Synthesis of nitrogen-containing 15-membered triacetylenic macrocycles.: Stable complex with palladium(0)

Selective and efficient preparation of a new type of nitrogen-containing 15-membered triacetylenic macrocycles named 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triynes (1) (Ar-1 = Ar-2 = Ar-3 = 4-methylphenyl, 1aaa; Ar-1 = Ar-2 = 4-methylphenyl, Ar-3 = ferrocenyl, 1aab) has been achieved. Macrocycle 1aaa forms a very stable complex with Pd-0, being the first palladium(0) complex with a macrocyclic triyne. The three triple bonds in 1aaa are responsible for the complexation. The X-ray structures of both the ligand 1aaa and its Pd-0 complex are presented. Furthermore, compound 1aaa undergoes cycloisomerization into the corresponding 2,5,8-tris[(4-methlphenyl)sulfonyl]-2,5,8-triazatrindane, 11aaa, when treated with Pd(PPh3)(4) in refluxing toluene.