- Synthesis of β-Phosphinolactams from Phosphenes and Imines
-
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.
- Fu, Xingyang,Li, Xinyao,Xu, Jiaxi
-
supporting information
p. 8733 - 8737
(2021/11/17)
-
- Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
-
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.
- Wu, Jiajun,Darcel, Christophe
-
p. 1023 - 1036
(2021/01/09)
-
- Synthesis, characterization, molecular structure and computational study of tetrahedral pentamethylcyclopentadienyl iridacycle complexes with α,β-conjugated Schiff base ligands
-
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.
- Daud, Adibah Izzati,Khairul, Wan M.,Liu, Zhi-Qiang,Ong, Kok Tong,Tay, Meng Guan
-
-
- Stereoselective Construction of γ-Lactams via Copper-Catalyzed Borylacylation
-
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.
- Bajohr, Jonathan,Lautens, Mark,Polishchuk, Iuliia,Torelli, Alexa,Whyte, Andrew
-
supporting information
p. 7915 - 7919
(2020/11/02)
-
- Promoting Frustrated Lewis Pairs for Heterogeneous Chemoselective Hydrogenation via the Tailored Pore Environment within Metal–Organic Frameworks
-
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.
- Niu, Zheng,Zhang, Weijie,Lan, Pui Ching,Aguila, Briana,Ma, Shengqian
-
supporting information
p. 7420 - 7424
(2019/04/27)
-
- Development of Chiral Spiro Phosphoramidites for Rhodium-Catalyzed Enantioselective Reactions
-
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).
- Zheng, Zhiyao,Cao, Yuxi,Zhu, Dongsheng,Wang, Zheng,Ding, Kuiling
-
supporting information
p. 9491 - 9497
(2019/04/08)
-
- Stereoselective synthesis, spectroscopic and X-ray crystallographic characterization of novel trans- and cis-3-methylseleno substituted monocyclic β-lactams: Potential synthons for C-3 functionalized/bicyclic/halospiroseleno-β-lactams of medicinal interes
-
New series of trans- and cis-3-methylseleno substituted β-lactams (4, 5) have been prepared from 2-methylselenoethanoic acid (2). The four-membered β-lactam ring was introduced by the condensation reaction between ketene retrieved from 2-methylselenoethan
- Bhalla, Aman,Nagpal, Yogesh,Berry, Shiwani,Narula, Dipika,Bari,Bhasin,Kumar, Rajeev
-
p. 172 - 182
(2018/03/24)
-
- Efficient Synthesis of Amines by Iron-Catalyzed C=N Transfer Hydrogenation and C=O Reductive Amination
-
Here we report the catalytic transfer hydrogenation (CTH) of non-activated imines promoted by a Fe-catalyst in the absence of Lewis acid co-catalysts. Use of the (cyclopentadienone)iron complex 1, which is much more active than the classical ‘Kn?lker complex’ 2, allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5–2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this methodology, we developed a one-pot CTH protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates. (Figure presented.).
- Facchini, Sofia Vailati,Cettolin, Mattia,Bai, Xishan,Casamassima, Giuseppe,Pignataro, Luca,Gennari, Cesare,Piarulli, Umberto
-
supporting information
p. 1054 - 1059
(2018/01/27)
-
- Synthesis, structure-activity relationships and preliminary mechanism study of N-benzylideneaniline derivatives as potential TLR2 inhibitors
-
Toll-like receptor 2 (TLR2) can recognize pathogen-associated molecular patterns to defense against invading organisms and has been represents an attractive therapeutic target. Until today, none TLR2 small molecule antagonist have been developed in clinic
- Cai, Shaoyi,Zhu, Gengzheng,Cen, Xiaohong,Bi, Jingjie,Zhang, Jingru,Tang, Xiaoshan,Chen, Kun,Cheng, Kui
-
p. 2041 - 2050
(2018/03/13)
-
- Silylative Reductive Amination of α,β-Unsaturated Aldehydes: A Convenient Synthetic Route to β-Silylated Secondary Amines
-
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).
