Ferrocenylamines 2. Reductive methylation of secondary ferrocenylamines and ferrocenylaldimines: Synthesis, characterization of [(N-methyl-N-aryl)amino]methylferrocenes, 1-[(N-methyl-N-phenyl)amino]ethylferrocene and crystal structures of [(η5-C5H5)Fe(η5-

The reactions of ferrocenylaldimines (II) [(η5-C5H5)Fe(η5-C5H4CHNC6H4-R)] (R = 4-CH3O (a), 4-CH3 (b), H (c), 4-Cl (d), 3-Cl (e), 4-NO2 (f), 3-NO2 (g)) and ferrocenylketimine (I) [(η5-C5H5)Fe (η5-C5H4CH3CNC6H5)] with sodium borohydride in ethanol or lithium aluminum hydride in THF resulted in secondary ferrocenylamines 3, 4. Reductive methylation of 3 (or II) and 4 with aqueous formaldehyde and sodium cyanoborohydride all gave out corresponding N-methylated tertiary ferrocenylamines 5 [(η5-C5H5)Fe(η5-C5H4CH2N(CH3)C6H 4-R)] (R = same as above mentioned) and 2, respectively, in good yields. All these tertiary ferrocenylamines 3–5 were characterized structurally. The crystal structures of 3d and 5a were also determined. Compound 3d is monoclinic, space group P2(1)/n, with a = 9.7585(14) Å, b = 11.5267(17) Å, c = 13.0830(19) Å and β = 97.969(2)°. Compound 5a is orthorhombic, space group Pccn, with a = 13.752(2) Å, b = 22.095(3) Å, c = 10.6421(16) Å.

Graphical abstractReduction of ferrocenylimines II, I with NaBH4 or LiAlH4 resulted in secondary ferrocenylamines 3, 4. Reductive methylation of secondary ferrocenylamines 3, 4 with aqueous formaldehyde, sodium cyanoborohydride and acetic acid both gave out corresponding N-methylated tertiary ferrocenylamines 5, 2. Reductive methylation of ferrocenylaldimines II also yielded 5. The crystal structures of 3d, 5a were determined.Figure optionsDownload full-size imageDownload as PowerPoint slide