Ruthenium-Catalyzed Direct Carbonylation at C-H Bonds

科学研究补助金(B)的目的是开发C-H键上的直接羰化反应，并根据从直接羰化反应研究中获得的知识开发新的催化反应。结果发现：在咪唑与CO和烯烃的反应中，我们已经报道了Ru催化的C-H键α上的羰基化反应。我们发现，其他五元N-杂芳烃，如恶唑、噻唑、吡唑等也可用于羰化反应。底物的反应活性对应于底物的共轭酸的pKa。底物的pKa越高，反应的活性就越高。我们已经报道了吡啶苯与CO和烯烃的反应中，Ru催化的C-H键邻位的羰基化反应，其中吡啶环为导向基团。研究发现，恶唑啉环也可以作为羰基化反应的导向基团。在某些底物中，即使在CO为1大气压的情况下，该反应也可以进行。到目前为止，我们所发现的所有的羰基化反应都是在sp2 C-H键上进行的。结果表明，在催化剂的存在下，烷基胺中的氮原子与α上的sp^3C-H键发生了羰基化反应。

The purpose of Grant-in-Aid for Scientific Research (B) was the development of direct carbonylation at C-H bonds and the development of new catalytic reactions based on the knowledge obtained from the research on the direct carbonylation reactions. As a result, we found the following results.We have already reported the ruthenium-catalyzed carbonylation at C-H bonds α to the sp^2 nitrogen in the reaction of imidazoles with CO and olefins. We found that other five-membered N-heteroaromatic compounds, such as oxazoles, thiazoles, and pyrazoles can also be used for the carbonylation reaction. The reactivity of the substrates corresponds to the pKa of the conjugate acid of the substrates. The higher pKa of the substrates, the higher is the reactivity.We have already reported the ruthenium-catalyzed carbonylation at C-H bond ortho position in the reaction of pyridylbenzenes with CO and olefins, in which the pyridine ring acts as a directing group. It is found that an oxazoline ring can also act as a directing group for the carbonylation reaction. The reaction can proceed even at 1 atm of CO in some substrates.All of carbonylation reactions we found thus far are carbonylation at sp^2 C-H bonds. It is found that sp^3 C-H bonds α to the nitrogen atom in alkylamines can be carbonylated in the presence of a rhodium complex as the catalyst.