Triethylamine → alpha-Azaglycinyl-(L)-proline t-butyl ester

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Reaction Steps

A solution of carbamoyl chloride 1 (1.00 g; from above) in dry THF (3.5 ml) was added over 10 minutes to an ice-cold solution of anhydrous hydrazine (0.269 g; 0.310 ml; 8.40 mmol) and triethylamine (0.708 g; 0.975 ml; 7.00 mmol) in dry THF (4 ml). Stirring was continued overnight at room temperature. The mixture was filtered and evaporated to a light yellow solid. Recrystallization from hexanes-ethyl/acetate gave pure carbazide 3 (0.533 g; 2.33 mmol; 52%) as a white solid, mp 83°-84° C. TLC (silica gel; CH2Cl2 --CH3OH, 10:1)Rf=0.25-0.35. MS m/e 173 (M+ -56). Analysis: Calculated for C10H19N3O3 : C, 52.39; H, 8.35; N, 18.33. Found: C, 52.08; H, 8.58; N, 18.01; NMR (CDCl3); δ1.43 (9H.S); 2.0-2.3 (4H,m); 3.1-3.4(2H,m); 3.8(2H,bs): 4.3-4.6(1H,m); 6.2(1H,bs); IR(CHCl3 ): 3500-3300, 1730, 1660, 1640 cm-1. [α]D =-46.5±0.5°.

Provenance & Evidence