Iron-catalyzed regioselective cyclotrimerization of alkynes to benzenes
作者:Suhas Shahaji Gawali、Chidambaram Gunanathan
DOI:10.1016/j.jorganchem.2018.12.007
日期:2019.2
catalyzed the regioselective [2+2+2] cyclotrimerization of terminal aryl and alkyl alkynes to provide the 1,2,4-trisubstituted benzene molecules. Interestingly, internal alkynes also exhibited similar cyclization and resulted in hexa-substituted benzene compounds. Increased steric bulk on pincer ligands diminished the selectivity for cycloaddition. Cyclotrimerization reactions proceeded at room temperature
Exploiting Guanidine as a Ligand in Cobalt-Catalyzed Alkyne Cyclotrimerizations
作者:James Stambuli、Chad Eichman、Jason Bragdon
DOI:10.1055/s-0030-1259931
日期:2011.5
The synthesis of polysubstituted arenes is accomplished via the regioselective cyclotrimerization of alkynes utilizing a guanidine-ligated cobalt catalyst.
A new [2+2+2] cycloaddition procedure relying on the use of an air-stable iron precatalyst is described, which allows the construction of aromatic and nitrogen-containing heteroaromatic rings in green solvents and mild conditions. Cycloadditions and cross-cycloadditions between 1,6- or 1,7-diynes and alkynes are reported, with a broad functional tolerance, leading to a variety of functionalizable scaffolds
Grubbs' catalyst [(PCy3)(2)Cl2Ru=CHPh, 7] was shown for the first time to be an effective catalyst for the mild intermolecular cyclotrimerization of terminal alkynes (1-6). The reaction is general and the isomeric trisubstituted benzene derivatives (8-13) were isolated in good to excellent yields. (C) 1999 Elsevier Science Ltd. All rights reserved.