Metal-Free Functionalization of Azine N-Oxides with Electrophilic Reagents

Baykov, Sergey V.; Boyarskiy, Vadim P.

doi:10.1007/s10593-020-02737-x

Cited by 14 publications

(7 citation statements)

References 55 publications

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“…Now a convenient method for the synthesis of N,Ndialkyl-N'-pyridin-2-yl-substituted ureas as a result of one-step activation of the CÀ H bond in pyridine-Noxides has been developed in our research group. [70][71][72][73] In further study, we demonstrated that these pyridylureas can be converted to N-pyridylcarbamates via heating with an excess of corresponding alcohols [74] (Scheme 1). According to our study, this process occurred via isocyanate intermediate formation and it motivated us to extend this reaction to N-nucleophiles.…”

Section: Introductionmentioning

confidence: 96%

“…Now a convenient method for the synthesis of N , N ‐dialkyl‐ N‘ ‐pyridin‐2‐yl‐substituted ureas as a result of one‐step activation of the C−H bond in pyridine‐ N ‐oxides has been developed in our research group [70–73] . In further study, we demonstrated that these pyridylureas can be converted to N ‐pyridylcarbamates via heating with an excess of corresponding alcohols [74] (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

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“Urea to Urea” Approach: Access to Unsymmetrical Ureas Bearing Pyridyl Substituents

et al. 2022

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A protocol for the synthesis of unsymmetrical ureas substituted by pyridyl/quinolinyl moiety has been developed. This method concluded in metal‐ and base‐free reamination of N,N‐dimethyl‐N‘‐hetaryl ureas with a wide range of aryl and alkyl amines. The isolated yields vary from 40 to 96% depending on the nucleophilicity of the amines. The scope of this method includes more than 50 examples. The reaction is not hindered by either donor or acceptor groups as well as diverse functionalities. The synthesis can be easily scaled to gram quantities. Theoretical calculations supported by experimental data allowed us to propose a plausible mechanism for the process. This reaction takes place through the intermediate formation of hetaryl isocyanate.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

“Urea to Urea” Approach: Access to Unsymmetrical Ureas Bearing Pyridyl Substituents

et al. 2022

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“…This disappointing void is primarily related to the low synthetic availability of 2-pyridyl ureas and the need to utilize toxic reagents in their preparation process [ 27 , 28 , 29 , 30 , 31 ]. To address this latter problem, we recently came up with a simple protocol for the preparation of diverse N , N -dialkyl- N ′-(pyridin-2-yl)-ureas via acid-catalyzed reaction of pyridine- N -oxides with dialkylcyanamides [ 32 , 33 , 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure, and Antiproliferative Action of 2-Pyridyl Urea-Based Cu(II) Complexes

et al. 2022

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Relying on a recently suggested protocol that furnishes convenient access to variously substituted 2-pyridyl ureas, twelve hitherto unknown Cu(II) complexes have been synthesized in the present work and their structures were evaluated by elemental analysis, HRMS, IR spectroscopy, and X-ray diffraction study. Two structural motifs ([Cu(L)2Cl]+[Cl]− or (Cu(L)2Cl2) depending on the substitution pattern on the 2-pyridine fragment were revealed. In addition, antiproliferative action of the obtained compounds have been investigated against lung cancer cell lines (A549, NCI-H460, NCI-H1975), and healthy WI-26 VA4 cells were used to monitor non-specific cytotoxicity. Two nitro-group substituted complexes Cu(U3)2Cl2 (IC50 = 39.6 ± 4.5 μM) and Cu(U11)2Cl2 (IC50 = 33.4 ± 3.8 μM) demonstrate enhanced activity against the drug resistant NCI-H1975 cells with moderate selectivity toward normal WI-26 VA4 cells. The antiproliferative mechanism of cell death underlying the growth inhibitory effect of the synthesized complexes was studied via additional experiments, including the cell cycle analysis and the apoptosis induction test. Reassuringly, certain 2-pyridyl urea-based Cu(II) complexes exerted cell line-specific antiproliferative effect which renders them valuable starting points for further unveiling the anticancer potential of this class of coordination compounds.

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“…While preparing and submitting this review, two reviews related to this topic have been published [25a–b] . An attempt has been made to compile majority of the available data to till date on the developments relating to α −C−H functionalization of six membered N ‐heteroaromatics under transition metal free conditions.…”

Section: Introductionmentioning

confidence: 99%

Transition Metal Free α−C−H Functionalization of Six Membered Heteroaromatic‐N‐Oxides

et al. 2021

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A comprehensive account of transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-N-oxides has been discussed in this review article. This review includes brief account of explanatory text with schemes, effect of substituents on the reaction and limitation of reaction for transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-N-oxides. Schemes depict the reaction conditions along with a quick look into their mechanism. Each of the reported example has been considered for reacting substrates such as readily available different six membered heteroaromatic-N-oxides, activating reagents, reaction conditions and different types of nucleophiles (N, Halogens, P, S, C and O), reaction conditions and reagents used for transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-Noxides. This review will be supportive to the chemists in understanding the challenges associated with the reported methods as well as the future potentials, both in the choice of substrates and reagents.

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Metal-Free Functionalization of Azine N-Oxides with Electrophilic Reagents

Cited by 14 publications

References 55 publications

“Urea to Urea” Approach: Access to Unsymmetrical Ureas Bearing Pyridyl Substituents

“Urea to Urea” Approach: Access to Unsymmetrical Ureas Bearing Pyridyl Substituents

Synthesis, Structure, and Antiproliferative Action of 2-Pyridyl Urea-Based Cu(II) Complexes

Transition Metal Free α−C−H Functionalization of Six Membered Heteroaromatic‐N‐Oxides

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