N'-benzyl-2,2-dimethylpropanehydrazide

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of ethyl thiooxamate (0.27 g, 2.0 mmol) and triethyloxonium tetrafluoroborate (0.40 g, 2.1 mmol) in CH2Cl2 (25 mL) was stirred at room temperature 2 h. The reaction was cooled in an ice bath, and a solution of N′-benzylpivalohydrazide (0.41 g, 2.0 mmol) and triethylamine (0.28 mL, 2.0 mmol) in CH2Cl2 (10 mL) was slowly added. The cooling bath was removed, and the reaction was heated to reflux for 90 min. The solvent was removed under vacuum, and the residue was purified by silica gel chromatography (0%-25% EtOAc-hexanes) to obtain ethyl 5-tert-butyl-2-benzyl-2H-1,2,4-triazole-3-carboxylate (0.23 g, 40% yield). 1H NMR (400 MHz, CDCl3) δ 7.34-7.28 (m, 5H), 5.73 (s, 2H), 4.43 (q, J=7.1 Hz, 2H), 1.40 (s, 9H), 1.38 (t, J=7.7 Hz, 3H) ppm. LC/MS: m/z 288.2 (M+H)+ at 3.51 min (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)). The reaction was cooled in an ice bath The cooling bath was removed the reaction was heated to reflux for 90 min The solvent was removed under vacuum the residue was purified by silica gel chromatography (0%-25% EtOAc-hexanes)