反应详情

To a solution of tert-butyl hydrazinecarboxylate 1 (CAS Reg. No. 870-46-2) (25.1 g, 0.190 mol) in acetone (185 mL) was added the magnesium sulfate (6 g) and 12 drops acetic acid (Wu et al (2012) Jour. Med. Chem. 55(6):2724-2736; WO 2007/056170; Zawadzki et al (2003) Polish Jour. Chem. 77(3):315-319). The mixture was heated to reflux for 2.5 h and cooled to rt and filtered. The filtrate was concentrated to give tert-butyl 2-(propan-2-ylidene)hydrazinecarboxylate 2 (CAS Reg. No. 16689-34-2) as an off-white solid (32 g, 98%) (used in the next step without further purification). LC-MS [M+H]+=172.9, RT=2.11 min. 1H NMR 300 MHz (CDCl3) d 7.35 (br s, 1H, NH), 2.04 (s, 3H), 1.82 (s, 3H), 1.54 (s, 9H); 13C NMR 300 MHz (CDCl3) d 152.9, 149.7, 80.7, 28.1, 25.3, 15.9.

1. temperatureThe mixture was heated
2. temperatureto reflux for 2.5 h
3. filtrationfiltered
4. concentrationThe filtrate was concentrated