Six C-O based electrophiles, mesylates, sulfamates, esters, carbonates, carbamates and methyl ethers in 1- or 2- position of naphthalene were compared under five different nickel catalyzed cross-coupling conditions with aryl neopentyglyclolboronates containing electron-donating and electron withdrawing substituents. The five catalytic systems were NiCl2(PCy3)2/K3PO4/toluene/110 oC, NiCl2(PCy3)2/CsF/toluene/110 oC, Ni(COD)2/PCy3/K3PO4/toluene/120 oC, Ni(COD)2/PCy3/CsF/toluene/120 oC and Ni(COD)2/PCy3/K3PO4/THF/23 oC. Ni(II) based catalytic systems allowed the cross-coupling of all C-O electrophiles except carbonates when K3PO4 was used as base, while using CsF as base significantly decreased the catalytic activity of Ni(II)-based catalysts. Ni(0)-based catalytic systems were more selective and reactive than Ni(II)-based catalysts when K3PO4 or CsF was used. The reactivity difference in cross-coupling of C-O electrophiles under different catalytic conditions provides possible application in orthogonal cross-coupling methodologies required in the synthesis of biaryl and polyaryl compounds.

Comparison of aryl C-O based electrophiles in nickel catalyzed cross-coupling reactions with aryl neopentylglycolboronates

244th National Meeting (2012)

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