485-65-4Relevant articles and documents
Enantioselective photooxygenation of β-dicarbonyl compounds in batch and flow photomicroreactors
Tang, Xiao-Fei,Zhao, Jing-Nan,Wu, Yu-Feng,Zheng, Ze-Hao,Feng, Shi-Hao,Yu, Zong-Yi,Liu, Guang-Zhi,Meng, Qing-Wei
supporting information, p. 7938 - 7942 (2019/09/06)
A series of C-2′ modified cinchonine-derived phase-transfer catalysts were synthesized and used in the enantioselective photo-organocatalytic aerobic oxidation of β-dicarbonyl compounds with excellent yields (up to 97%) and high enantioselectivities (up to 90% ee). Furthermore, the reaction was carried out in a flow photomicroreactor, in which the heterogeneous gas-liquid-liquid asymmetric photocatalytic oxidation reaction was performed affording good yields (up to 97%) and enantioselectivities (up to 86% ee) within 0.89 min.
Transfer hydrogenations of alkenes with formate on Pd/C: Synthesis of dihydrocinchona alkaloids
Wu, Haotian,Hintermann, Lukas
, p. 888 - 892 (2013/05/09)
Protocols for preparative (1-80 gram scale) transfer hydrogenations of alkenes over a palladium on carbon catalyst using formic acid/ammonium formate as hydrogen donor are presented. Cinchona alkaloids have been converted to their dihydro derivatives in >94% yield. Georg Thieme Verlag Stuttgart - New York.
Asymmetric direct α-hydroxylation of β-Oxo esters by phase-transfer catalysis using chiral quaternary ammonium salts
Lian, Mingming,Li, Zhi,Du, Jian,Meng, Qingwei,Gao, Zhanxian
supporting information; experimental part, p. 6525 - 6530 (2011/02/25)
The first enantioselective direct α-hydroxylation of β-oxo esters was developed by using phase-transfer catalysis. 1-Indanone-derived 1-adamantyl (1-Ad) β-oxo esters, in the presence of commercially available cumyl hydroperoxide and a cinchonine-based ammonium salt, resulted in the corresponding products with 69-91 % yield and 65-74 % ee. The reaction had also been successfully scaled-up to a gram quantity, and a similar yield was obtained without loss of the enantioselectivity. Copyright
Indium-mediated catalytic enantioselective allylation of N -benzoylhydrazones using a protonated chiral amine
Kim, Sung Jun,Jang, Doo Ok
supporting information; experimental part, p. 12168 - 12169 (2010/10/03)
A catalytic enantioselective indium-mediated allylation of N-benzoylhydrazones in conjunction with a protonated chiral amine affording enantioenriched homoallylic amines with an extremely high level of enantioselectivity and chemical yield was developed.
Highly enantioselective radical addition to N-benzoyl hydrazones using chiral ammonium salts
Doo, Ok Jang,Sang, Yoon Kim
supporting information; experimental part, p. 16152 - 16153 (2009/05/08)
In the presence of a protonated cinchonine derivative, radical addition reactions proceeded efficiently, affording addition adducts in high yields with an extremely high enantioselectivity. The chiral ammonium salt was recyclable after a simple aqueous workup. The reaction provides environmentally benign reaction conditions. Copyright
The rational design of modified Cinchona alkaloid catalysts. Application to a new asymmetric synthesis of chiral chromanes
Merschaert, Alain,Delbeke, Pieter,Daloze, Désiré,Dive, Georges
, p. 4697 - 4701 (2007/10/03)
A new asymmetric synthesis of 2-substituted chiral chromanes has been achieved. The key step is the intramolecular conjugate addition of a phenolic nucleophile on a α,β-unsaturated ester catalyzed by Cinchona alkaloids. The high ee's obtained with cinchonine and its derivatives have been rationalized by ab initio quantum chemistry calculations of transition state structures.
Heterogeneous Enantioselective Hydrogenation of Activated Ketones Catalyzed by Modified Pt-Catalysts: A Systematic Structure-Selectivity Study
Exner, Christian,Pfaltz, Andreas,Studer, Martin,Blaser, Hans-Ulrich
, p. 1253 - 1260 (2007/10/03)
A systematic structure-selectivity study was carried out for the enantioselective hydrogenation of activated ketones with chirally modified Pt/Al2O3 catalysts. For this, 18 modifiers containing an extended aromatic system able to form a strong adsorption complex with the Pt surface, and a suitable chiral group with an amino function capable to interact with the keto group of the substrate (HCd, Qd, HCn, Qn, and semi-synthetic derivatives, as well as synthetic analogues) were prepared and tested on 8 different activated ketones in AcOH and toluene under standard conditions. It was found that relatively small structural changes of the substrate and/or modifier structures strongly affected the enantioselectivity, and that no "best" modifier exists for all substrates. The highest ees for all substrates were obtained with quinuclidine-derived modifiers in combination with naphthalene or quinoline rings, either in AcOH (substrates 1-5 and 8, all carrying an sp3 carbon next to the keto group) or toluene (6 and 7, with an sp2 carbon next to the ketone). The presence and nature of the substituent R′ at the quinuclidine significantly affected the ee (positive and negative effects). Certain combinations of an aromatic system and an amino function were preferred: For the quinuclidine moiety, quinoline and to a somewhat lesser extent naphthalene were a better match, while for the pyrrolidinylmethyl group anthracene was better suited. Methylation of the OH group often had a positive effect for hydrogenations in AcOH but not in toluene. With the exception of 8, higher ees were obtained for the Cd/ Qn series [leading to (R)-products] than for the Cn/ Qd series [leading to (S)-products]. In several cases, opposite structure-selectivity trends were detected when comparing reactions in toluene and AcOH, indicating a significant influence of the solvent.
STEREOSPECIFIC SYNTHESIS OF ERYTHRO CINCHONA ALKALOIDS FROM SECOLOGANIN
Brown, Richard T.,Curless, Dale
, p. 6005 - 6008 (2007/10/02)
A short, diastereoselective synthesis of (+)-dihydrocinchonine (7) and (-)-dihydrocinchonidine (8) from their biogenetic precursor, secologanin (1a), and lepidine has been achieved in 28percent overall yield.
