J. Org. Chem. zyxwvu 1992,57,5069-5071 Reaction of Fullerenes and Benzyne Steven H. Hoke 11, Jay Molstad, Dominique Dilettato, Mary Jennifer Jay, Dean Carlson, Bart Kahr,* and R. Graham Cooks* Department of Chemistry, Purdue University, West Lafayette, Indiana zyxwvu 47907-1393 Received May zyxwvutsrq 29,1992 Summary: Benzyne reacts with C, to form a series of compounds [C, zyxwvutsrq + (C6H&], n = 1,2,3,4, identified by maw spectrometry; the monoaddition product was isolated by chromatography and structurally characterized by 'H- and 13C-NMR spectroscopies. Electron-deficient pyracyclene bonds are the sites of attachment in the preponderance of fullerene addition reactions. Metal reagents add here,' as do a variety of dienes and dipolar compounds,2 ~ a r b e n e s , ~ and oxygen atoms.4 However, o-benzyne typically reacts with poly- cyclic aromatic compounds by adding across the l,4-pos- itions within a ring, not between rings, thus participating in [2 + 41 cycloaddition reactions! The common 1,Zmode of attachment to C, might not be the exclusive regio- chemistry followed in a reaction of benzyne with buck- minsterfullerene. Here, we describe the preparation of benzyne adducts of C, and C70, as well as the isolation of the monoaddition product zyxwvutsrq (m/z 796) to Ceo and its spec- troscopic characterization. Fullerenes were prepared and purified using standard procedures described previously.6 A benzene solution containing C, and isoamylnitrite was stirred vigorously. Benzyne, 10 equiv, was generated in situ by adding an- thranilic acid at room temperat~re.~ Mass spectrometric analysiss of the reaction mixture showed that -72% of the C, had been consumed, of which -45% was converted to monobenzyne product (m/z 796), -38% to dibenzyne product (m/z 872), -12% to tribenzyne product zyxwvutsrqp (m/z 9481, and -2% to tetrabenzyne (1) Hawkins, J. M.; Lewis, T. A.; Loren, S. D.; Meyer, A.; Heath, J. R.; Shibato, Y.; Saykally, R. J. J. Org. Chem. 1990,55,6250. Hawkins, J. M.; Meyer, A.; Lewis, T. A.; Loren, S.; Hollander, F. J. Science 1991,252,312. Fagan, P. J.; Calabrese, J. C.; Malone, B. Science 1991,252,1160. Balch, A. L.; Catalano, V. J.; Lee, J. W. Inorg. Chem. 1991,30,3980. Balch, A. L.; Catalano, V. J.; Lee, J. W.; Olmstead, M. M.; Parkin, S. R. J. Am. Chem. SOC. 1991,113,8953. Fagan, P. J.; Calabrese, J. C.; Malone, B. J. Am. Chem. SOC. 1991,113,9408. Koefod, R. S.; Hudgens, M. F.; Shapley, J. R. J. Am. Chem. zyxwvutsrqpo SOC. 1991,113,8957. See also: Fagan, P. J.; Calabrese, J. C.; Malone, B. Acc. Chem. Res. 1992, 25, 134. Hawkins, J. M. Acc. Chem. Res. 1992,25, 150. (2) Wudl, F. In Fullerenes; Hammond, G. S., Kuck, V. J., Eds.; Am- erican Chemical Society: Washington, 1992. See also: Wudl, F. Acc. Chem. Res. 1992,25, 134 and references cited therein. (3) Suzuki, T.; Li, Q.; Khemani, K. C.; Wudl, F.; Almamon, 0. Science 1991,254,1186. (4) Wood, J. M.; Kahr, B.; Hoke, S. H., II; Dejarme, L.; Cooks, R. G.; Ben-Amotz, D. J. Am. Chem. SOC. 1991, 113, 5907. Creegan, K. M.; Robbins. J. L.: Robbins. W. K.: Millar. J. M.: Sherwood. R. D.: Tindall. P. J.; Cox, D. 'M.; Smith, A. B:, 111; McCauley, J. P., Jr.; Jones, D. R.; Gallagher, R. T. J. Am. Chem. SOC. 1992,114,1103. Elemes, Y.; Silver- man, s. K.; Sheu, C.; Kao, M.; Foote, C. s.; Alvarez, M. M.; Whetten, R. L. Angew. Chem., Int. Ed. Engl. 1992,31, 351. (5) Hoffmann, R. W. Dehydrobenrene and Cycloalkynes; Academic Press: New York, 1967; pp 200-239. (6) Haufler, R. E.; Conceicao, J.; Chibante, L. P. F.; Chai, Y.; Byme, N. E.; Flanagan, S.; Haley, M. M.; O'Brien, S. C.; Pan, C.; Xiao, Z.; Billups, W. E.; Ciufolini, M. A.; Hauge, R. H.; Margrave, J. L.; Wilson, L. J.; Curl, R. F.; Smalley, R. E. J. Phys. Chem. 1990, 94, 8634. Ben- Amotz, D.; Cooks, R. G.; Dejarme, L.; Gunderson, J. C.; Hoke, S. H., 11; Kahr, B.; Payne, G. L.; Wood, J. M. Chem. Phys. Lett. 1991,183, 149. (7) Friedman, L.; Logullo, F. M. J. Am. Chem. SOC. 1963,85,1549. Ceo (10 mg, 0.014 mol) was dissolved in 40 mL of methylene chloride in a 100-mL round-bottom flask fitted with a drying tube. Isoamyl nitrite (20 mL, 0.014 mol) was added via syringe. Anthranilic acid (20 mg, 0.015 mol) waa added aa a solid, and the reaction mixture was stirred for 3 h at room temperature, after which the mixture had aasumed a deep brown color. The solution waa then concentrated by evaporation. 0022-326319211957-5069$03.00/0 5069 I 720 'r 8 900 loo0 11w 1200 mass-tocharge Figure 1. Electron attachment maas spectrums of the benzyne adducts of cm: m/z 720 = cm, m/z 796 = cm + C6H4, mlz 872 = Cm + (C6H4)2, m/z 948 = Cm + (CeH4)3, m/z 1024 = Cm + (C6H414. I . 9 . 1 I I 0 5 10 15 20 25 30 Time (min.) Figure 2. High-performance liquid ~hromatogram'~ showing the peaks corresponding to the dibenzyne adducts (I), monobenzyne adduct (111, and Cm (111). product (m/z 1024) (Figure l).9 Fragmentation of the benzyne adducts by tandem mass Spectrometry'O occurs by successive losses of benzyne, ultimately restoring CW The major peaks in the spectrum are associated with (8) Mass spectra were recorded using a Finnigan TSQ Model 700. Samples were introduced by desorption from a probe which was ramped from ambient temperature to zyxw 800 OC in 20 a. Electron attachment was performed using NH, as a reagent gas to moderate electron energies and to allow nondissociative electron attachment. See: von Ardenne, M.; Steinfelder, K.; Tummler, R. Elektronenanlagerungs-massenspektro- metric Organischer Substanren; Springer-Verlag: Berlin, 1971. Hunt, D. F.; Sethi, S. K. J. Am. Chem. SOC. 1980,102,6953. Dillard, J. G. Chem. Rev. 1973, 73, 589. (9) Yields were estimated by integrating the respective mass chroma- tograms over the full desorption profile and assuming equal ionization and transmission efficiencies. 0 1992 American Chemical Society