(1H-Benzo[d]imidazol-2-yl)methanamine

Synthesis

GENERAL METHOD: O-phenylenediamine (0.54 g, 5 mmol) and glycine (0.53 g, 7 mmol) were sequentially added to a rapid flask containing 10 mL of toluene. The reaction mixture was heated and refluxed under magnetic stirring at 85-95 °C for 9 h. A colored solution was generated during the reaction. Upon completion of the reaction, the mixture was cooled to room temperature and allowed to stand overnight. The precipitated crystals were filtered and dried in air to give (1H-benzo[d]imidazol-2-yl)methylamine (10a) in 97.3% yield. In view of the high efficiency demonstrated by method B in the synthesis of 10a, the method was employed to synthesize the remaining compounds (10b-i). The NMR hydrogen spectrum (400 MHz, DMSO-d6) δ of the product 10a: 7.95 (s, 1H, NH), 7.82-7.80 (d, J = 8.03 Hz, 2H, Ar-H), 7.17-7.13 (m, 2H, Ar-H), 6.44-6.42 (t, J = 5.78 Hz, 2H, NH2-CH2). 3.55-3.53 (t, J = 5.78 Hz, 2H, CH2-NH2). NMR carbon spectrum (100 MHz, DMSO-d6) δ: 142.6, 139.3, 138.9, 125.3, 125.3, 119.2, 119.2, 41.7 ppm. uv-vis spectra (λmax, nm) (logεmax): 236 (1.7782), 290 (1.324), 407 ( 0.8541). IR spectra (KBr, cm-1): 3384, 3363 (NH of NH2, double peak), 3245 (NH), 3021 (aromatic CH), 2930 (aliphatic CH), 1605 (C=C), 1580 (C=N), 741 (Ar-H). Mass spectra (m/z, relative %): 295.04 (2M+1, 1.5%), 148.01 (MH, 24.5%), 147.03 (M+, 20%), 132.04 (M-NH, 100%), 118.07 (M-CH2=NH, 35.3%), 76.11 (68.3%).

References

[1] Oriental Journal of Chemistry, 2016, vol. 32, # 1, p. 109 - 120
[2] Molecules, 2015, vol. 20, # 8, p. 15206 - 15223
[3] Journal of the Korean Chemical Society, 2014, vol. 58, # 5, p. 450 - 455
[4] Asian Journal of Chemistry, 2014, vol. 26, # 3, p. 926 - 932
[5] Bioorganic and Medicinal Chemistry, 2014, vol. 22, # 1, p. 550 - 558