Biaryl formation: palladium catalyzed cross-coupling reactions between hypervalent silicon reagents and aryl halides

Quaternary onium triorgano(difluoro)silicates R(2)(1)R(2)SiF(2)(-)Q(+) were prepared by reaction of the corresponding quaternary onium hydrogendifluoride (Q(+)H(2)F(2)(-)) with a (triorgano)silane or a silyl enol ether. These silicates were isolated in very high yield and purity >99% by excluding halogenated solvents from the synthetic protocol. Ph3SiF2-Bu4N+ (TBAT) was used as phenylating agent of aromatic halides in DMSO, at 120 degreesC and in the presence of 2.5% M equivalents of allyl palladium chloride dimer (APC) as a catalyst. (C) 2003 Elsevier Science B.V. All rights reserved.