Syntheses and metalation of pyridazinecarboxamides and thiocarboxamides. Diazines. Part 32

The syntheses of new pyridazinethiocarboxamides are described using the reaction of Lawessonʹs reagent with pyridazine carboxamides or by reacting lithiopyridazines with phenylisothiocyanate. Metalation of 3-N-tert-butylpyridazinethiocarboxamides and carboxamides with LTMP followed by reaction of the lithio derivatives with various electrophiles gave access to a wide range of polysubstituted pyridazines. An unexpected regioselectivity at the meta position of the thiocarboxamide group was observed and explained.