N,N-Dimethylaniline → 6-Aminopenicillanic acid

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Reaction Steps

To a suspension of 6β-phenylacetamidopenicillanic acid potassium salt (1 mmol.) and N,N-dimethylaniline (3 mmol.) in 6 ml. of dry methylene chloride under nitrogen at 0° there is added 1 mmol. of trimethylsilyl chloride. The mixture is stirred for 30 minutes. Then a solution of 1.26 ml. of 12.5% phosgene in benzene is added to the above trimethylsilyl ester mixture. This reaction mixture is stirred at 0° for 2 hours and then the solvents are removed in vacuo. Fresh dichloromethane (6 ml.) is added followed by 2 mmol. of N,N-dimethylaniline and then 2 mmol. of o-aminothiophenol. The mixture is stirred at 0° for 2 hours and then diluted with aqueous sodium bicarbonate solution and dichloromethane to adjust the pH to 7.5-8.0. The aqueous layer is extracted twice with dichloromethane, cooled in an ice-water bath, and then acidified to pH4. The resulting precipitate is collected, washed with acetone:water (1:1) and then acetone, and finally dried to give the desired product, 6β-aminopenicillanic acid.

Provenance & Evidence