Structure Elucidation of cis- and trans-1,2,4-Oxadiazol Derivatives

doi:10.11938/cjmr20253184

Abstract

Abstract:

The geometric configuration of cis-trans isomers critically influences their biological activities, making the separation and configurational identification essential for efficacy evaluation. In this study, cis/trans-1,2,4-oxadiazole derivatives were synthesized and comprehensively characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), high-resolution mass spectrometry (HRMS), and theoretical calculations. This approach enabled unambiguous identification and distinction of a pair of isomers, including cis-4-[2-(3-((1H-indol-3-yl)methyl)-1,2,4-oxadiazol-5-yl)vinyl]-N,N-dimethylaniline and its trans-configuration analogue. Anti-Toxoplasma gondii activity assessment revealed that the cis-isomer (compound 2, selectivity index SI = 1.50) exhibited higher activity than the trans-isomer (compound 1, SI = 0.92) and the positive control spiramycin (SI = 0.98), highlighting the value of configurational separation and identification in pharmaceutical research. This study deepens the understanding of configuration-activity relationships and provides new insights for developing highly selective anti-Toxoplasma agents.

Key words: 1,2,4-oxadiazole, antiparasitic agents, structural elucidation, cis-configuration, NMR

CLC Number:

O482.53

GAO Yuan, LIU Xinyue, WANG Sihong, HU Wei. Structure Elucidation of cis- and trans-1,2,4-Oxadiazol Derivatives[J]. Chinese Journal of Magnetic Resonance, 2026, 43(2): 164-174.

Figures/Tables 8

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Table 1

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Position	δ_H（化合物1实验值）	δ_H（化合物1计算值）	δ_H（化合物2实验值）	δ_H（化合物2计算值）
1(NH)	8.08		8.07
2	7.21	7.24	7.21	7.04
4	7.36	7.41	7.37	7.19
5	7.20	7.06	7.15	6.62
6	7.64	7.58	7.20	6.98
7	7.13	6.58	7.76	7.77
10	4.24	4.09	4.26	4.22
13	6.71	6.58	6.17	5.77
14	7.68	7.75	6.88	6.49
16	7.43	7.50	7.79	8.02
17	6.57	6.45	6.57	6.42
19	3.03	3.11	3.02	3.14

Position	δ_C（化合物1实验值）	δ_C（化合物1计算值）	δ_C（化合物2实验值）	δ_C（化合物2计算值）
2	123.0	125.8	123.1	122.5
3	110.4	109.9	110.6	108.6
4	111.3	111.1	111.3	109.3
5	122.4	120.7	122.3	120.6
6	119.8	120.4	119.8	118.6
7	119.2	117.7	119.4	117.8
8	136.4	134.9	136.4	137.9
9	127.3	126.1	127.4	126.2
10	22.9	22.5	22.8	24.9
11	169.9	174.0	169.8	174.0
12	176.3	177.7	176.2	177.1
13	104.9	101.6	105.0	100.6
14	143.0	144.6	142.4	143.8
15	122.4	122.9	122.6	121.2
16	129.7	133.0	132.7	130.8
17	112.0	117.1	111.3	110.6
18	151.9	148.8	151.4	148.2
19	40.3	40.3	40.3	40.3