Pd-Catalyzed Enantioselective C–H Iodination: Asymmetric Synthesis of Chiral Diarylmethylamines
摘要:
An enantioselective C-H iodination reaction using a mono-N-benzoyl-protected amino acid has been developed for the synthesis of chiral diarylmethylamines. The reaction uses iodine as the sole oxidant and proceeds at ambient temperature and under air.
(Pentamethylcyclopentadienyl)cobalt(III)-Catalyzed Oxidative [4+2] Annulation of NH Imines with Alkynes: Straightforward Synthesis of Multisubstituted Isoquinolines
作者:Shang-Shi Zhang、Xu-Ge Liu、Shi-Yong Chen、Dong-Hang Tan、Chun-Yong Jiang、Jia-Qiang Wu、Qingjiang Li、Honggen Wang
DOI:10.1002/adsc.201600025
日期:2016.5.19
A synthetic method for isoquinoline synthesis via a [4+2] annulation of NH imines with alkynes using the high‐valent (pentamethylcyclopentadienyl)cobalt(III) [Cp*Co(III)] catalyst is described. Cerium(IV) sulfate was found to be an efficient oxidant in lieu of the commonly used copper or silver salts. Broad substrate scope, high functional group tolerance, and generally good yields were observed.
An umpolung approach to amides via hypervalentiodine-mediatedoxidative rearrangement of N–H ketimines under mild reaction conditions is described. This strategy provides target amides with excellent selectivity in good yields. In addition, preliminary mechanistic studies demonstrated that the migration preference depends on both steric and electronic effects of the migrating groups.
N–O Bond as External Oxidant in Group 9 Cp*M(III)-Catalyzed Oxidative C–H Coupling Reactions
作者:Xu-Ge Liu、Hui Gao、Shang-Shi Zhang、Qingjiang Li、Honggen Wang
DOI:10.1021/acscatal.7b00677
日期:2017.8.4
catalyzed by group 9 Cp*M(III) complexes. By using Cp*Rh(III)-catalyzed isocoumarin synthesis as a model reaction, experimental and theoretical mechanistic studies were conducted. The results concluded that the Rh(III)–Rh(I)–Rh(III) rather than the Rh(III)–Rh(V)–Rh(III) pathway is more likely involved in the mechanism, and both the C–H activation and oxidation of the Cp*Rh(I) species were involved in
Visible-Light Photoredox-Catalyzed Iminyl Radical Formation by N–H Cleavage with Hydrogen Release and Its Application in Synthesis of Isoquinolines
作者:Wan-Fa Tian、Dang-Po Wang、Shao-Feng Wang、Ke-Han He、Xiao-Ping Cao、Yang Li
DOI:10.1021/acs.orglett.8b00193
日期:2018.3.2
An unprecedented visible-light photoredox-catalyzed iminyl radical formation by N-H cleavage with H2 release has been developed. Itsapplication in the synthesis of various isoquinolines and related polyaromatics in high atom economy at ambient temperature by applying a photosensitizer, Acr+-Mes ClO4-, and a new cobalt catalyst, Co(dmgH)2(4-CONMe2Py)Cl is reported. Mechanistic investigations indicated
intermolecular coupling between internal alkynes and aromatic N-H ketimines. This novel alkyne hydroimination process is promoted by a catalyst system of a Ni(0) precursor ([Ni(cod)2]), N-heterocyclic carbene (NHC) ligand (IPr), and Cs2CO3 additive. The exclusive formation of (Z)-enamine stereoisomers is consistent with a proposed anti-iminometalation of alkyne by π-complexation with Ni(0) and subsequent