Remarkable progress has been made in the catalytic reactions promoted by MHAT in recent years. Notably, enantioselectivity remains a challenge because this mechanism involves highly reactive carbon radicals. Even for reactions outside the MHAT system, enantioselective reactions via carbon radicals are limited. In 2016, we reported the intramolecular hydroalkoxylation of 1a to afford cyclic ether 2a in 28%ee using chiral -ketoiminato cobalt complex C12, (Me2SiH)2O, and N-fluoropyridinium salt. For enantioselectivity to be observed, the chiral cobalt complex must be involved in the C-O bond forming step. Pronin reported the same concept during our investigation of the enantioselective MHAT/RPC reaction. The researchers developed a catalytic asymmetric intramolecular hydroalkoxylation using an originally developed chiral cobalt complex. In this review, we discuss how our findings differ from those of Pronin et al. in several respects. After extensive optimization of the reaction conditions, we found that the chiral cobalt complex, silyl hydride, and solvent had a significant influence on both the yield and enantioselectivity. In our initial investigation, we discovered the high potential of the Katsuki ligand for the enantioselective MHAT/RPC reaction (Table ). Further optimization based on the Katsuki ligand indicated that C14 produced better results than those of C12 and C13 and the axial chirality of the biphenyl moiety played an important role in selectivity. The enantioselectivity improved by introducing a substituent in the diamine moiety (C15), and 2a was successfully obtained with 93%ee using ligand C16, which contained cyclohexanediamine. At the beginning of the study, we speculated that silylhydride would have little effect on the enantioselectivity because it could possibly have been the hydrogen source of the cobalt hydride species. However, our extensive investigation revealed that the silylhydride has a significant impact on enantioselectivity. (Me2SiH)2O displayed only moderate enantioselectivity (58%ee), whereas secondary silanes markedly improved the enantioselectivity, with diethylsilane providing the best result. Most noteworthy in this study is that the absolute configuration of the major product was different for tertiary and secondary silanes. This influence on the absolute configuration of the major product is surprising from the perspective of the reaction mechanism. Among the secondary silanes, i Pr2SiH2 had the same absolute configuration of the major product of the tertiary silanes (50%ee). Therefore, we examined the effect of the silyl hydride to elucidate the detailed reaction mechanism. Table We therefore investigated the effect of the rate of addition of silylhydride on enantioselectivity. Et2SiH2 was added over 2 hours, resulting in a decrease in enantioselectivity. Upon using CyMeSiH2 as a different secondary silane, to the enantioselectivity decreased to 61%ee over 2 hours. Eventually, the absolute configuration of the major product was reversed over 80 hours. This result suggests that the concentration of intermediates downstream of the cobalt hydride has a significant impact on the enantioselectivity and that multiple enantioselectivity-determining steps may be in competition.