Carbon Dioxide → 4-Cyclopropylaminocarbonyl-2-isopropyloxazole-5-carboxylic acid

Beteiligte Stoffe

Reaktionsschritte

0.12 mol of n-butyllithium (80.0 ml of a 1.5 molar solution in hexane) was added dropwise to a solution of 10.4 g (0.054 mol) of 2-(1-methylethyl)-oxazole-4-carboxylic acid cyclopropylamide in 250 ml of tetrahydrofuran under a nitrogen atmosphere of -70° C. and stirring was carried out for 30 minutes at this temperature. Thereafter, the reaction mixture was poured onto 500 g of solid CO2 and was left to stand overnight. The mixture was evaporated down, the residue was taken up in 200 ml of water and 30 ml of 10% strength NaOH, the solution was extracted twice with diethyl ether and the aqueous phase was acidified to pH 2 with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase was dried with magnesium sulfate and the solvent was stripped off under reduced pressure. 10.4 g (81%) of 4-cyclopropylaminocarbonyl-2-(1-methylethyl)-oxazole-5-carboxylic acid were obtained as a white powder of melting point 109° -112° C.

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