80542-40-1Relevant articles and documents
Nickel Catalyzed Imine Aldol Reactions between Activated Imines and Pronucleophiles
Shida, Naomi,Kubota, Yasufumi,Fukui, Hiroyuki,Asao, Naoki,Kadota, Isao,Yamamoto, Yoshinori
, p. 5023 - 5026 (1995)
Treatment of activated imines 1 with carbonyl compounds 2 in the presence of catalytic amounts of NiCl2(PPh3)2 or NiBr2(PPh3)2 at room temperature affords imine aldol products 3 in high to good yields.
A new tool to guide halofunctionalization reactions: The halenium affinity (HalA) scale
Ashtekar, Kumar Dilip,Marzijarani, Nastaran Salehi,Jaganathan, Arvind,Holmes, Daniel,Jackson, James E.,Borhan, Babak
, p. 13355 - 13362 (2014)
We introduce a previously unexplored parameter - halenium affinity (HalA)- as a quantitative descriptor of the bond strengths of various functional groups to halenium ions. The HalA scale ranks potential halenium ion acceptors based on their ability to stabilize a "free halenium ion". Alkenes in particular but other Lewis bases as well, such as amines, amides, carbonyls, and ether oxygen atoms, etc., have been classified on the HalA scale. This indirect approach enables a rapid and straightforward prediction of chemoselectivity for systems involved in halofunctionalization reactions that have multiple nucleophilic sites. The influences of subtle electronic and steric variations, as well as the less predictable anchimeric and stereoelectronic effects, are intrinsically accounted for by HalA computations, providing quantitative assessments beyond simple "chemical intuition". This combined theoretical-experimental approach offers an expeditious means of predicting and identifying unprecedented reactions.
Synthesis of β-Phosphinolactams from Phosphenes and Imines
Fu, Xingyang,Li, Xinyao,Xu, Jiaxi
supporting information, p. 8733 - 8737 (2021/11/17)
Various cis-β-phosphinolactams are synthesized stereoselectively for the first time from imines and diazo(aryl)methyl(diaryl)phosphine oxides under microwave irradiation. Diazo(aryl)methyl(diaryl)phosphine oxides first undergo the Wolf rearrangement to generate phosphenes. Imines nucleophilically attack the phosphenes followed by an intramolecular nucleophilic addition via less steric transition states to give final cis-β-phosphinolactams. C-Styrylimines generally give rise to β-phosphinolactams in higher yields than C-arylimines. The stereoselectivity and proposed mechanism are rationalized by DFT theoretical calculation.
Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
Wu, Jiajun,Darcel, Christophe
, p. 1023 - 1036 (2021/01/09)
A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.
Stereoselective Construction of γ-Lactams via Copper-Catalyzed Borylacylation
Bajohr, Jonathan,Lautens, Mark,Polishchuk, Iuliia,Torelli, Alexa,Whyte, Andrew
supporting information, p. 7915 - 7919 (2020/11/02)
A versatile and highly stereoselective borylative cyclization to generate polyfunctionalized γ-lactams has been developed. The stereoselective synthesis of these key ring systems is crucial due to their ubiquity in natural products. We report the diastero- and enantioselective construction of di- and trisubstituted γ-lactam cores, with examples containing an enantioenriched quaternary carbon.
Synthesis, characterization, molecular structure and computational study of tetrahedral pentamethylcyclopentadienyl iridacycle complexes with α,β-conjugated Schiff base ligands
Daud, Adibah Izzati,Khairul, Wan M.,Liu, Zhi-Qiang,Ong, Kok Tong,Tay, Meng Guan
, (2020/09/16)
Due to the excellent catalytic activities and phosphorescent properties that iridium complexes display, iridium chemistry has been of great interest for scientific investigation over the past 30 years. Iridium metallacycle analogues (also known as an iridacycles) bearing phenylpyridine (ppy) ligands have been well reported on, whilst complexes with R-phenyl-(3-R-phenylallylidene)amine, which is an α,β-conjugated Schiff base ligand, have not had the same attention, despite the fact that both ligands share a similar coordination mode. In this research, four pentamethylcyclopentadienyl iridacycle complexes, Ir1a-Ir1d, with different α,β-conjugated Schiff base ligands were synthesized from a di-μ-chloro-dichloro-bis-(η5-pentamethylcyclopentadienyl)diiridium(III) precursor. The iridacycle complexes were characterized using spectroscopic techniques and the molecular structures of Ir1ab-Ir1d were determined using X-ray crystallography. The X-ray results revealed that the iridacycle complexes have a tetrahedral geometry, the iridium centre being coordinated through the N[dbnd]C[sbnd]Cα[dbnd]Cβ moiety of the α,β-conjugated Schiff base ligand. Computational calculations with the B3LYP method and with LanL2DZ basis sets indicated that the HOMO-LUMO energy gaps Ir1b-Ir1d were in the range 3.31–3.36 eV. The OMe substituent at the C terminal has a greater impact on the HOMO energy level than the one at the N terminal.