- Kim, Eunae,Park, Sehoon,Chang, Sukbok
-
supporting information
p. 5765 - 5769
(2018/03/28)
-
- Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides
-
A modular substrate-controlled hexannulation of inherently promiscuous 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.
- Braunstein, Hannah,Langevin, Spencer,Khim, Monique,Adamson, Jonathan,Hovenkotter, Katie,Kotlarz, Lindsey,Mansker, Brandon,Beng, Timothy K.
-
supporting information
p. 8864 - 8872
(2016/10/03)
-
- Zn-Catalyzed Enantio- and Diastereoselective Formal [4 + 2] Cycloaddition Involving Two Electron-Deficient Partners: Asymmetric Synthesis of Piperidines from 1-Azadienes and Nitro-Alkenes
-
We report a catalytic asymmetric synthesis of piperidines through [4 + 2] cycloaddition of 1-azadienes and nitro-alkenes. The reaction uses earth abundant Zn as catalyst and is highly diastereo- and regioselective. A novel BOPA ligand (F-BOPA) confers high reactivity and enantioselectivity in the process. The presence of ortho substitution on the arenes adjacent to the bis(oxazolines) was found to be particularly impactful, due to limiting the undesired coordination of 1-azadiene to the Lewis acid and thus allowing the reaction to be carried out at lower temperature. A series of secondary kinetic isotope effect studies using a range of ligands implicates a stepwise mechanism for the transformation, involving an initial Michael-type addition of the imine to the nitro-alkene followed by a cyclization event. The stepwise mechanism obviates the electronic requirement inherent to a concerted mechanism, explaining the successful cycloaddition between two electron-deficient partners. (Chemical Equation Presented).
- Chu, John C. K.,Dalton, Derek M.,Rovis, Tomislav
-
supporting information
p. 4445 - 4452
(2015/04/14)
-
- An efficient three-component synthesis of homoallylic amines catalysed by MgI2 etherate
-
A three-component reaction of aldehydes, amines and allyltributylstannane was efficiently carried out to afford the corresponding homoallylic amine derivatives in the presence of 20 mol% of MgI2 etherate [(MgI 2?(OEt2)n] under mild and neutral reaction conditions in good to excellent yields.
- Wang, Yanping,Liu, Yingshuai,Hu, Shenghui,Zhang, Xingxian
-
experimental part
p. 21 - 24
(2012/03/27)
-
- One-pot sequence synthesis of azetidin-2-one using diethyl chlorophosphate
-
A simple and convenient synthesis of 2-azetidinone derivatives from the reaction of a pre-mixture of amines and aldehydes with carboxylic acids in the presence of diethyl chlorophosphate by [2+2] cycloaddition reaction is described. Separation and purification of imines as intermediates were not required. The methodology is convenient and good to excellent yields of products were obtained with simple purification.
- Zarei, Maaroof
-
experimental part
p. 118 - 120
(2012/05/04)
-
- GREEN SYNTHESIS OF ARYL ALDIMINES USING ETHYL LACTATE
-
The present invention relates to a method for preparing aryl aldimines. In particular, the present invention relates to methods of preparing aryl aldimines that uses environmentally friendly solvent systems.
- -
-
Page/Page column 4-5
(2011/08/22)
-
- Ethyl lactate as a tunable solvent for the synthesis of aryl aldimines
-
Ethyl L-lactate can be tuned with a cosolvent to create polarity conditions ideal for synthesizing aryl aldimines that crystallize directly out of solution within minutes under ambient conditions in excellent yields and requiring no further purification.
