Securopen,Bayer,W. Germany,1977
3.8 parts by weight of D-(-)-α-[(imidazolidin-2-on-1-yl)carbonylamino]phenylacetic
acid were dissolved in 65 parts by volume of dichloromethane. 2.7
parts by weight of 1-methyl-2-chloro-δ1-pyrrolinium chloride were added, and
after cooling to -10°C 2.0 parts by volume of triethylamine were added
gradually. This reaction mixture was then stirred for one hour at -5°C
(mixture A). 4.0 parts by weight of 6-aminopenicillanic acid in 80 parts by
volume of dichloromethane were treated with 4.4 parts by volume of
triethylamine and 4.0 parts by weight of anhydrous sodium sulfate and then
stirred for two hours at room temperature. After filtration, the solution was
cooled to -20°C and combined with the mixture A. The reaction mixture was
left to reach 0°C of its own accord, and was then stirred for a further hour at
0°C. The solvent was removed in a rotary evaporator, the residue was
dissolved in water, and the solution was covered with a layer of ethyl acetate and acidified with dilute hydrochloric acid at 0° to 5°C, while stirring, until pH
1.5 was reached. The organic phase was then separated off, washed with
water, dried over magnesium sulfate while cooling, and filtered, and after
dilution with an equal amount of ether the sodium salt of the penicillin was
precipitated from the filtrate by adding a solution of sodium 2-ethylcaproate
dissolved in ether containing methanol. Yield: 1.3 parts by weight.
