The application of N-Heterocyclic carbenes (NHCs) in synthetic manipulations has continuously grown since their first isolation in 1992 by Arduengo and coworkers.(1) NHCs are commonly used as strong Brønsted and Lewis bases, and as ligands in transition metal and metal-free catalytic reactions. Such catalytic reactions include oxidation reactions where an external oxidant, such as a quinone, is required. Interestingly, the reactivity between the strong nucleophilic NHCs and electrophilic quinones has not been previously studied. For 1,2-chloranil and 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ), the products formed with NHCs are distinct from those arising from the nucleophilic attack of quinones by other P- or N-centered nucleophiles like phosphines and pyridines.(2) Novel unexpected π-conjugated materials were isolated.

1. A. J. Arduengo III, H. V. R. Dias, R. L. Harlow and M. Kline, J. Am. Chem. Soc., 1992, 114, 5530–5534.
2. (a) F. Ramirez, D. Rhum and C. P. Smith, Tetrahedron, 1965, 21, 1941–1959.; (b) V. A. Loskutov, V. I. Mamatyuk and I. V. Beregovaya, Russ. Chem. Bull., 1999, 48, 371–374.; (c) A. S. Koch, W. G. Harbison, J. M. Hubbard, M. de Kort and B. A. Roe, J. Org. Chem., 1996, 61, 5959–5963.; (d) A. R. Katritzky, W.-Q. Fan, Q.-L. Li and S. Bayyuk, J. Heterocyclic Chem, 1989, 26, 885–892.