Hydrogen Bromide → HCID 131713218, compound

Participants

Reaction Steps

2.72 ml of a 0.46 M HBr solution in CH2Cl2 (1.25 mol equivalents) are added, while stirring, to a solution, cooled with ice, of 497 mg of 7β-[2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-cephem-4-carboxylic acid pivaloyloxymethyl ester (free base) in 5 ml of CH2Cl2. After stirring for 10 minutes, 35 ml of diethyl ether are added to the solution and a precipitate forms. The mixture is stirred for a further 1/2 hour at 0°, the precipitate is filtered off, washed with diethyl ether and dried on a suction filter. The resulting faintly orange powder is dissolved in 2.5 ml of CH2Cl2, whereupon the product recrystallises. After the addition of 5 ml of CH2Cl2, the mixture is stirred for one hour while cooling with ice. Filtration, washing of the resulting crystals with CH2Cl2 and diethyl ether and drying in a high vacuum yield the 7β-[2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-cephem-4-carboxylic acid pivaloyloxymethyl ester hydrobromide in syn-form having a melting point of 215° (with decomposition).

Provenance & Evidence