Methyl acetoacetate → 6-(2-[4-Aminomethylphenyl]acetamido)-2,2-dimethyl-3-(5-tetrazolyl)penam

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Reaction Steps

Sodium 4-[(1-methoxycarbonyl-2-propenyl)aminomethyl]phenylacetate is prepared from 4-aminomethylphenylacetic acid [Zaugg and Horrom, J. Am. Chem. Soc. 80, 4317 (1958)] and methyl acetoacetate by the method described by Dane and Dockner [Chem. Ber., 98, 789 (1965)]. A suspension of this salt (2.15 g, 7.5 mmole), 7 drops of N-methylmorpholine and 100 ml. of tetrahydrofuran is stirred at -20° C.; ethyl chloroformate (0.81 g. 7.5 mmole) is added and the mixture is stirred for 60 minutes. 6-Amino-2,2-dimethyl-3-(5-tetrazolyl)penam (1.80 g., 7.5 mmoles) is suspended in a 50:50 mixture of tetrahydrofuran and water (40 ml), and the pH is adjusted to 7.5 with 1 N sodium hydroxide solution whereby a homogeneous solution is obtained. This is added to the above suspension, in one portion, the new mixture is stirred at -20° C. for 1 hour and then it is allowed to warm to room temperature over 1 hour. Most of the tetrahydrofuran is removed in vacuo, the resultant aqueous solution is cooled in an ice bath, and the pH is adjusted to 1.5 with 3 N hydrochloric acid. After 30 minutes the pH is adjusted to 2.5, and the solution is extracted with ethyl acetate. The aqueous phase is adjusted to pH 6.0 and freeze-dried. The resultant lyophylate is combined with that from another preparation (5 mmoles) and chromatographed on Sephadex LH-20 (150 g) eluting with water. Like fractions (tlc analysis) are combined and freeze-dried, yielding the title compound as a colorless amorphous solid (570 mg., 11% yield), m.p. 190°-200° C. IR(KBr): 1770, 1650 and 1515 cm-1. NMR (DMSO-d6 -D2O): 7.4 ppm (s, 4H), 5.65 ppm (d, J=4 Hz, 1H), 5.45 ppm (d, J=4 Hz, 1H), 5.2 ppm (s, 1H), 4.1 ppm (s, 2H), 3.6 ppm (s, 2H), 1.6 ppm (s, 3H) and 1.0 ppm (s, 3H).

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