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，并应用于几种重要的光学活性化合物的合成。本研究旨在拓宽环氧化反应的底物范围，开发新型手性配合物，使C-H键的不对称氧化、顺式选择性不对称环丙烷化等重要的不对称反应成为可能。在三年的时间里，我们取得了以下令人印象深刻的成果。用光学活性的（salen）锰配合物催化meso-四氢呋喃的C-H键的对映选择性羟基化反应，选择性高达90%ee。该不对称反应成功地应用于（-）-别育亨宾和（-）-苦马豆素的合成.新合成的顶端带有亚硝酰基的（salen）钌配合物显示出独特的不对称催化作用。在光照条件下，该配合物对2，6-二氯吡啶N-氧化物为末端氧化剂的环氧化反应表现出催化活性。该催化剂不仅对顺式二取代烯烃的环氧化反应具有高的对映选择性，而且对反式烯烃和末端烯烃的环氧化反应也具有高的对映选择性，这与以往报道的（salan）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定向性，生成的环氧化合物没有发生双键几何异构化.利用（salen）钴（II）配合物实现了高顺式和对映选择性的环丙烷化反应。通过这一成果，环丙烷化反应中所有可能的立体化学反应都可以首次得到化学控制。用光学活性的三恶唑啉铜配合物催化外消旋烯烃烯丙基位的不对称C-H氧化反应，对映选择性大于80%ee。

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.