Ethyl bromoacetate → Tert-butyl 2-(2-ethoxy-2-oxoethyl)hydrazine-1-carboxylate

Temperature

100 °C

A 500 mL 3-neck round bottom flask was charged with t-butyl carbazate (15.0 g, 113.5 mmol), toluene (120 mL), triethylamine (18.98 mL, 136.2 mmol) and ethyl bromoacetate (15.10 mL, 136.2 mmol). The mixture was heated in an oil bath to about 100° C. for 19 hours. The reaction mixture was allowed to cool to room temperature and was then filtered, washing the solid triethylamine bromide with ethyl acetate/hexanes. The combined organics were washed successively with saturated sodium bicarbonate, water and brine, dried over sodium sulfate, filtered, concentrated and dried in vacuo to give a crude reddish oil (20.78 g). The crude material was absorbed onto Celite® and purified on a 10×20 cm silica gel column eluting with 15% (4 L), 20% (7 L), 30% (2 L), 40% (2 L), 50% (2 L) ethyl acetate/hexanes and finally ethyl acetate (2 L). The desired fractions were combined and concentrated to give an oil (10.85 g) which solidified upon standing. The residue was concentrated with dichloro-methane/toluene and dried in vacuo to give compound A (44%) as an off-white solid. TLC: Rf =0.13, silica gel, 30% ethyl acetate/hexanes, UV and PMA detection.

1. temperatureto cool to room temperature
2. filtrationwas then filtered
3. washwashing the solid triethylamine bromide with ethyl acetate/hexanes
4. washThe combined organics were washed successively with saturated sodium bicarbonate, water and brine
5. dry with materialdried over sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated
8. customdried in vacuo
9. customto give a crude reddish oil (20.78 g)
10. customThe crude material was absorbed onto Celite®
11. custompurified on a 10×20 cm silica gel column
12. washeluting with 15% (4 L), 20% (7 L), 30% (2 L), 40% (2 L), 50% (2 L) ethyl acetate/hexanes and finally ethyl acetate (2 L)
13. concentrationconcentrated

ORD record

ord-b38b30e769ac41239540c0827db9a13c

Source dataset

uspto-grants-1997_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05635504