Tert-butyl 4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate (3.5 g, 16.7 mmol) was dissolved in tetrahydrofuran (35 ml), and sodium hydride (1.0 g, 60%, 25.4 mmol) was added at 0°C, followed by reaction for 30 min. Methylsulfonyl chloride (2.9 g, 25.4 mmol) was added, followed by a reaction for 1 hour. The reaction was quenched by the addition of water (10 ml) to the reaction solution, which was extracted with ethyl acetate (50 ml*2). The organic layers were combined, dried over anhydrous sodium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether/ethyl acetate (v/v) = 1:1), to obtain tert-butyl 2-(Methylsulfonyl)-4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate (2.1 g, yield 44%).
![tert-butyl 2-(Methylsulfonyl)-4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate](/NewsImg/2023-10-17/6383313814796791749926853.jpg "tert-butyl 2-(Methylsulfonyl)-4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate")
![tert-butyl 2-(Methylsulfonyl)-4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate](/NewsImg/2023-10-17/6383313930512510309750544.jpg "tert-butyl 2-(Methylsulfonyl)-4,6-dihydropyrrolo[3,4-c]pyrazole-5(2H)-carboxylate")