Abstract The correct structure of the reported 3-aziridinyl-6-chloropyridazine was found to be 3-[β-(1-aziridinyl) ethylamino]-6-chloropyridazine, which was confirmed by nmr studies. The relative ease of nucleophilic displacement of a methylsulfonyl group versus a chloro group in equivalent positions on a pyridazine or a pyrimidine ring was compared. It was observed that the chloro rather than the methylsulfonyl group was preferentially replaced, as ...
![Morpholine,4-[6-(methylsulfonyl)-4-pyrimidinyl]- Structure](https://image.chemsrc.com/caspic/279/90648-76-3.png)