N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitrites and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v using Ir-(S,S)-f binaphane as catalyst provides chiral amines 4a-4v in 90-95% yield with enantioselectivities up to 95% ee.
N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitrites and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v using Ir-(S,S)-f binaphane as catalyst provides chiral amines 4a-4v in 90-95% yield with enantioselectivities up to 95% ee.
Synthesis of Sterically Hindered Primary Amines by Concurrent Tandem Photoredox Catalysis
作者:Michael C. Nicastri、Dan Lehnherr、Yu-hong Lam、Daniel A. DiRocco、Tomislav Rovis
DOI:10.1021/jacs.9b10871
日期:2020.1.15
methodologies exist for amine synthesis, but the direct synthesis of primary amines with a fully substituted α carbon center is an underdeveloped area. We report a method which utilizes photoredox catalysis to couple readily available O-benzoyl oximes with cyanoarenes to synthesize primary amines with fully substituted α-carbons. We also demonstrate that this method enables the synthesis of amines with α-trifluoromethyl
Catalytic diastereo- and enantioselective additions of versatile allyl groups to N–H ketimines
作者:Hwanjong Jang、Filippo Romiti、Sebastian Torker、Amir H. Hoveyda
DOI:10.1038/nchem.2816
日期:2017.12
and/or enantioselectively are much sought after. Various methods for enantioselective synthesis of α-secondary amines are available (for example, from additions to protected/activated aldimines), but those involving ketimines are much less common. There are no reported additions of carbon-based nucleophiles to unprotected/unactivated (or N–H) ketimines. Here, we report a catalytic, diastereo- and enantioselective
Electrochemical Synthesis of Hindered Primary and Secondary Amines via Proton-Coupled Electron Transfer
作者:Dan Lehnherr、Yu-hong Lam、Michael C. Nicastri、Jinchu Liu、Justin A. Newman、Erik L. Regalado、Daniel A. DiRocco、Tomislav Rovis
DOI:10.1021/jacs.9b10870
日期:2020.1.8
Accessing hindered amines, particularly primary amines α to a fully substituted carbon center, is synthetically challenging. We report an electrochemical method to access such hindered amines starting from benchtop-stable iminium salts and cyanoheteroarenes. A wide variety of substituted heterocycles (pyridine, pyrimidine, pyrazine, purine, azaindole) can be utilized in the cross-coupling reaction
Rhodium-Catalyzed Asymmetric Hydrogenation of Unprotected NH Imines Assisted by a Thiourea
作者:Qingyang Zhao、Jialin Wen、Renchang Tan、Kexuan Huang、Pedro Metola、Rui Wang、Eric V. Anslyn、Xumu Zhang
DOI:10.1002/anie.201404570
日期:2014.8.4
Asymmetrichydrogenation of unprotected NH imines catalyzed by rhodium/bis(phosphine)‐thiourea provided chiral amines with up to 97 % yield and 95 % ee. 1H NMR studies, coupled with control experiments, implied that catalytic chloride‐bound intermediates were involved in the mechanism through a dual hydrogen‐bonding interaction. Deuteration experiments proved that the hydrogenation proceeded through
由铑/双(膦)-硫脲催化的未保护的NH亚胺的不对称氢化提供了手性胺,产率高达97%,ee值高达95% 。1 H NMR 研究与对照实验相结合,表明催化氯化物结合中间体通过双氢键相互作用参与了该机制。氘化实验证明氢化反应是通过与亚胺一致的途径进行的。
Chiral Brønsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH–Imine Hydrochloride Salts
作者:Benjamin List、Vijay N. Wakchaure、Carla Obradors
DOI:10.1055/s-0040-1706413
日期:2020.10
are frequently used substrates in asymmetric Bronsted acid catalysis, their corresponding salts are generally considered unsuitable reaction partners. Such processes are challenging because they require the successful competition of a catalytic amount of a chiral anion with a stoichiometric amount of an achiral one. We now show that enantiopure disulfonimides enable the asymmetric reduction of N–H imine