Ir-Catalyzed Asymmetric Hydrogenation of Unprotected Indoles: Scope Investigations and Mechanistic Studies

Asymmetric hydrogenation of dibenzo-fused azepines with chiral cationic ruthenium diamine catalysts

“…Notably, a highly efficient asymmetric hydrogenation of the dibenzo-fused azepine hydrochlorides (X = O, CH 2 ) was developed with up to >99% ee by using the chiral Rh/bisphosphine-thiourea ligands. 10 Despite these remarkable advances achieved in this field, further pursuit of a general and phosphine-free catalytic system for the synthesis of structurally diverse chiral dihydrodibenzo-fused azepines is still highly desirable.…”

Facile access to chiral γ-butyrolactones via rhodium-catalysed asymmetric hydrogenation of γ-butenolides and γ-hydroxybutenolides

“…11 The Buchwald group reported a CuH-catalysed enantioselective conjugate reduction of γ-butenolides; 12 however, the requirement of using high catalyst loading and a strong base additive could limit the application of this method in organic synthesis and the pharmaceutical industry. Recently, our group developed a bisphosphine-thiourea chiral ligand, ZhaoPhos, 13 which exhibited extraordinary potential in rhodium 14 and iridium-catalyzed 15 asymmetric hydrogenation due to its powerful hydrogen-bonding and anion-binding ability resulting from the thiourea moiety. Inspired by this novel strategy, we herein demonstrated a Rh/ZhaoPhos catalysed asymmetric hydrogenation of easily accessible γ-butenolides and γ-hydroxybutenolides, which could be a straightforward method of approaching chiral γ-butyrolactones with excellent catalytic results (Scheme 1b).…”

Ru-NHC-Catalyzed Asymmetric, Complete Hydrogenation of Indoles and Benzofurans: One Catalyst with Dual Function

“…Octahydroindoles are important structural motifs, prevalent in many marketed drugs, , natural products, , bioactive molecules, and organocatalysts (Figure e). , Therefore the development of synthetic methods for chiral octahydroindoles is of high importance. − Although there are some reports on the asymmetric partial hydrogenation of indoles, − however, to the best of our knowledge, chiral octahydroindoles have not been accessed via complete, enantioselective hydrogenation of indoles despite the straightforwardness of the transformation. − Therefore, we proposed a novel enantioselective hydrogenation utilizing dual catalysis driven by a single metal complex to access chiral octahydroindoles. Our group previously developed a Ru-chiral carbene catalyst (Ru­(( R , R )-SINpEt) 2 ) with excellent reactivity and enantioselectivity in the hydrogenation of heterocyclic aromatic compounds. ,− Drawing on the reported literature and our research on carbene chemistry, we envisioned that metal–carbene complexes could be promising to fulfill the requirements for an in situ transformable catalyst since these complexes can be converted into nanosized heterogeneous particles. ,− We herein report highly enantioselective and diastereoselective complete hydrogenation of indoles, using Ru­(( R , R )-SINpEt) 2 as a dual functional catalyst, to synthesize a wide range of chiral octahydroindoles (Figure c).…”