143880-86-8Relevant articles and documents
A high-throughput screening approach for the determination of additive effects in organozinc addition reactions to aldehydes
Rudolph, Jens,Lormann, Matthias,Bolm, Carsten,Dahmen, Stefan
, p. 1361 - 1368 (2005)
The effects of additives in phenylzinc addition reactions to an aldehyde have been studied using an automated high-throughput screening approach. With 2-bromobenzaldehyde as test substrate and N,N-dibutylnorephedrine (dbne) as chiral ligand, an improvement of 20% ee over the catalyzed reaction in the absence of the additive was observed. The described results enable a novel access towards chiral diarylmethanols using commercially available substrates, reagents and ligands as well as fast, automated techniques.
Isosterically designed chiral catalysts: Rationale, optimization and their application in enantioselective nucleophilic addition to aldehydes
Gao, En,Li, Qiao,Duan, Lili,Li, Lin,Li, Yue-Ming
supporting information, (2020/10/20)
Proline-based N,N′-dioxide ligands were designed on the basis of isosteric approach, and were successfully applied in enantioselective nucleophilic addition to aldehydes. In the presence of 10 mol% of chiral ligand 1b, enantioselective addition of diethylzinc to aldehydes provided the corresponding secondary alcohols in up to 90% isolated yield and up to 99% ee. Similarly, using 3e as chiral ligand, enantioselective arylation and alkynylation of aldehydes also proceeded readily, leading to the desired chiral alcohols in up to 92% isolated yield at 99% ee and 80% isolated yields and up to 84% ee, respectively. The current work would shed light on expanding the structure diversity in the design of chiral ligands and chiral catalysts.
Highly Enantioselective Cobalt-Catalyzed Hydroboration of Diaryl Ketones
Liu, Wenbo,Guo, Jun,Xing, Shipei,Lu, Zhan
, p. 2532 - 2536 (2020/04/02)
A highly enantioselective cobalt-catalyzed hydroboration of diaryl ketones with pinacolborane was developed using chiral imidazole iminopyridine as a ligand to access chiral benzhydrols in good to excellent yields and ee. This protocol could be carried out in a gram scale under mild reaction conditions with good functional group tolerance. Chiral biologically active 3-substituted phthalide and (S)-neobenodine could be easily constructed through asymmetric hydroboration as a key step.
Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
supporting information, p. 8796 - 8801 (2020/11/13)
Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
