Phân tích phổ NMR của các hợp chất 4-Azido-2-Metylquinolin thế

Các 4-azido-2-metylquinolin thế khác nhau đã được tổng hợp bằng phản ứng của dẫn xuất 4-cloro-2-metylquinolin thế tương ứng. Phổ 1H và 13C NMR của các hợp chất azide đã ghi và được thảo luận. Các tín hiệu cộng hưởng từ trong phổ NMR của chúng chỉ ra mối quan hệ giữa cấu trúc và vị trí của nhóm thế. Các kiểu ghépcặp spin-spin đã phản ánh các kiểu thế khác nhau ở vòng benzen của quinolin.
Nội dung trích xuất từ tài liệu:
Phân tích phổ NMR của các hợp chất 4-Azido-2-Metylquinolin thếTạp chí phân tích Hóa, Lý và Sinh học – Tập 22, Số 4/2017ANALYSIS OF NMR SPECTRA OF SUBSTITUTED4-AZIDO-2-METYLQUINOLINESĐến tòa soạn 25 - 5 - 2017Le The DuanHigh School for Gifted Students, VNU University of ScienceNguyen Dinh Thanh, Tran Thi Thanh VanFaculty of Chemistry, VNU University of ScienceTÓM TẮTPHÂN TÍCH PHỔ NMR CỦA CÁC HỢP CHẤT4-AZIDO-2-METYLQUINOLIN THẾCác 4-azido-2-metylquinolin thế khác nhau đã được tổng hợp bằng phản ứng củadẫn xuất 4-cloro-2-metylquinolin thế tương ứng. Phổ 1H và 13C NMR của các hợpchất azide đã ghi và được thảo luận. Các tín hiệu cộng hưởng từ trong phổ NMRcủa chúng chỉ ra mối quan hệ giữa cấu trúc và vị trí của nhóm thế. Các kiểu ghépcặp spin-spin đã phản ánh các kiểu thế khác nhau ở vòng benzen của quinolin.Keyword(s): 4-azido-2-metylquinoline, 4-cloro-2-metylquinoline.1. INTRODUCTIONThe compounds containing azidogroup have particular importance inorganic synthesis, and itself havebiological activity. The azidoderivatives are one of two importantprecursors in the synthesis ofheterocylic aromatic ring 1,2,3triazole through click reaction withalk-1-ynes [1-6].The synthetic method of substituted4-azido-2-metylquinolines 3a-j hasbeen reported previously [7]. In thisarticle, we announced that those 4azido derivatives were synthesized byreaction of corresponding 4-chloroones with sodium azide in DMF assolvent. There are several discussionsherein about the influence ofstructural factors to the positions ofresonance signals in their 1H and 13CNMR spectra of these azidoderivatives.II. EXPERIMENTAL PARTSubstituted 4-azido 3a-j (Scheme 1)were synthesized in bellow procedure[7] from 2-metylquinolin-4-ones 1a-j,respectively, through corresponding4-chloroquinoline derivatives [8].Their 1H and 13C NMR spectra was181recorded on FT-NMR Avance AV500Spectrometer (Bruker, Germany) at500.13 MHz and 125.77 MHz,respectively, using DMSO-d6 assolvent and TMS as an internalstandard. Spectral data of 1H and 13CNMR were summarized in Tables 1and 2.General procedure for synthesis ofsubstituted 4-azido-2-metylquinolines3a-j:To the solution of appropriatesubstituted 4-chloro-2-metylquinoline2a-j (10 mmol) in DMF (20 mL) in100 ml round-bottomed flask wasadded sodium azide (15 mmol). Afew crystals of KI then were added ascatalyst. The obtained mixture wasrefluxed with stirring on water-bath at50°C for 20 hours. Solvent DMF wasremoved completely in vacuum toobtained brown solids. Water wasadded to dissolve inorganic salts.Separated solid substance was filteredon Büchner funnel, washed well withwater, and dried in air. Thecompoundswerepurifiedbyrecrystallization from ethanol: toluene(9: 1) obtained crystals or solids. Theyields of products 3a-j were 78–97%.III. RESULTS AND DISCUSSIONThe selected 1H and 13C NMRspectral data of substituted 4-azido-2metylquinolines 3a-j were listed inTable 1 and 2. From Tables 1 and 2it’s shown that protons and carbon-13atoms in these molecules have properresonance signals in correspondingspectralregionswhicharecharacteristic for each type of atoms.Scheme 1: Synthesis path for substituted 4-azido-2-metylquinolines. Reactionconditions: (i) POCl3, 70°C until dissolved, then 90°C, 1 hr; (ii) NaN3, DMF,50°C, 20 hrs.The signal was located in region atinitialquinolin-4-ones1a-j11δ=10 61−10 36 ppm in H NMRdisappeared in H NMR spectra of thespectra that belonged to NH bond incorresponding azido derivatives 3a-j.182Simultaneously, in 13C NMR spectra,the chemical shift of the metyl groupon position 2 of azido derivatives 3a-jwas shifted downfield more than thatin corresponding 4(1H)-quinoline-4one derivatives 1a-j respectively, fromδ=20 3−15 6 ppm of 1a-j) [8] toδ=25 7−24 5 ppm of 3a-j, Table 2).The reason of these changes is that theanisotropicinfluenceofheteroaromatic ring (pyridine ring)was more powerful than double bondof alkene in quinoline-4-ones 1a-j thatwas non-heteroaromatic ring [8].Proton H-3 of the pyridine moiety incompounds 3a-j had resonance signalat δ=7 47−6 90 in singlet because thisproton had not magnetic interactionswith any other protons in quinolinering. In compared with compounds 1aj, it is found that the correspondingsignal of proton H-3 was located inupfield region δ=5 95−5 81 ppm, insinglet, Table 1). This eventdemonstrated that aromatic pyridinemoiety in compounds 3a-j alsoaffected to position of resonancesignal of proton H-3 and made it toshift to downfield region by theanisotropiceffectofthisheteroaromatic ring.Chemical shifts of both carbon atomsC-2 and C-8a were most affected byelectronegative nitrogen atom in ringquinoline; these resonance signalslocated in range of δ = 159 6−157 2ppm and δ=149 3−144 6 ppm,respectively(Table2).Metylsubstituent on position 2 of quinolinering had chemical shift in regi ...