N,N-Dimethylaniline → (2R,3S,5R,6R) 2-(N-Acetyl)carbamoyloxymethyl-6-[(R)-2-Amino-2-phenylacetamido]-2-methylpenam-3-carboxylic Acid p-Nitrobenzyl Ester

Participants

Reaction Steps

A solution of (2R,3S,5R,6R) 2-(N-acetyl)carbamoyloxymethyl-6-amino-2-methylpenam-3-carboxylic acid p-nitrobenzyl ester (0.80 gm, 1.77 mmol) in methylene chloride (10 ml) was cooled to 2° and dimethylaniline (0.214 gm, 1.77 mmol) was added. To the stirred mixture was added (-)-phenylglycyl chloride hydrochloride (0.392 gm, 1.83 mmol) in two equal portions. The first portion was added at 2° and the reaction mixture was gradually warmed to 20° over a 90 minute period. The reaction did not appear to begin at the lower temperatures. The second portion of the acid chloride was added at 20° and the reaction mixture was stirred at room temperature for 41/2 hours. Water (10 ml) was added and, with thorough mixing, the pH was adjusted to 1.7. The layers were separated, the water layer was washed with methylene chloride, and the methylene chloride layer was washed with pH 2.0 buffer. The aqueous layers were combined, adjusted to pH 7.0 with 10% KOH solution, and extracted with methylene chloride (2×10 ml). The methylene chloride extracts were combined, dried over molecular sieves and concentrated in vacuo to about 15 ml. This solution was added dropwise to 300 ml of stirring heptane and produced a fine white amorphous solid. This was removed by filtration and dried to give 0.61 gms of the title product. The purity was estimated from its nmr spectrum to be about 60%.

Provenance & Evidence