Palladium-Catalyzed [2 + 2 + 2] Cycloadditions of 3,4-Didehydrophenanthrene and 1,2-Didehydrotriphenylene Carmen Romero, Diego Pen ˜a,* Dolores Pe ´rez,* and Enrique Guitia ´n Departamento de Quı ´mica Orga ´nica, UniVersidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain qodpena@usc.es; qodolopm@usc.es ReceiVed June 26, 2008 Palladium-catalyzed [2 + 2 + 2] cycloaddition reactions of 3,4-didehydrophenanthrene (3,4-phenanthryne) and 1,2-didehydrotriphenylene (1,2-triphenylyne) afford sterically congested polycyclic aromatic hydrocarbons with novel structures. Introduction In recent years, interest in fullerenes, nanographenes, and carbon nanotubes has led to a remarkable revival in the development of methods for the preparation of large and/or sterically congested polycyclic aromatic hydrocarbons (PAHs). 1 Aryne-based reactions 2 have been extensively used for this purpose; 3 in particular, our group has applied the palladium- catalyzed cyclotrimerization of arynes to the synthesis of a number of strained or large PAHs. 4-6 Recently, we reported the generation and palladium-catalyzed [2 + 2 + 2] cycloaddition reactions of 2,3-didehydrotriph- enylene (2,3-triphenylyne) to afford planar extended triph- enylenes. 7 In this paper, we describe cyclotrimerization reactions of 3,4-didehydrophenanthrene (3,4-phenanthryne, 1, Scheme 1) and 1,2-didehydrotriphenylene (1,2-triphenylyne, 2) to yield nonplanar extended polyarenes, 8 increasing the scope of this synthetic methodology. Based on our experience in this field, (1) (a) Watson, M. D.; Fechtenko ¨ tter, A.; Mu ¨llen, K. Chem. ReV. 2001, 101, 1267. (b) Harvey, R. G. Curr. Org. Chem. 2004, 8, 303. (c) Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. ReV. 2004, 104, 4891. (d) Grimsdale, A. C.; Mu ¨llen, K. Angew. Chem., Int. Ed. 2005, 44, 5592. (e) Pascal, R. A., Jr. Chem. ReV. 2006, 106, 4809. (f) Wu, J.; Pisula, W.; Mu ¨llen, K. Chem. ReV. 2007, 107, 718. (g) Anthony, J. E. Angew. Chem., Int. Ed. 2008, 47, 452. (2) For some reviews of aryne reactivity, see: (a) Hoffmann, R. W. Dehydrobenzene and Cycloalkynes; Academic Press: New York, 1967. (b) Pellissier, H.; Santelli, M. Tetrahedron 2003, 59, 701. (3) For some recent examples, see: (a) Lu, J.; Zhang, J.; Shen, X.; Ho, D. M.; Pascal, R. A., Jr. J. Am. Chem. Soc. 2002, 124, 8035. (b) Duong, H. M.; Bendikov, M.; Steiger, D.; Zhang, Q.; Sonmez, G.; Yamada, J.; Wudl, F. Org. Lett. 2003, 5, 4433. (c) Wang, D. Z.; Katz, T. J.; Golen, J.; Rheingold, A. L. J. Org. Chem. 2004, 69, 7769. (d) Lu, J.; Ho, D. M.; Vogelaar, N. J.; Kraml, C. M.; Pascal, R. A., Jr. J. Am. Chem. Soc. 2004, 126, 11168. (e) Dolbier, W. R., Jr.; Zhai, Y.-A.; Battiste, M. A.; Abboud, K. A.; Ghiviriga, I. J. Org. Chem. 2005, 70, 10336. (f) Sygula, A.; Sygula, R.; Rabideau, P. W. Org. Lett. 2005, 7, 4999. (g) Sygula, A.; Sygula, R.; Rabideau, P. W. Org. Lett. 2006, 8, 5909. (h) Wang, Y.; Stretton, A. D.; McConnell, M. C.; Wood, P. A.; Parsons, S.; Henry, J. B.; Mount, A. R.; Galow, T. H. J. Am. Chem. Soc. 2007, 129, 13193. (4) (a) Pen ˜a, D.; Escudero, S.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. Angew. Chem., Int. Ed. 1998, 37, 2659. (b) Pen ˜a, D.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. J. Am. Chem. Soc. 1999, 121, 5827. (5) (a) Pen ˜ a, D.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. Org. Lett. 1999, 1, 1555. (b) Pen ˜a, D.; Cobas, A.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. Org. Lett. 2000, 2, 1629. (c) Pen ˜a, D.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. J. Org. Chem. 2000, 65, 6944. (d) Pen ˜a, D.; Cobas, A.; Pe ´rez, D.; Guitia ´n, E.; Castedo, L. Org. Lett. 2003, 5, 1863. (e) Iglesias, B.; Cobas, A.; Pe ´rez, D.; Guitia ´n, E.; Vollhardt, K. P. C. Org. Lett. 2004, 6, 3557. (f) Caeiro, J.; Pen ˜a, D.; Cobas, A.; Pe ´rez, D.; Guitia ´n, E. AdV. Synth. Catal. 2006, 348, 2466. (6) For a review of palladium-catalyzed cycloaddition reactions of arynes, see: Guitı ´an, E.; P ´ erez, D.; Pen ˜a, D. In Topics in Organometallic Chemistry; Tsuji, J., Ed.; Springer-Verlag: Weinheim, 2005; Vol. 14, pp 109-146. (7) Romero, C.; Pen ˜a, D.; Pe ´rez, D.; Guitia ´n, E. Chem.sEur. J. 2006, 12, 5677. SCHEME 1. Arynes 1 and 2 and Aryne Precursors 3 and 4 10.1021/jo8013947 CCC: $40.75  2008 American Chemical Society 7996 J. Org. Chem. 2008, 73, 7996–8000 Published on Web 09/17/2008