Investigation of an Efficient Palladium-Catalyzed C(sp)−C(sp) Cross-Coupling Reaction Using Phosphine−Olefin Ligand: Application and Mechanistic Aspects

Abstract

A pi-acceptor phosphine-electron-deficient olefin ligand was found effective in promoting Pd-catalyzed C(sp)-C(sp) cross-coupling reactions. The new protocol realized the cross-coupling of a broad scope of terminal alkynes and haloalkynes in good to excellent yields with high selectivities. Electron-rich alkynes, which are normally difficult substrates in Glaser couplings, could be employed as either nucleophiles or electrophiles. Alkynes bearing similar substituents, such as n-C5H11CCBr and n-C4H9CCH, which usually suffer from homocoupling side reactions under Cadiot-Chodkiewicz conditions, were successfully cross-coupled in the system. Preliminary kinetic studies revealed that the reaction rate was zero-order in the concentrations of both haloalkynes and terminal alkynes and first order in the loading of Pd(dba)2 and exhibited no obvious dependence on the loading of the copper salt. Control experiments with other phosphines such as PPh3 and DPPF as the ligand were carried out. All the kinetic evidence indicated that the phosphine-olefin ligand facilitated the reductive elimination in the catalytic cycle.

Tailored thioxanthone‐based photoinitiators for two‐photon‐controllable polymerization and nanolithographic printing

“… Dibromothioxanthen‐9‐one (DBTX) can be synthesized through a bromination reaction . BDAPT and DAPT can be successfully formed by traditional Sonogashira coupling reactions using a single step . The major product of these reactions (i.e., either the di‐substituted BDAPT or mono‐substituted DAPT) can be controlled by changing the ratio of two different starting materials.…”

Copper(I) Acetate: A Structurally Simple but Highly Efficient Dinuclear Catalyst for Copper‐Catalyzed Azide‐Alkyne Cycloaddition

“…However, the polar organic solvents significantly decreased the catalytic activity of Cat-1 (entries [13][14][15][16]. It is well known that Cu(I) can be easily oxidized to Cu(II) by air; even so, the reactions of entries 7, 9-11 were performed conveniently open to the air.…”

“…To our surprise, its structure was assigned as PhC CCu (4) by elemental analyses and by comparing its IR spectra with that of a commercial sample or samples obtained by reference methods. [15,16] Since 4 when treated with 2a gave the desired product 3a in 98% yield, it was proved to be an intermediate in the CuAAC.…”

Coinage Metal Complexes of Bis‐Alkynyl‐Functionalized N‐Heterocyclic Carbenes: Reactivity, Photophysical Properties, and Quantum Chemical Investigations

“…[78] The progress of the reactionw as easily observed, as [CuCCPh] n ,w hich is otherwise insoluble in commono rganic solvents (except donor-type solvents like, for example, pyridine), slowly dissolved over time. Initially, compound 4 or 5 was treated with [CuCCPh] n in dichloromethane at room temperature.…”