Communication Guanylation of aromatic amines catalyzed by vanadium imido complexes Francisco Montilla * , Antonio Pastor, Agust  ın Galindo Departamento de Qu  ımica Inorg anica, Universidad de Sevilla, Aptdo 553, 41071 Sevilla, Spain Received 13 November 2003; accepted 3 January 2004 Abstract The reaction of formation of guanidines by coupling of carbodiimides and aromatic amines using imido vanadium complexes as catalyst have been investigated. Results demonstrate that the complex V(N-2,6- i Pr 2 C 6 H 3 )Cl 3 is an effective catalyst for this process. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Imido; Vanadium; Guanylation 1. Introduction Reactions involving imido complexes in which the imido moiety undergoes chemical transformations have experienced a remarkable growth in the last years due to the role they play in many important reactions [1,2]. Richeson et al. have recently showed that the guanyla- tion [3] of aromatic amines with carbodiimides is cata- lyzed by imido titanium complexes [4]. The proposed catalytic cycle begins with [2 + 2] addition of the car- bodiimide to the titanium-imido moiety (Scheme 1). The resulting diazametallacyclobutane intermediate, for which exists experimental evidence [4], reacts with the amine affording the corresponding guanidine. On the other hand, recent works have described carbodiimide metathesis reactions catalyzed by group 4 [5] and group 5 [6] imido complexes. Particularly, com- pounds of the formula V(NAr)X 3 (X ¼ Cl, OR) have been successfully employed in this reaction [7]. The proposed catalytic cycle for the process implies the formation of a diazametallacyclobutane intermediate derived from the [2 + 2] cycloaddition between the met- al-nitrogen double bond and the double bond of the unsaturated carbodiimide (Scheme 2). R N C N R Ar NH 2 N R N R NAr H H + R = i Pr, Ar = 2,4,6-Me 3 C 6 H 2 , 2 R = i Pr, Ar = 2-ClC 6 H 4 , 3 R = Cy, Ar = 2,4,6-Me 3 C 6 H 2 , 4 Toluene, Δ [1] (2% mol) ð1Þ * Corresponding authors. Tel.: +34-954-557161; fax: +34-954- 557153. E-mail addresses: montilla@us.es (F. Montilla), galindo@us.es (A. Galindo). L 2 Ti NAr L 2 Ti ArN NR NR R N C N R Ar NH 2 N R N R NAr H H [L= (Me 2 N)C(N i Pr) 2 ] Scheme 1. 0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2004.01.005 Journal of Organometallic Chemistry 689 (2004) 993–996 www.elsevier.com/locate/jorganchem