A new, highly efficient allylation reagent—lithium allyldibutylmagnesate (allylBu 2MgLi)—was obtained by mixing allyl-magnesium chloride (1 equiv) and n-BuLi (2 equiv). N-Lithiated and N-methyl substituted 1 H-pyridine-2-thiones and -ones were successfully and regioselectively allylated by treatment with allylBu 2MgLi yielding 6-allyl-3,6-dihydro-1 H-pyridine-2-(thio)ones and 4-allyl-3,4-di-hydro-1 H-pyridine-2-(thio)ones. The latter were formed by a 3,3-sigmatropic Cope rearrangement of the former.