Summary: a, w Aliphatic diamines were cyclized to heterocyclic amines by being heated at 180" C for 5 h with RuC12 (Ph3P), in diphenyl ether. Primary amines having an cr-hydrogen atom are converted to symmetrical tertiary amines by being heated at 185 or 235" C for 8 h with RuC13. 3H20 and Ph3P in THF solution.