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Unsymmetrical diarylalkynes were synthesized in moderate to good yields through a three-component one-pot procedure involving thermocontrolled sequential Sonogashira reactions with potassium ethynyltrifluoroborate and two different reactive aryl halides. The one-pot procedure was initiated by the palladium/copper-catalyzed Sonogashira coupling of potassium ethynyltrifluoroborate to an aryl iodide or electron-deficient aryl bromide at 40 °C. Following a subsequent deboronative Sonogashira reaction of the in situ generated potassium (arylethynyl)trifluoroborate, a second coupling to a less-active electron-rich aryl bromide at 80 °C, without any additional palladium/copper catalyst or base, gave rise to unsymmetrical diarylalkynes.

In this study, a novel and simple method for the preparation of various arylnaphthalene lactone natural products was developed and used to synthesize diphyllin (10), justicidin A (12), cilinaphthalide B (13), taiwanin E (15), chinensinaphthol (16), taiwanin E methyl ether (17), chinensinaphthol methyl ether (18), justicidin C (21) and justicidin D (22). The syntheses proceeded via HauserKraus annulation of cyanophthalides (7a and 7b) and SuzukiMiyaura cross-coupling of arylnaphthalene lactones having a sulfonate group (9, 14, 19, and 20) with the corresponding potassium aryltrifluoroborates.

Potassium arylethynyltrifluoroborates, the intermediates generated by the Sonogashira reaction of potassium ethynyltrifluoroborate with various aryl halides, were directly coupled with azides in the presence of a stoichiometric amount of CuI under aqueous conditions, and the desired 1,4-disubstituted 1,2,3-triazoles were isolated in good yields. Both electron-donating and electron-withdrawing substituents on the potassium arylethynyltrifluoroborates gave moderate to excellent yields of the isolated products.

A novel series of 1,4-disubstituted 1,2,3-triazole-containing potassium trifluoroborates were prepared in good to excellent yields from the corresponding organohalides and potassium ethynyltrifluoroborate through a regioselective one-pot Cu-catalyzed azide–alkyne cycloaddition (CuAAC) reaction. Further Suzuki–Miyaura cross-coupling of these (organo-1,2,3-triazol-4-yl)trifluoroborates with aryl and alkenyl bromides by using a PdCl2(dppf)·CH2Cl2/TBAB [dppf = 1,1′-bis(diphenylphosphanyl)ferrocene, TBAB = tetrabutylammonium bromide] system under microwave irradiation was explored.