Benzaldehyde → Diphenylmethyl 7-Benzylideneamino-3-(3-chloro-1-propen-1-yl)-3-cephem-4-carboxylate

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Reaction Steps

To an ice-cooled mixture of the crystalline 7-aminocephem intermediate XVIII (Z isomer) (13.4 g, 28 mmole) and benzaldehye (3.3 g, 31 mmole) in ethyl acetate (150 ml) was added dropwise 0.5N sodium hydroxide (56 ml, 28 mmole) over a period of 20 minutes, to maintain the temperature of the reaction mixture below 10° C. The mixture was stirred with cooling for another 15 minutes, and the organic layer was separated, washed with saturated aqueous sodium bicarbonate (100 ml×2) and dried over magnesium sulfate. To the dried solution was added a small amount of charcoal and the mixture was filtered. The filtrate was concentrated to dryness. The residual oil was dissolved in carbon tetrachloride (50 ml), and concentrated again. This procedure was repeated 3 times, and the mixture was monitored by reverse phase tlc to confirm that all of the starting 7-aminocephalosporin was converted to the Schiff's base. Removing the solvent in vacuo gave 16.45 g of the title compound XVII (Z isomer) as a pale yellow powder (estimated purity 85%; M.p. 74° C. (dec.), which was used for the next step without purification.

Provenance & Evidence