Calcium (Ca) is one of the most abundant elements on the earth and it is easily accessible and is very cheap. In comparison with transition-metal elements, Ca is biocompatible and environment-friendly. Therefore, the reactions by using Ca compounds are of good prospect of large-scale production and application. During the last decade, investigations on organocalcium catalysis are just unfolding. Beside conventional Ca salts with strong electron-withdrawing counter anions that may serve as Lewis acid catalysts, many Ca complexes have also been designed recently and found to be good catalysts like transition-metal catalysts. Compared with the conventional inorganic base such as NaOH and KOH, Ca(OH)2 was uniquely active in some reactions. These findings are interesting and may attract continuous attentions of the chemists. Owning to the great abundance, non-toxicity, and biocompatible features of Ca element, Ca-catalyzed reactions are of great application values from the viewpoint of industry as well.
On the other hand, the hydrofunctionalization reactions of element-H (including O-H, S-H, N-H, P-H, C-H, Si-H, B-H, H-H etc) are significant synthetic reactions. By using these reactions, the precise and efficient functionalization of organic compounds can be achieved without the generation of wastes. Thus, in line with the calls of environment protection, the hydrofunctionalization reactions of element-H are good tools to improve the traditional synthetic procedures and reduce the damages of chemical production to the environments. The conventional hydrofunctionalization reactions usually employ transition-metal catalysts, such as Pd, Rh, Ru, Cu, Ni etc, which are expensive, toxic and unfriendly to the environments. Therefore, developing even cheaper and environment-friendly catalysts to achieve the hydrofunctionalization reactions are of good practical values.
Recently, the organocalcium-catalyzed hydrofunctionalization reactions of element-H are widely investigated and have been reported by a series of literatures. Classified by the types of element-H, this short review summarizes the recent advances of organocalcium-catalyzed hydrofunctionalization reactions. The authors hope that it may provide a useful guide for interested readers from both the academy and industry.
This work was supported by the National Natural Science Foundation of China (NSFC) and Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions etc.
See the article:
Lei Yu, Rongrong Qian, Xin Deng, Fang Wang, Qing Xu. Calcium-catalyzed reactions of element-H bonds. Science Bulletin, 2018, 63(15): 1010-1016