Synthesis
The general procedure for the synthesis of 5-(4-nitrophenyl)-1H-tetrazole from 4-nitrophenyl aldoxime was as follows: InCl3 (3 mol%) was added to a stirred solution of DMF (5 mL) containing appropriate amounts of aldoxime (1 mmol) and NaN3 (1.5 mmol). The reaction mixture was heated to 120 °C. After completion of the reaction (monitored by TLC), the mixture was cooled to room temperature. H2O (5 mL), 2M HCl aqueous solution (10 mL) and EtOAc (10 mL) were added sequentially with vigorous stirring for 15 minutes. The organic layer was separated and the aqueous layer was extracted with EtOAc (3 x 15 mL). The organic extracts were combined, washed with H2O, dried over anhydrous Na2SO4 and filtered. The solvent was evaporated under reduced pressure and the crude product was purified by silica gel column chromatography [eluent: EtOAc-hexane (9:1)].
References
[1] Synlett, 2016, vol. 27, # 8, p. 1241 - 1244
[2] Tetrahedron Letters, 2012, vol. 53, # 29, p. 3706 - 3709
[3] Synthesis (Germany), 2018, vol. 50, # 6, p. 1293 - 1300
[4] Synlett, 2016, vol. 27, # 15, p. 2225 - 2228
[5] Tetrahedron Letters, 2016, vol. 57, # 5, p. 523 - 524
