1750-36-3Relevant articles and documents
Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
, p. 3843 - 3853 (2021/11/18)
Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
Gold-Catalyzed Bicyclic and [3+2]-Annulations of Internal Propargyl Alcohols with Nitrones and Imines To Yield to Two Distinct Heterocycles
More, Sayaji Arjun,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
supporting information, p. 525 - 531 (2020/12/01)
A gold-catalyzed synthesis of 1,3-dihydrooxazolo[3,4-a]indoles from 1-oxo-3-yn-4-ols and nitrones is described; this new bicyclic annulation presents the first examples that internal alkynes can react with nitrones to undergo an oxoarylation route. DFT calculations indicate a [3,3]-sigmatropic shift of initial alkenylgold intermediates to elude the intermediacy of gold carbenes. We also developed new [3+2]-annulations of the same 1-oxo-3-yn-4-ols with imines, yielding oxazolidin-4-ylidene derivatives efficiently. The tethered alcohols of these 1-oxo-3-ynes allow trapping of their metastable 2-azadienium intermediates to enable a novel annulation. Our mechanistic analysis indicates that the two products, despite their structural relevance, are produced from two independent systems. (Figure presented.).
Synthesis of chromeno[3,4-b]piperazines by an enol-ugi/reduction/cyclization sequence
Bornadiego, Ana,Neo, Ana G.,Marcos, Carlos F.
supporting information, (2021/05/31)
Keto piperazines and aminocoumarins are privileged building blocks for the construction of geometrically constrained peptides and therefore valuable structures in drug discovery. Combining these two heterocycles provides unique rigid polycyclic peptidomimetics with drug-like properties including many points of diversity that could be modulated to interact with different biological receptors. This work describes an efficient multicomponent approach to condensed chromenopiperazines based on the novel enol-Ugi reaction. Importantly, this strategy involves the first reported post-condensation transformation of an enol-Ugi adduct.
