Synthesis and characterization of 1,1′-bis[(N-methyl-N-phenyl)aminomethyl(ethyl)]ferrocenes. Crystal structures of [Fe{(η5–C5H4)–C(C6H5)N–CH2C6H4CH3-4}2] and 2[Fe{(η5–C5H4)–CH2N(CH3)–C6H4OCH3-4}2] · 1/4H2O

Direct or catalytic condensation of diacylferrocenes (acyl = formyl, acetyl, and benzoyl) and anilines or benzylamines with titanium tetrachloride as a catalyst resulted in the corresponding diimines 1–3, respectively. Reduction of these imines with sodium borohydride or lithium aluminum hydride/aluminum chloride in THF yielded 1,1′-bis[(N-phenyl)aminomethyl(ethyl)]ferrocenes (4, 5) and 1,1′-bis[(N-benzyl)aminobenzyl]ferrocenes (6), respectively. Reductive methylation of 4–6 with aqueous formaldehyde, cyanoborohydride and acetic acid only afforded 1,1′-bis[(N-methyl-N-phenyl)aminomethyl(ethyl)]ferrocenes (7, 8). 1,1′-Bis[{(N-methyl-N-benzyl)amino}benzyl]ferrocenes (9) were not obtained, probably due to their debenzylation under the acidic conditions. The molecular structures of 3g and 7a were determined by single crystal X-ray analysis.

Graphical abstract1,1′-Bis[(N-methyl-N-phenyl)aminomethyl(ethyl)]ferrocenes (7, 8) were synthesized by reductive methylation of 1,1′-bis[(N-phenyl)aminomethyl(ethyl)]ferrocenes (4, 5). The latter were obtained by reduction of 1 and 2 with sodium borohydride or lithium aluminumhydride–aluminum chloride. 1,1′-Bis[{(N-methyl-N-benzyl)amino}benzyl]ferrocenes (9) were not obtained, probably due to their debenzylation under the acidic conditions. The structures of 3g and 7a were determined by single crystal X-ray analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide