新型 N-酰基腙的合成及其 CN/NN 键构象的 NMR 光谱表征,Molecules

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新型 N-酰基腙的合成及其 CN/NN 键构象的 NMR 光谱表征
Molecules ( IF 4.2 ) Pub Date : 2021-08-13 , DOI: 10.3390/molecules26164908
Rubina Munir _{1,

2} , Noman Javid ₃ , Muhammad Zia-Ur-Rehman ₄ , Muhammad Zaheer ₄ , Rahila Huma ₂ , Ayesha Roohi ₂ , Muhammad Makshoof Athar ₁

Affiliation

在本文中，N '-(亚苄基)-2-(6-methyl- 1H - pyrazolo[3,4- b ]quinolin-1-yl)acetohydrazides 的合成及其通过 NMR 实验的结构解释在试图解释其¹ H- 和¹³ C-NMR 光谱中某些峰的重复。20 个新的 6-methyl-1 H - pyrazolo [3,4- b ]quinoline 取代的N-酰基腙6 ( a – t ) 是由 2-chloro-6-methylquinoline-3-carbaldehyde ( 1 ) 分四步合成的。2-Chloro-6-methylquinoline-3-carbaldehyde (1) 得到 6-methyl-1 H-吡唑并[3,4- b ]喹啉( 2 )，其在N-烷基化时产生2-(6-甲基-1H-吡唑并[3,4- b ]喹啉-1-基)乙酸酯( 3 )。3 的肼解，然后将得到的 2-(6-methyl-1 H - pyrazolo[3,4- b ]quinolin-1-yl)acetohydrazide ( 4 ) 与芳香醛缩合得到N-酰基腙6 ( a – t）。合成化合物的结构是通过容易获得的技术确定的，例如 FT-IR、NMR 和质谱研究。的立体化学行为6（a – t ) 在二甲基亚砜-d ₆溶剂中通过¹ H NMR 和¹³ C NMR 技术在室温下进行研究。核磁共振谱显示存在N '-(亚苄基)-2-(6-甲基-1 H-吡唑并[3,4- b ]喹啉-1-基)乙酰肼，作为两种构象异构体的混合物，即E _{(C =N)(NN) 共} 面和E _(C=N)(NN)在室温下在 DMSO- d _{6 中}反面。还计算了两种构象异构体的比率，并且E _{(C=N) (NN)}同周平面构象异构体被确定为与E _{(C = N) (NN)}反周平面形式的平衡百分比更高。

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Synthesis of Novel N-Acylhydrazones and Their C-N/N-N Bond Conformational Characterization by NMR Spectroscopy

In this article, a synthesis of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides and their structural interpretation by NMR experiments is described in an attempt to explain the duplication of some peaks in their ¹H- and ¹³C-NMR spectra. Twenty new 6-methyl-1H-pyrazolo[3,4-b]quinoline substituted N-acylhydrazones 6(a–t) were synthesized from 2-chloro-6-methylquinoline-3-carbaldehyde (1) in four steps. 2-Chloro-6-methylquinoline-3-carbaldehyde (1) afforded 6-methyl-1H-pyrazolo[3,4-b]quinoline (2), which upon N-alkylation yielded 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetate (3). The hydrazinolysis of 3 followed by the condensation of resulting 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazide (4) with aromatic aldehydes gave N-acylhydrazones 6(a–t). Structures of the synthesized compounds were established by readily available techniques such as FT-IR, NMR and mass spectral studies. The stereochemical behavior of 6(a–t) was studied in dimethyl sulfoxide-d₆ solvent by means of ¹H NMR and ¹³C NMR techniques at room temperature. NMR spectra revealed the presence of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides as a mixture of two conformers, i.e., E_(C=N)(N-N) synperiplanar and E_(C=N)(N-N)antiperiplanar at room temperature in DMSO-d₆. The ratio of both conformers was also calculated and E_{(C=N) (N-N)} syn-periplanar conformer was established to be in higher percentage in equilibrium with the E_{(C=N) (N-N)}anti-periplanar form.

更新日期：2021-08-13

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