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

在10%稀土三氟酸盐的催化下，重氮乙酸异丙酯与醇的反应顺利进行，高产率地得到了所需的α，α取代产物。在L与苯基重氮乙酸薄荷酯的反应中获得了中等的非对映选择性。将联萘酚、联二亚胺等具有轴手性的配体与稀土金属三氟化物混合制成的催化剂，在选择性和化学产率方面并不理想。此外，还考察了在Rh_2(OAc)_4催化分解邻甲氧基甲酰基-α-重氮二苯乙酮生成的2-苯并苯并-4-吡喃的反应中，使用Lewis酸进行立体控制的反应。在苯中回流下与N-取代马来酰亚胺的反应表现出外选择性，而在室温下Yb(OTf)_3在CH_2Cl2中的存在下具有较高的内选择性。另一方面，在Et_2O或CH_2Cl_2中，加入10mol%的Yb(OTf)_3对苯甲醛、对取代苯甲醛和苯氧基乙醛的反应具有很高的选择性。我们还发现，使用10mol%的稀土元素三(S)-1，1‘-联萘-2，2’-二基磷酸，虽然几乎没有观察到非对映选择性，但表现出中等的对映选择性(Endo：20-52%ee)。此外，在由2，6-双[(4S)-(-)-异丙基-2-恶唑啉-2-基]吡啶和Sc(OTf)_3制备的手性催化剂存在下，内切产物的对映选择性为86%ee(endo：exo=76：24)。据所知，这是在手性Lewis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.