Palladium-Catalyzed Cross-Coupling of Electron-Poor Terminal Alkynes with Arylboronic Acids under Ligand-Free and Aerobic Conditions

Abstract

Palladium-catalyzed cross-coupling reaction of terminal alkynes with arylboronic acids has been described. In the presence of Pd(OAc)(2) and Ag(2)O, a variety of terminal alkynes, including electron-poor terminal alkynes, smoothly underwent the reaction with numerous boronic acids to afford the corresponding internal alkynes in moderate to good yields. Moreover, this methodology was applied to the synthesis of 1H-isochromenes and diynes. It is noteworthy that the reaction proceeds under ligand-free and relative lower loading Pd conditions, and the maximal TONs (turnover numbers) of the reaction are up to 720,000.

Au(I)/Au(III)-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

“…All kinds of palladium catalyst systems [4–10] and other metal catalyst systems [3] have been developed for facilitating the Sonogashira cross-coupling, as well as expanding the substrate scope [11–14]. Various examples have recently been reported for the palladium-catalyzed Sonagashira-type cross-coupling of terminal alkynes with arylboronic acids [13], and the Pd(0)/Pd(II) catalytic cycles have been well studied. Nevertheless, this transformation catalyzed by gold, involving Au(I)/Au(III) catalytic cycles has, as yet, been less explored [15–22].…”

Facile synthesis of substituted alkynes by nano-palladium catalyzed oxidative cross-coupling reaction of arylboronic acids with terminal alkynes

“…However, dimerized byproducts of the reactants were always generated. Moreover, the reaction times of either palladium or copper catalyzed coupling reactions were generally very long and the yields were not always very satisfactory [20]. Thus the development of green and effective catalytic system for this cross-coupling reaction is urgent.…”

Copper‐Catalyzed Amidation of Acids Using Formamides as the Amine Source

“…N , N ‐Diethyl‐3‐phenylpropiolamide (3tc): 20 Colorless oil. 1 H NMR (500 MHz, CDCl 3 ): δ = 7.53 (t, J = 6.5 Hz, 2 H), 7.43–7.40 (m, 1 H), 7.36 (t, J = 7.5 Hz, 2 H), 3.69–3.65 (m, 2 H), 3.50–3.46 (m, 2 H), 1.28 (t, J = 7.5 Hz, 3 H), 1.18 (t, J = 7.5 Hz, 3 H) ppm.…”

“…1‐Morpholino‐3‐phenylprop‐2‐yn‐1‐one (3tf): 20 Yellow oil. 1 H NMR (500 MHz, CDCl 3 ): δ = 7.55–7.53 (m, 2 H), 7.44–7.41 (m, 1 H), 7.38–7.35 (m, 2 H), 3.84 (t, J = 5.0 Hz, 2 H), 3.75 (t, J = 5.0 Hz, 2 H), 3.70 (s, 3 H) ppm.…”

“…N ‐Benzyl‐ N ‐methyl‐3‐phenylpropiolamide (3tg): 20 Yellow solid. 1 H NMR (500 MHz, CDCl 3 ): δ = 7.55 (d, J = 7.0 Hz, 1 H), 7.50 (d, J = 5.0 Hz, 1 H), 7.41–7.28 (m, 8 H), 4.86, 4.67 (s, 2 H), 3.19, 2.93 (s, 3 H) ppm.…”