An efficient iminophosphorane-mediated synthesis, NMR–IR spectroscopic and X-ray study of novel ferrocenylimidazole derivatives: Part 10. Study on ferrocenes

Starting from ethyl β-ferrocenyl-α-azidoacrylate (2), a series of novel 4-ferrocenylidene-1-aminoimidazolones (6a–j) was prepared in a pathway involving an aza-Wittig reaction followed by condensation of the resulting carbodiimidoester with hydrazines. Formation of [1,2,4]triazines of type 7 was not observed. Simultaneously with the formation of 2, an interesting transformation was also observed to afford a novel imidazolone derivative (3) containing two ferrocenyl groups. The structures of the products were determined by IR, 1H- and 13C-NMR spectroscopy (including 2D-COSY, DEPT, 2D-HMQC, and 2D-HMBC measurements), and in the case of compound 3 also by single-crystal X-ray analysis.