S. K. Akubathini, E. Biehl / Tetrahedron Letters 50 (2009) 1809–1811
1811
Table 1 (continued)
Entry
R
Alkyne
Product
Yielda (%)
59
MeO
17
18
3-OMe
O2N
MeO
3-OMe
97
89
NO2
19
4,5-Dimethyl
CH3
20
21
22
23
24
25
4,5-Dimethyl
4,5-Dimethyl
4,5-Dimethyl
4,5-Dimethyl
4,5-Dimethyl
4,5-Dimethyl
96
92
97
65
97
84
H3C
F
F
OMe
OMe
OEt
O
EtO
O
O2N
NO2
MeO
OMe
Reaction conditions: benzyne precursor (1.2 equiv), terminal alkyne (1.0 equiv), CsF (2.4 equiv), CuI (0.1 equiv), toluene/CH3CN 3:3 mL, 150 °C, 30 min.
a
Isolated yield.
T. L. In The Chemistry of Triple-bonded Functional Groups; Supplement, C., Patai, S.,
Rappoport, Z., Eds.; The Chemistry of Functional Groups Series; John Wiley and
Sons: New York, 1983; Vol. 1, pp 383–419; (c) Hart, H. In The Chemistry of Triple-
bonded Functional Groups; Supplement, C., Patai, S., Rappoport, Z., Eds.; The
Chemistry of Functional Groups Series; John Wiley and Sons: New York, 1983;
Vol. 2, pp 1017–1134; (d) Castedo, L.; Guitan, E. In Studies in Natural Products
Chemistry; Rahman, Atta-ur, Ed.; Stereoselective Synthesis (Part B) Seriesl;
Elseview: Amsterdam, 1989; Vol. 3, pp 417–454; (e) Winkler, M.; Wenk, H. H.;
Sander, W. In Reactive Intermediate Chemistry; Moss, R. A., Platz, M. S., Jones, M.,
Jr., Eds.; Wiley-Interscience: New York, 2004; pp 741–794.
substituted acetylenes with benzynes undergo decomposition to
give complex reaction mixtures. A typical procedure is given in
Ref. 9.
In summary, we have demonstrated a facile synthetic copper-
catalyzed alkyne–aryne method for the one-pot synthesis of sym-
metric and unsymmetrical diary alkynes using microwave heating.
By modulating the generation of arynes from 2-(trimethylsilyl)
phenyl trifluoromethane-sulfonate and its 3-methoxy derivative
with CsF under various conditions, we were able to obtain a signif-
icantly faster strategy for constructing sp–sp2 carbon bonds.
4. Himeshima, Y.; Sonoda, T.; Kobayashi, H. Chem. Lett. 1983, 1211–1214.
5. For an extended list of references, see Ref. 6.
6. Xie, C.; Liu, L.; Zhang, Y.; Xu, P. Org. Lett. 2008, 10, 2393–2396.
7. See, for example: (a) Kamila, S.; Biehl, E. R. J. Heterocycl. Chem. 2007, 44, 407–
412; (b) Kamila, S.; Biehl, E. R. J. Heterocycl. Chem. 2006, 43, 1–6; (c) Kamila, S.;
Koh, B.; Khan, O.; Biehl, E. R. J. Heterocycl. Chem. 2006, 43, 1641–1646; (d)
Kamila, S.; Zhang, H.; Biehl, E. R. Heterocycles 2005, 65, 2493; (e) Kamila, S.;
Zhang, H.; Biehl, E. R. Heterocycles 2005, 65, 2119–2126.
Acknowledgment
We thank the Robert Welch Foundation (Grant N-118) for par-
tial financial support on this work.
8. Roberts, J. D.; Vaughan, C. W.; Carlsmith, L. A.; Semenow, D. A. J. Am. Chem. Soc.
1956, 78, 611–614.
9. Typical procedure: Preparation of 1,2-diphenylethyne: Phenyl acetylene (0.028 g,
0.274 mmol), CuI (5.2 mg, 0.0274 mmol), and CsF (0.099 g, 0.652 mmol) were
charged with an oven-dried tube under the protection of nitrogen. Then, 2-
(trimethylsilyl) phenyl triflate (0.1 g, 0.335 mmol) was added by syringe to a
mixture of CH3CN and toluene (2:2 mL). The reaction mixture was stirred at
150 °C for 30 min under microwave heating. The suspension was filtered and
concentrated under reduced pressure. The residue was purified by preparative
chromatography on TLC-Silica Gel 60 F254 to provide 44 mg (90%) of 1,2-
diphenylethyne.
References and notes
1. Pansegrau, P. D.; Rieker, W. F.; Meyers, A. I. J. Am. Chem. Soc. 1988, 110, 7178–
7184.
2. Roberts, J. D.; Simmons, H. E.; Carlsmith, L. A.; Vaughan, C. W. J. Am. Chem. Soc.
1953, 75, 3290–3291.
3. For selected books, see: (a) Hoffmann, R. W. Dehydrobenzene and Cyloalkynes;
Academic Press: New York, 1967; For selected review articles, see: (b) Gilchrist,