83001-27-8Relevant academic research and scientific papers
Enantioselective synthesis of tunable chiral pyridine-aminophosphine ligands and their applications in asymmetric hydrogenation
Liu, Youran,Chen, Fei,He, Yan-Mei,Li, Chenghao,Fan, Qing-Hua
supporting information, p. 5099 - 5105 (2019/05/29)
A small library of tunable chiral pyridine-aminophosphine ligands were enantioselectively synthesized based on chiral 2-(pyridin-2-yl)-substituted 1,2,3,4-tetrahydroquinoline scaffolds, which were obtained in high yields and with excellent enantioselectivities via ruthenium-catalyzed asymmetric hydrogenation of 2-(pyridin-2-yl)quinolines. The protocol features a wide substrate scope and mild reaction conditions, enabling scalable synthesis. These chiral P,N ligands were successfully applied in the Ir-catalyzed asymmetric hydrogenation of benchmark olefins and challenging seven-membered cyclic imines including benzazepines and benzodiazepines. Excellent enantio- and diastereoselectivity (up to 99% ee and >20:1 dr), and/or unprecedented chemoselectivity were obtained in the asymmetric hydrogenation of 2,4-diaryl-3H-benzo[b]azepines and 2,4-diaryl-3H-benzo[b][1,4]diazepines.
SELECTIVE SUBSTITUTION OF UNPROTONATED PYRIDINES BY ALKYL RADICALS
Chianelli, D.,Testaferri, L.,Tiecco, M.,Tingoli, M.
, p. 657 - 663 (2007/10/02)
The reactions of dioxanyl and cyclohexyl radicals with 2- and 3-X-pyridines (X=CN, COMe, CO2Me) give a single substitution product deriving by addition at the 5- and 6-position respectively; with 4-X-pyridines substitution occurs preferentially at the 3-position.If the reactions are carried out with protonated pyridines other positional isomers are obtained.From the synthetic point of view the two procedures are therefore complementary.The change in positional selectivity on passing from unprotonated to protonated aromatic substrates is discussed and interpreted on the basis of the different nature of the transition state of the addition step.
