tert-Butyl 2-(2-acetylhydrazino)-2-oxoethylcarbamate

 tert-Butyl 2-(2-acetylhydrazino)-2-oxoethylcarbamate

2-Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (7.06 g, 28.5 mmol) was added to a solution of N-tert-butoxycarbonylglycine (5.0 g, 28.6 mmol) in dichloromethane (75 ml), and the solution stirred for 15 minutes. Acetic hydrazide (2.6 g, 35.1 mmol) was added, and the reaction stirred at room temperature for 18 hours. The resulting precipitate was filtered, and dried in vacuo, to afford a white crystalline solid, 2.42 g. The filtrate was concentrated under reduced pressure, diluted with ether, and the resulting precipitate filtered and dried in vacuo, to afford additional product as a white solid, 4.4 g, 67% in total; 

¹H NMR (CDCl₃, 400 MHz) δ: 1.41 (s, 9H), 2.02 (s, 3H), 3.87 (d, 2H), 5.22 (bs, 1H), 8.27 (bs, 1H), 8.84 (bs, 1H); LRMS: m/z 249.2 (MNH₄ ⁺);