A solution of 3-tert-butyldimethylsiloxymethyl-1H-1,2,4-triazole (8.0 g) in N,N-dimethylformamide (20 ml) was added dropwise at 0° C. to a mixture of 60% sodium hydride in oil (1.5 g), methyl iodide (2.8 ml) and N,N-dimethylformamide (80 ml) for 10 minutes. The mixture was stirred for 10 minutes, to which was added water (300 ml), followed by extraction with ethyl acetate (100 ml×3 times). The organic layer was washed with a saturated aqueous sodium chloride solution, which was then dried over anhydrous sodium sulfate, followed by concentration under reduced pressure. The concentrate was subjected to a silica gel chromatography, eluting with ethyl acetate-hexane (1:1), then further with ethyl acetate. The object fractions were respectively concentrated under reduced pressure to afford 5-tert-butyldimethylsiloxymethyl-1-methyl-1H-1,2,4-triazole (4.4 g), 3-tert-butyldimethylsiloxymethyl-1-methyl-1H-1,2,4-triazole (2.4 g), and 3-tert-butyldimethylsiloxymethyl-4-methyl-4H-1,2,4-triazole (0.50 g).
