Pyridazines. Part 25: Efficient and selective deprotection of pharmacologically useful 2-MOM-pyridazinones using Lewis acids

An efficient and selective procedure for the cleavage of a methoxymethyl group at the 2-position in acid-sensitive pyridazinones is presented. Deprotection with Lewis acids (boron tribromide or aluminium chloride) affords 3(2H)-pyridazinones under mild conditions without affecting multiple bonds in substituents.