Pyridine → (2,6-dioxomorpholinoethyl)-N3-(ethoxycarbonylmethyl)-3,6-diazaoctanedioic acid

Participants

Reaction Steps

A suspension of 21.1 g (50 mmol) of N3,N6 -bis-(carboxymethyl)-N9 -(ethoxycarbonylmethyl)-3,6,9-triaza undecanedioic acid (J. Pharm. Sci. 68, 1979, 194) in 250 ml of acetic anhydride is stirred, after the addition of 50 ml of pyridine, for 3 days at room temperature. Then the precipitate is suctioned off, it is washed three times, each time with 50 ml of acetic anhydride and it is finally stirred up for several hours with absolute diethyl ether. After suctioning off, washing with absolute diethyl ether and drying in a vacuum at 40° C., 18.0 g (=89% of theory) of a white powder with a melting point of 195°-196° C. is obtained.

Provenance & Evidence