Organotin(IV) compounds catalyzed cyanide-free synthesis of α-iminonitriles

Two polydentate pro-ligands (H2L1 and H3L2) have been reacted with different organotin(IV) halides such as Ph₂SnCl₂, (t-Bu)₂SnCl₂, and (n-Bu)₂SnCl₂ to synthesize six organotin(IV) compounds, [R₂Sn(L¹)] (R = Ph (1), t-Bu (2), n-Bu (3)) and [R₂Sn(HL²)] (R = Ph (4), t-Bu (5), n-Bu (6)), respectively. All organotin(IV) compounds were characterized by FT-IR spectroscopy, ¹H, ¹³C{¹H}, and ¹¹⁹Sn{¹H} NMR spectroscopy, HR-MS spectrometry, and single-crystal X-ray diffraction analysis. The single-crystal X-ray diffraction analyses reveal that all compounds contain a penta-coordinated tin atom except 1. Compound 1 is hexacoordinated. All organotin compounds show catalytic efficiency towards the synthesis of α-iminonitriles, with a maximum yield of up to 88%. The α-iminonitriles are synthesized from trans-β-nitrostyrene derivatives and 2-aminopyridine derivatives without using any cyanating agent.