苯乙酮分解生成2-苯并吡喃-4-醇盐的反应进行立体控制，也进行了调查。当Yb（OTf）_3在CH_2Cl_2中存在时，反应具有很高的内选择性。在Et_2O或CH_2Cl_2中，Yb（OTf）_3的加入可使苯甲醛、对位取代苯甲醛和苄氧乙醛的反应具有很高的外消旋选择性。我们还发现，使用10摩尔%的镧系元素三（S）-1，1 ′-联萘-2，2 ′-二基磷酸酯（已知是Danishefsky ′ s二烯的杂Diels-Alder反应的有效催化剂）显示出中等的对映选择性（内：20 - 52%ee），尽管几乎没有观察到非对映选择性。在2，6-二[（4S）-（-）-异丙基-2-恶唑啉-2-基]吡啶和Sc（OTf）_3合成的手性催化剂存在下，对映选择性为86%ee（endo：exo = 76：24）。据我们所知，这是在手性刘易斯酸催化的羰基叶立德环加成反应中发现的第一个不对称诱导的例子。

In the presence of 10 mol % of rare earthmetal triflate as catalyst, the reaction of pheriyldiazoacetate with alcohols proceeded smoothly to give desired α, α-substituted products in high yield. Moderate diastereoselectivity was obtained in the reaction of l-menthyl phenyldiazoacetate. The use of the catalysts, which were prepared by mixing the ligands having axial chirality such as binaphthol and binaphthyldiimine derivatives with rare earth metal triflates, did not show satisfactory results in terms of selectivity and chemical yield.Stereocontrol by using Lewis acid in the reaction of 2-benzopyrylium-4-olate, which was generated by Rh_2( OAc )_4-catalyzed decomposition of o-methoxycarbonyl-α-diazbacetophenone, was also investigated. In the reaction with N-substituted maleimide under reflux in benzene showed exo-selectivity, while the reaction in the presence of 10 mol % of Yb( OTf )_3 in CH_2Cl_2 at room temperature proceed with high endo-slectivity. On the other hand, addition of 10 mol % of Yb( OTf )_3 was quite effective in obtaining high exo-selectiyity in the reaction with benzaldehyde, p-substituted benzaldehyde, and benzyloxyacetoaldehyde in Et_2O or CH_2Cl_2. We also found that the use of 10 mol % of lanthanide tris( S )-1,1'-binaphthyl-2,2'-diyl phosphate, known to be an effective catalyst for hetero Diels-Alder reaction of Danishefsky's diene, showed moderate enantioselectivity (endo: 20 - 52 % ee), although almost no diastereoselectivity was observed. Furthermore, in the presence of the chiral catalyst, which was prepared from 2,6-bis[( 4S )-( - )-isopropyl-2-oxazolin-2-yl]pyridine and Sc( OTf )_3, enantioselectivity of the endo-product showed 86 % ee ( endo : exo = 76 : 24 ). To the best of knowledge, this is the first example of asymmetric induction found in the chiral Lewis acid-catalyzed cycloaddition reaction of a carbonyl ylide.