211874-85-0Relevant academic research and scientific papers
Enantioselective Alkynylation of 2-Trifluoroacetyl Imidazoles Catalyzed by Bis-Cyclometalated Rhodium(III) Complexes Containing Pinene-Derived Ligands
Zheng, Yu,Harms, Klaus,Zhang, Lilu,Meggers, Eric
, p. 11977 - 11981 (2016)
Chiral rhodium(III) complexes containing two cyclometalating 2-phenyl-5,6-(S,S)-pinenopyridine ligands and two additional acetonitriles are introduced as excellent catalysts for the highly enantioselective alkynylation of 2-trifluoroacetyl imidazoles. Whe
Pinene-derived monodentate phosphoramidites for asymmetric hydrogenation
Schmitz, Christian,Leitner, Walter,Franciò, Giancarlo
, p. 2889 - 2901 (2015/04/27)
Phosphoramidite ligands based on pinene-derived chiral amines have been prepared by a straightforward procedure in good yields. The key step of the synthetic protocol is a stereoselective hydrogenation of annulated pinene-pyridine derivatives leading to (diastereoisomeric) secondary amines that were separated and treated with different chlorophosphites to yield the envisaged phosphoramidites. The absolute configurations of the ligands were assigned on the basis of NMR analyses and corroborated by X-ray diffraction analysis of a borane adduct of a typical ligand. The new ligands were employed in the asymmetric hydrogenation of imines and olefins. The iridium-catalyzed hydrogenation of imines provided up to 81?% ee, whereas in the rhodium-catalyzed hydrogenation of functionalized olefins enantioselectivities of up to 99?% ee were achieved. In this particular application, the different chiral elements of the ligand structure led to synergistic effects and the enantioselectivity is dominated by the chiral diol moiety.
Mechanistic dichotomy in the asymmetric allylation of aldehydes with allyltrichlorosilanes catalyzed by chiral pyridine N-oxides
Malkov, Andrei V.,Stoncius, Sigitas,Bell, Mark,Castelluzzo, Fabiomassimo,Ramirez-Lopez, Pedro,Biedermannova, Lada,Langer, Vratislav,Rulisek, Lubomir,Kocovsky, Pavel
, p. 9167 - 9185 (2013/07/26)
Detailed kinetic and computational investigation of the enantio- and diastereoselective allylation of aldehydes 1 with allyltrichlorosilanes 5, employing the pyridine N-oxides METHOX (9) and QUINOX (10) as chiral organocatalysts, indicate that the reaction can proceed through a dissociative (cationic) or associative (neutral) mechanism: METHOX apparently favors a pentacoordinate cationic transition state, while the less sterically demanding QUINOX is likely to operate via a hexacoordinate neutral complex. In both pathways, only one molecule of the catalyst is involved in the rate- and selectivity-determining step, which is supported by both experimental and computational data. Copyright
New monoterpene-derived phosphinopyridine ligands and their application in the enantioselective iridium-catalyzed hydrogenation
Chelucci, Giorgio,Marchetti, Mauro,Malkov, Andrei V.,Friscourt, Frédéric,Swarbrick, Martin E.,Ko?ovsky, Pavel
, p. 5421 - 5431 (2011/08/06)
Pyridine derivatives with a phosphine or phosphinite pendant (1-11) have been synthesized from (+)-α-pinene, (-)-isopinocampheol, and/or (+)-camphor via Kro?hnke annulation or another annulation method as the key step for the construction of the pyridine nucleus. The iridium complex of 6 proved to catalyze hydrogenation of the prochiral unfunctionalized alkene 44 with 94% ee, whereas the complex of 2 was most efficient in the hydrogenation of the cinnamyl-type ester 45 (83% ee).
Chiral aryl pyridyl alcohols as enantioselective catalysts in the addition of diethylzinc to substituted benzaldehydes
Chang, Tien-Chu,Chen, Chinpiao
experimental part, p. 606 - 615 (2009/05/11)
Chiral (5-aryl-10,10-dimethyl-6-aza-tricyclo[7.1.1.02,7]undeca- 2(7),3,5-trien-8-yl)-diphenyl-methanols were prepared from highly enantiopure (1R)-(+)-α-pinene (> 97% ee), and applied in the enantioselective addition of diethylzinc to substitut
