Ru/C catalyzed cyclization of linear α,ω-diamines to cyclic amines in water

A facile and convenient way to prepare cyclic amines in water was achieved by the catalyst system composed of Ru/C and Al powder. The α,ω-diaminoalkanes, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diamino-heptane were converted to corresponding cyclic amines in good yields. The use of D2O provided a novel route to obtain deuterated cyclic amines in good yields.