56427-44-2Relevant articles and documents
Zinc-Catalyzed Asymmetric Hydrosilylation of Cyclic Imines: Synthesis of Chiral 2-Aryl-Substituted Pyrrolidines as Pharmaceutical Building Blocks
W?glarz, Izabela,Michalak, Karol,Mlynarski, Jacek
, p. 1317 - 1321 (2020/12/09)
The first successful enantioselective hydrosilylation of cyclic imines promoted by a chiral zinc complex is reported. In situ generated zinc-ProPhenol complex with silane afforded pharmaceutically relevant enantioenriched 2-aryl-substituted pyrrolidines in high yields and with excellent enantioselectivities (up to 99% ee). The synthetic utility of presented methodology is demonstrated in an efficient synthesis of the corresponding chiral cyclic amines, being pharmaceutical drug precursors to the Aticaprant and Larotrectinib. (Figure presented.).
Experimental study of the mechanism of the palladium-catalyzed aryl-alkyl negishi coupling using hybrid phosphine-electron-withdrawing olefin ligands
Gioria, Estefana,Martnez-Ilarduya, Jess M.,Espinet, Pablo
, p. 4394 - 4400 (2015/04/16)
A detailed study of the Negishi cross-coupling reaction of ArI (Ar = 2-C6H4CO2Et) and ZnEt2 with palladium catalysts containing conventional phosphines versus one using a chelating hybrid phosphine-electron-withdrawing olefin (P-EWO) ligand reveals that for conventional phosphines (e.g., PPh3) β-H elimination from intermediate [PdArEt(PPh3)2] is competitive with Ar-Et reductive elimination and is responsible for part of the undesired reduction product ArH. In contrast, with the EWO phosphine, the β-H elimination from intermediate [PdArEt(P-EWO)] is slow compared to the fast Ar-Et reductive elimination, and the undesired reduction product ArH observed proceeds in this case of hydrolysis of ZnArEt, formed in transmetalations where Ar is transferred from Pd to Zn. The rate of these transmetalations is comparable to the rate of reductive eliminations. Consequently, undesired transmetalations affording [PdEt2(P-EWO)] and ZnArEt are more effective at early stages of the reactions and less effective when the ethylating agent becomes poorer in ZnEt2 and richer in ZnEtX (X = I), as the reaction proceeds. Careful analysis of the experiments reveals the detailed changing evolution of the reaction, not only providing the main features of the catalytic cycle but also deducing how the reagents in the system change with time and what the effects on the products of these changes are.
Superior effect of a π-acceptor ligand (phosphine-electron-deficient olefin ligand) in the Negishi coupling involving alkylzinc reagents
Luo, Xiancai,Zhang, Heng,Duan, Hui,Liu, Qiang,Zhu, Lizheng,Zhang, Tony,Lei, Aiwen
, p. 4571 - 4574 (2008/03/12)
(Chemical Equation Presented) Palladium-catalyzed Negishi cross-coupling involving primary and secondary alkyls, even in the presence of β-H, can be achieved at ambient temperature using chelating ligands containing a phosphine and an electron-deficient olefin. The superior effects of the ligands were shown not only in the desired cross-coupling product yields but also in the fast reaction at mild conditions. This reaction has been also scaled up to 50 g in 0.005 mol % catalyst (20,000 TONs) at room temperature.
