Bis-cyclic amidines are interesting tectones for crystal engineering of molecular solid [1-4], so the study of the efficient procedure for their synthesis is still important. We tried to optimize the synthesis ofbis-(cycloamidin-2-yl)alkanes 1-6 [5-11] using the modification of the thio-Pinner's method. This procedure, usually applied in the synthesis of mono-cyclic amidines, proceeds via in situ activation of a nitrile by sulfur containing catalyst and the subsequent reaction with aliphatic diamine. We used alkanedinitriles and tionatig agents such as S₈, P₄S₁₀, Lawesson Reagent, and Na₂S^.9H₂O, obtaining the highest yields 86-97% for S₈ and P₄S₁₀.

We observed that the strong conjugation between imino double bond and the electron pair on the amino nitrogen limited the reactivity of these compounds. These strong bases with several reagents exclusively give the diprotonated form possessing four N-H protons and anionic equivalents. Even in the reaction with bromine bis-(cycloamidin-2-yl)alkanes force the reduction-oxidation processes to form the tribromide salts 7, 8, 9 with highly ordered, predicted molecular networks in the solid state. The tribromide salt 7 is used as a new convenient source of bromine in aromatic substitution reactions.

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[2] M. W. Hosseini, G. Brand, P. Schaeffer, R. Ruppert, A. De Cian, J. Fischer, Tettrahedron Lett. 1996, 37, 1405.

[3] O. Felix, M. W. Hosseini, A. De Cian, J. Fischer, Tettrahedron Lett. 1997, 38, 1755.

[4] O. Felix, M. W. Hosseini, A. De Cian, J. Fischer, Tettrahedron Lett. 1997, 38, 1933.

[5] P. Oxley, W. F. Short, J. Chem. Soc. 1947, 497.

[6] H. Yamamoto, K. Maruoka, J. Am.Chem. Soc. 1981, 103, 4186.

[7] S. Natsuo, K. Shigeru, N. Kazuhiro, K. Mitsumasa, T. Yoichi, Sh. Tadao, Toho Rayon Co., Ltd.; JP 24965; 1961; Chem. Abstr. 1965, 62, 11820d.

[8] A. Frank, T. Dockner, BASF A.-G.; DE 2512513; 1976; Chem. Abstr. 1977, 86, 29818j.

[9] A. B. P. Lever, B. S. Ramaswamy, S. H. Simonsen, L. K Thompson, Can. J. Chem., 1970, 48, 3076.

[10] H. Lehr, H. Erlenmeyer, Helv. Chim. Acta 1944, 27, 489.

[11] V. B. Piskov, V. P. Kaspierovich, L. M. Yakovleva, Khim. Geterotsikl. Soedin. 1974, 1112.

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