[CH3:1][C:2]1([CH3:23])[S:6][C@@H:5]2[C@H:7]([NH:10]C(CC3C=CC=CC=3)=O)[C:8](=[O:9])[N:4]2[C@H:3]1[C:20]([OH:22])=[O:21].[K].CP(Cl)(CC)=O.CN(C)C1C=CC=CC=1.[P]>C(Cl)Cl.C(O)CCC>[CH3:1][C:2]1([CH3:23])[S:6][C@@H:5]2[C@H:7]([NH2:10])[C:8](=[O:9])[N:4]2[C@H:3]1[C:20]([OH:22])=[O:21]
To a suspension of 14.9 g of penicillin-G-potassium in 60 ml of absolute methylene chloride, 5.06 g (=40 mmols) of methylethylphosphinic acid chloride and 10 ml of dimethylaniline were added in the same manner as indicated in Example 1. The mixture was stirred for 1 hour and the solution of the mixed anhydride so prepared was converted at -5°C with 9.0 g (= 43 mmols) of phosphorus of pentachloride into the imidochloride. After addition of 60 ml of n-butanol and 2 ml of N,N-dimethylaniline, the mixture was stirred at -5°C for 30 minutes. 60 ml of ice water were added and the 6-aminopenicillanic acid was separated at pH 4. 6.47 g (= 76.4 % of the theory) of 6-aminopenicillanic acid were isolated in the form of colorless crystals having a melting point of 195°C (decomposition) which are identical with authentic 6-aminopenicillanic acid according to the IR-spectrum and the mixed melting point.
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