Methanol → 7-(2-Methoxyimino-3,3-diethoxy-4-chlorobutyramido)-3-hydroxycepham-4-carboxylic acid

Participants

Reaction Steps

Methanol (40 ml) was added to a solution of 7-amino-3-hydroxycepham-4-carboxylic acid (2 g) and sodium bicarbonate (0.57 g) in water (13.4 g) under ice-cooling. A solution of 2-methoxyimino-3,3-diethoxy-4-chlorobutyryl chloride (syn isomer, 1.34 g) in dry tetrahydrofuran (2 ml) was added to a solution while adjusting pH 6.5 to 7.8, then and stirred under ice-cooling for three hours. After adjusting the resultant mixture to pH 7.5, the solvent was removed in vacuo. The aqueous residue was adjusted to pH 7.5 under ice-cooling, and diisopropyl ether (10 ml) was added to the solution. After the aqueous solution was separated, ethyl acetate (20 ml) was added to the aqueous solution, and adjusted to pH 2.0 with 20% sulfuric acid. The ethyl acetate layer was separated and the aqueous solution was extracted with ethyl acetate (10 ml) twice. The ethyl acetate layer and the extract were combined, washed with a saturated aqueous solution of sodium chloride and dried over magnesium sulfate. The solution was concentrated in vacuo to give 7-(2-methoxyimino-3,3-diethoxy-4-chlorobutyramido)-3-hydroxycepham-4-carboxylic acid (syn isomer, 2.97 g).

Provenance & Evidence