反应详情

温度

97.5 °C

Benzyl carbazate (25 g, 0.15 mol) was dissolved in 50 mL of DMF in a round bottom flask. The solution was heated to 95-100° C. From two separate addition funnels, ethyl 2-bromoisobutyrate (58.5 g, 0.3 mol) and pyridine (29.7 g, 0.375 mol, 30 mL) were added drop-wise separately and simultaneously over 30-120 minutes. Heating was continued if necessary to propel the reaction to completion. The reaction was monitored by TLC (30% ethyl acetate in hexanes, I2 visualization). The mixture was allowed to cool, and then poured onto ice water. The aqueous mixture was extracted with ethyl ether, and the solvent was removed in vacuo. 2-(N′-benzyloxycarbonyl-hydrazino)-2-methyl-propionic acid ethyl ester was isolated, optionally after silica gel chromatography. 1H NMR (300 MHz, CDCl3) δ (ppm): 7.36 (br s, 5H), 6.6 (br s, 1H), 5.15 (br s, 2H), 4.2 (q, 2H), 1.3 (s, 6H), 1.25 (t, 3H). 1H NMR analysis alone is insufficient to ascertain the extent of the reaction.

1. customFrom two separate
2. additionaddition funnels
3. temperatureHeating
4. customthe reaction to completion
5. temperatureto cool
6. additionpoured onto ice water
7. extractionThe aqueous mixture was extracted with ethyl ether
8. customthe solvent was removed in vacuo