Promoting Frustrated Lewis Pairs for Heterogeneous Chemoselective Hydrogenation via the Tailored Pore Environment within Metal–Organic Frameworks
Niu, Zheng,Zhang, Weijie,Lan, Pui Ching,Aguila, Briana,Ma, Shengqian
supporting information, p. 7420 - 7424 (2019/04/27)
Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal-free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β-unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β-unsaturated imine substrates to afford unsaturated amine compounds.
Development of Chiral Spiro Phosphoramidites for Rhodium-Catalyzed Enantioselective Reactions
Zheng, Zhiyao,Cao, Yuxi,Zhu, Dongsheng,Wang, Zheng,Ding, Kuiling
supporting information, p. 9491 - 9497 (2019/04/08)
A series of 1,1′-spirobiindane-7,7′-diol (SPINOL) analogues bearing a 2,2′-dimethyl-, cyclopentyl-, or cyclohexyl-fused ring were synthesized, and their distinct structural features were elucidated by X-ray crystallography. On the basis of these scaffolds, chiral monophosphoramidite ligands 6 a–m were synthesized, which demonstrated excellent enantioselectivity in RhI-catalyzed asymmetric hydrogenation of a dehydro amino acid methyl ester. Ligands 6 a–m were also successfully applied in the RhI-catalyzed enantioselective [4+2] cycloaddition of α,β-unsaturated imines with isocyanates, which afforded the corresponding pyrimidinones in good yields (60–92 %) with high enantioselectivities (75–92 % ee).
Heterogeneous Catalysis with Basic Compounds to Achieve the Synthesis and C-N Cleavage of Azetidin-2-ones under Microwave Irradiation
Alcaraz, Yolanda,Cruz, Francisco,De La Cruz, Fabiola N.,Delgado, Francisco,Domínguez, José Manuel,Galván, Adriana,Gomez, Clarisa Villegas,Martínez, Merced,Vázquez, Miguel A.
supporting information, p. 3625 - 3637 (2019/09/30)
The synthesis of azetidin-2-ones with a completely heterogeneous catalysis is reported. The use of basic compounds as solid catalysts allowed for the synthesis of azetidin-2-ones under microwave irradiation without organic additives such as triethylamine. An excellent catalyst for this transformation was Mg-Al hydroxide (MAH). The present methodology offers the advantages of non-hazardous reaction conditions, short reaction times, high yields, and catalyst reusability. Different substitution groups were tested on the imines and acyl chlorides to explore the scope of the reaction. Unconventional N-C4 bond cleavage was detected in azetidin-2-ones. MAH was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM).
Silylative Reductive Amination of α,β-Unsaturated Aldehydes: A Convenient Synthetic Route to β-Silylated Secondary Amines
Kim, Eunae,Park, Sehoon,Chang, Sukbok
, p. 5765 - 5769 (2018/03/28)
Described here is a reductive amination/hydrosilylation cascade of α,β-unsaturated aldehydes mediated by a Lewis acidic borane catalyst. The present reaction system provides an one-pot synthetic route towards β-silylated secondary amines that have not been accessible by other previous catalysis. Comparative 1H NMR studies on the silylative reduction of enimines revealed that steric bulkiness of primary amine reactants strongly affects both catalytic efficiency and regioselectivity. This strategy was applicable to a broad range of substrates and amenable to one-pot gram-scale synthesis. Moreover, a diastereoselective introduction of the β-silyl group was also found to be feasible (d.r. up to 71:29).
