Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes
作者:Michael Neumeier、Uttam Chakraborty、Dieter Schaarschmidt、Victor Pena O'Shea、Raul Perez‐Ruiz、Axel Jacobi von Wangelin
DOI:10.1002/anie.202000907
日期:2020.8.3
combinations of visible‐light photocatalysis with metal catalysis have recently enabled the development of hitherto unknown chemical reactions. Dual mechanisms from merging metal‐free photocatalysts and earth‐abundant metal catalysts are still in their infancy. We report a photo‐organo‐iron‐catalyzed cyclotrimerization of alkynes by photoredox activation of a ligand‐free Fe catalyst. The reaction operates
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
Chemo- and Regioselective Intermolecular Cyclotrimerization of Terminal Alkynes Catalyzed by Cationic Rhodium(I)/Modified BINAP Complexes: Application to One-Step Synthesis of Paracyclophanes
the cationicrhodium(I)/DTBM-Segphos complex. This method can be applied to a variety of terminal alkynes to provide 1,2,4-trisubstituted benzenes in high yield and with high regioselectivity. A chemo- and regioselective intermolecular crossed-cyclotrimerization of dialkyl acetylenedicarboxylates with a variety of terminal alkynes has also been developed based on the use of the cationicrhodium(I)/H8-BINAP
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