Exploitation of Practical Method for Asymmetric Functionalization of Alkenes

我们研究了光学活性（salen）锰配合物的不对称环氧化反应，并应用于几种光学活性重要化合物的合成。在本研究项目中，我们旨在扩大环氧化反应的底物范围，开发新的手性配合物，以实现一些重要的不对称反应，如C-H键的不对称氧化，顺式选择性不对称环丙烷化。三年来，我们取得了以下令人瞩目的成绩：发现中四氢呋喃的C-H键的羟基化以高选择性（高达90% ee）进行，以光学活性（salen）锰配合物作为催化剂。该不对称反应成功地合成了(-)-异育亨贝恩和(-)-马尾松素。新制备的顶端含亚硝基的（salen）钌配合物具有独特的不对称催化作用。在辐照下，以2,6 -二氯吡啶n -氧化物为末端氧化剂的配合物表现出催化环氧化的活性。不仅对顺式二取代烯烃的环氧化反应有很高的对映选择性，而且对反式和末端烯烃的环氧化反应也有很高的对映选择性，这与以前报道的（萨兰）锰配合物催化的环氧化反应不同。此外，该反应具有高度的立体特异性，生成的环氧化合物没有双键的异构化。采用（salen）钴（II）配合物实现了高顺、对映选择性环丙烷化反应。通过这一成果，环丙烷化过程中所有可能的立体化学都可以首次被化学控制。旋光性三（恶唑啉）铜配合物在外消旋烯烃烯丙基位置的不对称C-H氧化反应中具有80%以上的对映选择性。

We have studied asymmetric epoxidation using optically active (salen)manganese complexes and applied for the synthesis of several optically active important compounds. In this research project, we aimed at extension of the scope of substrates used in the epoxidation and exploitation of new chiral complexes to enable several important asymmetric reactions such as asymmetric oxidation of C-H bond, cis-selective asymmetric cyclopropanation. During three years, we could receive following impressive results.1. Enantioselective hydroxylation of C-H bond of meso-tetrahydrofurans was found to proceed with high selectivity (up to 90% ee) by using optically active (salen)manganese complex as a catalyst. This asymmetric reaction was successfully applied to the synthesis of (-)- Alloyohimbane and (-)-Swainsonine.2. Newly prepared (salen)ruthenium complex bearing nitrosyl group at the apical position was found to show unique asymmetric catalysis. Under the irradiation, the complex showed catalytic activity for epoxidation by using 2, 6-dichloropyridine N-oxide as a terminal oxidant. High enantioselectivity was observed not only for the epoxidation of cis-disubstituted olefins but also that of trans- and terminal olefins differing from the previously reported epoxidation catalyzed by (salan)manganese complex. Furthermore, the reaction was highly stereospecific and produced epoxides without isomerization of the geometry of double bond.3. Highly cis- and enantio-selective cyclopropanation was realized by using (salen)cobalt(II) complex. By this achievement, all the possible stereochemistry in cyclopropanation could be for the first time controlled chemically.4. High enantioselectivity more than 80% ee could be observed in the asymmetric C-H Oxidation at a allylic position of racemic olefins by using optically active tris(oxazoline)copper complex.