Recent advances with cobalt-mediated asymmetric hydrogenations

Asymmetric hydrogenation using homogeneous catalysts is one of the unique synthetic strategies for generating enantiopure saturated compounds from their prochiral unsaturated starting materials. Early attempts toward asymmetric hydrogenations involving the use of various noble metals such as Ru, Rh, and Ir have been used in such transformations efficiently. These noble metals are extremely scarce elements, occurring at very low abundances in the earth's crust (5 × 10−5 to10−4 ppm). It remains a long-term problem for their wide usability because of their high cost and low abundance of these metal catalysts. The cost-effective catalysts while considering precious metals to earth-abundant metals such as cobalt complexes have shown their prominent reactivity in recent days. This review compiles especially the development of novel cobalt-mediated chiral complexes and their utility in the asymmetric hydrogenation of various unsaturated compounds. The review aims to collect valuable insights from various research groups into one location, the scope, and the promises of cobalt-catalyzed asymmetric hydrogenation to provide a quick, updated, and appealing overview.