1-Hexamethyleneiminocarboxaldehyde dimethylacetate (3.1 g) in chloroform
(50 ml) was added dropwise at -30°C to a solution of 1’-
ethoxycarbonyloxyethyl 6-aminopenicillanate (5.0 g) and triethylamine (1.9
ml) in chloroform (150 ml) during 15 min. Then, the temperature is allowed
to rise to 0°C during 30 min, and the mixture is stirred at 0°C for another 60
min. Water (120 ml) is added, and stirring is continued for 10 min. The water
phase is separated and the organic layer is washed with water and stripped.
There was obtained 5.0 g of the 1’-ethoxycarbonyloxy-ethyl 6-(hexahydro-1Hazepin-
l-yl) methyleneaminopenicillanate.
