HCID 54403025, compound → HCID 86735837, compound

Participants

Reaction Steps

A solution of 10.45 g of α-ethoxyimino-α-[2-(trichloroethoxycarbonylamino)thiazol-4-yl]acetic acid ethyl ester in a mixture of 10% hydrochloric acid and ethanol is catalytic-hydrogenated over 8.0 g of 5% palladium on charcoal at room temperature under atomospheric pressure. After the absorption of two equivalents of hydrogen, the catalyst in the reaction mixture is filtered off and the filtrate is concentrated to dryness under reduced pressure. By the procedure, 7.43 g of α-amino-α-[2-(trichloroethoxycarbonylamino)thiazol-4-yl]acetic acid ethyl ester hydrochloric acid salt is obtained (yield, 72%). This product is suspended in ethyl acetate and the obtained suspension is washed with saturated sodium bicarbonate aq. solution, washed with water and dried over anhydrous magnesium sulfate. The oily product obtained by the distillation of the solvent, is dissolved in 60 ml of N,N-dimethylformamide and, to the solution is added 4.2 g of tetramethylguanidine and then 3.94 g of t-butyloxycarbonylazide, followed by the stirring for 15 hours at room temperature. The reaction mixture is poured into water and extracted with ethyl acetate. The organic layer is washed with 1 N hydrochloric acid and then saturated NaCl aq. solution and dried over anhydrous magnesium sulfate. The oily product obtained by the distillation of the solvent is purified by a column chromatography packed with silica gel. The procedure gives 4.06 g of α-t-butyloxycarbonylamino-α-[2-(trichloroethoxycarbonylamino)thiazol-4-yl]acetic acid ethyl ester (yield, 46.5%). Melting point: 94°-95° C.

Provenance & Evidence