Interaction of 2,4,6‐heptanetrione with 1,5‐diamino‐3‐azapentane and similar polyamines. The crystal and molecular structure of a new heterocyclic compound

The pathway of the reaction between 2,4,6‐heptanetrione and 1,5‐diamine‐3‐aza‐pentane was studied and some products identified by ir, uv, mass spectra and x‐ray diffractometry. This reaction is not a simple condensation with the formation of a Schiff base but a more complicated process. The structure of the final compound was determined by x‐ray crystallography and refined to R = 0.047. Crystals are triclinic, space group Pl, with a = 11.795(5), b = 9.779(5), c = 7.801(5) Å, α = 101.74(3), β = 90.93(3), γ = 110.65(3), Dx = 1.27 g. cm −3 for Z = 2. The structure is essentially formed by three heterorings two of which have a common edge. Only the 4‐pyridone ring is planar. As expected 1,5‐diamino‐3‐thiapentane reacts with the same triketone, in 1:1 or 1:2 molar ratios, to give the acyclic or macrocyclic Schiff bases.