Ruthenium-Catalyzed Direct Carbonylation at C-H Bonds

科学研究补助金（B）的目的是开发C-H键上的直接羰基化反应，并根据从直接羰基化反应研究中获得的知识开发新的催化反应。结果发现，咪唑与CO和烯烃反应中，在C-H键的α-sp^2位氮上发生了钌催化的羰基化反应。我们发现，其他五元N-杂芳族化合物，如恶唑，噻唑和吡唑也可以用于羰基化反应。底物的反应性对应于底物的共轭酸的pKa。底物的pKa值越高，反应活性越高，我们已经报道了吡啶基苯与CO和烯烃反应中，吡啶环作为导向基团，在C-H键邻位上的羰基化反应。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，甚至在1个大气压的CO下也能进行羰基化反应，迄今为止我们所发现的羰基化反应都是在sp^2 C-H键上进行的。发现烷基胺中与氮原子α位的sp^3 C-H键在铑络合物催化下可以发生羰基化反应。

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.