- Bennett, Jacqueline S.,Charles, Kaitlyn L.,Miner, Matthew R.,Heuberger, Caitlin F.,Spina, Elijah J.,Bartels, Michael F.,Foreman, Taylor
-
body text
p. 166 - 168
(2010/04/22)
-
- The Vilsmeier reagent: a useful and versatile reagent for the synthesis of 2-azetidinones
-
(Chloromethylene)dimethylammonium chloride (Vilsmeier reagent), prepared easily from N,N-dimethylformamide and oxalyl chloride or thionyl chloride, works as a versatile acid activator reagent for the direct [2+2] ketene-imine cycloaddition of substituted
- Jarrahpour, Aliasghar,Zarei, Maaroof
-
experimental part
p. 2927 - 2934
(2009/05/30)
-
- Staudinger/aza-Wittig reactions utilizing a novel linear polymer-supported triphenylphosphine as a modified liquid-phase reagent
-
A new triphenylphosphine reagent linked to a linear maleimide-styrene copolymer is synthesized and is found to be effective for the formation of a variety of imines via the Staudinger/aza-Wittig reaction. This linear polymer-supported triphenylphosphine h
- Mahdavi, Hossein,Amani, Javad
-
experimental part
p. 5923 - 5926
(2010/01/11)
-
- Anti-tumor compounds, pharmaceutical compositions, methods for preparation thereof and for treatment
-
The present invention is directed to novel taxanes useful as chemotherapeutic agents or their precursors. Processes for preparing the novel taxanes include coupling reactions, in the presence of a base, of baccatin of formula (III) or (IV) STR1 with β-lac
- -
-
-
- Stereoselectivity in the Condensation Reactions between Malate Enolate and Imines to 2-Pyrrolidinone Derivatives
-
Enolate dianion of diethyl (S)-malate was stereoselectively condensed with nonenolizable N-arylimines to give 2-pyrrolidinone derivatives.The presence of HMPA changes the diastereoselectivity of this cyclization reaction.
- Ha, Deok-Chan,Yun, Kyeong-Soon,Park, Hye-Sang,Choung, Won-Keun,Kwon, Young-Eun
-
p. 8445 - 8448
(2007/10/02)
-
- Anti-tumor compounds, pharmaceutical compositions, methods for preparation thereof and for treatment
-
The present invention is directed to novel taxanes useful as chemotherapeutic agents or their precursors. Processes for preparing the novel taxanes include coupling reactions, in the presence of a base, of baccatin of formula (III) or (IV) STR1 with β-lac
- -
-
-
- Process for the production of chiral hydroxy-β-lactams and hydroxyamino acids derived therefrom
-
The reaction between a hydroxyacetic acid derivative bearing an oxygen protecting group and a chiral auxiliary group and an imine produces chiral β-lactams. Hydrolysis of the chiral β-lactams produces chiral amino acid analogs.
- -
-
-
- The Reaction of α,β-Unsaturated Aldimines with Benzofuroxan
-
Benzofuroxan reacts with imines derived from crotonaldehyde and cinnamaldehyde, to form 2-iminomethylquinoxaline 1,4-dioxides.
- Devi, Purabi,Sandhu, Jagir S.
-
p. 427 - 428
(2007/10/02)
-
- Ruthenium-catalysed Oxidation of Secondary Amines to Imines using t-Butyl Hydroperoxide
-
The ruthenium-catalysed oxidation of secondary amines with t-butyl hydroperoxide under mild conditions affords the corresponding imines in high yields.
- Murahashi, Shun-Ichi,Naota, Takeshi,Taki, Hiroshi
-
p. 613 - 614
(2007/10/02)
-
- Synthesis of New Polycyclic Carbazoloquinones
-
Some new policyclic carbazoloquinones, substituted 6H-pyridocarbazoles (V) have been synthesized by the interaction of the Diels-Alder adducts (II), obtained from the addition of cinnamyliden-anils (I) to 4,4-dimethoxyquinone in 1:1 molar ratio, wi
- Hammam, A. S.,Youssef, M. S. K.,Abbady, M. A.,Ibrahim, R. R.
-
p. 565 - 570
(2007/10/02)
-