- Pd-catalyzed cross-coupling study of bi-functional 3-bromo-4-trifloxycoumarins with triarylbismuth reagents
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Abstract The cross-coupling reactions of functionalized 3-bromo-4-trifloxycoumarins have been explored with threefold arylating triarylbismuth reagents. These palladium-catalyzed reactions afforded chemo-selective C-4 arylations with the facile formation of 3-bromo-4-arylcoumarins in good to high yields. Additionally, palladium-catalyzed arylations of functionalized 3-bromo-4-arylcoumarins also participated in the second arylation to give functionalized 3,4-diarylcoumarins in high yields.
- Rao, Maddali L.N.,Kumar, Abhijeet
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p. 5137 - 5147
(2015/06/30)
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- The palladium(II) / carbon monoxide-mediated biaryl formation from aryltellurium trihalides
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Treatment of aryltellurium trihalides (ArTeX3: Ar=Ph, 4-BrC6H4, 4-MeC6H4, 4-MeOC6H4, 4-BuOC6H4, 4-PhOC6H4, 2-naphthyl; X=Cl,Br) with a palladium(II) salt in acetonitrile at 25 deg C affords, in good yields (29-78 percent), the corresponding biaryls (ArAr) either in the atmosphere or under 1 atm CO.The presence of CO accelerates this aromatic coupling significantly to produce some active palladium carbonyl species, the formation of which was confirmed by IR spectroscopy of Li2PdCl4 in acetonitrile solution under CO; a strong sharp absorption and a weaker sharp one appeared at 2140 and 1908 cm-1, respectively, attributable to the ν(CO) of the (Pd-CO) species.Treatment with alkali after reaction was essential to producing the biaryls.
- Takahashi, Hidetaka,Ohe, Kouichi,Uemura, Sakae,Sugita, Nobuyuki
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p. 227 - 234
(2007/10/02)
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