Acetic Acid → tert-Butyl 2-cyclobutylhydrazinecarboxylate

Temperature

25 °C

Cyclobutanone (8.19 g, 116.85 mmol) was dissolved in ethanol (60 mL). tert-Butyl carbazate (15.64 g, 118.34 mmol) was added. The reaction was stirred at 25° C. for 2.5 h before it was concentrated in vacuo. The residue was re-dissolved in ethanol (60 mL). Acetic acid (14.09 mL, 246.14 mmol) and sodium cyanoborohydride (15.46 g, 246.02 mmol) were added. The reaction was stirred at 25° C. for 48 h. The reaction was quenched via slow addition of saturated aqueous sodium bicarbonate solution (until pH 8 was reached). The resulting mixture was extracted with ethyl acetate (3×150 mL). The organic layers were combined, dried over magnesium sulfate, filtered and concentrated in vacuo to afford a yellow oil. Purification by flash column chromatography (Teledyne Isco RediSep Column; 0-30% ethyl acetate in hexanes) afforded the desired product, N′-cyclobutyl-hydrazinecarboxylic acid tert-butyl ester (5.42 g, 29.10 mmol, 25%), as a white powder. 1H NMR (400 MHz, CDCl3) δ: 1.48 (9H, s), 1.62-1.70 (1H, m), 1.73-1.82 (1H, m), 1.84-1.94 (2H, m), 2.07-2.15 (2H, m), 3.56-3.63 (1H, m).

1. concentrationwas concentrated in vacuo
2. dissolutionThe residue was re-dissolved in ethanol (60 mL)
3. stirringThe reaction was stirred at 25° C. for 48 h
4. customThe reaction was quenched via slow addition of saturated aqueous sodium bicarbonate solution (until pH 8 was reached)
5. extractionThe resulting mixture was extracted with ethyl acetate (3×150 mL)
6. dry with materialdried over magnesium sulfate
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customto afford a yellow oil
10. customPurification by flash column chromatography (Teledyne Isco RediSep Column; 0-30% ethyl acetate in hexanes)

ORD record

ord-6a6777506a244d44bcbd18a45da42f06

Source dataset

uspto-grants-2009_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07582626B2