Synthesis of substituted 1,3-diynes
A cross-coupling of terminal alkynes with 1-bromoalkynes in the presence of copper(I) iodide and tris(o-tolyl)phosphine enables the synthesis of unsymmetrical buta-1,3-diynes in good yields under simple and mild reaction conditions. The scope and limitations of the cross-coupling reaction were investigated.
S. Wang, L. Yu, P. Li, L. Meng, L. Wang, Synthesis, 2011, 1541-1546.
A new Pd-catalyzed protocol realized the cross-coupling of a broad scope of terminal alkynes and haloalkynes in good to excellent yields with high selectivities and without homocoupling using a phosphine-olefin ligand. Electron-rich alkynes, which are normally difficult substrates in Glaser couplings, could be employed as either nucleophiles or electrophiles.
W. Shi, Y. Luo, X. Luo, L. Chao, H. Zhang, J. Wang, A. Lei, J. Am. Chem. Soc., 2008, 130, 14713-14720.
In the presence of palladium(II) acetate and copper(I) iodide, unsymmetrical buta-1,3-diynes were selectively obtained from the reaction of (E)-1,2-diiodoalkenes with terminal alkynes in moderate to good yields at room temperature. Using the same conditions, the coupling of 2-ethynylphenol with (E)-1,2-diiodoalkenes followed by a cyclization at 100°C gives ethynylbenzofurans.
Y. Liang, L.-M. Tao, Y.-H. Zhang, J.-H. Li, Synthesis, 2008, 3988-3994.
A carbenoid Fritsch-Buttenberg-Wiechell (FBW) rearrangement of a substituted dibromoolefinic precursor is used to generate a lithium acetylide, and subsequent trapping with carbon-based electrophiles provides a wide range of di- and triynes. The lithium acetylide formed from the FBW reaction can also undergo transmetalation to provide zinc, copper, tin, or platinum acetylides.
T. Luu, Y. Morisaki, N. Cunningham, R. R. Tykwinski, J. Org. Chem., 2007, 72, 9622-9629.
A facile and environmentally friendly synthetic method for a variety of symmetrical 1,3-diyne derivatives is based on a Pd/C-CuI-catalyzed homocoupling reaction of terminal alkynes. The reaction was efficiently catalyzed by an extremely low loading of Pd/C and CuI in the presence of molecular oxygen as the oxidant without any phosphine ligands and bases.
T. Kurita, M. Abe, T. Maegawa, Y. Monguchi, H. Sajiki, Synlett, 2007, 2521-2524.
A palladium-catalyzed dimerization of terminal acetylenes with iodosylbenzene as oxidant allowed the preparation of various diynes in good yields in a short period of time at room temperature.
J. Yan, F. Lin, Z. Yang, Synthesis, 2007, 1301-1303.