Single electron transfer-induced coupling of alkynylzinc reagents with aryl and alkenyl iodides

Abstract

Alkynylzinc reagents were found to undergo coupling with aryl and alkenyl iodides to give arylalkynes and alkenylalkynes without the aid of transition metals. The coupling reaction proceeds through a single electron transfer mechanism, where a substoichiometric amount of a phosphine works as an indispensable activator.

Nickel-Catalyzed Decarboxylative Coupling of Alkynyl Carboxylates with Aryl Tosylates and Mesylates

“…CDCl 3 ): δ = 8.77 (s, 1 H), 8.55 (d, J = 4.0 Hz, 1 H), 7.81 (d, J = 7.8 Hz, 1 H), 7.56-7.54 (m, 2 H), 7.38-7.36 (m, 3 H), 7.30-7.26 (m, 1H); the spectroscopic data are consistent with the literature 19. …”

A Novel One‐Step Synthesis of Silicon‐Containing Arylacetylene Resin Catalyzed by Et2Zn with Excellent Processability and Thermal Properties

“…The peak at 3.06 ppm corresponds to the chemical shift of ethynyl protons (peak b), whereas 1.26 ppm and 0.86 ppm (peak *) respectively correspond to the CÀ H chemical shifts of À CH 3 and À CH 2 À , which is the impurity introduced by Et 2 Zn and this is consistent with the impurities in diethylzinc described in the literature. [31] The 1 H NMR spectra of PSA resins synthesized by three different methods are shown in Figure 2. When compared with PSAÀ Zn (seen in Scheme S2 in the Supporting Information), it is evident that the 1 H NMR spectrum of PSA-Et 2 Zn does not have the characteristic peaks at 5.26 ppm, 5.74 ppm, and 6.66 ppm.…”

“…[27][28][29][30] Okura et al developed a coupling reaction for alkynylzinc reagents with aryl and alkenyl iodides and without the aid of transition metal catalysis by mixing and heating all the materials including terminal alkynes and Et 2 Zn (in a 2 : 1 ratio). [31] Huang et al reported the first example of Et 2 Zn mediated silylation of 1-aklynes and chlorosilanes and mechanistic studies that support Zn alkynilides as intermediates in the reaction. [32] This reaction protocol comprises a practical method for the preparation of alkynylsilanes.…”

Electron‐Catalyzed Cross‐Coupling of Arylboron Compounds with Aryl Iodides

“…Among these, Suzuki–Miyaura coupling, which employs arylboron compounds as arylmetals, is one of the most widely used due to the high stability and high availability of the reagents and the high functional‐group tolerance of the reaction . On the other hand, since our group reported the first electron‐catalyzed cross‐coupling, where aryl Grignard reagents are employed and an electron derived from them instead of a transition metal acts as a catalyst, we and other groups have reported transition‐metal‐free cross‐coupling of arylmetals (Zn/Al/Sn) as well as alkyl‐ and alkynylzinc reagents . Herein, we report for the first time that arylboron compounds can be utilized as aryl nucleophiles in the electron‐catalyzed cross‐coupling with the aid of a zinc reagent such as diethylzinc or zinc chloride/potassium tert ‐butoxide…”