Synthesis and application of axially chiral biscarbolines with functional N-O and sulfone for 1,2-transfer hydrogenations of ketimines

The Development of Organocatalytic Asymmetric Reduction of Carbonyls and Imines Using Silicon Hydrides

“…In 2019, the same group also prepared a series of axially chiral N-O oxides bearing sulfone functional groups and applied them to enantioselective reduction of ketimines. [102] The catalyst 61 with a tertiary butyl group, exhibited highly catalytic efficiency (Scheme 25c). In the same year, axially chiral N-O alcohols, bearing two carboline moieties, were synthesized and utilized in the enantioselective reduction of ketimines and βamino esters.…”

“…In 2019, the same group also prepared a series of axially chiral N‐O oxides bearing sulfone functional groups and applied them to enantioselective reduction of ketimines [102] . The catalyst 61 with a tertiary butyl group, exhibited highly catalytic efficiency (Scheme 25c).…”

Rational Design of Simple Organocatalysts for the HSiCl3 Enantioselective Reduction of (E)-N-(1-Phenylethylidene)aniline

“…The resulting kinetic profiles are presented in Figure 3. Chang-ing the solvent from CH 2 Cl 2 to CHCl 3 in this kind of reaction often provides lower ee values and slower reaction rates [54,[56][57][58], but slower kinetics can enable more accurate NMR kinetic analyses and reduce the contribution of the uncatalyzed reaction. The rate constants were calculated considering a simultaneous contribution of the uncatalyzed and catalyzed reactions with first-order rate equations in both substrate and reagent, in agreement with most mechanistic studies (Scheme 2 and Equation ( 1)) [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”

Evaluation of 3,3′-Triazolyl Biisoquinoline N,N′-Dioxide Catalysts for Asymmetric Hydrosilylation of Hydrazones with Trichlorosilane

“…Since Matsumura's seminal work, that employed N-formylproline-derived catalysts [33,34], and the milestone achieved by Malkov and Kočovský with their N-methyl-L -valine-based catalysts [35][36][37], numerous chiral Lewis-base catalysts have been reported for the asymmetric hydrosilylation of ketimines with trichlorosilane (selected reviews; [30][31][32], selected references; [38][39][40][41][42][43][44][45]). While the majority of these catalysts are amide-based Lewis-bases, other kinds of Lewis-bases are also reported, which includes pyridine N-oxides (selected references; [46][47][48][49][50][51]), phosphine oxides (selected references; [52][53][54]), and sulfinamides (selected references; [55,56]). Despite a plethora of reports in this area, the Lewis-base-catalyzed trichlorosilane-mediated reduction of ketimines currently remains limited to N-aryl and alkyl protected ones (Scheme 1, Equation ( 2)).…”

“…Since Matsumura's seminal work, that employed N-formylproline-derived catalysts [33,34], and the milestone achieved by Malkov and Kočovský with their N-methyl-L-valine-based catalysts [35][36][37], numerous chiral Lewis-base catalysts have been reported for the asymmetric hydrosilylation of ketimines with trichlorosilane (selected reviews; [30][31][32], selected references; [38][39][40][41][42][43][44][45]). While the majority of these catalysts are amide-based Lewis-bases, other kinds of Lewisbases are also reported, which includes pyridine N-oxides (selected references; [46][47][48][49][50][51]),…”