Regioselectively switchable alkyne cyclotrimerization catalyzed by a Ni(ii)/bidentate P-ligand/Zn system with ZnI₂ as an additive

Abstract

A simple catalyst system of Ni(PPh3)2Cl2/dppb or dppm/Zn can effect an efficient and regioselectively controlled alkyne cyclotrimerization to form 1,2,4- (with no additive) or 1,3,5-regioisomers (with the use of ZnI2...

Surface Crystallization Enhancement and Defect Passivation for Efficiency and Stability Enhancement of Inverted Wide-Bandgap Perovskite Solar Cells

“…1,2,4-Tris­(3-thienyl)­benzene (THB) was synthesized using Ni­(PPh 3 ) 2 Cl 2 , 4-(3-thienyl) phenylacetylene, 1, 4-bis (triphenylphosphine) butane, and zinc dust according to the reported method …”

Shape‐ and Size‐Tunable Synthesis of Covalent Organic Cages through Rh‐Catalyzed Regioselective [2+2+2] Cycloaddition

“…Although the 1,3,5-isomer is usually the minor product in the transition-metal-catalyzed [2+2+2] cycloaddition of alkynes, theoretical calculations of rhodium(I)-catalyzed [2+2+2] cycloaddition reactions of arylacetylenes have suggested that electrically biased alkynes may enhance 1,3,5-selectivity. [54,55] There have also been several reports of 1,3,5-selective [2+2+2] cycloadditions of terminal [23,[56][57][58][59][60][61][62][63] or internal alkynes, [56,64] but they suffered from low yield or 1,3,5-selectivity. Even the highyielding and highly 1,3,5-selective In III -catalyzed [2+2+2] cycloaddition of terminal alkynes [57] has not been applied to the cage synthesis due to a stepwise carbometallation mechanism and harsh reaction conditions (PhCl, reflux) but only to the polymer synthesis.…”

Ni0-Catalyzed Regioselective [2 + 2 + 2] Cyclotrimerization of 1,3-Diynes: An Expeditious Synthesis of Hexasubstituted Alkynyl Benzenes

“…Since then, several metal catalysts have been employed successfully for synthesizing such substituted aromatic and heteroaromatic derivatives via [2 + 2 + 2] cyclotrimerizations (Scheme ). The Roşca, Konno, Takeuchi, Ikeda, Hapke, and Yang groups independently reported [2 + 2 + 2] cyclotrimerizations of alkynes catalyzed by transition metal complexes of Fe, Rh, Ir, Co, and Ni, respectively, with tunable regio/chemoselectivity (Scheme b). The methodology has been extended to various unsaturated substrates like enynes, conjugated or isolated diynes, nitriles, and unsaturated carbonyls to provide the corresponding cyclotrimerization products.…”