Abstract The reaction of n-butyllithium with 1, 3-benzodioxole, 1, 3-benzoxathiole, and their 2, 2-dimethyl derivatives has been investigated. Except with 1, 3-benzoxathiole there is competition between metalation and cleavage of the ether bond. Metalation occurs ortho to the oxygen, while cleavage gives substitution, elimination and reduction products.