Recent advances in earth-abundant transition-metal-catalysed asymmetric oxidative sp3–sp3 cross-couplings

Abstract

Asymmetric sp³–sp³ cross-coupling reactions (including C_sp³–C_sp³, C_sp³–X_sp³ and X_sp³–X_sp³ couplings) represent some of the most modular and straightforward methods to rapidly build saturation with control over stereochemistry by simply connecting two saturated coupling partners. However, asymmetric sp³–sp³ cross-couplings still remain challenging due to the increased steric hindrance and flexibility of coupling partners and intermediates, leading to enhanced competitive side reactions and increased difficulties in sp³–sp³ cross-couplings as well as enantioselectivity control. Over the past decades, earth-abundant transition-metal-catalysed redox-neutral cross-coupling between nucleophiles and electrophiles and reductive cross-coupling between two electrophiles have been developed for building stereogenic centers by sp³–sp³ coupling. In these two reaction modes, stoichiometric electrophiles are required. On the other hand, asymmetric oxidative sp³–sp³ cross-coupling between two nucleophiles offers another alternative to access stereogenic centers by asymmetric sp³–sp³ cross-coupling. This reaction circumvents the use of electrophiles. Over the past years, earth-abundant metal (e.g., Fe, Co, Ni, and Cu)-catalysed asymmetric oxidative sp³–sp³ coupling reactions have achieved great progress for the efficient construction of chiral saturated C–C/X bonds. Thus, this review systematically summarizes research progress in this reaction mode with an emphasis on reaction development, mechanistic investigations, and synthetic applications of different catalytic systems. Moreover, perspectives on future development and key issues to be addressed are also discussed to provide further guidance for this area.