Lutidine‐Based Chiral Pincer Manganese Catalysts for Enantioselective Hydrogenation of Ketones

Abstract

Aseries of Mn I complexes containing lutidine-based chiral pincer ligands with modular and tunable structures has been developed. The complex shows unprecedentedly high activities (up to 9800 TON; TON = turnover number), broad substrate scope (81 examples), good functional-group tolerance,a nd excellent enantioselectivities (85-98 %e e) in the hydrogenation of various ketones.T hese aspects are rare in earth-abundant metal catalyzedhydrogenations.T he utility of the protocol have been demonstrated in the asymmetric synthesis of av ariety of key intermediates for chiral drugs. Preliminary mechanistic investigations indicate that an outersphere mode of substrate-catalyst interactions probably dominates the catalysis.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

“…Specifically, in addition to aminopincer ligands, the diamino triazine-based pincers B and lutidine-derived PNN pincer C ligands were introduced to Mn-catalyzed hydrogenations by the groups of Kempe 28 and Milstein 29 , and saw further improvement in recent years 30 . In addition to pincer ligands, several bidentate ligands have been employed in Mn catalysis.…”

Ni-catalyzed asymmetric hydrogenation of N-aryl imino esters for the efficient synthesis of chiral α-aryl glycines

“…1b) [28][29][30] . In view of current interest in the development of earthabundant metal catalysts in asymmetric hydrogenation [31][32][33][34][35][36][37][38][39][40][41] , which are inexpensive and environmentally friendly, the use of nickel has drawn increasing attention 24,[31][32][33][34][35][36][37][38][39][40][41] . Although Nicatalyzed asymmetric reduction has seen rapid development, the asymmetric hydrogenation of imines is still in its infancy 24,[42][43][44] .…”

Manganese‐Catalyzed anti‐Selective Asymmetric Hydrogenation of α‐Substituted β‐Ketoamides

“…The origin of the stereoselectivity was rationalized by DFT calculations [17] on the stereochemistry-determining hydride/proton transfer step based on an outer-sphere mechanism, [13] exemplified by the concomitant transfer of the hydride from Mn (Mn-H) and the proton from the nitrogen (N-H) of the ligand to the keto-carbonyl group of (R)-or (S)ketoamide 2 a. Four diastereoisomeric transition states [TS-(SR), TS-(RS), TS-(SS), and TS-(RR)] were found to be viable (Figure 2), of which TS-(SR) was the most favorable, Table 3: Hydrogenation of racemic a-aryl b-ketoamides 4.…”