Triethylamine → tert-butyl N-(4-diazo-3-oxobutan-2-yl)carbamate

Participants

Reaction Conditions

Reaction Steps

To a −15° C. solution of 2-((tert-butoxycarbonyl)amino)propanoic acid (2.5 g, 13.21 mmol) in THF (66 mL) was added Et3N (1.337 g, 13.21 mmol) and ethyl carbonochloridate (1.434 g, 13.21 mmol). The reaction mixture was stirred for 15 min then allowed to warm to 0° C. A solution of diazomethane (prepared according to the standard procedure (Organic Syntheses, Coll. Vol. 5, p. 351 (1973); Vol. 41, p. 16 (1961)) in Et2O (150 mL) was added, until the rich yellow color persisted. The reaction mixture was allowed to warm to rt and stirred for 3 h. Excess CH2N2 was destroyed by the addition of a small amount of aqueous AcOH (20%, 3 mL). The reaction mixture was extracted with saturated NaHCO3 (20 mL), and the organic portion was separated and washed with saturated aqueous NH4Cl (20 mL) and brine (20 mL). The organic portion was separated, dried over Na2SO4, filtered and evaporated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 5-20% EtOAc in petroleum ether) to give (3-diazo-1-methyl-2-oxo-propyl)-carbamic acid tert-butyl ester (2.8 g, 99%) as a brown solid. 1H NMR (DMSO-d6, 400 MHz): δ 7.27 (d, J=7.2, 1H), 6.02 (s, 1H), 4.01 (m, 1H), 1.39 (s, 9H), 1.20 (m, 3H).

Provenance & Evidence